## DRAFT RISK ASSESSMENT REPORT

VINYL ACETATE

CAS No: 108-05-4
EINECS No: 203-545-4

GENERAL NOTE

Please note that this draft risk assessme nt report contains the following documents:

- R059_0505_enV: ENV part, May 2005 (pages 2-83, version se nt in October 2005 to SCHER for their opinion)

- R059_0805_hh: HH part, July 2008 ( pages 84-286, version sent in July 2008 to SCHER for their opinion)
- the appendices

# RISK ASSESSMENT

Vinyl acetate

CAS-No.: 108-05-4

EINECS-No.: 203-545-4

Draft of 04.05.2005R059_0505_env Draft of 04.05.2005 Information on the rapporteur
Contact point:
Bundesanstalt für Arbeitsschutz und Arbeitsmedizin (BAuA) Anmeldestelle Chemikalien / Zulassungsstelle Biozide (Federal Institute for Occupational Safety and Health Division for Chemicals and Biocides Regulation) Friedrich-Henkel-Weg 1-25
44149 Dortmund (Germany)

fax: +49(231)9071-2679 e-mail: chemg@baua.bund.de

This document is the 3rd draft of the Envi ronment Section of the Comprehensive Risk Assessment Report of Vinyl acetate , a substance chosen from the EU 1 st Priority List in 1994, which is distributed for the last visit written procedure.
The Comprehensive Risk Assessment Report of Vinyl acetate was discussed preliminary (written procedure) at the TM II / 2001 (June 2001).
The Human Health part was discussed first in depth at the TM I/2002 (March 2002), second in depth at the TM IV/2002 (December 2002) and last visit at the TM II/2003 (June 2003).
The Environmental part was discussed in de pth at the TM III/2002 (August 2002) and further in depth at the TC NES IV 04 (December 2004).

CAS No.: 108-05-4 2R059_0505_env Draft of 04.05.2005
CONTENTS

0 OVERALL CONCLUSIONS/RESULTS OF THE RISK ASSESSMENT 6

1 GENERAL SUBSTANCE INFORMATION 8

2 GENERAL INFORMATION ON EXPOSURE 12
2.1 Exposure sources 12
2.1.1 Production 13

2.1.1.1 Global production figures 13
2.1.1.2 Production in Western Europe 13 2.1.2 Processing 14
2.2 Uses 17
3 ENVIRONMENT 20
3.1 Environmental exposure 20
3.1.1 General discussion 20

3.1.1.1 Releases into the environment 20
3.1.1.1.1 Production of the monomer 20
3.1.1.1.2 Processing of vinyl acetate monomer 21
3.1.1.1.3 Compounding and use of materials cont aining vinyl acetate (co)polymers 25
3.1.1.1.4 Storage and Transport 25
3.1.1.2 Degradation in the environment 25
3.1.1.2.1 Degradation in the atmosphere 25
3.1.1.2.2 Degradation in the aquatic compartment 26
3.1.1.2.3 Degradation in soil and sediment 27
3.1.1.3 Distribution 28
3.1.1.3.1 Adsorption 28
3.1.1.3.2 Volatility 29
3.1.1.3.3 Modelling of distribution 29
3.1.1.3.4 Elimination in Sewage Treatment Plants (STP) 30
3.1.1.3.5 Accumulation 30 3.1.2 Exposure Assessment for the Aquatic Compartment 30

3.1.2.1 Estimation of local environmental concentrations (C local water ) 31

3.1.2.1.1 Production of the monomer 31
3.1.2.1.2 Processing of the monomer 32
3.1.2.1.3 Man ufacture of synthetic fibres 35
3.1.2.1.4 Man ufacture of coatings and printing inks 35
3.1.2.1.5 Man ufacture of adhesives 37

CAS No.: 108-05-4 3R059_0505_env Draft of 04.05.2005

3.1.2.1.6 Paper recycling and use of printing inks and paintings 37
3.1.2.2 Measured data in aqueous environment 37 3.1.3 Exposure Assessment for the Atmosphere 37

3.1.3.1 Estimation of local concentrations (Clocal air ) 37
3.1.3.1.1 Production of the Monomer 38
3.1.3.1.2 Processing of the Monomer 39
3.1.3.1.3 Man ufacture of synthetic fibres 40
3.1.3.1.4 Man ufacture of coatings and printing inks 40
3.1.3.1.5 Man ufacturing of adhesives 41
3.1.3.2 Measured data in the atmosphere 41 3.1.4 Exposure assessment for the terrestrial compartment 41 3.1.5 Non compartment specific exposure relevant to the food chain 43 3.1.6 Regional concentrations 43
3.2 Effects assessment: Hazard identification and Dose (concentration) - response (effect) assessment 45 3.2.1 Effects assessment for the aquatic compartment (including sediment) 45

3.2.1.1 Test results 45
3.2.1.1.1 Criteria for validation 45
3.2.1.1.2 Fish 48
3.2.1.1.3 Aquatic invertebrates 49
3.2.1.1.4 Aquatic algae 50
3.2.1.1.5 Microorganisms 52
3.2.1.2 Calculation of Predicted No Effect Concentration (PNEC) 52
3.2.1.2.1 Surface water (PNEC aqua ) 52
3.2.1.2.2 Sewage treatment plants (PNEC STP ) 52
3.2.1.2.3 Sediment (PNEC sed ) 53 3.2.2 Effects assessment for the terrestrial compartment 53

3.2.2.1 Terrestrial effect data 53
3.2.2.2 Calculation of PNEC soil 54 3.2.3 Effects assessment for the atmosphere 54

3.2.3.1 Biotic effects 54
3.2.3.2 Abiotic effects 55
3.2.3.2.1 Global warming 55
3.2.3.2.2 Troposheric ozone 55
3.2.3.2.3 Stratospheric ozone (ODP) 55
3.2.3.2.4 Acidification 55 3.2.4 Non compartment specific effects relevant to the food chain 55

CAS No.: 108-05-4 4R059_0505_env Draft of 04.05.2005
3.3 Risk characterisation 56 3.3.1 Aquatic compartment (incl. sediment) 56 3.3.2 Atmosphere 60 3.3.3 Terrestrial compartment 61 3.3.4 Non compartment specific effects relevant to the food chain 62 3.3.5 Marine Assessment including PBT Assessment 62

3.3.5.1 PBT Assessment 62
3.3.5.2 Marine Assessment 63
4 HU MAN HEALTH 65
4.1 HU MAN HEALTH (TOXICITY) 65 4.1.1 Exposure assessment 65

4.1.1.1 Indirect exposure via the environment 65
5 CONCLUSIONS / RESULTS 66
6 REFERENCES 68

CAS No.: 108-05-4 5R059_0505_env Draft of 04.05.2005

0 OVERALL CONCLUSIONS/RESULTS OF THE RISK ASSESSMENT

CAS No. 108-05-4

EINECS No. 203-545-4
IUPAC Name Vinyl acetate

Overall results of the risk assessment:
(x) i) There is need for further information and/or testing
(x) ii) There is at present no need for furt her information and/or testing and for risk reduction measures beyond those which are being applied already
() iii) There is a need for limiting the risks; risk reduction measures which are already being applied shall be taken into account

Summary of conclusions:

Environment
As a follow up to conclusion (i), which was drawn in the first draft of the Environment Section of the Comprehensive Risk Assessment Report of Vinyl acetate (August 2002), further acute and long-term toxicity tests were performed for the aquatic compartment and more data on a number of production and processing sites were obt ained, leading to the following revised risk characterisation.

conclusion i):

Terrestrial compartment
A risk to the local terrestrial compartment wa s identified for the life cycle stages of vinyl acetate production and processing. This conclusion applies to one major production site (site number 26) due to aerial deposition of vinyl acetat e in the vicinity of the site and for the generic processing scenario calculated for the local main source.
There is a need for further information and/or testing to adequately characterize the potential risks to the terrestrial compartment by refining the PNEC soil . It is recommended to perform an earthworm acute toxicity test (OECD 207) and a terrestrial plants growth test (OECD 208). The need for further testing should be reconsid ered in case that risk reduction measures are being applied at the site indicating a risk to the terrestrial compartment (site number 26). If no risk remains after risk reduction measures have been applied for the life cycle stage of vinyl acetate production, conclusion ii) should follow.

CAS No.: 108-05-4 6R059_0505_env Draft of 04.05.2005

conclusion ii):

Aquatic compartment
A risk to the local or regional aquatic comp artment (surface water and sediments) was not identified for production and processing of vinyl acetate. This conclusion applies to all sites.

Atmospheric compartment
Based on a qualitative risk characterisation, no unacceptable risk for the atmosphere is expected from vinyl acetate. The substance is rapidly removed from air by chemical breakdown, adsorption to airborne particles or aerosols, and wet deposition. Furthermore, air concentrations indicate a negligible risk with regard to ecotoxicity.

Non-compartment specific effects
Non compartment specific effects (secondary pois oning) of vinyl acetate are not expected as there is no indication that the substance has potentially bioaccumulative properties.

Marine Assessment including PBT assessment

VAM does not meet the PBT/vPvB criteria. A risk for the regional or local marine environment is not expected.

Hu man Health

Workers

Consumers
Man exposed indirectly via the environment

CAS No.: 108-05-4 7R059_0505_env Draft of 04.05.2005

1 GENERAL SUBSTANCE INFORMATION

Identification of the substance

CAS No.: 108-05-4

EINECS No.: 203-545-4

IUPAC Name: Vinyl acetate

Synonyma: Acetic acid vinyl ester

Empirical formula: C 4 H 6 O 2

Structural formula:



## CH 2 

## CH
O CH 3 

## O

Molecular weight: 86 g/mol

Purity/impurities, additives

Purity: 99.8 % w/w

Impurities: ≥ 0.03 - 0.1 % w/w water

≥ 0.005 - 0.01 % w/w acetic acid

≥ 0.005 - 0.02 % w/w acetaldehyde
Additives: hydrochinone or hydrochinone mono methyl ether as stabilisator

0.00015 - 0.002 % w/w

CAS No.: 108-05-4 8R059_0505_env Draft of 04.05.2005

Table 1-1: Physico-chemical properties

Physical state liquid at 20 °C Melting point - 93.2 °C Handbook of Chemistry and Physics, 1980 - 1981 Boiling point + 72.7 °C Merck Index, 1996 Relative density 0.932 at 20 °C Merck Index, 1996 Vapour pressure 120 hPa at 20 °C Hoechst AG, 1994c
Surface tension 24 mN/m at 20 °C (pure substance) Handbook of Chemistry and Physics, 1980 - 1981 Water solubility 20 g/l at 20 °C Merck Index, 1996
Partition coefficient logPow 0.7 Hoechst AG, 1992 Flash point - 8 °C (DIN 51755) CHEMSAFE, 1994 Auto-flammability, ignition temperature 385 °C (DIN 51794) CHEMSAFE, 1994

Explosive properties not explosive due to structural reasons Oxidizing properties not oxidizing due to structural properties

Vapour pressure: Vapour pressure values were available from safety data sheets, product information and literature without any details about the used methods. All values correlate well with the boiling point of 72.7 °C (Clausius-Clapeyron).

Water solubility: The water solubility is 20 g/l at 20 °C acco rding to safety data sheets and product information. No further information about the determination method is available.

Partition coefficient: According to literature data the partition coe fficient was determined experimentally (HPLC method: logPow 0.21, shaking method: l ogPow 0.73). The calculation with CLOGP3- Software resulted in a logPow of 0.7. Due to the agreement of experimentally and calculated values a logPow of 0.7 was used for the risk assessment.

CAS No.: 108-05-4 9R059_0505_env Draft of 04.05.2005

Classification

• (Classification according to Annex I)
F R 11 Highly flammable

• (Proposal of the rapporteur)

The current classification included in Annex I to Directive 67/548/EEC is only due to human health effects and does not yet consider envir onmental effects of vinyl acetate. Based on the data presented in the environmental section of this risk assessment report and the criteria of Directive 93/21/EEC, the rapporteur proposes the s ubstance not to be classified and labelled for environmental risks.

The classification included in Annex I to Di rective 67/548/EEC does not yet include toxic effects. According to the data presented belo w and the criteria of Directive 93/21/EEC, vinyl acetate should be classified as follows and assigned the risk phrases:

Harmful R 20 Harmful by inhalation

Irritant R 36/37/38 Irritating to eyes, respiratory system, and to skin

Sensitizing R 43 May cause sensitization by skin contact

Carcinogenic, cat. 2 R 45 May cause cancer
Human data on irritation/corrosion caused by vinyl acetate are not available. Vinyl acetate has proven to cause irritation or corrosion to the sk in of rabbits depending on the duration of the skin contact. According to EU regulations (basing on effects seen after a single 4-hours occlusive dermal exposure) the substance has to be classified as irritant. The eye irritation potential of the compound seems to be similar as judged on the basis of poorly documented eye irritation tests with rabbits. Acute inhalation tests with rats demonstrated severe irritation in the respiratory tract of the animals. T hus, vinyl acetate should be labelled “R 36/37/38, Irritating to eyes, to respiratory system and to skin“.
It has to be noted that a positive Buehler Test with commercial grade vinyl acetate is available. Based on this evidence vinyl acetat e (commercial grade) should be labelled as “R 43 - May cause sensitization by skin contact”.
There is clear evidence for the carcinogenicity of vinyl acetate in two animal species and in both sexes. The carcinogenic potential was demonstr ated for the inhalation and oral route of administration. Vinyl acetate was carcinogenic at the surface epithelium of multiple sites along the exposure routes. No species-specific mode of action for vinyl acetate carcinogenesis was identified. A reasonable threshold mechanism could not be identified for all tumors and tumor sites which finding does not allow to clar ify whether vinyl acetate is rather genotoxic and cancerogenic and not a genotoxic cancerogen. The data from human experience are inadequate for the evaluation of the carcinogenicity of vinyl acetate in humans.

CAS No.: 108-05-4 10R059_0505_env Draft of 04.05.2005 In Germany, vinyl acetate is assigned to the MAK-pregnancy category "D" denoting that the current data base is not sufficient for final ev aluation of developmental toxicity. However it is outlined that vinyl acetate was evaluated for repr oductive toxicity in one species (rat) already with negative results. If this latter outcome c ould be verified in additional species vinyl acetate could be assigned to category "C" deno ting that no risk for adverse developmental effects have to be expected for female work ers in compliance with the respective MAK value of 10 ppm.

CAS No.: 108-05-4 11R059_0505_env Draft of 04.05.2005

2 GENERAL INFORMATION ON EXPOSURE

2.1 EXPOSURE SOURCES
Exposure of man and environment to vinyl acet ate monomer (VAM) may result from releases during each of the consecutive steps downstream the supply chain. These are production of the substance, polymerisation of the monomer, compounding operations involving the polymers, and eventually use of the end products.

Production synthesis of the m onom er ▼
Use processing = (co)polym erisation of the m onom er (co)polym ers are m a rketed as dispersions, solid resins or solutions ▼ Compounding handling of the (co)polym ers, e.g. m a nufacture of ready-to-use products like paints, adhesives, textile f i nishing agents, etc. ▼

---------------------------------------------------------------------------- End user

m a nual end-user: e.g. painter m a n, floor layer, carpenter, etc. industrial end-user: e.g. printer, m a nufacturer of finished film ▼
Consumer e.g. painted walls, glued flooring, glued furniture, printed card, packed food, etc.

The first three stages in the chain, i.e. m a nufacture of the m onom er, polym erisation of (co)polym ers, and com pounding of (co)polym ers are in m o st cases conducted by different

com p anies and at separate locations. Notwithst anding, there is a sm all num ber of sites where both production of the m onom er and further polym er izing is carried out, while there are other cases where VAM is (co)polym erized and subsequently also com pounded.
Only a few m a nufacturers of VAM exist in the EU, whereas the num ber of com p anies polym erising the m onom er and in particular the num ber of downstream users of the polym ers
CAS No.: 108-05-4 12R059_0505_env Draft of 04.05.2005 is considerably higher. For example, ther e are no more than two VAM manufacturers in Germany that use parts of the produced VAM volume to manufacture vinyl acetate (co)polymers. Similarly, just six out of fifty- three European manufacturers of coating/printing inks manufacture the required polymer constituents from the monomer on-site.
Production sites of VAM and facilities produci ng the (co)polymers, but also compounding operations are typical point sources of VAM emissions. Any VAM entering the environment from the latter type of operation results from releases of monomer residuals remaining with the processed (co)polymers.
Finally, diffusive releases of residuals may occu r during end-use of the finished products that contain vinyl acetate (co)polymer constituents.

2.1.1 Production
Vinyl acetate is produced by a catalytic vapour- phase reaction of ethylene and acetic acid in gas phase, liquid phase or a fluidised-bed process.

2.1.1.1 Global production figures
The worldwide demand for VAM reportedly am ounted to 4.3 million t/a in 2003, representing an overall operating rate of about 86 % of a maximum global production capacity of 5 million t/a. The main production capacities are located in Asia (43 %) and North America (34 %), followed by Western Europe on third rank (18 %) (Chemical Week, 2003).

2.1.1.2 Production in Western Europe
A questionnaire was launched by the European Chemical Industry Council (CEFIC) among member companies in 2000 and updated in 2002 to collect data on produced and processed volumes of vinyl acetate monomer in Europe. Fi ve producers of VAM were identified with a nominal production capacity of 800,000 t/a (cf. Table 2-1 ). Fluctuating operating rates (additional capacities brought online, partly o ffset by shutting down other plants) make it difficult to provide a general figure for the annual production volume of VAM in the EU.
For comparison, the production volume of VAM reported by the CEFIC Acetyls Sector Group (ASG) for Western Europe was a bout 715,000 tonnes in 2002. Additionally, total purchases 1 in 2002 accounted for almost 250,000 tonnes. Along with an opening stock 2 of approximately 80,000 tonnes, the “total supply” for 2002 amounted to 1,045,000 tonnes.
From the total supply of about 1,045,000 tonnes, some unquantified amounts were exported outside Western Europe again (figures were not given by industry for confidentiality reasons).

1 Purchase from outside Western Europe but also from co-producers in Western Europe
2 Includes all product produced or purchased but not yet invoiced or transferred to internal captive use, e.g. product in storage or in transit (should be equal to the closing stock of the previous period).
CAS No.: 108-05-4 13R059_0505_env Draft of 04.05.2005
With an end stock 3 of less than 50,000 tonnes in 2002, approximately 750,000 tonnes of VAM were marketed in Western Europe that year (all figures provided by CEFIC ASG).
The outcome of the CEFIC survey was in poor consistency with data retrieved from the IUCLID database (as of May 1999). A number of the companies included in the CEFIC survey were not covered by the IUCLID data - and vice versa. Several of the enterprises had discontinued to exist as a business entity, owing to an intensive restructuring process of the market (mergers, acquisitions and divestitures of business segments). In some cases it turned out that some IUCLID-mentioned capacities ha d been only sales bureaus, whereas other facilities had meanwhile been shut down. IUCLID data were therefore left aside.

2.1.2 Processing
Unlike for production, no exact figure of the pr ocessed volume of vinyl acetate can be extracted from the statistics provided by the CEFIC Acetyls Sector Group (ASG). The provided data is difficult to balance for impor t/export and purchases/sales as ASG statistics comprise all Western European countries, whic h does not coincide with EU countries, and some parts of the statistics are confidential, thus were not disclosed to the rapporteur.
According to the CEFIC Acetyls Sector Group, the total supply of VAM in Western Europe was approximately 1,045,000 tonnes in 2002, ba sed on a production volume of about 715,000 t, total purchases of about 250,000 t and an opening stock of about 80,000 t. When exports, sales, captive use and closing stoc k are deducted, approximately 750,000 t entered the open market in Western Europe in 2002. From this tonnage, an unknown amount is sold to non-EU countries in Western Europe (Switzerland, Turkey, Iceland, Norway), with the remaining tonnage of VAM bei ng sold and processed in the EU. Some amounts of the total VAM supply of 1,045,000 tonnes is directed to captive use 4 and also processed in the EU, but figures on captive use are not provided. As sales to non-EU countries in Western Europe and captive use were not quantified, the exact processing volume in the EU cannot be determined. It is therefore assumed to be in the range of 750,000 – 800,000 tonnes per year.
Responses to the CEFIC questionnaire came eith er from individual processors or industry associations of processing companies. One industry association (CEPE) did not provide information broken down to individual members or processing sites, but for reasons of confidentiality submitted aggregated, in part statistically evaluated data (max./min. values or average means) which were compiled from a questionnaire among member companies. In addition to the CEFIC data, other processing s ites could be identified and consulted. Based on this data collection, the actual total processing volume of VAM may amount to 474,900 tonnes per year in the EU (cf. Table 2-1 ).

3 Closing or end stock of the previous period. Includes all product produced or purchased but not yet invoiced or transferred to internal captive use, e.g. product in storage points or products in transit.
4 All product transferred internally in Western Europe whether from own production or purchased.
CAS No.: 108-05-4 14R059_0505_env Draft of 04.05.2005

Figure 2-1 Market statistics of VAM for 2002, based on CEFIC Acetyls Sector Group.

It has to be concluded that the data provi ded on production and processed volumes of VAM do not match very well:

Based on single sites: Based on market statistics :
Production 800,000 tonnes 715,000 tonnes Processing 474,900 tonnes 750,000 - 800,000 tonnes (estimate)

This imbalance may be due to a number of reasons:

 Figures on volumes were reported for di fferent business years and reflect the dynamics of a market which is characterized by continuous restructuring activities

 Some annual production data are based on nominal capacities, thus do not reflect actual figures which may change from year to year

 Production figures are rounded to nearest 10,000 t/a

 Downstream users did not reply to the questionnaire

 Data are not corrected for import/export or sales/purchases

CAS No.: 108-05-4 15R059_0505_env Draft of 04.05.2005 The maximal difference between reported produc tion volume and specific processing data for individual sites is 325,000 t/a (= 800,000 t/a - 475,000 t/a). It is therefore assumed that a number of processing sites exist that were not covered by the CEFI C questionnaire. As no information on these sites is available, a ge neric risk characterization will be conducted. A fraction of main source of 0.15 and 300 emission da ys are assumed (Tab. B3.2 of the TDG) to estimate the fraction of the total emissions that is expected to be released through the main local point source (worst case scenario for the local environment). The estimated total emissions that are released during processi ng of the total volume of 325,000 t/a are included in the calculation of the regional and continental background concentrations.
Specific local risks were calculated for the production and processing sites that could be identified (cf. Table 2-1 ). In several cases it could not be clarified whether the term “use” in the questionnaire was interpreted by the responde rs as (co)polymerisation, or compounding of already polymerised material, or both. If not sp ecified otherwise it was assumed that the data referred to (co)polymerisation, although this may overestimate emissions in some cases. For confidentiality reasons, sites were coded. Fi ve producers of VAM were identified being located in four EU member states (France, Germany, Spain and UK). Identified processing plants are located in Belgium, Denmark, Fi nland, France, Italy, Germany, the Netherlands, Spain and UK. No information on geographi cal locations was disclosed by industry associations that provided only aggregated data.

Table 2-1: Production and/or processed volumes of VAM identified within the EU

Site code Produced volumes Processed volumes Data source
1 30,000 CEFIC
2 10,000 CEFIC
3a 6,000 CEFIC/CIRFS
3b 10,000 CEFIC/CIRFS
3c 8,000 CEFIC/CIRFS
3d 4,000 CEFIC/CIRFS
4/5 110,000 90,000 CEFIC
6 25,000 CEFIC
7* 10,810 CEPE
8 15,000 CEFIC
9 9,100 CEFIC
10 15,000 CEFIC
11 110,000 CEFIC
12 36,000 CEFIC
13 280 CEFIC
14 2,000 CEFIC/FEICA
15 2,200 CEFIC/FEICA

CAS No.: 108-05-4 16R059_0505_env Draft of 04.05.2005

Site code Produced volumes Processed volumes Data source
16 400 CEFIC/FEICA
17 300 CEFIC/FEICA
18 14,000 CEFIC/FEICA
19 25,000 CEFIC/FEICA
20** 0 0 CEFIC/FEICA
21 200,000 CEFIC
22 100,000 CEFIC
23 17,000 CEFIC
24 5,000 pers. communicated
25 6,910 pers. communicated
26 140,000 pers. communicated
27 250,000 pers. communicated
28 8,000 pers. communicated
29 6,500 pers. communicated
30 8,400 pers. communicated ∑ 800,000 474,900
CEFIC: European Chemical Industry Council CEPE: Conseil Européen des Industries des Peintures, Encres d’Imprimerie et Couleurs d’Art CIRFS: Comité International de la Rayonne et des Fibres Synthetiques FEICA: Fédération Européenne des Industries de Colles et Adhésifs * As communicated by industry association CEPE, most manufacturers buy polymer emulsions (PVA) ready for use and do not polymerise VAM themselves: 52 companies reported in a questionnaire to use PVA at 116 different sites for making printing inks, paintings and coatings. The total volume of VAM polymers was 43,524 t in 2000. The processing volume in the table re fers to the two companies still polymerising VAM. ** confirmation of conducting merely compounding ope rations, i.e. handling of the (co)polymers.

2.2 USES
Vinyl acetate monomer is solely used as an intermediate in chemical industry for manufacturing (polymerisation) of vinyl acetat e (co)polymers (IC 3 / UC 33). Hence it is concluded that the entire production volume of VAM is used up for the manufacture of various (co)polymers, mainly polyvinyl acetate.
Apart from manufacture of homopolymers the m onomer is combined with other monomers like ethylene, vinyl chloride and acrylic acid es ters to form various types of co-polymers. According to the Directory of Chemical Pr oducers Western Europe (SRI International, 1997/98) two types of co-polymers involving ethylene are produced:

CAS No.: 108-05-4 17R059_0505_env Draft of 04.05.2005 (i) ethylene-vinyl acetate co-polymer resins (EVA) with a production capacity of approximately 1 million t/a, and
(ii) vinyl acetate-ethylene co-polymer resins (VAE) with a production capacity of approximately 300,000 t/a.
Polymers manufactured from VAM are used in a broad spectrum of products, including water-based paints, printing inks, lacquer, cer amic, adhesives for packaging and construction, paper finishing, and protective colloids for va rious materials. Other important products include textile fibres, paper coating and inks (Table 2-2). The content of residual VAM in homo- and co-polymers depends on the product, sp anning a wide range of reported values of less than 5 ppm up to 6,000 ppm (Celanese, 2000) . According to the CEFIC compilation of data from industry, the majority of polymer s have an average content of around 1,000 - 2,000 ppm or less. Ullmann (1998) provides a quan titatively weighted median value for the monomer content of roughly 3,000 ppm. The latter value will be used for estimating diffuse releases of VAM from (co)polymers and end-use products in this document.
In addition, vinyl acetate (co)polymers are used as feedstock for manufacture of vinyl alcohol (co)polymers (e.g. polyvinyl alcohol). Polyvinyl alcohol is obtained by hydrolysing polyvinyl acetate. The production capacity w ithin the EU is reported at > 100,000 t/a (SRI International, 1997/98). Commercial grades of polyvinyl alcohol differ in the degree of polymerisation (molecular mass) and degree of hydrolysis (re sidual polyvinyl acetate content). Along with saponification (alkaline hydrolysis of fatty aci d esters) of the acetyl moieties of polyvinyl acetate, monomer residuals are getting eliminat ed as well. A minor fraction of polyvinyl alcohol ends up in the manufacture of polyvinyl acetales, e.g. of polyvinyl butyral (PVB).
A broad quantitative breakdown of the use pattern of vinyl acetate is available for Germany for 1990. In this year, approximately 68 % of th e produced vinyl acetate was used mainly for the manufacturing of polyvinyl acetate and, to a less extent, for the manufacturing of copolymers. 32 % of the produced vinyl acet ate was manufactured to polyvinyl alcohol (BUA, 1993). Vinyl acetate occurs as residual monomer in homo- and copolymers based on vinyl acetate and in products or formulations based on these polymers. As polyvinyl alcohol is produced by trans esterfication (saponifica tion) of vinyl acetate (co)polymers, residual vinyl acetate monomer does not occur in polyvi nyl alcohol and in polymers derived from polyvinyl alcohol (Celanese, 2000). Hence the manufacturing of polyvinyl alcohol is not relevant in the context of residual monomer content.

Use pattern of vinyl acetate:

Main category Industry category Use category Non dispersive use Chemical industry: used in synthesis (IC 3) Intermediate: monomer in the production of polyvinyl acetate (UC 33)

CAS No.: 108-05-4 18R059_0505_envDraft of 04.05.2005Table 2-2:Vinyl acetate in the value chain: (co)polymers are usedin a wide spectrum of products (Wacker-Specialities, 2002)

Building material Printing ink Paint Film Lacquer Adhesive Cosmetic, hairspray Plastic Paper finishing Textile finishing Non

wovenVAM+VAMÆpolyvinyl acetatexxxxxxxxVAM+acrylateÆvinyl acrylic co-polymerxxxxxVAM+ethyleneÆEVAxxxVAM+ethyleneÆVAExxxxxxxVAM+vinyl chlorideÆVC copolymerxxxxxxVAM+carbonic acidÆVA carbonic acid copolymerxVAM+vinyl esterÆVA vinyl ester copolymerxxxCAS No.: 108-05-419R059_0505_env Draft of 04.05.2005

3 ENVIRONMENT

3.1 ENVIRONMENTAL EXPOSURE

3.1.1 General discussion

3.1.1.1 Releases into the environment
Vinyl acetate is used as an intermediate in th e production of a range of polymeric materials. Releases of the monomer into the environmen t may be expected during various life cycle stages and from the final products and articles generated from VAM (cf. chapter 2.1 ). VAM is a comparatively volatile substance that is likely to evaporate into the atmospheric compartment, primarily via off-gas. Likewise, owing to the high water solubility of VAM, emissions may occur to the aqueous phase if the substance is getting into contact with water. Waste water may in turn be a relevant s ource for emissions to the atmosphere during treatment (e.g. stripping).

3.1.1.1.1 Production of the monomer
Vinyl acetate is produced by a catalytic reacti on of ethylene and acetic acid. All commercial producers of vinyl acetate communicated closed system facilities in a largely continuous process. Nevertheless, start-up, shut-down and purification operations may result in some releases of VAM to waste products. Incine ration of waste was reported by all but one producer, flue gas is commonly flared, and waste water typically undergoes a distillation procedure in order to regain the dissolved m onomer. Measured values of VAM in waste water discharges from closed production systems show that losses can be significantly reduced by an adequate process design including pre-treatment of the waste water.
The aggregated capacity of the five vinyl acet ate production facilities identified across the EU amounts to approximately 800,000 tonnes per annum (chapter 2.1.1.2 ). Specific emission data for releases of VAM to water and air have b een provided by all producers. The figures are set out in Table 3-1 below.

From combined measured and estimated data it is concluded that emissions to surface water from production totalled approximately 0.486 t/a while emissions to air accounted for about 218 t/a.

CAS No.: 108-05-4 20R059_0505_env Draft of 04.05.2005
Table 3-1: VAM releases from production to the aquatic and atmospheric compartment

Site Production (t/year) Release to surface water (kg/year) Comment Direct release to atmosphere (kg/year) Comment

4 110,000 < 331 water treated within process (distillation) and then discharged to biological WWTP; concentration below d.l. of 50 μg/l 367 below d.l., figure communicated by company

21 200,000 < 155 emission to biological WWTP provided - incineration

22 100,000 < 0.36 water treated within purifying unit and external WWTP; calculated from d.l. of 0.1 mg/l and site-specific data - incineration

26 140,000

- water is treated within process (distillation, no STP); no VAM detected in waste water* 217,500 figure communicated by company

27 250,000

- plant designed to reduce emissions (no STP)** - waste gas from routine venting is flared

Σ 800,000 t/year 486.36 kg/year 217,867 kg/year * The waste water is treated within the process by distillation (no STP) and sent to a collection basin where organic compounds are measured before release to a waste water discharge canal and then to a river. Organic compounds are mostly acetates and acetal dehyde. No VAM is detected in th e discharge (detection limit of < 1 ppm by ionic chromatography). Any residual VAM molecules are assumed to hydrolyse completely at a pH of 12 in the waste stream. ** The company operating the plant reported that new technology had been implemented in the recently commissioned facility in order to contain and recover VAM in the process (closed system process, distillation of wastewater for re-introduction of material in the process, incineration of remaining waste).

3.1.1.1.2 Processing of vinyl acetate monomer

Table 2-2 shows the most common (co)polymers ge nerated from VAM. It could not be elucidated for all processing sites, which notified being "users" of VAM in the CEFIC questionnaire, what kind of operations they actua lly perform. If not i ndicated otherwise, the term “use” or “processing” of VAM was interpreted as polymerisation of the monomer. Roughly, three types of processors can be distinguished:

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 a few large-scale facilities which manufacture (co)polymers from VAM for resale

 some small- to medium-scale (SMC) facilities polymerising for captive use, e.g. manufacturers of paints, coatings or fibre

 the majority of SMC facilities which do not perform polymerisation but purchase VAM (co)polymers for compounding, i.e. mixi ng of vinyl acetate (co)polymers with e.g. fillers, binders and other polymeric dispersions

A default emission factor for waste water of 0.7 % of the annually processed volume is provided in the TGD for intermediates in chemical synthesis. The emission factor foreseen in the TGD is not considered representative fo r vinyl acetate and replaced by a more specific value of 0.02 %, which was communicated by indus try representatives at a technical meeting 5 in 2002. The factor of 0.02 % is backed by the av ailable site-specific data. The majority of facilities emitted less than 0.01 %, many even le ss than 0.001 % of their tonnage to waste water. Three sites emitted between 0.01 and 0.02 % of their tonnage, while only two exceeded the latter value. The highest emission fact ors were 0.04 and 0.15 %. The value of 0.02 % provided by industry is therefore assumed to be a realistic factor for estimating emissions.
Unlike for some of the SMC facilities, waste gas from routine venting is typically collected and flared in large operational sites. If no sp ecific data were provided by the companies, it was assumed that 0.1 % of the polymerised materi al is being released to the atmosphere as VAM, which is the default emission factor fo r air provided in the TGD. The rapporteur considered to extrapolate information from the av ailable site specific data in order to obtain a more representative fraction of release to air. The site specific emission factors ranged from less than 0.01 % to 0.5 %. Most facilities emitte d between 0.01 and 0.1 % of their tonnage to air. The fraction of 0.1 % foreseen in the T GD is therefore considered a realistic and conservative value for estimating releases to air.

Table 3-2: VAM releases from processing sites to the aquatic and atmospheric compartment

Site Processing (t/year) Release to surface water (kg/year) Comment Direct release to atmosphere (kg/year) Comment

1 30,000 15.8 calculated from d.l. of 50 μg/l, specific STP flow 430 figure provided by company in CEFIC questionnaire
2 10,000 1550 d.l. of 10 μg/l specific STP flow 2,630 from CEFIC questionnaire
3a 6,000 100.2 calculated from given effluent concentrations 28,000 from CEFIC questionnaire

5 As agreed on TM III’02, a technical meeting with i ndustry took place in Frankfurt, Germany, in October 2002 to further the discussion on information and data to be included in the exposure scenario.

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Site Processing (t/year) Release to surface water (kg/year) Comment Direct release to atmosphere (kg/year) Comment

3b
3c
3d 10,000 8,000 4,000 and STP default values

5 90,000 331 see production site 4 ( Table 3-1 ) 367 from CEFIC questionnaire
6 25,000 22.2 calculated from annual emission to waste water and STP flow 11,100 from CEFIC questionnaire

7* 10,810 3 generic calculation 7,110 aggregated data provided by CEPE max. value given mean: 1126 kg/a
8 15,000 230 annual emission to waste water, specific STP flow 31,000 from CEFIC questionnaire

9 9,100 5 annual emission to waste water, specific STP flow 14,000 from CEFIC questionnaire

10 15,000 1.13 annual emission to waste water, specific STP flow 14,000 from CEFIC questionnaire

11 110,000 84.5 d.l. of 5.7 μg/l and STP flow - incineration

12 36,000 720 no specific data on emissions but on STP flow 7,500 worst case scenario for diffuse releases, below d.l. at waste gas incinerator
13 280 - no water involved in process 280 estimate based on release of 1 kg/t

14 2,000 40 generic calculation 2,000 from CEFIC questionnaire
15 2,200 6.5 annual emission to waste water, specific STP flow 1,500 from CEFIC questionnaire

16 400 - no water involved in process 70 from CEFIC questionnaire

17 300 6 generic calculation 400 from CEFIC questionnaire
18 14,000 10 annual emission 8,000 from CEFIC

CAS No.: 108-05-4 23R059_0505_env Draft of 04.05.2005
Site Processing (t/year) Release to surface water (kg/year) Comment Direct release to atmosphere (kg/year) Comment

to waste water, specific STP flow questionnaire

19 25,000 249 annual emission to surface water, specific STP flow 7,000 from CEFIC questionnaire

20** 0 0.1 annual emission to waste water 1 pers. commun.

23 17,000 - pers. commun. < 1.05E-05 pers. commun.
24 5,000 225 calculated from d.l. of 5 mg/l and effluent flow from process 24,925 pers. commun.

25 6,910 138 generic calculation 3,500 pers. commun.

28 8,000 160 generic calculation 8,000 estimate based on release of 1 kg/t
29 6,500 7.5 annual emission to waste water, specific STP flow 200 pers. commun.

30 8,400 1.39 calculated from given effluent concentrations and STP flow - pers. commun.

Σ 474,900 t/year 3,906 kg/year 172,013 kg/year * Aggregated data. The processing volume of 10,810 t/a in the table refers to the two companies still conducting polymerisation of VAM themselves. The total volume of ready to use VAM polymers in manufacture, however, added up to 43,524 tonnes in 2000. The magnitude of emissions in relation to total VAM use was specified as a maximum of 30 kg/year to waste water treatment plants, and a maximum of 7,110 kg/year to air by industry association CEPE. ** confirmation of conducting merely compounding ope rations, i.e. handling of the (co)polymers As the difference of 325,000 t/a between nominal production volume (800,000 t/a) and verified processing capacities (total of 475,000 t/a) is rath er high, a generic worst case scenario is included in the risk assessment to estimate the fraction of release at the local main source. The estimate is based on:

 a fraction of main source of 0.15 (Tab. B3.2 of TDG)

 a duration of emission of 300 d (Tab. B3.2 of TDG)

 a waste water flow of 10,000 m 3 /s and a dilution of D = 40

 an emission factor to waste water of 0.02 % for processing (personal communication, technical meeting with industry representatives in 2002)

 a release fraction of 0.1 % of the polymerised material to air (as VAM) For the local main source, a release of 9.75 t/a to waste water, of 975 kg/a to surface water, and of 48.75 t/a to the atmosphere is calculated.

CAS No.: 108-05-4 24R059_0505_env Draft of 04.05.2005 For the whole processing volume of 325,000 t/a, a re lease of 65 t/a to waste water, of 6,5 t/a to surface water and of 325 t/a to the atmosphere is derived.

3.1.1.1.3 Compounding and use of materials cont aining vinyl acetate (co)polymers
Finished (co)polymers contain various concen trations of VAM residuals. Owing to the high volatility of VAM, it is anticipated that thes e residuals are exhaustively released during further life-cycle stages down the supply ch ain such as compounding into ready-to-use products.
Further diffusive releases from end-use pr oducts during service lifetime (e.g. adhesives, paints, fillers, coating materials, plasters and primers for porous building materials in the construction industry and in finishing agents ; Ullmann, 1998) are expected to be low. Nevertheless, a contribution of these products to regional background concentrations was considered. Assuming that (co)polymers have on average a VAM content of 3,000 ppm (cf. section 2.2 ), the diffusive emissions may amount to 3,000 t/a based on a VAM market supply of roughly 1,000,000 t/a (cf. section 2.1.1.2 ). To estimate the fractional release to air and water, the fugacity of VAM was calculated (cf. Table 3-6 ): accordingly, 2,700 t/a (90 %) were assumed to be released to air while 300 t/a (10 %) would enter the aquatic compartment.
Polyvinyl alcohol is produced by trans-esterfica tion (saponification) of vinyl acetate (co)polymers. After this additional processing step, resi dual VAM will not be present in the finished product. Therefore, releases of VAM fr om polyvinyl alcohol were not estimated.

3.1.1.1.4 Storage and Transport
Gaseous releases of VAM could occur during storage and transport of the substance due to its high vapour pressure. However, a contribution to air emissions of these operations was not assumed because the use of supposedly closed -system containers and storage systems was reported. Furthermore, no tool is currently ava ilable to estimate the fractions which might be released during storage and transport despite the taken precautionary measures.

3.1.1.2 Degradation in the environment

3.1.1.2.1 Degradation in the atmosphere

Direct photolysis Vinyl acetate molecules do not absorb light at wavelengths longer than 250 nm (Daniels, 1983). As solar irradiation wavelengths in the troposphere exceed 290 nm, no direct phototransformation of VAM is expected to occur in this layer of the atmosphere.

Indirect photolysis VAM undergoes rapid photooxidative transformation in air. It predominantly reacts with hydroxyl radicals and to a minor extent also with ozone by addition to the olefinic moiety.
Calculations were performed with the AOPWIN TM (v1.91) computer program based on experimentally determined rate constants both for OH-radicals and ozone (cf. Appendix).

CAS No.: 108-05-4 25R059_0505_env Draft of 04.05.2005 Based on a mean atmospheric concentration of [OH] = 5 x 10 5 cm -3 and an overall OH rate constant of 26.3 x 10 -12 cm 3 molec -1 s -1 (Atkinson et al., 1982), an atmospheric half-life of 14.6 hours is estimated for VAM. Assu ming a rate constant of 25 x 10 -12 as included in the AOPWIN TM Experimental Database (Saunders et al., 1993), an atmospheric half-life of 15.4 hours results. The OH rate constant of 26.3 x 10 -12 cm 3 molec -1 s -1 and estimated atmospheric half-life of 14.6 hours were used in the risk assessment.

From a mean ozone concentration of 7 x 10 11 cm -3 , a half-life of 6.55 days is derived.

Table 3-3: Reactivities and half-lives for phototransformation of VAM in the troposphere

Oxidative species Species concentration Rate constant (cm 3 molec -1 s -1 ) Half-life (days) Source

OH radicals 5.0E+05 cm -3 26.34E-12 0.608 (e) Atkinson et al. (1982)
OH radicals 5.0E+05 cm -3 25.00E-12 0.642 (e) Saunders et al. (1993)
Ozone 7.0E+11 cm -3 17.50E-19 6.55 (e) Atkinson et al. (1982)
Ozone 4 - 8 ppm 3.2 ± 0.47E-18 2 (m) Grosjean and Grosjean (1998)
NO x 0.2 - 2.0 ppm 0.2 - 0.3 (m) Joshi et al. (1982) (e) = estimated (m) = measured value

In smog chamber experiments with NO x concentrations simulating rural and urban atmospheres, photooxidative half-lives of VAM were determined to 4.1 ± 0.1 and 6.5 ± 3.0 hours, respectively (Joshi et al., 1982) . The initial VAM concentration was 4 ppm (v/v) while NO x levels were either 0.2 ppm (v/v) or 2 ppm.

3.1.1.2.2 Degradation in the aquatic compartment

Abiotic degradation VAM undergoes hydrolysis in surface and groundwat er. A hydrolytic half-life of 7.3 days at pH 7 and 25 °C was estimated for the compound (Mabey and Mill, 1978). From this value, a half-life of 17 days can be derived for a ge neric environmental temperature of 12 °C, as foreseen in the TGD. As pH decreases, the hydr olysis rate decreases and half-life increases. Main hydrolysis products of VAM are acetic acid and acetic aldehyde (Daniels, 1983; Stuckey et al., 1980).
Half-lifes of VAM in basic and acidic aquatic environments could not be obtained. However, hydrolysis rate constants were determined for VAM residuals in water-based dispersion paints, having typically an alkaline pH of 8 – 9. One paint was acidified to pH of 5.5 in order to determine the rate constant in an acidi c solution. At pH 8.6, the half-life of VAM was found to be less than 4 days at room temperature, and a rate constant of 1.68 l mol -1 s -1 was experimentally determined. At a pH of 5.5, hydrol ysis was found to be distinctly slower with a rate constant of 0.002 l mol -1 s -1 (kinetic data provided by industry, 2002). The observed

CAS No.: 108-05-4 26R059_0505_env Draft of 04.05.2005 hydrolysis rates in water-based and dispersion pain ts give further indication that hydrolysis of VAM decreases with pH, but cannot be transferred to aquatic environments.
The estimated half-life of 17 days at standard environmental parameters (pH 7 and 12 °C) is used in the risk assessment of VAM.

Biodegradation
In an initial degradation step, VAM is enzy matically hydrolysed to acetate and acetaldehyde, followed by either mineralization or biotranformation into biomass. Based on a Ready Biodegradability Modified MITI Test I (OECD test guideline 301 C), measuring the mineralization of a test subs tance on the basis of oxygen consumption, vinyl acetate is classified as readily biodegradable (Chemicals Inspection and Testing Institute (Ed.), Japan, 1992). In the test, a biodegradati on rate of 82-98 % was observed by BOD after a test period of 14 days and using non-adapte d, activated sludge under aerobic conditions (pH 7, temperature 25 ± 1 °C, concentration of test substance at test begin: 100 mg/l).
The results of several other laboratory studi es also demonstrate that VAM is readily biodegraded by domestic sewage effluent mi croorganisms both under aerobic (e.g. Pahren and Bloodgood, 1961; Price et al., 1974) and anaer obic conditions of sludge digesters (e.g. Chou et al., 1979; Stuckey et al., 1980). Although the tests were not conducted according to standardized test guidelines, they provide fu rther evidence for the above classification as readily biodegradable.
In a more recent study (Nieder et al., 1990) it wa s demonstrated that VAM is biotransformed in samples of soil sludge and sewage under aer obic and anaerobic conditions. Four yeasts and 13 bacteria feeding aerobically on VAM were is olated. Rates of transformation were higher under aerobic conditions, but anaerobic and aerobi c degradation pathways both yielded the same products, i.e. acetaldehyde as an intermed iate and acetic acid as a final product. An aerobic transformation half-life of 12 hours was obt ained with one of the bacterial isolates, whereas a half-life of 60 hours was found for the non-enzymatic hydrolysis in a sterile medium.

No tests are available that simulate the biode gradation of VAM in surface waters. Therefore, the rate constant and half-life for biodegradati on in surface waters has to be derived based on the results from the available screening tests. For readily biodegradable substances a rate constant of 0.047 d -1 that is equivalent to a half-lif e of 15 d is proposed in the TGD ( Table 3-4 ).

3.1.1.2.3 Degradation in soil and sediment
Vinyl acetate is also transformed by biotic and abiotic hydrolysis in soils and sediments. As described in the preceding section, microbial isolates from sludge and soil were found to be capable of utilizing VAM as a sole carbon source (Nieder et al., 1990).
There is evidence that some soil organisms ar e also capable of decomposing polymers of vinyl acetate. In an aqueous test medium c ontaining 4.5 g/l of polyvinyl acetate as the sole carbon source, the polymers were biotransformed by oil fungi during an incubation period of 15 days at room temperature (Garcia Trejo, 1988). It should be noted, however, that deCAS No.: 108-05-4 27R059_0505_env Draft of 04.05.2005 polymerisation is assumed to be the limiting st ep. Further biodegradation is rapid so that relevant VAM concentration in environmental compartments are not to be expected.
Biodegradation rate constants were derived fo r the different environmental compartments according to section 2.3.6.5 of the TGD, base d on the ready biodegradability of VAM as shown in a number of studies and a Kp soil < 100. The rate constants are compiled in Table 3-4 below.

Table 3-4: Biodegradation rate constants of VAM in different environmental compartments
Compartment Biodegradation rate activated sludge (STP) k STP = 1 h -1

surface water k SW = 0.047 d -1

sediment k sed = 0.00231 d -1

soil k soil = 0.023 d -1

3.1.1.3 Distribution
No information on transport and partitioning of VAM between different environmental media was found in the available literature or was provided by industry. The distribution of the compound between air, water, sediment, and soil compartments following release to the environment was therefore assessed based on the physical and chemical properties of VAM.

3.1.1.3.1 Adsorption
Measured data on adsorption and desorption of VAM to soil or sediment could not be obtained. However, given an octanol - water partition coefficient of log K ow = 0.73, it is concluded that VAM has only a low potential to adsorb to soils or sediments.
Using the QSAR regression equation given in the TGD for non-hydrophobic substances, an organic carbon - water partition coefficient of K oc = 24.2 l/kg was calculated from the log K ow . Further solid - water partition coefficients (K p ) were derived from this K oc for the various environmental compartments by using the generi c values given in the TGD for organic carbon contents of soils and sediments (cf. Table 5, section 2.3.4 in the TGD).

CAS No.: 108-05-4 28R059_0505_env Draft of 04.05.2005
Table 3-5: Partition coefficients of VAM for various compartments, derived according to the standard environmental characteristics of the TGD

Compartments Partition coefficients (l/kg)
soil – water Kp soil = 0.484
sediment – water Kp sed = 1.211 suspended matter – water Kp susp = 2.421 activated sludge – water Kp sludge = 8.958
raw sewage – water Kp sewage = 7.263

3.1.1.3.2 Volatility
Given the high vapour pressure of VAM and a Henry's law constant of H = 51.6 Pa m 3 mol -1 (at 20 °C), a relevant transfer from the aqueous to the atmospheric compartment is expected. This transfer is mainly caused by volatilisati on and air stripping during treatment of waste water, and to a lower degree by volatilisation from surface waters. The transfer to the atmosphere is to some extent counterbalan ced by the high water solubility of the compound. Based on the Henry's law constant, VAM can be regarded as a moderately volatile compound.

3.1.1.3.3 Modelling of distribution
The (steady state) distribution of VAM betw een various environmental compartments at 12 °C was estimated by means of the Mackay level 1 six compartment fugacity model, employing the EQC Model v.1.0 and the physico-chemical data compiled in Table 1-1 . The output, as shown in Table 3-6 , indicates that the major environmental compartment for VAM is air, with a smaller proportion entering th e aqueous compartment and just negligible quantities being predicted for other compartments.

Table 3-6: Mackay level 1 environmental distribution of vinyl acetate calculated from the OECD EQC model v.1.0 at 12 °C
Compartments Distribution (%)
air 91.5

water 8.4
soil 0.037
sediment < 0.001 suspended sediment < 0.001
fish < 0.001

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3.1.1.3.4 Elimination in Sewage Treatment Plants (STP)
The fraction of VAM degraded in a municipal st andard STP as well as the distribution of the residual VAM leaving the STP was estimated from SIMPLETREAT 3.0. Calculations were performed using the partition coefficients Kp sludge = 8.958 l/kg, Kp sewage = 7.263 l/kg and a first order biodegradation rate constant for VAM in a STP of 1 h -1

.

Table 3-7: Modelled fate of vinyl acetate in a standard municipal STP, according to the provisions of section 2.3.7 of the TGD

Fraction Percent

directed to air 11.6 directed to sludge 0.2 degraded 78.2
total removal from waste water 90.0
directed to water 10.0

3.1.1.3.5 Accumulation

Bioaccumulation test results of VAM are not av ailable. However, as a result of the high vapour pressure, ready degradability and low li pophilicity of the substance, it is neither expected to bioconcentrate in terrestrial or aquatic organisms, nor to biomagnify in food chains. This appraisal is further backed by results from QSAR calculations (BCFWIN v.2.14) which give a BCF of 3.16 (log BCF = 0.50) based on a log K ow = 0.73 of VAM.

Geoaccumulation of VAM is not expected, based on a K oc value of 24.2 l/kg along with effective biotic and abiotic breakdown pr ocesses in soil, hydrolysis and ready biodegradability in water, and rapid photooxidative breakdown of VAM in the atmosphere.

3.1.2 Exposure Assessment for the Aquatic Compartment
Exposure of the aquatic compartment to VAM may result from the production of VAM, from the polymerisation of the monomer, from co mpounding of polymer-containing formulations and eventually during subsequent use of the products. Water is generally involved in the stages of VAM production and consecutively VAM polymerisation as well as cleaning of the systems. In polymeric material, the residual m onomer concentration decreases rapidly due to “outgassing”. As the average VAM content in (co)polymers is assumed to be 3,000 ppm, it can be concluded that diffusive releases fr om end-use products will be a major exposure pathway. However, as the major amount of the re sidual monomer material will be released in the early stages of product lifetime, releases to the aquatic compartment after disposal to landfills is assumed to be relatively low compared to production and processing point sources.
Local point emission sources of VAM for th e aqueous compartment can be roughly grouped into three categories:

CAS No.: 108-05-4 30R059_0505_env Draft of 04.05.2005

 large-scale production and/or polymerisation of the monomer

 medium-scale sites which comprise polymerisation of VAM and compounding

 compounding operations

While there exist few large scale producers and/ or polymerisers, the number of medium-scale polymerisers and notably compounders is considerably higher. An increasing lack of knowledge about VAM emissions down the supply ch ain has to be noticed. To this end the final destination of hundred thousands of tonne s of VAM produced or imported into Western Europe could not be elucidated within the scope of this report.

3.1.2.1 Estimation of local environmental concentrations (C local water )
In general the local concentrations in water we re calculated using the approach outlined in the TGD (section 2.3.8.3) and the corresponding annexe s (A- and B-tables). The calculations involved the following steps:

(1) Emission per day : Derivation of the local daily emission rates (Elocal water ), based on emission data provided by industry or default values from the TGD. (2) Influent concentration : Conversion of the local emission rate to a concentration in untreated waste water (Clocal infl ) by the effluent volume (default of 2,000 m 3 /day or 10,000 m 3 /day depending on tonnage, or site-specific data). (3) Effluent concentration : Calculation of the concentr ation in the STP effluent (Clocal effl ) assuming a remaining fraction of 0.1 (90 % removal rate according to SIMPLETREAT calculation) of the infl uent going to the STP effluent. (4) Concentration in surface water : Derivation of the local concentration in the aqueous compartment from the equation Clocal water = Clocal effl / D, with D = 10 or D = 40 depending on tonnage, or specific dilution factors supplied for the individual site. (5) Average annual concentration in surface water : The average annual concentration was derived by multiplication of Clocal water by X/365, yielding Clocal water_annual , with X being the specific number of opera tion days per annum or a generic value of T emission = 300 days. (6) PEClocal : The PEClocal water was derived by adding the PECregional water to the calculated value of Clocal water , with PECregional water being taken from Simplebox calculations (see Appendix 4). (7) Average annual PEClocal water_ann : This parameter was derived by addition of PECregional water to the calculated value of Clocal water_annual
.

3.1.2.1.1 Production of the monomer
VAM is manufactured in closed systems at el evated temperature and pressure. Fractional distillation is applied to separate different c onstituents from the waste water and recuperate VAM to enhance reaction yields. Hence VAM concentration in waste water of production

CAS No.: 108-05-4 31R059_0505_env Draft of 04.05.2005 facilities is generally low. Site-specific data were made available from all VAM producers by providing figures either on annual loads to waste water or surface water or measured concentrations in waste water (cf. Table 3-8 ).
All producers of VAM are either located at larg e rivers, estuaries, or at the sea. Hence dilution of the waste water is high. Leaving as ide shut-downs for reasons of maintenance work, continuous production was reported by all VAM manufacturers.

Table 3-8: Emissions to water from production sites of VAM in the European Union

Site Productio

n (t/year) Release to STP (kg/year) Release to surface water (kg/year) Clocal water ( μ g/l) Specific information provided/used
4 110,000 3.31E+03 < 3.31E+02 < 2.09E-01 effluent concentration below d.l. of 50 μg/l; STP effluent flow and dilution data
21 200,000 1.55E+03 <1.55E+02 6.80E-02 emission load, STP effluent flow and dilution data
22 100,000 3.60E+00 3.60E-01 4.00E-03 effluent concentration below d.l. of 0.1mg/l; STP effluent flow data
26 140,000 no STP* - - effluent concentration below d.l. of 1mg/l; at pH 2 VAM hydrolyses completely in the waste stream 27 250,000 no STP** - - TOC of waste water, dilution data
Σ 800,000 t/year 4.86E+03 kg/year 4.86E+02 kg/year * The waste water is treated within the process by distillation (no STP) and sent to a collection basin where organic compounds are measured before release to a waste water discharge canal and then to a river. No VAM is detected in the discharge (detection limit of < 1 ppm by ionic chromatography). Any residual VAM molecules are assumed to hydrolyse complete ly at a pH of 12 in the waste stream. ** The company operating the plant reported that new technology had been implemented in the recen tly commissioned facility in order to contain and recover VAM in the proce ss (closed system process, distillati on of wastewater for re-introduction of material in the process, incineration of remaining waste).

3.1.2.1.2 Processing of the monomer

Release from point-sources: verified processing sites
An emission factor for wastewater of 0.02 % was used in the calculations for the aquatic compartment if no site-specific emission da ta were provided (personal communication, technical meeting with industry representatives in 2002, cf. section 3.1.1.1.2 ).
Where no site-specific information on the flow ra te of the STP or the receiving water course was given, the generic scenario of the TGD was applied: For low production volume facilities ( ≤ 1000 t/a), a domestic treatment plant s cenario with a flow rate of 2,000 m 3 /d and a dilution factor of 10 in surface water was assumed, whereas a flow rate of 10,000 m 3 /d and a dilution

CAS No.: 108-05-4 32R059_0505_env Draft of 04.05.2005 factor of 40 was assumed for high production volume facilities 6 . Most operators, however, provided specific data which were used in the calculations.

Pretreatment of raw waste water is common practice, e.g. by adding special zeolites or by electroflotation. The solid phase is subsequently removed (e.g. with a filter press), while the pre-purified waste water is sent to a municipal ST P for further treatment. It is expected that at least 50 % of the residual VAM in waste water is retained with the filter cake. A preliminary purification step can therefore substantially re duce the content of total organic carbon in the waste water. Regarding the reported site-specifi c emissions or concentrations in waste water that were used in the exposure calculations, it is assumed that any internal pre-treatment is already reflected in the figures provided, if not indicated otherwise.
In few cases, VAM production and polymerisa tion were conducted at the same location, although not necessarily by one single company. If so, the individual emissions of both operations were added up to calculate one co mbined local concentration in the receiving surface water.

Table 3-9: Emissions of VAM to surface water from processing (polymerisation) sites of VAM in the European Union (fibre industry and paint/coating industry excluded)

Site Processing (t/year) Release to STP (kg/year) Release to surface water (kg/year) Clocal water ( μ g/l) Specific information provided/used

1 30,000 1.58E+02 1.58E+01 4.81E-04 calculated from d.l. of 50 μg/l, STP effluent flow, dilution
2 10,000 1.55E+04 1.55E+03 6.60E-02 calculated from d.l. of 10 μg/l, STP effluent flow, dilution
3a 6,000 6.00E+02 6.00E+01 1.00E+01 calculated from d.l. of 100 μg/l
3b 10,000 3.00E+02 3.00E+01 5.00E-01 effluent concentr. of 50 μg/l
3c 8,000 2.40E+01 2.40E+00 4.00E-01 effluent concentr. of 4 μg/l
3d 4,000 7.80E+01 7.8E+00 1.3E+00 effluent concentr. of 13 μg/l

5 90,000 3.31E+03 3.31E+02 2.09E-01 calculated from d.l. of 50 μg/l, STP effluent flow, dilution
6 25,000 2.22E+02 2.22E+01 3.04E+00 calculated from emission to waste water, dilution 7* 10,810 3.00E+01 3.00E+00 5.00E-01 generic calculation
8 15,000 2.30E+03 2.30E+02 2.30E+00 emission to waste water, STP effluent flow
9 9,100 5.00E+01 5.00E+00 9.81E-01 emission to waste water, STP effluent flow

6 default values according to emission scenario document for IC-3 (chemicals used in synthesis, TGD part IV)

CAS No.: 108-05-4 33R059_0505_env Draft of 04.05.2005
Site Processing (t/year) Release to STP (kg/year) Release to surface water (kg/year) Clocal water ( μ g/l) Specific information provided/used

10 15,000 1.13E+01 1.13E+00 3.10E-03 emission to waste water, STP effluent flow
11 110,000 8.45E+02 8.45E+01 1.32E-01 calculated from d.l. of 5.7 μg/l, STP effluent flow, dilution
12 36,000 7.20E+03 7.20E+02 2.10E+00 STP effluent flow, dilution
13 280 0.00E+00 0.00E+00 0.00E+00 no water used in process

14 2,000 4.00E+02 4.00E+01 7.69E+00 generic calculation
15 2,200 6.50E+01 6.50E+00 1.03E+01 emission to waste water, STP effluent flow, dilution
16 400 0.00E+00 0.00E+00 0.00E+00 no water used in process
17 300 6.00E+01 6.00E+00 1.16E-05 generic calculation
18 14,000 1.00E+02 1.00E+01 1.27E+00 emission to waste water, STP effluent flow
19 25,000 2.49E+03 2.49E+02 9.61E+00 emission to surface water, STP effluent flow
20** 0 1.00E+00 1.00E-01 1.91E-07 emission to waste water

23 17,000 0.00E+00 0.00E+00 0.00E+00 no emission to waste water

24 5,000 2.25E+03 2.25E+02 7.23E-03 calculated from d.l. of 5 mg/l, STP effluent flow, dilution
25 6,910 1.38E+03 1.38E+02 2.67E-05 generic calculation
28 8,000 1.60E+03 1.60E+02 1.33E+00 generic calculation
29 6,500 7.50E+01 7.50E+00 2.03E-03 emission to waste water, STP effluent flow, dilution
30 8,400 1.39E+01 1.39E+00 1.78E-03 emission to waste water, STP effluent flow, dilution
Σ 474,900 t/year 39,063 kg/year 3906 kg/year * The processing volume of 10,810 t/a in the table refe rs to the two companies still conducting polymerisation of VAM themselves. The tota l volume of ready to use VAM polymers in manufacture, however, added up to 43,524 tonnes in 2000. The magnitude of emissions in relation to total VAM use was specified as a maximum of 30 kg/year to waste water treatment plants by industry association CEPE. ** confirmation of conducting merely compounding ope rations. i.e. handling of the (co)polymers

CAS No.: 108-05-4 34R059_0505_env Draft of 04.05.2005 Release from point-sources: non-verified generic site

Based on a difference of 325,000 t/a between nominal production volume (800,000 t/a) and verified processing capacities (total of 475,000 t/a), a generic scenario was calculated for the local main source (fraction of main source = 0.15, cf. section 3.1.1.1.2 ). A release of 9.75 t/a to waste water, of 975 kg/a to surface water and a Clocal water of 8.12 μg/l are derived.

Release from diffuse sources

A quantitative breakdown of the use pattern of VAM is a difficult task to perform since the notified annual production volume in Wester n Europe (800,000 t/a) considerably exceeds that of the verified industrial uses (475,000 t/a). For a conservative estimate of the diffusive releases from end-use products during service lifetime, a VAM total market supply of about 1,000,000 t/a and an average VAM content of 3,000 ppm in (co)polymers is assumed, leading to an estimated total release of 3,000 t/a, with a fractional release of 300 t/a (10 %) directed to the aquatic compartment (cf. section 3.1.1.1.3 ).

3.1.2.1.3 Manufacture of synthetic fibres
According to information provided by the indus try association of European Fibre Producers CIRFS ( C omité I nternational de la R ayonne et des F ibres S ynthetiques) in the CEFIC questionnaire of 2000, seven sites in five differe nt countries (including Turkey) were using VAM in the manufacture of acrylic fibres at approximately 60,000 t/a. With a share of around 25 % accounting for Turkey, 45,000 t/a were processed at Western Europe sites.
More recent data provided by CIRFS in 2004 rev eals that acrylic fibre production in the EU takes place at four sites with a combined capacity of up to 28,000 t/a (sites 3a-3d, Table 3-9 ).
VAM is used in the production of acrylic fibr e strands in proportions of less than 10 % by weight in the finished product. The filaments are coagulated and subsequently stretched in wet processes, thereby leaving some VAM in the process water. Reportedly, the process water is circulated in closed loop systems a nd finally discharged. All following calculations are based on site-specific effluent concentrations and default values for STP effluent flow and dilution.
Emissions from downstream manufacturing are "none or very low" according to the information provided by CIRFS in 2000.

3.1.2.1.4 Manufacture of coatings and printing inks
As communicated by industry association CEPE ( C onseil E uropéen des Industries des P eintures, E ncres d’Imprimerie et Couleurs d’Art) , most of the manufacturers buy polymer emulsions (PVA) ready for use in paints and do not polymerise VAM by themselves.

CAS No.: 108-05-4 35R059_0505_env Draft of 04.05.2005 According to a questionnaire launched by CEPE in the year 2000, 52 companies used vinyl acetate polymers (PVA) at 116 different sites in the EU for making printing inks, paintings and coatings. The total quantity of processe d polymers added up to 43,524 tonnes, of which 40,419 tonnes were used in water-born products. Th e largest volume of PVA used on one site was 8,900 tonnes (figure for 2002).
According to information provided by CEPE in 2003, only two companies still conducted polymerisation of VAM in the EU in 2002, at one single site each. Reported annual volumes were about 7,120 tonnes and 3,690 tonnes, re spectively (combined capacity of 10,810 tonnes).
For reasons of confidentiality only ranges of pr ocessed PVA volumes and arithmetic means of emission data have been provided by CEPE rather than specific values of individual sites. Absolute quantities of VAM emissions to water were reported by CEPE to be in a range of 0 - 30 kg/a (mean of 2 kg/a). Related to the site-specific processed VAM volumes, the emissions to water were between 0 - 2 ppm, at a mean of 0.7 ppm. Employing the generic values tabled below, a local concentration of Clocal water = 0.5 μ g/l is predicted from a reported max. annual emission to waste water of 30 kg (site 7 in Table 3-9 ).

Table 3-10: Parameters used in calculation of Clocal water for a coatings and printing inks site

Parameter Figure Source

Maximum annual emission to waste water 30 kg/a provided by CEPE in 2002
Operation 300 days * TGD default, B 3.9

STP effluent flow 2,000 m3/d TGD default

Dilution factor 10 TGD default
* Albeit the number of days where batches containi ng VAM polymers being manufactured were reported to cover a span of 4 to 365 days per year (mean 127 d/a) it could not be elucidated if continuous operation (= 365 d/a) can be attributed to the highest volume.

According to CEPE, waste water from the ma nufacturing plants handling the vinyl acetate monomer is typically treated on-site to remove solids (oligomers) prior to discharge to a municipal waste water treatment plant. Measured VAM concentrations after this pretreatment were reported in a range of 1 - 10 μ g/l, at a mean of 6 μ g/l. If the highest measured concentration of 10 μ g/l is chosen for calculation (instead of a maximum annual emission of 30 kg) and assuming a 90 % removal rate and a d ilution factor of 10 in the receiving river, a local concentration of Clocal water = 0.1 μg/l was calculated for surface waters. However, the above given Clocal water of 0.5 μ g/l was used as a worst case value for the risk characterization for coatings and printing inks manufacturers (no. 7). Typical conten ts of VA polymers in paints and inks span a broad range of 0.6 % up to 60 %, averaging 18 %. As notified by 53 manufacturers of paints and inks, the VAM resi duals in their products range from 0.0003 % to 0.2 %, averaging 0.07 % (aggregated data, CEPE 2000). In the process of incorporating the polymer emulsions into the paint product, however, it can be expected that the residual VAM content is decreased due to evaporation or hydr olysis into acetic acid and acetaldehyde. At an alkaline pH of 8 – 9 which is typical for finished water-based paints, VAM residuals within

CAS No.: 108-05-4 36R059_0505_env Draft of 04.05.2005 the formulated paints are rapidly hydrolysed at a rate constant of k Hydro = 1.6 l mol -1 s -1 (corresponding to a half-life of less than 4 days ). Therefore, residual VAM levels in waterbased paints will be negligibly low once the product enters the market and is used. In contrast, hydrolysis is distinctively slower in acidified dispersion paints, with a rate constant of k = 0.002 l mol -1 s -1 (kinetic data provided by industry in 2002).

3.1.2.1.5 Manufacture of adhesives
According to the European Adhesive s Manufactures Association FEICA ( F édération E uropéenne des I ndustries de C olles et A dhésifs) the vast majority of manufacturers of adhesives and tackifiers undertake only com pounding, thereby utilizing ready-made polymer formulations. Nonetheless, some sites were found out to conduct also VAM polymerisation for captive use. Unlike for other industry associ ations which submitted data in aggregated form, manufacturers of adhesives provided data on individual sites for the CEFIC questionnaire (sites 14-20, Table 3-9 )

3.1.2.1.6 Paper recycling and use of printing inks and paintings
From the high vapour pressure of the monomer, it is concluded that paper and cardboard will have lost all VAM residuals during service life time. When finally arriving at the recycling plant no residuals are anticipated to be included in the material any more. Hence, recycling of paper and cardboard is not deemed to be a re levant source of VAM for the hydrosphere. The same applies to printing inks, coatings and pa intings. No PEClocal for paper recycling was therefore derived.

3.1.2.2 Measured data in aqueous environment
Measured data of VAM in the aqueous compar tment are either not available from the open literature or relate to emission levels several decades ago. The available data may therefore be representative for the historical but not for the present situation.
In the CEFIC questionnaire, producers and user s of VAM were asked to provide monitoring data on VAM concentrations in the surface water bodies receiving their discharges. The companies either stated that no data is av ailable, or commented that VAM cannot be measured in surface water bodies as the concentr ation in the WWTP effluent is already below the analytical detection limit. The notified det ection limits at the outlets ranged from 5 - 100 μg/l.

3.1.3 Exposure Assessment for the Atmosphere

3.1.3.1 Estimation of local concentrations (Clocal air )
Within the CEFIC questionnaire some re sponding companies (majority of the VAM producers and several sites undertaking polymer isation) provided data on the VAM quantities released to air on an annual basis, or provi ded figures on measured aerial concentrations. Some other companies indicated data on request.

CAS No.: 108-05-4 37R059_0505_env Draft of 04.05.2005
3.1.3.1.1 Production of the Monomer
Almost all of the producers of VAM confirmed that routine venting of the plant is carried out and that the exhaust gas is flared. However, there is no evidence that this can be assumed for all plants. Moreover, diffuse releases from flanges, pumps etc. cannot be totally excluded.
Measured site-specific data was provided by a ll but one facility, and was used to override defaults in calculations. The producer comm unicating no data argued that no particular control data is available because of running a “closed circuit system” without emissions Due to the high volatility of vinyl acetate, the amount which is released via indirect emissions from STP cannot be ignored. In the tables below the amounts from production/processing and from STP are summed up under “total releases to air”.

Table 3-11: Estimation of local VAM concentrations in air and soil for VAM production sites

Site Clocal air (μg/m 3 ) DEP total_ann (mg/m 2

⋅ d 1 ) Comments Direct releases to air (t/year) Total releases to air (t/year)
4 0.3 8.20E-04 maximum value calculated from limit of detection < 0.37 7.51E-01

21 1.35E-01 1.95E-04 incineration and indirect release from STP 0 1.78E-01

22 3.87E-04 5.57E-07 incineration and indirect release from STP 0 4.18E-04

26 2.88E+02 2.38E-01 specific data 2.175E+02 2.175E+02
27 0 0 air emissions do not occur due to closed system, distillation of waste water and waste incineration (no STP) 0 0

Σ 2.18E+02 2.18E+02

CAS No.: 108-05-4 38R059_0505_env Draft of 04.05.2005
3.1.3.1.2 Processing of the Monomer

Release from point-sources: verified processing sites
The term “use” was interpreted by respondents to the CEFIC questionnaire in different ways: as synonym for any kind of activity downstream of production, i.e. polymerisation of VAM and/or handling and packing of the polymer solutions and resins (see steps 2 and 3 in section 2.1). Consequently, it could not be clarified which kind of activities each “user” actually performed.
Some of the respondents provided site-specifi c emission loads of VAM to the atmosphere. Releases were estimated for those sites that provided no data, with estimates ranging from as low as 0.4 x 10 -3 % up to 0.2 % of the processed vol ume. The facilities which manufacture high volumes of the polymer(s) all reported low emissions of approximately 5 x 10 -3 kg/t, due to incineration of off-gas. Small and medi um-scale facilities typically emit around 1 kg/t to air, although some employ some sort of purification equipment.

Table 3-12: Estimated local concentrations of VAM in air and deposition to soil

Site Clocal air ( μ g/m 3 ) DEP total_ann (mg/m 2

⋅ d 1 ) Comments Direct releases to air (t/year) Total releases to air (t/year)
1 3.28E-01 4.91E-04 site-specific data 4.30E-01 4.48E-01
2 2.00E+00 4.85E-03 site-specific data 2.63E+00 4.43E+00
3a 5.56E+00 8.09E-03 based on estimates 6.0E+00 6.07E+00
3b 9.27E+00 1.30E-02 based on estimates 1.0E+01 1.003E+01
3c 7.41E+00 1.10E-02 based on estimates 8.0E+00 8.003E+00
3d 3.71E+00 5.35E-03 based on estimates 4.00E+00 4.009E+00
5 2.93E-01 8.23E-04 site-specific data 3.67E-01 7.51E-01
6 8.45E+00 1.20E-02 site-specific data 1.11E+01 1.11E+01
7 5.4 7.8E-03 based on estimates 7.11E+00 7.113E+00
8 2.40E+01 3.40E-02 site-specific data 3.10E+01 3.13E+01
9 1.10E+01 1.50E-02 site-specific data 1.40E+01 1.40E+01
10 1.10E+01 1.50E-02 site-specific data 1.40E+01 1.40E+01
11 1.58E-03 2.27E-06 site-specific data 0 2.08E-03
12 5.71E+00 9.14E-03 site-specific data 7.50E+00 8.34E+00
13 2.99E-01 4.31E-04 calculation based on default of 1 kg/t 2.80E-01 2.80E-01

14 2.14E+00 5.58E-03 calculation based on default of 1 kg/t 2.00E+00 3.62E+00

15 1.60E+00 2.32E-03 site-specific data 1.50E+00 1.51E+00

CAS No.: 108-05-4 39R059_0505_env Draft of 04.05.2005

Site Clocal air ( μ g/m 3 ) DEP total_ann (mg/m 2

⋅ d 1 ) Comments Direct releases to air (t/year) Total releases to air (t/year)
16 9.7E+01 1.40E-01 site-specific data 7.00E-02 7.00E-02
17 3.71E-01 5.43E-04 site-specific data 4.00E-01 4.07E-01
18 7.41E-03 1.10E-02 site-specific data 8.00E+00 8.01E+00
19 6.49E-03 9.72E-03 site-specific data 7.00E+00 7.29E+00
20 9.27E-04 1.49E-06 site-specific data 1.00E-03 1.12E-03
23 8.01E-06 1.15E-08 site-specific data 1.05E-05 1.10E-05
24 1.90E+01 2.80E-02 site-specific data 2.49E+01 2.52E+01
25 3.24E+00 4.88E-03 site-specific data 3.50E+00 3.66E+00
28 7.41E+00 1.10E-02 site-specific data 8.00E+00 8.19E+00
29 2.22E-01 3.34E-04 site-specific data 2.00E-01 2.09E-01
30 1.48E-03 2.13E-06 site-specific data 0 1.60E-03
Σ 1.72E+02 1.78E+02

Release from point-sources: non-verified generic site

Based on a difference of 325,000 t/a between nominal production volume (800,000 t/a) and verified processing capacities (total of 475,000 t/a), a generic scenario was calculated for the local main source (fraction of main source = 0.15, cf. section 3.1.1.1.2 ).
A Clocal air of 45 μ g/m 3 , a DEP total_ann of 5.5E-02 mg/m 2

⋅ d 1 , a direct release of 48.75 t/a and a total release of 3.33 E+02 t/a to air are derived.

Release from diffuse sources

For a conservative estimate of the diffusive re leases from end-use products during service lifetime, a VAM total market supply of a bout 1,000,000 t/a and an average VAM content of 3,000 ppm in (co)polymers is assumed, leading to an estimated total release of 3,000 t/a, with a fractional release of 2,700 t/a (90 %) directed to the atmosphere (cf. section 3.1.1.1.3 ).

3.1.3.1.3 Manufacture of synthetic fibres
As communicated by CIRFS (2002), approximately 1 per mill (1 kg/t) of VAM is released to air. For fibre strands production (sites 3a-3d, Table 3-12 ), local concentrations in air and corresponding deposition rates are therefore based on a fraction of emission of 0.001 (0.1 %).

3.1.3.1.4 Manufacture of coatings and printing inks

CAS No.: 108-05-4 40R059_0505_env Draft of 04.05.2005 According to aggregated data provided by indus try association CEPE (Conseil Européen des Industries des Peintures, Encres d’Imprimerie et Couleurs d’Art), the air emissions of facilities manufacturing paints and printing inks ra nge from zero to > 7 t/a, with a mean of 1.1 t/a (based on 53 companies responding to a CEPE questionnaire in 2000).
The maximum reported value of 7.11 t/a was used to calculate local air concentrations (Clocal air ) and deposition rates (DEPtotal) for a prin ting ink / coating manufacturing site as a worst case scenario, following the provisions of the TGD (chapter 2.3.8.2). The results are provided in Table 3-12 (site 7).
Annual release to air by this industry sector is approximately 0.1 % of the reported annual use volume of 43,524 t/a. An estimated release of 43.5 t/a by all facilities manufacturing paints and printing inks is used in the regional assessment.

3.1.3.1.5 Manufacturing of adhesives
The calculated local concentrations of VAM in air and soil adjacent to adhesive manufacturing sites are included in Table 3-12 (sites 14-20).

3.1.3.2 Measured data in the atmosphere
Only very few measured vinyl acetate concentr ations in ambient air are available. Vinyl acetate was detected in the atmosphere of an industrial area in Texas (USA) in 1974 in concentrations up to 2 mg m -3

. In the ambient air of a landfill in New Jersey (USA), concentrations of 0.5 μg m -3 were measured in 1976. In a more recent study of 1990/91, cited in the SIDS Dossier, vinyl acetate was not detect ed in ambient air in Texas (representing the background concentration) at a detection limit of 2 ppb.
A monitoring campaign on non-methane volatile organic compounds (VOCs) was carried out in Italy, Spain and Germany, encompassing ur ban areas, suburban areas, forest-rural and remote areas. VAM was not detected in all samp les but occurred in “traces” in 6 % of the samples from remote areas, with “traces” m eaning “less than 0.5 % w/w of a total VOC concentration of 20-200 μ g/m 3 ” (Ciccioli et al., 1994). The results were interpreted by the authors in a way that biogenic sources contribut e substantial parts to the overall emissions of VOCs. In addition, VAM was formed under cond itions simulating incineration of pine wood and wheat straw. Forest fires and agricultural pr actises were therefore deemed to be a further anthropogenic source of VAM, particularly in Mediterranean countries (Ciccioli et al., 2001).

3.1.4 Exposure assessment for the terrestrial compartment
VAM may enter the terrestrial compartment by aerial deposition or by spreading of contaminated sewage sludge on soils. Based on the water solubility and octanol-water partition coefficient of VAM, it is anticipated that VAM is relatively mobile in soil. This is backed by QSAR calculations on the K oc , suggesting only little affinity to organic material.
Information provided by industry indicates that only small amounts of industrial sludge from VAM production and processing facilities is spread on soils. The majority of companies indicated that contaminated sludge is either incinerated or landfilled.

CAS No.: 108-05-4 41R059_0505_env Draft of 04.05.2005 Sludge from production sites is either incinera ted (2 sites), landfilled (1 site) or does not emerge at all since no WWTP is involved (2 sites). The same applies also for major polymerisation facilities. Several facilities indicat ed pre-treatment (e.g. electroflotation) of waste water on-site. Such treatment upstream of discharge to municipal sewer systems is to reduce TOC contents. The cakes from filter presse s are usually incinerated or transported to a landfill. However, no data was provided for a few small-size facilities.

Estimates on the fate of VAM in waste water tr eatment plants revealed that only 0.2 % of the VAM load entering the WWTP will remain with in the sludge. Further reduction in sludge concentrations is anticipated from subsequent digestion. From these considerations it is concluded that the main source of release of VAM to soil will be deposition from the atmospheric compartment after local releases to air from point sources. Small quantities of VAM entering the soil will be swiftly degraded (section 3.1.1.2.3).
As a worst case approach, soil concentrations were estimated for the two sites having the highest deposition rates of DEPtotal ann = 238 μg m -2 d -1 (site 26) and DEPtotal ann = 140 μg m -2 d -1 (16) according to the provisions of the TGD. Both facilities do not operate a STP so that sludge application is not included in the estimate. Soil concentrations were also calculated for several sites that had relatively high deposition ra tes and reported that sludge is being used on agricultural soils ( Table 3-13 ).

Table 3-13: Local concentrations of VAM in soil and in soil porewater

Clocal for DEP total_an

n (mg/m 2

⋅ d 1 ) C sludge (mg/kg) soil (mg/kg) agric. soil (mg/kg) grassland (mg/kg) soil porewater (mg/l) agric. soil porewater (mg/l) grassland porewater (mg/l)
26 2.38E-01 No STP 8.77E-03 8.77E-03 1.00E-02 1.60E-02 1.60E-02 1.90E-02
16 1.40E-01 No STP 5.16E-03 5.16E-03 6.03E-03 9.42E-03 9.42E-03 1.10E-02
3a 8.09E-03 0.56 6.13E-04 3.56E-04 3.63E-04 1.12E-03 6.50E-04 6.62E-04
3b 1.30E-02 0.28 6.36E-04 5.08E-04 5.67E-04 1.17E-03 9.27E-04 1.04E-03
3c 1.10E-02 0.02 4.18E-04 4.08E-04 4.74E-04 7.63E-04 7.44E-04 8.66E-04
3d 5.35E-03 0.07 2.40E-04 2.05E-04 2.34E-04 4.38E-04 3.77E-04 4.28E-04
6 1.20E-02 1.71 1.40E-03 6.17E-04 5.58E-04 2.55E-03 1.13E-03 1.02E-03

Furthermore, a generic scenario was calculated for the local main source (fraction of main source = 0.15, cf. section 3.1.1.1.2 ), based on a difference of 325,000 t/a between nominal production volume (800,000 t/a) and verified pr ocessing capacities (total of 475,000 t/a). From a DEP total_ann of 5.5E-02 mg/m 2

⋅ d 1 and a C sludge of 20.9 mg/kg, a Clocal soil of 0.014 mg/kg is calculated.

CAS No.: 108-05-4 42R059_0505_env Draft of 04.05.2005
3.1.5 Non compartment specific exposure relevant to the food chain
As the physical-chemical properties of VAM do not indicate any relevant bio-accumulation potential, the potential for secondary poisoning is considered to be low.

3.1.6 Regional concentrations
For the estimation of the regional background concentrations, the following releases from diffuse as well as point sources are taken into account.

Point source releases to surface water For the production and processing sites included in the CEFIC survey (cf. Table 3-1 and Table 3-2 ), annual releases of vinyl acetate to waste water were calculated, either based on default estimations or site-specific data provided. The identified production and processing sites have a combined annual load of 40 tonnes VAM, which is expected to end up in waste waters.

Not included in this estimated total release are the sites located at the sea (3b, 22, 27). The marine sites were exempted as they are not assumed to contribute to the PECregional for surface (fresh) water, that is used for risk characterisation of inland sites in section 3.3.1 . A marine risk assessment is included in Section 3.3.5.2

. Accounting for the difference between nomin al production volume (800,000 t/a) and verified processing capacities (total of 475,000 t/a), a generic scenario was calculated for the remaining processing volume of 325,000 t/a. A rel ease fraction of 0.02 % for waste water as communicated by industry was assumed to calculate a total release of 65 tonnes/year.

Point source releases to air For the production and processing sites included in the CEFIC survey (cf. Table 3-1 and Table 3-2 ), annual releases of vinyl acetate to at mosphere were calculated, either based on default estimations or site-specific data provided. The identified production and processing sites have a combined annual release of 389 tonne s VAM, which is expected to be released to the atmosphere. SimpleBox calculations of the PECregional for air take these direct releases as well as indirect releases of VAM from STPs into account.
Similar to surface water, a generic scenario was calculated. Applying a release fraction of 0.1 % to air as communicated by industry to the remaining processing volume of 325,000 t/a, results in a total release of 325 t/a.

Point source releases to soil No point sources were identified for the soil compartment.

Diffuse releases Residual monomers of vinyl acetate are diffusive ly released from products containing vinyl acetate polymers to the environment. Due to the high vapour pressure of the substance, it is

CAS No.: 108-05-4 43R059_0505_env Draft of 04.05.2005 assumed that around 90 % of the residual vinyl acetate contained in polymeric products enter the atmosphere, whilst 10 % are released into water during processing and formulation of the polymeric products.
Based on a residual VAM content of 3,000 ppm and a processing volume of roughly 1,000,000 tonnes, an annual release of 3,000 t/a can be estimated. It is assumed that 2,700 t/a (90 %) of the total annual release enter the atmo sphere, whilst 300 t/a (10 %) are released into waste water. Contrary to TGD specifications it is assumed that 100 % of the waste water is treated in WWTP because all waste water is produced by industrial facilities.
The following table summarizes the estimated emi ssions of vinyl acetate from different point and diffuse sources to water and atmosphere:

Emission to waste water (tonnes/year) Direct release to air (tonnes/year) Release from point-sources: verified processing sites 40.31 389.52
Release from point-sources: non-verified (based on 325,000 t/a) 65.00 325.00

Diffuse release from end-use products containing VAM 300.00 2,700.00

Total 405.31 3,414.52 Regional (10 %) 40.53 341.45 Continental (90 %) 364.78 3,073.06

Continental and regional background concentrations of vinyl acetate were calculated. A share of 90 % of the total releases was allotted to th e continental scale, while 10 % was allocated to the regional sector. The software tool Simp leBox 2.0a was used to predict the following continental and regional environmental concentrations (see Appendix 4):

Table 3-14: Regional and continental concentrations (PECs) according to SimpleBox 2.0a

Continental PECs Regional PECs
PECcont surfacewater 9.26E-07 mg l -1 PECreg surfacewater 8.35E-06 mg l -1

PECcont air 1.99E-06 mg m -3 PECreg air 1.03E-05 mg m -3

PECcont agr.soil 1.12E-07 mg kg wwt -1 PECreg agr.soil 9.18E-07 mg kg wwt -1

PECcont agr.soil,porew 2.06E-07 mg l -1 PECreg agr.soil,porew 1.68E-06 mg l -1

PECcont nat.soil 4.94E-08 mg kg wwt -1 PECreg nat.soil 2.56E-07 mg kg wwt -1

CAS No.: 108-05-4 44R059_0505_env Draft of 04.05.2005

3.2 EFFECTS ASSESSMENT: HAZARD IDENTIFICATION AND DOSE (CONCENTRATION) - RESPONSE (EFFECT) ASSESSMENT

3.2.1 Effects assessment for the aquatic compartment (including sediment)

3.2.1.1 Test results

3.2.1.1.1 Criteria for validation
Despite being a HPVC with a market supply of more than 1 million tonnes per year, only a comparatively small data set is available on th e ecotoxic effects of VAM. Toxicity studies can only be classified as valid if suitable precau tions have been taken to prevent decreasing exposure concentrations of the test substance due to volatilisation during the test (e.g. flowthrough or sealed vessels). Furthermore, exposur e concentrations should be measured in the course of the study. Test results which we re obtained under static conditions without analytical determination of test substance con centrations can only give a rough estimate of the ecotoxic effects, since the possible decrease in test concentrations due to volatilisation is not considered. In these cases it has to be assumed that the effective concentrations are lower as relevant parts of the test substance might have evaporated during the course of the test.
The most relevant test results for aquatic vert ebrates, invertebrates and algae are summarized in Table 3-15 and are described in more detail below.

CAS No.: 108-05-4 45R059_0505_envDraft of 04.05.2005Table 3-15:Summary of the most relevant results of toxicity testswith aquatic vertebrates, invertebrates and plants (algae)SpeciesDurationTest design / remarksEndpointConcentration(mg/l)ReferenceValidityVertebratesLepomismacrochirus96 hstatic (open system)endpoint mortality96 h-LC50adult:18 (n)Pickering &Henderson(1966)not validPimephalespromelas96 hstatic (open system)endpoint mortality96 h-LC50adult:19.7 (n)1 d old juveniles:14-15 (n)2 d old juveniles:15 (n)Pickering &Henderson(1966)not validPimephalespromelas34 dOECD 210 (Fish Early Life Stage)flow-through, analytical data34 d-NOEC34 d-LOEC0.55 (m)0.93 (m)ASG/CEFIC(2003b)validInvertebratesDaphniamagna48 hOECD 202, semi-static,sealed test vessels, analytical data,endpoint immobilisation24 h EC5048 h-EC5024.0 (m)12.6 (m)ASG/CEFIC(2003a)validDaphniamagna24 hstatic (open system)endpoint immobilisation24 h-LC5052 (n)Bringmann& Kühn(1982)not validArtemiasalina24 hstatic (open system)endpoint mortality24 h-LC5045 (n)Price et al.(1974)not validCAS No.: 108-05-446R059_0505_envDraft of 04.05.2005SpeciesDurationTest design / remarksEndpointConcentration(mg/l)ReferenceValidityOphryotrocha diadema(sedimentdwelling,marine)48 hdetermined one week after exposure,endpoint mortality48 h-LC5033 (n)Parker(1983)notvalidPlants (algae)Pseudokirchneriellasubcapitata(Selenastrumcapricornutum)96 hOECD 201, static, sealed test vessels withzero headspace, analytical data72 h-ERC5072 h-NOEC12.7 (m)5.96 (m)ASG/CEFIC(2003c)validScenedesmusquadricauda8 dcell multiplication inhibition test8 d-EC3370 (n)Bringmann& Kühn(1977a)notvalidMicrocystisaeruginosa8 dcell multiplication inhibition test8 d-EC335 (n)Bringmann& Kühn(1976,1978a,1978b)notvalid(n) nominal concentration (m) measured concentrationCAS No.: 108-05-447R059_0505_env Draft of 04.05.2005

CAS No.: 108-05-4 48 3.2.1.1.2 Fish

Acute toxicity Pickering and Henderson (1966) examined the e ffects of short term exposure of VAM in different species of fish. Tests were perfor med according to the methods recommended by the American Public Health Association (Standard Methods for the Examination of Water and Waste Water, 11th Ed., 1960). Fish were expos ed in open, static systems for 96 hours. Different concentrations of test solution we re prepared in a logarithmic series ranging nominally from 10 to 100 mg/l (temperature 25 °C, dissolved oxygen 7.8 mg/l, pH 7.5 - 8.2, water hardness as EDTA 20 - 172 mg/l, no aera tion throughout the test period). The test results obtained for bluegill ( Lepomis macrochirus ) and fathead minnow ( Pimephales promelas ) are summarized in Table 3-15 . As no chemical measurements were available the derived effect concentrations were related to nominal concentrations. The test results are therefore only of limited use for the effects assessment of VAM.

Long-term toxicity The chronic toxicity of VAM to the early life-stages of fathead minnow ( Pimephales promelas ) was examined under flow-through conditi ons by ASG/CEFIC (2003b) according to OECD-Guideline 210. One hundred embryos (< 30- hours post fertilization, 4 replicates of 25 embryos) per dose level and control were exposed to nominal concentrations of 0.389, 0.648, 1.08, 1.80, 3.00 and 5.00 mg vinyl acetate per litre. All test aquaria were sampled weekly throughout the duration of the study (days 0, 7, 14, 21, 28 and 34) and the collected samples were analysed for vinyl acetate using GC/EI-MS. The measured test solution concentrations were variable and did not remain within +/- 20 % of the mean measured concentrations over the course of the study. Study average percent of target values for vinyl acetate ranged from 41.8 to 60.8 % and resulted in mean measur ed exposure concentrations of 0.163, 0.353, 0.551, 0.930, 1.71 and 3.04 mg/l.
The test system was maintained for 31 days post hatch of the control embryos (34 days total). Based on mean measured concentrations, the no-observed-effect concentration (NOEC) and lowest observed-effect concentration (LOEC) were statistically determined for the following endpoints:

 percent of embryos that hatched (embryo survival)

 time to hatch (day-to-mean hatch)

 percent of normal larvae (larvae exhibiting no lethal or sublethal effects) at test termination

 percent larvae survival

 percent overall survival and growth (length and weight)
If the raw data (or alternatively the transforme d variables after logarithmic inverse or square root transformation) were found to be both normal (Shapiro-Wilk’s test) and homogeneous (Bartlett’s test), a parametric analysis was c onducted with a Dunnett’s test. Data that was not normally and/or homogeneous were analysed pa rametrically with a Steels’ Many-one rank test or Kruskal-Wallis test.R059_0505_env Draft of 04.05.2005

CAS No.: 108-05-4 49 The test results can be summarised as follows:

 No statistically significant ( α = 0.05) effects were observed for the percent of embryos hatched and the time to hatch endpoints up through the highest exposure level of 3.04 mg/l tested for these endpoints.

 No statistically significant ( α = 0.05) effects were observed for the percent normal larvae at test termination, the percent larv ae survival, and the percent overall survival up to the exposure concentration of 0.551 mg/l. Statistically significant effects for these endpoints were observed at exposure levels of 0.93 mg/l and above. These effects showed a clear concen tration-dependency: While 93.9 ± 13.8 % of the larvae survived and showed normal development at a test concentration of 0.551 mg/l, this fraction was reduced to 78.0 ± 5.2 % at the next higher exposure level of 0.93 mg/l, to 32.5 ± 11.0 % at 1.71 mg/l, and to zero at the highest exposure level of 3.04 mg/l.

 No statistically significant (alpha = 0.05) diffe rences in growth (lengths, weights) of surviving organisms at study terminati on were observed up through the highest exposure level tested for this endpoint (1.71 mg/l).
Therefore, NOEC and LOEC were determined with 0.551 and 0.930 mg/l.

Table 3-16: Chronic toxicity of VAM for early life stages of Pimephales promelas

Parameter NOEC (m) (mg/l) LOEC (m) (mg/l) Weight (mg) 1.71 > 1.71 Length (mm) 1.71 > 1.71 Percent embryos hatched 3.04 > 3.04
Time to hatch 3.04 > 3.04
Percent normal larvae 0.551 0.930
Percent larvae survival 0.551 0.930
Percent overall survival 0.551 0.930
(m) measured concentration

3.2.1.1.3 Aquatic invertebrates

Acute toxicity
An acute 48-hour Daphnia magna toxicity test with VAM was conducted under semi-static conditions according to the OECD-Guidelin e 202 by ASG/CEFIC (2003a). The study was performed with 20 daphnia (ten individuals per re plicate with two replicates per dose level) exposed to nominal test concentrations of 4.28, 7.13, 11.9, 19.8, 33.0 and 55 mg vinyl acetate per litre. Due to the volatility of the test mate rial serum bottles were filled to capacity and sealed. In order to maintain the exposure c oncentrations and dissolved oxygen levels test solutions were renewed after 24 hours. The concen tration of vinyl acetate in the test solutions were confirmed in new and old test media via GC/EI-MS. The time-weighted mean (TWM)R059_0505_env Draft of 04.05.2005

CAS No.: 108-05-4 50 measured values ranged from 66.9 to 110 % of target concentration resulting in TWM measured concentrations for the study of 2.91, 4.77, 9.77, 14.9, 31.0 and 60.5 mg vinyl acetate / l. A 24 h-EC50 of 24.0 mg/l (95 % confidence limits 20.2-29.0 mg/l) and a 48 hEC50 of 12.6 mg/l (95 % confidence limits 11.2- 14.4 mg/l) were obtained from this study, indicating that toxicity is increasing with the duration of exposure.
Additional static tests are available using Daphnia magna (Bringmann and Kühn 1982), the brine shrimp Artemia salina (Price et al., 1974) and the marine polychaete Ophryotrocha diadema (Parker, 1983). As only nominal concentrations are reported, these studies are regarded as invalid and not suitable for e ffects assessment purposes, but are nevertheless described in more detail below for completeness.
In an acute immobilization study with Daphnia magna (Bringmann and Kühn 1982) a 24 hEC 50 of 52 mg/l related to nominal concen trations was derived. The corresponding LC 0 and LC 100 value was 17 mg/l and 128 mg/l. The test wa s performed in an open, static system (local tap water free from chlorine, saturate d with oxygen / content of at least 2 mg/l, temperature: 20 °C, pH at beginning of test: 7.8 - 8.2, water hardness: 16° dH.).
Price et al. (1974) examined the toxicity of vinyl acetate to the brine shrimp Artemia salina

. In a static test conducted with artificial sea water a 24 h-LC 50 of 45 mg/l based on nominal concentrations was found. During the study bottles were loosely capped and incubated at ambient temperature (24.5 °C). After incubati on the number of live and dead shrimp were noted by viewing the shrimp in the bottle aided by a colony counter.
Another static toxicity test in filtered sea wa ter (temperature: 21 °C) was carried out by Parker (1983) using the marine polychaete Ophryotrocha diadema as test organism. For the study a half-logarithmic series of concentrations was applied. After an 48 hours exposure period, surviving animals were transferred into pure s ea water, where they were allowed to recover for one week. Any animals which died during th is period were recorded along with the earlier mortalities in the test. A 48 h-LC 50 of about 33 mg/l (nominal concentration) was derived from this study for vinyl acetate.

Long-term toxicity Tests on long-term effects of vinyl acetate on aquatic invertebrates are not available.

3.2.1.1.4 Aquatic algae
The only reliable test result for aquatic algae wa s obtained from a growth inhibition test with the freshwater green alga Pseudokirchneriella subcapitata (ASG/CEFIC, 2003c). Due to the volatility of vinyl acetate several deviations of th e standard algal bioassay were made in order to maximize the retention time of the substance in the test medium over the exposure period:

 The study was performed under zero headspace conditions in sealed test vessels.

 In order to avoid CO 2 -limitation the content of sodium carbonate in the growth medium was increased by a factor of five.

 Test vessels were not shaken during the incubation period.R059_0505_env Draft of 04.05.2005

CAS No.: 108-05-4 51  For the daily cell density determinations test vessels were vigorously shaken prior to unsealing to suspend as much biomass as possible.

 After sampling, additional test medium from a surrogate test vessel was added in order to maintain zero headspace conditions.

The algae were exposed to six nominal test concentrations of 1.56, 3.13, 6.25, 12.5, 25.0, 50 and 100 mg vinyl acetate / l over a 96-hour period. Since the concentration of vinyl acetate declined over time (after 72 hours between 75 and 30 % of the target concentrations were still present in the test solutions), time weighted means (TWM) were calculated leading to 72-hour TWMs of 0.331, 0.733, 1.58, 5.96, 6.57, 14.9 and 34.7 mg/l. Based on these TWMs the following test results were obtained:

Table 3-17: Toxicity of vinyl acetate in algae (Pseudokirchneriella subcapitata)

Parameter Endpoint Concentration (mg/l) (m)
Growth rate 72 h-ERC50 12.70 (95 %-CI: 9.50-17.1)
NOEC 5.96
Biomass 72 h-EBC50 7.48 (95 %-CI: 1.60-34.9)
NOEC 1.58
(m) measured concentration
For comparison purposes a second test using st andard algal bioassay techniques was conducted by the same authors. Since the concentration of vinyl acetate declined very rapidly (after 24 hours only 0.4 - 0.8 % of the target concen tration was found in the highest tested concentrations of 50 - 200 mg/l) and the vinyl acetate concentrations tested were not set high enough to determine a concentration-response curv e, the test results of the zero-headspace bioassay are regarded as more reliable.
The green algae Scenedesmus quadricauda was investigated in a cell multiplication study by Bringmann and Kühn (1977a). Under this met hod, the onset of cell multiplication inhibition by different substances was determined. From this study an 8d-TGK value of 370 mg/l for vinyl acetate was obtained. Another cell multiplica tion inhibition test with the blue-green algae Microcystis aeruginosa as test organism found an 8d- TGK value of 35 mg/l (Bringmann and Kühn, 1976, 1978a, 1978b).
In both tests, the substances were dissolved in distilled water (temperature 27 °C, pH 7 at beginning of test). As the effect concentrations were related to nominal concentrations and presumably the algae were not in the exponentia l growth phase during the whole test duration, both studies are classified as not valid.R059_0505_env Draft of 04.05.2005

CAS No.: 108-05-4 52 3.2.1.1.5 Microorganisms
The toxicity of vinyl acetate to different microorganisms was examined by Bringmann and coworkers using cell multiplication inhibition tests. The following test results based on nominal concentrations were obtained:

Table 3-18 : Toxicity of VAM to microorganisms

Species Effect Endpoint Concentration (mg/l) pH / temp. Reference

Pseudomonas putida inhibtion of cell multiplication 16 h-EC 3 6 (n) 7.0 / 25 °C Bringmann & Kühn (1976, 1977a)
Chilomonas paramaecium (Protozoa) inhibtion of cell multiplication 48 h-EC 5 9.5 (n) 6.9 / 20 °C Bringmann et al. (1980)

3.2.1.2 Calculation of Predicted No Effect Concentration (PNEC)

3.2.1.2.1 Surface water (PNEC aqua )
Due to the volatility of vinyl acetate, only eff ect values based on analytically measured concentrations are suitable for derivation of the PNEC. Reliable acute test results are available for aquatic invertebrates and algae. For aquatic vertebrates a valid long-term test result is reported. As long-term NOECs from species representing two trophic levels are available (algae and fish), an assessment factor of 50 is proposed. Applying this factor to the long-term NOEC as determined in an ELS test using Pimephales promelas , the PNEC for aquatic ecosystems is calculated as follows:

PNEC aqua = 0.55 mg/l 

### / 50 = 0.011 mg/l

3.2.1.2.2 Sewage treatment plants (PNEC STP )
According to the procedure described in the T GD for assessing the toxicity of a substance to microorganisms in order to identify adverse e ffects in WWTPs, an assessment factor in the range of 10 to 100 is applied for tests on microorganisms with different sensitivities and different endpoints.
For vinyl acetate, an EC 3 -value of 6 mg/l is reported for Pseudomonas putida , which can be considered as a NOEC-value for microorganisms

. For the determination of a PNEC STP , an assessment factor of 10 is proposed for this kind of test result, which leads to:

PNEC STP = 6 mg l 

### / 10 = 0.6 mg/lR059_0505_env Draft of 04.05.2005
3.2.1.2.3 Sediment (PNEC sed )
Information on toxic effects of vinyl acetate on benthic organisms is not available. A provisional PNEC sed can be calculated using the equilibrium partitioning method of the TGD:

PNEC sed = K susp_water RHO susp x PNEC = water 1.51 m 3 m 3

. 1300 kgwwt m 3 x 0 .011 mg l 1

. x 1000 = 1.27 E-02 mg/kg

As measured data on concentrations of vinyl acet ate in sediment is not available either, the PEC has to be derived with the same method. If both PEC and PNEC are calculated using the equilibrium partitioning method, the same risk ra tios as for surface water are obtained. It is therefore referred to the risk characterisation for surfaces waters in section 3.3.1

. The above equation only considers uptake via th e water phase, but uptake may also occur via other exposure pathways like ingestion of sedi ment. However, these other exposure pathways are considered negligible due to the low ad sorptive properties of vinyl acetate and the low affinity to organic material. In addition, VAM is degraded hydrolytically and biologically in sediments. A significant transfer of VAM into th e sediment-phase is therefore not expected.
As the equilibrium partitioning method will yield th e same risk ratios as for surface water and as a significant transfer of VAM into the sedi ment-phase is not expected, a quantitative risk assessment for sediments is not considered necessary.

3.2.2 Effects assessment for the terrestrial compartment

3.2.2.1 Terrestrial effect data

No terrestrial effect data based on standard soil test organisms (e.g. earthworms, collembolan, microorganisms) is available.
Burditt et al. (1963) investigated the potential of using vinyl acetate as a fumigant to eggs and larvae of fruit flies Ceratitis capitata and Dacus dorsalis (both Diptera). Effect values were based on 2 h exposure followed by 48 h of observation.
A further fumigation test with terrestrial orga nisms was carried out at 25 °C for 3 h by Ittah and Zisman (1992) using Theba pisana (Mollusca: Helicidae) as test organism. In this study the fumigation was also followed by 48 h of obser vation. The derived effect values from both studies are summarized in the table below.

CAS No.: 108-05-4 53R059_0505_env Draft of 04.05.2005
Table 3-19 : Fumigation tests with fruit flies ( Ceratitis capitata and Dacus dorsalis ) and mollusc ( Theba pisana ) Species Age Effect Duration of fumigation Effect Concentr. (g/m3) Reference

Ceratitis capitata 24 h old eggs mortalit y 2 h 2 h-LC 50 2 h-LC 95 53 90 Burditt et al. (1963)
Ceratitis capitata mature larvae mortalit y 2 h 2 h-LC 50 2 h-LC 95 43 60 Burditt et al. (1963)

Dacus dorsalis 24 h old eggs mortalit y 2 h 2 h-LC 50 > 96 Burditt et al. (1963)

Dacus dorsalis mature larvae mortalit y 2 h 2 h-LC 50 2 h-LC 95 46 70 Burditt et al. (1963)
Theba pisana differing ages mortalit y 3 h 3 h-LC 31 2.3 Ittah & Zisman (1992)

3.2.2.2 Calculation of PNEC soil The available test results on terrestrial organi sms (i.e. diptera and mollusca) are originated from fumigation studies. The PNEC soil cannot be deduced from these data. According to the TGD, the risk assessment is performed on th e basis of the equilibrium partition method (EPM) if no standard test data with soil dwelling organisms is available (equation 72):

PNEC soil = K soil_water
RHO soil x PNEC = water 0.931 m 3 m 3

. 1700 kgwwt m 3

. x 0.011 mg l 1

. x 1000 = 6.02E-03 mg/kg

3.2.3 Effects assessment for the atmosphere

3.2.3.1 Biotic effects
Data on toxicity of airborne VAM are very scarce.

For the mollusc Theba pisana , a 3 h-LC 31 of 2.3 g/m 3 is reported. This effect concentration is in the same order of magnitude as the results from the acute inhalation studies with mammals.
No experimental data on toxicity of VAM to terrestrial plants is available. Therefore no PNEC air can be calculated for terrestrial vegetation.

CAS No.: 108-05-4 54R059_0505_env Draft of 04.05.2005

CAS No.: 108-05-4 55 3.2.3.2 Abiotic effects

3.2.3.2.1 Global warming
Vinyl acetate absorbs solar irradiation wavele ngths in the infrared region of 1,000 - 1,200 nm. Compared to the global warming effects cau sed by other substances (e.g. carbon dioxide) emitted from anthropogenic sources, the contribu tion of vinyl acetate to the overall man-made global warming potential (GWP) plays only an insignificant role, taking into account the released amounts and the short half-life of VAM in air.

3.2.3.2.2 Troposheric ozone
Ground-level ozone is formed by the reaction of VOCs and NO x in the presence of heat and sunlight. To this end vinyl acetate enhances formation of ground level ozone. The reactions that form ozone do not take place instantaneous ly, but can take hours or days. Nevertheless it cannot be excluded that for specific meteorologic conditions and intensive solar irradiation the contribution to ozone peaks may be substantial in the immediate vicinity of emission sources. On the regional scale, however, there ar e sources of (biogenic) volatile substances being of much more significance. Notwithstanding any feasible measure should be undertaken to abate releases of vinyl acetate to air in or der to curb formation of ground level ozone. As compared to other volatile organics ozone-f orming ability of vinyl acetate was found to be moderate (Joshi et al., 1982).

3.2.3.2.3 Stratospheric ozone (ODP)
The atmospheric lifetime of VAM is too short to allow for transport of relevant shares up to the stratospheric layer. In addition, the subs tance does no include any halogen atoms which could be split off and thereby form any free radicals that are capable of decomposing stratospheric ozone.

3.2.3.2.4 Acidification
Vinyl acetate is easily decomposed in the atmo sphere, forming acetaldehyde and subsequently acetic acid. Following wet and dry deposition th e substance may enter surface water bodies. However, acetic acid is not a strong acid (pKa = 4.76). Compared to atmospheric loads of other substances that form stronger acids such as NO x and SO 2 , the acidification potential of vinyl acetate is relatively low and the overall impact on surface water bodies negligible.

3.2.4 Non compartment specific effects relevant to the food chain
As vinyl acetate does not present indications of a bioaccumulation potential, an effect assessment for secondary poisoning is not required.R059_0505_env Draft of 04.05.2005

CAS No.: 108-05-4 56 3.3 RISK CHARACTERISATION
As a follow up to conclusion (i), which was drawn in the first draft of the Environment Section of the Comprehensive Risk Assessment Report of vinyl acetate (August 2002), further acute and long-term toxicity tests with aquatic orga nisms were performed and more data on a number of production and processing site s could be obtained, leading to the following refined and revised risk characterisation.

3.3.1 Aquatic compartment (incl. sediment)

Sewage treatment plants
Based on a PNEC STP of 600 μg/l (cf. section 3.2.1.2.2 ) and PEC STP values derived for the different production, processing a nd manufacturing sites (= Clocal eff values, equation 38 of the TGD), the following PEC : PNEC ratios for waste water treatment plants were calculated.

Table 3-20 : Local risk characterisations for STPs

Site Exposure source PEC STP (μg/l) PEC STP : PNEC STP

1 processing 5.00E+01 0.08
2 processing 1.00E+01 0.02
3a processing 1.00E+02 0.17
3b processing 5.00E+01 0.08
3c processing 4.00E+00 0.01
3d processing 1.30E+01 0.02
4/5 production/processing 5.00E+01 0.08

6 processing 3.04E+01 0.05
7 processing 5.00E+00 0.01
8 processing 2.30+01 0.04
9 processing 9.81E+01 0.16
10 processing 3.10E-02 0.00
11 processing 5.70E+00 0.01
12 processing 2.57E+01 0.04
13 processing 0.00E+00 - 14 processing 7.69E+01 0.13
15 processing 1.04E+01 0.02
16 processing 0.00E+00 - 17 processing 1.16E-04 0.00
18 processing 1.27E+01 0.02R059_0505_env Draft of 04.05.2005

CAS No.: 108-05-4 57 Site Exposure source PEC STP (μg/l) PEC STP : PNEC STP

19 processing 9.61E+01 0.16
20 processing 1.91E-06 0.00
21 production 1.03E+01 0.02
22 production 4.00E-01 0.00
23 processing 0.00E+00 - 24 processing 1.21E+02 0.20
25 processing 2.67E-04 0.00
28 processing 5.33E+01 0.09
29 processing 8.11E-01 0.00
30 processing 7.70E-01 0.00

An evaluation of the inhibition of microbial activity in STPs seems reasonable only for those sites where vinyl acetate-containing waste water is released to biological treatment plants. The production sites which are not connected to a biological WWTP, as their waste water is treated within the process (site 26 and 27), were thus excluded from the risk characterisation. As VAM is typically produced in closed systems and dissolved vinyl acetate monomers are often recovered from waste water streams, i.e. by fractional distillation to increase reaction yields, residual levels in the waste water are generally low (cf. section 3.1.2.1.1 ). For the remaining production sites (4, 21 and 22) discharg ing to waste water treatment plant, no risk was therefore identified.
Based on a difference of 325,000 t/a between nominal production volume (800,000 t/a) and verified processing capacities (total of 475,000 t/a), a generic scenario was calculated for the local main source (fraction of main source = 0.15). A PEC STP of 325 μg/l was derived, resulting in a PEC : PNEC ratio of 0.54.
Conclusion (ii) There is at present no need for further information and/or testing and for risk reduction measures beyond those which are being applied already.
This conclusion applies to all production, processing and manufacturing sites.R059_0505_env Draft of 04.05.2005

CAS No.: 108-05-4 58 Surface water

A PNEC aqua of 11 μg/l for surface water has been determined (cf. section 3.2.1.2.1 ).
Using the PNEC aqua and a PECreg surfacewater of 8.35E-03 μg/l (cf. section 3.1.6 ), the risk ratio for the regional environment is calculated as follows:
PECreg surfacewater : PNEC aqua = 8.35E-03 μg/l : 11 μg/l = 7.59E-04

From the PNEC aqua and the estimated PEClocal water ( = Clocal water + PECreg surfacewater ) for the different production and processing sites, the risk ratios for the local environments are calculated as follows:

Table 3-21 : Local risk characterisations for surface water (freshwater)

Site Exposure source PEClocal water (μg/l) PEClocal water : PNEC aqua

1 processing 8.83E-03 0.00
2 processing 7.44E-02 0.01
3a processing 1.00E+01 0.91
3b processing see marine risk assessment
3c processing 4.08E-01 0.04
3d processing 1.31E+00 0.12
4/5 production/ processing 2.17E-01 0.02

6 processing 3.05E+00 0.28
7 processing 5.08E-01 0.05
8 processing 2.31E+00 0.21
9 processing 9.89E-01 0.09
10 processing 1.14E-02 0.00
11 processing 1.40E-01 0.01
12 processing 2.11E+00 0.19
13 processing 8.35E-03 0.00
14 processing 7.70E+00 0.70
15 processing 1.03E+01 0.94
16 processing 8.35E-03 0.00
17 processing 8.36E-03 0.00
18 processing 1.28E+00 0.12
19 processing 9.62E+00 0.87
20 processing 8.35E-03 0.00R059_0505_env Draft of 04.05.2005

CAS No.: 108-05-4 59 Site Exposure source PEClocal water (μg/l) PEClocal water : PNEC aqua

21 production 7.64E-02 0.01
22 production see marine risk assessment
23 processing 8.35E-03 0.00
24 processing 1.56E-02 0.00
25 processing 8.38E-03 0.00
26 production 8.35E-03 0.00
27 production see marine risk assessment
28 processing 1.34E+00 0.12
29 processing 1.04E-02 0.00
30 processing 1.01E-02 0.00

For the difference of 325,000 t/a between nominal production volume (800,000 t/a) and verified processing capacities (total of 475,000 t/a ), a generic scenario was calculated based on a fraction of main source of 0.15. A PEClocal water of 8.13 μg/l was derived, resulting in a PEC : PNEC ratio of 0.74. A risk to the local or regional aquatic co mpartment was not identified for production and processing of vinyl acetate. This conclusion applies to all sites and the generic scenario.

- Conclusion (ii) There is at present no need for further information and/or testing and for risk reduction measures beyond those which are being applied already.R059_0505_env Draft of 04.05.2005

CAS No.: 108-05-4 60 Sediment
Information on toxic effects of vinyl acetate on be nthic organisms is not available, neither are measured data on concentrations of vinyl acet ate in sediment. Both PEC and PNEC can be calculated using the equilibrium partitioning method, which will result in the same risk ratios as were obtained for surface water.
This approach only considers uptake of vinyl acetate via the water phase, but uptake may also occur via other exposure pathways like ingesti on of sediment. These other exposure pathways are considered negligible due to the low ad sorptive properties of vinyl acetate and the low affinity to organic material. In addition, VAM is degraded hydrolytically and biologically in sediments. A significant transfer of VAM into th e sediment-phase is therefore not expected.
On the basis of the available information, it is concluded that an unacceptable risk for sediments and sediment dwelling organisms is generally not to be expected from vinyl acetate.

Conclusion (ii) There is at present no need for further information and/or testing and for risk reduction measures beyond those which are being applied already.

3.3.2 Atmosphere
Due to the high volatility of VAM it is expected that – once released into the environment – the main compartment for environmental expos ure is air. This finding is supported by the results of environmental distribution models based on the physico-chemical data of VAM.
VAM beaks down rapidly in the atmosphere with a globally and seasonally averaged half-life of approximately 0.6 days (cf. section 3.1.1.2.1 .) Hence transport from points of release over long distances can be excluded.
Although no breakdown products have been identif ied it seems likely that even more polar fragments are generated through addition to th e olefinic bonds. Among the expected reaction products is formaldehyde (Atkinson, 1995). Besides photooxidation, wet deposition of VAM and its breakdown products is expected to be an important physical removal process from the atmosphere. Concurrently, cloud droplets furthe r contribute to hydrolytic degradation of VAM in moist air. Since acetaldehyde and its oxidation product acetic acid show some acidification potential, their wet deposition adds to acidification of weakly buffered surface waters. From the results of this risk assessm ent it is however concluded that the specific contribution of VAM degradation products will not be of any relevance as compared with other substances.
From its high vapour pressure and low K ow value it is concluded that either adsorption to airborne particles and aerosols is of relevan ce. In addition there is no indication that VAM significantly adds to adverse effects on other parameters of atmospheric quality like global warming or ozone depletion.
At air concentrations of approximately 2 g/m 3 significant biotic effects were observed. However, the data basis is far too scarce to derive a PNEC from this test result. As the highestR059_0505_env Draft of 04.05.2005

CAS No.: 108-05-4 61 calculated local concentration of approx. 0.3 μg/m 3 is several orders of magnitude lower, further tests on this endpoint seem not to be of high priority.
It is concluded that an unacceptable risk fo r the environment via the atmosphere is not expected from vinyl acetate.
Conclusion (ii) There is at present no need for further information and/or testing and for risk reduction measures beyond those which are being applied already.

3.3.3 Terrestrial compartment

No terrestrial effect data based on standard soil test organisms (e.g. earthworms, collembolan, microorganisms) is available. A PNEC soil = 6.02E-03 mg/kg was ther efore derived using the equilibrium partition method of the TGD.
It is expected that the main pathway of VAM immission into soil is aerial deposition after local releases to air from point sources, rath er than sludge application: Only 0.2 % of the VAM load entering a STP is expected to adso rb to sludge, and most companies producing or processing VAM reported either incineration or landfill of STP sludge.
As a worst case approach, soil concentrations were estimated for the two facilities with highest aerial deposition rates. Both facilities do not operate a STP so that sludge application is not included in the estimate (site 26 and 16). Furthermore, soil concentrations were calculated for several sites that had relatively high aerial deposition rates and reported sludge application on agricultural soils.

From the PNEC soil and the PEClocal soil (= Clocal soil + PECreg nat.soil ) for the selected production and processing sites, the risk ratios for the local environment are calculated as follows:

Table 3-29 Local risk characterisations for terrestrial soil

Site Exposure source PEClocal soil PEClocal soil : PNEC soil 26 production (no STP) 8.77E-03 1.46
16 processing (no STP) 5.16E-03 0.86
3a processing 6.13E-04 0.10
3b processing 6.36E-04 0.11
3c processing 4.18E-04 0.07
3d processing 2.40E-04 0.04
6 processing 1.40E-03 0.23

A potential risk was identified for production s ite number 26, based on a deposition rate that was derived from site specific data provided by the company operating the plant.
A potential risk was also identified for the generic scenario calculated for the local main source (fraction of main source = 0.15), base d on a difference of 325,000 t/a between nominal production volume (800,000 t/a) and verified pr ocessing capacities (total of 475,000 t/a). A PEClocal soil of 0.014 mg/kg was derived, resulting in a PEC : PNEC ratio of 2.33.R059_0505_env Draft of 04.05.2005

CAS No.: 108-05-4 62 Conclusion (i): There is need for further information and/or testing
A risk to the local terrestrial compartment wa s identified for the life cycle stages of vinyl acetate production and processing. This conclusion applies to one major production site (site number 26) and for the generic processing scenario calculated for the local main source. There is a need for further information and/or testing to adequately characterize the potential risks to the terrestrial compartment by refini ng the PNECsoil. It is recommended to perform an earthworm acute toxicity test (OECD 207) and a terrestrial plants growth test (OECD 208). The need for further testing should be reconsid ered in case that risk reduction measures are being applied at the site indicating a risk to the terrestrial compartment (site number 26). If no risk remains after risk reduction measures have been applied for the life cycle stage of vinyl acetate production, conclusion ii) should follow.

3.3.4 Non compartment specific effects relevant to the food chain
As there is no indication for vinyl acetate to be a potentially bioaccumulative substance, it was abstained from assessing effects for secondary poisoning.

3.3.5 Marine Assessment including PBT Assessment

3.3.5.1 PBT Assessment
The following table shows the PBT/vPvB criteri a as defined in the TGD and the respective values of vinyl acetate as derived in chapter 3 of this risk assessment.

Table 3-28 PBT/vPvB criteria according to TGD and data for vinyl acetate

PBT-criteria vPvB-criteria VAM
P half-life > 60 d in marine water or > 40 d in freshwater
or half-life > 180 d in marine sediment or > 120 d in freshwater sediment half-life > 60 d in marine water or freshwater
or half-life > 180 d in marine or freshwater sediment readily biodegradable in surface water, half-life: 15d (section 3.1.1.2.2 )

B BCF > 2,000 BCF > 5,000 BCF of 3.16 (section 3.1.1.3.5 )
T chronic NOEC < 0.01 mg/l or CMR or endocrine disrupting effects not applicable 34 d NOEC (fish): 0.551 mg/l (section 3.2.1.1.2 )

Vinyl acetate was found to be readily biodegradable in sewage treatment plants and is also considered as readily biodegradable in surface water. No standard tests on degradation ofR059_0505_env Draft of 04.05.2005

CAS No.: 108-05-4 63 vinyl acetate in soil or sediment are available, but different studies indicate that the substance is biotransformed and abiotically degraded in soil and sediment.
A BCF of 3.16 was derived from log Kow of 0.73. Measured BCF are not available.
A 34 d NOEC of 0.551 mg/l was found for fathead minnow ( Pimephales promelas ).
It can be concluded that vinyl acetate does not meet any of the PBT/vPvB criteria.

Conclusion (ii) There is at present no need for further information and/or testing and for risk reduction measures beyond those which are being applied already.

VAM does not meet the PBT/vPvB criteria.

3.3.5.2 Marine Assessment
There is no indication that VAM persists or accu mulates in the environment. However, it is known that two production sites (site 22 and 27) a nd one processing site (site 3b) discharge to the marine or estuarine environment. PEClocal for these sites are based on site-specific data in combination with default values from the TGD. Two facilities operate a WWTP (site 22 and 3b). The company operating the other pr oduction plant (site 27) reported that new technology had been implemented in the recently commissioned facility in order to contain and recover VAM in the process (i.e. closed syst em process, distillation of wastewater for reintroduction of material in the process, incine ration of remaining waste). Thus VAM in the waste water is either recycled or remaining material is incinerated. As a first approach, the marine regional bac kground concentration was derived from the fresh water regional background concentration by division by 10:

PEC regional_seawater = 8.35E-03 μg/l / 10 = 8.35E-04 μg/l

The PEC regional_seawater was added to the Clocal water to obtain the respective PEClocal water for the marine sites. The PNEC marine was derived by dividing the PNEC aqua by 10:

PNEC marine = PNEC aqua / 10 = 11 μg/l / 10 = 1.1 μg/l

Based on these values, the following PEC : PNEC ratios < 1 for all sites are derived.

Table 3.22 PEC : PNECseawater ratios for marine sites

Site Clocals seawater (μg/l) PEClocal seawater (μg/l) PEClocal seawater : PNEC marine 3b processing 5.00E-01 5.01E-01 0.46
22 production 4.00E-03 4.84E-03 0.00
27 production 0.00E+00 8.35E-04 0.00R059_0505_env Draft of 04.05.2005

CAS No.: 108-05-4 64 Conclusion (ii) There is at present no need for further information and/or testing and for risk reduction measures beyond those which are being applied already.
Conclusion (ii) applies to all identified marine sites.R059_0505_env Draft of 04.05.2005

CAS No.: 108-05-4 65 4 HUMAN HEALTH

4.1 HUMAN HEALTH (TOXICITY)

4.1.1 Exposure assessment

4.1.1.1 Indirect exposure via the environment
According to Appendix VII of chapter 2 of the TGD, the indirect exposure to humans via the environment, i.e. through food, drinking water and air is estimated.
As a worst case scenario, the maximum intake due to exposure in the vicinity of a vinyl acetate production facility is calculated (site 26). This is compared to an average intake due to exposure via the regional background concentration.

The resulting total daily dose is: DOSE tot_local = 36 μ g / kg bw d

DOSE tot_regional = 2.47 E-03 μg / kg bw d

The calculated total doses comprise the following routes:

Percent of total dose Route
local regional Drinking water 1.26 9.64
Fish 2.97E-05 0.44
Stem 0.36 0.33
Root 0.24 0.37
Meat 2.04E-04 2.41E-04
Milk 3.80E-03 4.50E-03
Air 98.13 89.22

The main route of indirect exposure of both scenarios is the intake via inhalation of air.R059_0505_env Draft of 04.05.2005

5 CONCLUSIONS / RESULTS

Overall results of the risk assessment:

(x) i) There is need for further information and/or testing
(x) ii) There is at present no need for furt her information and/or testing and for risk reduction measures beyond those which are being applied already
() iii) There is a need for limiting the risks; risk reduction measures which are already being applied shall be taken into account

Summary of conclusions:

Environment
As a follow up to conclusion (i), which was drawn in the first draft of the Environment Section of the Comprehensive Risk Assessment Report of Vinyl acetate (August 2002), further acute and long-term toxicity tests were performed for the aquatic compartment and more data on a number of production and processing sites were obt ained, leading to the following revised risk characterisation.

conclusion i):

Terrestrial compartment
A risk to the local terrestrial compartment wa s identified for the life cycle stages of vinyl acetate production and processing. This conclusion applies to one major production site (site number 26) due to aerial deposition of vinyl acetat e in the vicinity of the site and for the generic processing scenario calculated for the local main source.
There is a need for further information and/or testing to adequately characterize the potential risks to the terrestrial compartment by refining the PNEC soil . It is recommended to perform an earthworm acute toxicity test (OECD 207) and a terrestrial plants growth test (OECD 208). The need for further testing should be reconsid ered in case that risk reduction measures are being applied at the site indicating a risk to the terrestrial compartment (site number 26). If no risk remains after risk reduction measures have been applied for the life cycle stage of vinyl acetate production, conclusion ii) should follow.

CAS No.: 108-05-4 66R059_0505_env Draft of 04.05.2005 conclusion ii):

Aquatic compartment
A risk to the local or regional aquatic comp artment (surface water and sediments) was not identified for production and processing of vinyl acetate. This conclusion applies to all sites. Atmospheric compartment
Based on a qualitative risk characterisation, no unacceptable risk for the atmosphere is expected from vinyl acetate. The substance is rapidly removed from air by chemical breakdown, adsorption to airborne particles or aerosols, and wet deposition. Furthermore, air concentrations indicate a negligible risk with regard to ecotoxicity.

Non-compartment specific effects
Non compartment specific effects (secondary pois oning) of vinyl acetate are not expected as there is no indication that the substance has potentially bioaccumulative properties.
Marine Assessment including PBT assessment

VAM does not meet the PBT/vPvB criteria. A risk for the regional or local marine environment is not expected.

Hu man Health

Workers

Consumers

Man exposed indirectly via the environment

CAS No.: 108-05-4 67R059_0505_env Draft of 04.05.2005

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CAS No.: 108-05-4 81R059_0505_env Draft of 04.05.2005

CAS No.: 108-05-4 82

# RISK ASSESSMENT

Vinyl acetate

CAS-No.: 108-05-4

EINECS-No.: 203-545-4

Draft of 29.05.2008R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 2 Information on the rapporteur
Contact point:
Bundesanstalt für Arbeitsschutz und Arbeitsmedizin (BAuA) Anmeldestelle Chemikalien / Zulassungsstelle Biozide (Federal Institute for Occupational Safety and Health Division for Chemicals and Biocides Regulation) Friedrich-Henkel-Weg 1-25
44149 Dortmund (Germany)

fax: +49(231)9071-2679 e-mail: chemg@baua.bund.de

The first draft of the Comprehe nsive Risk Assessment Report of Vinyl acetate , a substance chosen from the EU 1 st Priority List in 1994, was discussed preliminary (written procedure) at the TM II / 2001 (June 2001).
The Environmental part was discussed in de pth at the TM III/2002 (August 2002) and further in depth at the TC NES IV 04 (December 2004). It was distributed for the last visit written procedure in May 2005 and for the final written approval in May 2006.
The Human Health part was discussed first in depth at the TM I/2002 (March 2002), second in depth at the TM IV/2002 (December 2002), last visit at the TM II/2003 (June 2003), 2 nd last visit (effects assessment only) at TC NES I/2007 and 2 nd last visit (Risk characterisation) at TC NES II/2007. It was distributed for the final written procedure in December 2007 and for a further written approval in May 2008.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 3 CONTENTS

0 OVERALL CONCLUSIONS/RESULTS OF THE RISK ASSESSMENT 5

1 GENERAL SUBSTANCE INFORMATION 8

2 GENERAL INFORMATION ON EXPOSURE 12

2.1 Exposure sources 12

2.1.1 Production 13
2.1.2 Processing 14

2.2 Uses 17

3 ENVIRONMENT 20

3.1 Environmental exposure Error! Bookmark not defined.

3.1.1 General discussion Error! Bookmark not defined.
3.1.2 Exposure Assessment for the Aquatic Compartment Error! Bookmark not defined.
3.1.3 Exposure Assessment for the Atmosphere Error! Bookmark not defined.
3.1.4 Exposure assessment for the terrestrial compartment Error! Bookmark not defined.
3.1.5 Non compartment specific exposure relevant to the food chain Error! Bookmark not defined
3.1.6 Regional concentrations Error! Bookmark not defined.

3.2 Effects assessment: Hazard identification and Dose (concentration) - response (effect) assessment Error! Bookmark not defined.
3.2.1 Effects assessment for the aquatic compartment (including sediment) Error! Bookmark not d
3.2.2 Effects assessment for the terrestrial compartment Error! Bookmark not defined.
3.2.3 Effects assessment for the atmosphere Error! Bookmark not defined.
3.2.4 Non compartment specific effects relevant to the food chain Error! Bookmark not defined.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 4 3.3 Risk characterisation Error! Bookmark not defined.
3.3.1 Aquatic compartment (incl. sediment) Error! Bookmark not defined.
3.3.2 Atmosphere Error! Bookmark not defined.
3.3.3 Terrestrial compartment Error! Bookmark not defined.
3.3.4 Non compartment specific effects relevant to the food chain Error! Bookmark not defined.
3.3.5 Marine Assessment including PBT Assessment Error! Bookmark not defined.

4 HUMAN HEALTH 21

4.1 HUMAN HEALTH (TOXICITY) 21
4.1.1 Exposure assessment 21
4.1.2 Effects assessment: Hazard identification and Dose (concentration) - response (effect) assessment 42

4.1.3 Risk characterisation 150

4.2 HUMAN HEALTH (PHYSICO-CHEMICAL PROPERTIES) 180
4.2.1 Exposure assessment 180
4.2.2 Effects assessment: Hazard identification and Dose (concentration) - response (effect) assessment 180

4.2.3 Risk characterisation 180

5 CONCLUSIONS / RESULTS 182

6 REFERENCES 185R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 5 0 OVERALL CONCLUSIONS/RESULTS OF THE RISK ASSESSMENT

CAS No. 108-05-4

EINECS No. 203-545-4
IUPAC Name Vinyl acetate

Overall results of the risk assessment:

( ) i) There is need for further information and/or testing

(x) ii) There is at present no need for furt her information and/or testing and for risk reduction measures beyond those which are being applied already

(x) iii) There is a need for limiting the risks; risk reduction measures which are already being applied shall be taken into account

Summary of conclusions:

Environment
As a follow up to conclusion (i), which was drawn in the first draft of the Environment Section of the Comprehensive Risk Assessment Report of Vinyl acetate (August 2002), further acute and long-term toxicity tests were performed for the aquatic compartment and more data on a number of production and processing sites were obt ained, leading to the following revised risk characterisation.

conclusion iii):

Terrestrial compartment
A risk to the local terrestrial compartment can be identified for the life cycle stage of vinyl acetate processing. This conclusion applies to th e generic processing scenario for the local main source. The unknown processing sites acc ount for a missing tonnage of 325,000 t/a (or 41 % of the total production volume of 800,000 t/a), compared to a verified processing tonnage of 475,000 t/a.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 6 The risk characterisations for selected (worst case) production and processing sites with site specific data indicate no actual risk to the terrestrial compartment. However, the highest PEC/PNEC ratio calculated with site specific da ta (0.86) is not very far from the PEC/PNEC ratio calculated for the generic processing scenario (2.33), and there was al so a risk at one of the production sites (which has been eliminated during the time of the preparation of this RAR). Consequently, it is not completely implausible that unknown processing sites pose a risk to the terrestrial environment.
The risk characterisation for the terrestrial compartment could still be revised by requesting further testing (i.e. OECD 207 Earthworm acute toxicity test and OECD 208 Terrestrial plants growth test). However, a further data improvement by means of testing is not considered a reasonable next step by the rapporteur for the following reasons. Further information on the toxicity of vinyl acet ate to terrestrial organisms allows for a reevaluation of the potential risk that emanates from the unknown processing sites, but delays risk reduction measures in case that a risk still remains with the new data. The rapporteur therefore proposes to enter directly into th e risk reduction phase, which would be more effective than further data improvement at this stage of the risk assessment.
Risk reduction measures should be considered fo r all facilities with a vinyl acetate processing capacity exceeding 20,000 t/a. This threshold is de rived from the generic processing scenario, assuming that vinyl acetate is released to so ils via sludge application and aerial deposition. Sites already applying advanced techniques woul d not require further consideration of risk reduction measures. It is known from some pr ocessing/production sites that techniques such as waste water distillation, sludge incinera tion or deposition in a landfill, waste gas incineration or vapour recovery systems can a void significant releases of vinyl acetate to soils. In principle, the rapporteur agrees with the proposal of SCHER that considering the volatility of the substance, terrestrial plants might be exposed via air. However, no guidance is available how to derive a PNEC for the air compartment. In addition, the available guidelines for terrestrial plants (OECD 208 / 227) are de signed to include exposure through soil or by wet residues (e.g. spray drift of plant production products). To determine effects of volatile compounds, testing needs to be conducted in closed greenhouses or chambers under continuous exposure conditions. We feel this ki nd of testing is not appropriate for vinyl acetate, because no indications for high toxicity for plants exist. For other soil organisms, a continuous exposure to volatile compounds like vinyl acetate is negligible since the substance is expected to evaporate from the soil.

conclusion ii):

Aquatic compartment
A risk to the local or regional aquatic comp artment (surface water and sediments) was not identified for production and processing of vinyl acetate. This conclusion applies to all sites.

Atmospheric compartment
Based on a qualitative risk characterisation, no unacceptable risk for the atmosphere is expected from vinyl acetate. The substance is rapidly removed from air by chemicalR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 7 breakdown, adsorption to airborne particles or aerosols, and wet deposition. Furthermore, air concentrations indicate a negligible risk with regard to ecotoxicity.

Non-compartment specific effects
Non compartment specific effects (secondary pois oning) of vinyl acetate are not expected as there is no indication that the substance has potentially bioaccumulative properties.

Marine Assessment including PBT assessment

VAM does not meet the PBT/vPvB criteria. A risk for the regional or local marine environment is not expected.

Human Health

Workers
conclusion iii)
Conclusion iii is expressed for the endpoint of carcinogenicity after dermal contact. Skin contact of vinyl acetate should be reduced at s cenario 2a (manufacturing of formulations and products, vinyl acetate monomer), even if ev aporation of the substance reduces the contribution of dermal exposure.
On the background of cancer risks and repeated dose toxicity, air concentrations of vinyl acetate at the workplace should be controlled to a level in the range of 17.6 mg/m 3 (critical exposure level). Conclusion iii is derived for repeated dose toxicity after inhalation for scenario 2 (manufacturing of formula tions and products). This scenario with an exposure value of 14.6 mg/m 3 is a borderline case. Since there is the uncertainty concerning the reduction of the intraspecies factor and th e mode of action for carcinogenesis for this borderline scenario conclusion iii is drawn.

Consumers conclusion ii)
There is at present no need for further info rmation and/or testing and for risk reduction measures beyond those which are being applied already

Man exposed indirectly via the environment
conclusion ii)
There is at present no need for further info rmation and/or testing and for risk reduction measures beyond those which are being applied alreadyR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 8 1 GENERAL SUBSTANCE INFORMATION

Identification of the substance

CAS No.: 108-05-4

EINECS No.: 203-545-4

IUPAC Name: Vinyl acetate

Synonyma: Acetic acid vinyl ester

Empirical formula: C 4 H 6 O 2

Structural formula:



## C H 2 

## CH
O CH 3 

## O

Molecular weight: 86 g/mol

Purity/impurities, additives

Purity: 99.8 % w/w

Impurities: ≥ 0.03 - 0.1 % w/w water

≥ 0.005 - 0.01 % w/w acetic acid

≥ 0.005 - 0.02 % w/w acetaldehyde
Additives: hydrochinone or hydrochinone mono methyl ether as stabilisator

0.00015 - 0.002 % w/wR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 9 Table 1-1: Physico-chemical properties

Physical state liquid at 20 °C Melting point - 93.2 °C Handbook of Chemistry and Physics, 1980 - 1981 Boiling point + 72.7 °C Merck Index, 1996 Relative density 0.932 at 20 °C Merck Index, 1996 Vapour pressure 120 hPa at 20 °C Hoechst AG, 1994c
Surface tension 24 mN/m at 20 °C (pure substance) Handbook of Chemistry and Physics, 1980 - 1981 Water solubility 20 g/l at 20 °C Merck Index, 1996 Partition coefficient logPow 0.7 Hoechst AG, 1992 Flash point - 8 °C (DIN 51755) CHEMSAFE, 1994 Auto-flammability, ignition temperature 385 °C (DIN 51794) CHEMSAFE, 1994

Explosive properties not explosive due to structural reasons Oxidizing properties not oxidizing due to structural properties

Vapour pressure: Vapour pressure values were available from safety data sheets, product information and literature without any details about the used methods. All values correlate well with the boiling point of 72.7 °C (Clausius-Clapeyron).

Water solubility: The water solubility is 20 g/l at 20 °C acco rding to safety data sheets and product information. No further information about the determination method is available.

Partition coefficient: According to literature data the partition coe fficient was determined experimentally (HPLC method: logPow 0.21, shaking method: l ogPow 0.73). The calculation with CLOGP3- Software resulted in a logPow of 0.7. Due to the agreement of experimentally and calculated values a logPow of 0.7 was used for the risk assessment.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 10 Classification

• (Classification according to Annex I)
F R 11 Highly flammable

• (Proposal of the rapporteur)

The current classification included in Annex I to Directive 67/548/EEC is only due to human health effects and does not yet consider envir onmental effects of vinyl acetate. Based on the data presented in the environmental section of this risk assessment report and the criteria of Directive 93/21/EEC, the rapporteur proposes the s ubstance not to be classified and labelled for environmental risks.

The classification included in Annex I to Di rective 67/548/EEC does not yet include toxic effects. According to the data presented belo w and the criteria of Directive 93/21/EEC, vinyl acetate should be classified as follows and assigned the risk phrases:

Harmful R 20 Harmful by inhalation

Irritant R 37 Irritating to respiratory system

Carcinogenic, Cat. 3 R 40 Limited evidence of a carcinogenic effect
Human data on irritation/corrosion caused by vinyl acetate are not available. In the only valid test (RCC, 2003) mild irritative effects on the sk in of rabbits was observed that do not need classification. The eye irritation potential of th e compound seems to be mild as judged on the basis of poorly documented eye irritation tests with rabbits. Hence, no classification for eye irritative effects is needed.

Acute inhalation tests with rats demonstrated se vere irritation in the respiratory tract of the animals. Thus, vinyl acetate should be labelled “R 37 Irritating to respiratory system”.
Results from an animal skin sensitization study (Buehler Test) showed a moderate skin sensitising potential of vinyl acetate (commercial grade). With the use of the Local Lymph Nodes Assay (LLNA) no significantly positive s timulation responses were detected at concentrations of 5% - 100%. Overall, the outco me of both studies may indicate that vinyl acetate is not devoid of a skin sensitising potential. The results of the LLNA do confirm the weak-moderate effects seen in the Buehler te st. However, since the positive threshold level was not exceeded in the LLNA, classification and labelling with R 43 is not warranted.
There is clear evidence for the carcinogenicity of vinyl acetate in two animal species and in both sexes. The carcinogenic potential was demonstr ated for the inhalation and oral route of administration. Vinyl acetate exposure produced tumo rs at the site of first contact along the exposure routes. A thresholded mode of carci nogenic action is thought to be active. The observed tumor responses are reflecting the target site-specific enzyme activities:R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 11 Following inhalation and oral exposure vinyl acetate is rapidly hydrolysed by carboxylesterases leading to the formation of acetic acid and acetaldehyde which is further converted into acetic acid in the presence of aldehyde dehydrogenases. Intracellular aldehyde dehydrogenase activity is limited, at higher con centrations of vinyl acetate it will not be sufficient for the oxidation of generated acetadehyde. Thus, at high vinyl acetate concentrations non-physiological concentrati ons of acetaldehyde are produced. Acetaldehyde is a physiological intermediate with low background concentrations. Its adverse effects (genotoxicity and mutagenicity) are limited to non-physiologically high concentrations. Therefore, a threshold mode of action is assumed for vinyl acetate.
Above threshold concentrations, cytotoxicity (only at the olfactory mucosa), mitogenic actions and genotoxic actions occurred.
Data on vinyl acetate are in line with the idea that vinyl acetate genotoxicity is mediated by acetaldehyde. Increasing concentrations of acetal dehyde produce genotoxic actions at the site of contact. It has to be taken into consid eration that acetaldehyde occurs naturally in mammalians cells and is part of the physiological cellular metabolism.

From animal data it is concluded that vi nyl acetate might pose a cancer risk for humans exposed to the substance via the inhalation or or al route. Carcinogenicity is thought to act via a secondary mechanism and the concern may only be relevant above threshold concentrations. The observed effects are thought to be releva nt for the human. For the respiratory tract humans may be less sensitive than the rat due to a lower carboxylesterase activity in the nasal

mucosa. In Germany, vinyl acetate is assigned to the MAK-pregnancy category "D" denoting that the current data base is not sufficient for final ev aluation of developmental toxicity. However it is outlined that vinyl acetate was evaluated for repr oductive toxicity in one species (rat) already with negative results. If this latter outcome c ould be verified in additional species vinyl acetate could be assigned to category "C" deno ting that no risk for adverse developmental effects have to be expected for female work ers in compliance with the respective MAK value of 10 ppm.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 12 2 GENERAL INFORMATION ON EXPOSURE

2.1 EXPOSURE SOURCES
Exposure of man and environment to vinyl acet ate monomer (VAM) may result from releases during each of the consecutive steps downstream the supply chain. These are production of the substance, polymerisation of the monomer, compounding operations involving the polymers, and eventually use of the end products.

Production synthesis of the monomer ▼
Use processing = (co)polymerisation of the monomer (co)polymers are marketed as dispersions, solid resins or solutions ▼ Compounding handling of the (co)polymers, e.g. manufacture of ready-to-use products like paints, adhesives, textile finishing agents, etc. ▼

---------------------------------------------------------------------------- End user manual end-user: e.g. painter man, floor layer, carpenter, etc. industrial end-user: e.g. printer, manufacturer of finished film ▼
Consumer e.g. painted walls, glued flooring, glued furniture, printed card, packed food, etc.

The first three stages in the chain, i.e. manufacture of the monomer, polymerisation of (co)polymers, and compounding of (co)polymers are in most cases conducted by different companies and at separate locations. Notwithst anding, there is a small number of sites where both production of the monomer and further polymer izing is carried out, while there are other cases where VAM is (co)polymerized and subsequently also compounded.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 13 Only a few manufacturers of VAM exist in the EU, whereas the number of companies polymerising the monomer and in particular the number of downstream users of the polymers is considerably higher. For example, there are no more than two VAM manufacturers in Germany that use parts of the produced VAM volume to manufacture vinyl acetate (co)polymers. Similarly, just six out of fifty- three European manufacturers of coating/printing inks manufacture the required polymer constituents from the monomer on-site.
Production sites of VAM and facilities produci ng the (co)polymers, but also compounding operations are typical point sources of VAM emissions. Any VAM entering the environment from the latter type of operation results from releases of monomer residuals remaining with the processed (co)polymers.
Finally, diffusive releases of residuals may occu r during end-use of the finished products that contain vinyl acetate (co)polymer constituents.

2.1.1 Production
Vinyl acetate is produced by a catalytic vapour- phase reaction of ethylene and acetic acid in gas phase, liquid phase or a fluidised-bed process.

2.1.1.1 Global production figures
The worldwide demand for VAM reportedly am ounted to 4.3 million t/a in 2003, representing an overall operating rate of about 86 % of a maximum global production capacity of 5 million t/a. The main production capacities are located in Asia (43 %) and North America (34 %), followed by Western Europe on third rank (18 %) (Chemical Week, 2003).

2.1.1.2 Production in Western Europe
A questionnaire was launched by the European Chemical Industry Council (CEFIC) among member companies in 2000 and updated in 2002 to collect data on produced and processed volumes of vinyl acetate monomer in Europe. Fi ve producers of VAM were identified with a nominal production capacity of 800,000 t/a (cf. Table 2-1). Fluctuating operating rates (additional capacities brought online, partly o ffset by shutting down other plants) make it difficult to provide a general figure for the annual production volume of VAM in the EU.
For comparison, the production volume of VAM reported by the CEFIC Acetyls Sector Group (ASG) for Western Europe was a bout 715,000 tonnes in 2002. Additionally, total purchases 1 in 2002 accounted for almost 250,000 t onnes. Along with an opening stock 2 of approximately 80,000 tonnes, the “total supply” for 2002 amounted to 1,045,000 tonnes.

1 Purchase from outside Western Europe but also from co-producers in Western Europe
2 Includes all product produced or purchased but not yet invoiced or transferred to internal captive use, e.g. product in storage or in transit (should be equal to the closing stock of the previous period).R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 14 From the total supply of about 1,045,000 tonnes, some unquantified amounts were exported outside Western Europe again (figures were not given by industry for confidentiality reasons). With an end stock 3 of less than 50,000 tonnes in 2002, approximately 750,000 tonnes of VAM were marketed in Western Europe that year (all figures provided by CEFIC ASG).
The outcome of the CEFIC survey was in poor consistency with data retrieved from the IUCLID database (as of May 1999). A number of the companies included in the CEFIC survey were not covered by the IUCLID data - and vice versa. Several of the enterprises had discontinued to exist as a business entity, owing to an intensive restructuring process of the market (mergers, acquisitions and divestitures of business segments). In some cases it turned out that some IUCLID-mentioned capacities ha d been only sales bureaus, whereas other facilities had meanwhile been shut down. IUCLID data were therefore left aside.

2.1.2 Processing
Unlike for production, no exact figure of the pr ocessed volume of vinyl acetate can be extracted from the statistics provided by the CEFIC Acetyls Sector Group (ASG). The provided data is difficult to balance for impor t/export and purchases/sales as ASG statistics comprise all Western European countries, whic h does not coincide with EU countries, and some parts of the statistics are confidential, thus were not disclosed to the rapporteur.
According to the CEFIC Acetyls Sector Group, the total supply of VAM in Western Europe was approximately 1,045,000 tonnes in 2002, ba sed on a production volume of about 715,000 t, total purchases of about 250,000 t and an opening stock of about 80,000 t. When exports, sales, captive use and closing stoc k are deducted, approximately 750,000 t entered the open market in Western Europe in 2002. From this tonnage, an unknown amount is sold to non-EU countries in Western Europe (Switzerland, Turkey, Iceland, Norway), with the remaining tonnage of VAM bei ng sold and processed in the EU. Some amounts of the total VAM supply of 1,045,000 tonnes is directed to captive use 4 and also processed in the EU, but figures on captive use are not provided. As sales to non-EU countries in Western Europe and captive use were not quantified, the exact processing volume in the EU cannot be determined. It is therefore assumed to be in the range of 750,000 – 800,000 tonnes per year.
Responses to the CEFIC questionnaire came eith er from individual processors or industry associations of processing companies. One industry association (CEPE) did not provide information broken down to individual members or processing sites, but for reasons of confidentiality submitted aggregated, in part statistically evaluated data (max./min. values or average means) which were compiled from a questionnaire among member companies. In addition to the CEFIC data, other processing s ites could be identified and consulted. Based on this data collection, the actual total processing volume of VAM may amount to 474,900 tonnes per year in the EU (cf. Table 2-1).

3 Closing or end stock of the previous period. Includes all product produced or purchased but not yet invoiced or transferred to internal captive use, e.g. product in storage points or products in transit.
4 All product transferred internally in Western Europe whether from own production or purchased.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 15 Figure 2-1 Market statistics of VAM for 2002, based on CEFIC Acetyls Sector Group.

It has to be concluded that the data provi ded on production and processed volumes of VAM do not match very well:

Based on single sites: Based on market statistics :
Production 800,000 tonnes 715,000 tonnes Processing 474,900 tonnes 750,000 - 800,000 tonnes (estimate)

This imbalance may be due to a number of reasons:

 Figures on volumes were reported for di fferent business years and reflect the dynamics of a market which is characterized by continuous restructuring activities

 Some annual production data are based on nominal capacities, thus do not reflect actual figures which may change from year to year

 Production figures are rounded to nearest 10,000 t/a

 Downstream users did not reply to the questionnaire

 Data are not corrected for import/export or sales/purchasesR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 16 The maximal difference between reported produc tion volume and specific processing data for individual sites is 325,000 t/a (= 800,000 t/a - 475,000 t/a). It is therefore assumed that a number of processing sites exist that were not covered by the CEFI C questionnaire. As no information on these sites is available, a ge neric risk characterization will be conducted. A fraction of main source of 0.15 and 300 emission da ys are assumed (Tab. B3.2 of the TDG) to estimate the fraction of the total emissions that is expected to be released through the main local point source (worst case scenario for the local environment). The estimated total emissions that are released during processi ng of the total volume of 325,000 t/a are included in the calculation of the regional and continental background concentrations.
Specific local risks were calculated for the production and processing sites that could be identified (cf. Table 2-1). In several cases it could not be clarified whether the term “use” in the questionnaire was interpreted by the responde rs as (co)polymerisation, or compounding of already polymerised material, or both. If not sp ecified otherwise it was assumed that the data referred to (co)polymerisation, although this may overestimate emissions in some cases. For confidentiality reasons, sites were coded. Fi ve producers of VAM were identified being located in four EU member states (France, Germany, Spain and UK). Identified processing plants are located in Belgium, Denmark, Fi nland, France, Italy, Germany, the Netherlands, Spain and UK. No information on geographi cal locations was disclosed by industry associations that provided only aggregated data.

Table 2-1: Production and/or processed volumes of VAM identified within the EU

Site code Produced volumes Processed volumes Data source 1 30,000 CEFIC 2 10,000 CEFIC 3a 6,000 CEFIC/CIRFS 3b 10,000 CEFIC/CIRFS 3c 8,000 CEFIC/CIRFS 3d 4,000 CEFIC/CIRFS 4 110,000 CEFIC 5 90,000 CEFIC 6 25,000 CEFIC 7* 10,810 CEPE 8 15,000 CEFIC 9 9,100 CEFIC 10 15,000 CEFIC 11 110,000 CEFIC 12 36,000 CEFIC
13 280 CEFIC 14 2,000 CEFIC/FEICAR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 17 Site code Produced volumes Processed volumes Data source 15 2,200 CEFIC/FEICA
16 400 CEFIC/FEICA
17 300 CEFIC/FEICA 18 14,000 CEFIC/FEICA 19 25,000 CEFIC/FEICA
20** 0 0 CEFIC/FEICA 21 200,000 CEFIC 22 100,000 CEFIC 23 17,000 CEFIC 24 5,000 pers. communicated 25 6,910 pers. communicated 26 140,000 pers. communicated 27 250,000 pers. communicated 28 8,000 pers. communicated 29 6,500 pers. communicated 30 8,400 pers. communicated ∑ 800,000 474,900
CEFIC: European Chemical Industry Council CEPE: Conseil Européen des Industries des Peintures, Encres d’Imprimerie et Couleurs d’Art CIRFS: Comité International de la Rayonne et des Fibres Synthetiques FEICA: Fédération Européenne des Industries de Colles et Adhésifs * As communicated by industry association CEPE, most manufacturers buy polymer emulsions (PVA) ready for use and do not polymerise VAM themselves: 52 companies reported in a questionnaire to use PVA at 116 different sites for making printing inks, paintings and coatings. The total volume of VAM polymers was 43,524 t in 2000. The processing volume in the table re fers to the two companies still polymerising VAM. ** confirmation of conducting merely compounding ope rations, i.e. handling of the (co)polymers.

2.2 USES
Vinyl acetate monomer is solely used as an intermediate in chemical industry for manufacturing (polymerisation) of vinyl acetat e (co)polymers (IC 3 / UC 33). Hence it is concluded that the entire production volume of VAM is used up for the manufacture of various (co)polymers, mainly polyvinyl acetate.
Apart from manufacture of homopolymers the m onomer is combined with other monomers like ethylene, vinyl chloride and acrylic acid es ters to form various types of co-polymers. According to the Directory of Chemical Pr oducers Western Europe (SRI International, 1997/98) two types of co-polymers involving ethylene are produced:R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 18 A. ethylene-vinyl acetate co-polymer resins (EVA) with a production capacity of approximately 1 million t/a, and

B. vinyl acetate-ethylene co-polymer resins (VAE) with a production capacity of approximately 300,000 t/a.
Polymers manufactured from VAM are used in a broad spectrum of products, including water-based paints, printing inks, lacquer, cer amic, adhesives for packaging and construction, paper finishing, and protective colloids for va rious materials. Other important products include textile fibres, paper coating and inks (Table 2-2). The content of residual VAM in homo- and co-polymers depends on the product, sp anning a wide range of reported values of less than 5 ppm up to 6,000 ppm (Celanese, 2000) . According to the CEFIC compilation of data from industry, the majority of polymer s have an average content of around 1,000 - 2,000 ppm or less. Ullmann (1998) provides a quan titatively weighted median value for the monomer content of roughly 3,000 ppm. The latter value will be used for estimating diffuse releases of VAM from (co)polymers and end-use products in this document.
In addition, vinyl acetate (co)polymers are used as feedstock for manufacture of vinyl alcohol (co)polymers (e.g. polyvinyl alcohol). Polyvinyl alcohol is obtained by hydrolysing polyvinyl acetate. The production capacity w ithin the EU is reported at > 100,000 t/a (SRI International, 1997/98). Commercial grades of polyvinyl alcohol differ in the degree of polymerisation (molecular mass) and degree of hydrolysis (re sidual polyvinyl acetate content). Along with saponification (alkaline hydrolysis of fatty aci d esters) of the acetyl moieties of polyvinyl acetate, monomer residuals are getting eliminat ed as well. A minor fraction of polyvinyl alcohol ends up in the manufacture of polyvinyl acetales, e.g. of polyvinyl butyral (PVB).
A broad quantitative breakdown of the use pattern of vinyl acetate is available for Germany for 1990. In this year, approximately 68 % of th e produced vinyl acetate was used mainly for the manufacturing of polyvinyl acetate and, to a less extent, for the manufacturing of copolymers. 32 % of the produced vinyl acet ate was manufactured to polyvinyl alcohol (BUA, 1993). Vinyl acetate occurs as residual monomer in homo- and copolymers based on vinyl acetate and in products or formulations based on these polymers. As polyvinyl alcohol is produced by trans esterfication (saponifica tion) of vinyl acetate (co)polymers, residual vinyl acetate monomer does not occur in polyvi nyl alcohol and in polymers derived from polyvinyl alcohol (Celanese, 2000). Hence the manufacturing of polyvinyl alcohol is not relevant in the context of residual monomer content.

Use pattern of vinyl acetate:

Main category Industry category Use category Non dispersive use Chemical industry: used in synthesis (IC 3) Intermediate: monomer in the production of polyvinyl acetate (UC 33)R059_0805_env_hhDraft of 29.05.2008CAS No.: 108-05-419Table 2-2:Vinyl acetate in the value chain: (co)polymers are usedin a wide spectrum of products (Wacker Chemie, 2002)

Building material Printing ink Paint Film Lacquer Adhesive Cosmetic, hairspray Plastic Paper finishing Textile finishing Non

wovenVAM + VAMÆpolyvinyl acetatex x x x x x x xVAM + acrylateÆvinyl acrylic co-polymerx x x x xVAM + ethyleneÆEVAx x xVAM + ethyleneÆVAEx x x x x x xVAM + vinyl chlorideÆVC copolymerx x x x x xVAM + carbonic acidÆVA carbonic acid copolymerxVAM + vinyl esterÆVA vinyl ester copolymerx x xR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 20 3 ENVIRONMENT
See separate rar.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 21 4 HUMAN HEALTH

4.1 HUMAN HEALTH (TOXICITY)

4.1.1 Exposure assessment

4.1.1.1 General discussion
Vinyl acetate is a monomer, solely used to manufacture vinyl acetate (co)polymers. For production volumes see section 2.
A quantitative breakdown of the use pattern is available for Germany, where in 1990 app. 68 % of the produced vinyl acetate was mainly used for the production of polyvinyl acetate and, to a less extent, for the production of c opolymers. 32 % of the produced vinyl acetate was manufactured to polyvinyl alcohol (BUA, 1993).
Vinyl acetate occurs as residual monomer in homo- and copolymers based on vinyl acetate and in products / formulations based on these polymers. As polyvinyl alcohol is produced by trans-esterfication (saponification) of vinyl acetate (co)polymers, residual vinyl acetate monomer does not occur in polyvinyl alcohol a nd in polymers derived from polyvinyl alcohol (Celanese, 2000).
The content of residual vinyl acetate monomer in homo- and copolymers depends on the product and the field of application (< 2 - 3000 ppm, Celanese, 2008). The quantitatively weighted median value of this content amounts to 3000 ppm (Ullmann, 1998).
Polymers based on vinyl acetate are ingredients of a variety of products, which are applied in e.g. adhesives, paints, fillers, coating materi als, plasters and primers for porous building materials in the construction industry and in finishing agents (Ullmann, 1998).
For workers exposure to vinyl acetate occurs primarily via inhalation of the vapour and by immediate dermal contact with the substance.
There is no direct consumer use of vinyl acet ate monomer. However, consumer exposure may result from the use of polymerized vinyl acet ate products containing very small amounts of residual monomer such as binders and additives for paints and plasters, glues (e.g. for carpets or structural members), and coatings.
Among 42 products listed in the Swedish product register which contain vinyl acetate, 6 products were found to be used by consumers. In the Norwegian product register, 15 products which contain vinyl acetate have been listed for use in the consumer field.
In the Federal Republic of Germany, products containing polyvinyl acet ate in which vinyl acetate may be present as a residual monomer are used in the consumer field. Thus, the consumer may be exposed to vinyl acetate; the exposure may take place via the inhalation, dermal and oral routes.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 22 Vinyl acetate may be released to the environment, principally to the atmosphere, as a result of emissions from manufacturing, processing, and st orage facilities. The short atmospheric halflife, the rapid hydrolysis in water, the low n-oc tanol/water partition coefficient, and the ability of biological fluids of mammals and other organisms to degrade vinyl acetate will lead to rapid removal. Little or no vinyl acetate is det ected in environmental samples, including those from hazardous waste sites (VATG, 1994).

4.1.1.2 Occupational exposure
The exposure assessment generally aims at assessing exposure levels representing the reasonable worst case situation. The reasonable worst case is regarded as the level of exposure which is exceeded in a small percentage of cases over the whole spectrum of likely circumstances of use for a specific scenario. For scenarios with the reasonable worst case estimates leading to a risk, in addition, typical values are assessed, if the necessary information is available. The typical exposure is an estimate of the approximate location of the median levels of exposure over the w hole spectrum of likely circumstance. The combination of both levels gives an impression on the distribution of the exposure levels for a specific scenario and might serve as an extended basis for a comprehensive risk characterisation and for the discussion of risk reduction measures.
The assessment of inhalation exposure is main ly based on measured exposure levels from which – if possible – 90 th percentiles are derived as representing reasonable worst case situations. For the purpose of exposure assessm ent only data measured later than 1990, if available, are taken. Scenarios are clustered as far as possible to make the description transparent. Beside inhalation exposure, dermal exposure is assessed for each scenario. Two terms can be used to describe dermal exposure: Potential dermal exposure is an estimate of the amount of a substance landing on the outside of work wear and on the exposed skin. Actual dermal exposure is an estimate of the amount of a substance actually reaching the skin. There is an agreement between the EU-membe rstates, within the framework of existing substance, to assess - as a rule - dermal e xposure as exposure to hands and parts of the forearms. In this, the main difference betw een both terms – potential and actual - is the protection of hands and forearms by work w ear and – more important – the protection by gloves. Within this exposure assessment, the exposure reducing effect achievable by gloves is only considered if information is provided, that for a certain scenario gloves are a widely accepted protective measure and that the glove s are fundamentally suitable for protection against the substance under consideration. As a m easure for the latter, tests according to DIN EN 374 are taken as a criteria. For most down stream uses it is commonly known, that gloves are not generally worn. In these cases, dermal exposure is assessed as actual dermal exposure for the unprotected worker. Since often quan titative information on dermal exposure is available, the EASE model is used for assessing dermal exposure, at the most.
Industrial activities involving monomeric vinyl acetate present opportunities for exposure. Exposure ranges depend on the particular operation and the risk reduction measures in use.
The following occupational exposure limits (OEL) and short term limits (STEL) apply in the EU and the USA:R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 23 Table 4.1.1.2.: Occupational exposure levels (EU, USA)

Country OEL STEL Source Finland 36 mg/m 3 (10 ml/m 3 ) 71 mg/m 3 (20 ml/m 3 ) FIN, 2007 Austria, Greece 36 mg/m 3 (10 ml/m 3 ) 70 mg/m 3 (20 ml/m 3 ) A, 2007, GR 2001 Belgium, Spain 36 mg/m 3 (10 ml/m 3 ) 54 mg/m 3 (15 ml/m 3 ) B 2007, SP 2008 USA: ACGIH, Italy, Portugal 35 mg/m 3 (10 ml/m 3 ) 53 mg/m 3 (10 ml/m 3 ) USA, 2008, I, 2008, POR, 2004 Ireland 30 mg/m 3 (10 ml/m 3 ) 60 mg/m 3 (20 ml/m 3 ) IRL, 2007 Denmark, France, Norway 30 mg/m 3 (10 ml/m 3 ) - DK, 2007, F, 2008, NO, 2007 Sweden 18 mg/m 3 (5 ml/m 3 ) 35 mg/m 3 (10 ml/m 3 ) S, 2007 Germany, The Netherlands 18 mg/m 3 (5 ml/m 3 ) - GER, 2007, NL, 2007

Occupational exposure to vinyl acetate may occur in the following areas:
- production of vinyl acetate and polymerisation in the chemical industry (scenario 1), - manufacturing of formulations and products (scenario 2), - use of formulations and products containing residual vinyl acetate (scenario 3).
For the manifold uses of vinyl acetate (co)polymers with residual vinyl acetate monomer content < 2 – 3000 ppm, low levels of exposure are to be expected. In spite of this, on account of the carcinogenic effect of vi nyl acetate, these scenarios are included in the occupational exposure assessment. Due to hydrolysis of vi nyl acetate monomer, a further decrease of the residual monomer content occurs.
Exposure during the skilled trade use of hair care products (3 w/w vinyl acetate copolymer) and car polishing products (1.5 w/w vinyl acetate copolymer) are regarded to be of minor relevance since the monomer concentrati on is approx. 100 times below the polymer concentration. Therefore these scenarios are not included in this occupational exposure assessment.

4.1.1.2.1 Production of vinyl acetate and poly merisation in the chemical industry (scenario 1)
Vinyl acetate is produced by a vapour phase reac tion between ethylene and acetic acid in the presence of a palladium catalyst or between acetyl ene and acetic acid in the presence of a zinc acetate catalyst (Zenz and Cordaso, 1994). The s ubstance is manufactured continuously in closed systems at increased temperature and high pressure. It is to be assumed that the substance is processed daily. Consequently the duration and frequency of exposure are assumed to be daily and for the entire length of the shift. According to information providedR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 24 by one producer, filling devices are equipped with local exhaust systems and, for the purpose of dispatch, vinyl acetate is filled into tank cars by means of a gas displacement device.
Vinyl acetate is used primarily to produce pol ymers like polyvinyl acetate, polyvinyl alcohol (via transesterification (saponification) of polyvinyl acetate), and a variety of copolymers. According to information provided by the produ cers, the polymerisation process takes place discontinuously or continuously in a closed sy stem (Celanese, 2000). These polymers, usually formed as emulsions, suspensions, solutions, or re sins are used to prepare different products e. g. adhesives, paints, paper coatings and textile finishing agents (Zenz and Cordaso, 1994). In part, the further processing is performed imme diately after production, so that transfer or filling activities are avoided to a large extent.
The other main use of vinyl acetate is th e production of polyvinyl alcohol being also performed in closed systems. Residual vinyl acetate monomer does not occur in polyvinyl alcohol and in polymers derived from polyvinyl alcohol (Celanese, 2000).
Since vinyl acetate is highly flammable it is to be expected, that high exposure levels at the workplace are avoided. For the large-scale chemi cal industry high standards of control at the workplaces are assumed to be practised even if the containment is breached. According the information provided by the companies, exposur e is possible during sampling, maintenance, transfer, charging of catalysts, filter changi ng, drumming and cleaning. Inhalation exposure in other areas is normally minimised by techni cal equipment (e.g. special designed filling stations, local exhaust ventilation).
Workers normally use PPE (gloves, eye glasse s) and, during cleaning activities, respiratory protection in addition (Celanese, 2000).R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 25 Inhalation Exposure
Workplace measurements
Table 4.1.1.2.1: Vinyl acetate exposures at wor kplaces in the chemical industry during production and polymerisation

Job category / activities Year of

measurement Number of samples Range of measurement data [mg/m 3 ] Geometric

mean [mg/m 3 ] 95thpercentile

[mg/m 3 ] Duration and frequency

8-h time weighted average

Production
maintenance sampling, loading production 1992

- since 1978 2 6/year

(p) 3/year < 1.8 – 3.5
0.2 – 1.4

< 17.8 -

-

- -

-

- -

-

-

Polymerisation since 1994
1997 –1999
1994 – 1999
1994 – 1999

1995 – 2000 427 20 (s) 265 (p) 38 (p)

5 0 – 22.9
0.007 – 4.5
<0.006 – 11
<0.004 – 2.4
2.6 0.2
0.1
<0.03
<0.03

- 2.6
2.9
0.4

2

- -

-

-

-

-

Polyvinyl alcohol production - 2/year (p) 0.2 – 1.4 - -

Short term values

Production
Maintenance 1997 2 < 2 – 3.9

- - - p: personal sampling; s: stationary sampling
For the purpose of measuring vinyl acetate in the air at the workplace, the substance is adsorbed to activated charcoal and then deso rbed using carbon disulphide and determinated gas-chromatographically. The detection limit of the method amounts to 0.09 mg/m 3 (sampling volume: 25 l) (BASF AG, 1999).
Due to the measurement method and the sampli ng strategy which were applied, the currently available measurement results (Table 4.1.1.2.1.) are regarded as valid.
Three producers provide information on the coll ective of exposed workers: 35 – 40 workers. From the descriptions it is concluded that the exposure scenarios relating to the production and the polymerisation of vinyl acetate can be clustered. The collectives of measurement results comprise exposure levels from 0 – 22.9 mg/m3 with four 95 th percentiles up to 2.9 mg/m3. From the data given in tabl e 4.1.1.2.1 regarding production and polymerisation,R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 26 3.0 mg/m3 (based on 95 th percentile of 2.9, round off) is de rived as the reasonable worst case of inhalation exposure in the chemical industry.

Conclusions

For the assessment of risks of inhalation e xposure to vinyl acetate during the production and polymerisation in areas with high levels of pr otection belonging to the chemical industry an 8-h time weighed average concentra tion (8-h TWA) of 3.0 mg/m3 (95 th percentile, round off) should be taken to represent a reasonable worst case situation.

Dermal exposure When producing and polymerising vinyl acet ate dermal exposure could occur during activities like drumming, sampling, cleaning, maintenance and repair work. For the unprotected worker, according to the EASE mode l, potential dermal exposure is assessed as follows:
Input parameters: Non dispersive use, direct handling, intermittent Level of exposure: 0.1 – 1 mg/cm 2 /day.
Considering an exposed area of 420 cm 2 (palms of hands) the model yields an exposure level of 42 - 420 mg/person/day.
For assessing actual dermal exposure levels, it ha s to be considered that the substance is manufactured and further processed primarily in closed systems and that the use of PPE (here gloves and eye protection) during exposure rele vant activities is highly accepted in the largescale chemical industry. The extent of protec tion by PPE (here gloves) depends inter alia on the suitability of the recommended material with regard to the permeation properties of substance.
According to information provided by the manufact urers, in case of vinyl acetate, suitable gloves (tested according EN 374) are worn. Furt her information shows that the permeation time of the recommended gloves is longer than normal operation activities length (vinyl acetate handling is less then 30 minutes per shif t). Apart from this the gloves ought to be changed immediately by extensive contamination with vinyl acetate.
The exposure assessment is made based on the a ssumption, that a vast majority of workers belonging to scenario 1 are protected by suitable gloves. However, in spite of this, dermal exposure may occur due to e. g.
- unintended contamination during the handling of used gloves, - limited protection of suitable gloves at real working conditions (e. g. mechanical stress).
As a rule, for the use of suitable gloves, low levels of daily dermal exposure are to be expected. Since no measurement results are availa ble, a protection efficiency of 90 % is taken as a default value leading to an exposure level of 42 mg/person/day.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 27 Besides in the case of vinyl acetate, the pr edominant effect reducing potential dermal exposure is the very high volatility of the substance (vapour pressure 12 kPa) which leads to considerable low retention times of the substan ce on the skin or on the protective gloves. This exposure reducing effect cannot be considered if workers have continuous direct contact with the substance, e.g. dipping hands into the subs tance. For using vinyl acetate as a chemical intermediate, this situation (occlusive exposur e) is regarded to be rather non-probable. Furthermore, it is assumed, that non-occlus ive exposure is the predominant exposure situation. In annex 1, the calculation of the evaporation time of the pure substance is described. For vinyl acetate with the EASE estim ate of 1 mg/cm2, an evaporation time of 10 second (T = 30°C) is calculated. For vinyl acetate on the gloves, an assumed temperature of 20°C leads to a similar evaporation time. This values should be regarded to represent the order of magnitude, since it is not known in how far the interaction of the skin with the substance influences the evaporation time.
In conclusion, the short retention time of vinyl acetate on the skin leads to considerably lower dermal exposures than predicted by the EASE model which considers dermal exposure during the whole shift (0 – 42 mg/person/day).

Conclusions
For assessing the health risks from daily de rmal exposure in the area of production and polymerisation (scenario 1), an exposure level of 0 – 42 mg/person/day should be taken. The higher level is regarded to represent the reasonable worst case situation. This exposure assessment is based on the information provided by the producers, that suitable gloves are worn and takes into account the possible dermal exposure under actual workplace conditions.
On account of the high vapour pressure of vinyl acetate, the resulting retention time of the substance on the gloves or the skin is shortened and lower levels of dermal exposure than the estimated one are to be expected.
Exposure to the eyes is largely avoided by using eye protection.

4.1.1.2.2 Manufacturing of formulations and products (scenario 2)
According to information provided by industry ther e is normally no direct use of vinyl acetate monomer in formulating facilities and exposur e is limited to the use of vinyl acetate (co)polymers containing small amounts of resi dual monomer. Vinyl acetate monomer itself is not used in formulations. However, some adhesive producing facilities use vinyl acetate monomer for (co)polymerisation and perform the adhesive formulation subsequently. Therefore, this exposure scenario comprises the polymerisation step (use of vinyl acetate monomer) and the formulation step (residual vinyl acetate in (co)polymers).
The content of residual vinyl acetate monom er is < 2 - 3000 ppm in the different (co)polymers. It depends on the further appli cation of the (co)polymer. During the further processing of the (co)polymers, residual monomer may be released. The content of residual vinyl acetate monomer in water-based systems decreases by hydrolysis (BUA, 1993).R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 28 Formulations and products based on vinyl acet ate (co)polymers like adhesives and paints contain < 2 - 3000 ppm residual vinyl acetate monomer, which normally evaporates when applied by the end user.
The processing to various products (formulation e.g. adhesives, paints) may not be limited to the large-scale chemical industry but occurs in small and medium-sized chemical companies, too. For this case, in principle, it cannot be excl uded that, in addition to the level of technical protection described for the large scale i ndustry, open systems without local exhaust ventilation are used (Voullaire and Kliemt, 1995). According to this scenario, higher inhalative and, as a result of the non regular use of gloves, higher dermal exposures are expected if vinyl acetate (co)polymers a nd compounds are handled, e.g. during filling, sampling, charging, cleaning, maintenance and re pair works. Vinyl acetate monomer is normally handled in closed systems, but some tasks, e.g. pumping and filling, are performed using the monomer.

Inhalation exposure

Workplace measurements
Measurement data is only available from the adhesive production.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 29 Table 4.1.1.2.2: Vinyl acetate exposures at workplaces for adhesives production

Job category / activities Years of

measurement Number of samples Range of measurement data [mg/m 3 ] 50 th percentile

[mg/m 3 ] 90 th percentile

[mg/m 3 ]

Adhesives production

Formulation (FEICA, 2001) (no information on sampling and duration of sampling) 1997 – 2000
1995 – 2000 1996, 2000 1998, 1999

1995 60
100

2

-
1 0.07 – 32
10.3 – 14.6

1.8 - 3.9
3.2 – 46

3.1 3.9
12.5

-

- -

-

-

-

Pumping of monomer vinyl acetate into tank Preparation of pre-emulsion

Pumping of pre-emulsion into reactor 1998, 1999

1998, 1999

1998, 1999 -

-

- 39 – 46.8 (30 min)

< 3.6 (90 min)
18 (60 min) -

-

- -

-

-

8 h time weighed averages Filling, cleaning, opening of reaction vessels (BGAA, 1996 and BG Chemie 2002) 1990 – 1995
1996 – 2002 10 (p)
23 < 64

- 6
3.1 56
14.6

p: personal sampling
According to information provided by the adhesive producers 2 – 70 workers are exposed.
Most of the data given in table 4.1.1.2.2 cannot be regarded as shift averages but - with some restrictions as exposure during activities, which do not last the whole shift.
The data regarding adhesives production (table 4.1.1.2.2) shows one measurement collective with results from 10.3 - 14.6 mg/m3 and a 50 th percentile of 12.5 mg/m3. But there are also measurement collectives with wide ranges from 3.2 mg/m3 to 47 mg/m 3 . The sampling durations are in part given as 30 min – 60 min. Calculated shift averages thus amount to 2 – 3 mg/m3. The highest measured result was obtained during pumping vinyl acetate monomer into a monomer tank.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 30 Measurement results from workplaces in the a dhesives industry with partly lower level of protection obtained during filli ng, cleaning and opening of reaction vessels were provided by the German Employer’s Accident Liability Insurance Association (BGAA, 1996 and BG Chemie 2002,, c.f. table 4.1.1.2.2). It can be s een, that measurement data obtained 1996 – 2002 are considerably lower than those obtained 1990 – 1995. The 90 th percentile of 56 mg/m3 is reduced to 14.6 mg/m3. It is descri bed that the two highest results (56 mg/m3 and 64 mg/m3, 1990-1995) were obtained during polymer isation of monomer vinyl acetate, in part with not sufficient control measures in place. If necessary, the situation has been changed by the companies. BGAA states, that the old da ta were in part worst case measurements. Taking into accpunt, that the new data were obtai ned in 10 companies, they can be regarded as representative for the exposure situation.
Workplace measurements obtained during the manufacture of polymer dispersions in adhesive production facilities have been submitted by the Federal Monitoring Authorities in Germany for the period 1990 – 1993. Air measurem ents revealed concentrations between < 0.1 – 40mg/m 3 (n = 10, personal sampling) w ith a mean value of 22 mg/m 3 . A higher value of 70 mg/m 3 was obtained with stationary sampli ng. The second highest value amounts to 40 mg/m 3 . The workplaces were only partially equi pped with local exhaust ventilation. Since only limited information is available on the resu lts, the measurement results are not included in table 4.1.1.2.2.
Taking into account the short term exposures of up to 46.8 mg/m3, the shift averaged given by BGAA seems to be quite plausible. Based on the available measurement results, 14.6 mg/m3 (90 th percentile of a collective of measured results ) is regarded to represent a reasonable worst case situation in the adhesive production industr y. In addition, a short term exposure level of 47 mg/m3 should be taken for assessing the risks of daily inhalation exposure.

Conclusions
At present, the information on exposure leve ls in the formulation industry is limited. Measurement results are available from the adhesive production only. This fact might indicate that exposure levels are at highest in this industrial sector and possibly lower in the formulation of paints. However, the available in formation cannot be seen as a proof for this assumption.

The available exposure levels indicate that exposure up to 46 mg/m3 (see table 4.1.1.2.2) (maximum value 70 mg/m3, see text on data from the Federal Monitoring Authorities) occurs. The high exposure level indicates that monomeric vinyl acetate is handled in the adhesive producing companies (polymerisation step).
For assessment of the health risks from daily inhalation exposure to vinyl acetate during the formulation of products (here: adhesives), an 8-h time weighed average concentration (8-h TWA) of 14.6 mg/m3 (90 th percentile of a measurement collective) should be taken to represent a reasonable worst case situation. It should be noted that considerably lower exposure levels are to be expected if only the formulating step is performed (no handling of monomer vinyl acetate).R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 31 Short term exposures up to 47 mg/m3 (duration 30 min) obtained during the handling of vinyl acetate monomer, e.g. pumping into storage tanks, should be taken into account.

Dermal exposure
According to the description given above, the use of vinyl acetate monomer (polymerisation step) is regarded to represent the reasona ble worst case situation. The exposure level estimated for handling (co)polymers with residua l monomer (formulation step) is appropriate for the typical exposure.
For the handling of vinyl acetate monomer as well as (co)polymer (residual monomer: < 3000 ppm) during the compounding of formulations a nd products (e.g. adhesives) in small and medium-sized chemical enterprises it cannot be excluded that gloves and eye protection are not regularly worn and that both, immediate de rmal contact and exposure to eyes caused by hand-eye-contacts occur. Dermal exposure is assessed for the unprotected worker using the EASE model:
Input parameters: non-dispersive use, direct handling, intermittent Exposure levels: 0.1 – 1 mg/cm 2 /day
If vinyl acetate monomer is used (polymerisa tion step), dermal exposure amounts to 42 – 420 mg/person/day. The upper value is regarded to represent the reasonable worst case situation. For vinyl acetate with the EASE estimate of 1 mg/cm2, an evaporation time of 10 second (T = 30°C) is calculated. For vinyl acetate on the glove s, an assumed temperature of 20°C leads to a similar evaporation time.
Taking into account the content of residual vi nyl acetate monomer of < 3000 ppm in the vinyl acetate (co)polymer, the estimated level of dermal exposure reduces to < 0.0003 - < 0.003 mg/cm 2 /day (formulation step). Considering an exposed area of 420 cm 2 (palms of two hands), dermal exposure amounts to 0.13 – 1.3 mg/person/day. For the assessment of the health risks, the upper value should be taken. On account of the high vapour pressure of vinyl acetate (12 kPa) and the resulting short retenti on time on the skin, lower levels of dermal exposure than the estimated ones are to be excepted.

4.1.1.2.3 Use of formulations and products containing residual monomeric vinyl acetate (scenario 3)
There is no direct use of vinyl acetate monomer . However, exposure may result from the use of formulations and products like paints and pl asters, glues (e.g. for carpets or structural members), and coatings, which are based on vinyl acetate (co)polymers containing small amounts of residual monomer. Formulations and products based on vinyl acetate (co)polymers like adhesives and paints contai n < 2 - 3000 ppm residual vinyl acetate, which normally evaporates when applied by the end user. Due to hydrolysis of the residual monomer, its content might be reduced.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 32 The main uses of polyvinyl acetate and vinyl acet ate copolymers are applications in polymer dispersions. Homopolymer and copolymer disper sions are important binders for indoor and outdoor paints, special coatings, and textile finish ing agents. Dispersions are used for plasters and water-thinable adhesives. Special types are a pplied in wood paints as well as in coatings for paper and cardboard, in adhesives and textile finishing agents (Ullmann, 1998).
Quantitatively less important than polyvinyl acetate dispersions are solid resins which are used as binders in paints for paper, car dboard, wood, leather, certain plastics and in impregnation coatings. Vinyl acetate (co)polymers are an extremely important raw material in the adhesives industry. Copolymerisation of vinyl acetate with other monomers allows specific improvement of certain properties. These copolymers are used in heat-sealable finishes on paper, cardboard and aluminium foil, as a raw material for wash-off adhesives, textile finishing agents and marking inks (Ullmann, 1998).
Inhalation and dermal exposure to traces of re sidual monomer is possibl e during a variety of activities depending on the product in use, e. g. charging, mixing and coating work as well as cleaning work. As a worst case it is assumed th at these works are performed daily during the whole shift.

Inhalation exposure
Workplace measurements
Workplace measurements obtained during the use of vinyl acetate products have been submitted by German Employer’s Accident Liab ility Insurance Association for the period 1990 - 1995 (BGAA 1996).
Table 4.1.1.2.3: Vinyl acetate exposures at different workplaces (BGAA 1996)

Job category / activities Years of measurement Number of samples Range of measurement data [mg/m 3 ] Geometric

mean [mg/m 3 ] 95 th percentile

[mg/m 3 ] Duration and frequency

8-h time weighted average

Wood working industry (hot melting glues) 1990 - 1995 162 - 1 2 -

Coating works (painting) 1990 - 1995 28 - 1 1 -

Air emission of residual vinyl acetate monomer during gluing of a carpet in a closed room with a glue containing 20-30 w/w polymer dispersion has been detected as 2.6 mg/m 3 (0.7 ml/m 3 ) (Hoechst AG, 1993a). Based on the cond itions of exposure (closed room, limited ventilation) this value is regarded to represent a worst case situation.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 33 FIN provided data from silk screen printing (0.18 mg/m 3 ) and paper cardboard coating, paste mixing and coating (6 ± 7.7 mg/m 3 ). Since no further information is available, this data cannot be considered in exposure assessment.

Conclusions

Because of the low residual monomer content in formulations, on the average 3000 ppm, low inhalation exposure levels are to be expected. This is confirmed by the available measurement results. For the area of the application of pr oducts (e.g. adhesives, paints) on the basis of polymeric vinyl acetate 2.6 mg/m 3 (determined during air emission monitoring) should be taken as a worst case for assessing the risk of inhalation exposure.

Dermal exposure
For the handling of various polyvinyl acetate pr oducts in industrial and skilled trade areas it cannot be excluded that gloves are not regularly worn and that immediate dermal contact occurs (Voullaire and Kliemt 1995). Since detailed information on the possible activities are missing, for a rough estimation, dermal exposure is assessed with the EASE model using the category “wide dispersive use“:
Input parameters: wide dispersive use, direct handling, intermittent Exposure level: 1 - 5 mg/cm 2 /day.
Taking into account the content of residual vi nyl acetate monomer of < 2 – 3000 ppm in the different products, the estimated level of dermal exposure reduces to < 0.003 - < 0.015 mg/cm 2 /day. Considering an exposed area of 840 cm 2 (both hands, worst case), dermal exposure amounts to 2.5 – 12.6 mg/person/day. The hi gher value is regarded to represent the reasonable worst case. It is to be assumed, that the content of residual monomer in the dispersions is decreased by chemical reactions of vinyl acetate, e.g. further polymerisation or hydrolysis. In addition, dermal exposure may be lowered by the evaporation of the substances (vapour pressure: 12 kPa).

4.1.1.2.4 Summary
Based on the available information, the expos ure assessment reveals that handling the monomeric substance in the areas of produc tion and polymerisation, the formulation of adhesives as well as the use of formulations, es pecially of adhesives, are the main source for occupational exposure. Direct uses of the s ubstance other than polymerisation are not known. Applications of the manifold products contai ning vinyl acetate in traces as residual monomer, e.g. adhesives, coating materials and paints, are regarded to be of minor relevance.
The relevant inhalation and dermal exposur e levels are given in tables 4.1.1.2.4 A and 4.1.1.2.4 B, respectively.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 34 For the large-scale chemical industry, it is a ssumed that the production and polymerisation of vinyl acetate is mainly performed in closed sy stems with high levels of protection. Exposure occurs if the closed systems are breached for certain activities e. g. filling, cleaning and sampling in the area of manufacturing and polymerising of vinyl acetate monomer (scenario 1). Dermal exposure is assessed using the EA SE model (scenario 1). In addition, the high vapour pressure of vinyl acetate is taken into account as an exposure reducing effect.
According to information provided by industry, there is normally no use of vinyl acetate monomer in formulating facilities and exposur e is limited to the use of vinyl acetate (co)polymers containing < 2 – 3000 ppm resi dual monomer. However, some adhesive producing facilities use vinyl acetate monomer for (co)polymerisation and perform the formulation subsequently. Therefore, this e xposure scenario comprises the polymerisation step (vinyl acetate monomer) and the formula tion step (use of residual vinyl acetate in (co)polymers). Generally, in formulating facilities different levels of protection are realised. In part, processes like filling and mixing are performed in open systems.

Measurement results are available from formul ating adhesives only (scenario 2). This fact might indicate, that exposure to vinyl acetate at other formulating processes. e.g. of paints, is lower. The available exposure levels reveal that exposure of 47 mg/m3 vinyl acetate occurs. On the background of the information that nor mally only vinyl acetate (co)polymer is used, these high levels are non-plausible. At present it is assumed, that the high levels relate to the use of vinyl acetate monomer (polymerisation st ep). If no monomer is handled and a company uses only vinyl acetate (co)polymers (formula tion step), exposure is expected to be considerably lower.
The widespread industrial and skilled-trade app lications of polymeric dispersions and solid resins containing residual vinyl acetate monomer (< 2 – 3000 ppm) comprise uses in paints, lacquers, adhesives, plasters and coating materials (see chapter 4.1.1.2.3). In scenario 3 a worst case situation is described assuming 3000 ppm residual monomer and daily exposure during the whole shift.R059_0805_env_hhDraft of 29.05.2008CAS No.: 108-05-435Table 4.1.1.2.4 A: Summary of inhalation exposure data of vinylacetate which are relevant for occupational risk assessmentInhalation exposureArea of production anduseForm ofexposureActivityDuration[hs/day]Frequency[days/year]Shift average[mg/m3]MethodShort-termexposure[mg/m3]Method1.Production andpolymerisation in thechemical industryvapour(liquid)filling, sampling,cleaning, repair,maintenance8 h / day daily3.0(reasonable worstcase)95thpercentile- -2.Manufacturing offormulations andproducts (e.g.adhesive production)vapour(liquid)filling, sampling,cleaning, repair,maintenance8 h / day(assumed)daily14.6(reasonable worstcase)90thpercentile47(30 min, use ofvinyl acetatemonomer)measurement value3.Use of formulationsand productscontaining residualvinyl acetate monomer(< 2 – 3000 ppm)vapour(liquid)different activities,e.g. coating,painting8 h / daily(assumed)daily2.6(worst case)laboratoryexperiment,worst caseconditions- -R059_0805_env_hhDraft of 29.05.2008CAS No.: 108-05-436Table 4.1.1.2.4 B: Summary of dermal exposure data of vinyl acetate which are relevant for occupational risk assessment (reasonable worst case)Dermal exposureArea of production and useForm ofexposureActivityFrequency[days/year]Contactlevel(1)Level of exposure[mg/cm2/day]Exposedarea [cm2]Shift average[mg/p/day]Method(use of PPE)1.Production andpolymerisation in thechemical industryliquid filling, sampling,cleaning, repair,maintenancedaily intermittent 0.1(2)420(palms ofhands)42(2)EASE, exp.judgement(suitablegloves)2.Manufacturing offormulations and products(e.g. adhesive production)a) polymerisation step(vinyl acetate monomer)b) formulation step (vinylacetate (co)polymer)liquid filling, sampling,cleaning, repair,maintenancedaily intermittent 1(2)1(3)420(palms ofhands)420(palms ofhands)420(2)(a)1.3(3)(b)EASE,(withoutgloves)EASE,(withoutgloves)3.Use of formulations andproducts containingresidual vinyl acetatemonomer(< 2 – 3000 ppm)liquid differentactivities, e.g.coating, paintingdaily intermittent 5(3)840(hands)12.6(3)EASE(withoutgloves)(1)Contact level according to the EASE model(2)The EASE estimate is largely reduced because of the short duration time of dermal exposure. The retention time of pure vinyl acetate is calculated to 1 second for0.1 mg/cm2 and to 10 seconds for 1 mg/cm2 (order of magnitude) independent on the use of gloves (non-occlusive exposure).(3)Worst case estimation assuming 3000 ppm residual monomer. Due to the high vapour pressure of the substance shortened retentiontimes on the skin are to be expectedleading to considerable lower dermal exposure levels than estimated with the EASE model. For vinyl acetate in mixture the retention time cannot be calculatedbecause of the complex composition of the mixtures and their specific drying behaviour.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 37 4.1.1.3 Consumer exposure
According to the Swedish product register, products containing vinyl acetate are used by consumers in Sweden. Such products are e.g. mo isture barrier paints and other paints and lacquers/varnishes on a solvent basis, adhe sives, glues, dispersion adhesives, hotmelt adhesives and sealing compounds. The consumer products are offered in wholesale and retail trade, e.g. in repair shops for motor vehicles and motorcycles as well as for personal and household goods (as per February 1995).
In the Norwegian product register, 15 products for use in the consumer field have been listed in which vinyl acetate is used as a component of paints for the exterior and interior application to houses (as per 16 December 1994). No information is available for the amount of vinyl acetate in the formulations.
In the Federal Republic of Germany, polyvinyl acetate is known to be used e.g. as a component of adhesives (vinyl acetate polymer content up to 36%), car polishing products (primers, polyvinyl acetate copolymer content up to 1.5%), hair care products (hair setting lotions, vinyl acetate copolymer content up to 3% , hair care products) and in plastics for toys and those coming into contact with foods. These products contain traces of vinyl acetate as a residual monomer; in adhesives (e.g. film a nd surface adhesives), the residual monomer content is 0.1 - 0.2% (voluntary reporting by the manufacturers/distributors etc. to the BgVV (as per 01.04.1996); Umbach, 1995; Ellenhorn and Barceloux, 1988). This content would be similar to 1000 - 2000 ppm.
In case reports from the Swiss Toxicological In formation Centre, polyvinyl acetate is stated as a component of paints and lacquers/varnishes (binding materials) for households (Velvart, 1993). According to the data provided by the ma nufacturers, the concentration of polyvinyl acetate is up to 13%, and that of vinyl acetat e as a residual monomer up to a maximum of 0.3% in the (co)polymer. In water-based pain ts residual vinyl acetate monomer hydrolyses rapidly.
According to information provided by the industr y, poly vinyl acetate is used in printing inks. The maximum polymer concentration is 60%, the maximum concentration of the residual monomer is 0.2%; this results in a maximum content of vinyl acetate monomer of 0.12%.

Inhalation exposure

Measured exposure data from paints At present, „solvent- and emission-free“ paints and plasters are available based on binders and additives with a content of volatile orga nic components (VOC; sum of vinyl acetate, acetaldehyde, and formaldehyde) below 100 ppm (Zeh et al., 1994).

In an exposure study monitoring volatile compone nts of polyvinyl acetate (PVA) based paints all fixed-station area air samples collected during application and drying of the painting process and analyzed for vinyl acetate showed concentrations below the analytical limit of detection (Kominsky and Freyberg 1992). The av erage environmental limit for detection with regard to fixed-station area air samples (measurement during application and drying up to 6R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 38 hours after application) was 10 ppb (= 36 μg /m3). The average environmental limit of detection for personal breathing zone concentrations during paint application was 220 ppb.
The content of vinyl acetate monomers (VAM) in the samples of paint used during the study were <1 to 8.2 ppm (Kominsky and Freyber g, 1992). Shortly after production of paints relatively high amounts of residual monomers of ≈ 3200 ppm can be found. In the process of incorporating the resin into the paint product, th e residual VAM content of the resin is lost or converted to hydrolysis products (acetic acid and acetaldehyde). This conclusion is supported by the results of the air monitoring for vinyl acetate during and after paint application.
Surfaces coated with products containing polymer dispersions of vinyl acetate are generally free of vinyl acetate before dryi ng since due to the difference in vapour pressure vinyl acetate evaporates more quickly than water (Wack er-Chemie, 1993). In addition, vinyl acetate hydrolyses at pH 8 to 9 (usual pH in paints) w ith a half-life of less th an 4 days. With respect to potential vinyl acetate evaporation from glue s of building material, due to the high vapour pressure of vinyl acetate building material might be free of vinyl acetate after a short time and not lead to a long-term vinyl acetate burden in the rooms (Wacker-Chemie, 1993).
From this point of view it can be expected that vinyl acetate emission is very low from paints. In an experimental study, where paints have b een spiked with vinal acetate, Zeh et al. (1994, 2000) have evaluated VOC emissions from pa ints and, as a constituent of VOC’s, vinyl acetate. The experiments showed excellent correlation between measured and modelled data. With a paint spiked with 1200 ppm, room air le vels were found of 10 mg/m3. Extrapolating these findings to paints containig concen trations in the range < 10 ppm, the room concentrations of vinyl acetate af ter use of paints shound not exceed levels in the range of 0.1 mg/m3.

Adhesives for carpets and other film and surface adhesives Polyvinyl acetate is used as a component of f ilm and surface adhesives, e.g. for carpets and floor sealings; 0.1 - 0.3% of vinyl acetate are c ontained in the products as residual monomer.
The monitored air emission of vinyl acetate duri ng gluing of a carpet with a VAM containing glue in a closed room has been detected at 2.6 mg/m 3 (glue formulation: 20-35% dispersion; the maximum VAM content of the dispersion is typically 0.1-0.3%) (Hoechst, 1993).

This information can be used to estimate an acute exposure to the person who is gluing the carpet (normally workplace exposure). From ot her studies (Zeh, 1994, 2000) it is known that vinyl acetate concentrations will decline quick ly and remaining long-term exposure may be low. There is no further information on room ai r levels although gluing carpets may serve as a considerable source of exposure to vinyl acetate.

Emission of vinyl acetate from carpets
Vinyl acetate had been found after 16 hours of equ ilibration in a concentration of less than 2 μ g/m 3 (limit of detection) in air over three different carpets (two with and one without a finish containing up to 2000 ppm vinyl acetate; carpet size 0.2 m 2 , test chamber size 0.5 m 3 , air exchange rate 0.5 h -1 (Deutsches Teppichforschungsinstitut e.V., 1992)).
In an US study the air emissions of four ne w carpets (typically installed in residences, schools, and offices; the carpet samples were collected at the manufacturers’ millsR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 39 immediately following production) were meas ured in room air under simulated indoor conditions in a 20 m 3 environmental test chamber over a period of one week following installation. After 3 hours the initial con centration amounted about 290 ppb (1.04 mg/m 3 ) and after 168 hours about 10 ppb (0.036 mg/m 3 ). The emission rate was estimated to be 853 μ g/m 2 per hour after 24 hours and 103 μ g/m 2 per hour after 168 hours. Altogether the carpets emitted 85 mg/m 2 of vinyl acetate over the peri od of 168 hours (Hodgson et al., 1992a, 1992b). The room air ventilation rate was 1 h -1

. The results of these studies obviously show, that the emission of vinyl acetate varies greatly.
For risk assessment therefore the highest amounts that have been measured should be taken into consideration. As a realistic worst case estim ate, the concentrations of vinyl acetate from carpet emissions would then amount to about 1000 μg/m3 (~ 300 ppb). For chronic exposure, the concentration measured by Hodgson et al . (1992a, 1992b) after 168 h equilibrium of 36 μg/m3 ( ≈ 10 ppb) should be taken.

Chronic exposure results in ≈ 0.2 μg/kg/h for women (activity level: resting) and ≈ 0.4 μg/kg/h for men (activity level: resting) accounting for 4.6 and 9.2 μg/kg bw per day, respectively. For 3 year-old children, the result of estimation of chronic exposure by inhalation is 0.78 μg/kg/h (18 μg/kg bw per day).
For calculating exposures the following data have been used (AIHC, 1994; AUH, 1995):

3-year-old children Adult (women) Adult (men) Body weight (TGD defaults) 11 kg 60 kg 70 kg Breathing volume (resting) 0.24 m3/h 5 0.3 m3/h 0.7 m3/h Time of residential stay 23 h 23 h 23 h
The inhalation exposure (Exp inh ) has been calculated by the equation

B W r c Exp inh air inh *

= , where c air is the room air concentration obtained by measurements and r inh the breathing volume (see table).

Exposure to car polishing products (primers ) In car polishing products (primers), polyvinyl acet ate copolymer is used in a concentration up to 1.5%. The residual monomer content of vinyl acetate is very low so that the consumer exposure to vinyl acetate in this field of use may be neglected.

Exposure from printing inks

5 conservative unfavorable assumption for breathing rates considering chronic exposure over whole day ( Finley, et al. 1994)R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 40 The use of printing inks containing vinyl acetat e may lead to an exposure of consumers. Printing inks are used for example in computer ink-printers. For this purpose, the ink-solvents must volatilize very quickly. The content of a cartridge is 50 ml, the vinyl acetate residual monomer content is then 0.06 g. If the cartridge is used for 1 month, the daily release of ink will amount to 0.002 g. The liberation of this amount in a room of 40 m3 results in a concentration of 0.05 mg/m3.

Dermal exposure Exposure to hair setting lotions The Scientific Committee (Scientific Committ ee, 1994; Colipa 1989) has stated a consumer exposure to hair setting lotion up to 1 g/day. Hair setting lotions contain up to 3% vinyl acetate copolymer which corresponds to a daily consumer exposure of 30 mg vinyl acetate copolymer. Assuming a residual monomer conten t of 0.2% vinyl acetate, the consumer exposure to vinyl acetate will be 60 μg vinyl acetate daily or 1 μg/kg bw and day.

Oral exposure Exposure to plastics coming into contact with food etc.

Substances that will come in contact with food as monomers for the manufacture of plastics are regulated under the "Regulations to am end the Regulations on Specific Commodities under the Foods Act, 1994". In this regulation, a maximum value of 12 mg/kg migrating from articles is allowed. This means, that an amount of 12 mg of the vinyl acetate residual monomer may migrate from one kg of food. Taking into consideration, that the real migration rate of vinyl acetate from plastic material is not known, and according to the proposed classification of vinyl acetate migration from articles must be held as low as possible.
A tolerable daily intake (TDI) value of 0.2 mg/kg bw has been established 6

.

Conclusion

6 A tolerable daily intake (TDI) value of 0.2 mg /kg bw has been established. This rather high value was derived by taking the NOAEL and applica tion of safety factors. The amount of the daily intake from migration can be roughly estimated assuming the following parameters: A can with a weight of 500 g containing 0.1% of vinyl acetate residual monomer contains a volume of one liter liquid. Assuming that 0.1% of the residual monomer will migrate every day, then an amount of 0.5 mg will migrate per day, which would result in an oral exposure of about 0.01 mg/kg bw if one person will drink the total content of the can. Therefore, it seems unlikely that the regulatory limits will be reached.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 41 Following the exposure assessment there is no di rect exposure of the consumer to vinyl acetate besides of the release of monomers from polymers. Overall exposure of consumers to vinyl acetate results mainly from inhalation due to emissions from carpets, paints and adhesives. However, there is a lack of suffi cient data on other uses. For comparison with acute effects, the estimate for short-term exposur e from carpets will be used (concentrations of 1 mg/m3). With regard to chronic effects, the concentration of 0.036 mg/m3 for long-term exposure will be used resulting in an exposure of 9.2 μg/kg bw/d for men, 4.6 μg/kg bw/d for women, and 18 μg/kg bw/d for children. For the risk characterisation a value of about 10 μg/kg bw/d for adults will be used.
The dermal exposure to vinyl acetate is estimated to be about 1 μg/kg bw/d.
The sum of all types of exposure resulting fr om residual monomeric vinyl acetate (reasonable worst case) is estimated to be in the range of 5 to about 20 μg/kg bw/d.

4.1.1.4 Indirect exposure via the environment
According to Appendix VII of chapter 2 of the TGD, the indirect exposure to humans via the environment, i.e. through food, drinking water and air is estimated.
As a worst case scenario, the maximum intake due to exposure in the vicinity of a vinyl acetate production facility is calculated (site 26). This is compared to an average intake due to exposure via the regional background concentration.

The resulting total daily dose is: DOSE tot_local = 36 μ g / kg bw d

DOSE tot_regional = 2.47 E-03 μg / kg bw d

The calculated total doses comprise the following routes:

Percent of total dose Route local regional Drinking water 1.26 9.64
Fish 2.97E-05 0.44
Stem 0.36 0.33
Root 0.24 0.37
Meat 2.04E-04 2.41E-04
Milk 3.80E-03 4.50E-03
Air 98.13 89.22

The main route of indirect exposure of both s cenarios is the intake via inhalation of air.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 42 4.1.2 Effects assessment: Hazard identifica tion and Dose (concentration) - response (effect) assessment

4.1.2.1 Toxico-kinetics, metabolism and distribution
Vinyl acetate is hydrolysed by carboxylesterase s to acetic acid and acetaldehyde which is subsequently oxidized to acetic acid by aldehyde dehydrogenases. Acetate enters the citric cycle in an activated form as acetyl coenzy me A. Vinyl acetate metabolism not only takes place in the liver but also in several tissues wh ich might be of relevance for the toxicological effects elicited by vinyl acetate.
The main pathway for the metabolism of vinyl acetate is shown in Fig. 1.

Fig. 1:
Biotransformation Pathways for Vinyl Acetate
(Modified from Bogdanffy et al., 1998) A cetyl-CoA CE A ldDH

ACS A cetaldehyde Acetic Acid

CE AldDH ACS +R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 43 Animal data – in vivo

Inhalative exposure Four CD rats (Sprague-Dawley-derived), 2 ma les and 2 females, were exposed nose only to an atmosphere of nominal 750 ppm of 14 C-vinyl acetate (labelled at the vinyl moiety) for 6 h (2.68 mg/l x 0.8 l/min/kg x 360 min ≈ 772 mg/kg bw). The authors presented the results (radioactivity in urine, faeces, expired air, cag e washing and carcasses) as percentage of the total radioactivity recovered b ecause the precise amount of ( 14 C)-vinyl acetate given to the animals was not known. The tables and appendi ces were not available to the rapporteur, therefore data are given as described by the authors. During a 96 h period the mean proportions of the recovered (not the administ ered!) radioactivity found in urine, faeces and expired air were 4.8, 3.6, and 74.6%, respec tively. The major portion of radioactivity was eliminated in the first 24 h. A mean of 16.4% of the total recovered radioactivity was present in the carcass after 96 h. In case of nose-onl y inhalation of 750 ppm (772 mg/kg bw) about 83% of the recovered radioactivity were found in the expired air (as CO 2 ), urine and faeces. Based on the fact, that the percentages of radi oactivity presented were based on the recovered amount of radioactivity and taking into consider ation that presystemic metabolism in the nasal cavity occurs, no conclusions about the amounts of systemically available vinyl acetate can be drawn from this investigation. For investigati on of tissue distribution (number of animals not available) radioactivity was investigated immediately, 1, 6 and 72 h after a 6 h exposure to a nominal dose of 750 ppm 14 C-vinyl acetate. Immediately after exposure, the highest mean concentrations of radioactivity were found in harderian gland, ileum, submaxillary salivary gland and the contents of the gastrointestinal tract. Radioactivity was widely distributed with relatively high levels present in liver, kidneys, lung, brain, stomach, colon and ovaries. 1, 6 and 72 h after exposure, the pattern of dist ribution was approximately the same although concentrations had declined. 72 h after exposur e, the harderian gland, adrenal gland and ovaries contained the highest mean levels of radioactivity (Strong et al., 1980; the appendices and tables of the study were not available to the rapporteur).
Two male Wistar Rats exposed to vinyl acetate (stabilised with 0.01% hydroquinone) concentrations varying between 200 and 2000 ppm in closed chambers with an exposure time of 1.4 h or less demonstrated dose dependent e limination kinetics. The authors concluded that the metabolic pathways became saturated when vinyl acetate exposure levels exceeded 650 ppm (2320 mg/m 3 ) (Simon et al., 1985a).
Vinyl acetate deposition was measured in the isolated upper respiratory tract (URT) of anaesthetised adult male CrlCD:BR rats at exposure concentrations ranging from 73 to 2190 ppm during 1h inhalation under unidirectional flow conditions (flow rate 100 ml/min) (Plowchalk et al., 1997). The UR T was isolated by inserting a polyethylene tube into the trachea to the level of the nasopharynx of sodi um pentobarbital anaesthetised (70 mg/kg bw, ip) rats (250 to 350 g). A separate cannula was in serted into the trachea, toward the lungs, to maintain a patent airway. A valve system allowed alternative switching between two impingers to enable the continuous collection of expired air. Each animal was then placed into a holder in a supine position and the nose was inserted with Batelle-style nose-only restrainers into an exposure chamber. Chamber atmosphere (C in , 73 to 2190 ppm vinyl acetate in nitrogen, 34 °C, humidity 88%) was drawn through the URT under constant velocity (nominal 100 ml/min) and unidirectional flow cond itions. The air exiting the nasal cavity (C exp ) was trapped in an impinger. Preliminary experi ments showed that approximately 8 min ofR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 44 exposure was required for vinyl acet ate to achieve a steady state in nasal tissues. After 8 min of equilibration, impinger samples were collect ed, approximately every 4 min, for up to 40 min and analysed for vinyl acetate and acet aldehyde by gas chromatography. Fractional deposition (equivalent to extraction) of vi nyl acetate in the URT was calculated as (C in - C exp )/C in . Fractional deposition of vinyl acetate fr om the nasal cavity was non-linear with reference to exposure concentration and range d from 36 to 94%, with greatest uptake at lowest vinyl acetate concentrations. While the exposure concentration was increased from 76 to 550 ppm, uptake decreased progressively to a bout 40% and remained at this level up to approximately 2000 ppm. When simulations were performed without carboxylesterase activity in nasal mucosa, it could be calcula ted, that vinyl acetat e deposition due to bloodflow extraction is minimal and accounts for less that 15 % of total deposition (Plowchalk et al., 1997; Bogdanffy et al, Bericht 1998). Acetal dehyde was found in expired air at all vinyl acetate exposure concentrations. With increasing the vinyl acetate exposure, concentration of acetaldehyde in expired air increased. At vi nyl acetate exposure of approximately 1000 ppm the concentration of acetaldehyde in the expired air was 277 ppm (499 mg/m 3 ). To study the effect of carboxylesterase inhibition on vinyl acetat e deposition, rats (n = 10) were pre-treated for 3 days with one ip injection per da y (0.2 ml/100g bw) of a 5% BNPP (bis(pnitrophenyl)phosphate, an inhibitor of carboxylestera se) suspension in saline. Pre-treatment of rats with BNPP significantly decreased fracti onal deposition of vinyl acetate. At exposure concentrations ranging from 76 to 663 ppm , BNPP pre-treatment reduced fractional deposition by at least 55% compared to that seen in naive rats. The appearance of acetaldehyde in the expired air and the inhibiti on of its formation by the inhibitor BNPP are indicative for a carboxylesterase-mediated metabolism of vinyl acetate.

Oral exposure
Rats were administered oral doses of 14 C-vinyl acetate (labelled at th e vinyl moiety, 1 ml of a 10000 ppm (v/v) aqueous solution, overall dose level 297 mg/kg bw) by gastric intubation. The dosing regimen was 6 times 1 hour apart. During the dosing regime and subsequent 96 h collection period, a mean of 64. 4% of the administered radioactivity was excreted (1.4% in faeces, 1.8% in urine and 61.2% in exhaled air). In addition a mean of 5.4% was found in the carcass at 96 h. The major portion of the urinary radioactivity was excreted within the first 24 h. Most of the radioactivity eliminated by the expired air was recovered during the 6 h dosing regime and the first 6 h after dosing. This por tion of radioactivity was recovered from the traps designed for collecting carbon dioxide. The authors of the study suppose, that the unaccounted 30.1% of the dose were most likely lo st in the expired air, which escaped from the metabolism cages when the animals were removed for dosing. There was a wide tissue distribution of radioactivity following administration of 14 C-vinyl acetate by the oral route. One hour after the sixth dose the highest mean c oncentrations of radioactivity were found in the harderian gland and the submaxillary salivar y gland. High levels were also found in the liver, kidney, stomach, ileum, colon and gastrointe stinal tract contents. Low concentrations of radioactivity were found in fat. Attempts ha ve been undertaken to determine vinyl acetate metabolites in urine and faeces. No radiolab elled carbonates or bicarbonates were found in urine or feces. Thin layer chromatography of urine indicated that there was one major radioactive fraction and several minor fracti ons (Strong et al., 1980). Exhaled radioactivity was entirely present as 14 C carbon dioxide. Therefore it can be concluded, that 63 % of orally applied 14 C vinyl acetate is excreted as metabolites.
A single oral dose of nominal 1.17 mg of 14 C-vinyl acetate (labelled at the vinyl moiety) was orally administered to albino mice of the CDI strain (3 male, 3 female). Animals were takenR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 45 for analysis 1, 6 and 72 h after administrati on. Whole-body autoradiograms indicated a wide distribution of radioactivity. High concentrati ons were observed in harderian and salivary glands, gastrointestinal mucosa, liver and brown fat (Strong et al., 1980).

Solutions of 0.9 % saline containing various con centrations of vinyl acetate were placed in the mouth of anesthetized male F344 rats for 10 min and then analyzed for acetaldehyde by HPLC (Morris et al., 2002). Acetaldehyde was de tected in these solutions providing evidence that metabolism of vinyl acetate occurs in vivo in oral tissues.

Dermal exposure There are no studies on absorption, metabolism, distribution and excr etion of vinyl acetate after dermal exposure. A study has been undert aken to determine acute dermal toxicity (Mellon Institute, 1969), see also section “Acute toxicity”. In brief, all animals died after occlusive application of 16 ml vinyl acetate per kg bw on to the sk in of rabbits. After occlusive application of 4 ml/kg, gross pathol ogy revealed congestion of the lungs and liver, mottled spleen and kidney and prominent liver aci ni. The results indicated that vinyl acetate might be systemically bioavailable after dermal application.

Other routes Injection of vinyl acetate (i.p.) to female Ch ester-Beatty rats (0.8 ml/kg bw) resulted in a decrease of hepatic glutathione level to 77% of the normal value 30 min after application (Boyland and Chasseaud, 1970). Similar decreas es of hepatic non-protein sulfhydryls were reported after i.p. vinyl acetate injection to mice (300 mg/kg bw), Wistar rats (300 or 450 mg/kg bw) and guinea pigs (500 mg/kg bw) (Hol ub and Tarkowski, 1982). It is assumed that these findings may indicate conj ugation with glutathione. However due to the limited data the relevance of this pathway cannot be assessed.

Human data – in vivo

Inhalative exposure To provide validation data for the application of the PBPK model developed by Bogdanffy et al. (1999b; see also section PBPK modelling) in humans, controlled human exposures to inhaled vinyl acetate were conducted (Hinder liter et al., 2005). Air was sampled by a probe inserted into the nasopharyngeal cavity of five volunteers (two women, three men). Volunteers were instructed to inhale and e xhale through the nose. Sampling was carried out during exposure to labelled 13 C1, 13 C2-vinyl acetate during resting and light exercise at three exposure levels (1, 5 and 10 ppm nominally). Both, labelled vinyl acetate and the major metabolite acetaldehyde from the nasopharyngeal region were sampled at a calibrated flow rate of 12 l/h and analysed in real time utilising ion trap mass spectrometry (MS/MS). Measurements were taken every 0.8 sec in an exposure period of 2 to 5 min resulting in data during all phases of the breathing. The rate of sampling was rapid enough to capture much of the behaviour of vinyl acetate in the human na sal cavity including inhalation and exhalation. However, the sampling was not frequent enough to accurately capture the peak concentrationR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 46 in every breath. The method is free of in terference from endogenous compounds and its detection limit is in the single digit ppb level. An acoustic rhinometry system was used to measure the cross-sectional area and volume of the nasal cavity. The complete set of human exposures resulted in a data set with over 22000 data points of vinyl acetate and acetaldehyde.

Oral exposure

There are no toxicokinetic data on human oral vinyl acetate exposure.

Dermal exposure There are no toxicokinetic data on human dermal vinyl acetate exposure.

In vitro data (both animals and humans)

Carboxylesterase activity
Carboxyl esterase activity in the nose
Vinyl acetate hydrolysis has been studied in v itro in the nasal tissues of F344 rats and B6C3F1 mice. Homogenates of nasal respiratory and olfactory mucosa, adjusted to pH 7.4, were incubated with vinyl acetat e at 37°C for 10 min (respiratory mucosa) or 2 min (olfactory mucosa). It was shown that nasal esterases catalyse formation of acetaldehyde and acetic acid with high efficiency. V max values for rat and mouse respir atory tissue ranged from 22 to 46 μmoles/min/mg protein (22 to 24 for rat; 30 to 46 for mouse) which is in the same range as the data obtained in rat liver microsomes ( 23 μmoles/min/mg protein, Simon et al., 1985a). V max for rat and mouse olfactory tissue ranged fr om 89 to 165 μmoles/min/mg protein (88 to 92 for rat, 95 to 165 for mouse). K m values obtained for rat and mouse nasal tissues ranged from 0.30 to 1.07 mM and were similar among olfactory and respiratory epithelium (Bogdanffy and Taylor, 1993). The enzyme ki netic data for carboxylesterase mediated hydrolysis of vinyl acetate do not account for the species differences in susceptibility to the carcinogenic effects of vinyl acetate. Values are listed in Table 1.
Carboxylesterase activities have also been investig ated in nasal (respiratory, olfactory) tissue from different species using p-nitrophe nolbutyrate (Bogdanffy et al., 1987) or methylmethacrylate (Mainwaring et al., 2001) as substrates for carboxylesterase (see Table 2). Higher carboxylesterase activities could be determ ined in olfactory tissue of rats and mice compared to respiratory tissue. However, it is difficult to draw firm conclusions concerning carboxylesterase activities in nasal tissues of humans and rodents, because vmax values in human samples were obtained when analyzing just one substrate concentration. In the case of human olfactory tissue, only S9, but not microsom es have been analyzed (Mainwaring et al., 2001) which makes species comparison difficult.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 47 Since the nasal cavity epithelium is composed of a heterogeneous cell population, measurement of xenobiotic metabolizing enzy mes using homogenates could yield artificial results. Therefore, an in vitro gas uptake techni que has been established in order to enable more accurate measurement of kinetic consta nts (Bogdanffy et al., 1998). By applying this method, whole rat turbinates from CrlCD:BR rats covered with either respiratory or olfactory epithelium or sections of human nasal tissue (m iddle turbinate or dorsal meatus) were placed in a sealed scintillation vial. Vinyl acetate va pour was injected into the headspace over the tissue and its loss from the vial headspace and the appearance of acetaldehyde were determined and modeled using a distribut ed parameter model that reflects tissue histochemistry. In this model the individual co mpartments are said to represent epithelial cells, basal cells, or submucosal tissue in the respiratory and olfactory mucosa. Rat turbinate surface areas were estimated using a three-di mensional, anatomically “accurate” computer model of the nasal passages from one F344 rat. Human turbinate surface areas were estimated from the tissue samples. Vapour is transporte d to the air: tissue interface by diffusion. The diffusivity of the vapour in the tissue is appr oximated by its diffusivity in water. The vapour diffusivity in all the tissue subcompartments is assumed to be equal. Metabolic activity is assumed to be located in the tissue compartments according the observations from enzyme histochemical and immunohistochemical studies . The kinetic parameter estimates were compared to those derived from homogena te experiments using two normalization procedures. When the normalization took into account tissue architecture (epithelial cell volume vs. tissue wet weight), a good agreemen t between homogenization technique and gas uptake technique could be observed in animal tissues. No clear conclusions on species differences could be drawn from these inve stigations, because dependent on the scaling technique, different results we re obtained for respiratory and olfactory carboxylesterase activities in rats and humans. An overview about carboxyl esterase activities in different rat and human tissues is given in Table 1. Major dr awbacks of this technique were that mucosal and blood flow and cofactor lo ss were not taken into account by the in vitro gas uptake methodology and that only one rat has been used to create a computer model.

Carboxyl esterase activity in the oral cavity
Vinyl acetate hydrolysis has been investigated in homogenates from oral cavity mucosa which has been obtained from different regions of th e oral cavity of male F344 rats and male BDF mice. Homogenates were incubated for 30 min with various concentrations (0.05 – 10 mM) of vinyl acetate and the production of acetaldehyde was quantified by HPLC. All tissue regions possessed vinyl acetate hydrolysis activity. In both species thy hydrolysis activity was greatest in the the dorsal interior regions. Activ ity in the other oral regions was 2-15-fold lower (Morris et al., 2002). Values are given in table 1.

Carboxyl esterase activity in the skin
Carboxyl esterase activities have been determined using different ester substrates (but not vinyl acetate itself) in rat and human skin micr osomes but also in viable skin using flowthrough diffusion cells. Clark et al. (1993) investigated enzyme mediated hydrolysis of fluazifop butyl in human and rat skin post- mitochondrial fraction (with and without the esterase inhibitor BNPP). McCracken et al. (1993) investigated hydrolysis of four different ester substrates in rat skin microsomes and cy tosol. Lobmeier et al. (1996) investigated theR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 48 hydrolysis of different 4-hydroxybenzoic acid es ters in homogenates from different human skin compartments. Frederick et al. (1992) i nvestigated the enzyme-mediated hydrolysis of ethylacetate in rat skin homogenates in comparison to other tissues. It could be demonstrated that rat and human skin both possess carboxyl esterase activities. Results are presented in Table 2. From the investigations by Frederic k et al. (1992) it can be demonstrated, that carboxyl esterase activity in skin homogenate wa s lower compared to lung or liver, but higher compared to blood.

Carboxyl esterase activity in the blood, liver and lung
Vinyl acetate was rapidly degraded in the pres ence of human plasma and whole blood. Half lives for the breakdown of vinyl acetate, usi ng initial concentrations of 30-130 ppm (0.33- 1.41 mM) were approximately 150 sec (2.5 min) with plasma and 210 sec (3.5 min) with whole blood (0.1 M phosphate buffer, pH 7.4, at 37o C). The reaction was shown to be an enzyme-mediated hydrolysis, which was charact erised by a stoichiometric formation of acetaldehyde (Strong et al., 1980).
The enzyme-mediated hydrolysis of vinyl acetate has been studied in vitro with microsomes from rat liver and lung, rat and human plas ma and three different purified esterases (acetylcholine esterase, butyrylcholine esterase and carboxyl esterase). The incubation was carried out at 37°C and pH 8.0. Concentrations of vinyl acetate varied between 1.2 mM and 30 mM in the experiments designed for determination of K m

and V max . Kinetic data show that microsomes (rat liver: V max = 23 μ mol/min/mg protein, rat lung: V max = 6 μ mol/min/mg protein) as well as purified carboxyl esterase (f rom porcine liver) are capable to form acetic acid from vinyl acetate (V max = 238 μ mol/min/mg protein), enzyme activity in rat plasma (V max = 0.6 μ mol/min/mg protein) and human plasma (V max = 0.7 μ mol/min/mg protein) is lower (Simon et al., 1985a).
Degradation of 200 μM vinyl acet ate from in vitro systems c ontaining 1 ml blood or 0.5 ml plasma, or 0.5 ml red blood cells from rats or volunteers, diluted in 0.1 M sodium phosphate buffer pH 7.4, was measured at 37°C. Vinyl acetate disappeared with a half-life of 4.1 min in human blood, and below 1 min in rat blood. In rat plasma vinyl acetate was hydrolysed with a half life of 1.2 min. Preincubation of rat plasma with BNPP lowered the rate of disappearance, suggesting that the reaction was catalysed by carboxylesterases (Fedtke and Wiegand, 1990).
Frederick et al. (1992) compared ethyl acr ylate hydrolysis in tissue homogenates from different rat tissues. Results are presented in Table 2: Carboxylesterase activities (based on substrates other than vinylacetate).R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 49 Table 1: summary of vinyl acetate hydroxylase activities (carboxyl esterase activities) in human and animal tissues

Tissue K m V max Literature
rat respiratory tissue (determined in homogenates from respiratory mucosa) 0.43 mM in males 0.30 (0.34)* mM in females 22.03 [μmol/mg prot/min] in males 23.86 (25.14)* [μmol/mg prot/min] in females Bogdanffy and Taylor, 1993

mouse respiratory (determined in homogenates from respiratory mucosa) 0.42 mM in males 0.76 (0.93)* mM in females 29.6 [μmol/mg prot/min] in males 46.3 (51.78)* [μmol/mg prot/min] in females Bogdanffy and Taylor, 1993

rat respiratory tissue (determined in homogenates from respiratory mucosa, scaled to whole tissue based on wet weight) 0.037 mg/ml 35.7 mg/h Bogdanffy et al., 1998

rat respiratory tissue (determined in homogenates from respiratory mucosa, scaled to whole tissue based on epithelial volume) 0.037 mg/ml 64.9 mg/h Bogdanffy et al., 1998

rat respiratory tissue (determined by the gas uptake technique, scaled to whole tissue based on wet weight) 0.04 mg/ml 10.8 mg/h Bogdanffy et al., 1998

rat respiratory tissue (determined by the gas uptake technique, scaled to whole tissue based on epithelial volume) 0.04 mg/ml 63.0 mg/h Bogdanffy et al., 1998

Human respiratory tissue (determined by the gas uptake technique, scaled to whole tissue based on epithelial volume) 0.05 mg/l 441 mg/h Bogdanffy et al., 1998

Human respiratory tissue (determined by the gas uptake technique, activity per specimen (middle turbinate) 0.05 1.5 mg/h Bogdanffy et al., 1998

Human respiratory tissue (determined by the gas uptake technique, based on epithelial cell volume) 0.05 0.57 mg/h/mm 3 Bogdanffy et al., 1998R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 50 Tissue K m V max Literature
rat olfactory (determined in homogenates from respiratory mucosa) 0.33 (0.55)* mM in males 0.2 (0.51)* mM in females 88.8 (113.5)* ([μmol/mg prot/min] in males 91.52 (135.52)* ([μmol/mg prot/min] in females Bogdanffy and Taylor, 1993

mouse olfactory (determined in homogenates from respiratory mucosa) 0.52 (1.07)* mM in males 0.31 (0.41)* mM in females 164.6 (253.8)* [μmol/mg prot/min] in males 95.5 (107.56)* [μmol/mg prot/min] in females Bogdanffy and Taylor, 1993

rat olfactory tissue (determined in homogenates from olfactory mucosa scaled to whole tissue based on wet weight) 0.028 mg/ml 133.1 mg/h Bogdanffy et al., 1998

rat olfactory tissue (determined in homogenates from olfactory mucosa scaled to whole tissue based on epithelial volume) 0.028 mg/ml 39.9 mg/h Bogdanffy et al., 1998

rat olfactory tissue (determined by the gas uptake technique, scaled to whole tissue based on wet weight) 0.05 mg/ml 5.8 mg/h Bogdanffy et al., 1998

rat olfactory tissue (determined by the gas uptake technique, scaled to whole tissue based on epithelial volume) 0.05 mg/ml 45.4 mg/h Bogdanffy et al., 1998

Human olfactory tissue (determined by the gas uptake technique, scaled to whole tissue based on epithelial volume) 0.05 mg/ml 45.0 mg/h Bogdanffy et al., 1998

Human olfactory tissue (determined by the gas uptake technique, activity per specimen (dorsal meatus)) 0.05 mg/ml 0.9 mg/h Bogdanffy et al., 1998

Human olfactory tissue (determined by the gas uptake technique, scaled to epithelial cell volume) 0.05 mg/ml 1.94mg/h/mm 3 Bogdanffy et al., 1998

Rat oral cavity mucosa 0.49 mM (dorsal interior mucosa) 0.41 mM (dorsal exterior mucosa) 90 nmol/min (dorsal interior mucosa) 50 nmol/min (dorsal exterior mucosa) Morris et al., 2002R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 51 Tissue K m V max Literature
Mouse oral cavity mucosa 0.97 mM (dorsal interior mucosa) 0.91 mM (dorsal exterior mucosa) 24 nmol/min (dorsal interior mucosa) 2.6 nmol/min (dorsal exterior mucosa) Morris et al., 2002

rat liver microsomes 0.73 mM 23 μm ol/mg prot/min Simon et al., 1985

rat lung microsomes 6.1 mM 6.2 μm ol/mg prot/min Simon et al., 1985

rat plasma 4 mM 0.56 μmol/m g prot/min Simon et al., 1985

human plasma 7.1 mM 0.69 μmo l/mg prot/min Simon et al., 1985

Rat liver homogenates Not given in the report 133.3 μmol/min/g liver (homogenate) Strong et al., 1980

Mouse liver homogenates Not given in the report 140.0 μmol/min/g liver (homogenate) Strong et al., 1980

*values in brackets: different equations have been used for calculation; see Bogdanffy and Taylor, 1993.

Table 2: carboxylesterase activities (based on substrates other than vinylacetate)

Tissue Substrate K m V max Literature
rat respiratory

mucosa p-nitrophenylbutyrate 20.8 mM (males)

20.9 mM (females) 0.099 μmol/mg prot/min (males)

0.106 μmol/mg prot/min (females) Bogdanffy et al., 1987

rat olfactory mucosa p-nitrophenylbutyrate 34.1 mM (males)

31.2 mM (females) 0.605 μmol/mg prot/min (males)

0.593 μmol/mg protein/min (females) Bogdanffy et al., 1987

mouse respiratory

mucosa p-nitrophenylbutyrate 40.4 mM (males)

25.6 mM (females) 0.174 μmol/mg prot/min (males)

0.124 μmol/mg protein/min (females) Bogdanffy et al., 1987

mouse olfactory

mucosa p-nitrophenylbutyrate 23.1 mM (females)

21.8 mM (females) 0.467 μmol/mg prot/min (males)

0.444 μmol/mg pro/min (females) Bogdanffy et al., 1987

Rat respiratory tissue Methylmetacrylate 0.15 mM (microsomes) 14.3 nmol/mg protein/min (microsomes) Mainwaring et al., 2001R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 52 Tissue Substrate K m V max Literature
3.5 nmol/mg protein/min) (S9)*

Human respiratory tissue Methylmethacrylate Not determined 2.7 nmol/mg protein/min (microsomes)*

0.15 nmol/mg protein/min

(S9)* Mainwaring et al., 2001

Rat olfactory tissue Methylmethacrylate 0.14 mM (microsomes) 38.6 nmol/mg protein/min (microsomes)

12 nmol/mg protein/min (S9)* Mainwaring et al., 2001

Human olfactory tissue Methylmethacrylate Not determined 0.46 nmol/mg protein/min (S9)* Mainwaring et al., 2001

Rat liver microsomes Methylmeth acrylate 0.1 mM 46.5 nmol/mg protein/min Mainwaring et al., 2001

Human liver microsomes Methylmethacrylate Not determined 494 nmol/mg protein/min* Mainwaring et al., 2001

Human skin postmitochondrial fraction Fluazifop butyl 420 μM

(median from skin samples from different areas; n = 7) 61 nmol/min/g

(median from skin samples from different areas; n = 7) Clark et al., 1993

Rat skin postmitochondrial fraction Fluazifop butyl 248 μM ± 30.6

(mean, n=7) 740 nmol/min/g ± 90

(mean, n=7) Clark et al., 1993

Rat skin microsomes Fluazifop-butyl

Carbaryl

Paraoxon

Phenylacetate 14 ± 2.8 μM

32 ± 4.2 μM

950 ± 100 μM 0.02 μmol/min/g

0.2 nmol/min/g

ND

1.13 μmol/min/g McCracken et al., 1993

Rat skin cytosol Fluazifop-butyl

Carbaryl

Paraoxon

Phenylacetate 42 ± 2.8 μM

36 ± 3.8 μM

340 ± 50 μM 0.4 μmol/min/g

0.5 nmol/min/g

ND

3.44 μmol/min/g McCracken et al., 1993

Rat liver homogenate Ethyl acrylate 1.9 μmol/ml tissue 31.7 μmol/min/ml tissue Frederick et al., 1992R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 53 Tissue Substrate K m V max Literature
Rat lung homogenate Ethyl acrylate 1. 88 μmol/ml tissue 5.3 μmol/min/ml tissue Frederick et al., 1992

Rat skin homogenate Ethyl acrylate 5.45 μmol/ml tissue 0.86 μmol/min/ml tissue Frederick et al., 1992

Rat Arterial blood Ethyl acrylate 4. 6 μmol/ml tissue 0.18 μmol/min/ml tissue Frederick et al., 1992

* the values for rat S9 fractions and for all hum an tissues are for a single rate measured at a single substrate concentration of 1.0 mM.

Aldehyde dehydrogenase
Aldehyde dehydrogenase in the nose
Aldehyde dehydrogenase (ALDH) activities have been investigated in nasal homogenates (prepared from respiratory and olfactory mucosa ) from male F344 rats (Casanova-Schmitz et al., 1984). Activities were quantified by measur ing acetaldehyde-dependent formation of NADH at 340 nm during the first 1-5 min afte r addition of acetaldehyde. It could be demonstrated that in both resp iratory and olfactory mucosa two isozymes were present. The higher Km isozeyme of ALDH was five to eight tim es greater in respiratory than in olfactory tissue, whereas the low Km ALDH was comparable in respiratory and olfactory homogenates. Exposure to acetaldehyde vapor does not significan tly alter the enzyme activities in the nasal homogenates. Results are presented in table 3.
Aldehyde dehydrogenase activities in whole nasal tissue homogenates (epithelia type not specified) from male B6C3F1 mice, Sprague-Dawley rats, Syrian golden hamsters and Hartley guinea pigs were determined accordi ng to the method described by Casanova-Schmitz et al. (1984) (Morris, 1997). The estimated V max values for each species were normalised to the predicted minute ventilation of that species. In mouse, rat, and hamster the data were compatible with the assumption of two isozym es with an apparent high affinity and an apparent low affinity. In contrast, only a single form (high affinity) was detected in guinea pig nose homogenates. Total metabolic capacity (whe n normalised to predicted minute ventilation of the respective species defined as the sum of V max for both high- and low-affinity isozymes, averaged 0.04, 0.16, 0.56, and 0.14 μmol/min/w hole nose for nasal tissue of mouse, hamster, rat and guinea pig, respectively. The ratio V max /K m was significantly different between the species, the lowest activity observed in mouse (0.035 μmol/min/l/min) whereas hamster (0.13 μmol/min/l/min) and rat (0.22 μmol/min/l/min) s howed findings in the same range (Morris, 1997). For comparison, the data are also presen ted in table 3. The data may indicate the existence of quantitative species differences.
Since the nasal cavity epithelium is composed of a heterogeneous cell population, measurement of xenobiotic metabolizing enzy mes using homogenates could yield artificial results. Therefore, a similar approach as has been used to comparatively evaluate kinetic constants of carboxyl esterase , the gas uptake technique (see carboxylesterase activity in the nose), has been applied for acetaldehyde dehydr ogenase (Bogdanffy et al., 1998). Data from Casanova-Schmitz et al. (1984) were us ed for homogenate-derived values. K m

and v max values for aldehyde dehydrogenase activity in rats obtained by the gas uptake technique differedR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 54 from the values obtained using tissue homogena tes. However, when data obtained from homogenates were scaled to whole nose ba sed on epithelial volumes, comparable K m

and v max values were obtained by the two different me thodologies, which is illustrated in table 3.

Table 3: summary of acetaldehyde hydroxylase activities in human and animal tissues

Tissue K m V max Literatur

rat respiratory tissue

(determined in homogenates from respiratory mucosa) 20 mM (high Km)

3 x 10 exp-4 mM (low Km) 128 nmol/mg prot/min (high Km)

0.8 nmol/mg prot/min (low Km) Casanova-Schmitz et al., 1984

rat olfactory tissue

(determined in homogenates from olfactory mucosa) 22 mM (high Km)

1 x 10 exp-1 mM (low Km) 28 nmol/mg prot/min (high Km)

2.2 nmol/mg prot/min (low Km) Casanova-Schmitz et al., 1984

rat whole nose homogenate s 17 μmol/ml (high Km)

0.03 μmol/ml (low Km) 3.5 μmol/min/l/min (high Km)

0.27 μmol/min/l/min (low Km) Morris, 1997

mouse respiratory tissu e 41 μmol/ml (high Km)

0.07 μmol/ml (low Km) 1.35 μmol/min/l/min (high Km)

0.27 μmol/min/l/min (low Km) Morris, 1997

hamster respiratory tissue 12 μmol/ml (high Km)

0.02 μmol/ml (low Km) 1.47 μmol/min/l/min (high Km)

0.31 μmol/min/l/min (low Km) Morris, 1997

guinea pig respiratory tissue ND (high Km)

0.1 μmol/ml (low Km) ND (high Km)

0.64 μmol/min/l/min (low Km) Morris, 1997

rat respiratory tissue

(homogenate data from Casanova-Schmitz et al., 1984) 0.8 mg/ml 3.38 mg/h Bogdanffy et al., 1998

rat olfactory tissue

(homogenate data from Casanova-Schmitz et al., 1984) 0.8 mg/ml 0.94 mg/h Bogdanffy et al., 1998

rat respiratory tissue

(determined by the gas uptake technique, normalized to tissue 0.8 mg/ml 4.58 mg/h Bogdanffy et al., 1998R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 55 volume)

rat olfactory tissue

(determined by the gas uptake technique, normalized to tissue volume) 0.8 mg/l 1.48 mg/h Bogdanffy et al., 1998

human respiratory tissue

(determined by the gas uptake technique, normalized to tissue volume) 1.1 mg/ml 88.2 mg/h Bogdanffy et al., 1998

human olfactory tissue

(determined by the gas uptake technique, normalized to tissue volume) 1.1 mg/ml 2.31 mg/h Bogdanffy et al., 1998

Human oral cavity tissue

(Acetaldehyde as substrate) 75 – 83 mM (high Km)

0.2 – 33 μM (low Km) Dong et al., 1996; Yin et al., 1997

Human oral cavity 170 nmol/min/ml tissue

53 μmol/hr/ml tissue Dong et al., 1996

Human esophagus and stomach 75 – 85 mM Yin et al., 1997

Human saliva

(benzaldehyde as substrate) 85 mM 9 nmol/min/ml saliva

11.75 μmol/hr/ml saliva

Aldehyde dehydrogenase in the gastrointestinal tract
ALDH activity has been demonstrated in oral cavity tissue in humans (Dong et al., 1996; Yin et al., 1997). Human ALDH can be divided into two groups based on their affinity for acetaldehyde metabolism, those having a low affi nity (i.e. high Km of 75-83 mM) and those with a high affinity (i.e. low Km of 0.2 – 33 μM). Dong et al. (1996) report a low affinity ALDH in the human oral cavity with a specifi c activity of 170 nmol/min/ml tissue in the gingival at a substrate concentration of 20 mM acetaldehyde, which is approximately equal to a human oral cavity ALDH activity of 53 μm ol/hr/ml tissue. The human esophagus and stomach also contains low affinity (K m: 75 – 85 mM) ALDH activity (Yin, 1997). ALDH activity has also been demonstrated in human saliva. Sreerama and coworkers identified a low affinity ALDH (Km = 85 mM) in the human saliv a with a specific activity of 9 nmol/min/ml saliva at a substrate concentration of 4 mM benzaldehyde, which is equal to a ALDH activity of 11.57 μmol/hr/ml in human saliva (Sreerama et al., 1995).

Aldehyde dehydrogenase in tissues different from nose and oral cavityR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 56 In mammalians and humans, multiple forms of ALDH exist. Important to mention are the cytosolic aldehyde dehydrogenase of class 1 (ALDH1) and the mitochondrial aldehyde dehydrogenase of class 2 (ALDH2). ALDH1 and ALDH2 have been determined in a variety of human and animal tissues (Uotila and Ko ivusalo, 1997). However, Acetaldehyde was not degraded in the presence of diluted human (and also rat and mouse) plasma or whole blood, even when these systems were fortified with NAD (Strong et al., 1980).
In an assay which detects both formalde hyde dehydrogenase (FAD) and ALDH activity simultaneously, formation of formate as a marker of enzyme activities could be determined in normal human bronchial epithelial cells and in normal human bronchial explants (Ovrebo et al., 2002). Nevertheless, expression of ALDH enzy mes alone has not been determined so far in tissues of the upper respiratory tract of humans. Both ALDH1 and ALDH2 enzymes display Km values in the range of 0.5 mM for free formaldehyde (Mukerjee et al

. , 1992).

Cytochrome P450 2E1 (CYP2E1) It has been investigated whether CYP2E1 is involved in vinyl acetate metabolism. Rats were pretreated with the CYP2E1 inhibitor dially l sulphide. Nasal tissues were removed and assayed for CYP2E1 dependent p-nitrophenol hydroxylase activity. Nasal respiratory and olfactory microsomal CYP2E1 activity was i nhibited. However, CYP2E1 inhibition had no significant effect on nasal vinyl acetate extracti on. Therefore it was concluded that CYP2E1 does not contribute to local metabolism of vinyl acetate (Bogdanffy et al., 1999a). These investigations confirm previous results by Simon et al. (1985): after pre-treatment of rats with the CYP2E1 inhibitor diethyldithiocarbamate, the pharmacokinetics of vinyl acetate was not affected.

Glutathione transferases/glutathione conjugation Based on the facts that i.p. injection of vinyl acetate to female Chester-Beatty rats resulted in a decrease of hepatic glutathione level to 77% of the normal value 30 min after application (Boyland and Chasseaud, 1970) and that simila r decreases of hepatic non-protein sulfhydryls were reported after i.p. vinyl acetate injection to mice (300 mg/kg bw), Wistar rats (300 or 450 mg/kg bw) and guinea pigs (500 mg/kg bw ) (Holub and Tarkowski, 1982), it has been assumed that these findings may indicate conj ugation with glutathione. Unpublished results from DuPont Haskell Laboratories, however, did not confirm this assumption: no depletion of glutathione was noted in isolated nasal turbin ates incubated in nutritive medium supplemented with vinyl acetate. Direct incubation of vinyl acetate with glutathione-containing solutions resulted in no loss of vinyl acetate from the headspace indicating that vinyl acetate does not readiliy react with glutathione. However, it could not be ruled out , that glutathione conjugation might occur at extremely high doses of vinyl acetate.

Physiologically based modelling - inhalation A physiologically based pharmacokinetic (PBPK) model was developed to describe the deposition of vinyl acetate in the nasal cavity of the rat. The model estimates tissue exposure to vinyl acetate, acetaldehyde, and acetic acid in respiratory and olfactory mucosa with a submodel estimating potential intracellular pH i change associated with vinyl acetate exposureR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 57 (Plowchalk et al., 1997). The model takes into account the known data on vinyl acetate metabolism (see fig.1).
In this model nasal cavity is described by thr ee separate tissue compartments which are in contact with two airstreams flowing through th e nose (Morris et al., 1993; Kimbell et al., 1993). Fractional airflows were set 12% for the dorsal medial airstream (olfactory and respiratory mucosa) and 88% for the lateral/ven tral airstream (respiratory mucosa). In the model airflow is assumed to be unidirectional. Each tissue compartment was subdivided into layers representing mucus, epithelial cells, ba sal cells, and submucosal tissue. Mucus depth for both olfactory and respirator y mucosa was assumed to be 10 μ m, based on morphometric analysis. Depth of the respiratory mucosa was estimated to be approximately 40 μ m (epithelial cell layer 30 μ m, basal cell layer 10 μ m). The epithelial layer in the olfactory mucosa consisted of sustentacular cells (40 μ m), sensory cell bodies (not included since these cells do not contain vinyl acetate metabolising enzymes), and basal cells (10 μ m).
It was assumed that all enzymatic activity located in the submucosa was in the cell layers of the first 20 μ m. Enzymes involved in vinyl acetate metabolism are assumed not to be uniformly distributed throughout the nasal cavity . Histochemical studies (Bogdanffy et al., 1987) indicate that carboxylesterase activity is located primarily in the cytoplasma of epithelium cells (strong), basal cells (moderate), and weak to negligible in goblet cells and the overlying mucus of the respiratory mucosa. Di stribution of carboxylesterase activity in the olfactory tissue is primarily in sustentacular cells of the epithelia and Bowman’s glands. Overlying mucus, basal cells and neuronal (sensory) cells were negative.
Aldehyde dehydrogenase is demonstrated by i mmunohistochemical staining primarily in the epithelial and basal cells of respiratory mucosa , was weak to negligible in basal cells and Bowman’s glands and was absent in the sustentacular and sensory cells of the olfactory mucosa (Bogdanffy et al., 1986). Kinetic consta nts for carboxylesterase catalysed hydrolysis of vinyl acetate were estimated from in vitro determinations by Bogdanffy et al., 1993 (nasal tissue homogenates, converted from nmol/min/g protein basis to mg/h for the whole nose). Rates of aldehyde dehydrogenase activity in resp iratory and olfactory mucosa were estimated from literature (Casanova-Schmitz et al., 1984) by scaling the reported values (nmoles/min/mg protein from homogenates) to a whole nose basis, assuming a tissue protein content of 90 mg protein/g and tissue weights of 111 mg respiratory mucosa/nose and 141 mg of olfactory mucosal tissue/nose.

Data for the kinetic constants and distribution of acetyl-CoA synthetase within the nasal tissue are not available. The K m

and Vmax for acetyl-CoA syntheta ses were estimated from values reported for muscle tissue in Wistar rat (Knowles et al., 1974). It was assumed that the enzyme was equally distributed in each tissue compartment.
Vapour is transported to the air: tissue interf ace by diffusion. The molecular diffusivities were extrapolated from the diffusivity of ethanol in water (Morris et al., 1993).
Perfusion of blood through the nasal cavity wa s modelled as blood flowing only through the two submucosal compartments in the respirat ory and olfactory tissues at a total nasal perfusion rate of 13.2 ml/h (Morris et al., 1993). Symmetrical perfusion was assumed (6.6 ml/h).
In the pharmacodynamic submodel reduction of intracellular proton concentration was described to depend on intracellular buffering a nd transport to the extracellular compartmentR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 58 by the pH-dependent Na + /H + antiport. Na + /H + antiport activities are not available for rat nasal tissues and were estimated from proton efflux rate versus pH data for human leukocytes (Goldsmith and Hilton, 1992).
The dosimetry model was applied to data from a series of experiments in vivo (see above, Plowchalk et al., 1997) designed to measure upt ake and metabolism of vinyl acetate in the isolated upper respiratory tract of anaesthetised rats at exposure concentrations ranging from 73 to 2190 ppm during 1-h inhalati on (unidirectional flow, 100 ml/min). The best model fit for the experimental data on vinyl acetate extraction was achieved when a second carboxylesterase ‘high affinity pathway’ was included into the model. The high-affinity carboxylesterase was placed in the mucus compar tment of the model. Histochemical studies support this assignment (Bogdanffy et al., 1986). The kinetic constants derived for the high affinity pathway are similar to those that w ould be expected for many low molecular-weight substrates for cytochrome P-450 2E1. However, as the presence of P-450s in mucus is improbable the authors assume that the proposed high-affinity pathway is represented by an isoenzyme of carboxylesterase (see Bogdanffy et al. 1999a).
Model simulations (unidirectional flow, 188 ml/min , data at the end of 6 h-exposure of vinyl acetate for the first epithelial compartment in the tissue stack) predicted an exposure concentration-dependent increase in tissue con centrations of vinyl acetate, acetaldehyde and acetic acid in respiratory mucosa and also in ol factory epithelial mucosa (dosimeters given at vinyl acetate exposure concentrations of 50, 200, 600 and 1000 ppm). Steady-state concentrations of vinyl acetate in olfactory ti ssue are predicted to be much lower than in respiratory tissue at all exposure concentrati ons. Concentrations of acetaldehyde and acetic acid are expected to be approximately 1-2 or ders of magnitude greater than vinyl acetate concentrations in all tissue compartments.
At vinyl acetate expositions of ≤ 600 ppm the concentrations of acetaldehyde in nasal olfactory and respiratory epithelium were predicted to be less than 5 mM. The greatest reduction in intracellular pH i was predicted for respiratory mucosa .
A sensitivity analysis was conducted for four concentrations (5, 50, 200, and 600 ppm vinyl acetate) of vinyl acetate during 4-h exposures. The air flow and high-affinity metabolic parameters are the most important model parameters in relation to uptake of vinyl acetate by the rat nose (Plowchalk et al., 1997).
Bogdanffy et al. (1999b) have extended th e model of Plowchalk et al. (1997) by
(1) constructing a 5-compartment model of the rat nasal cavity
(2) a 4-compartment model of the human nasal cavity and
(3) air phase resistance to mass transfer from the lumen to the air: mucus interface.
This model is modified to account specifically for the dorsal anterior patch of olfactory epithelium for the human and the rat nasal cavity. To better characterise the vinyl acetate flux to the apical regions of the olfactory compar tments, the 5-compartment rat model divides the olfactory region into 2 compartments, a small dor sal anterior compartment (olfactory-1) and a larger posterior compartment (olfactory-2). The re spiratory mucosa on the ventral side is also divided. This model incorporates air phase resistance to mass transf er. In the model of Plowchalk et al. (1997) equilibrium between the air and the mucus phase was assumed. A detailed quantitative estimate of the various ce ll layer thicknesses comprising the olfactoryR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 59 and the respiratory mucosa of the rat and th e human is provided by B ogdanffy et al. (1998). Distribution of enzymes to specific compartm ents was based on histochemical localisation and is described in detail by Plowchalk et al. (1997). Enzyme kinetic constants for carboxylesterase and aldehyde dehydrogenase were obt ained from a whole tissue, in vitro, gas uptake technique (Bogdanffy et al., 1998). For ra ts a high affinity carboxylesterase pathway was optimised from vinyl acetate deposition data (rat nasal air stream 100 ml/min; exposure concentration ranged from 75 to 1500 ppm) in vi vo. These values were adopted for humans and were scaled to account for differences in tissue amount between rats and humans. The K m and Vmax for acetyl-CoA synthetase were estimat ed from values reported for muscle tissue in Wistar rat (Knowles et al., 1974), scaled to humans based on surface area. Mass transfer coefficients are results from hybrid comput ational fluid dynamics simulations on rat and human nasal cavity (Frederick et al., 1998). Blood perfusion was scaled to species based on cardiac output and nasal region based on surface ar ea. Total nasal perfusion estimated to be 0.3% cardiac output compares favourably w ith measured values (Stott, 1983). The pharmacodynamic submodel for estimating intr acellular acidification was described by Plowchalk et al., 1997. The PBPK model was us ed to examine the intracellular accumulation of acetic acid, acetaldehyde and protons produced during the metabolism of vinyl acetate at vinyl acetate expositions of 50, 200 and 600 ppm. At vinyl acetate exposure concentrations

< 600 ppm the concentrations of acetaldehyde in th e olfactory-1-compartment of rats and the single olfactory compartment of humans were pred icted to be <2 mM. Predictions of olfactory acidification for both rat and humans are presented. The change of intracellular pH is predicted to be slightly greater for human olf actory epithelium, than that of rats, per ppm inhaled vinyl acetate. Results for respiratory compartments are not shown

. To provide validation data for the applicati on of the model in humans (Bogdanffy et al., 1999b), controlled human exposures to inhaled vinyl acetate were conducted (Hinderliter et al., 2005). Air was sampled by a probe inserted into the nasopharyngeal cavity of five volunteers (two women, three men). Volunteers were administered a nasal aerosol spray consisting of 2 % lidocaine and 0.25 % oxymetazo line hydrochloride and were instructed to inhale and exhale through the nose. Sampling was carried out during exposure to labelled 13C1, 13C2-vinyl acetate during resting and light exercise at three exposure levels (1, 5 and 10 ppm nominally). Both labelled vinyl acetat e and the major metabolite acetaldehyde from the nasopharyngeal region were sampled at a calib rated flow rate of 12 l/h and analysed in real time utilising ion trap mass spectrometry (MS/MS). Measurements were taken every 0.8 sec in an exposure period of 2 to 5 min resulti ng in data during all phases of the breathing. The rate of sampling is rapid enough to capture many of the behaviours of vinyl acetate in the human nasal cavity including inhalation and exha lation. The sampling frequency is not short enough, however, to accurately capture the peak concentration in every breath. The method is free of interference from endogenous compounds a nd its detection limit is in the single digit ppb level. An acoustic rhinometry system was used to measure the cross-sectional area and volume of the nasal cavity. The complete set of human exposures resulted in a data set with over 22000 vinyl acetate and acetaldehyde data points. Data treatment was needed to identify the relevant experimental data, i. e. the peak concentrations for comparison of experimental data from bidirectional air flow (breathing cycl e) with model data from unidirectional flow. After treatment, the experimentally determined concentrations of both vinyl acetate and acetaldehyde were then compared to the predic ted concentrations calculated by applying the previously published human model (Bogdanffy et al., 1999b). The PBPK-model was exercised at the actual exposure concentrations. Other parameters were the same as presented in the human nasal model. Sensitivity analysis i ndicates that the air phase concentrations are most sensitive to the tissue:air partition coeffici ents, nasal airflow and the metabolic capacity of mucus layer . For each individual volunteer, the data from each exposure (i.e. three restingR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 60 and three light exercise periods) were character ised by a mean standard deviation, along with the model simulations. The concentrations of bot h compounds in airway appear to be linear as the model predicts. For vinyl acetate deposition data sets, the experimental measured concentrations are close to the model predicte d peak concentrations (r = 0.9). Acetaldehyde data are fitted with somewhat lower precision (r= 0.6). The authors give the explanation that increase in breathing rate resulted in difficulties of the analytical set up which resulted in less accurate measurements of peak concentrations. We are of the opinion, that the precision of the prediction is fair. Given the variations in the experimental data there is no significant interindividual variation and no signi ficant difference in nasopharyngeal concentrations of vinyl acetate and acetaldehyde based on exercise state. These results show that the human nasal model (Bogdanffy et al., 1999) predicts the expe rimental observations with regard to vinyl acetate concentrations and acetaldehyde wash-out in the airstream of human nasopharyngeal cavity in a concentration range from 1 to 10 ppm.
Physiologically based modelling - upper gastrointestinal tract
A physiologically based pharmacokinetic (PBPK) model was developed to describe the uptake and metabolism of vinyl acetate in th e upper gastrointestinal (GI) tract following ingestion of vinyl acetate via drinking water in mice, rats and humans (Sarangapani, 2001). The model describes the upper GI tract using three compartments, one each for the oral cavity, esophagus and forestomach, respectively. Each compartment is divided into a threelayered substructure. A top lumen layer provide s passage of the ingested vinyl acetate, a middle epithelial layer forms the target tissue for vinyl acetate toxicity, and a lower submucosal layer with blood perfusion clears th e parent chemical and its metabolites. This model takes into account the known course on vinyl acetate metabolism (see Fig. 1). A pharmacodynamic submodel (PD model) was developed to describe the intracellular pH i change associated with vinyl acetate exposur e (see also "physiologically based modellinginhalation"). The steady state pH of epithelial cells is determined by the balance between the rate of acid loading due to cellular metabolism, the cellular buffer strength, and the rate of proton transport due to special mechanisms. Th e PD model assumes the intracellular buffer to be a closed system containing bicarbonate and phosphate as buffers.
The upper GI tract epithelial and submucosal ti ssue thickness in rats and mice were measured from histological sectioning. The tissue thickness in humans was assumed to be same as in rats. Morris et al. (2002) measured carboxylesterase activity in the oral cavity tissue of rats and mice in homogenates of several tissue sa mples (see "in vitro data"). The composite activity values were scaled for tissue volume. Carboxylesterase activity in the esophagus and the forestomach was not measured. Human activity was obtained by allometrically scaling the mouse value to man. Aldehyde dehydrogenase (AL DH) activity has been demonstrated in oral cavity tissue in humans (Dong et al., 1996; Yin et al., 1997). Rates of ALDH activity in rats and mice oral cavity were assumed to be equal to that of humans. The acetyl-CoA synthetase activity was taken from values reported for mu scle tissue in Wistar rats (Knowles et al., 1974). Other model parameters were either obtaine d from the available literature (diffusivity, cardiac output, surface area) or were estimated from experimental studies (water intake). The antiport parameter for the PD-submodel was estim ated from values of cultured vascular muscle cells of rat or human lymphocytes.
The PBPK model was used to estimate steady st ate concentrations (24-h exposure) of acetic acid, acetaldehyde and intracellular proton concentration in the epithelial cell layer of the three tissue compartments for a range of vinyl acetate exposure concentrations from 400 to 10000 ppm in drinking water. The anterior tissu e compartment along the GI tract (oral cavity)R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 61 is the tissue with the highest uptake of vinyl acetate both in rats and mice (rat data are not shown) when compared to oesophagus and fore stomach (anterior-posterior gradient). The concentrations of vinyl acetate, acetaldehyde a nd acetic acid show a decline across the tissue layers in the mouse oral cavity for the three exposure concentrations used in the study. The amount of acetaldehyde, formed intermediately in the epithelial tissue of the mouse oral cavity is predicted to be about 0.16 and 0. 63 mM at an exposure of 400 ppm and 2000 ppm vinyl acetate, respectively. Although this PBPK model focuses on the upper gastrointestinal tract and does not include systemic components, it could be concluded from the model, that the clearance of vinyl acetate and its metabolites from the submucosal tissue into systemic circulation will be negligible. The model-derived exposure-dose relationship for intracellular proton concentration is sigmoidal. The reduc tion in pH from the resting-phase proton concentration is about 0.4 and 0.7 pH units at a vinyl acetate e xposure of 400 and 2000 ppm, respectively. Bogdanffy (2001) demonstrated this effect of intracellular acidification by exposing freshly isolated rat hepatocytes to vi nyl acetate and observing transient alterations in intracellular pH by use of a pH sensitive fluorescent marker that was located within the cytoplasm of isolated hepatocytes.
Sensitivity analysis reveals that the model-estimat ed internal dose-metrics are sensitive to oral esterase activity, tissue thickness and antiport char acteristics. Values for oral esterase activity and oral tissue thickness are available for the ra t and mouse, but not for humans. Similarly, antiport characteristics for rats cultured vasc ular muscle cells and human lymphocyte are available, but antiport data specific to the oral cavity epithelial cells are not available. Due to these missing data the exact variability in th e internal dose-metric in humans cannot be accurately predicted from the mouse-PBPK model.

Conclusion: Following inhalation and oral exposure of rats vinyl acetate is rapidly and effectively hydrolysed by carboxylesterases leading to th e formation of acetic acid and acetaldehyde which is further converted into acetic acid in the presence of aldehyde dehydrogenases. Further information on acetaldehyde and acetic aci d can be obtained from separate reports (e.g. reports prepared by the German MAK Commission).
The in vivo uptake of vinyl acetate was measured in the isolated upper respiratory tract of rats (anaesthetised rat, unidirectional flow, a nd 1 h-exposure). Disapp earance of vinyl acetate from the airstream was highest at the lowest exposure concentrations. Greater than 94% extraction was observed at vinyl acetate exposure concentrations of 76 ppm or below. With increasing exposure concentration (76 to 550 ppm ), extraction decreased progressively to about 40% and remained at this level up to concentration of approximately 2000 ppm. The impact on blood-flow extraction on vinyl acetat e deposition has been calculated by simulating vinyl acetate exposure in the ab sence of carboxylesterase activity. It could be demonstrated, that blood flow extraction accounts for less than 15 % of total vinyl acetate deposition. Hence, 15 % inhalative uptake can be taken as a worst case scenario for risk characterisation of systemic effects. However, it should be kept in mind, that vinyl acetate can be degraded in the blood with half lives between < 1 min and 4.1 min.
After oral administration of 297 mg/kg/bw 14 C vinyl acetate, 63 % of th e applied radioactivity was excreted as metabolites in exhaled air, urine and faeces. Based on the fact that vinyl acetate can be metabolized in the upper GI tr act epithelium it can be assumed, that a considerable extent of metabolism takes place presystemically which is supported by an oralR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 62 PBPK model (see below). This model led to th e conclusion, that clearance of vinyl acetate and its metabolites into the systemic circulation would be negligible. Hence, 63 % absorption would represent an overestimation of system ically available amounts of vinyl acetate. However, the PBPK model developed for oral vinyl acetate exposure did not include systemic components and furthermore, the model was de veloped in the absence of valid data for carboxylesterases in animal and human tissues. Based on the fact, that carboxylesterases in the GI tract are lower compared to carboxylesterase activities in nasal tissues, 50 % absorption can be assumed as a worst case for systemically available amounts of vinyl acetate after oral uptake. However, no clear assumpti ons can be made for systemically available metabolites of vinyl acetate (acetaldehyde, acetic acid).
There are no valid quantitative data on the syst emic bioavailability of vinyl acetate and its metabolites following dermal exposure. However, based on an acute dermal study in rabbits and based on the fact that carboxylesterase activ ities are lower in skin compared to nose or oral cavity, it can be assumed that systemic bioavailablility of vinyl acetate and/or vinyl acetate-derived metabolites is higher after derm al exposure when compared to oral or inhalative exposure. Therefore 90 % dermal abso rption should be taken forward to the risk characterisation.

Local metabolism was studied in human and rat nasal respiratory and olfactory tissue with whole turbinates in vitro. The studies indicat ed species differences of nasal respiratory carboxylesterase activities between rats and humans. The differences varied depending on the mode of data presentation (activity per speci men/activity per epithelial cell volume/activity scaled to whole nose). Therefore, no clear conclusions on the magnitude of species differences of nasal respiratory carboxylesterase activities can be drawn from these investigations. Rat aldehyde dehydrogenase activity in respiratory epithelium was about twice that of humans. Activities of the rat olf actory enzymes (carboxylesterase and aldehyde dehydrogenase) were about equivale nt to those of humans. The K m

values for both enzymes are not different between the two species. Aldehyde dehydrogenase activities determined in whole nasal tissue homogenates from mouse, rat, hamster and guinea pig showed significantly different ratios V max /K m

for the various species indicating the existence of species differences.
Vinyl acetate hydrolysis has been studied in vitr o in the oral mucosal tissues from the oral cavity of rats and mice. The hydrolysis activity of the oral tissues is at least 100-fold lower than that of the nasal tissues.
A physiologically based pharmacokinetic m odel was developed which describes the deposition of vinyl acetate in the nasal cavity of the rat. This model predicts steady state concentrations of the metabolite acetic acid afte r continuing 6 h-exposure in respiratory tissue which are approximately 13 times greater and in olfactory tissue which are approximately 2 times greater than those of acetaldehyde, the s econd metabolite. As the concentration of acids is indicative for the concentration of protons the model predicts the greatest reduction in intracellular pH i for respiratory mucosa. Hence, pH e ffects should be more pronounced in this tissue as compared to other tissues. This physiologically based toxicokinetic/toxicodynamic model for rat was modified for the olfactor y epithelium of the both human and rat nasal cavity. The change in intracellular pH is predicte d to be slightly greater for human olfactory epithelium, than that of rats. To provide validation data for this model, controlled human exposures at exposure levels of 1, 5 and 10 ppm to inhaled vinyl acetate were conducted. Air was sampled by a probe inserted into the nasopharyngeal cavity of five volunteers at bidirectional breathing through th e nose. Data from ion trap mass spectrometry measurements of labelled vinyl acetate and acetaldehyde were compared with data from the human nasalR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 63 model simulation. For the vinyl acetate da ta a good fit was demonstrated (r = 0.9). Acetaldehyde data are fitted with a somewhat lower precision. The results show that the human nasal model predicts the experimental observations with regard to vinyl acetate concentrations and the acetaldehyde washout in the airstream of human nasopharyngeal cavity in a concentration range from 1 to 10 ppm. However, uncertainties of the model consist in the enzyme kinetic data used to establish the m odel. Therefore, data on PK and PD outcome derived from the model should be taken with caution.
A similar PBPK model with a pharmacodynamic submodel for the upper GI tract of mouse, rat and man was developed to estimate oral vinyl acetate uptake, metabolism and the reduction in the intracellular pH. The model was used to estimate steady state concentrations (24 h exposure) of acetic acid, acetaldehyde a nd intracellular proton concentration in the epithelial cell layer for a range of vinyl acet ate exposure from 400 to 10000 ppm in drinking water. Details of model simulations are given for mouse. The intracellular pH reduction from the resting-phase proton concentration is a bout 0.4 and 0.7 pH units at a vinyl acetate exposure of 400 and 2000 ppm, respectively. Du e to missing human data (carboxylesterase activity and tissue thickness) the exact variab ility in the internal dose-metric in humans cannot be accurately predicted from the PBPK model.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 64 4.1.2.2 Acute toxicity

Animal data: Vinyl acetate exhibits low acute toxicity by th e oral and the dermal way of exposure but significant acute inhalation toxicity:

Oral
An oral LD 50 value of 3.73 ml/kg (= 3470 mg/kg) was determined in a range finding study in rats, using vinyl acetate (no data on purity): Doses of 8, 4 and 2 ml/kg body weight were administered by stomach intubation to 5 rats pe r dose. After application of 8 ml/kg all rats died within 24 hours, whereas after application of 4 ml/kg 3/5 rats di ed within 24 hours, and after application of 2 ml/kg no mortalities were observed. Clinical signs included sluggishness, gross pathology detected conges tion throughout the lungs and the abdominal viscera, the liver was mottled (no more data given) (Mellon Institute, 1969).

The same oral LD 50 value of 3.76 ml/kg (approximately 3500 mg/kg) for rats resulted from a study using 2% and 20% vinyl acetate emulsions with traganth. dyspnoe, tremors, apathy and diarrhoea were observed. At necropsy, no gross ch anges were detected (no further data given) (BASF AG, 1967).

Dermal A range finding study with rabbits demonstrated a dermal LD 50 value of 8.0 ml/kg (= 7440 mg/kg) for vinyl acetate (no data on purity): F our rabbits per dose (doses: 4, 8 and 16 ml/kg body weight) were immobilised during a 24-hours contact period with the compound retained under impervious sheeting on the clipped intact sk in of the trunk. The animals were placed in a hood with their heads protruding into the room to prevent the inhalation of the vapour. After occluded application of 16 ml/kg all animals died (clinical signs: convulsions within 15-30 minutes, crying, pupils turned upward, deaths within 25-70 minutes). After occluded application of 8 ml/kg 2/4 animals died with in 2 days (skin condition: erythema, oedema, necrosis). After occluded application of 4 ml/kg no mortalities and no clinical signs were observed. However, gross pathology revealed congestion of the lungs and liver, mottled spleen and kidney and prominent liver acini (Mellon Institute, 1969).

Inhalation An acute inhalation range finding study with rats resulted in an LC 50 value of 4490 ppm (= 15.8 mg/l/4 hours): Vinyl acetate vapour at metere d concentration, not checked analytically, was generated by feeding the liquid at a constant rate down the inside of a spirally corrugated surface of a minimally heated tube, through wh ich metered air was passed. This vapour was delivered in a glass exposure chamber to 6 ma le and 6 female rats per dose (doses: 8000, 4000 and 2000 ppm). While inhaling 8000 ppm all male and all female rats died during the exposure time (clinical signs: gasping at 10, pr ostration at 25, convul sions and death at 50 minutes to 1.5 hours). While inhaling 4000 ppm 2/6 male and 2/6 female rats died during theR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 65 exposure time (clinical signs: laboured breathi ng at 20 minutes, convulsions at 2.5 hours, death at 3 hours). After inhala tion of 2000 ppm no rat died (clinical signs: extremities red and irritated). Gross pathology detected haemorrhag es in lungs and tracheae of victims, but no remarkable effects after inhalation of 2000 ppm (Mellon Institute 1969). In another study 4000 ppm vinyl acetate (= 14.1 mg/l) killed 2-4/6 ra ts within an exposure time of 4 hours. No further data are submitted (Carpenter et al., 1949).
In a study on toxicity caused by inhalation of saturated vinyl acetate vapours (temperature used was 20 o C) 10/12 rats died within 3 minutes of exposure. Saturated vapours were produced by blowing air through a 5 cm layer of vinyl acetate and inhalation resulted in death of 0/12 rats after 1 minute, 10/12 rats after 3 minutes and 6/6 rats after 10 minutes of exposure. Clinical signs prior to death included severe irritation of mucous membranes, laboured breathing and narcosis. At necropsy, no gross changes were detected (BASF AG, 1967).

Human data:

No human data available.

Conclusion: Human data on the acute toxicity of vinyl acetat e are not available. In tests with rats LD 50 values were in two studies 3470 mg/kg a nd 3500 mg/kg, respectively. A dermal LD 50 value of 7440 mg/kg was determined from a range fi nding study with rabbits. Thus, vinyl acetate needs no labelling according to EU criteria with respect to acute oral and acute dermal toxicity. Inhalation toxicity testing, however, resulted in LC 50 values of 15.8 mg/l/4 hours and 14.1 mg/l/4 hours in rats; thus requiring classifi cation as harmful and labelling with „R 20, harmful by inhalation“.

4.1.2.3 Irritation

4.1.2.4 Corrosivity

Animal data:
Vinyl acetate has proven to cause irritation or corrosion to the skin of rabbits depending on the duration of the skin contact.
The primary skin irritation potential of vinyl acetate (stab., 99.9% purity) was investigated according to international test guidelines by se mi-occlusive application of 0.5 ml of the substance to the intact skins of one male a nd two female New Zealand White rabbits. Oedema was not observed, mean scores for eryt hema (observation 24, 48 and 72 hours after application) were calculated to be 0.7/0.3/0; er ythema disappeared in all animals after 3 days. No corrosive effects were noted on the treated skin of any animal at any of the measuring intervals and no other clinical signs of subs tance related effects were observed (RCC 2003a).R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 66 In a Draize skin test with rabbits similar to current EU guidelines vinyl acetate caused skin irritation: Six rabbits were exposed by occlus ion to 0.5 ml of undiluted liquid vinyl acetate each. Effects on intact skin included erythema (scores 1/1/1.5 for 4, 24, 72 h) and oedema (scores 2.7/2.2/0.3 for 4, 24, 72 h). Erythema observation at 4 and 24 h was difficult due to red staining of the application site. Subdermal haemorrhage was observed in one animal after 72 hours (Industrial BIO-Test Labs. Inc., 1972).
Mild irritation after 5-15 minutes of exposur e and necrosis after 20 hours of exposure was demonstrated in a further skin irritation st udy: An unknown number of rabbits were dermally exposed to unknown amounts of undiluted vinyl acetate for 1, 5 and 15 minutes and for 20 hours (no information on the kind of exposure). No signs of irritation were observed after 24 hours following 1-minute exposure; slight erythe ma occurred 24 hours after the 5- and the 15- minutes exposures. Mild erythema and mild oedema were observed at 24 h after the 20-hours exposure. Necrosis was observed 8 days af ter 20 hour-exposure to the compound (BASF AG, 1967).
Long time occlusive dermal application of 8 m l/kg killed 2/4 rabbits within 2 days; these animals showed necrosis at the application s ite (Mellon Institute, 1969, see chapter on acute toxicity).
Application of 1-2 drops of the undiluted substance (stabilised with 3-5 ppm hydroquinone) to the eyes of rabbits after 1 hour mild (+) erythema, pronounced (++) oedema and after 24 hours mild (+) erythema and mild (+) opacity . No signs were observed after 8 days. The number of test animals was not given, scores were mild (+), pronounced (++), very strong (+++) (BASF AG, 1967).
Vinyl acetate caused mild irritation in the eyes of rabbits which was reversible within 48 h after application. The test was performed acco rding to the current guidelines on acute eye irritation (OECD 405, B.5 92/69 EEC). The am ount of 0.1 ml of undiluted vinyl acetate (purity of 99.9 %) was placed in the left conj uctival sacs of one male and two female New Zealand White rabbits. One hour after application mild redness and chemosis of conjunctivae were observed, which were fully reversible in all animals after 48 and 24 h, respectively. No changes of corneal opacity and iris were obser ved. The mean scores determined after 24, 48 and 72 h and relevant for classification were 1/ 0/0 for redness and 0/0/0 for chemosis, corneal opacity and iris (RCC, 2003c).

Five rabbits that received 0.1 ml undiluted vi nyl acetate (clear liqui d, purity not given) showed mild reddening 24 to 48 hours after app lication. In three animals chemosis was observed after 24-48 hours (without any scores). Overall, mild eye irritation was concluded (Hoechst, 1970).
Vinyl acetate has proven to cause severe irritation in the respiratory tract of rats (see chapters on acute toxicity, 4.1.2.2 and repeated dose toxicity, 4.1.2.6).R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 67 Human data:
Exposed workers are principally exhibiting local irritant reactions of the skin, eyes and respiratory tract (information by the vinyl acetat e industry, without further details). Other, more substantiated information on irritating effects on humans is not available.

Conclusion:
Except a general notice from occupational use no substantiated human data on irritation/corrosion caused by vinyl acetate are available.
Due to the only valid tests (RCC, 2003a and c) m ild irritative effects on the skin and eyes of rabbits were observed that do not warrant classi fication. Earlier studies of limited reliability indicated pronounced irritation or corrosion of skin after extended exposure periods.

Acute inhalation tests with rats demonstrated se vere irritation in the respiratory tract of the animals. Thus, vinyl acetate should be labe lled „R 37 Irritating to respiratory system according to the Annex I rules. In September 2007 the TC C&L agreed on R37.

4.1.2.5 Sensitisation

Animal data:
The potential of undiluted vinyl acetate (commercial grade) to produce delayed contact hypersensitivity in guinea pigs was evaluated w ith the Buehler method (adoption of method of Ritz and Buehler). The study was performed with 20 animals in the test group and 10 animals in the control group.
Animals were induced 3 days per week w ith undiluted commercial grade vinyl acetate (usually containing 1.5-20 ppm hydroquinone as a stabiliser) under an occluded patch (6 hours per exposure) placed in a restrainer. Afte r a rest period of 2 weeks the animals were challenged with 25% vinyl acetate in acetone. The in cidence and severity of skin responses in the test group (grade 1 responses: slight but c onfluent, or moderate patchy erythema; grade + responses: slight patchy erythema) were greater than those produced by the naive control: Twenty four hours after removal of the test 6/20 test animals demonstrated effects grade 1 and 14/20 effects grade + , 48 hours after removal 3/20 test animals showed grade 1 and 17/20 grade + effects; in the control group no grade 1 and 7/10 grade + effects were observed. Thus, the testing laboratory concluded that vinyl acet ate was a skin sensitiser in guinea pigs.
Since the vinyl acetate stabiliser hydroquinone (commercial grade vinyl acetate usually contains 1.5 to 20 ppm hydroquinone) has been reported to cause skin sensitization in concentrated form, 5 ppm hydroquinone in acetone was also tested (Buehler test). Following primary challenge no grade 1 responses occurred. The incidence of grade + responses (slight, patchy erythema) in the hydroquinone-treated group (7 of 10) was compared to that of the naive control group (7 of 10). Since incidence a nd severity of the responses were essentially comparable between these 2 groups, the testi ng laboratory concluded that sensitization had not been induced by hydroquinone (Hill Top Biolabs Inc., 1995).R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 68 Vinyl acetate (purity > 99.9%) was tested in a Local Lymph Node Assay (LLNA). A total of seven groups each of five female mice (CBA stra in) were used. Five groups were treated with Vinyl acetate at concentrations of 5%, 10%, 25%, 50% (w/v) in acetone: olive oil, 4:1 (v/v) and 100% (undiluted) by topical application to the dorsum of each ear lobe (left and right) on three consecutive days. A negative control group was treated only with the vehicle. A positive control group was treated with Alpha-Hexylci nnamaldehyde at a 25% concentration. The application area of both ears of each mouse was measured for ear thickness prior to the first application, daily 24 hours after each dosing and pr ior to necropsy. Five days after the first topical application the mice were intrave nously injected into the tail vein with 3 H-methyl thymidine (equal to 19.8 μC/mouse). Approximately five hours after the intravenous injection the mice were killed, auricular lymph nodes we re excised and pooled per animal. Single cell suspension were prepared, washed and inc ubated with trichloroacetic acid overnight. 3 Hthymidine incorporation was measured in a sc intillation counter. All animals had survived and systemic clinical were not noted. Local inflamma tory reactions (increased ear thickness) were noted in all groups with the exception of the vehicle control group and the 5%-group. The Stimulation Index (SI) was below a 3-fold incr ease in all groups with the exception of the positive control group. Mean SI values were 2.0, 2.4, 1.9, 1.7, 1.3, 16.6 for the 5%, 10%, 25% 50%, 100% test solution and the positive control (25% HCA) (5%)(RCC, 2003b).
Data on respiratory sensitization are not available.

Human data:
No allergic reactions were observed in twenty -one chemical operators who worked in vinyl acetate production for a mean period of more th an 15 years: These operators, evaluated for overall health, were presumably exposed to levels of vinyl acetate in the air in concentrations of approximately 5-10 ppm for the duration of their service. In workers which came into contact with vinyl acetate (average exposure to 17.6-65 mg/m 3 over 15.2 years, with intermittent exposures near 180 mg/m 3 ) no allergic reactions were observed. However, no patch test was performed (Deese and Joyner, 1969).
In workers with frequent and intensive dermal exposure to vinyl acetate, no allergic skin reactions could be detected. However, no patch test was performed (Wacker-Chemie, 1995a, Klaschka and Vossmann, 1994).
Vinyl acetate is not included in standard patch test kits and this may be the reason that data on patch testing with this substance are not availabl e. Thus, the inconclusive or negative data as cited above cannot be used as evidence that vinyl acetate may not cause sensitization by skin contact.
There is no information available on the poten tial for vinyl acetate to produce respiratory sensitization in humans.

Conclusion:

No cases of skin sensitization from the handli ng of vinyl acetate in the workplace have been reported in the last years. However, the da ta obtained for humans at the workplace are of limited value for assessing skin sensitising poten tial of vinyl acetate. There are no data onR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 69 negative patch tests to substantiate the conclu sion that the substance has no skin sensitising potential. The absence of positive findings and th e absence of adequate data do not allow the conclusion that vinyl acetate has no skin sensitising potential.

Results from an animal skin sensitization st udy (Buehler Test) showed a moderate skin sensitising potential of vinyl acetate (commercial grade). With the use of the Local Lymph Nodes Assay (LLNA) no positive stimulation respons es were detected at concentrations of 5% - 100%. Increased ear thickness after treatment with concentrations >5% support the skin irritative properties seen after prolonged dermal exposure. However, the results obtained with this LLNA may not fully reflect the potentia l of concentrations >10%, since higher concentrations of vinyl acetate show increas ing volatility, due to decreased proportions of acetone/olive oil. As a result, samples applied to the skin of the ear may have been quickly evaporated. SI values support this assumption, since a constant decrease was obtained for concentrations > 10%.
Overall, the outcome of both st udies may indicate that vinyl acetate is not devoid of a skin sensitising potential. The results of the LLNA do confirm the weak-moderate effects seen in the Buehler test. However, since the positive th reshold level was not exceeded in the LLNA, classification and labelling with R 43 is not warranted. The LLNA was given a higher reliability since pure vinyl acetate was used for testing whereas a commercial grade test substance was applied in the Buehler test. In a ddition, the Buehler test was not fully compliant to the EU testing guideline due to some deviations of the test protocol.

No direct information is available from studies in humans on respiratory sensitization. In view of the widespread use, the absence of any re ports suggests that vinyl acetate may not be a respiratory sensitiser.

4.1.2.6 Repeated dose toxicity

Animal data:
Inhalation exposure

- In a less well documented study (Gage, 1970, no details on parameters of laboratory investigations, no data on food consumpti on, no list of organs for microscopic examination or results) groups of 4 male and 4 female Alderly Park rats were exposed to vinyl acetate (no data on purity and details on exposure chamber) at 100, 250, 630 or 2000 ppm (calculated as 360, 890, 2200 or 7100 mg/m3) 6 hours/day, 15 days in about 3 weeks. Animals exposed to 2000 ppm showed signs of eye and nose irritation, respiratory difficulties, and reduced body weight gain (no quantitative data). At the concentration of 2000 ppm, increased numbers of macrophages in the lungs were observed. Females of the 630 ppm- and 250 ppm-groups also had lower body weight gain. Autopsy revealed normal organs up to 630 ppm, at 250 ppm blood and urine tests were reported to be normal. There were no data on these tests for other dose groups. Based on this short note, the NOAEC for systemic effects was 100 ppm (360 mg/m 3) in female rats and at 630 ppm (2200 mg/m3) in male rats. The NOAEC for local effects on the respiratory tract was 630 ppm (2200 mg/m3).

- In a 4-week range-finding study (Owen, 1979a,b ) groups of 5 male and 5 female SpragueDawley rats and CD-1 mice were exposed to 0, 50, 150, 500 or 1000 ppm (calculated as 0,R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 70 180, 540, 1800 and 3600 mg/m3) of vinyl acetat e vapour, 6 hours/day, 5 days/week (no data on the purity of the test substance, acetaldehyde concentration in the exposure chamber 8 ppm). The dose level of the 50 ppm group was increased to 1500 ppm (5360 mg/m3) on exposure day 8 (in mice) and on expos ure day 10 (in rats) as marked clinical effects had not been observed at 1000 ppm. The studies did not incorporate examinations on haematology, clinical chemistry or urinalysis. Multiple samples from tissues/organs were preserved, but were not processed for histopathology. The reports available did not contain figures and tables. Mice exposed to 150 ppm and rats exposed to 500 ppm or higher intermittently showed hunched posture and respiratory distress with dose-related frequencies and severity grades. A dose-rela ted (non significant) d ecrease in body weight gain was noted in female rats of all treatme nt groups and in male rats of 50/1500 ppm- and 1000 ppm groups. Mean body weight gain was d ecreased in all treated mice, however it gained significance only in males and female s of the 1000 ppm group and in females of the 50/1500 ppm group. No treatment-related macroscopic abnormalities were observed at necropsy, the absolute and relative weights of spleen were decreased in male mice exposed to 1500 ppm and in male rats exposed to ≥ 1000 ppm. Histopathological examinations of respiratory tissues from mi ce of all concentration groups were performed subsequently and revealed hyperplastic and me taplastic changes in the epithelium of the respiratory tract (no further details, Owen, 1980a). Concentrations ≥ 150 ppm in mice and ≥ 500 ppm in rats produced clinical signs of respiratory tract irritation. As growth retardation was not significant, the NOAEC for systemic effects was 1500 ppm in rats and mice (5360 mg/m3). However with respect to th e limited test parameters, the confidence of statements on systemic toxic effects wa s low. The NOAEC for local effects on the respiratory tract was 50 ppm in mice (180 mg/m3) and 150 ppm in rats (540 mg/m3).

- The effects of vinyl acetate exposure on nasal epithelial cell proliferation were evaluated in male Sprague-Dawley-derived rats (5 rats per group) exposed for 1, 5, or 20 days (6 h/d, 5 days per week) to 0, 50, 200, 600, or 1000 ppm (Bogdanffy et al., 1997). The test material was 99.9% pure. Impurities consiste d of acetaldehyde (100 ppm), acetic acid (50 ppm), hydroquinone stabiliser (3-7 ppm), et hylacetate (300 ppm), and methylacetate (200 ppm). Respiratory tract tissues were examined for gross alterations. Cell proliferation was assessed by histopathological evaluation of five cross sections of the nose and by immunocytochemistry (level of BrdU inco rporation following BrdU injection 16 hours after the last exposure). Data on feed cons umption were not reported. There were no changes in body weight except to a reduced mean body weight in the 1000 ppm group from day 3 (maximum reduction on day 5 -14%) through day 26 (-11%). Following a single exposure, rats of the 600 and 1000 ppm groups showed concentration-related minimal to moderate degeneration, necrosis and exfoliation of the olfactory epithelium and only at 1000 ppm minimal degeneration and necrosis in the respiratory epithelium. Following 5 or 20 exposures, additional lesions consisted of mild to severe regenerative hyperplasia with attenuation and/or disorganis ation of the olfactory mucosa, occasionally squamous metaplasia and only after 20 expos ures minimal to severe degeneration and atrophy of olfactory nerve bundl es. Respiratory epithelium showed minimal regenerative hyperplasia and only after 20 exposures mini mal squamous metaplasia. A significant concentration-related increase in cell labelling was observed in the basal cells of the respiratory and olfactory epithelium follo wing a single 6-hour e xposure to 600 and 1000 ppm vinyl acetate. No significant difference in labelling indexes of the respiratory and olfactory epithelium was observed after 5 days of exposure. Following 20 days of exposure, the response in the respiratory epithelium remained near control levels while that in the olfactory epithelium was signi ficantly higher in the 600 and 1000 ppm groupsR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 71 than control levels. Again basal cells were la belled, but additional labelling of cells were seen in the adluminal regions of regenerating epithelium. The NOAEC for nasal effects was 200 ppm in this study (710 mg/m3).

- In a 90-day inhalation study gr oups of 10 male and 10 female Sprague-Dawley rats and CD-1 mice were exposed to vinyl acetate va pours (purity of test substance 99.9%) at concentrations of 0, 50, 200 or 1000 ppm ( calculated as 0, 180, 710 or 3600 mg/m3), 6 hours/day, 5 days/week (Owen, 1980a,b). Histopa thological sections from several tissues from all animals of the high concentration and the control groups were examined, the nasal turbinates (without any information about the number of sections) were included. In mice, histopathology examinations were extended to 2 levels of nasal turbinates, 3 lobes of the lungs and 3 levels of the trachea for a ll animals of the low and intermediate groups. The reports did not contain histopathology summa ry tables; tabulated data were totally absent in the mouse study report. The findings of the nasal mucosa were not separately reported for the respiratory and olfactory epithelia. No feed consumption data are available. Exposure of rats to 1000 ppm vinyl acetate resulted in significantly decreased body weight gain (final body weight -19% in both sexes), clinical effects (intermittent incidence of respiratory distress, hunched pos tures and ruffled fur), increased lung-tobody weight ratio (assumed as due to lung c ongestion), and histomorphological changes in the respiratory tract (mild histiocytic alve olitis). The authors assumed that increased relative lung weights were related to conges tion. This association seems not to be plausible because lung congestion was reported for one incidental death in the control group. The quality of the rat study was considered to be restricted, because most control and high dose rats suffer from parasitic inf ections indicated by eosinophilic gastritis and colon nematodiasis. Many rats from both gr oups had peribronchial/perivascular lymphoid hyperplasia, alveolar histiocytosis/ his tiocytic pneumonia, chronic tracheitis and laryngitis, and lympadenitis. Except a higher inci dence of alveolar histiocytosis in high dose rats (19/20 vs. 12/20 controls) no treatme nt-related toxic effect was seen in the organs examined. – The olfactory regions of nasal sections of 4 male and 3 female rats exposed to 1000 ppm were reviewed (Hardisty et al., 1999). The most severe lesions were seen in the dorsal medial meatus of the ante rior nasal passages (level II), lesions extended posteriorly to the dorsal medial meatus of levels III and IV and the dorsal scroll of the third ethmoturbinates. Lesions were char acterised by postdegenerative atrophy of the olfactory epithelium and focal erosion, with associated infiltration of neutrophils and eosinophils. Some losses of Bowman’s glands and of nerve bundles in the lamina propria were observed in the most severely affected areas. There was only a minimal evidence of regeneration of the affected epithelium.

- In mice, exposure to 200 ppm vi nyl acetate produced transient signs of respiratory distress and hunched posture through the first 9 days of exposure. High dose males and females exhibited ruffled fur, hunched posture and re spiratory distress. Six high dose females, three high dose males and two male controls di ed during the course of the study, all except one death were associated to the routine blood sampling. There was a significant reduction of body weight gain in the groups of hi gh dose males (-18%) and females (-17%). Microscopic changes including inflammato ry, transudation and eosinophilic homogenous material in the nasal passages, hyperplasia of goblet cells hyperplastic and metaplastic changes of the nasal turbinates, (suspected) ar eas of epithelial metaplasia or hyperplasia of the trachea with loss of ciliate d epithelium and epithelial atrophy, multifocal bronchiolitis, bronchiectasis, bronchial epithelial meta plasia and hyperplasia, and occasional bronchiolar and bronchial exudation were seen in high dose male and female mice. Mild to slight inflammation of the nasal turbinates were observed in one low dose female andR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 72 three intermediate dose females, a very mild accumulation of eosinophilic homogenous material was observed in the nasal passages of two low dose female mice, and two mid dose females exhibited mild bronchiolitis. The authors considered these mild changes to be similar to that seen in the control animals, although no findings were reported for control mice. Although similar lesions may occasionally be observed in historical controls, these findings were consistent to those of the high dose mice. Therefore this interpretation is considered to be equivocal. On the limited data of this studies, a NOAEC for systemic effects was 200 ppm (710 mg/m3) fo r the rat (due to growth retardation at 1000 ppm) and 50 ppm (180 mg/m3) for the mouse (due to hunched posture at 200 ppm and above) However, it is uncertain whether hunched posture could be interpreted as a non-specific toxic effect, more likely it seems to be associated with the respiratory symptoms. The NOAEC for local effects on the respiratory tract was 200 ppm (710 mg/m3) for rats due to respiratory distress a nd higher incidences of alveolar histiocytosis and 50 ppm (180 mg/m3) for mice due to respir atory distress at 200 ppm assumed that the morphologic lesions of the respiratory tract of mid and low dose were incidental.

- In a combined chronic toxicity and carci nogenic study (Owen, 1988; Bogdanffy et al., 1994b) male and female Sprague-Dawley rats and CD-1 mice including 60 animals per sex per dose and three satellite groups of 10 of each species and sex for interim evaluation at week 53 and week 83 and recovery studi es (70 weeks of exposure followed by 15/16 weeks of recovery) were exposed by inhalati on to vinyl acetate vapour in concentrations of 0, 50, 200, and 600 ppm (equivalent to 0, 178.5, 714, 2142 mg/m3) over a period of 2 years (6 hours/day, 5 days/week). The test material contained impurities of acetaldehyde ( ≤ 65 ppm), acetic acid ( ≤ 10 ppm), water ( ≤ 472 ppm) and hydroquinone ( ≤ 1 ppm). Examinations on hematology, clinical chemis try, urinalysis and gross and microscopic abnormalities were performed on satellite groups at week 51 and 81 and on the end of the main study. At the end of the study, a signifi cant reduction in weight gain (no quantitative data available) was observed among rats and mice in the 600 ppm groups (final body weights -10% in males to -15% in female s). Also, the overall body weight gain of 200 ppm mice was significantly lower than that of the control groups (no quantitative data reported). Increases in weight gain were noted in the recovery groups of high dose male rats, the high dose male mice and females of a ll doses. Exposed animals of both species at all concentrations showed rough haircoat and hunched posture. There were effects on blood glucose (reduced in high dose female rats ) and urinary parameters (decreased urine volume and pH values and increased specifi c gravity in high dose rats) which were attributed to (nonmeasured) reduced food and water consumption. The survival rates of 600 ppm female rats were higher than that of controls, (64% vs. 36%), but overall there was no treatment-related increase in mortality in both species.
In both species exposure-related effects were confined to the respiratory system. Mean lung weight was increased in high dose rats (relative weights) and mice (absolute and relative weights). Lung weight was also affected in low and intermediate dose rats and intermediate dose mice, however the effect was inconsistently found after several intervals of treatment. In both species of each sex, vinyl acetate induced morphological nonneoplastic lesions in the nasal cavity of the 200 and 600 ppm groups and in the trachea (mice only) and in the lungs of th e 600 ppm groups (Tables 4.1.2.6 A + 4.1.2.6 B). In addition, some high dose female mice showed hyperplastic lesions in the larynx (no data on exact number of affected animals) , a focus of squamous epithelial hyperplasia with dysplastic changes was noted in a singl e female. - In rats, nasal lesions were restricted to the olfactory mucosa consis ting of atrophy and basal cell hyperplasia, in severe cases lesions were accompanied with replacement of respiratory epithelium, non-R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 73 keratinising squamous metaplasia, thickened and edematous submucosa, loss of nerve bundles and Bowman’s glands or with hyperpla sia of glandular structures. In the 200 ppm groups, lesions were restricted or most pr onounced in the anterior part of the dorsal meatus, which is normally covered by the ol factory epithelium. At 600 ppm, the lesions extended to the posterior parts of the olfact ory epithelium. In this area, a layer of stratified non-differentiated epithelium cont aining small foamy structures resembling nerve bundles and groups of epithelial cells resembling acinar cells of the Bowman’s glands was evident in many rats of the 200 ppm groups and a few rats of the 600 ppm groups. They were often accompanied by keratinising squamous epithelium and epithelial nest-like infolds. The authors considered this being a complete regeneration. - Mice of the 200 and 600 ppm groups showed similar lesions, however differed in that the olfactory epithelium was replaced by respiratory-like ep ithelium and the sustentacular cells were more frequently hypertrophic and showed lo ss of sensory cells. In high dose mice only, nonkeratinizing squamous metaplasia of the re spiratory epithelium, nasal inflammatory infiltrate and exudate were observed. Also, the trachea was affected showing hyperplastic epithelium, occasionally with epithelial flattening, exfoliation, metaplasia and fibroepithelial projections. In the l ung of both species exposed to 600 ppm bronchial/bronchiolar epithelium was flattene d or exfoliated, and showed intraluminal fibroepithelial projections and alveolar (o r interstitial) accumulation of macrophages with pigments, foamy or eosinophilic appearance.
Treatment-related nasal and pulmonary lesions in rats and mice were similar in the interim and recovery groups to those seen in the main study and occurred at about the same incidence and the same or lower degree as in the main study. In the lungs bronchial exfoliation was not observed in any of the in terim or recovery group rats. Cessation of treatment for 16 weeks showed no recovery from olfactory atrophy in rats and mice, although high dose mice did show a tendency to recover from the inflammatory changes and epithelial hyperplasia. No hyperplasia of the tracheal epithelium was seen in the recovery group of mice.
In summary, the chronic inhalation of vinyl acetate vapour ≥ 200 ppm induced cytotoxic effects on the epithelia of the upper and lo wer respiratory tract of rats and mice accompanied by nasal inflammation in mi ce. The NOAEC for local effects on the respiratory tract was 50 ppm for both speci es (180 mg/m3). Based on the reduction of body weight gain, the NOAEC for systemic t oxicity was 200 ppm for rats (710 mg/m3) and 50 ppm for mice (180 mg/m3).R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 74 TABLE 4.1.2.6 A

Summary of statistically significan t non-neoplastic changes in lungs and nose in rats: main study

Incidence of Lesions Other than Tumors a
Males Females Concentration (ppm): Control 50 200 600 Control 50 20 0 600 Lungs: (58) (59) (60) (60) (60) (60) (60) (59)
Bronchial exfoliation very slight

slight moderate 0 0 0 0 0 0 0 0 0 8** 26**

2 0 0 0 0 0 0 0 0 0 0
4 0 Intraluminal fibrous projections very slight

slight moderate

severe 0 0 0 0 0 0 0 0 0 0 0 0 16 *** 14 ***
1 0 0 0 0 0 0 0 0 0 0 0 0 0 3 28 ***

8 **

1 Pigment macrophage very slight

slight moderate 1
1 0 0 3 0 0 3
1 0 33 ***

2 0 6 0 0
4 0 0
1 0 1 10
4 Peribronchiolar/perivascular lymphoid aggregates very slight

slight moderate 5 15
1 1 18
4 0 *
21
1 0 *
14
2 0
11
2 1
14
1 2
14
2 0 23 *

5
Nose: (59) (60) (59) (59) (60) (60) (60) (59) Olfactory epithelial atrophy very slight

slight moderate

severe 0 0 0 0 1
2 0 0 4 47 ***
2 0 0 7 * 33 *** 10 ** 0 0 0 0 1 0 0 0 4 23 ***
0 0 0 18 *** 30 ***
3 Olfactory epithelial squamous metaplasia very slight

slight moderate

severe 0 0 0 0 0 0 0 0 0 0 0 0 2 12 ** 9 **

1 0 0 0 0 0 0 0 0 5 0 0 0 4 26 ***

7**

0

a Figures in parenthesis present the numbe r of animals from which this tissue was examined microscopically. Significance of differences in a pairwise (Fisher ́s) test between each treatment and control incidence is indicated by * p < 0.05, ** p < 0.01, *** p < 0.001. Cited from Bogdanffy et al. (1994b)R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 75 TABLE 4.1.2.6 A Summary of statistically significan t non-neoplastic changes in lungs and nose in rats: main study (Continued)

Incidence of Lesions Other than Tumors a
Males Females Concentration (ppm): Control 50 200 600 Control 50 20 0 600
Nose: (59) (60) (59) (59) (60) (60) (60) (59) Olfactory epithelial regeneration very slight

slight moderate 0 0 0 0 0 0 3 30***

2 0
1 0 0 0 0 0 0 0 3 16***

3 2 7**

0 Olfactory epithelial inflammatory cell infiltrate very slight

slight moderate 0 0 0 0 0 0 0 0 0 1 7 *

1 0 0 0 0 0 0 0 0 0 0 5*
1 Epithelial nest-like infolds very slight

slight moderate 0 0 0 0 0 0 0 0 0
1 15***

1 0 0
5
5 0 0 0 0 0 0 0 0 1 0
5 0 0 0 5*
2 Olfactory epithelial leukocytic exudate very slight

slight moderate

severe 0 0 0 0 0 0 0 0 0 0 0 0 0 11***

2
1 0 0 0 0 0 0 0 0 1 0
1 0 0 5 *
3 0 Basal cell hyperplasia very slight

slight moderate

severe 2 0 0 0 5 0 0 0 3 40*** 11***

0 1 21*** 22***

2 0 0 0 0 0 0 0 0 7* 24***

3 0 0 35*** 16***

0 Turbinate leukocytic exudate very slight

slight moderate

severe 0
4 3 0 2 8 6 0 0
5 3 0 0
5 8
1 1
4 0 0 1 3
1 0 3 3
1 0 1
7 7 **

0 Submucosal inflammatory cell infiltrate slight moderate

severe
very severe 2
1 0 0 0 3 0 0 1
1 0
1 2 6
1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 5 *
0 0

a Figures in parenthesis present the numbe r of animals from which this tissue was examined microscopically. Significance of differences in a pairwise (Fisher ́s) test between each treatment and control incidence is indicated by * p < 0.05, ** p < 0.01, *** p < 0.001, cited from Bogdanffy et al. (1994b)R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 76 TABLE 4.1.2.6 B Summary of statistically significan t non-neoplastic changes in lungs and nose of mice: main study

Incidence of Lesions Other than Tumors a
Males Females Concentration (ppm): Control 50 200 600 Control 50 20 0 600 Lungs: (51) (51) (56) (53) (56) (55) (55) (51)
Accumulation of alveolar macrophages very slight

slight moderate

severe 5 10 0
1 1 2 *
4
1 4
4 8 **

4 3
7
4 0 5 3
2
1 2 8
1 3 6
4
1
1 1 10 12 **

1 Intra-alveolar eosinophilic material very slight

slight moderate

severe 0 3 0 0 0
1 0 0 3
1 0 0 1 19 *** 10 **

2 0 0 0 0 0 0 0 0 2 0
1 0 1 7 ** 15 ***
1Accumulation of brown pigmented macrophages very slight

slight moderate 2 0 0 2 0 0 1
5
1 11 * 12 ***
1 3
1 0 5
1 0 1
4 0 2 21 ***
2 Intraluminal fibroepithelial projections very slight

slight moderate 0 0 0 1 0 0 2 0 0 3 17 ***

3 1 0 0 0
2 0 0
1 0 6 19 *** 7 ** Bronchial gland dilatation 14 16 26 17 8 17 20 * 15 Bronchial/bronchiolar epithelial

flattening and/or exfoliation very slight

slight moderate

severe 0
1 0 0 0 0 0 0 0 0 0 0 4 25 ***

7 *
0 0 0 0 0 0 0 0 0 0 0 0 0 4 * 28 ***

4 *

1 Bronchial/bronchiolar epithelial disorganisation very slight

slight moderate 0 0 0 0 0 0 0 0 0 0 11 **

4 0 0 0 0
1 0 0 0 0 5 * 18 ***

0

a Figures in parenthesis present the numbe r of animals from which this tissue was examined microscopically. Significance of differences in a pairwise (Fisher ́s) test between each treatment and control incidence is indicated by * p < 0.05, ** p < 0.01, *** p < 0.001, cited from Bogdanffy et al. (1994b)R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 77 TABLE 4.1.2.6 B Summary of statistically significan t non-neoplastic changes in lungs and nose of mice: main study (Continued)

Incidence of Lesions Other than Tumors a
Males Females Concentration (ppm): Control 50 200 600 Control 50 20 0 600
Nose: (52) (48) (53) (50) (56) (57) (55) (51) Inflammatory exudate 0 0 2 15*** 0 0 1 5** Mucosal inflammatory infiltrate 1 0 0 12** 1 2 0 5 Submucosal gland hyperplasia slight moderate 3 0 3 0 28*** 8** 25*** 15*** 2 0 5 0 42*** 7** 35*** 13*** Olfactory epithelial atrophy

(mainly dorsal meatus) very slight

slight moderate

severe 0 0 0 0 0 0 0 0 2
5 28***

4 0 0
2 3 0
2 0 0 0
4 0 0 0 8 26***

4 0 0 0
1 Olfactory epithelial atrophy (widespread) slight moderate

severe 0
1 0 0 0 0 1 8*
4 0
5 39*** 0 0 0 0 0 0 0 12***

2 0 5* 45*** Squamous metaplasia at the naso/maxilloturbinate region very slight

slight moderate

severe 0
1 0 0 0
1
1 0 0
2 0 0 0 13** 11***

0 0
4 0 0 0
2 0 0 0 0 0 0 1 13* 6**

1 Replacement olfactory by

respiratory epithelium slight moderate

severe 0 0 0 0 0 0 5
1 0 11***
0 0 0 0
1 0
1 0 15*** 5*
0 10*** 10***

0
Trachea/bronchi : (49) (46) (51) (48) (55) (56) (52) (48) Epithelial hyperplasia 0 0 2 19*** 1 1 0 11***

a Figures in parenthesis present the numbe r of animals from which this tissue was examined microscopically. Significance of differences in a pairwise (Fisher ́s) test between each treatment and control incidence is indicated by * p < 0.05, ** p < 0.01, *** p < 0.001, cited from Bogdanffy et al. (1994b)R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 78 Oral application

- In oral dose range-finding studi es, groups of 5 male and 5 female rats or mice (SpragueDawley, CD-1) received vinyl acetate in drinki ng water at concentrations of 0, 50, 200, 1000 or 5000 ppm (rats, equivalent to 5, 20, 100 or 500 mg/kg bw, calculated on an assumed water consumption of 10% of body weight) and 0, 50, 150, 1000 or 5000 ppm (mice, equivalent to 7.5, 22.5, 150, or 750 mg/kg bw, calculated on an assumed water consumption of 15% of body weight) for 4 weeks (Gale, 1979; no data on purity, frequency of dose solution preparation or an alytical concentrations). Vinyl acetate was analysed by the commercial supplier c ontaining 3 ppm acetic acid and 21 ppm acetaldehyde. The concentration of acetic aci d was confirmed after delivery and after study completion. Test solutions were daily prepared containing th e nominal vinyl acetate concentrations including a corrective over-formulation for losses within 24 hours. Formulations were analysed for vinyl acetate concentrations prior to the administration during the first days (rat, mouse) and at Day 29 (rat only) of th e treatment period and reanalysed for stability 24 hours later. During th e 4th week of treatment the dose level of 50 ppm was increased to 10000 ppm. No deaths occurred during the course of the study in any of the experimental groups. With the exception of one single female mouse at 5000 ppm female mice, which showed tremor a nd hypothermia, all animals remained healthy throughout the study. Reduction of body wei ght gain and water consumption was observed in rats, particularly in females, at ≥ 1000 ppm, in male rats at ≥ 5000 ppm and in male mice at 5000 ppm. Reduced water consum ption was also apparent in male mice treated at ≥ 1000 ppm and in female mice at 5000 ppm , the latter consumed less food than control females. Lower feed consumption in rats was confined to females treated at 10000 ppm. Data on mean body weight were not reported in the summary document available, the only quantitative data given was that re duction in feed consumption was 11% during the first 3 weeks of the study. Absolute and re lative liver weights in rats of both sexes and female mice were lower in all treated groups compared to the controls. There are data on liver histopathology from 4 male and 4 female rats of the control and 5000 ppm groups showing mild multifocal portal and intral obular hepatitis similar to those lesions commonly observed in rats of this age and st rain. No other organs were processed for microscopy and no laboratory examinations on clinical chemistry or hematology parameters were conducted. Thymus weights were reduced in male mice exposed to 5000 ppm. There was no evidence of any treatment-related gross abnormalities in organs. The results provided the basis for selection of a ppropriate dose levels for 13-week studies. The NOAEL for rats was 200 ppm (20 mg/kg bw) (b ased on reduced body weight gain at 1000 ppm) and in mice, the NOAEL was 1000 ppm (150 mg/kg bw) (based on tremor and, hypothermia in a single female mouse a nd reduced thymus weight at 5000 ppm). Reductions of water consumption and in body we ight may reflect bad palatability of the test solutions, the toxicological relevance re duced liver weights (in the absence of any corresponding morphological or laboratory abnormalities) is equivocal.

- In oral 13-week studies accepted as valid acco rding to the requirements of the directive 793/93/EEC, groups of 10 male and 10 female Sprague-Dawley rats and CD-1 mice were administered vinyl acetate in drinking wate r at concentrations of 0, 200, 1000 and 5000 ppm (calculated mean dose levels: male rats 31, 163, 684, female rats 36, 193, 810 mg/kg bw/d; male mice 11, 60, 285, female mice 10, 72, 281 mg/kg bw/d) (Gale, 1980a, 1980b). The test substance was 99.9% pure and contained 0.01% acetaldehyde, 0.005% acetic acid, and 0.4% water. There were no deat hs during the study and all animals appeared normal. A slight, non-significant degree of grow th retardation became prevalent in male rats of the high dose group the mean body weight of these animals was 8% lower than thatR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 79 of controls. The weekly water consumption of male and female rats at 5000 ppm was significantly lower than that of the contro ls. The overall water consumption was 23% and 25% lower than in control males and fe males. A less marked reduction in water consumption was transiently seen for mid dose male and female rats. No treatment-related effects were seen with respect to hemato logy, blood chemistry, organ weights, or histopathology. In conclusion, administration of vinyl acetate in the drinking water for 13 weeks at concentrations up to 5000 ppm produced no evidence of organ toxicity in rats and mice representing the NOAEL for both species.

- 90-day drinking water studies were conducted in rats and mice to determine whether repeated exposure to vinyl acetate correlates with tissue toxicity, measured primarily by cell proliferation in and histopathology of upper digestive tract tissues (DuPont, 2000, Valentine et al., 2002). Males only were used si nce they appeared to be slightly more susceptible to neoplasia than females in th e Japanese oral cancer study (Umeda et al., 2004a). Test solutions were prepared twi ce weekly, samples of the low and high dose solutions were analysed for concentrations, stability and pH value.
Five groups of 20 male CDF (F-344)/CrlBr ra ts were administered vinyl acetate in the drinking water for 92 days at concentr ations of 0, 1000, 5000, 10000, and 24000 ppm vinyl acetate (99.98%) (DuPont, 2000). Animals were weighed and individually observed for body weight development, water consump tion and clinical signs of toxicity on a weekly basis. On test days 1, 8, 29, and 92, 5 rats per group were prepared for evaluation of oral cavity cell proliferation usi ng pulsed 5-bromodeoxyuridine(BrdU) uptake techniques and histopathology of the upper digestive tract tissues (oral cavity, esophagus, forestomach, duodenum). Evaluations of the oral cavity for cell proliferation and histopathology were limited to level III (identi cal to level III of the oral cancer study by Umeda et al., 2004a) and level VI from high dose rats and controls.
Drinking water solutions were daily prepar ed. Vinyl acetate concentrations taken from solutions in drinking water bottles were stable within 10% of nominal concentrations for at least 4 days. The pH of test solutions decreased with increase of the vinyl acetate concentration and time, e.g., from 5.21 on day 0 to 3.74 by day 4 at 2400 ppm. At this concentration, spontaneous hydrolysis of te st compound led to an increase of the acetic acid concentration from 55 ppm at day 0 to 650 ppm by day 4.
No mortalities or clinical signs of toxicity were attributed to vinyl acetate administration. Rats in the 5000, 10000, and 24000 ppm group ha d significantly lower mean body weights (-8.8, -7.4, -6-1%) and mean body weight ga ins (-13.4, -11, -9.2%) during the study relative to controls. Rats in the 10000 and 24000 ppm group significantly lower mean daily food consumption (-6, -7.4%) compared to controls. Mean daily water consumption was consistently and significantly lower dur ing the study in rats administered water solutions containing 5000, 10000, and 24000 ppm vi nyl acetate (-28, -37, -40.3%). Based on the overall mean water consumption data, the mean daily intake of vinyl acetate in rats from the 1000, 5000, 10000, and 24000 ppm gr oups was 81, 350, 660, and 1400 mg/kg bw, respectively. No test substance-related gross lesions were observed in the oral mucosa, esophagus, or forestomach of rats at any exposure level. Compared to controls, no test-substance related microscopic lesions were observed in the oral mucosa of rats at 24000 ppm. In rats of this group, significant in creases in mean cell proliferation occurred in the upper jaw on days 29 and 92 and in the lower jaw on test days 1 and 29. Labelling indices were increased less than 2-fold above the appropriate controls for these groups and were considered to be of equivocal biological significance.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 80 A similar study was conducted in B6D2F1/C rlBr mice (BDF1) (20 males/group) that received same concentrations of vinyl acetate. Evaluations of the upper and lower jaws for cell proliferation and histopathology were in itially limited to level III and V from highdose and control mice. Subsequently, the lower jaw from the intermediate groups sacrificed at 92 days was additionally evaluated to determine a NOEL for cell proliferation.

All mice survived to their sc heduled termination without any clinical sign of treatmentrelated toxicity. No vinyl acetate induced e ffect on body weight was observed. At various intervals during the study, mice from all te st groups had significantly lower mean food consumption compared to controls. However for the period day 0-92 no significant difference was observed. The mean daily wate r was significantly lower in mice from all test groups at various intervals and for the pe riod day 0-92 (-23, -30.5, -31.4, -35%). The mean daily intake of vinyl acetate in mice from the 1000, 5000, 10000, and 24000 ppm groups was 250, 1200, 2300, and 5300 mg/kg bw. No test substance-related gross lesions were observed in the oral mucosa, esophagus, or forestomach of mice at any exposure level. Compared to controls, no test-substan ce related microscopic lesions were observed in the oral mucosa of mice at 24000 ppm. Signi ficant and dose-related increases in mean cell proliferation occurred in the lower jaw of mice from the 10000 and 24000 ppm groups but only at 92 days. The increases were approxi mately 2.4- to 3.4-fold above the control groups mean for the 10000 and 24000 groups, respectively. Based on the magnitude of the increases and the dose-related nature of the response, these increases were considered to be compound-related.
The author concluded that increases in cell proliferation in the lower jaw of mice qualitatively and quantitatively paralleled the tumor outcome data of the Japanese oral cancer study (Umeda et al., 2004a). The incide nce of oral cavity neoplastic lesions was higher in the lower jaw than the upper jaw in eith er rats or mice (these details were not yet submitted to the rapporteur) and the incidence of these oral cavity lesions was about 3- fold higher in mice compared to rats. It wa s reported to be unknown whether the increased sensitivity in the lower jaw is attributable to an innate difference in tissue responsiveness or due other phenomena, such as a gravity de pendent enhancement in tissue dose to vinyl acetate. The increases in cell proliferation al so paralleled the administered dose of vinyl acetate in rats (3- to 4-fold less on body weight basis) and mice.

- No treatment-related histopat hological findings were reported in a short communication on dose-range finding studies in rats and mice (no further data on strains, animals/sex/group, etc.) at concentra tions of 0, 600, 1500, 3800, 10000 or 24000 ppm vinyl acetate in the drinking water after 13 w eeks. Water consumption was affected at 24000 ppm (calculated on an assumed water cons umption of 10% in rats, resp. 15% in mice to be equivalent to 2400 mg/kg bw/d for rats, resp. 3600 mg/kg for mice) (Umeda et al., 2004a, main study reported in 4.1.2.8).R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 81 Other routes

- No information on prolonged vinyl acetate e xposure via other routes was available.

Human data:

- No human data are available.

Summary on repeated dose toxicity

- Inhalation exposure
No premature deaths were confined to prol onged vinyl acetate treatment up to the highest tested concentrations of 2000 ppm in the ra t and of 1000 ppm in mice. Rough haircoat and hunched posture was observed on rats and mice e xposed to vapour concentrations of 50 ppm and higher for 2 years (Bogdanffy et al., 1994b, Owen, 1988). Prolonged inhalation exposure of rodents to higher concentrations of vinyl acetate vapour induced clin ical signs of growth retardation, eye and nose irritation, hunched posture, rough fur, respiratory distress and reduced urine volume. A reduction of body weight gain observed in mice ≥ 200 ppm and in rats ≥ 600 ppm after exposure over 2 years may be a ssociated to non-specific toxicity of vinyl acetate. It was interpreted to be attributed to lower food and water consumption, but the 2- year study did not contain any data on the cons umption of water/food and the food efficiency. Reduced urine volume observed in rats at 600 ppm of the 2-year study (Bogdanffy et al., 1994b) were not accompanied by other morphologi cal or functional abnormalities. No clear toxic effect could be identified in pa renchyma outside the respiratory tract.
Main effects of vinyl acetate we re the local toxic effects on the upper and lower respiratory tract. Rats and mice exposed repeatedly dem onstrated degeneration, partly accompanied by regenerative/reparative processes and occasionally inflammation, hyper- and metaplasia of the surface lining epithelia of the nose. Lesions of the nasal cavity were found in the epithelium of the olfactory and respiratory regions bei ng more pronounced in the olfactory epithelium. Rats exposed to concentrations of 200 ppm or higher over a period of 2 years (Bodganffy et al., 1994b, Owen, 1988) developed degenerative le sions of the olfactory mucosa. In the respiratory epithelium of the nasal turbinates, le sions were evident in this species at 1000 ppm after 4 weeks of vinyl acetate i nhalation (Bogdanffy et al., 1997). At the end of the study, cell proliferative rates were significantly in creased in the olfactory epithelium at ≥ 600 ppm, but no response was seen in the respiratory epithe lium up to 1000 ppm. Mice exposed at 200 ppm for a period of 2 years showed degenerative le sions of the olfactory mucosa. Squamous metaplasia were noted in the respiratory mu cosa at a concentration of 600 ppm accompanied by prominent inflammatory infiltration (B ogdanffy et al., 1994b). Hyperplastic and metaplastic alterations of the larynx and trach ea together with epithelial desquamation and fibrotic reactions of the tracheal epithelium we re exclusively found in mice at a concentration of 600 ppm within 2 years (Bogdanffy et al., 1994b, Owen, 1988). Similar changes were found in the bronchial and bronchiolar airways of rats and of mice at this concentration and exposure duration. In addition histiocytic cell accumulation in the alveoli and interstitium of the lung was observed being possibly related to increased lung weights.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 82 - Oral administration
No specific organ toxicity was recorded after re peated oral administration with drinking water of vinyl acetate to rats and mice. A subc hronic 13-week study revealed a slight (nonsignificant) reduction of food consumption and gr owth retardation in male rats at 5000 ppm (calculated to correspond to 684 mg/kg bw/d) (Gale, 1980a, b) that was supposed to be related to the 23% reduction in water consumption. No evidence of organ toxicity was detected in rats and mice of all dose groups. Thus, the NOA EL for both species was estimated to be 5000 ppm. Elevated rates of cell proliferation in the mu cosa of the oral cavity was observed in mice exposed for 92 days to vinyl acetate concentrations of 10000 ppm (5300 mg/kg bw/d) and rats exposed to 24000 ppm (1400 mg/kg bw/d) (D uPont, 2000; Valentine et al., 2002). The NOAEC for the mitogenic response was 5000 ppm (1200 mg/kg bw/d) in the mouse study and 10000 ppm (6600 mg/kg bw/d) for the rat study.

No/Lowest-observed-effect concentrations/levels

- Inhalation exposure
The combined chronic toxicity and carcinogeni city study on Sprague-Dawley rats and CD-1 mice (Owen, 1988, Bogdanffy et al., 1994b) was sel ected for the derivation of effect levels.

For local effects on the respiratory tract:
2-year study/Sprague-Dawley rats and CD-1 mice/NOAEC local 50 ppm (Equivalent to 178.5 mg/m3)

For systemic toxic effects:
2 year study/CD 1 mice/NOAEC sys 50 ppm (equivalent to 178.5 mg/m3)R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 83 - Oral administration
The 90-day drinking water studies of Gale ( 1980a,b) were performed according to current testing guidelines and therefore were considered to represent the most reliable data with respect to oral repeated-dose toxicity.

90-day study/Sprague-Dawley rats and CD-1 mice/NOAEL 5000 ppm (Equivalent to 684 mg/kg bw/d for male rats, 810 mg/kg for female rats, 285 mg/kg bw/d in male mice, 281 mg/kg bw/d for female mice).

This value is well corresponding to the NOAEL from long-term studies (Section 4.1.2.8) which was 1000 ppm for Sprague-Dawley rats receiving drinking water for 2 years (Bogdanffy et al., 1994a, Shaw, 1988). The NOAEL of 5000 ppm observed in mice treated for 2 years were considered to be less reliable, because the study did not contain laboratory investigations (Maltoni et al., 1997).
The 5000 ppm vinyl acetate concentration in drinking water is proposed as a NOAEL for systemic effects (684 mg/kg bw/d for the rat, 281 mg/kg bw/d for the mouse) for quantitative calculations in the risk characterisation.

Classification
As lesions of the respiratory tract epithelia occurred at concentrations above the critical concentration values according to the Annex VI criteria, there is actually no need for classification and labelling with respect to repeated dose toxicity.

4.1.2.7 Mutagenicity

4.1.2.7.1 Studies in vitro

Studies in vitro: bacterial gene mutations
Vinyl acetate was negative in bacterial gene mutation assays with Salmonella typhimurium strains TA 98, TA 100, TA1535 and TA1537 (McCa nn et al., 1975) with and without rat liver S-9 activation. Vinyl acetate was also negativ e in bacterial gene mutation assays with Salmonella typhimurium strains TA 98, TA 100, TA 1535 and E. coli WP2 uvr/pKM 101 with and without metabolic activation (JETO C, 2004). Also a negative result was obtained with the strains TA 100 and TA1530 after meta bolising vinyl acetate with mouse liver S-9 mix and gas phase exposure of the bacteria up to 2% vinyl acetate (Bartsch et al., 1979).
Jung et al. (1992) described a collaborative st udy to evaluate Salmonella typhimurium TA 102 with three laboratories. Vinyl acetate was negative in all laboratories; experimental details areR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 84 available only for one lab (Hoechst, 1988). Here , vinyl acetate, diluted in ethanol, gave negative results in three tests for doses up to 5000 μg/plate with and without S-9 mix.
Vinyl acetate was also negative in several inves tigations for which no adequate descriptions are available: bacterial gene mutation test in various Salmonella strains (Florin et al., 1980; Lijinski and Andrews, 1980; Brams et al., 1987) a nd SOS-chromotest with E. coli (Brams et al., 1987).

In vitro tests: bacterial genotoxicity Concentration range Test system With S-9 mix Without S-9 mix Result Toxicity Remarks Reference

Salm. typh. TA98, TA100, TA1535, TA1537 yes yes neg no data rat liver S-9 mix; tested doses not clearly specified McCann et al., 1975

Salm. typh. TA100, TA1530 0.003%, gas phase neg total toxicity at 0.02% and higher doses mouse liver S-9 mix with and without cofactors Bartsch et al., 1979

Salm. typh. TA102 up to 5000 μg/plate up to 5000 μg/plate neg Jung et al., 1992

Salm. typh. TA98, TA100, TA1535, TA1537 no data no data neg no data screening paper without details Florin et al., 1980

Salm. typh. TA98, TA100, TA1535, TA1537, TAQ1538 up to 1000 ug/plate up to 1000 ug/plate neg no data screening paper without details; use of rat and hamster liver S-9 mix Lijinski and Andrews, 1980

Salm. typh. TA97, TA87, TA100 100 to 500 ug/ml 100 to 500 ug/ml neg no data screening paper without details Brams et al., 1987

Salm. typh. TA98, TA100, TA1535, TA1537
E. coli WP2 uvr/pKM 101 1.22- 5000 μg/plate 1.22- 5000 μg/plate neg no data only test result tables, original data in Japanese JETOC, 2004

E. coli PQ37 130 to 8600 ug/ml 130 to 8600 ug/ml neg no data screening paper without details Brams et al., 1987R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 85 Studies in vitro: chromosomal mutations, micronuclei, mouse lymphoma assay
Norppa et al. (1985) investigated the induc tion of chromosomal aberrations in human lymphocytes (whole blood cultures and isolated lymphocytes) after 48-h treatment with vinyl acetate without S-9 mix. Positive effects were obtained for doses of 0.2, 0.5 and 1 mmol/l (isolated lymphocytes) or 0.5 and 1 mmol/l (whole blood cultures). Extremely steep doseeffect relationships were observed; the maximu m effect was ca. 90% aberrant cells. Toxicity data were not given.
In a similar investigation by Jantunen et al. (1986), with 24-h treatment of human lymphocytes (isolated lymphocytes and whole blood cultures), dose-dependent positive effects were found for doses of 0.25 to 2.0 mmol/l. Moderate to strong cytotoxic effects were seen for doses of 0.5 mmol/l and higher (inhibiti on of mitotic activity). Mustonen et al. (1986) used vinyl acetate as positive control in a chromosomal aberration test with human lymphocytes; 0.5 mmol/l led to an aberration frequency of 17.1% (excluding gaps).

In an in vitro micronucleus test with human lymphocytes without S-9 mix (Mäki-Paakanen and Norppa, 1987), increased micronucleus freque ncies were obtained for doses of 0.25 and 1.0 mmol/l vinyl acetate with e ffects of 3.2% and 3.1% micronucleated cells (negative control, 0.9%). Data on toxicity were not given.
A mouse lymphoma assay was reported to be positive with and without S-9 mix (Kirby, 1983); however, a full report with detailed data is lacking. Vinyl acetate was tested in concentrations ranging, with S-9 mix, from 1.8 to 5 μl/ml and, without S-9 mix, from 1.9 to 4 μl/ml; the highest dose of 5 μl/ml corresponds to 4650 μg/ml or 54 mmol/l. With S-9 mix, induced mutant frequencies were 2.4- to 7.4- fold that of the concurrent negative control; relative total growths ranged from 10 to 62%. Wit hout S-9 mix, 5- to 10.3-fold increases in mutation frequencies were observed; relative to tal growths were between 5 and 26%. Further details on the investigation are not available. Therefore, the relationship between genotoxicity and cytotoxicity cannot be evaluated. Furtherm ore, it cannot be deduced whether the genetic effects were preferentially due to gene or chromosome mutations.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 86 In vitro tests: chromosomal mutations, micronuclei, mouse lymphoma assay

Concentration rangeTest system With S9 mix Without S-9 mix Result Toxicity Remarks Reference

chrom. ab. in human lymphocytes not done 0.1 to 1 mmol/l pos no data 48-h treatment; pos at 0.2, 0.5 and 1 mmol/l (isol. lymp.), or 0.5 and 1 mmol/m (whole blood);extremely steep doseeffect-relationship; max. eff. ca. 90% aberrant cells Norppa et al., 1985

chrom. ab. in human lymphocytes not done 0.125 to 2.0 mmol/l pos clear inhibition of mitotic activity at 0.5 mmol/l and higher 24-h treatment; pos at 0.25 to 2.0 mmol/l (isol. lymph. and whole blood); max. eff. >40% aberrant cells Jantunen et al., 1986

chrom. ab. in human lymphocytes not done 0.5 mmol/l pos no data vinyl acetate was used as positive control Mustonen et al., 1986

micronuclei in human lymphocytes not done 0.125 to 2.0 mmol/l pos no data 48-h treatment; pos for doses of 0.5 and 1.0 mmol/l; max. eff. 3.2% micronucleated cells (negative control, 0.9%) MäkiPaakanen and Norppa, 1987

mouse lymphoma assay 1.8 to 5 μl/ml 1.9 to 4 μl/ml pos with S-9 mix, total growth ranged from 10 to 62%; without S-9 mix, from 5 to 26 % full report lacking; no data on mutationfrequencies; no colonysizing Kirby, 1983

Studies in vitro: SCE
Vinyl acetate clearly induced sister-chromatid exchanges (SCE) in human lymphocytes in the absence of S-9 mix. According to Norppa et al. (1985) after 48-h treatment all tested doses ranging from 0.1 to 1 mmol/l were positive; the highest dos e led to an SCE frequency of 120 per cell. He and Lambert (1985) demonstrated that the SCE induction was dependent on the treatment time. With 1-h treatment doses in the mmol/l-range were needed for positive effects; this investigation suffers from the disadvantage of unusual high negative controls of ca. 20 SCE per cell.
SCE induction by vinyl acetate was al so demonstrated in CHO cells (Norppa et al., 1985). With 24- h treatment time without S-9 mix, effects were similar to those observed in human lymphocytes. After 4-h treatment effects were stronger in presence than in absence of S-9 mix.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 87 In vitro tests: SCE

Concentration rangeTest system With S9 mix Without S-9 mix Result Toxicity Remarks Reference

human lymphocytes not done 0.1 to 1 mmol/l pos strong inhibition of cell proliferation at high doses, but SCE induction not limited to doses with strong toxicity 48-h treatment; pos at all tested doses; extremely steep dose-effect relationship; max. SCE frequency ca. 120 per cell Norppa et al., 1985

CHO cells 0.2 to 2 mmol/l 0.1 to 5 mmol/l pos strong inhibition of cell proliferation at high doses, but SCE induction not limited to doses with strong toxicity 24-h treatment without S9 mix: strong pos effect at all tested doses; 4 h treatment: stronger effect with S-9 mix than without Norppa et al., 1985

human lymphocytes not done 0.1 to 2.4 mmol/l pos no data investigation of time- and dose-dependency: with 1-h treatment doses in the mmol/l-range needed for positive effects; extremely high negative controls of ca. 20 SCE per cell He and Lambert, 1985

Studies in vitro: DNA strand breaks
Induction of DNA strand breaks in human lymphocyt es by vinyl acetate was analysed using the alkaline elution technique by Lambert et al. (1985). 4-h treatment with concentrations of 10 and 20 mmol/l did not result in an increase of DNA strand breaks.

In vitro tests: DNA strand breaks Concentration range Test system With S-9 mix Without S9 mix Result Toxicity Remarks Reference

alkaline elution, human lymphocytes not done 10 and 20 mmol/l neg no data 4-h treatment Lambert et al., 1985

Studies in vitro: DNA-protein crosslinks (DPX)
Kuykendall and Bogdanffy (1992) demonstrated th e potential of vinyl acetate for induction of DNA-protein crosslinks (DPX) with purified plas mid DNA and calf thymus histone proteins. Doses ranging from 10 to 100 mmol/l were used. Induction of DPX was bound to the presence of rat liver microsomes.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 88 Induction of DPX was also found in isolated cells from rat nasal tissues (respiratory and olfactory; Kuykendall et al., 1993). With treatment times of 1 to 2 h, very high doses ranging from 25 to 75 mmol/l were needed for induction of DPX rates over the background level.
In the alkaline elution investigation of Lambert et al. (1985; see 'DNA strand breaks' above) the rate of X-ray induced DNA strand breaks was decreased by vinyl acetate which indicates the formation of DPX; vinyl acetate doses were 10 and 20 mmol/l.

In vitro tests: DNA-protein crosslinks

Concentration rangeTest system With S9 mix Without S-9 mix Result Toxicity Remarks Reference

DPX, isolated DNA + histone proteins 10 - 100 mmol/l 10 - 100 mmol/l pos use of rat livermicrosomes instead of S9 mix; pos only in presence of microsomes Kuykendall and Bogdanffy, 1992

DPX, cells from rat nasal tissues (respiratory and olfactory) 5 to 75 mmol/l pos totally toxic after 2- h exposure to 50 mmol/l 12- to 15-fold increase of DPX levels after 1-2 h exposure; LOEC 25 mmol/l Kuykendall et al., 1993

alkaline elution, human lymphocytes not done 10 and 20 mmol/l pos no data the induction of DNA strand breaks by X rays was decreased by treatment with vinyl acetate Lambert et al., 1985

4.1.2.7.2 Studies in vivo

Studies in vivo: micronuclei and chromosomal aberrations in bone marrow cells

A bone marrow micronucleus test with mice was done with single intraperitoneal administration of doses ranging from 250 to 2000 mg/kg; sampling was 30 h after treatment (Mäki-Paakanen and Norppa, 1987). Negative findings we re obtained for doses of 250 and 500 mg/kg. After treatment with 1000 and 2000 mg/kg vinyl acetat e weak increases in micronucleus frequencies were found: 1.33% and 1.57% micronucleated polychromatic erythr ocytes as compared to 0.6% in the negative control. However, these doses were in the highly t oxic range and were lethal to 6 out of 14 or 8 out of 14 treated animals. The ratio of polychromatic to normochromatic erythrocytes, which indicates local cytotoxicity in the bone marrow, was clearly depressed at these doses. The relevance of these findings is highly questionable.
Micronucleus frequencies were also determined w ithin 3-months toxicity studies with rats and mice. Bone marrow smears were analysed at the end of treatment and it was found that micronucleus frequencies in vinyl acetate treated animals were not signifi cantly different fromR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 89 control animals. Treatments of rats and mi ce were done via drinki ng water (1000, 5000 and 10000 ppm in drinking water; Gale, 1980a,b) or by inhalation (50, 200 and 1000 ppm; Owen, 1980a; 1980b). At the higher doses toxic effects were seen in all studies. All these investigations were done according to inadequate methodologies, e.g. the an alysed cell type was not specified and positive controls were lacking. Therefore, the findings are of low reliability.
In a publication without detailed description of the methodology, results of a chromosomal aberration test with male Wistar rats were reported (Nersesyan et al., 1990). Vinyl acetate was given via the i.p.-route, the only dose was 160 mg/kg which corresponds to 20% of the LD 50 ; sampling of bone marrow was done 26 h after treatment . From the 5 animals analysed, 8.2% of the cells carried chromosomal aberrations (negative control, 0.6%); gaps were included and the spectrum of induced aberrations was quite unusua l. A positive control was not included and coding of the slides was not mentioned. Altogether, this finding is of low reliability.

In vivo tests: micronuclei (MN) and chromosomal aberrations (CAb) in bone marrow

Test system Doses Exposure regimen Sample time Result Local cytotox General toxicity Remarks Reference

MN in

mouse bone

marrow 250 to 2000 mg/kg 1 x i.p. 30h pos 500 mg/kg and higher ca. 50% lethality at 1000 and 2000 mg/kg Mäki-Paakanen and Norppa, 1987

MN in rat bone

marrow 1000 to 5000 ppm over 3 months in drinking water neg no data no inappropr. methodology Gale, 1980a

MN in

mouse bone

marrow 1000 to 5000 ppm over 3 months in drinking water neg no data no inappropr. methodology Gale, 1980b

MN in rat bone

marrow 50 to 1000 ppm inhalation over 3 months neg no data no inappropr. methodology Owen, 1980a

MN in

mouse bone

marrow 50 to 1000 ppm inhalation over 3 months neg no data no inappropr. methodology Owen, 1980b

CAb in rat bone

marrow 160 mg/kg 1 x i.p. 26 h pos no data 20% of LD50 no detailed data Nersesyan et al., 1990

Studies in vivo: SCE in bone marrow cells
Vinyl acetate induced sister-chromatid exchanges (S CE) in bone marrow cells of male BDF rats (3 per group) after single intraperitoneal application (Takeshita et al., 1986). Weak effects were found at doses from 370 mg/kg upwards in non-hepatectomised rats and from 470 mg/kg upwards in hepatectomised rats. The maximum effect was ca. a doubling of the spontaneous SCE frequency atR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 90 560 mg/kg. The treatments were without clear infl uence on cell proliferation behaviour. Data on general toxicity were not given; it can be estim ated that 370 and 470 mg/kg correspond to half of the LD50.

In vivo tests: SCE bone marrow

Test system Doses Expos. regimen Sample times Result Local cytotox. General toxicity Reference

SCE, rat bone

marrow 370 to 560 mg/kg 1 x i.p. 21 h pos no no data Takeshita et al., 1986

Studies in vivo: DNA binding in rat liver
Binding to liver DNA was studied after administration of [ 14 C]-vinyl-labelled vinyl acetate to groups of 3 rats (male and female F344, male Wi star) (Simon et al., 1985b). The test substance was given orally (1mCi = 0.1 mmol per animal) or by inhalation (1200 to 1800 ppm). Four hours after start of exposure the livers were processed. Although radioactivity was measured in DNA and nucleoproteins, none of those DNA adducts were found which occur after exposure to analogue vinyl halides and vinyl carbamate

. The authors discussed that these findings should be viewed along with the rapid degradation of vinyl acetate to acetaldehyde and acetic acid by blood esterases. These intermediates may enter the metabolic C 2 -pool (via acetyl-CoA) giving rise to unspecific incorporation of the label into purine nucleotides.

In vivo tests: DNA binding

Test system Doses Expos. regimen Result Remarks Reference

DNA adducts, rat liver 1200 to 1800 ppm 4 h inhalation neg Simon et al., 1985b DNA adducts, rat liver 0.1 mmol / animal 1 x orally neg Simon et al., 1985b

Studies in vivo: germ cell effects
Micronucleus frequencies in early spermatids of mice were analysed by Lähdetie (1988) 13 days after a single i.p. administration of vinyl acetat e doses ranging from 250 to 1000 mg/kg. Doses of 750 and 1000 mg/kg were in the lethal range where 8 out 9 or 1 out of 4 animals died; group sizes were quite low (1 to 4 animals). No increase in micronucleus frequencies was seen.
Sperm abnormalities in mice were investigated 3 and 5 weeks after start of 5 daily i.p.-doses of 125 to 1000 mg/kg vinyl acetate (Lähdetie, 1988). At 1000 mg/kg no treated animal survived. At 750 mg/kg 1 out of 5 treated mice survived; the only su rviving mouse showed an increased frequency of abnormal sperms 5 weeks after treatment, but not 3 weeks after treatment.
All animals survived after i.p.- doses of 500, 250 and 125 mg/kg. Marked decreases in weight gain were reported for doses of 500 and 250 mg/kg.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 91 At 500 mg/kg increased frequencies of sperm anomalie s were detected in 2 of7 animals at 3 weeksampling (variation, ca. 2-14%) and in 4 out of 8 animals at 5 week-sampling (extremely high variation, ca. 1 to 62%). At 250 and 125 mg/kg no effects on sperm abnormality were observed.
Altogether, the effects on sperm abnormality were limited to doses in the highly toxic range. Furthermore, effects on sperm abnormality are not specific for mutagens but may be due to spermatotoxicity. Therefore, these findings are of low relevance for assessment of mutagenicity.

In vivo tests: germ cell effects

Test system Doses Expos. regimen Result General toxicity Remarks Reference

MN in early spermatids of mice 250 to 1000 mg/kg 1 x i.p., 13 days recovery neg lethality at 750 and 1000 mg/kg only 1 to 4 mice per group Lähdetie, 1988

sperm abnormality in mice 125 to 1000 mg/kg daily i.p. for 5 days pos lethality at 750 (4/5) and 1000 mg/kg (5/5) effects limited to doses with high toxicity and not specific to mutagenesis Lähdetie, 1988

Studies in vivo: Human studies - chromosomal aberrations
27 workers in the polyvinyl acetate production were analysed with respect to their frequencies of peripheral lymphocytes with chromosomal abe rrations (Shirinian and Arutyunyan, 1980). No exposure data were given. Aberration frequencie s varied from 2.2% (1976) to 2.5% (1977) and 2.4% (1978). In a negative control group of 20 workers from the non-chemical industry the aberration frequency was 1.0% in 1978 (not an alysed in 1976 and 1977). The negative control group was not 'matched', confounding factors were not considered. The authors do not claim a 'positive' result and no clear conclusion can be drawn.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 92 Human studies: chromosomal aberrations
Test system Exposure No. of subjects Matched negative control Authors concl. Genetic effect Reference

chromos. aberrations in peripheral lymphocytes not specified 27 no ? 2.2 to 2.5 % (1.0% in negative control) Shirinian and Arutyunyan (1980)

Genotoxicity of the acetaldehyde: possible contribution to vinyl acetate genotoxicity
Acetaldehyde is a metabolite of vinyl acetate through esterase-mediated metabolism. It is discussed that vinyl acetate exhibits its genotoxicity via acetaldehyde. For example Kuykendall and Bogdanffy (1992) demonstrated that vinyl acetat e induces DPX via acetaldehyde, and according to Norppa et al. (1985) chromosomal damage induced by vinyl acetate in mammalian cell cultures is through formation of acetaldehyde.

A comprehensive overview on the genotoxicity of acetaldehyde is given by the SCCNFP Opinion on acetaldehyde (2004). According to this overview acetaldehyde is not mutagenic to the standard battery of Salmonella typhimurium strains with a nd without metabolic activation. In a number of investigations with mammalian cells in vitro various genetic effects were induced. The genotoxicity of acetaldehyde was not dependent on the presence of external metabolisation systems. The lowest concentrations with positive genetic effects were in the ranges of 4.4 μg/ml for chromosomal aberrations and micronuclei and 1.3 μg/ml for SCE. With respect to other positive genetic effects, such as mutations in the mouse lymphoma assay, DNA binding and DNA strand breaks, higher lowest-observed-effect concentrations were repor ted. Doses of 4.4 and 1.3 μg/ml correspond to 0.1 and 0.03 mmol/l. In vivo, two investigations are available on the induction of micronuclei by acetaldehyde. In bone marrow cells of mice intraperitoneal administra tion of high acetaldehyde doses induced micronuclei (Morita et al., 1997). The lowest doses with observed effect were about 200 mg/kg in two independent investigations; this is approximately 50% of the LD 50 . In mouse spermatids no micronuclei were induced after single intraperit oneal administration of doses up to 500 mg/kg (Lähdetie, 1988). Acetaldehyde is a weak inducer of SCE in rodent bone marrow cells in Chinese hamsters (single intraperitoneal administration of 0.5 mg/kg; Korte et al., 1981) and mice (single intraperitoneal injections of 0.4 μg per animal [ca. 16 μg/kg]; Obe et al., 1979).

DNA-protein crosslinks (DPX) were induced in nasa l respiratory mucosa cells of Fischer 344 rats after inhalation exposure of 1000 or 3000 ppm (Lam et al. 1986). Similar ranges of DPX were produced following a single 6 h exposure and after 5 days of daily 6 hour inhalation period. Lower concentrations of 100 and 300 ppm were negative. Olfactory epithelium did not response at the end of a 6-hour exposure time at concentrations of 1000 and 3000 ppm, but exposure on 5 days resulted in a significant increase of DPX rates at 1000 ppm (no results on other test concentrations). The magnitude of response at 1000 ppm in vivo (DPX production of +12-13% at the end of 6 hour inhalation on 1 day or 5 days) was in the same range in homogenates of respiratory mucosa incubated with 100 mM acetaldehyde (DPX +14%).R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 93 Acetaldehyde is a naturally occurring substance in the metabolic pathways of animals and humans (metabolism of ethanol and sugars). It occurs in small quantities in human blood. Therefore, it may well be that acetaldehyde expresses its genotoxic potential in case of metabolic overload.

Genotoxicity of acetic acid: possible co ntribution to vinyl acetate genotoxicity
The vinyl acetate metabolite acetic acid is negative in bacterial genotoxicity tests (McCann et al., 1975; Hude et al., 1988; Zeiger et al., 1992).
Controversial findings were reported on in-vitro clastogenicity of acetic acid in CHL cells. According to Ishidate (1988; see also: Ishidate et al., 1984) acetic acid was negative for doses up to 1000 μg/ml (= 16.7 mmol/l) without S-9 mix. Morita et al. (1990) found pos itive effects with and without S-9 mix for doses of 12 and 14 mmol/l (721 and 842 μg/ml), a dose of 16 mmol/l (961 μg/ml) was totally toxic. Morita et al. (1990) c oncluded that acetic acid its elf was non-clastogenic, but the effect was due to, unspecific, decreased pH values.

In an in vitro SCE test acetic acid induced a marginal response at 5 and 10 mmol/l (Sipi et al., 1992). The maximum effect was a 1.5-fold increase a nd probably due to unspecific cell-cycle delay.
In a gene mutation test with transgenic mice a 2-fold increase in mutati on frequency was obtained after single dermal administration of 30 μg/kg ace tic acid (Myhr, 1991); a lower (12 μg/kg) as well as a higher dose (48 μg/kg) were without effect. In this early investigation on this test system no analysis of the mutation spectrum was done. Theref ore, it cannot be deduced from the test data whether the effect is due to mutations induced by acetic acid or due to the clonal growth of a cell carrying a mutation (an effect which is known for promoters).
Overall, the genotoxicity data on acetic acid give no relevant evidence that the genotoxic potential of vinyl acetate may be due to acetic acid.

Conclusion:

Vinyl acetate is negative in bacterial mutagenicity tests. In mammalian cell cultures various cytogenetic eff ects were induced in the absence of S-9 mix (chromosomal aberrations, micronuclei, SCE) and in the presence of S-9 mix (SCE; chromosomal aberrations and micronuclei not analysed with S- 9 mix). The lowest positive concentrations ranged from 0.1 to 0.2 mmol/l. A positive mouse lymphoma a ssay is in line with these results, but it cannot be deduced whether the positive effect is due to chromosomal or to gene mutations (no colony sizing). Mammalian cell culture investigati ons on DNA strand breaks (DSB) and DNA protein crosslinks (DPX) were negative (DSB), or extrem ely high concentrations were needed for positive effects (DPX). Very few reliable data are available on the in vi vo mutagenicity of vinyl acetate. A weak induction of micronuclei in mouse bone marrow cells was clear ly limited to intraperitoneal doses in the LD50 range (1000 and 2000 mg/kg bw). In rats no induc tion of micronuclei was observed in spermatids (screening assay with intraperitoneal doses up to 1000 mg/kg bw). Furthe r tests on induction of micronuclei or chromosomal aberrations were of too low reliability.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 94 Also in an SCE test with rats positive effects were weak and limited to high and probably highly toxic intraperitoneal doses (370 and 470 mg/kg bw). Such weak increases in SCE frequencies may well be induced by unspecific effects on the cell cycle. No specific DNA binding was observed in rat livers after inhalation or oral administration. Induction of sperm abnormalities in mice again was limited to doses in the toxic range. Furthermore, it is not specific for mutagens.
No clear conclusion can be drawn from a human study on the possible induction of chromosomal aberrations in workers exposed to vinyl acetate. Genotoxicity data on vinyl acetate metabolites are in line with the hypothesis that vinyl acetate genotoxicity is mediated by acetaldehyde

. The genotoxicity of acetalde hyde is possibly limited to an overloading of defence mechanisms. Altogether, vinyl acetate has a mutagenic poten tial, which is preferentially expressed as clastogenesis. The data on in vivo genotoxicity are difficult to interpret, since their majority is of low reliability, or the effects are not specific to mutagenicity. The most important effect, a weak induction of micronuclei in mouse bone marrow, is lim ited to intraperitoneal doses of high toxicity. Therefore, it is unlikely that the genotoxic potential of vinyl acetate is expressed in germ cells in man. However, genotoxic effects locally in directly exposed tissues (site of first contact) cannot be excluded; the occurrence and strength of the effect s will be dependent on the metabolic capacity of the directly exposed tissue. No classification of vinyl acetate in terms of germ cell mutagenicity is proposed.

4.1.2.8 Carcinogenicity

Animal data:
Inhalation exposure

- In a combined chronic toxicity and carcinoge nic study (Owen, 1988; Bogdanffy et al., 1994b) male and female Sprague-Dawley rats and CD-1 mice including 60 animals per sex per dose and three satellite groups of 10 of each species and sex for interim evaluation at week 53 and week 83 and recovery studies (70 weeks of exposure followed by 15/16 weeks of recovery) were exposed by inhalation to vinyl acetate vapour in concentrations of 0, 50, 200, and 600 ppm over a period of 2 years (6 hours/day, 5 days /week). Exposure-related tumor response was observed in the nasal cavity of rats only. Concomitant degenerative, hyperplastic and metaplastic changes of the respiratory tract are described in 4.1.2.6 (Tables 4.1.2.6.A + 4.1.2.6.B). A tumor response of other organs re lated to vinyl acetate treatment was not evident in rats and mice.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 95 TABLE 4.1.2.8.A Summary of Statistically Significan t Neoplastic Changes in Lungs and Nose of Rats by Vinyl acetate: Main Study

Incidence of Tumors (Numeric) a

Males Females

Concentration (ppm): Control 50 200 600 Control 0 200 600
Lungs: (58) (59) (60) (60) (60) (60) (60) (59) Well differentiated adenoma [B] 0 0 0 0 1 0 0 0

Nose: (59) (60) (59) (59) (60) (60) (60) (59) Inverted papilloma [B] 0 0 0 4 0 0 0 0 Squamous cell carcinom a [M] 0 0 0 2 0 0 0 4 Papilloma [B] 0 0 1 § 0 0 0 0 0 Carcinoma in situ [M] 0 0 0 1 0 0 0 0

Total benign tumors 0 0 1 4 0 0 0 0 Total malignant tumors 0 0 0 3 0 0 0 4

Total nasal tumors 0 0 1 7** 0 0 0 4

Larynx: (59) (60) (60) (60) (60) (60) (60) (59) Squamous ce ll carcinoma [M] 0 0 0 0 0 0 0 1

a Figures in parenthesis represent the number of animal s from which this tissue was examined microscopically.

[B] = benign, [M] = malignant. Significance of differences in a pairwise (Fisher’s) test between each treatment and control incidence is represented by ** (p<0.01). Cited from Bogdanffy et al. (1994b), § exophytic papilloma in the olfactory mucosa zone, confirmed by personal communication

A total of 11 nasal cavity tumors (Table 4.1.2. 8.A) classified as papilloma, squamous cell carcinoma, carcinoma in situ in olfactory regions , and papilloma and squamous cell carcinoma in respiratory or anterior non-olfactory regions (distr ibution see Table 4.1.2.8.B) were evident in 7 males (11.9%) and 4 females (6.7%) of the high dose rat group. In the intermediate dose groups a single tumor (benign papilloma of the olfactory re gion) was found in a male rat. In the larynx a squamous cell carcinoma was found in a high dose female. No tracheal or treatment-related lung tumor was observed. No respiratory tract tumor wa s seen in the control and low dose groups except a single adenoma of the lung in a control female.

Table 4.1.2.8.B Regional dist ribution of vinyl acetate-induced nasal tumors in ratsR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 96 Site of origin Tumor type

Olfactory region 2 inverted papillomas

1 exophytic papilloma §

1 squamous cell carcinoma

1 carcinoma in situ

Respiratory region 2 inverted papillomas

Cuboidal epithelium of zone B a 2 squamous cell carcinoma

unknown 3 squamous cell carcinoma

#Cited from Bogdanffy et al., 1994b, § in a male of the 200 ppm group

a Zone B is located within a cross section of the nose at the le vel of the nasolacrimal duct medial/ventral to the incisor tooth root

In mice, no treatment-related increased incidence of tumors was observed in the nose, larynx, trachea, lung, or other tissues of mice in th e main study and in the satellite groups. A single squamous cell carcinoma in a major lung br onchus of a high dose male and a single adenocarcinoma in the lung of a control male was noted.

Oral application

- The offspring of F o -animals which received vinyl acetate in drinking water from the time of gestation at target concentrations of 0, 200, 1000 and 5000 ppm were investigated in a chronic and carcinogenicity study (Bogdanffy et al., 1994a; Shaw, 1988). Vinyl acetate was administered to male and female Sprague Dawley rats (60 offspring/sex/dose of the main study and 10 offspring/sex/dose for interim sacrifices at week 52 and week 78) via drinking water in concentrations of 0, 200, 1000, and 5000 ppm (ave rage vinyl acetate consumption: 0, 10, 47, and 202 mg/kg/day in males, 0, 16, 76, 302 mg/kg/ day in females) over a period of 2 years. The test substance contained contaminants in concentrations of ≤ 11.5 ppm acetic acid and ≤ 71 ppm acetaldehyde, ≤ 389 ppm water, the test solution was prep ared daily. They were examined for clinical symptoms, body weight, food and water consumption, parameters of hematology, clinical chemistry and urinalysis, gross and microscopical abnormalities. Numerous organs were examined histopathologically, but no tissues from the oral cavity (except the tongue) were listed as protocol organs. Rats of the 1000 and 5000 ppm groups consumed less water and rats of the 5000 ppm groups had decreased food consumption. Mean body weight gain of 5000 ppm males was significantly reduced compared to controls during the first (-11%) and second years (-17%). Mean body weight gain of 5000 ppm females was depressed (-11%) only during the second year. No treatment-related effect was seen for the mortality rates, or the test parameters of hematology, clinical chemistry or urinalysis. There was no evidence of systemic target organ toxicity. Some organ weights (brain, kidney, heart, liver, spleen, adrenal, pituitary) were altered at ≥ 1000 ppm, but were not associated with hist opathological changes and were therefore considered to be related to lower body weight . The high concentration did not exceed the MTD since feed and water consumption can be attri buted to the lower body we ight gain. The authors concluded that there was no treatment-related oncogenic effect. Squamous carcinomas were seen in the oral cavity of two high dose males and additional single other oral cavity tumorsR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 97 were observed in treated animals (fibrosarc oma in one low and mid dose males each, an odontoma in a mid dose female, and a malignant schwannoma in a high dose female). In addition, a single sarcoma was found in the stom ach of a high dose male. All reported tumors (including those in control and treated animals, which were not reported here) were considered to be within normal rates and within the biologi cal variation of the strain and age of rat. Due to the reduced body weight gain at 5000 ppm, the NOAEL for nonneoplastic effects was 1000 ppm (47 mg/kg bw/d in male rats, 76 mg/kg bw/d in female rats).
For reason of possible target organs not being r outinely examined and the fact that dose-related and significantly increased tumor rates in this study were absent did not give sufficient proof that carcinogenic potential of vinyl acetate was negative. Even when oral cavity was not examined as a protocol organ, two squamous carcinomas were seen in high dose males. As squamous cell carcinomas were not seen in cont rol animals and rarely occur in historical control rats of this strain, it comes into questi on - due the rapporteur's opi nion - that this finding may be related to vinyl acetate administration. Assumption is supported by concordance with data from other oral cancer studies in rats a nd mice that reported squamous cell carcinomas in the oral cavity (Umeda et al., 2004a).

- The chronic toxicity study of Lijinsky and Reube r (1983) revealed equivocal results concerning higher incidences of tumors in animals after or al administration of vi nyl acetate. Groups of 20 male and female F344 rats received vinyl acet ate dissolved in drinking water at 1000 or 2500 ppm over a period of 100 weeks and were observe d up to 130 weeks. Three types of neoplasm appeared at higher incidences in the treated groups. These were neoplastic nodules in the liver (males 0/20, 3/20, 2/20; females 0/20, 0/20, 6/20, historical controls 3-9.1%), adenocarcinomas of the uterus (0/20, 1/20, 5/20; historical controls 0.8%-10.8%), C-cell adenomas and carcinomas of the thyroid (males 2/20, 2/20, 1/20; females: 1/20, 2/20, 6/20, historical controls: 5-7.6%). Data on historical controls were re ported from internal control animals and from literature. The study performance was inadequa te since the vinyl acetate solutions were prepared only once a week, which resulted in hydr olytic degradation. Bogdanffy et al. (1994a) reported a 6% to 14% degradation of vinyl acetat e in tap water after 1 day and 40% to 60% over a 7-day period. The group size was small comparing to test standards for carcinogenicity studies and only gross lesions were processed for histopathology.

- In contrast to this, a recent carcinogenicity study of the Japan Bioassay Research Center (Umeda et al., 2004a, Celanese, 1998) reported to be in conformity to OECD Guideline 453 indicated that higher tumor incidences were i nduced by oral treatment with vinyl acetate. Groups of 50 male and female F344/DuCrj rats received drinking water containing 0, 400, 2000, and 10000 ppm vinyl acetate (98%, major impurities: water, acetic acid (no data on ppm), and 5 ppm hydroquinone, test solution was prepared twice a week) for 104 weeks (equivalent analysed doses in mg/kg bw/d, at 400 ppm: 21 in males and 31 in females, 2000 ppm: 98 in males, 146 in females, 10000 ppm: 442 in males and 575 in females). Groups of 50 male and female Crj:BDF1 mice also received drinking water containing 0, 400, 2000, 10000 ppm vinyl acetate for 104 weeks (equivalent mean doses in mg/kg bw/d calculated from body weight and amount of water consumed: 400 ppm: 42 in males, 63 in females, 2000 ppm: 202 in males, 301 in females, 10000 ppm: 989 in males and 1418 in females).

- The concentrations prepared for each group varied in comparison to the se t concentration within a range of 81%-120.8% for the 400 ppm group, 89-102.7% for the 2000 ppm group, and 71.4- 112% for the 10000 ppm group in the rat study and for the mice, values ranged from 81-113.3% for the 400 ppm group, 88.4-118.4% for the 2000 ppm group, and 74.1-120% for the 10000 ppm group. The concentrations of vinyl acetate in the drinking water was measured with a gasR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 98 chromatograph and stability of vinyl acetate in the drinking water was also measured in the preparations around the time of administration of the animals over a four-day period. A comparison of the results was reported to confirm stability (no quantitative data available). During the study, the general condition of the animals was observed once daily, the body weight and food consumption were estimated once w eekly for the first 14 weeks, thereafter body weight was checked once per two weeks and f ood consumption once monthly. For the first 14 weeks water consumption was estimated twice a week and once per two week thereafter. Hematology and clinical chemistry examinations were performed in animals surviving until the time of scheduled necropsy during the 104 th week after a fasting pe riod of at least 18 hours. Urinalysis was done on fresh urine collected from the animals as su rviving until the last week of administration. At present, no summary tables or individual data are available on laboratory examination. All animals underwent necropsy at th e end of the study (week 97 for the rats, week 94 for the mice), organ weight was measured on scheduled sacrificed animals on brain, lung, liver, spleen, heart, kidney, adrenal, testis , ovary. During the study the body weight and food consumption were estimated once weekly for th e first two weeks, thereafter body weight was checked once per two weeks and food consumption once monthly. For the first two weeks water consumption was estimated twice a week, and once per two week thereafter. Hematology and clinical chemistry examinations and urinalysis were performed (no data on time). All animals underwent necropsy, organ weight was measured on scheduled sacrificed animals on brain, lung, liver, spleen, heart, kidney, adrenal, testis, ovary. Histopathology examination of all animals included 37 organs/tissues (including the na sal cavity and the oral cavity with sections on three different levels each on the maxilla and mandible).

- The vinyl acetate concentrations in the drinking water measured 4 d after the preparation were found to decrease to 72-80% of the initial concentrations for rats and 86-96% for mice. The acetic acid concentration and the pH measured 4 d after the preparation were 9.2 ppm and pH 4.0 for the 400 ppm vinyl acetate-formulated dr inking water, 47 ppm and pH 4.2 for the 2000 ppm water and 263 ppm and pH 3.6 for the 10000 ppm water at the end of the 4-day administration period.

- In the rat, no significant difference between the su rvival of the treated groups and that of the control group was observed in the males or fe males. A slight decrease in mean final body weight was observed in the high dose groups (-8% in males, -10% in females) compared to the control groups. As outlined in figures on body we ight development, the growth curve from week 1 by week 16 was similar for all treatme nt and control groups. In this group, water consumption was on average 82% for the male rats and 75% for the female rats of that of the control groups. No significant difference in food consumption was seen for male and female groups that received vinyl acetate compared to the control values. Hematology tests reveal elevated concentrations for haemoglobin and MCH in high dose female rats. Male rats of this group exhibited an elevated albumin/globulin ratio and decreased levels of total cholesterol, phospholipids and calcium. Urinalysis revealed lowe r urinary pH values in male rats of the 400 and 10000 ppm groups. At necropsy, mandibular nodules were noted in three high dose males and in 1 female in the 400 ppm group in the mandi bular region and in the maxillary region of 1 female of the 10000 ppm groups. A decrease in the actual weights of the kidneys and livers of male rats that received 10000 ppm. There were hi gher incidences of tumor rates in the oral cavity, esophagus, and stomach that were considered to be treatment-related (Table 4.1.2.8.C). In the oral cavity, increased numbers of squamous cell carcinomas were found in exposed groups of females (control: 0/50, 400 ppm : 1/50, 2000 ppm: 1/50, 10000 ppm: 3/50 with significance p<0.05 in the Peto test, not signifi cant in the Fischer’s exact test and Cochran Armitage test), a significantly increased incidence occurred in males (control, 400 ppm and 2000 ppm: 0/50, 10000 ppm: 5/50 with significance p< 0.01 in the Peto test and p<0.05 inR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 99 Fischer’s exact test and Cochran Armitage test ). Squamous cell carcinoma metastasis to the tongue was noted in 1 male of the 10000 ppm gr oup. Squamous cell papilloma was observed in 2/50 males in the 10000 ppm group (total tumor ra te in high dose males 14%). In this dose group, basal cell activation was also observed in 2/50 males and 1/50 females. Epithelial dysplasia was seen in 2/50 of the 10000 ppm fema les. Mapping of neoplastic and preneoplastic lesions in the rat oral cavity of the high dos e group showed that lesions were distributed throughout the cavity, but 4 of 8 carcinomas occu rred at level VI (mandibular region at the anterior edge of the lower molar teeth). Tumors or lesions presumed to be preneoplastic lesions of the esophagus and stomach were only evid ent at 10000 ppm. One female out of 50 had a squamous cell carcinoma of the esophagus. In 1/50 males and 1/50 females, oesophageal squamous cell hyperplasia was observed. In addition, basal cell activation was observed in 4/50 females. No stomach tumors were found, but basal cell activation occurred in 2/50 males and 5/50 females in the 10000 ppm group.
Peto test revealed an increasing trend in the occu rrence of interstitial cell tumors in the testes of males (control group: 42/50; 400 ppm gr oup: 40/50; 2000 ppm group: 44/50; 10000 ppm group: 47/50), and an increased trend in the occurrence of adenocarcinoma in the mammary glands of females (control group: 0/50; 400 ppm group: 0/50; 2000 ppm group: 0/50; 10000 ppm group: 3/50). Both tumor rates were within the range of historical control data of the testing centre (82-98% (mean 89.6%) for interstitia l cell tumors and 0-6% range (mean 2%) for mammary adenocarcinomas).
Comment: The selected doses in this rat study al beit there are very high in the top dose were not considered to exceed the MTD since no i ndication on non-specific or specific systemic organ toxicity could be identified. The sli ght decrease in final body weight and increased haemoglobin values in female rats were most likely attributable to the significantly reduced water consumption. Lower kidney and liver wei ghts might be reflective for lower body weight gain in high dose males, no lesions indicative for organ toxicity were reported. No indications for clinically observed cachexia were reported, and tumor masses in the oral cavity of 1 or 2 animals out of 50 animals/dose groups were not to assume to inte rfere with food uptake because of the low number of animals affect ed; as to be expected the mean group food consumption in the dose groups was comparable to control values.
The increased numbers of squamous cell tumors (malignant and benign) in the oral cavity of male and female rats of the high dose groups we re considered as treatment-related. In the context of increased incidences of squamous cell carcinomas of the oral cavity in high dose males and females together with the occurren ce of some benign tumors and preneoplastic lesions of this cell type at this dosage and unde r consideration of the fact that spontaneous tumors of this type and at this site are rare, the authors in agreement with the rapporteur also considered single squamous carcinomas at 400 a nd 2000 ppm likely to be associated to vinyl acetate treatment. The same can be assumed for all effects on the esophagus and stomach.

- In mice no significant difference between the surv ival of the treated groups and that of the control group was observed in the males or fe males. A decrease in final body weight was observed in the high dose groups after week 60 w ith lower final body weights by 30% in males, and by 18% in females (starting after week 80) compared to the control groups. As outlined in figures on body weight development, the growth curve from week 1 by week 12 was similar for all treatment and control groups. Decreased mean water consumption was noted in the males of the 10000 ppm group (-15%), and dose-related in all female dose groups (-24% in the 400 ppm group, -8% in the 2000 ppm group, -17% in th e 10000 ppm group, compared to control group values). There was no significant difference in food consumption between treated and controlR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 100 groups. Hematology examinations revealed incr eased counts of platelets, neutrophils and decreases in lymphocyte counts for high dose ma les and decreased MCHC for high dose female. In males of the 400 group and males and fema les of the 10000 ppm groups serum glucose was reduced. In the males of 10000 ppm group, increas ed albumin/globulin ratios, increased ALP activity, and decreased total cholesterol, trig lyceride and calcium levels were observed. Urinalysis in this group revealed decrease urinar y pH values and increased urinary protein, in females at this dose level increased urinary pr otein and ketone bodies were noted. Clinical observation revealed tumor masses in the oral cavity in 6 males and 6 females of the 10000 ppm groups, the first appearance was noted in periods between week 65-78 in males and week 92- 104 in females. At necropsy, mandibular nodes were seen in 3 male and 5 females, maxillary nodes occurred in 3 males and 1 female in the 10000 ppm groups. Decreases in absolute weights and increases of relative weights of several orga ns were seen in male and female mice in the high dose group and the author thought this to be due to decreased body weight. Tumors associated with the vinyl acetate treatment were observed in the oral cavity, esophagus, forestomach and larynx. In the 10000 ppm group, squamous cell carcinomas of the oral cavity occurred in 13/50 males and 15/49 females (both significant) and squamous cell papilloma occurred in 4/50 males and 34/49 females (total incidence of squamous cell tumors in males 32% and in females 37%), but no squamous cell tu mors were seen in the control and low dose groups. Only at 10000 ppm, epithelial dysplas ia was observed in 24/50 males and 17/49 females. From doses at 2000 ppm and higher, squamous cell hyperplasia was also observed in 2/50 males and 1/50 females at 2000 ppm, and in 13/50 males and 6/49 females at 10000 ppm. Basal cell activation was found in 1/50 males a nd females each at 2000 ppm and in 18/50 males and 17/49 females at 10000 ppm. More than 60% of the male mice and 35% of the female mice had two or more preneoplastic le sions at different sites of the oral cavity; their incidence was highest at level V of the mandibular region (at the middle point between lower incisor teeth and molar teeth). In the esophagus, there were squamous cell tumors consisting of carcinomas in 7/50 males and 1/49 females of the 10000 ppm group and of one single papilloma in a 2000 ppm female. In the 10000 ppm group, lesions of preneoplastic nature were epithelial dysplasia (2/50 males, 7/49 females, squamous cell hyperp lasia (2/50 males and 2/49 females), and basal cell activation (9/50 males and 15/49 females). In the forestomach, squamous cell carcinomas occurred in 7/50 males and 3/49 females of the high dose group in comparison to none in the control and other dose groups. Benign squamous cell papilloma was evident in 2/50 males and 1/49 females of this dose group. Males at 10000 ppm had epithelial dysplasia (1/50), squamous cell hyperplasia (3/50), and basal cell activation (1/50). Squamous cell hyperplasia occurred in 2/50 females at 400 ppm and 4/ 49 at 10000 ppm and basal cell activation was observed in 1/49 females at 10000 ppm. Furthermore, squamous cell carcinomas in the larynx were seen in 2/50 males at 10000 ppm, 1/50 females at 2000 ppm a nd 1/49 females at 10000 ppm. In this group, there also occurred epithelial dysplasia (2 /50 males and 3/49 females), squamous cell hyperplasia (1/50 males) and basal cell activati on (3/50 males and 6/49 females). The stomach tumors were reported to arise from the forestom ach in treated mice, for basal cell activation of the rat stomach no certain localisation was noted. No other tumor type at any other organ/tissue site increased in both studies. Metastasis of s quamous cell carcinomas in the oral cavity were found in the lungs and lymph nodes of two ma les and two females in the 10000 ppm group and in the salivary glands of another female of th is group. Squamous cell carcinoma metastases in the lungs with origin from the esophagus or st omach were also seen in two other males, squamous cell carcinoma in another female metastasised to the kidney, pancreas and lymph nodes. In the 10000 ppm groups, a total of 9 males and 7 females died of tumors in the above mentioned target organs such as oral cavity (6 males and 4 females), in the stomach (1 male and 2 females) or larynx (1 male and 1 female) and in the esophagus (1 male). The authors concluded that squamous cell tumors (maligna nt and benign) occurring in the oral cavity,R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 101 larynx, esophagus, and stomach of male and fema le mice were caused by the administration of vinyl acetate. Atrophy of the sa livary glands was noted in 6 males and 4 females in the 10000 ppm group which were afflicted with tumors on the mandible and was thought to be a secondary change to tumor growth.

- Comment: The observation that the high concen tration (10000 ppm) administered to the top dose group animals have caused a reduction in fi nal mean body weight might indicate that the MTD was exceeded. But, the following reasons s upport the view that the MTD was not reached: There was no significant difference in survival rates between dose and control groups, although relatively high numbers of animals died becau se of squamous cell tumors. Lower final body weight can be attributed to reduced water c onsumption. Growth curves seems to follow the curves of water consumption with a delay of some weeks. Both effects developed during the late phase of the study, reduction in water consumpti on began after week 60 (males) or 80 (females). The depressing effect of lower water consumption may be superimposed by the development of squamous cell tumors that resulted in a number of deaths. No indication on vinyl acetate-related systemic toxicity either as non-specific or orga n-specific adverse effects could be identified. Otherwise, if the MTD would be exceeded, toxic signs were also to be expected for the early phase of a study where the mg/kg/d doses were much higher than in aged animals. The rapporteur’s comment is in agreement with the c onclusion of the investigators that the MTD is not exceeded (Umeda et al., 2004b).

- The authors concluded from these 2-year carcinoge nicity studies in rats and mice that vinyl acetate given in drinking water caused squamous ce ll tumors in areas of the upper digestive tract with direct contact (predominantly in caudal a nd exterior regions of the mandible that were highly exposed) and squamous cell hyperplasia, basal cell activation and epithelial dysplasia represented early stages of squamous cell tumo rs. The lowest concentration associated with squamous cell tumors was 400 ppm in female rats and 2000 ppm in female mice. This is in line with the dose-related increases of tumor inciden ces at 31 mg/kg/d and 61 mg/kg/d, respectively, calculated as dose/bodyweight. A BMDL10 of 477 mg /kg/d for the combined incidences of squamous cell carcinomas and papillomas in the oral cavity of rats and mice (both species and both sexes combined for calculation) was estim ated (BMDS version 1.3.1, US EPA’s NCEA, multistage model).R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 102 Table 4.1.2.8.C: Percentages of tumors a nd presumed preneoplastic le sions in a two-year carcin ogenesis study on F344 rats and BDF1 mice with drinking water administra tion of vinyl acetate ( Umeda et al., 2004a)

RAT 10000 ppm 2000 ppm 400 ppm control organ Tumor type/preneoplasia m# f m f M f m f oral cavity squamous cell carcinoma 10.0 * ↑ 6.0 ↑
- 2.0 ↑
- 2.0 ↑
- - squamous cell papilloma 4.0 - - - - - - -

basal cell activation 4.0 2.0 - - - - - - epithelia dysplasia - 4.0 - - - - - - esophagus squamous cell carci noma - 2.0 - - - - - - squamous cell hyperplasia 2.0 2.0 - - - - - -

basal cell activation - 8.0 - - - - - -

stomach basal cell activation 4.0 10.0 - - - - - -

MOUSE 10000 ppm 2000 ppm 400 ppm control organ Tumor type/preneoplasia m f m f M f m f oral cavity squamous cell carcinoma 26.0 ** ↑↑ 30.6 ** ↑ ↑ - - - - - -

squamous cell papilloma 8.0 ↑↑ 6.0 ↑↑
- - - - - - squamous cell hyperplasia 26.0 12.2 4.0 2.0

basal cell activation 36.0 34.6 2.0 2.0 epithelial dysplasia 48.0 34.6 esophagus squamous cell carcinoma 14.0 * ↑↑ 2.0 - - - - - - squamous cell papilloma - - - 2.0 - - - - squamous cell hyperplasia 4.0 4.0 - - - - - -

basal cell activation 18.0 30.6 - - - - - - epithelial dysplasia 4.0 14.2 - - - - - - forestomach squamous cell carcinoma 14.0 * ↑↑ 6.1 ↑↑ - - - - 2.0 - squamous cell papilloma 4.0 2.0 - - - - - - squamous cell hyperplasia 6.0 8.1 - - - 4.0 - -

basal cell activation 2.0 2.0 - - - - - - epithelial dysplasia 2.0 - - - - - - - larynx squamous cell carcinoma 4.0 2.0 - 2.0 - - - - squamous cell hyperplasia 2.0 - - - - - - -

basal cell activation 6.0 12.2 - - - - - - epithelial dysplasia 4.0 6.0 - - - - - -

m males, f females, - no tumo r observed, #no of animals: 50 (except high-dose female mice: 49) statistical results only on tumors: sign. difference to controls * p<0.05, ** p<0.01 in Fisher’s exact test positive trend in Peto test or in Peto test and Cochran-Armitage test ↑ sign. increase p<0.05 ↑↑ sign. increase p<0.01R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 103 - Another recent lifetime study on the carcinogenicity of vinyl acetate by Maltoni et al. (1997) reported increased tumor rates in Swiss mice or ally treated with vinyl acetate. The study was started in the 80’s and the study design did not show conformity with the current guidelines for cancer studies. Daily fresh prepar ed vinyl acetate solutions were administered in ad libitum supplied drinking water at 0, 1000 and 5000 ppm (cal culated to be equivalent to 0, 150, or 750 mg/kg bw/d based on a water consumption of 15% of body weight) for 78 weeks. Data on vinyl acetate purity and analytical concentration in th e drinking water and on water consumption were not given, but the test substance were reporte d to contain impurities of benzene (30-45 ppm), methyl and ethyl acetate (50 ppm), crotonald ehyde (6-16 ppm), acetaldehyde 2-11 ppm), and acetone (330-500 ppm). Male and female breeder s (13-14 males and 37 fe males/group) and of male and female offspring (37-39 males and 44- 48 females/group) were treated starting at 12th day of pregnancy. The animals were submitted daily to a clinical observation, the body weights were registered weekly within the first 13 week s and every two weeks thereafter until the end of treatment at week 78, and than every 8 weeks until the end of the study. The evidence of gross lesions was checked weekly for the first 13 weeks and thereafter every second week. All animals were necropsied and histopathology was performed on 28 organs/tissues and any other organ with macroscopic lesions. With respect of th e presumed target organs, five sections of the head were only included in animals treated longer than 100 weeks. Other target organs such as the tongue, esophagus, stomach, intestine were al so examined microscopically, but not the larynx. No treatment-related effect on the body wei ghts of male and female breeders and slight decreases in mean body weight in male and fe male offspring was seen. No treatment-related effect on survival rates occurred at the end of the study, the survival rates of the male and female offspring were slightly higher than cont rol animals. It was reported that no behavioural changes or non-neoplastic lesions were obs erved by gross inspection and histological examination. Higher incidence of tumors and presumed neoplastic lesions occurred in treated animals in the following organs (see Table 4. 1.2.8.D): Zymbal gland, oral cavity, tongue, esophagus, forestomach, glandular stomach, lung, liver, and uterus. The increase of stomach tumors was considered to be borderline increas e, higher rates of hepatocarcinomas were only seen among male offspring. The tumors of the lung, liver, uterus and Zymbal gland were not consistent with the findings of the Japanese study (Umeda et al., 2004a). Regarding relatively high spontaneous occurrence of tumors at these sites in the control groups of the study, the interpretation of these results is difficult. As the test substance contained impurities of known carcinogens (e.g. benzene, hydroquinone), the au thors assumed that these impurities were relevant for the tumor response. The rapporteur recognises the reduced reliability of this study due to impure test substance and the non-conc ordance with guideline testing procedures. However, this study showed some consistency w ith other studies. Compared to control animals that showed normal tissues (except some t ongue tumors) there were markedly increased incidences of squamous cell tumor and dysplas ia along the exposure route (oral cavity, tongue, esophagus, forestomach). For most effects on the epithelial surface of the upper digestive tract, the offspring were more sensitive than the parent animals. Tumors of this type at these sites were consistent to data from BDF1 mice in the study of Umeda et al. (2004a). The assumption of the authors is considered to be unlikely, as the concentrations of impurities were extremely low. Based on this study lacking laborator y investigations, the NOAEL for nonneoplastic lesions was 5000 ppm in mice (750 mg/kg bw/d).R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 104 Table 4.1.2.8.D: Percentages of tumors and presumed preneoplastic lesions in a lifetime carcinogenesis study in Swiss mice with drinking water administration of viny l acetate for 78 weeks (Maltoni et al., 1997)

group concentrations 5000 ppm 1000 ppm control breeders offspring breeders Offspring breeders offspring

organ tumor/preneoplastic lesion 13 m 37 f 49 m 48 f 13 m 37 f 37 m 44 f 14 m 37 f 38 m 48 f

Zymbal glands carcinoma - 2.7§ 4.1 8.3 - - - 4.5 - - - -

squamous cell dysplasia 7.7 16.2 8.2 22.9 - 8.1 - 4.5 - 2.7 5.3 6.3 oral cavity squamous cell carcinoma 7.7 2.7 20.4 18.8 - - - - - - - - tongue squamous cell carcinoma 7.7 8.1 14.3 25.0 - 2.7 - - - - 2.6 - squamous cell dysplasia - 8.1 8.2 14.6 - - - 2.3 - - - - esophagus squamous ce ll carcinoma - 16.2 24.5 37.5 - - - - - - - -

acanthoma - 2.7 - 6.3 - - - - - - - - squamous cell dysplasia 30.8 16.2 8.2 14.6 - - - - - - - - forestomach squamous cell carcinom a - 8.1 4.1 14.6 - - - - - - - -

acanthoma 7.7 13.5 16.3 22.9 - - 2.7 - - - - - squamous cell dysplasia - - 2.0 - - - - - - - - - glandular stomach adenocarcinoma 7.7 2.7 - 2.1 - - - - - - 2.6 -

adenomatous polyp - - - - - - 2.7 - - - - - glandular dysplasia - - 6.1 - - - - 2.3 - - - - lung adenocarcinoma 15.4 2.7 4.1 6.3 15.4 2.7 - 2.3 14.3 - 2.6 -

adenoma 23.1 16.2 22.4 22.9 15.4 16.2 16.2 6.8 14.3 8.1 15.8 12.5 animals bearing lung tumors 30.8 18.9 26.5 22.9 30.8 16.2 16.2 9.1 28.6 8.1 18.4 12.5

liver animals bearing hepatocarcinoma/s 15.4 - 34.7 4.2 30.7 - 21.6 - 21.4 - 26.3 2.1

uterus adenocarcinoma 16.2 16.7 5.4 13.6 2.7 10.4 leiomyosarcoma 5.4 8.3 - 4.5 2.7 - leiomyoma 5.4 12.5 - 6.8 2.7 4.2 total malignant uterus tumors 21.6 25.0 5.4 18.2 2.7 10.4

m males f females, - no tumor observed, § percentages, no statistical evaluation availableR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 105 - Vinyl acetate was administered in drinking wate r at doses of 0, 1000 and 5000 ppm to 17-week old Sprague-Dawley rats (breeders, 13 or 14 males/group and 37 females/group) and to 12-day embryos (offspring, 53-107 males/group and 57- 99 females/group) (Minardi et al., 2002). Treatment was continued for 104 weeks, thereafte r animals were kept receiving tap water until their spontaneous death. Vinyl acetate purity was > 99%, impurities were benzene 30-45 ppm, methyl and ethyl acetate 50 ppm, crotonald ehyde 6-16 ppm, acetaldehyde 2-11 ppm, and acetone 330-5000 ppm. In treatment groups, the ra tes of total malignancies and carcinomas and/or precursor lesions were increased in oral cavity, lips, tongue, oesophagus, and forestomach.

- It was reported that there were no differences between treated animals and controls in mean body weight, survival, behaviour, or treatment-re lated non-oncological pathological changes (no summary data included in the publication).

- Tumors of the oral cavity and lips occurred signi ficantly more frequent in offspring males and females (24.5% and 15.5%, respectively, versus 0% in the controls, Table 4.1.2.8.E) exposed to 5000 ppm concentration of vinyl acetate. No significan t effect was seen at the end of life in the rat groups (breeders), which were treated from the 17 th week onwards. Oral cavity squamous cell carcinomas were seen in two females (5.4%) of the 5000 ppm and in one female of the 1000 ppm (breeder) group. No significant tumor res ponse was seen at the tongue and the esophagus. Single females of the breeder group at 1000 a nd 5000 ppm and two females of the offspring group had squamous cell carcinomas of the tongue. However, squamous dysplasia was commonly observed in all treated groups of female s, their incidences were significantly higher in the 5000 ppm (breeders and offspring) compar ed to the controls. In the esophagus, only one squamous cell carcinoma was observed in a male offspring exposed to a concentration of 5000 ppm. In contrast, the incidences of squamous dys plasia were significantly higher in the breeder and offspring groups at 5000 ppm compared to th e control groups. Spontaneous dysplasia in the forestomach was seen in a number of control an imals of the breeders and the offsprings (3.7- 8.1%). Their rates increased significantly in offspring males and females at 1000 and 5000 ppm. (16.1% up to 24.6%). Squamous cell tumors at this site were significantly more frequent in the offspring males at 1000 and 5000 ppm and in the offspring females at 5000 ppm.

- In conclusion, treatment-related significantly increas ed rates of tumors were seen in the oral cavity and lips in the 5000 ppm offspring groups of both sexes and in the forestomach of the offspring groups of male rats at 1000 ppm and a bove and of female rats at 5000 ppm. Squamous dysplasia considered as precursor lesions were increased in theses groups and also in the breeder groups at 5000 ppm. Although the numbers of animals in the breeders group were limited, the animals of the offspring group at whic h the treatment started at day 12 of pregnancy appeared to be more sensitive towards tumor and precursor development.

- The study was not compliant to the current st andard for a carcinogenicity study. The major limitations were the reduced number of animals te sted in the breeders group, the variability of animal numbers among the test groups and the pr olongation of the post-treatment period until to the spontaneous deaths. Instead of a study termin ation animals were allowed to live until their spontaneous death and the tumor incidences were not corrected for the lifetime. No data on food and water consumption were available.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 106Table 4.1.2.8.E: Percentages of tumors and presumed preneoplastic lesions in a life-time carcinogenesis study in SpragueDawley rats with drinking water administration of vinyl acetate for 104 weeks (Minardi et al., 2002)

group concentrations 5000 ppm 1000 ppm control breeders offspring breeders Offspring breeders offspring

organ tumor/preneoplastic lesion 13 m 37 f 53 m 57 f 13 m 37 f 83 m 87 f 14 m 37 f 107 m 99 f

oral cavity squamous cell carcinoma 5.4 24.5** 15.8** - 2.7 - - - - - - squamous cell dysplasia 5.7 2.3 0.9 tongue squamous cell carcinoma - 2.7 1.9 3.5 - 2.7 - - - - - squamous cell dysplasia - 18.9* 5.7 15.8** § - 8.1 - 2.3 § - - - -

esophagus squamous cell carcinom a - - 1.9 - - - - - - - - - squamous cell dysplasia 15.4 21.6* § 35.8** 40.4** § 7.7 5.4§ - 4.6§ - 2.7 - -

forestomach squamous cell carcinoma 7.7 8.1 13.2** 7.0* 7.7 - 7.2* 3.4 - - - - squamous cell dysplasia 30.8 29.7* 24.5** § 24.6** § 23.1 5.4 19.3** § 16.1* § 7.1 8.1 3.7 4.0

*p<0.05, ** p<0.01 using χ 2test, § p<0.001 using Cochrane-Arm itage test for dose-response relationship

Other information after oral administration

- Newborn Wistar (4-5 animals per sex per group) rats were exposed orally to 100 or 200 mg/kg bw/d vinyl acetate (99% pure, impurity: 100 ppm hydroquinone) in condensed milk twice a day for three weeks. A subgroup of animals was add itionally treated with phenobarbital in drinking water for 8 weeks to stimulate the growth of potentially occurring preneoplastic liver foci. 14 weeks after the start of the study livers were dissected. No ATPase-free and gamma-GT-positive areas in the liver as indication for the devel opment of liver nodules could be found (Laib and Bolt, 1986).

Summary on carcinogenicity of vinyl acetate in experimental animals.
Vinyl acetate induced an increased number of nasa l tumors (mainly papillomas and squamous cell carcinomas) in various regions of the nasal mucosa of rats after long-term inhalation. The total incidence was significantly increased at a concen tration of 600 ppm, but a single papilloma already developed at 200 ppm. No significant tumor response was seen in mice after long-term inhalation of vinyl acetate vapour. Occasionally single squamous cell tumors occurred at other sites of the respiratory tract in rats and mice.
Although the complete report was not available, published information from a recent oral cancer study in F344 rats and BDF1 mice (Umeda et al. 2004a) demonstrated significantly increased rates of squamous cell tumors in the oral cavity (rats and mice), esophagus and forestomach (mice) after a 2-year administration of 10000 ppm vinyl acetate with the drinking water (equivalent mean doses in rats were 442 mg/kg bw/d for males, 575 mg/ kg bw/d for females, in mice 989 mg/kg bw/d for males, 1418 mg/kg bw/d for females). Maximum incr ease of tumor incidences was found in the oral cavity in both species. Squamous cell carcinomas were already observed at a dose of 400 ppm inR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 107 female rats (31 mg/kg bw/d). Consistently in another life-time study on a breeding and offspring generation of mice (Maltoni et al., 1997) which did not met actual standards on cancer bioassays, squamous cell tumors were also observed with increased incidences in several sites of the gastrointestinal tract (oral cavity, tongue, esopha gus, forestomach) at a concentration of 5000 ppm in the drinking water (calculated dose 780 mg/kg bw/d). In addition, higher incidences of adenocarcinomas of the glandular region of the stomach were found in high-dose male breeders. Also some other organs (lung, liver, uterus) showed increased rates of benign and malignant tumors compared to that of the control groups. Tumors of th e liver and the uterus have also been seen in the Lijinsky study (Lijinsky and Reuber, 1983). Howeve r, both studies hampered from methodical insufficiencies. Further, these data were inconsiste nt to the absence of parenchymal tumors in other more valid studies. Therefore interpretation of these tumors remains unclear. With respect to the carcinogenic potential of vinyl acetate, the results of Lijinsky and Reuber (1983) were considered not to be reliable due to several methodological deficiencies. No indication for an increased incidence of enzyme-altered liver foci was seen in another study (Laib and Bolt, 1986).
No clear positive tumor response was found in a nother oral rat cancer study at vinyl acetate concentrations up to 5000 ppm (Shaw, 1988, Bogdan ffy et al., 1994a). Except the tongue, tissues of the oral cavity were not included as standard pr otocol tissues for hist opathology. Although, this study showed the occurrence of tw o squamous cell carcinomas in the oral cavity of males of the 5000 ppm group.
Recently published data on rats exposed to drinking water containing 1000 or 5000 ppm vinyl acetate confirmed significant increases in squam ous cell carcinomas of the oral cavity and the forestomach (Minardi et al., 2002). Treatment of offsprings resulted in higher tumor rates than in rats with treatment begin at week 17 of life. Ho wever, this study has a number of limitations in its design. Thus, tumor response along the gastrointestinal could be interpreted to be supportive to the results from the Umeda study.

Human data:
Information on repeated human exposure to vinyl acetate is small. Quantitative data on exposure and effects were not well investigated or documen ted. Workers had also been exposed to other compounds, so that effects cannot be attributed clearly to vinyl acetate. Confounding factors (i.e. smoking habits) were not ruled out. Therefore the rele vance of the observed effects to evaluate risks to human health is questionable. Despite of thes e limitations some data from literature are cited below:

- A retrospective study on 21 chemical operators in a production plant with mean age of 45.3 years and mean exposure time of 15.2 years to vinyl acetate vapour with concentrations up to 49.3 ppm (TWA 5.2-8.2 ppm) revealed no vinyl acetate-related injury or differences in medical and biochemical parameters. Local irritant reacti ons were attributed to occasionally high acute exposures (Deese and Joyner, 1969).

- In a cohort study, 4806 male workers who were exposed to 19 different chemicals (vinyl chloride, polyvinylchloride dust, chlorinated solvents, acrylates, acrylonitrile and others) including vinyl acetate, between the years 1942 and 1973 had an excess risk of cancer of the respiratory system and the CNS. A subgroup (o f cases with lung cancer) with undifferentiated large cell lung cancer was associated to a slightly higher cumulative exposure to vinyl acetate (Waxweiler et al., 1981).R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 108 - A nested case-control study (Ott et al., 1989) was undertaken in a cohort of 29139 men employed in two chemical manufacturing facilities and a research and development center, whohad died in 1940-1978 with non-Hodgkin`s lymphoma, multiple myeloma, lymphocytic or nonlymphocytic leukemia. Exposure odds ratios (OR) were examined in relation to 111 work areas, 21 specific chemicals (OR based on an ever/nev er basis), and 52 chemical activity groups. Exposure to vinyl acetate was associated w ith non-Hodgkin’s lymphoma in seven of 52 men (OR 1.2), multiple myeloma in three of 20 men (OR 1.6), non-lymphocytic leukemia in two of 39 men (OR 0.5), and with lymphocytic leukemia in two of 18 men (OR 1.8). Examination of OR related to the exposure duration was not done because of the OR <1.3 or number of cases <4.

Summary of human data
Data on human experience were not specifically asso ciated to the exposure with vinyl acetate. In summary, the above-mentioned epidemiological data are insufficient to evaluate the carcinogenic potential of vinyl acetate in humans.

Other information from metabolites
Toxicity/carcinogenicity data from both metabolite s, acetaldehyde and acetic acid, were considered with respect to their possible role in vinyl acetate toxicity:
Acetaldehyde
With respect to the effects from external exposure to acetaldehyde the endogene level of acetaldehyde has to be taken into consideration:
Endogene acetaldehyde:
Acetaldehyde is a naturally occurring substance in the metabolic pathways of animals and humans (metabolism of ethanol and sugars). It occurs in low concentrations in human blood.
A range of 0.1 - 2.1 μM for pul monary blood acetaldehyde concentrations has been calculated in normal control subjects (Eriksson, 1987). The exact determination of the endogenous blood acetaldehyde level is impaired by the difficulty to exclude an artefactual acetaldehyde formation during the analytical procedures. Whole blood- associated acetaldehyde (WBAA) levels in teetotalers of 7.9 ± 0.7 μM (102 males) and 7.7 ± 0.6 μM (123 females) were measured by Halvorson et al. (1993). Acetaldehyde levels of 0.7 ± 0.5 μM in male human volunteers (n = 4) were obtained in the supernatants without precipitates from whole blood after headspace chromatography (Fukunaga et al., 1993).
In male Long-Evans rats treated with the al dehyde dehydrogenase inhibitors cyanamide and disulfiram endogenous blood concentrations of up to 2-5 μM were measured whereas no endogenous blood acetaldehyde could be detected in control animals (Eriksson, 1985). These results may indicate the existence of an endogenous acetaldehyde in protein bound forms.
Repeated dose effects following external exposure to acetaldehyde:R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 109 Inhalation exposure/animal data

- Although explant experiments on rat nasal turbina lia with olfactory or respiratory epithelium failed to demonstrate a cytotoxic potential of acetaldehyde at a concentration of 50 mmol on the olfactory and respiratory epithelia (Kuykendall et al., 1993), repeated dose studies demonstrated cytotoxic properties of acetaldehyde on the rat nasal epithelium.

- No histopathological abnormality was observed in the respiratory epithelium of rats (5 males/group), which were nose-only exposed to 750 ppm or 1500 ppm acetaldehyde on 3 consecutive days (6 h/d) (Cassee et al., 1996). In the olfactory region, a few necrotic cells were seen in 3/5 rats at 750 ppm, and 4/5 exposed to 1500 ppm showed cell necrosis (range few to many necrotic cells).

- In rats exposed to 0, 400, 1000, 2200 or 5000 ppm (790-9000 mg/m 3 ) acetaldehyde on 4 weeks (6 h/d, 5 d/w) treatment-related changes at 5000 ppm were dyspnoe, excitation during the first 30 min of each exposure, yellow-brown fur, severe growth retardation, more neutrophils and less lymphocytes in the blood, a reduced producti on of urine with a high density, increased lung weights, and severe degenerative, hyperplastic a nd metaplastic changes of the nasal, laryngeal and tracheal epithelium. The most severe lesi ons of the nose were found in the olfactory epithelium, but focal lesions were also observed especially in the posterior part of the nasal cavity covered with respiratory epithelium. Some minor alveolar alterations such as accumulation of pigment-laden macrophages and focally increased cellularity/thickening of alveolar septa were occasionally observed in the 5000 ppm group. Major lesions seen at 1000 and 2200 ppm (1800-3960 mg/m3) comprised growth retardation and an increased production of urine in males, slight to moderate degenerati on with or without hyper- and metaplasia of the olfactory epithelium, and only at 2200 ppm, mi nimal epithelial changes in the larynx and trachea. Focal degenerative lesions without hype rplasia were also observed single males and half of the females at 1000 and 2200 ppm of acet aldehyde. The only change observed at the 400 ppm level that could be attributed to acetaldehyde was slight degeneration of the nasal olfactory epithelium seen as loss of microvilli and thinning and disarrangement of the layer of epithelial cells (Appelman et al., 1982).

- A concentration without histopathological alterati ons on the respiratory tract was estimated to be 150 ppm (6 h/d, 5d/wk) in a 4-week inhalati on study on male Wistar rats (Appelman et al., 1986). Nasal lesions observed at 500 ppm were si milar as described for 400 ppm consisting of degeneration of the olfactory epithelium with a mean severity of slight to moderate.

- In a carcinogenicity study on rats exposed to 0, 750, 1500, 3000 (gradually reduced to 1000 ppm) ppm acetaldehyde vapour (6 h/d, 5 d/w) fo r up to 28 months treatment related-effects included increased mortality, growth retardati on, nasal tumors (Table 4.1.2.8.F), and nonneoplastic nasal changes in each of the test gr oups. At day 468, the mortality rate in the highdose group was 50% (28/55) for ma les and 42% (23/55) for females. By day 715, all high dose rats hat died and, at termination of the study at day 844, only a few animals were still alive in the mid-dose group. At the end of the study dose-related nasal changes comprised: degeneration, metaplasia and adenocarcinomas of the olfactory epithelium at all exposure levels. The respiratory epithelium showed squamous metaplasia and squamous cell carcinomas of the respiratory epithelium at the 2 highest e xposure levels, and slight to severe rhinitis and sinusitis in top-concentration rats (Table 4.1.2.8.G). In the larynx, hyperplasia and keratinised squamous metaplasia of the epithelium in the vo cal cord region were seen in many rats of the mid- and top-concentration groups. One fema le rat of the 1500 ppm group had developed a laryngeal carcinoma in situ (Woutersen et al., 1986).R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 110 TABLE 4.1.2.8.F Tumor incidence in the nasal cavity of rats exposed to acetaldehyde vapour for at most 28 months

Tumor incidences a
Site/type of tumor Males Females

control 750 1500 3000/

1000 control 750 1500 3000/

1000

Nose (49)# (52) (53) (49) (50) (48) (53) (53)

Papilloma 0 0 0 0 0 1 0 0

Squamous cell carcinoma 1 1 10* 15*** 0 0 5 17***

Carcinoma in situ 0 0 0 1 0 0 3 5

Adenocarcinoma 0 16*** 31*** 21*** 0 6* 26*** 21***

Larynx (50) (50) (55) (52) (53) (52) (54) (54)

Carcinoma in situ 0 0 0 0 0 1 0 0

a The number of animals examined is given in brackets.

Statistics: Fisher Exact Test *P<0.05 **P<0.012 ***P<0.001 # Number of tissues examined (Data from Woutersen et al. 1986)R059_0805_env_hhDraft of 29.05.2008CAS No.: 108-05-4111TABLE 4.1.2.8.G:Treatment-related non-neoplastic lesions inthe nasal cavity of rats exposed to acetaldehyde vapour for at most 28 monthsSite/type of lesionsMalesFemalescontrol 750 1500 3000/1000 control 750 1500 3000/1000Nose(49) (52) (53) (49) (50) (48) (53) (53)Respiratory epitheliumSquamous metaplasia without keratinisation 01 11**103 14***0Squamous metaplasia with keratinisation 0 05 19***01 16*** 18***Papillomatous hyperplasia 0 0 020 0 06*Simple/pseudoepitheliomatous hyperplasia 05 16*** 8**03 31*** 9**Olfactory epitheliumSquamous metaplasia withoutkeratinisation 0 0 0 0 0 01 1Squamous metaplasia with keratinisation 0 0 030 0 0 0Basal cell hyperplasia without atypia 037*** 9**0 042*** 19***0Basal cell hyperplasia with atypia 01 17***0 0 050Submucosal atypical basal cells 0 023***0 0 031*** 2Proliferation of glands inthe thickened submucosa 0 014*** 50418*** 5Larynx(50) (50) (51) (47) (51) (46) (47) (49)Squamous metaplasiawithout keratinisation2 2 10* 9* 106 9*Squamous metaplasiawith keratinisation1 4 13*** 32***03 17*** 23***Proliferation of dysplastic epithelium0 010 01 4 2Lungs(55) (54) (55) (52) (53) (52) (54) (54)Keratinised stratified squamous metaplasia of bronchial epithelium 0 0 010 0 0 0The number of animal examined is given in brackets.Statistics: Fisher exact Test*P<0.05 , **P<0.01 , ***P<0.001,Data from Woutersen et al. 1986R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 112 Lesions comparable to those seen after 28 months were observed in the acetaldehyde exposed rats of additional interim sacrifi ce groups killed at 13, 26 (subgroups of each 5 animals/sex/group) and 52 weeks (10 animals/ sex/group) after the same dose regimen as reported above (Wouterson et al., 1986) clearly demonstrating severe abnormalities in the nose and larynx, minor changes in the trach ea and nasal tumors (Woutersen et al. 1984). Of the animals killed at these intervals, onl y one had a tumor of the respiratory tract: a female in the high dose group killed in w eek 53, bearing a nasal squamous-cell carcinoma.

- Increased numbers of nasal tumors were also evident in rats which inhaled 750, 1500 or 3000/1000 ppm acetaldehyde vapour for 78 weeks as well as in rats exposed to acetaldehyde for 52 weeks followed by a recovery period of at most 26 weeks (Woutersen and Feron, 1987).

- Inhalative exposure of hamsters to 2500 ppm (4500 mg/m3) gradually decreased to 1650 ppm (2970 mg/m3) for a period of 52 weeks (7 h/d, 5 d/w) resulted in hyper- and metaplastic changes of the nasal epithelium, and hamsters developed nasal tumors (3/52) and laryngeal tumors (11/47) (Feron et al., 1982).

Oral administration/animal data

- A subacute oral toxicity st udy of acetaldehyde was carried out in Wistar-derived rats (Cpb:WU) (Til et al., 1988). Groups of ten male and female rats received drinking water containing 0, 25, 125 and 675 mg/kg bw/d acetal dehyde for a period of 4 weeks. Food and water intake was decreased in the top dos e groups. There was no significant effect on parameters of hematology, clinical chemistr y and urinalysis. The only adverse effect was slight to moderate hyperkeratosis of the stomach of high dose males and females.

- Soffritti and his colleagues (Soffritti et al., 2002) published the results of an oral carcinogenicity study that may correspond to the positive carcinogenicity bioassay that were announced by Maltoni et al. (1997). Acet aldehyde was administered to 50 male and 50 female Sprague-Dawley rats for 104 weeks in drinking water at concentrations of 0, 50, 250, 500, 1500, or 2500 mg/L. Increased rate s of tumors at several organs were observed in treated groups. However, the e ffects were not dose-related and no clear conclusion could be drawn from this study.

- In a study on cell proliferative activity, 20 Wistar rats were given either water containing acetaldehyde at a concentration of 120 mM ( 324 mg/kg/d) or tap water to drink for 8 months (Homann et al., 1997). Tissue specimens were taken from the tongue, epiglottis, and forestomach of each animal and imm unohistochemically stained for markers of cellular proliferation (Ki67 nuclear antigen) or differentiation (cytokeratins 1,4,10,11,14, and 19). The mean epithelial thickness of each sample was measured via light microscopy and differences between control and treated groups were analysed by use of unpaired Student’s t test. Although no tumors were observe d, staining for cytokeratins 4 and 14 revealed an enlarged basal layer of squam ous epithelia in the rats receiving acetaldehyde. In these animals, cell proliferation was signi ficantly greater than that observed in the control animals for samples from the t ongue (p<0.0001), epiglottis (p<0.001) andR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 113 forestomach (p<0.0001). In addition, the epith elia from acetaldehyde-treated rats were significantly thicker than in epithelia from control animals (p<0.05 for all three sites).
Oral uptake/human data
- Alcoholic consumption is a well-known risk factor for squamous cell cancer of the oropharynx, larynx and esophagus. Findings of consistence in the mutational spectrum induced by acetaldehyde in human lymphocytes and in the p53 tumor suppressor gene of oesophageal tumors were interpreted to s upport the assumption that tumors of the upper gastrointestinal tract are attributable to acetaldehyde which is the primary oxidation product of ethanol (Noori and Hou, 2001).
Other data relevant for acetaldehyde carcinogenicity
- In the recent evaluation on acetaldehyde given by the Scientific Committee on Cosmetic Products and Non-Food, (SCCNFP, 2004) data including additional human data from case were reported:
Acetaldehyde is a naturally occurring substance, also in human metabolic pathways. It is metabolised to acetic acid. Acetaldehyde itself is the main metabolite of ethanol and this reaction is catalysed by alcohol dehydr ogenases (ADH). Five ADHs have been characterized in humans, two of wh ich (ADH2 and ADH3), are known to be polymorphic. In particular, polymorphism for ADH3 seems to strongly influence the metabolism of ethanol to acetaldehyde, with ADH3 1 allele carriers being faster metabolisers than ADH3 2 carriers. Acetalde hyde is metabolised by phase II enzymes, including aldehyde dehydrogenases (ALDH) a nd glutathione S-transferases (GST). ALDH2 is polymorphic; its mutant allele, ALDH2 2, which leads to enzyme inactivity, is prevalent in Asian populations. GSTM1 is also polymorphic, with a null genotype GSTM1 0 present mainly in European popula tions (Coutelle et al., 1997). Therefore, carriers of ADH3 2, ALDH2 2 and GSTM1 0 alleles are likely to be exposed to higher levels of acetaldehyde than are other people, following intake of a comparable amount of alcohol. Supportive data were gained from testing in ALDH2-/- knockout mice in which a doubling of blood acetaldehyde concentrations and more severe toxicity was observed in comparison to wild-type (ALDH2+/+) mice (Isse et al., 2005).
An increased relative frequency of bronc hial and oral cavity tumours was found among nine cancer cases in one study of chemical workers exposed to various aldehydes. Three case–control studies assessed the risk of oral, pharyngeal, laryngeal and oesophageal cancer following heavy alcohol intake, according to genetic polymorphism of enzymes involved in the metabolism of ethanol to acetaldehyde (alcohol dehydrogenase 3) and inthe further metabolism of acetaldehyde (aldehyde dehydrogenase 2 and glutathione Stransferase M1). Despite limitations in the study design and the small size of most of the studies, these studies consistently showed an increased risk of alcohol related cancers among subjects with the genetic polymorphism s leading to higher internal doses of acetaldehyde following heavy alcohol intake as compared to subjects with other genetic polymorphisms.
Oesophageal tumours have been associated with genetically determined high metabolic levels of acetaldehyde after drinking alc ohol. A Japanese case–control study (Yokoyama et al., 1996) of ALDH2-related risk for oesophageal squamous-cell carcinoma in alcoholics (40 cases and 55 controls) and non-alcoholic drinkers (29 cases and 28R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 114 controls) during 1991–95 showed a higher risk fo r oesophageal cancer in those with one ALDH2 2 allele in both alcoholics (crude odds ratio, 7.6; 95% confidence interval (CI), 2.8–20.7) and non-alcoholic drinkers (odds ratio, 12.1; 95% CI, 3.4–42.8). Mantel– Haenszel adjustment for age and daily alc ohol consumption had virtually no influence on the risk estimates [adjusted odds ratios not given]. As persons who have the mutant ALDH2 2 allele have a high concentration of blood acetaldehyde after drinking alcohol, the results of this study were interpreted as strongly suggesting a carcinogenic role of acetaldehyde in humans.
The IARC has concluded that there is inadequate evidence in humans for the carcinogenicity of acetaldehyde and that ther e is sufficient evidence in experimental animals for the carcinogenicity of acetaldehyde.
The overall conclusion was that acetaldehyde is possible carcinogenic to humans (Group 2B).
In the EU, acetaldehyde is a carcinogen classi fied in EU as a Category 3 carcinogen and a Category 3 mutagen.

Acetic acid
Inhalation exposure/no repeated dose animal study with guideline equivalence is available.
The lowest concentration inducing histopathol ogical lesions in the nasal mucosa of mice exposed for 4, 9 or 14 days (6 h/d) was 55.4 ppm acetic acid (Zissu, 1995). Only the olfactory mucosa was affected.
A 4-hour nose-only inhalation of acetic acid at target concentrations of 600 μl/l or 1300 μl/l (0.6 or 1.3 ppm) followed by a 20 hour observation period resulted in very focal lesion in the respiratory epithelium of the dorsal meatur of le vel 1 of the nasal cavity in three out of five exposed rats (Kilgour et al., 2000). In vitro e xposure to 53.3 mM acetic acid, a concentration calculated to correspond to the in vivo air c oncentration, to olfactory and respiratory turbinates for 4 or 24 hour resulted in a significant reduction in ATP and potassium concentrations.

Discussion on vinyl acetate carcinogenesis
The manufacturing industry postulated a non-ge notoxic mode of action for vinyl acetateinduced carcinogenic effects being similar for th e respiratory tract and the gastrointestinal tract. The acceptance of this hypothesis will be discussed in the following part of this assessment report for each organ system as s uggested by the IPCS framework on cancer risk assessment subdivided into: postulated mode of ac tion, key events associated with hypothesis, dose-response relationship, temporal relationshi p, strength, consistency, specificity of association, biological plausibility and cohere nce, inconsistencies, uncertainties and data gaps, assessment of mode of action for tumors (according to the IPCS framework on cancer risk assessment, 1999).R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 115 I. Respiratory tract tumors:

Ia. Postulated mode of action
Bogdanffy and his co-workers postulated that vinyl acetate metabolism in the respiratory and olfactory epithelium of the nasal mucosa incr eases local concentration of intracellular H + and hence produced tissue acidification. This lowe red pH causes toxicity, atrophy, degeneration and subsequently reparative hyperplasia. The stimulation of hyperplastic activity for a significant time of the animal’s life span in creases the probability of mutation and tumor formation. This hypothesis emphasises the role of cytotoxicity with a minor contribution of the acetaldehyde as a mutagenic DNA-protein cro ss-linking agent. It was stated that ‘with sufficient genetic damage, induced by spont aneous mutation and acetaldehyde induced DNAprotein cross-links (DPX) olfactory degene ration progresses to a state of elevated proliferation and eventually, at high vinyl acet ate to neoplastic transformation’ (Bogdanffy and Plowchalk, 2001). Later on, the considera tions on the mode of action was slightly modified (Bogdanffy, 2002, Hinderliter et al ., 2005). Intracellular acidification was still thought to be the crucial step in a sequen ce of responses including acidification-induced mitogenic cellular proliferation of nasal re spiratory epithelium and acidification-induced cytotoxic cell proliferation in olfactory epithelium.
Ib. Key events associated with hypothesis
Step 1: From inhalation to cytotoxicity:

- Metabolic enzyme activities (Table 4.1.2.8.H and Table 4.1.2.8.I):
The enzymes responsible for the hydrolysis of vinyl acetate to acetic acid and acetaldehyde, and its further oxidation to acetic acid are carboxylesterase and aldehyde dehydrogenase (see 4.1.2.1). In principle, both were detected in th e respiratory and olfactory epithelium of the rat nasal cavity (Bogdanffy et al., 1986, 1987, 1998, 1999a).
Carboxylesterase
Earlier data on tissue homogenates and usi ng p-nitrophenyl butyrate to measure carboxyl esterase activity pointed to the fact that a higher sensitivity of the olfactory epithelium to toxic effects of vinyl acetate could be attributed to 6fold higher hydrolytic enzyme activity at this epithelium (Bogdanffy et al., 1987). These re sults were confirmed in tissue homogenates, where carboxylesterase-mediated hydrolysis of vinyl acetate was more efficient (4-7fold, related to protein content) in the olfactory epithelium than in the respiratory epithelium (Bogdanffy and Taylor, 1993). K m

was in the same low range in the olfactory and respiratory epithelium.
Data using an in vitro gas uptake method on organ explants from rat turbinates or sections of intact nasal tissue from humans demonstrated much lower esterase activity than seen in tissue homogenates. When the epithelial volume was cons idered into calculations, a similar esterase activity in both (olfactory and respiratory) regi ons was observed for the rat and a much higher activity was found for the respiratory epithelium for the human (Bogdanffy et al., 1998).R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 116 Data on carboxylesterase activity in human nasal tissues are sparse. Mainwaring et al. (2001) found that the ratio of carboxylesterase activity (methyl methacrylate as substrate) between olfactory and respiratory microsomes was simila r for the rat as well as for the man Esterase activity for both species was about 3fold higher in olfactory microsomes which is in line with a 2fold higher activity in olfactory microsom es reported by Bogdanffy et al. (1999a). In respiratory microsomes Mainwaring et al. (2001) estimated a 4fold higher activity for the rat than in the human samples. Th e activity in rat olfactory S9 mix (24fold) was much higher than in olfactory S9 mix from human orig in. Although there may be some carboxylesterases activity outside the microsomes, as demonstrated for liver cells, where carboxylesterase activity has also been identified in the cytoso l (Tabata et al., 2004), the low values for V in olfactory and respiratory microsomes or S9-m ix may indicate a lower hydrolytic activity in the human nasal tissues compared to those of the rat.

Table 4.1.2.8.H: Metabolic rate (V) for carboxylesterase activity (towards methyl methacrylate) in nasal tissues (adopted from Mainwaring et al., 2001)

Tissue V (nmol/min/mg protein)

Human Rat
Respiratory microsomes 2.7 a 14.3
Respiratory S9 0.15 a 3.5 a
Olfactory microsomes No data 38.6
Olfactory S9 0.48 a 12 a

Liver microsomes 494.0 a 46.6

a The values for rat S9 fractions and for all human tissues are for single rate measured at substrate concentration of 1.0 mM methyl methacrylate.

A more than 35fold higher activity of carboxyleste rase was also reported for rat nasal tissue homogenate (pooled from all regions, no region identified) compared to human respiratory epithelium from polyp tissue (which may not be representative for enzyme activity in normal tissue, expression is reduced in hyperplastic epith elium, see also Lewis et al., 1994) at similar enzyme affinity, when α -naphthyl butyrate was used as a substrate (Mattes and Mattes, 1992). While p-nitrophenyl butyrate was shown to be a competitive substrate of rat nasal α -naphthyl butyrate esterase, it did not affect human α -naphthyl butyrate esterase indicating that there are differences in substrate specificity of rat and human carboxyl esterases. Due to the limitations by tissue selection, this preliminary study c ould only be interpreted to support the rats’ significantly higher enzyme activity.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 117 Liver microsomal carboxylesterases are i nducible by exogenous compounds (Satoh and Hosokawa, 1995). Yet unknown, this could not be excluded for the nasal epithelial cells.
Aldehyde dehydrogenase
Specific aldehyde dehydrogenase activity is more than 2-fold higher in tissue homogenates from the respiratory mucosa than in homogena tes from the olfactory mucosa (Stanek and Morris, 1999). After adjustment to the cell vol ume the aldehyde dehydrogenase activity of the respiratory epithelial cells was threefold higher in rats than that of humans (Bogdanffy et al., 1998).
Two aldehyde dehydrogenases were identifie d in the rat nasal tissues: a high K m

isoenzyme, which was 5-8fold more efficient in the respirat ory mucosa than in the olfactory mucosa (not normalised to cell volume), and a low K m

isoenzyme of aldehyde dehydrogenase (with comparable low activity in both areas) (Casanova-Schmitz et al., 1984).

- Localisation of enzyme activity in various cell types of the upper respiratory tract:
Carboxylesterase
In the rats’ olfactory epithelium, carboxyleste rase was histochemically (Bogdanffy et al., 1987) and immunohistochemically (Lewis et al., 1994) most prominently localised in the Bowman’s glands, the ducts of the Bowman’s gla nd and in sustentacular cells of the olfactory epithelium, and it was absent in the basal ce lls, the neuronal sensory cells and the overlying mucus. The apical (supranuclear) and basal porti ons of the sustentacular cell cytoplasm were intensely immunoreactive for carboxylesterase (Olson et al., 1993). The exact subcellular location of carboxylesterase has not yet been id entified for nasal mucosa cells. In many other tissues, carboxylesterases from the mammalian multig ene family were mainly localised in the endoplasmatic reticulum (Potter et al., 1998, Satoh and Hosoka wa, 1995). A striking abundance of endoplasmatic reticulum in the supr anuclear area of the rat sustentacular cells where P450 enzymes are localised (Farbman, 1992) suggests that carboxylesterases may also be associated to the endoplasmatic reticulum in this type of cell (as in other tissues, Satoh and Hosokawa (1995)). Together with the abse nce of carboxylesterase enzyme activity in the neuronal cells this indicates that sustent acular cells are involved in the vinyl acetate metabolism.
At the respiratory epithelium various cell types of the epithelium (ciliated epithelial cells and cuboidal cells > nonciliated cells) demonstrated strong to moderate carboxylesterase activity by immunohistochemical staining. The goblet cells and the submucosal seromucous glands showed a negative or weak staining. Consiste nt with the low immunoreactivity, the overlying mucous was negative. Carboxylesterase activity of the basal cells of the respiratory epithelium was reported to be weak-moderate by Bogdanffy et al. ( 1987), and no or weak immunoreactivity was found by Lewi s et al. (1994) and Olson et al. (1993). No presence of carboxylesterase could be attributed to th e mucous by in situ immunostaining or by determination of activity in nasal lavage fluid: The Vmax value of nasal lavage carboxylesterase activity was 0.134 μmol/min/mg and 160times lower than that observed in nasal respiratory mucosal homogenates und far more lower than in the olfactory region (Bogdanffy et al., 1999a).
Similar to the rat, carboxylesterase immunoreactivity was diffuse in ciliated and secretory cells of the normal respiratory mucosa of the human, some subepithelial glands were alsoR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 118 positive (Lewis et al., 1994). Sections were fr om eight patients (7 females, 7 non-smokers) showing a large variation across samples fr om normal respiratory epithelium, local inflammation to hyperplasia and squam ous hyperplasia where carboxylesterase immunostaining was completely absent. Human data on carboxylesterase (immuno-) localisation in samples of the olfactory region were not available.
The observations on enzyme activity, distribution and cytosolic localisation in nasal mucosa cells does not support Bogdanffy’s assumption that carboxylesterase is bound to or embedded in the plasma membrane of the nasal epithe lium, and may act as a protective mechanism by removal of toxicants prior to the entry into the cell cy toplasm. With respect to the sustentacular cells, the main site of carboxyleste rase in the olfactory epithelium, there is no evidence of a secretory function for mammalian species (Farbman, 1992). As indicated by the absence of carboxylesterase in mucous, no hydroly tic cleavage occurs preliminary to the vinyl acetate uptake.
Aldehyde dehydrogenase
Immunohistochemically, aldehyde dehydrogenase wa s detected in the respiratory epithelium (ciliated epithelial cells>nonciliated epithelial cells>goblet cells>cuboidal cells), while the olfactory epithelium showed negligible immune-r eactivity (weak in the basal cell layer, weak to negligible reaction in Bowman’s glands, no immune-reactivity in sustentacular and sensory cells) (Bogdanffy et al., 1986). In addition, epithe lial cells of the trachea and ciliated cells of the lower bronchioles demonstrated little activity, which increased distally, and Clara cells of the lower bronchioles showed high activity of aldehyde dehydrogenase.
At the subcellular level aldehyde dehydrogenase is oenzymes are located in the cytosol and in the mitochondria. Intracellular distribution for aldehyde dehydrogenase for human nasal tissue is not known. There are at least two isoenzymes of aldehyde dehydrogenase, a high affinity mitochondrial aldehyde dehydrogenase-2 and an aldehyde dehydrogenase-1 in the cytosol. Polymorphism of isoenzymes wh ich impair enzyme activity and acetaldehyde metabolism are well known in subpopulations of As ian origin and may result in higher tissue concentration of a acetaldehyde after alcohol consumption (Ginsberg et al. 2002) .
The following Table 4.1.2.8.I summarises the ava ilable in situ immunohistochemistry data, in vitro data on tissue homogenates, and data on enzyme activity for the respiratory and olfactory epithelium in the rat and the man.
Overall, data from in-situ investigations using (immuno-)histochemistry methods and semiquantitative determination of staining intensity were consistent with the results from investigations on the enzyme activity of carboxylesterase and aldehyde dehydrogenase. The differences in epithelial thickness and the dilu tion effects by a contribution of non-epithelial cells in the cell homogenates may account for uncer tainties in the estimated absolute values for enzyme activity, especially for human tissu es. No (or few) data are available on the isoenzymes of carboxylesterases and aldehyde de hydrogenases in nasal tissues from the rat compared to those of the human.R059_0805_env_hhDraft of 29.05.2008CAS No.: 108-05-4119Table 4.1.2.8.I Data on enzyme localisation andactivity in the nasal mucosa of rat and manRespiratory epithelium(RE)Olfactory epithelium(OE)Remark ReferenceRat Man Rat ManCarboxylesteraseEnzyme activityin cell homogenatesVmax35.7 mg/hif normalised toepithelial volume:Vmax64 mg/hPrediction from gasuptake model:Vmax63 mg/hundetectable Vmax133.1 mg/hor normalised to epithelialvolume:Vmax39mg/hPrediction from gasuptake model:Vmax45.4 mg/hUndetectable, except for 1sample:478 nmol/min/mg proteinRat: Esterase activity in RE lessthan 2fold higher than in OE(Consider: related to tissue wetweight, no correction to proteincontent!)Uncertainty in estimation ofenzyme activity in human OEsample by 5time thickness ofhuman mucosa, dilution effect ofsubmucosal tissue and only onesample analysed.Activity in human sample was200times less than in rat OE(see also Bogdanffy andTaylor,1993)Bogdanffy etal. 1998Enzyme activity inmicrosomesor S9 mixVmax14.3 nmol/min/mgprotein3.5 nmol/min/mgproteinVmax2.7 nmol/min/mgprotein0.15 nmol/min/mgproteinVmax38.6 nmol/min/mg protein12 nmol/min/mg proteinVmaxNo data*0.48 nmol/min/mg protein(only one individual)Methyl methacrylate as substrate,at concentration of 1.0 mMCarboxylesterase activity 3foldhigher in OE than in RE*OE tissue gained not sufficientto prepare microsomal fractionsMainwaringet al., 2001R059_0805_env_hhDraft of 29.05.2008CAS No.: 108-05-4120Enzyme activity inmicrosomes23.8 μmol/min/mg/protein 41.4 μmol/min/mg/protein Activity higher in OE than in RE Bogdanffy etal., 1999aEnzyme activity incell homogenates+Vmax22-46 μmolacetaldehyde/min/mgproteinKm0.3-0.43 mM+++Vmax89-165 μmolacetaldehyde/min/mgproteinKm0.2-0.55 mMVinyl acetate as substrateEnzyme activity in OE was 4-7fold higher than in the REBogdanffyand Taylor,1993Enzyme activity incell homogenatesVmax0.1 μmol/min/mgproteinKm20.8±1.7 mM±SEVmax0.6 μmol/min/mgprotein34.4Km±3.9 mM±SEp-Nitrophenyl butyrate assubstrateEnzyme activity in OE was 6foldhigher than in REBogdanffy etal., 1987Immunohistochemistry Ciliated cells: +,Goblet cells:±Basal cells: -submucosal glands:±All ciliated andsecretory cells: +submucosalglandularepithelium: some +Bowman‘s glands/-ducts: +Sustentacular cells: +Basal cells: -Neuronal cells:−No data Lewis et al.,1984Immunohistochemistry Overall: +At cellular level:Mucous:−Ciliated cells, cuboidalcells: ++,nonciliated cells, basalcells +Goblet cells, submucosalseromucous glands:±Overall: +++At cellular level:Mucous:−Bowman‘s glands/-ducts:+++Sustentacular cells: ++Basal cells:±Neuronal cells:−Bogdanffy etal., 1987;R059_0805_env_hhDraft of 29.05.2008CAS No.: 108-05-4121Aldehyde dehydrogenaseEnzyme activity in tissuehomogenates64 nmol/min/mg protein 28 nmol/min/mg protein 60 mM acetaldehyde as asubstrateEnzyme activity 2fold higher inRE than in OEStanek andMorris, 1999Enzyme activity in cellhomogenatesVmax3.38 mg/hNo data Vmax0.94 mg/hNo dataRat: Enzyme activity 3fold lowerin OE than in REBogdanffy etal., 1998Enzyme activity High Kmisoenzyme: 128nmol/min/mg proteinlow Kmisoenzyme:0.8 nmol/min/mg proteinHigh Kmisoenzyme:28 nmol/min/mg proteinlow Kmisoenzyme:2.2 nmol/min/mg proteinHigh Kmisoenzyme 5-8timeshigher activity in RE than in OE,low Kmisoenzyme activitycomparably low in both epitheliaCasanovaSchmitz etal., 1984)Immunohistochemistry Ciliated cells +++nonciliated cells ++goblet cells +cuboidal cells:±Sustentacular cells:−Sensory cells:−Bowman’s glands:±Basal cells: +Overall negligible enzymeactivity in the olfactory mucosaBogdanffy etal., 1986R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 122 - Considerations on the role of enzymes:
Regarding that the olfactory region was more se nsible towards the cytotoxic effect and the tumor response (as indicated by the lower con centrations at which preneoplastic lesions occurred, 200 ppm, see Table 4.1.2.6.A), and the regional characteristics of the enzymes involved, the local concentration of acetaldehyde might be of critical value for the regional susceptibility for tumorigenicity.
Bogdanffy et al. (1998) considered the metabo lite acetic acid to be the initiator of cellular degeneration. Indeed, in vitro testing demons trated cytotoxic potential of acetic acid. 1 hexposure of rat nasal turbinate e xplants of respiratory and olfactory mucosa induced cytotoxic effects at 50 mM acetic acid (without a clear difference in susceptibility among olfactory and respiratory mucosa) (Kuykendall et al., 1993). Cyto toxicity was examined after 1 hr exposure to concentrations of 50 mM of test substances by enzyme leakage of acid phosphatase as into the media. No cytotoxic effect was obser ved on olfactory and respiratory mucosa by acetaldehyde, while a 3-fold enzyme release versus control levels by vinyl acetate (no difference among olfactory and respiratory epith elium), and a 4-fold release by acetic acid were seen. At equimolar concentrations , acetaldehyde demonstrated no potential for cytotoxicity and vinyl acetate was less cytotoxic than acetic acid. No significant difference in cytotoxicity was found between the olfactory a nd the respiratory epithelium. The absence of cytotoxicity in the acetaldehyde testing appear s not plausible (at least for the respiratory epithelium where the activity of aldehyde dehydr ogenase is high) assuming that acetic acid should rapidly be produced by aldehyde de hydrogenase activity. The nil response may indicate that either acetaldehyde did not reach the cytosol, no acetic acid was produced (e.g. by enzyme inactivity in the in vitro model) or that the produced acetic acid (which dissociates into acetate anions and protons) which were buffe red. No cytotoxic eff ect was observed at 25 mM vinyl acetate for incubation times up to 2 hours (no data for acetic acid). Using the transformation into the inhalation concentr ation as proposed by B ogdanffy (2002) 25 mM corresponds to about 100 ppm vinyl acetate (50 mM ≈ 200 ppm). Results of in-vitro tests could be interpreted to fit well for the lowest obs erved effect level for cytotoxicity in the area of the olfactory region, which was 200 ppm. Howe ver, in-vivo observations on the respiratory epithelium revealed cytotoxicity at 1000 ppm.
Assuming that acetic acid will be the main cytot oxic agent, the lack of cytotoxicity up to 600 ppm in the respiratory epithelium may indicate th at the local concentration of acetic acid in this area does not result in cellular damage. Thus the occurrence of tumors in this region (at 600 ppm) could not be attributed to acetic acid-related cytotoxicity.
For mechanistic considerations, the in situ distribution and activity of involved enzymes carboxylesterase and aldehyde dehydrogenase are of special interest. Both nasal regions, the respiratory and olfactory epithelium are capab le to metabolise vinyl acetate because the presence of both enzymes has been dem onstrated by immunostaining and activity measurements.
Regarding the different mucosal regions, the en zyme activity of carboxylesterase is higher in the olfactory region (4-7fold, related to protein content) compared to those of the respiratory region (Bogdanffy et al., 1999a, Bogdanffy and Ta ylor, 1993). This difference is consistent with the intensity of immunostaining in these regions (Olson et al., 1993).R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 123 Comparing the absolute capacities among the enzy mes, data indicated that the capacity of aldehyde dehydrogenase to aldehyde dehydroge nase is much lower than that for carboxylesterase to vinyl acetate in rat nasal ti ssues. In the olfactory epithelium, Vmax of aldehyde dehydrogenase was lower than the ac tivity of carboxylesterase (30-40fold lower towards their respective substances). The di fference is less marked for the respiratory epithelium, aldehyde dehydrogenase activity is 13-19fold lower than the carboxylesterase activity (Bogdanffy et al., 1998).

It is concluded that at the same local concentration of vinyl acetate above K m

of carboxylesterase, the intraepithelial concentrati on of acetaldehyde in the olfactory epithelium is expected to exceed that of cells in the resp iratory epithelium. Because of the differences in V max of aldehyde dehydrogenase as compared with carboxylesterase at concentrations above K

m

the oxidation (and thereby the detoxification) of acetaldehyde to acetic acid is limited and may result in intracellular accumulation of acetaldehyde. From the absence of aldehyde dehydrogenase activity in the sustentacular cells and sensory cells it may be assumed that acetaldehyde concentrations will be higher at the same external vinyl acetate concentration.
Compared to the olfactory epithelium, the lo wer carboxylesterase activity in the respiratory epithelium yielded a lower in situ production of acetic acid and acetaldehyde. This might be reflected by the higher LOAEC for cytotoxic effects (1000 ppm) and hyperplastic lesions (1000 ppm) in the respiratory epithelium than that for the olfactory epithelium (LOAEC 200 ppm for both effects, see Table 4.2.1.8.E).
Quantitative information on aldehyde dehydrogenase activities in the anterior (respiratory mucosa) and posterior (olfactory mucosa) nasal tissues of F344 rats is given in a paper by Stanek and Morris (1999). Activities averaged 210 and 160 nmol/min, respectively, corresponding to 64 and 28 nmol/min/mg protei n. Nasal uptake was measured at three inspired concentrations of 10, 300, and 1500 ppm acetaldehyde and resulted in an uptake efficiency of 54, 37, and 34% demonstrating a concentration dependence of uptake. Stanek and Morris (1999) elaborated convincing evidence that the underlying saturable process is the metabolism of acetaldehyde by aldehyde dehydroge nase. Capacity limitation for nasal ALDH is suggested to occur at inspired concentrations of 300 ppm or more.
Carboxylesterase localisation indicates intracellu lar metabolism of vinyl acetate in the above cited cell types, but did not explain why sel ective toxicity was evident in carboxylesterasenegative olfactory neuronal cells. Bogdanffy et al . (1998) concluded that the toxic effect was more likely a result from cell-specific sensitivity to cytotoxicity and to a lesser extent the function of metabolic capacity. The discrepancie s between cells with metabolic capacities and affected neuronal cells could suggest that add itional mechanisms are involved (e.g. selective sensitivity of cells, local distribution of metabo lic products). The latter has been discussed by Bogdanffy who assumed intercellular communicati on via tight junctions to play a role in transportation of acid metabolites from the sustentacular cells to the sensory cells, the most sensitive target cells of the olfactory mucosa (Bogdanffy, 1990). Indications on a potential of acetaldehyde to disrupt tight j unctions are available from a human colonic mucosa model (Basuroy et al., 2005). Indirect effects followi ng damage to the sustentacular cells could explain high vulnerability of neuronal (sensory) cells to vinyl acetate (as for many esters). These cells are adjacent to the sensory cells and have supporting functions. The toxic insult (here: by increase of tissue concentration of acetaldehyde and/or other metabolites) primarily damages the sustentacular cells, their dysfuncti on may initiate the neuronal cell death. Since no aldehyde dehydrogenase activity was localised in the sustentacular cell, the detoxificationR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 124 capacity through oxidation of acetaldehyde is l acking. This observation is in line with experience from other substances (e.g. met hyl bromide, Schwob et al., 1995) where the inhalation of a gas that needs metabolic transformation for toxification results in selective vulnerability of sustentacular cells and olfactory sensory neuronal cells whereas the basal cells are spared from toxic insult. Also, from others it was suspected in earlier studies that toxic metabolites might diffuse from cells of the Bowman’s glands (Olson et al. (1993).
For interspecies comparison, data on the ab solute enzyme capacities in rats and humans indicated that the capacity of aldehyde dehydrogenase is much lower than that for carboxylesterase, in rats and in human nasal ti ssues. In the olfactory epithelium, Vmax of aldehyde dehydrogenase was 30-40f old lower for the rat and 20fold for humans than the activity of carboxylesterase. The difference is less marked for the respiratory epithelium; aldehyde dehydrogenase activity is 13-19fold lowe r in rats and 5fold lower in humans than the carboxylesterase activity (Bogdanffy et al ., 1998). Taking these data into the account, there is no indication on a higher sensitivity of humans exposed to vinyl acetate compared to that observed in rats.

- Contribution of cellular acidification:
Due to the low activity of aldehyde dehydrogena ses in the olfactory region the metabolic oxidation of acetaldehyde and thereby additional generation of acetic acid is considered of minor importance for the olfactory region. Co mpared to the olfactory mucosa, the lower carboxylesterase activity and the relatively high activity of aldehyde dehydrogenase in the respiratory region is supposed to prevent the accumulation of acetaldehyde in this area by the oxidative pathway generating acetic acid. Howeve r, at higher vinyl acetate concentrations aldehyde dehydrogenase capacity may be exceeded and intracellular accumulation of acetaldehyde will occur.

It has been assumed that the intracellular production of acetic acid exceeds cellular buffering capacity and results in elevated H + concentrations which is thought to be associated with cytotoxicity (Plowchalk et al., 1996, 1997). The existence of intracellular acidification was supported by findings on cultured carboxylesterase-c ontaining hepatocytes exposed to various concentrations of a vinyl acetate-PBS soluti on (10-1000 μM). Dose-dependent reductions of intracellular pH values were observed at c oncentrations of 10-200 μM (expected mucous concentration resulting from inhalation expos ure to 50-670 ppm vinyl acetate), a marked decrease in intracellular pH appeared at 500 μM, no further drop occurred at 800 and 1000 μM. The maximal drop was 0.5-0.6 pH units. Th e reduction of intracellular pH was rapidly reversible within hepatocytes after wit hdrawal of vinyl acetate (Bogdanffy, 2002).
Uncertainty existed about the carboxylesterase activity of hepatocytes, which may differ significantly from those of the respiratory and olfactory mucosa cells. Earlier studies showed a hydrolysis rate about an order of magnitude higher in the rat liver than in the lung (no examination of nasal tissues) (Simon et al., 1985a). For the rat model, the carboxylesterase activity appears to be comparable in the liver and the olfactory microsomes and was nearly 3fold higher than in the respiratory epithe lium microsomes (Mainwaring et al., 2001). In contrast, human liver microsomal activity to wards methyl methacrylate is much higher (>100fold) than those of the olfactory and respiratory epithelium.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 125 Interestingly this model showed that no (acute ) cytotoxic effect was associated with the lowered pH-value up to the maximum reduc tion of 0.55 units at 500 μM and above (corresponding to inhaled concentrations above 1000 ppm). As cells returned to pre-treatment pH-values within 50 sec after treatment with 200 μM vinyl acetate, a high rate of proton efflux was thought to prevent from intracellula r proton accumulation. The assumption of the authors that the proton export is in the same range as its intracellular production appears to conflict to the proposal that acidification through acetic acid is - via cytotoxicity - the initial step in tumorigenesis. The lack of cytotoxic ity is in line with resistance of hepatocytes reported by Farkas and Tannenbaum (2005). A high concentration of 1000 μM vinyl acetate induced no secretion of protein and urea and some release of lactate dehydrogenase from hepatocytes that indicated 20 percent of cell death occurred at 24 hours after treatment.
Corresponding in-vivo data on the effect of vinyl acetate on intracellular pH of nasal mucosa cells were not available. In vitro exposure of isolated respiratory and olfactory epithelium cells to concentrations of 100-1000 μM vinyl acetate resulted in concentration-related decrease in intracellular pH in the respiratory epithelial cells (Lantz et al., 2003). A slight reduction in intracellular pH was seen at 100 μM, a plateau was reach ed at 500 μM and 1000 μM did not further increase th e acidification. The maximal decrease was –0.3 pH units (pH i 7.16 vs. resting pH i 7.49). In the olfactory epithelium, a bi modal distribution of pH values was observed. In contrast to the respiratory epithe lium cells, olfactory epithelial cells consisted of two populations with different behaviour. On ly one population responded dose-dependently to 100, 250, 500 and 1000 μM vinyl acetate treatment by reduction in intracellular pH. The maximum decrease in the responders was –0.3 pH units (peak pH i changed from 7.32 in control cells to 7.0 for the highest concentration) . Changes in pH values were reversible in all cells after washing.100 μM vinyl acetate di d not decrease pH when a carboxylesterase inhibitor (BNPP) inhibited carboxylesterase. Inte restingly, a plateau for maximal acidification was also reached for respiratory cells at 500 μM as in the liver cell model of Bogdanffy (2002). The lowest concentration tested (100 μM) already disturbed the intracellular proton homeostasis, but the overall extent of acidifica tion was rather low (-0.06 in the respiratory epithelium and – 0.03 in the olfactory epitheliu m). - Additional studies by Lantz et al. (2003) on explants from ethmoturbinates (olfactory) and maxilloturbinates (respiratory) using pHsensitive fluorescence imaging responses to vi nyl acetate observed only minimal acidification (-0.05 pH units) in the presence of 1000 μM vinyl acetate in the respiratory epithelial cells (peak pH i 7.4 in cells of control explant). Accordingly to the isolated cells, cells of the olfactory epithelium explant (peak pH i 7.4 in cells of control explant) responded by a bimodal distribution of cells with reductions of -0.2 a nd -0.8 pH units indica ting the presence of two different cell populations. In conclusion, the overall lower acidification of the respiratory epithelium appears to correspond to the lowe r carboxylesterase activity compared to the olfactory epithelium. However, the difference in responses produces uncertainty in the data reliability (e.g. -0.3 pH units in isolated respir atory cells and –0.05 pH units in the respiratory epithelial cells of the explant model). Responsive and non-responsive cell populations may reflect the differences in carboxylesterase activity among cell types of the olfactory epithelium (lack of enzyme in neuronal cells, neg ligible in basal cells, and marked activity in sustentacular cells and Bowman’s glands).
As acetic acid is responsible for intracellular acidi fication, the lack of further decrease in pH values above 500 μM in the above mentioned in vitro models indicates that the production of acetic acid is limited. The relevance of the minima l drop in pH (-0.2 pH units in hepatocytes, -0.2 pH units in respiratory ep ithelial cells, -0.14 pH units in olfactory epithelial (Bogdanffy, 2002, Lantz et al., 2003)) at tumor dose-equiva lent concentrations of 200 μM for cellR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 126 proliferative activity or tumor growth is questi onable. The lacking reactivity of hepatocytes at minor pH drops is in line with the observed tolerance of tracheal mucous epithelium to acidity. In tracheal tissue explants a reduction in ciliomotility, cell membrane destruction and intra- and intercellular oedema started in acidic environment at pH 6.70 and complete ciliostasis occurred below pH 4.9 (Holma et al., 1977).
Whether the predictions on carboxylesterase activ ity and intracellular acidification from the modelling in hepatocytes, nasal mucosa cells and explants are assignable in a quantitative manner to the in vivo situation of the human na sal targets remains uncertain. Considering the resistance to cytotoxicity and minor reductions in intracellular pH in hepatocytes exposed to up to 1000 μM vinyl acetate, which were consistent to the low extent of acidification and its reversibility observed in in-vitro single cell or turbinate explants of the respiratory and olfactory epithelium, the overall low aldehyde dehydrogenase activity in rat and human olfactory mucosa (which limits the additiona l production of acetic acid), and the lack of cytotoxicity up to 1000 ppm for the respiratory mu cosa, where tumors were already seen, lead to the conclusion that the contribution of intr acellular acidification as the presumed mode for tumor development is – if at all- only minor.
A validation study for the application of a human PBPK model with controlled human inhalation exposures to vinyl acetate showed that the human nasal model predicts the experimental observations with regard to vi nyl acetate and acetaldehyde in the airstream of human nasopharyngeal cavity in a concentration range from 1 to 10 ppm (Hinderliter et al., 2005).
Step 2: From cytotoxicity to cancer:
The degeneration and inflammation of the olfact ory epithelium observed in the toxicity and carcinogenicity studies after repeated/prolonge d inhalation exposure gave indication that cytotoxicity of target cells contributed to the tumor development in this nasal region. Concomitant lesions representing attempts to repair/regenerate the damaged olfactory epithelium were observed (Bogdanffy et al., 1994b). In the view that finally tumors occurred at this site, metaplastic and hyperplastic changes could be interpreted to represent the sequential steps in carcinogenesis. The olfact ory epithelium was more sensitive to develop degenerative lesions than the respiratory epithelium (Bogdanffy et al., 1997).
Early degenerative changes were evident in the sustentacular cells, but these cells primarily targeted by cytotoxic effects of vinyl acetate were not identical to the cell types of tumor origin. As no tumor of the neuro(esthesio-)b lastoma type were found in carcinogenicity studies on vinyl acetate, cells of tumor origin are more likely less differentiated cells with origin of the basal cell, intermediary cells of s quamous type or of the respiratory-cell like type rather than of the olfactory sensory cell type. Th e majority of tumors seen in the nose were of the squamous cell type indicating that cells of squamous metaplasia or surviving basal cells that undergo squamous cell differentiation were the tumor cell origin. Increased regenerative cell proliferative activity could trigger th e accumulation of cells with spontaneous DNA damage and thereby cause an increase in cancer . In addition, cells replacing the olfactory epithelium may have an altered susceptibility to noxious insults.
No data on carboxylesterase activity and aldehyde dehydrogenase activity are available for cells of hyperplasia and respiratory metaplasia in the olfactory epithelium. In human samples of hyperplastic tissue of the respiratory mucosa, a dramatic reduction in enzymeR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 127 immunostaining was found and enzyme was lacki ng in squamous metaplasia. The absence of activity fits well to the lack of carboxylesterase activity in the squam ous epithelium in the cranial portion of the nose (Olson et al., 1993). It might be assumed that the lack of carboxylesterase in hyperplastic/metaplastic re spiratory tissue protects against the vinyl acetate toxicity at this sub-site. However, chronic damage of the olfactory epithelium characteristically consists of a mixture of different epithelial/cell types (respiratory-like hyperplastic area, squamous metaplasia and dys plasia, atrophic/hypertrophic olfactory areas).

There remain uncertainties on the exact mechanis ms of the olfactory epithelium cell death and the disturbances in control of regenerating cell proliferation leading to carcinogenesis.
Ic. Dose-response relationship
Degenerative (atrophic) lesions of the olfactory mucosa were seen in rats at concentrations of 200 ppm or higher when exposed over 2 years (Bogdanffy et al., 1994b, Owen, 1988). In this species, the respiratory epithelium was less se nsitive to damage showing no lesions up to 600 ppm (Bogdanffy et al., 1994b), the lowest concentration with respiratory epithelial damage was 1000 ppm vinyl acetate after 4 weeks of i nhalation (Bogdanffy et al., 1997). Lesions of the lower parts of the respiratory tract (larynx, trachea, bronchi, bronchioli) were seen at 600 ppm vinyl acetate in rats.

A clear increase of nasal tumors at the olf actory, respiratory and other/unknown localisation occurred in rats at concentrations of 600 ppm. The total incidence of (all) nasal tumors was 11.9% in male rats and 6.8 % in female rats of the group (see Table 4.1.2.8.A).

Figure 4.1.2.8.A Nasal tumor precursors in the olfactory epithelium (OE) of rats ( Bogdanffy et al. 1994b)

0 20 40 60 80

0 ppm 50 ppm 200 ppm 600 ppm Vinyl acetate concentrationPercentage OE metaplasia

OE Basal cell hyperplasia OE atrophyR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 128 Figure 4.1.2.8.B

Regarding males and females at each dose group together (see above Figure 4.1.2.8.B), the incidence of tumors with site of origin in the olfactory region wa s 4% at 600 ppm (in 118 males and females). With respect to the olfact ory epithelium, toxic lesions occurred at lower concentrations (200 ppm) (see above Figure 4.1. 2.8.A) than those inducing an increase of tumor incidences (600 ppm). Dose-dependently the restorative basal cell proliferation increased in parallel to the degenerated (atrophic) olfactory epithelium. The dose-response curves for all effects assumed to be precurs ors of tumor development were non-linear, the NOAEC was 50 ppm. Olfactory epithelium metaplas ia was occasionally seen at 200 ppm (in 5/60 female rats, none in males). A single beni gn tumor was seen in the area with olfactory epithelium in a male rat at 200 ppm. As spontaneous tumors at this site are very rare, an association to vinyl acetate exposure could not be excluded. A significant increase in metaplastic lesions was evident at the clearly tumorigenic concentration of 600 ppm.

Figure 4.1.2.8.C Nasal tumors in the non-ol factory regions in rats No precursor lesions evident (Bogdanffy et al. 1994b)

0 2 4 6 8 10

0 ppm 50 ppm 200 ppm 600 ppm Vinyl acetate concentrationPercentage

non-OE Tumors Nasal tumors in the olfactory epithelium (OE) of rats ( Bogdanffy et al. 1994b)

0 2 4 6 8 10

0 ppm 50 ppm 200 ppm 600 ppm Vinyl acetate concentrationPercentage

OE TumorsR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 129 Tumors at other non-olfactory regions (tum ors of unknown origin were included here) occurred in 6% of male and female rats (7 out of a total of 118) (Figure 4.1.2.8.C). At the respiratory epithelium of the rat nose no cyto toxicity and no other precursor lesion was reported at 600 ppm, the concentration which i nduced tumors at this site after 2-year inhalation (Bogdanffy et al., 1994b). Toxic effects at this site occurred only at dose levels above those inducing tumors.
A dose-response relationship of degenerative (atr ophic) and other precursor effects (basal cell hyperplasia and metaplasia) and tumor development was identified for the olfactory region. No dose- response relationship was evident for cytotoxicity or other metaplastic changes could not be identified for the respiratory region.
Id. Temporal relationship
A temporal relationship of cytotoxicity-related tumor growth can be assumed for the tumors of the rat olfactory epithelium, because early de generative findings were seen in studies with 4-week duration (Bogdanffy et al., 1997). As no underlying toxic event could be identified in the respiratory epithelium of the rat nose at or below the tumor-inducing dose, a statement on the time progression is not possible.
No complete recovery of the olfactory atr ophy was observed in the recovery groups of the combined chronic and carcinogenicity studies on rats and mice (Owen 1988, Bogdanffy et al., 1994b). This is comparable to the recovery status known from acetaldehyde studies. A replacement of the damaged olfactory epithe lium by respiratory-like epithelium (without sensory cells) as well as regeneration with a less differentiated olfactory-like epithelium was reported (Woutersen and Feron, 1987).
Ie. Biological plausibility and coherence

From historical data it is known that nasal tumo rs have a very low spontaneous incidence in aging rats (St. Clair and Morgan, 1992, Brow n et al., 1991). Malignant nasal neoplasm were also rare in humans (overall rate <1/100 000; Lund, 1994).
The sequence of events (cytotoxicity, hyperplasi a, benign and malignant tumors) observed at the olfactory epithelium is consistent with the general knowledge on the tumor pathogenesis of substances for which genotoxicity could be excluded as mode of action. In case of vinyl acetate it has to be discussed whether acetalde hyde genotoxicity contributes to the sequence of events.
The evidence of tumors of squamous origin i ndicated that DNA damage occurred in cells of squamous metaplasia or in surviving basal cells that are precursor cells of squamous cell metaplasia or squamous cell tumors.
Vinyl acetate effects seem to coincide with acetaldehyde effects. Nasal tumors were observed after long term inhalation of vinyl acetate or acetaldehyde. In comparison with the vinyl acetate data mentioned above, the primary tumo r site after chronic acetaldehyde exposure of rats also was the nose, and tumors of the la rynx were occasionally observed in this species after chronic inhalation to each of the test substances. Except those nasal adenocarcinomas were not found in vinyl acetate cancer studies , tumor response from both substances was comparable at least for the rat. Whereas vinyl acetate was not tested in the hamster, the prevalent tumor site was the larynx, and onl y few tumors were seen in the nose ofR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 130 acetaldehyde exposed hamsters (Feron et al., 1982) . This indicates that these localisation do have the enzymatic capabilities; the difference in distribution was suspected to be due to species-specific differences in susceptibility of the epithelium to acetaldehyde, a difference in impact of acetaldehyde on the epithelium, a difference in breathing pattern, and/or a combination of all factors (Wouterson et al., 1984).
The nature of the effect - cytotoxicity – e voked by inhalation of acetaldehyde on nasal tissues seems to be comparable to that of vinyl acetat e. The rat respiratory epithelium was shown to be less sensitive towards toxic lesions than th e olfactory epithelium. (Wouterson et al., 1984, 1986, Appelman et al., 1982).
If. Inconsistency, uncertainties and data gaps
The presence of degenerative lesions at the ol factory epithelium demonstrates its specific sensitivity to cytotoxicity. The evidence of dose and temporal relationships and the evidence of sequential alterations (cytotoxicity, hyper- and metaplasia, benign and malignant tumors) support that cytotoxicity is associated to the tu mor development. This was seen in a long-term study on the rat, but was not consistent to the negative results from the mouse cancer study.

• Interspecies comparison to the mouse:
Degenerative lesions of the olfactory mucosa we re seen in mice at concentrations of 200 ppm or higher when exposed over 2 years. Treated mice showed lesions at the respiratory epithelium at 200 ppm after 2-year inhalation of vinyl acetate (Bogdanffy et al., 1994b, Owen, 1988). Lesions of the lower parts of the respirat ory tract (larynx, trachea, bronchi, bronchioli) were seen at ≥ 200 ppm vinyl acetate in mice.
In mice, it is noteworthy that toxic lesions be ginning at 200 ppm at both localisations of the nasal epithelia, but no nasal tumor occurred at concentrations tested up to 600 ppm. Reparative replacement of the olfactory ep ithelium by respiratory-like epithelium and squamous metaplasia as well as hyperplasia of the submucosal glands were similar to the effects seen in the rat, but no progression to tumo rs occurred in this target region. It can not be excluded that the single squamous cell carci noma of the lung bronchus was also associated to the vinyl acetate treatment occurring at the same concentration which induced epithelial exfoliation/disorganisation and fibrohyperplastic projections of the bronchus/bronchioles with high incidences (Bogdanffy et al., 1994b, Owen, 1988).
In mice vinyl acetate is also efficiently hydrol ysed in nasal mucosa. Since the values for carboxylesterase activities in the respiratory and olfactory regions were in the same range (olfactory: 0.4-0.5 μmol/min/mg protein in th e mouse compared to 0.6 μmol/min/mg protein in the rat, respiratory: 0.1-0.2 μmol/min/mg protein in the mouse compared to 0.1 μmol/min/mg protein in the rat, Bogdanffy et al. 1987) or were found at even higher ranges as in the rat (Bogdanffy and Taylor, 1993), a signi ficant tumor response in the nasal mucosa should be expected for the mouse. This raises questions on species-specific differences in the susceptibility of the nasal mucosa. Is the mouse nose less sensitive to tumor generation (consider the tumors of the gastrointestinal tract of the mouse)? Or does the mouse have a high activity of aldehyde dehydrogenase (in contra st to the low ALDH activity in rat olfactory mucosa) that effectively contributes to acetealdehyde elimination and thereby prevents in situ accumulation of acetaldehyde? Determination of aldehyde dehydrogenases activity revealed low Vmax in whole nasal tissue homogenates of mouse and hamster compared to ratsR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 131 (Morris, 1997). However, origin of epithelial material was not specified and whole tissue homogenates might be less predictive.
DNA adduct formation was observed in the rat nose, but no data were available for the nasal mucosa of the mouse. To explain the lack of nasal tumors in mice, further data are needed.
The mouse was negative for the inhalation route, but sensitive towards tumor development for the oral route (see 4.1.2.8).

• Uncertainties related to the role of intracellular acidification:
The role of pH changes remained unsolved for some critical points. In olfactory epithelium, target cells undergoing cell death (primarily sustentacular cells) were not identical with cells that were involved in regenerative prolifera tion. There are two types of basal cells, the horizontal basal cells and the globosal basal cells . In healthy tissue, the latter represents the majority of basal cells and is mainly involved in normal regeneration of olfactory cells (Ohta and Ichimura, 2001). Even if there is no signifi cant reduction in intracellular pH values that plays a critical role in the process of cell damage, is there any pH-dependent effect on proliferation stimulus on basal cells? Comparing to other toxicants that also induce selective cell death in sustentacular/sensory cells, repa rative cell replication appears to be a unique mechanism that is not necessarily linked to cellular acidification in degenerating cells. The evidence of tumors at non-olfactory sites dem onstrated that proliferative activity was not necessarily associated with cell death and therefore might not be related to the cell acidification.
Bogdanffy (2002) claimed that intracellular acidi fication as demonstrated in the hepatocyte model precedes the morphological signs of cyto toxicity. However, 1000 μM vinyl acetate was not cytotoxic in hepatocytes at the end of 6 days of culturing as evidenced by protein and LDH leakage (Farkas and Tannenbaum, 2005). Furt her proof is needed that intracellular acidification is the initial lesion in cytotoxicity, at least for the olfactory region.
A reduction of intracellular pH as demonstrated in the rat hepatocytes (Bogdanffy, 2002) was – even at a lower level - assignable to cells of the olfactory and respiratory mucosa. For the rat, carboxylesterase activity appears to be in th e same range in the rat liver as in the rat olfactory mucosa as demonstrated in micros omes using methyl methacrylate as a test substrate (Mainwaring et al., 2001) (Table 4.1.2. 8.H). In contrast, carboxylesterase activity is much higher in the human liver than in the human olfactory mucosa.
The changes in intracellular pH were relative small in the test systems mentioned above. However, no prediction could be made on pH homeostasis after prolonged exposure. The experimental studies available examined vinyl acetate or acetaldehyde effects following acute (seconds to minutes) exposure. No data exist on the consequences of prolonged acidification.
The small reduction of intracellular pH may be explained by the low activity and nearly absence of aldehyde dehydrogenases in the olf actory mucosa, which limits the production of acetic acid. Therefore the intracellular acidifica tion may be a process of minor relevance for (cyto-)toxicity and tumor induction at this s ite. Besides the uncertain relationship between small changes in pH and cytotoxicity other pH -related effects on cell transformation could be considered. On irradiated cells with DNA double-strand breaks it was demonstrated that lowering of the extracellular pH from 6.8 to 6. 0 causes inhibition of DNA repair (Jayanth et al., 1994). Whether this is relevant for the carcinogenicity of vinyl acetate is unknown.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 132 • Uncertainties related to the modes of action for the respiratory mucosa:
Beside the nasal tumors originating from the olfactory epithelium, there were also some nasal tumors, which were located in areas of the na sal cavity consisting of non-olfactory epithelial types (Table 4.1.2.8.B). No toxic event was iden tified as a critical step in the development of these tumors, e.g. at the respiratory epithelium of the nose. Whereas rhinitis and metaplasia occurred in the respiratory epithelium of the mouse nose, cytotoxic and/or inflammatory responses to vinyl acetate exposure were not repor ted in rat studies at concentrations which induce tumors (Owen, 1988, Bogdanffy et al., 1994b) . Thus, clear data demonstrating that the toxic lesions in this area were associated to disregulated cellular regeneration resulting in tumor formation are missing. The absence of cyto toxic events at the respiratory epithelium at tumor-inducing concentrations demonstrated th at cytotoxicity did not seem to be the necessary precondition for carcinogenicity of vinyl acetate.

Increased rates of cell turnover were observed in both respiratory and olfactory mucosa after a single 6-hour exposure. When vinyl acetate vapour was inhaled on 20 days (5 d/wk, 6 h/d) (Bogdanffy et al., 1997), increased cell prolif eration was only evident in the olfactory mucosa. These findings were inconsistent with the fact that tumors were observed at both regions.
Also, it was suggested that acidification causes m itogenic response as a critical step in tumor growth of the respiratory mucosa. In-vitro e xposure of cells of a Barrett’s adenocarcinoma cell line to acid media increases cell proliferati on and decreases apoptosis via an activation of the mitogen-activated protein kinase pathwa y (MAPK) (Souza et al., 2002). However, the mode of the development of Barrett’s carci noma of the oesophageal squamous mucosa appears of limited predicted value, since in this in-vitro model cells were exposed to markedly lower pH values (pH 4.0) than those observe d in the nasal mucosa following vinyl acetate exposure. Up to now no substantial evidence of decreased apoptosis has been shown for vinyl acetate-related acidification and no studies investigating mitogenic effects for the inhalation route were available. Instead, some data from oral administration of acetaldehyde and vinyl acetate may be informative: Long-term cell pro liferation experiments demonstrated mitogenic effects of acetaldehyde which induced diffusely enlarged basal cell layer and increased cell proliferation rates (Homann et al., 1997). Compar ed to vinyl acetate metabolism to acetic acid where 3 protons were delivered per molecule vinyl acetate, acetaldehyde oxidation delivers only 1 proton per molecule. This indicates that th e mitogenic response is more likely an effect of acetaldehyde than an effect of acidificati on. The mechanism by which acetaldehyde exerts its mitogenic effect is yet unknown. Whereas only one acetaldehyde concentration (120 mM = 324 mg/kg bw/d) was applied with drinki ng water in the Homann study, the study of Valentine et al. (2002) observed concentration-dependent increases in cell proliferation rates in the oral mucosa of rats receiving 10000 ppm vi nyl acetate or more with the drinking water. No effect was observed at 1000 and 5000 ppm, cytot oxicity was absent in all concentrations tested. In conclusion, acetaldehyde and vinyl acetat e have mitogenic properties, that of vinyl acetate is likely to be mediated through acetaldehyde and has a clear no-effect level.

• Uncertainties related to genotoxic effects:
Since no tumors occurred below the LOAEC for cy totoxic effects in the olfactory region it is unlikely that genotoxic effects were active below the threshold concentration for cytotoxicity.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 133 In contrast no dose-response could be id entified for preceding events in the nonolfactory regions. Dose-related mitogenic eff ects were demonstrated for the oral route where it is assumed that vinyl acetate exerts its acetaldehyde-caused clastogenic effects most efficiently in proliferating cells . This might also be assumed for the sites of contact following inhalation. However, at the moment there are no studies confirming the hypothesis and identifying a LOAE C for this effect in the respiratory tract.

Ig. Actual considerations on the assessment of the mode of acti on for tumors of the respiratory tract (see Table 4.2.1.8.K)
Acetaldehyde is the critical metabolite with a carcinogenic potential.
The distribution and capacity of enzymes res ponsible for vinyl acetate toxicification and detoxification are of major importance to creat e a preliminary understanding of the modes of carcinogenic action. The present understanding is th at acetaldehyde plays a critical role in the tumorigenicity of vinyl acetate.
The principal similarities of toxic and carci nogenic effects of vinyl acetate to those of acetaldeyhde suggest that the hydrolysis pr oduct acetaldehyde is the active carcinogenic metabolite of vinyl acetate.
Acetaldehyde is a biological constituent of many cells and is – beside the release from the man-made sources - ubiquitarily present in ma ny foods and natural sources. Exposure to vinyl acetate induces concentration-related increases in intracellular concentrations of the hydrolytic products acetaldehyde and acetic acid. E fficiency of the absorption is optimal at lowest concentrations and decreases with in creasing concentration (see 4.1.2.1). Increasing concentrations of the vinyl acetate may resu lt in an accumulation of acetaldehyde when the cellular detoxification capacity of aldehyde dehydrogenase is overwhelmed. The toxicity and/or carcinogenicity reflect the function of me tabolic capacity of the target epithelium. The regional and cellular susceptibility to cytotoxic ity corresponds to the distribution and activity of the enzymes involved.
Acetaldehyde is thought to be the responsible metabolite for the genotoxic effects seen in mammalian cell cultures on vinyl acetate.
A hypothesis of a cytotoxicity-related carcinoge nesis is likely to induce tumors in the olfactory region.

• The rat olfactory tissue efficiently catalyses the formation of acetaldehyde and acetic acid.

• Absorption and metabolic transformation of vinyl acetate by carboxylesterase is a concentration dependent process. Due to the absent or low aldehyde dehydrogenase activity (as compared to the carboxylestera se activity) only low concentrations of acetaldehyde can be oxidised. Above a yet non-identified exposure concentration, the production of acetaldehyde exceeds further oxida tion, which results in an intracellular accumulation of acetaldehyde.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 134 • Acetic acid-related cytotoxicity following vinyl acetate hydrolysis appears to be the initial event in tumorigenicity for tumors with origin in the olfactory epithelium.

- A direct genotoxic action of the metabolite acetaldehyde on the restorative epithelium could contribute to tumor initiation.

- Cell death induces increased cell turn ove r of surviving cells or basal cells. DNA synthesis is elevated and the incidence of genotoxic effects is expected to increase.
In conclusion, it appears plausible to explain the sequential steps from cytotoxicity to carcinogenesis for the olfactory epithelium. The sites of epithelial damage correlated with increased cell proliferation as evidenced by basal cell hyperplasia and transformation to squamous metaplasia. The latter was consider ed to be a precursor lesion of benign and malignant tumors that were squamous cell papillomas and carcinomas.

The contribution of intracellular acidification as the initial step leading to cytotoxicity and thereby to carcinogenicity remains uncertain. Shor t term testing indicated that the degree of intracellular acidification was only minor and reve rsible. Also, the site-specific changes in intracellular acidification as predicted in the PBPK-model (Plowchalk et al., 1997) were not consistent with the in-vivo pr eference of cytotoxicity. Genotoxi city data indicate a possible genotoxic effect of vinyl acetate mediated by its metabolite acetaldehyde, which may contribute to the tumor development at concentrations, which were cytotoxic.
At present, a narrative for a threshold concentration for tumor development could be identified for the olfactory region by its cytotoxicity.
A threshold mode of action is thought to be ac tive for tumors with origin in the other nasal regions.
For the other (non-olfactory) tumor sites of the upper respiratory tract (mainly the nasal respiratory epithelium), cytotoxicity was clear ly not a critical event in tumor formation, because tumors occurred at lower exposure concen trations than cytotoxicity. The predictions from the PBPK model, with respect to the degr ee of acidification and th ereby of the cytotoxic response did not reflect the obs erved study data. During the last years, scientific working groups recognised the lack of evidence for the early proposals on acidification as the relevant mode and introduced considerations about the ro le of intracellular acidification in stimulation of cell growth and transforma tion (Lantz et al., 2003). These secondary responses occur only at higher doses.
The following aspects support the hypothesis of a threshold mode of action:

- Absorption and metabolic transformation of vinyl acetate is a concentration dependent process.

- Carboxylesterase activity in the respiratory epith elium is at least half than that of the olfactory epithelium in man and rats. The hydrol ysis rates of vinyl acetate and thereby the intracellular concentrations of acetic acid and acetaldehyde are expected to be markedly lower than in the olfactory epithelium.

- Aldehyde dehydrogenase (ALDH) is the key en zyme for the elimination of acetaldehyde. Its activity is more than 2fold higher in the respiratory epithelium than in the olfactoryR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 135 epithelium. The enzyme activity is sufficient to cope with low concentrations of vinyl acetate and its produced metabolite acetaldehyde. At high concentrations of intracellular acetaldehyde ALDH activity will not be suffici ent to oxidise all acetaldehyde to acetic acid and acetaldehyde may accumulate. Satu ration of metabolism of acetaldehyde by ALDH indicating limited enzyme capacity is suggested to occur at acetaldehyde concentrations of 300 ppm (Stanek and Morris, 1999).

- No toxicity was observed in respiratory epithelium up to 600 ppm in 2-year studies. Regarding acetic acid as the cytotoxic metabolite, acetic acid generation at 600 ppm is below the threshold for cytotoxicity.

- No increase in proliferative activity either measured as proliferation index or as hyperplastic/metaplastic changes up to 600 ppm vinyl acetate in (LOAEC 1000 ppm). It is assumed that increased cell proliferativ e activity is acetaldehyde-related. As no cytotoxicity or other relevant effect wa s seen up to 600 ppm, no significant intracellular concentration of acetaldehyde is expected to occur.

- In accordance to data from oral studies on mitogenic action of vinyl acetate a mitogenic action could be assumed above a threshold con centration. Due to the lack of adequate studies on the respiratory tract, evidence fr om studies on gastrointestinal tract was considered: Basal cell hyperplasia and epithelia l hyperplasia in the gastrointestinal tract without preceding cytotoxicity were evident at ≥ 10000 ppm (NOAEL 5000 ppm ≈ 1200 mg/kg/d, 92-day mouse study, Valentine et al., 2002).

- Tumor response was seen at ≥ 600 ppm vinyl acetate, no tumors were observed at concentrations below.

- It is assumed that acetaldehyde-caused genotoxicity is active at vinyl acetate concentrations that cause acetaldehyde accumulation.

- The toxicological relevance of minimal reduction in pH remains questionable.

- Actually, an exact threshold concentrati on for acetaldehyde accumulation could not be estimated for the non-olfactory region.

- Since no biological response in the respir atory mucosa was observed in long-term inhalation studies up to 200 ppm vinyl acetate e xposure, it is concluded that the cellular integrity is not disrupted.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 136 Table 4.1.2.8.K: Critical steps in vinyl acetat e tumor formation in the respiratory tract:

VA Absorption

Ø

Metabolism of vinyl acetate to acetaldehyde and acetic acid in:

Olfactory epithelium

Sustentacular cells + ne uronal (sensory) cells:

Carboxylesterase activity +++

ALDH activity -

Ø Olfactory epithelium

Basal cells + Bowman’s glands:

Carboxylesterase activity +++
ALDH activity (+)

Ø Respiratory epithelium

Respiratory epithelium cells:

Carboxylesterase activity +

ALDH activity +++

Ø

High acetaldehyde production

No detoxification of acetaldehyde

Intracellular accumulation of acetaldehyde

Cytotoxicity at 200 ppm

Ø High acetaldehyde production

Very limited detoxification of acetaldehyde

Intracellular accumulation of acetaldehyde

Ø Limited acetaldehyde production

• Up to a threshold concentration: Efficient detoxifi cation though high ALDH capacity
No toxic effect up to 200 ppm

C. Above threshold concentration: Imbalance of acetaldehyde production an d detoxification

Intracellular accumulation of acetaldehyde
Ø

Secondarily to cytotoxicity of the primary target cells:

Restorative cell proliferati on of surviving basal cells

Replacement by respiratory-like epithelium

and squamous cell metaplasia

Ø Cell proliferation due to direct mitogenic effe c

Ø

Genotoxic effects of acetaldehyde on proliferating cells (inclu sive tumor relevant genes)

Tumor initiation and development

Tumor response: LOAEC 600 ppm

Cytotoxicity: LOAEC 200 ppm/NOAEC 50 ppm Genotoxic effect of acetaldehyde on proliferating cells (inclusive tumor relevant genes)

Tumor initiation and development

Tumor response: LOAEC 600 ppm/NOAEC 200 ppmR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 137 II. Gastrointestinal tract tumors

IIa. Postulated mode of action
From the recently reported carcinogenicity studi es in rats and mice (Umeda et al., 2004a, Maltoni et al., 1997, Minardi et al., 2002) which at the first time gave indication that vinyl acetate is also carcinogenic after oral administ ration, it is assumed that carcinogenicity of vinyl acetate is a direct effect on the surface epithelium of the oral cavity, larynx, esophagus, and forestomach exposed. Temporarily, it was a ssumed that vinyl acetate metabolism in these tissues leads to cytotoxicity accompanied by reparative hyperplasia. The continuous reparative stimulus in the presence of high concentrations of acetic acid and acetaldehyde then leads to mutation, cellular transformation, and tumor development.
Meanwhile increased cell proliferation due to mitogenic response to the long-term uptake of vinyl acetate was discussed to lead to tumo r formation instead of apparently absent cytotoxicity-related mode of action (Valentine et al., 2002). Similar to the nasal regions, it was thought that in the presence of excess, non-physiological levels of acetaldehyde and low pH inducing mutations in genetic material will result in tumor formation.
IIb. Key events associated with the hypothesis
Hydrolytic esterase activities, mainly carboxyl esterases, were also found in the mucosal epithelium of the oral cavity (Y amahara and Lee, 1993). Different mucosal regions of the oral cavity possess vinyl acetate hydrolysis activity in the concentration range of 0.05-10 mM vinyl acetate. The enzyme activity V max was 90 and 6 nmol/min in rat and mouse oral mucosal tissue, respectively. The K m

for vinyl acetate hydrolysis were 0.5 and 0.9 mM, respectively, and were at about 100fold below the concentrati ons of vinyl acetate that were administered orally suggesting that saturating conditions would exist

. The total activity was similar in pooled homogenates from F344 rats and BDF mice. About 2% of total activity were found in the oral rinse fluid; the saliva and/or oral bact eria are possible sources of esterase activity. In both species the dorsal interior region contained more activity than other regions (Morris et al., 2002). No indication on cytot oxicity was observed in the oral rinse fluid assessed for leakage of acid phosphatases and Evans blue dye after intravenous administration. The concentration of acid phosphatase was not si gnificantly altered. Evans blue dye was significantly increased at 10 mM (intended to correspond to the dosage of 24000 ppm in the 90-day study, DuPont, 2000). Howe ver, Evans blue extravasation is not specific, since sensory nerve activation and/or increased sa livation could also interfere with plasma extravasation.
The distribution and immune-reactivity of carboxyl esterases in the oral mucosa have been characterised by Robinson et al. (2002). In gene ral, the staining was most intensive in the stratum corneum, less prominent in the stratum spinosum and (nearly) absent in the basal cell layer. The staining was markedly variable among different sites within the oral cavity (range from slight to intensive). High staining inte nsity was found in the buccal mucosa and the upper palate, which is in line with the high ac tivity reported for the dorsal interior (hard palate) region by Morrris et al. (2002). Overall the carboxylesterase activity is significantly lower in the oral mucosa than in the olfactory epithelium (about 100fold).
Furthermore, aldehyde dehydrogenase activity is present in the upper gastrointestinal tract. Enzyme activities were detected in human mucosa of the gingiva, tongue, oral cavity and stomach (Dong et al., 1996, Hedberg et al., 2000, Yin et al., 1997). The aldehydeR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 138 dehydrogenase activities at 20 mM acetaldehyde were determined to be 169 ± 19 and 50.3 ± 8.1 nmol/min/g tissue for the gingiva and tongue, respectively (Dong et al., 1996) It is also assumed that rats and mice possess aldehyde de hydrogenase activity in the oral cavity. For rats, enzyme activity was demonstrated for the st omach, liver, small intestine, large intestine, and rectum (Koivisto and Salaspuro (2003), Pr onko et al., 2002, Green et al., 2002), but so far mouse data on aldehyde dehydrogenase were only available for the forestomach and stomach (Green et al., 2002). Determination of enzyme activity using 5 mM acetaldehyde revealed lower activity than in the respiratory tract, at least for the rat (Pronko et al., 2002).
Data on in situ distribution among the differe nt regions and cell layers and data on the intracellular localisation of aldehyde dehydrogena se in the upper digestive tract are yet not available. No information about the enzymatic activity is available for the oral cavity and esophagus.
The potential of vinyl acetate for reducing the intracellular pH was confirmed in a slice preparation of buccal mucosal cells from the mouse (Nakamoto et al., 2005). The pH dropped 0.35 pH units during a 2.5 min exposure time to a concentration of 1 mM vinyl acetate. While no response was seen at 0.1 mM vinyl acetate, dose-dependent reduction in intracellular pH occurred at concentrations from 0.3-1 mM ( Δ pH ca. 0.1 at 0.3 mM). Interestingly, the extent of acidification was greater fo r isolated single cells of buccal mucosa than for intact epithelium.
In line with the foregoing examinations, none of the oral cancer studies reported that cytotoxicity of the surface epithelia of the ga strointestinal tract nor any other organ lesion occurred in rats and mice treated with vinyl acetate via drinking water. Measurement of cell proliferation in 92-day drinking water studi es demonstrated significantly increased proliferation rates of oral mucosa cells in ra ts and mice without any histopathological lesions of the surface epithelia (DuPont, 2000, Valentine et al., 2002).
IIc. Dose-response relationship
There are no data on dose response of effects after oral administration suggestive to be a critical cytotoxic step in the tumor development.
Lesions which accompanied the vinyl acetate-i nduced tumors in mice receiving vinyl acetate by the drinking water for 2 years were basal cell activation, epithelial dysplasia and squamous cell hyperplasia of the gastrointestinal tract ep ithelia (Umeda et al., 2004a). Because of their nature it can be supposed that they represen t preneoplastic alterations in the sequential development to squamous cell papillomas and car cinomas. At some target localisations, these lesions were also evident at concentrati on below tumor-inducing concentrations of 10000 ppm (see Table 4.1.2.8.C). The lowest dose at which squamous cell hyperplasia of the stomach occurred was 400 ppm in the mouse st udy of Umeda et al. (2004a). The earliest changes in the oral cavity were basal cell activation and squamous cell hyperplasia at 2000 ppm. Mice, which received vinyl acetate via dri nking, water for 78 weeks (Maltoni et al., 1997) showed tumors and dysplastic lesions of the gastrointestinal tract at 5000 ppm (Table 4.1.2.8.D). Relatively low, but in comparison to th e controls elevated incidences of tumors or dysplasias were found in some test groups at 1000 ppm but data were inconsistent between groups of breeders and offspring. For these groups, it can be argued that the treatment duration of 78 weeks was too short and that the treatment-free period until the end of the study allowed at least in part recovery from dysplasia and hyperplasia. A clear increase inR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 139 dysplastic changes was seen at the end of lif e of rats treated for 104 weeks with drinking water containing ≥ 1000 ppm vinyl acetate (Minardi et al., 2002).

There seems to be some evidence that a dos e-relationship of hyperplastic and dysplastic lesions with the tumor growth which started at 2000 ppm in the oral mouse cancer bioassay. In the rat, preneoplastic lesions were seen at the same dose which induced a marked increase of tumors in the oral cavity (10000 ppm, Umeda et al., 2004a; Table 4.1.2.8.A), but no preneoplasias were found at lower dosages. Si ngle squamous cell carcinomas of the oral cavity occurred in female rats at the lower doses of 400 ppm and 2000 ppm without being accompanied by any other change. Although the in cidences of this single tumor are not significantly different from control group, the tumors were of the same nature as those seen at 10000 ppm and could therefore not excluded to be treatment-related. With a conservative view, the no-effect level for tumor response was 2000 ppm in mice and no such effect-level was derived for the rat, where the lowest concen tration tested was the lowest-observed effect level of 400 ppm.
Cell proliferative hyperactivity was a clearly dose-related effect occurring only at high concentrations. 2- to 3-fold increases in ce ll proliferation rates we re found in mice after 92 days of exposure to 10000 or 24000 ppm vinyl acetat e compared to control mice (Valentine et al., 2002). In rats, cell proliferation was also significantly increased at 24000 ppm. Increase at this concentration was lower than in mice (less than 2-fold higher than in control rats) which may be attributed to lower doses per g bodyweight in rats (1400 mg/kg bw/d) than in mice (2300 or 5300 mg/kg bw/d).
Increases in proliferation rates were higher in mandibular than in maxillar regions and were interpreted to parallel the tumor outcome (Umeda et al., 2004a). Also, the distribution pattern might be reflective for the normal proliferative activity which was shown to be highest in the floor of mouth and ventral tongue of sample s from healthy humans (Thomson et al., 1999). The incidence of oral cavity neoplastic lesions wa s reported to be higher in the lower jaw than the upper jaw either in rats and mice and the in cidence of these oral cavity lesions was about 3-fold in mice compared to rats. Although hydrolytic activity was 2-15-fold higher in homogenated mucosa from the dorsal interior re gion than in other regions (Morris et al., 2002), the prevalence of tumors in the lower ja w can be explained by gravity-related exposure of the lower jaw regions during feed consump tion. In addition, the metabolic activity of homogenated tissues may not correctly reflect the in situ activity.
The effective tumor doses of vinyl acetate doses appeared high for the oral route compared to the tumor effective concentration of the inhalati on route. This may be discussed as related to relatively low vinyl acetate hydrolytic activity in the oral cavity, which was 100-fold less than those in nasal tissue homogenates.
The highest concentrations/dosages chosen in the studies available were considered not to exceed the maximal tolerated dose (MTD) (cf. Appendix Vinyl Acetate_MTD_0209). Unspecific signs of toxicity such as reduction of body weight gain were attributable to lower water consumption (where measured) and/or f eed consumption (secondarily to the low water uptake?), as no indications on target organ toxic ity or other signs of systemic toxicity were identified.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 140 IId. Temporal relationship
As no underlying toxic event was evident in or al studies, and none of the cancer studies contained interim sacrifice groups, no data are available to give information on the temporality of sequential steps for tumor deve lopment based on cytotoxicity as the initial step. The appearance of mitogenic effects after 92-days of drinking water is assumed to be a precursor event in tumor development (DuP ont, 2000). The relatively small increase of proliferative index was interpreted as well corresponding to the long latency period of tumor development.
IIe. Strength, consistency, specificity of association
In contrast to the mode of action postulated, the evidence of basal cell activation observed at several sites of the gastrointestinal tract a nd increase in cell proliferation in oral cavity mucosa gave arguments for that the devel opment of tumors was preceded by increased proliferative activity of basal epithelial cells without any cell death preceding. The normal differentiation and maturing of cells was re placed by dysplastic and metaplastic changes representing intermediate stages of tumor development. This observation and the absence of preceding cytotoxicity does not support the postulated a cytotoxicity-related mode of action.
IIf. Biological plausibility and coherence
Hyperproliferation may be associated to infla mmation and cell death of superficial epithelial cells in spontaneous human diseases or in rodents exposed to xenobiotica. This general assumption is insufficient to proof that vinyl acetate carcinogenesis needs such toxic precursor stages.
At 10000 ppm vinyl acetate, higher tumor incidences in the oral cavity in mice than in rats parallels the higher cell proliferative activity in mice (Valentine et al., 2002).
IIg. Inconsistency, uncertainties and data gaps
Overall, the database for the oral route is less than for the inhalation route.
The oral carcinogenicity studies di d not give any hint for cytotoxicity as a first step of tumor development. Additionally, none of the short and me dium term oral studies in rats neither the 90-day drinking water studies in rats and mice demonstrated irritative/toxic effects on the gastrointestinal tract epithelium.
The test substance administered in positive or al cancer studies contained impurities, which were suspected to contribute to carcinogenesis. The test substance of Japanese oral cancer study contains 5 ppm hydroquinone, a metabolite of benzene, which was shown to increase tumor rates in the kidney of male F344 rats, the incidences of mononuclear cell leukemia in female F344 rats, and of hepatocellular tumors in female B6C3F1 mice (Kari et al., 1992). The test substance of the Maltoni study (Malt oni et al., 1997) contained benzene (30-45 ppm) methyl and ethyl acetate (50 ppm) crotonald ehyde (6-16 ppm), acetaldehyde (2-11 ppm). acetone (330-500 ppm). At least the tumors of the Zymbal glands observed in the Maltoni study may be discussed to be associated to th e benzene impurity (Maltoni et al., 1989, NTP, 1986, Huff et al., 1989). However, the concentra tions of impurities were extremely low to support this assumption.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 141 The higher tumor incidences in mice than in rats, both exposed to a concentration of 10000 ppm, were neglected if the intake of vinyl acetate per kg bodyweight was calculated (Valentine et al., 2002). Although tumor rates shoul d be expected to mirror the vinyl acetate concentration, an explanation for the species di fferences could not yet be given (e.g., due to lack of data on aldehyde dehydrogenase activity).
Nakamoto et al. (2005) stressed the importance of intracellular acidification for the induction of the mitogenic response conferring the vinyl acetate-related cell proliferation to those observed in the gastrointestinal reflux dis ease (Barrett’s oesophagus). Whether the excess drop of pH seen in Barrett’s disease could be transferred to vinyl acetate exposure remains speculative due to the little reduction in intracellular pH.

IIh. Actual considerations on the assessmen t of mode of action for tumors of the gastrointestinal tract
Based on the actual information, the assumption of cytotoxicity-mediated carcinogenicity of vinyl acetate was considered not to be plausible for the gastrointestinal tract. Up to now, the link between observed cytotoxicity and tumors in the gastrointestinal tract of animal studies supporting the postulated mode of action is mi ssing. Therefore, the contribution of other mode of actions has to be considered. Although the overall database is much less than for the inhalation route there are similarities among the tumor sites.

Acetaldehyde is the critical metabolite with a carcinogenic potential.
Although carboxylesterase activity is low in the ep ithelium lining of the gastrointestinal tract, acetaldehyde is thought to be significant for tumo r development. The high test concentrations needed to induce tumor response are thought to be reflective of the low hydrolytic activity.

A thresholded mode of action is assumed to be active in the tumor development in the gastrointestinal tract.

- Vinyl acetate is hydrolysed by the mucosal carboxylesterase to acetic acid and acetaldehyde.

- Due to the fact that cytotoxicity could be ruled out as a precedent lesion and considering that the metabolism is in principle comparable to the nasal regions the pathways of tumor development in the upper gastrointestinal tractis expected to be comparable to the nonolfactory (respiratory) regions.

- Acetaldehyde is oxidised by aldehyde dehydroge nase. The enzyme activity will be high enough for the oxidation of the physiological concentrations of acetaldehyde. As significant increases in tumor response were s een at rather high concentrations of vinyl acetate (10000 ppm for rat and mouse (Umeda et al., 2004a), ≥ 5000 ppm for mice (Maltoni et al., 1997, 1000 ppm for the rat (M inardi et al., 2002)) enzyme activity might cope for the low concentrations of produced acetaldehyde without any harmful effect on cell viability and integrity. However, it is unlikely that there is enough activity forR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 142 effective acetaldehyde oxidation at higher concentrations of vinyl acetate; and acetaldehyde may accumulate.

- Accumulated acetaldehyde produces genotoxic effects.

- High concentrations of vinyl acetate are mitogenic. A dose-related increase of cell proliferative activity increased dos e-related above 10000 ppm in mice ( ≥ 2300 mg/kg bw/d), no effect was seen at 5000 ppm. In rats, a less than 2-fold increase in proliferative activity was observed at 24000 ppm in rats (1400 mg/kg bw/d).

- Cytotoxicity was not obvious up to tumor-induci ng concentrations and therefore could be ruled out as a precedent change in the tumor development. The cleavage product acetic acid is also discussed to induce intracellular acidification. A reduction of intracellular pH was also seen for buccal mucosa. As for the nasal mucosa the extent of pH-reduction is low, which raises the question on the significan ce of this low range shift in intracellular pH.

- The exact concentration of vinyl acetat e where production of acetaldehyde and its removal starts to be imbalanced could not be estimated by data available. It is therefore proposed to select the most sensitive biol ogical effect with putative toxicological relevance as a starting point to estimate a threshold. Since no clear NOAEL could be determined from the carcinogenicity studies , the vinyl acetate concentration (400 ppm) inducing the single tumors in the rat oral cavity were chosen as the LOAEL.

Conclusion:
In animals, long-term inhalation and oral ad ministration of vinyl acetate produce tumors at the primary site of exposure, the surface epithe lium of the respiratory tract and of the upper gastrointestinal tract. There was no indication on systemic toxicity on any other organ or tissue outside the administration routes. Tumo rs observed in other organs following oral uptake could not clearly be attributed to vinyl acetate administration.
Experience from human exposure did not give indication that vinyl acetate exposure was associated to increased tumor rates.
Based on animal data a clear tumor response to vinyl acetate exposur e was seen at 600 ppm (rat, Bogdanffy et al., 1994b) for the inhalation r oute; for the oral route a marked increase of tumor rates has been observed at 1000 ppm (rat (offspring); 70 mg/kg bw/d, Minardi et al., 2002), at 5000 ppm (mouse; 750 mg/kg/day, Malt oni et al., 1997) and at 10000 ppm (male rat 442 mg/kg bw/d, female rat 575 mg/kg bw/d, Umed a et al., 2004a). Due to limitations in the study design in the studies of Maltoni et al . and Minardi et al., the study of Umeda is considered of higher predictivity. For lower doses , there is concern that occasional findings of tumors of the same types that have been obs erved at high doses and which might also be related to vinyl acetate exposure. Thus, the lowe st concentration suspected to be carcinogenic was 200 ppm for the inhalation route (LOAEC) and 400 ppm for the oral route (LOAEL, male rat 21 mg/kg bw/d, female rat 31 mg/kg bw/d, Umeda et al., 2004a). Clearly tumor free dosages were not established in carcinogenicity studies for the oral route, since 400 ppm were the lowest concentrations tested. Subchronic i nhalation studies did not reveal any indication on proliferative response at concentrations of 50 ppm, and this concentration was verified inR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 143 carcinogenicity studies. Therefore the concentr ation of 50 ppm is considered as NOAEC for risk characterisation on carcinogenicity via i nhalation. For the oral route, no NOAEL was estimated, 400 ppm (21 mg/kg bw/d male rat, 31 mg/kg bw/d female rat) is proposed as LOAEL for the risk characterisation.

Table 4.1.2.8.L: Effective concentrations for t oxic and proliferative responses to vinyl acetate at tumor sites
Target tissues Upper respiratory tract Upper digestive tract
Effect Olfactory regi on Other non-olfactory regions
Cytotoxicity
Epithelial degeneration/necrosis /atrophy Rat ≥ 200 ppm*

Mouse ≥ 200 ppm* Rat 1000 ppm ** No indication of cytotoxicity up to

24000 ppm***

No-adverse-effect concentration for toxic effects Rat ≥ 50 ppm*

Mouse ≥ 50 ppm* Rat 600 ppm*
Mouse 600 ppm* Rat 24000 ppm #

Mouse 24000 ppm #

Preneoplasias and Neoplasias
Hyperplasias Metaplasias Rat ≥ 200 ppm*

Mouse ≥ 200 ppm* Rat ≥ 1000 ppm**

Mouse ≥ 600 ppm* Mouse ≥ 2000 ppm ##

Weak or questionable tumor response Rat ≥ 200 ppm* Rat ≥ 400 ppm ##

Mouse 2000 ppm ##

Clear tumor response Rat ≥ 600 ppm * Rat ≥ 600 ppm * Rat 10000 ppm ##

Mouse ≥ 5000 ppm ###

Concentration without tumor response Rat 50 ppm*
Mouse 600 ppm* Rat 200 ppm*
Mouse 600 ppm* Rat LOAEC 400 ppm #
Mouse 2000 ppm ###

*Bogdanffy et al., 1994b **Bogdanffy et al., 1997 # DuPont, 2000 ## Umeda et al., 2004a ### Maltoni et al., 1997

In conclusion, vinyl acetate exposure produced tu mors at the site of first contact along the exposure routes. A thresholded mode of carci nogenic action is thought to be active. The observed tumor responses are reflecting the target site-specific enzyme activities:
Following inhalation and oral exposure vinyl acetate is rapidly hydrolysed by carboxylesterases leading to the formation of acetic acid and acetaldehyde which is further converted into acetic acid in the presence of aldehyde dehydrogenases. Intracellular aldehydeR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 144 dehydrogenase activity is limited, at higher c oncentrations of vinyl acetate it will not be sufficient for the oxidation of generate d acetaldehyde. Thus, at high vinyl acetate concentrations non-physiologically high con centrations of acetaldehyde are produced. Acetaldehyde is a physiological intermediate w ith low background concentrations. Its adverse effects (genotoxicity and mutagenicity ) are limited to non-physiologically high concentrations. Therefore, a threshold mode of action is assumed for vinyl acetate.
Above threshold concentrations, cytotoxicity (only at the olfactory mucosa), mitogenic actions and genotoxic actions occurred.
Cytotoxicity mainly contributed by acetic acid is the earliest lesion in the olfactory mucosa. Next stages in the continuum to tumor deve lopment include the responsive restorative cell proliferation and simultaneously occu rring genotoxic effects of acetaldehyde.
Increased cell proliferative activity was observed at high concentrations of acetaldehyde or vinyl acetate. Its occurrence was not linked to cell toxicity as a precondition.
Data on vinyl acetate are in line with the idea that vinyl acetate genotoxicity is mediated by acetaldehyde. Increasing concentrations of acetal dehyde produce genotoxic actions at the site of contact. It has to be taken into consid eration that acetaldehyde occurs naturally in mammalians cells and is part of the physiological cellular metabolism.
The systemic bioavailability of vinyl acetate or its metabolite is low (cf. 4.1.2.1). In vivo genotoxicity tests showed that systemic genotoxic ity appears to be limited to toxic doses. This is in line with the absence of systemic carcinogenic effects.
The threshold concentration leading to acetal dehyde accumulation could not yet be estimated. Using in vitro test systems as a surrogate for a site of contact model, in vitro data for several genotoxic endpoints are suggesting for a thres hold concentration above which acetaldehyde exerts its genotoxic action. A NOAEC of 0.1 mmol/l for chromosomal aberrations and 0.03 mmol/l for SCE was determined. Since for the in vivo situation no biomarker for the limitation of acetaldehyde oxidation is available, it is proposed to use the identified NOAEC, respectively the LOAEL from the most sensitive bi ological effects as a surrogate to derive a threshold concentration for risk characterisation purposes.
Overall, it is considered that the critical ev ents in vinyl acetate carcinogenesis do fit to the criteria for the exceptional cases where genotoxic action is thought to be thresholded 7

.

7 Technical Guidance Document on Risk Assessment, Hu man Health Risk Characteris ation, revised chapter, 4.13.3 There are two general cases where mutagenicity may be shown to have a threshold: (1)... does not apply here.(2) where the toxico-kinetic considerations clear ly demonstrate that mutagenic metabolites will only be produced in vivo at very high exposures to the parent s ubstance which are unlikely to be achieved in realistic human exposure scenarios. For exampl e, where the active metabolite is onl y produced by a metabolic pathway that occurs when other preferential pa thways are saturated, or where there is very rapid removal of the active metabolite by conjugation or detoxification, such that no biological significant am ounts reach the DNA in vivo, except when these pathwa ys are overwhelmed.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 145 From animal data it is concluded that vi nyl acetate might pose a cancer risk for humans exposed to the substance via the inhalation or or al route. Carcinogenicity is thought to act via a secondary mechanism and the concern may be relevant above threshold concentrations.
The observed effects are thought to be releva nt for the human. For the respiratory tract humans may be less sensitive than the rat due to a lower carboxylesterase activity in the nasal

mucosa.

Classification
According to the EU criteria for classification vi nyl acetate is proposed to be classified as a Carcinogen, Category 3 and labelled as Harmful, Xn, R 40.

Justification:

- There is no adequate database on humans.

- Relevant cancer studies for the classifica tion proposal were Owen (1988), Bogdanffy et al. (1994b), Umeda et al., (2004a), Minardi et al. (2002) and Maltoni et al. (1997). Test concentrations in these studies did no exceed the MTD (cf. Appendix Vinyl Acetate_MTD_0209).

- Vinyl acetate was carcinogenic in two animal species each at both sexes.

- Carcinogenic potential was demonstrated for two administration routes: inhalation and oral.

- Vinyl acetate was carcinogenic at the site of first contact, the surface epithelium along the exposure routes.

- Spontaneous rates of nasal tumors and epithe lial tumors from the upper and lower airways and from the upper gastrointestinal tract in the test species used are known to be very low.

- All target organs of tumor development were considered to be relevant for humans.

- No species-specific mode of action for vinyl acetate carcinogenesis was identified.

- The carcinogenic effect of vinyl acetate is thought to be related to genotoxic activity of the metabolite acetaldehyde. Comparable tumo r findings and genotoxicity data from acetaldehyde support this assumption.

- A threshold mechanism is thought to be active. Tumor development is reflecting the target site-specific enzyme activities involved in the hydrolysis of vinyl acetate and the metabolism of acetaldehyde. At higher concentrations the enzyme activities will not be high enough for the oxidation of generated acetadehyde. Then acetaldehyde accumulates intracellularly and is causing increased cell proliferative activity, increased DNA adduct formation and DNA damage (clastogenicity). Cell proliferative activity of acetaldehyde and DNA adduct formation are only active above certain (threshold) concentrations.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 146 - As for acetaldehyde, mitogenic action was seen at high local concentrations of vinyl acetate. 10000 ppm or higher concentrations of vinyl acetate produced proliferative hyperactivity in mice whereas no such effect was observed at concentrations up to 5000 ppm. The exact mechanisms how the mitogenic response is initiated are unknown.

- Cytotoxicity was assumed as one contributi ng mode of carcinogenesis in the olfactory mucosa diminishing the resistance of the olf actory mucosa due to its site-specific high carboxylesterase activity and the low alde hyde dehydrogenase activity. The assumption was thought to be supported by consistent dos e-response and time-response relationships between cytotoxic effect and tumor growth.

- In the olfactory epithelium a multistage hypothe sis of carcinogenesis is likely to be based to initial cytotoxicity, responsive cell prolifer ation and associated with genotoxic action of its metabolite acetaldehyde.

- For the other tumor sites, the non-olfactor y (respiratory) epithelium as well for the mucosa of the upper gastrointestinal tract , concentration-dependent increased cell proliferation coupled with the genotoxic acti on of acetaldehyde at high concentrations of acetaldehyde were assumed to result in tumor development.

- For the inhalation route, cytotoxicity in the olfactory mucosa is thought to be the most sensitive effect related to the tumor response and is therefore taken for quantitative risk assessment. Cytotoxicity and related reparativ e cell proliferation are assumed to be early events in the tumor development in this region. A NOAEC (50 ppm) established for the cytotoxic effects in the olfactory mucosa is proposed to be used as a threshold concentration. For the oral route, the lowest tumor dose (400 ppm corresponding to 21 mg/kg bw/d) is proposed as basis to calculate a threshold concentration.
In September 2007 the TC C&L agreed on Carc. Cat. 3; R40.

4.1.2.9 Toxicity for reproduction

Animal data:
Fertility impairment
Groups of male and female Crl:CD(SD) rats were administered vi nyl acetate in drinking water at nominal concentrations of 0 (cont rol), 200, 1000 or 5000 ppm v/v (equivalent to about 20, 100, or 500 mg/kg bw/d, calculated on an assumed water consumption of 10% of body weight) over two generations. The test solu tions were freshly prepared daily and overformulated by 5% to correct for vinyl acetate losses over 24 hours. F 0 rats (18 males and 36 females per dose group) received vinyl acetate fo r 70 days prior to mating and the treatment continued throughout gestation and lactation. Fr om the first litters groups of 25 male and 25 female pups (F 1 ) were selected. They continued to receive vinyl acetate for 70 days after weaning and were then allowed to mate with in their groups to produce the second generation (F2). The study was terminated following weaning of the F2 litters.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 147 The reproductive performance of the F0 and F1 animals was evaluated from indices which included litter number, viability and size. Weights of the F1 and F2 pups were recorded from birth to weaning (on lactation days 1, 7, 21) as were developmental and functional parameters (on lactation day 21). Post-mortem examinations were carried out on the F0 and F1 parental animals and on 10 male respectively female pups from each group of the F1 and F2 litters. Neither clinical abnormalities nor treatment-rela ted mortality was observed in any of the groups. Water consumption was significantly reduced in the 5000 ppm groups in the F0 and F1 generations and in the 1000 ppm females. Th is was associated with significantly reduced body weight gain during lactation in the F0 fe males at 5000 ppm and in the F1 females at 5000 and 1000 ppm. Pup weights in the F1 genera tion, but not in the F2 generation were statistically significantly lower at 5000 ppm th an those of controls when evaluated on lactation day 21. No effects were observed in the reproductive performance of the F0 animals, but the mating of the F1 animals resulted in a lower number of pregnancies in the 5000 ppm group (19/24) compared with controls (24/25) leading to a reduced number of litters. The difference was slight and not statistically signi ficant, however the effect was attributed to lower fertility. Therefore an additional cross-mating trial of control and 5000 ppm male and female rats of the F1 generation was performe d. Fewer pregnancies occurred when the control females were mated with the 5000 ppm males resulting in a mating index of 76% and a fertility index of 100% indicating that the lower numbers in pregnancies were rather attributable to poor mating than to impaired fertility. No decrease was apparent when the 5000 ppm females were mated with the control males. All other observations, including those made at necropsy and subsequent histopathologi cal examinations showed no adverse effects due to vinyl acetate. There were no compound-related testicular changes evident in this study.
In summary, no effects were seen on reproductiv e performance, or on the resulting litters of male and female rats exposed to 200 or 1000 ppm vinyl acetate in dr inking water. At 5000 ppm a lower number of females became pregna nt, although cross-mating studies suggested that the effect, which was marginal and not sta tistically significant, was associated with male reproductive performance. Effects on litters of animals exposed to vinyl acetate were confined to the 5000 ppm group of the F 1 pups only, were a significant reduction in weight gain was observed on lactation day 21. No such effect was observed for the F 2 pups. The lower weight gain at weaning of the F 1 pups was associated with significantly reduced water consumption and body weight gain of their mothers during the lactation period. Under the conditions of the study, the NOAEL was considered to be 1000 ppm (Mebus et al., 1995).
In hybrid (C57Bl/6JxC3H/He) F 1 male mice, intraperitoneal injections of 125, 250, 500, 750, or 1000 mg/kg bw (vinyl acetate dissolved in o live oil) on 5 consecutive days resulted in 80 respectively 100% mortality at the 750 and 1000 mg/kg dose level and in a dose-related loss of body weight and a dose-dependently reduced regain in body weight during the injection period at the lower dose levels. From these gene rally toxic dose levels reduced mean relative testicular weight was observed at the 125 a nd 500 mg/kg dose levels, however not at the 250 mg/kg dose level, as well as sperm abnor malities at the dose level of 500 mg/kg bw. Epididymal sperm counts at 5 weeks after treatment amounted to 5.60 + 0.51, 5.58 + 1.38, 6.17 + 1.03, and 4.10 + 1.80 millions/ml for the control, 125, 250, and 500 mg/kg dose groups (Lähdetie, 1988).

Developmental toxicityR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 148 Groups of 23 mated female Crl:CD(SD)BR rats were given vinyl acetate in drinking water (Hurtt et al., 1995, Irvine, 1980) from day 6 to da y 15 of gestation at nominal concentrations of 0 (control), 200, 1000, or 5000 ppm (about 0, 25, 100, or 500 mg/kg bw/d). The test solutions were freshly prepared daily and ove r-formulated by between 7 and 10% to correct for vinyl acetate losses over 24 hours. On day 20 of gestation terminal examination of the dams and their uterine contents was conducted.
There were no statistically significant differe nces between treated and control groups of animals in appearance, behaviour or pregnancy index. Initially, there was a slightly reduced intake in food and water associated with sli ght retardation of body we ight gain in the 5000 ppm group; the statistically significant lowered water intake was assumed to reflect the bad palatability of the vinyl acetate water solution. No changes attributed to treatment were observed in the post mortem examinations of the dams or in the examination of fetal parameters including the total incidence of abnormalities. It was concluded that the administration of vinyl acetate in drinking wa ter at doses up to 5000 ppm v/v, a dose which resulted in slight maternal toxicity, was not embryotoxic or teratogenic in the rat.
Groups of 24 mated female Crl:C D(SD)BR rats were exposed to vinyl acetate vapours (Hurtt et al., 1995) from day 6 to day 15 of gestation at concentrations of 0 (control), 50, 200, or 1000 ppm (equivalent to about 100, 205, and 1025 mg/kg bw/day, based on a respiratory rate of 0.8 l/min/kg for rats) for 6 h/d. At 1000 ppm, severe maternal toxicity (marked reduction in body weight gain, congestion of the lungs) and so me signs of fetotoxicity occurred. Fetal toxicity was evident by a statistically signifi cant decrease in mean fetal weight and mean crown-rump length in the fetuses of the 1000 ppm group. In addition, there was a statistically significant increase in the incidence of minor skel etal alterations (mainly delayed ossification) in fetuses from dams exposed to 1000 ppm. In summary, vinyl acetate did adversely affect both the dam and the conceptus at an inhale d concentration of 1000 ppm, but not at lower exposure levels. The NOAEC for the inhalation study was considered to be 200 ppm.

Human data:

No data available.

Summary for toxicity of reproduction
Vinyl acetate has been investigated in rats for adverse effects on reproductive performance and fertility via the oral (drinking water) route of exposure and in mice for adverse effects on male reproductive organs via the i.p. exposure route. Vinyl acetate was shown to reduce testicular weight and to induce sperm abnorma lities in mice, however at toxic dose levels inducing mortality and body weight loss. Vinyl acetate was further shown to have marginal influences on reproduction at oral exposure leve ls that lead to significantly reduced water intake (probably due to palatability) associat ed with significantly reduced body weight gain. The observed effects comprised reduced pup weights and slightly lower numbers of pregnancies. Distinct reproduction related advers e effects of vinyl acetate were not evidenced from a two generation study with rats for drinki ng water concentrations of up to and including 1000 ppm.
The developmental toxicity of vinyl acetate has been investigated in rats via oral (drinking water) and inhalation exposure routes duri ng organogenesis. No embryo/fetotoxic orR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 149 teratogenic effects were observed for the oral route of administration at drinking water concentrations of up to and including 5000 ppm. Fe totoxic effects, revealed during inhalation exposure, were confined to high dose levels only, where severe maternal toxicity was observed. However, vinyl acetate did not advers ely affect both the dam and the conceptus at an inhaled concentration of up to and including 200 ppm.
A NOAEL/fertility of 1000 ppm (equivalent to dosages of about 100 mg/kg bw/day) was derived from a study with oral exposure, and a NOAEC/developmental toxicity of 200 ppm (equivalent to dosages of about 205 mg/kg bw/d ay) was derived from a study with inhalation exposure.

Comment:
In Germany, vinyl acetate is assigned to the MAK-pregnancy category "D" denoting that the current database is not sufficient for final eval uation of developmental toxicity. However it is outlined that vinyl acetate was evaluated for repr oductive toxicity in one species (rat) already with negative results. If this latter outcome c ould be verified in additional species vinyl acetate could be assigned to category "C" deno ting that no risk for adverse developmental effects have to be expected for female work ers in compliance with the respective MAK value of 10 ppm.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 150 4.1.3 Risk characterisation

4.1.3.1 General aspects
Following oral and inhalation exposure of ra ts vinyl acetate is rapidly hydrolysed by carboxylesterases leading to the formation of acetic acid and acetaldehyde the latter of which is further converted into acetic acid by aldehyde dehydrogenases.

The in vivo uptake of vinyl acetate was measured in the isolated upper respiratory tract of rats (anaesthetised rat, unidirectional flow, 1 h-e xposure). Disappearance of vinyl acetate from the airstream was highest at the lowest exposure c oncentrations. Greater than 94% extraction was observed at vinyl acetate exposure concentrati ons of 76 ppm or below. With increasing exposure concentration (76 to 550 ppm), extracti on decreased progressively to about 40% and remained at this level up to concentrati on of approximately 2000 ppm. The impact on bloodflow extraction on vinyl acetat e deposition has been calculated by simulating vinyl acetate exposure in the absence of carboxylesterase ac tivity. It could be demonstrated, that blood flow extraction accounts for less than 15 % of total vinyl acetate deposition. Hence, 15 % inhalative uptake can be taken forward to ri sk characterisation of systemic effects by inhaltional exposure as a worst case scenario.
After oral administration of 297 mg/kg/bw 14 C vinyl acetate, 63 % of the applied radioactivity was excreted as metabolites in exhaled air, urine and faeces. Based on the fact that vinyl acetate can be metabolized in the upper GI tr act epithelium it can be assumed, that a considerable extent of metabolism takes place presystemically which is supported by an oral PBPK model. This model led to the conclu sion, that clearance of vinyl acetate and its metabolites into the systemic circulation woul d be negligible. Hence, 63 % absorption would represent an overestimation of systemically av ailable amounts of vinyl acetate. However, the PBPK model developed for oral vinyl acetate exposure did not include systemic components and furthermore, the model was developed in the absence of valid data for carboxylesterases in animal and human tissues. Based on the fact, that carboxylesterase activity in the GI tract is lower compared to that in nasal tissues, 50 % absorption can be assumed as a worst case for systemically available amounts of vinyl acet ate after oral uptake. However, no clear assumptions can be made for systemica lly available metabolites of vinyl acetate (acetaldehyde, acetic acid).
There are no valid quantitative data on the syst emic bioavailability of vinyl acetate and its metabolites following dermal exposure. However, based on an acute dermal study in rabbits and based on the fact that carboxylesterase activ ities are lower in skin compared to nose or oral cavity, it can be assumed that systemic bioavailablility of vinyl acetate and/or vinyl acetate-derived metabolites is higher after derm al exposure when compared to oral or inhalative exposure. Based on the currently ava ilable data 90 % dermal absorption should be taken forward to the risk characterisation.
Research on human and rat nasal respiratory a nd olfactory tissue with whole turbinates in vitro has shown that rat nasal respirator y carboxylesterase activity was about 3-fold higher than those of humans. Rat respiratory aldehyde dehydrogenase activity was about twice that of humans. Activities of the rat olfactor y enzymes (carboxylesterase and aldehydeR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 151 dehydrogenase) were about equivale nt to those of humans. The K m

values for both enzymes are not different between the two species. Al dehyde dehydrogenase activities determined in whole nasal tissue homogenates from mouse, rat, hamster and guinea pig showed significantly different ratios V max /K m

for the various species indicating the existence of species differences.
To provide validation data for the applica tion of a physiologically based pharmakokinetic (PBPK) model in humans, controlled human exposur es to vinyl acetate concentrations of 1, 5 and 10 ppm were conducted (5 volunteers). Data from ion trap mass spectrometry measurements of labelled vinyl acetate and la belled acetaldehyde were compared with the predictions of the human nasal model. For th e vinyl acetate data a good fit was demonstrated (r = 0.9). The quality of the acetal dehyde data fit is less (r = 0.6) than that of vinyl acetate. The results show that the human nasal model predicts the experimental observations with regard to vinyl acetate concentrations and the acetaldehyde washout in the airstream of human nasopharyngeal cavity in a concentration range from 1 to 10 ppm. Uncertainties of the model consist in the enzyme kinetic data used to parameterise the model. Nevertheless, according to the sensitivity analysis the modelled data can be taken for risk characterisation.
The results of PBPK modeling are taken fo rward for consideration on the appropriate adjustment factors. As vinyl acetate is acting locally, a systemic metabolism has not to be considered which reduces the interspecies f actor from 10 (default) to 2.5. Remaining uncertanties in toxicodynamic differences ar e recognized, i. e. humans could be more sensitive than rats towards local toxicity of vinyl acetate metabolites which could not be excluded due to the lack of (primarily human ) data. Thus, for risk charaterization an interspecies adjustment factor of 2.5 is establishe d. Concerning intraspecies variability the same consideration as for interspecies extrapolation applies. No systemic metabolism has to be taken into consideration, reducing the intraspecies adjustment factor to 2.5.
Vinyl acetate exhibits low acute toxicity by the oral and dermal routes, but acute inhalation toxicity is to be classified as harmful accordi ng to EU criteria. The oral LD50 for rats is found to about 3500 mg/kg body weight. Acute dermal t oxicity is reported for rabbits to exceed 7400 mg/kg. However, acute inhalation toxicity is characterised by a LC50 value of 15.8 mg/l/4 hours for rats. In a scarcely documente d study an LC50 value of 14.1 mg/l/4 hours is mentioned.
Except a general notice from occupationa l use no substantiated human data on irritation/corrosion caused by vinyl acetate are available. The pure substance shows mild irritation to skin and eyes. Acute inhalation test s with rats demonstrated severe irritation to the respiratory system (R 37). Vinyl acetate doe s not show corrosive properties after a single skin contact of not more than 4 hours.

There is no information available on skin sens itization in humans. No cases of sensitization from the handling of vinyl acetate in the workplace have been reported in the last years. There are no reports on allergic contact dermatitis by vinyl acetate from routine patch testing or experimental studies in man. Results from an animal skin sensitization study (Buehler Test) showed a moderate skin sensitizing potential of vinyl acetate (commercial grade). In a Local Lymph Node Assay an increased stimulation index was determined with 5 and 10 % vinyl acetate solutions but not at highe r concentrations. Thus, vinyl acetate is not devoid of a skin sensitising potential. However, the phrase R 43 is not warranted. Direct information on respiratory se nsitization from studies in humans is lacking.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 152 The major toxic effects after prolonged inhalati on of vinyl acetate in experimental animals were lesions of the surface epithelium of the upper and lower respiratory tract. Degeneration, regenerative/reparative processes, inflammation, hyperplasia and metaplasia were noted in the nasal mucosa. They were most pronounced in the olfactory epithelium occurring at 200 ppm in rats and mice during and at th e end of a 2-year exposure period. Lesions of the respiratory epithelium were seen in mice exposed to 600 ppm during and at the end of 2 years, whereas rats demonstrated lesions at this site only at a high concentration of 1000 ppm (4 week study). Characteristic alterations of the larynx and trachea of mice in the 600 ppm groups were hyperplasia and metaplasia along with desquama tion and fibrosis in the trachea. Similar changes of the bronchial and bronchiolar airways were reported for rats and mice at this concentration at the end of the 2-year exposur e period. In addition, clinical signs of nonspecific toxicity and irritation were evident, but no relevant toxic effect on any organ could be identified. From the 2-year studies, the NOAEC fo r local toxic effect on the respiratory tract was 50 ppm (178.5 mg/m3) in rats and mice. Ba sed on growth retardation in rats of the 600 ppm groups and mice of the 200 ppm groups, the NOAEC for systemic toxicity was considered to be at 50 ppm (mice 178.5 mg/m 3 ).
No specific organ toxicity was recorded after repeated oral administration of vinyl acetate with drinking water to rats and mice. A s ubchronic 13-week study revealed a slight (nonsignificant) reduction of food consumption and gr owth retardation in male rats at 5000 ppm (684 mg/kg bw/d). As NOAEL for systemic eff ects the value of 684 mg/kg bw/d (male rat) will be used in the risk characterisation.

Vinyl acetate is negative in bacterial mutagenicity tests. In mammalian cell cultures various cytogenetic e ffects were induced in the absence of S-9 mix (chromosomal aberrations, micronuclei, SC E) and in the presence of S-9 mix (SCE; chromosomal aberrations and micronuclei not an alysed with S-9 mix). The lowest positive concentrations ranged from 0.1 to 0.2 mmol/l. A positive mouse lymphoma assay is in line with these results, but it cannot be deduced whet her the positive effect is due to chromosomal or to gene mutations (no colony sizing). Mammalian cell culture investigations on DNA strand breaks (DSB) and DNA protein corsslinks (DPX) were negative (DSB), or extremely high concentrations were needed for positive effects (DPX). Very few reliable data are available on the in vivo mutagenicity of vinyl acetate. A weak induction of micronuclei in mouse bone marrow cells was clearly limited to intraperitoneal doses in the LD50 range (1000 and 2000 mg/kg) . In rats no induction of micronuclei was observed in spermatids (screening assay with intraperitoneal doses up to 1000 mg/kg). Further tests on induction of micronuclei or chromosomal aberrations were of too low reliability. Also in an SCE test with rats positive eff ects were weak and limited to high and probably highly toxic intraperitoneal doses (370 and 470 mg/kg). Such weak increases in SCE frequencies may well be induced by unspecific effects on the cell cycle. No specific DNA binding was observed in rat livers after inhalation or oral administration. Induction of sperm abnormalities in mice again was limited to doses in the toxic range. Furthermore, it is not specific for mutagens.
No clear conclusion can be drawn from a human study on the possible induction of chromosomal aberrations in workers exposed to vinyl acetate.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 153 Genotoxicity data on vinyl acetate metabolites are in line with the hypothesis that vinyl acetate genotoxicity is mediated by acetalde hyde. The genotoxicity of acetaldehyde is possibly limited to an overloading of defence mechanisms. Altogether, vinyl acetate has a mutagenic poten tial, which is preferentially expressed as clastogenesis. The data on in vivo genotoxicity are difficult to interpret, si nce their majority is of low reliability, or the effects are not specific to mutagenicity. The most important effect, a weak induction of micronuclei in mouse bone marro w, is limited to intraperitoneal doses of high toxicity. Therefore, it is unlikely that th e genotoxic potential of vinyl acetate is expressed in germ cells in man. However, genotoxic effects locally in directly exposed tissues (site of first contact) cannot be excluded; the occurrence and strength of the effects will be dependent on the metabolic capacity of the directly exposed tissue. No classification of vinyl acetate in terms of germ cell mutagenicity is proposed.

In cancer studies, vinyl acetate inhalation induced an increased number of nasal tumors (mainly papillomas and squamous cell carcinomas) in various regions of the nasal mucosa of rats. The total incidence was significantly in creased at a concentration of 600 ppm (2142 mg/m 3 ) but a single papilloma already develope d at 200 ppm. No significant tumor response was seen in a mice cancer bioassay. Occasiona lly single squamous cell tumors occurred at other sites of the respiratory tract in rats and mice.
Oral cancer studies were also positive. Signi ficantly increased incidences of benign and malignant squamous cell tumors in the oral cavity in rats and mice, in the esophagus and forestomach in mice were observed in 2-y ear drinking water studies at vinyl acetate concentration of 10000 ppm (dose ranges in rats 364-1062 mg/kg bw/d, in mice 800-2185 mg/kg bw/d). Similar results were found in another non-guideline conform cancer study on two generations of mice treated orally with 5000 ppm vinyl acetate in the drinking water (780 mg/kg bw/d). Higher rates of tumors were noted in the oral cavity, tongue, esophagus, forestomach (squamous cell carcinoma at all sites) as well as in the glandular stomach.
Vinyl acetate is considered as a threshold carcinogen because it is thought that carcinogenic action affects the site of first contact only a hi gh concentrations. Cytotoxicity was assumed as one underlying mode of carcinogenesis in the olfactory mucosa. The assumption was thought to be supported by consistent dose-respons e and time-response relationships between cytotoxic effect and tumor growth. No cytotoxi city as a prerequisite of tumor development was identified for the other tumor sites, the non-olfactory regions and the upper gastrointestinal tract. However, increases in cell proliferation comb ined with increased formation of DNA adducts were only seen a high c oncentrations of vinyl acetate. Both effects are considered to be mediated by acetaldehyde that accumulates intracellularly when the physiological balance of intracellular formati on and detoxification is disrupted above a certain, albeit unknown concentration of acetaldehyde . Instead, the most sensitive effects, the cytotoxicity of the olfactory region for the inhalation route (NOAEC 50 ppm), and the tumors of the upper gastrointestinal tract for the oral route (LOAEL 400 ppm), are recommended for risk characterisation.
No adequate data from human experience are available. Based on the carcinogenic potential of vinyl acetate in two animal species and at th e inhalative and oral route and the absence of reliable human data the substance might pose a cancer risk for humans. Carcinogenicity is thought to act via a secondary mechanism a nd the concern may only be relevant above threshold concentrations.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 154 Vinyl acetate was shown to have marginal infl uences on reproduction in animal studies only at oral exposure levels that produced certain signs of general toxicity. Distinct reproduction related adverse effects of vinyl acetate were not evidenced from a two generation study on rats with drinking water concentrations of up to and including 1000 ppm (NOAEL, equivalent to a dosage of 100 mg/kg bw/d). No embryo-/fetotoxic or teratogenic effects were observed in an oral study on rats for dose levels up to and including 5000 ppm vinyl acetate. A NOAEL/fertility of 1000 ppm (equivalent to about 100 mg/kg bw/d) was derived. Fetotoxic effects, revealed during inhalation exposure to rats, were confined to high dose levels ( 1000 ppm) only, where severe maternal toxicity was observed. A NOAEC for developmental toxicity of 200 ppm (corresponding to 205 mg/kg bw/d) was established from this study.

4.1.3.2 Workers

4.1.3.2.1 Introductory remarks
For occupational risk assessment of vinyl acetate the MOS approach as outlined in the revised TGD is applied. This occupational risk assessm ent is based upon the toxicological profile of vinyl acetate (chapter 4.1.2) and the occupati onal exposure assessment (chapter 4.1.1.2). The threshold levels identified in the hazard assessmen t are taken forward to this occupational risk assessment.

Systemic availability for different routes of exposure
Measurement at isolated upper respiratory tract of rats of in vivo uptake of vinyl acetate demonstrated, that blood flow extraction account s for less than 15 % of total vinyl acetate deposition (see chapter 4.1.2.1). Hence, 15 % inhalative uptake is taken as a worst case scenario for risk characterisation of systemic effects.
After oral administration of 297 mg/kg 14 C vinyl acetate, 63 % of the applied radioactivity was excreted as metabolites in exhaled air, urine and faeces. However, 63 % absorption would represent an overestimation of system ically available amounts of vinyl acetate (see chapter 4.1.2.1). 50 % absorption can be assume d as a worst case for systemically available amounts of vinyl acetate after oral uptake.
Based on an acute dermal study in rabbits and based on the fact that carboxylesterase activities are lower in skin compared to nose or oral cavity, it can be assumed that systemic bioavailability of vinyl acetate and/or vinyl acet ate-derived metabolites is higher after dermal exposure when compared to oral or inhalative exposure. Therefore 90 % dermal absorption is taken forward to the risk characterisation.
Altogether the following absorption percentages are used in the following risk assessment: 15% inhalative uptake for the assessment of sy stemic effects, 50% absorption after oral uptake of vinyl acetate and 90% absorption after dermal contact.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 155 Occupational exposure and internal body burden
In table 4.1.3.2.A the exposure levels of tables 4.1.1.2.4.A and 4.1.1.2.4.B are summarised and the route-specific and total internal body burdens are identified. Risk assessment for combined exposure requires the calculation of a total internal body burden; to this end the derived route-specific percentages for absorpti on are used (15% for inhalation and 90% for dermal exposure).

Table 4.1.3.2.A: Occupational exposure leve ls and internal body burden of vinyl acetate

Internal body burden of workers after repeated exposure Inhalation shift average Dermal contact shift average

Inhalation (1) Dermal (2) Combined Exposure scenario

mg/m 3 mg/p/d mg/kg/d mg/kg/d 1. Production and polymerisation in the chemical industry 3 (3) 42 (5) 0.6 0.064 0.54 0.60

a) polymerisation step (vinyl acetate monomer) 420 (6) 6 5.4 5.71 2.

Manufacturing of formulation s and products b) formulation step (vinyl acetate (co)polymer) 14.6 (3)

1.3 6) 0.02 0.31

0.018 0.33

3. Use of formulations and products containing residual vinyl acetate monomer 2.6 (4) 12.6 (6) 0.18 0.056 0.16 0.22

(1) based on the assumption of 15% inhalative absorption; breathing volume of 10 m 3 per shift (2) based on the assumption of 90% systemic ava ilability of vinyl acetate after dermal contact (3) reasonable worst case (4) worst case (5) EASE (90 % protection by suitable gloves) (6) EASE (without gloves)

MOS approach
The MOS approach for human risk characterisati on is described in detail in the TGD (Human Health Risk Characterisation, Final Draf t). The following chapter contains a short introduction to the MOS approach used. The ba sic principle of the MOS approach is a comparison of scenario-specific MOS values (the relationship between the experimental NOAEL respectively the adjusted starting point a nd the exposure level) with a reference MOS (product of various assessment factors).

MOS calculation and the adequate starting pointR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 156 Basically, MOS values are calculated as quotie nt of a relevant NOAEL from experimental animal testing or human studies and actual wo rkplace exposure levels. In specific situations, the MOS approach requires to convert the origin al NOAEL into an adequate starting point or corrected NOAEL previously to MOS calculation in order to be directly comparable to the exposure assessment. If the route of application in animal or human studies is different from the actual occupational exposure, the dose units of the experimental data should be converted to the dose unit of the exposur e data. Additionally, possible differences in bioavailability between routes, as well as possible differences in bioavailability between animals and humans should be accounted for the calculation of the co rrected NOAEL. If route-specific information on oral and inhalation absorption is not availabl e, the TGD recommends to assume a 50% oral absorption and a 100% inhalation absorption. For vinyl acetate 15% absorption after inhalation, 50% after oral exposure, and 90% ab sorption after dermal contact is assumed (see chapter 4.1.2.1).
For occupational risk assessment, the co rrected NOAEC for inhalation accounts for the difference of the standard respiratory volume (6.7 m3) and the respiratory volume for light activity (10 m3).

MOS values are calculated for different routes of exposure and for different toxicological endpoints. The routes of exposure specifically c onsidered in occupational risk assessment are exposure by inhalation and dermal contact.
In addition, for risk assessment of combined exposure (exposure by inhalation and dermal contact) an adequate NOAEL is derived from external NOAELs and specific information on route-specific absorption. For MOS calculation, th e adjusted internal starting point is divided by the internal body burden. Depending on route- specific exposure and absorption, inhalation exposure and/or dermal exposure may contribute to the internal body burden. With respect to the possible outcome of an assessment for combin ed risks, interest focuses on scenarios with conclusion ii at both exposure routes. Based on th eoretical considerations, combined exposure will not increase the most critical route-specific risk component more than twice.
Reference MOS
The MOS values calculated have to be compar ed with a reference MOS. The reference MOS is an overall assessment factor, which is obtained by multiplication of individual assessment factors. The Technical Guidance Document empha sises several aspects which are involved in the extrapolation of experimental data to the human situation. For these assessment factors, default values are recommended. It is importantto point out that any relevant substancespecific data and information may overrule the defined default values.
Interspecies extrapolation on the one hand is ba sed on allometric scaling (factor 4 for rats, factor 7 for mice, and factor 2.4 for rabbits). For remaining interspecies differences the TGD proposes an additional factor of 2.5. Inters pecies extrapolation conceptually might be considered to consist of a toxicokinetic a nd toxicodynamic phase. As to vinyl acetate PBPK models essentially describe the relationship be tween airborne concentration of vinyl acetate and intracellular acetaldehyde concentration. Howe ver, uncertainties of the model consist in the enzyme kinetic data used to establish th e model. Therefore, data on toxicokinetic and toxicodynamic outcome derived from the m odel should be taken with caution. For occupational risk characterisation an interspeci es factor of 2.5 is proposed (abutted at the default value for the remaining uncertainties of interspecies differences). For workers, anR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 157 adjustment factor for intraspecies differences of 5 is recommended. Ba sed on an evaluation of empirical data by Schneider et al. (2004) it is antic ipated that a factor of 5 will be sufficient to protect the major part of the worker population (about 95%). In the case of vinyl acetate PBPK results are available (see chapter 4.1.2.1 and 4.1.3.2), which suggest that the toxicodynamic portion of the default intraspecies factor (10 for the whole population, 5 for workers) remains as overall intraspecies factor since the toxicokinetic part (4) is not applied (no systemic metabolism as it is virtually impo ssible that vinyl acetate will reach the systemic circulation). The remaining uncertainties are c overed by application of a reduced adjustment factor for workers in the range of 1.25 and 2.5.
For chemical substances it is usually expect ed that the experimental NOAEL will decrease with increasing duration of application. Furthe rmore, other and more serious adverse effects may appear with prolonged exposur e duration. For duration adjustment, a default factor of 6 is proposed for extrapolation from a subacute to chronic exposure. The duration adjustment factor is lower (a factor of 2) for the tran sition from subchronic experimental exposure to chronic exposure. Since chronic studi es are available for vinyl acetate, a specific factor for duration adjustment of repeated dose toxicity is not necessary.
The TGD defines two further adjustment factors (uncertainty in route-to-route extrapolation and dose-response relationship including severity of effect). In specifi c cases these factors may be different from one. For vinyl acetate no further adjustment factors are used in the risk assessment.
Comparison of MOS and reference MOS
The MOS values for different toxicological endpoints and different exposure scenarios are compared with the substance- and endpoint-s pecific reference MOS. MOS values clearly above the reference MOS do not lead to concern, whereas MOS values that are clearly below the reference MOS are cause for concern. There may be various risk-related aspects which are not covered by default assessment factors. These additional qualitative aspects should be carefully considered when performing a risk assessment and should have adequate influence on finding of conclusions.
Critical Exposure Levels
In a parallel procedure, which gives identi cal but more direct results, the adjusted toxicological starting point is di rectly divided by the reference MOS. As a result, an exposure level (in mg/m3 or mg/kg/d) is identified, whic h may serve as a direct trigger for decisions when compared with the occupational exposure le vels. In the context of this risk assessment report this trigger value is called “critical e xposure level”. Concern will be expressed for scenarios with occupational exposure levels higher than the relevant “critical exposure level”.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 158 4.1.3.2.2 Occupational risk assessment

Acute toxicity

- Inhalation

LC 50 –values of 14.1 and 15.8 mg/l (4 h) were dete rmined in rats. No animals died at the lowest tested dose of 7 mg/l (4 h). Gross pat hology revealed no remarkable effects, but red and irritated extremities were observed as clinical signs.
Comparing the LC 50 -value of ca. 15,000 mg/m 3 and the concentration of 7,000 mg/m 3 without lethality with the highest expos ure concentration of 15 mg/m 3 (scenario 2, reasonable worst case) and the highest short-term exposure of 47 mg/m 3 (scenario 2) a relevant risk concerning acute toxicity is not expected under normal workplace conditions.
Conclusion ii)
There is at present no need for further info rmation and/or testing or for risk reduction measures beyond those which are being applied already.

- Dermal contact

The LD 50 in rabbits was 7,440 mg/kg (24 h, occl usive). At the lowest tested dose of 3,720 mg/kg no mortalities and no clinical signs were observed, but gross pathology revealed effects in liver, spleen, kidney and the lungs.
Comparing the LD 50 of 7,440 mg/kg and the dose of 3,720 mg/kg (no mortalities, but effects in different organs) with the highest dermal exposure of 6 mg/kg (scen ario 2a, use of vinyl acetate monomer) a relevant risk concerning acu te toxicity is not expected under normal workplace conditions.
Conclusion ii)
There is at present no need for further info rmation and/or testing or for risk reduction measures beyond those which are being applied already.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 159 - Irritation/Corrosivity
- Dermal/Eyes
A general notice from occupational use describes principally local irritant reactions of the skin, eyes and respiratory tract (information by the vinyl acetate industry, without further details, possibly only historical relevance).
Due to the only valid tests (RCC, 2003a and c) m ild irritation on the skin and eyes of rabbits were observed that do not warrant classification. Earlier studies of limited reliability indicated pronounced irritation or corrosion of skin after extended exposure periods.
All data were not substantive enough for a cl assification with the corresponding R-phrases. No concern for dermal or eye irritation at the workplace is expressed.
Conclusion ii)
There is at present no need for further info rmation and/or testing or for risk reduction measures beyond those which are being applied already.

Inhalation
According to chapter 4.1.2.3/4.1.2.4 vinyl acetat e has proven to cause severe irritation in the respiratory tract of rats. Additional informa tion on acute irritation can be obtained from chapter 4.1.2.6. Sprague-Dawley-rats were expos ed for 1, 5 and 20 days in an inhalation study (6 h/day, 5 days/week) to 0, 50, 200, 600, or 1,000 ppm (Bogdanffy et al., 1997). Following the single exposure of one day, rats of th e 600 and 1,000 ppm groups showed concentrationrelated minimal to moderate degeneration, necrosis and exfoliation of the olfactory epithelium. Additionally a minimal degeneration and necrosis in the respiratory epithelium occurred at 1,000 ppm. So the value of 200 ppm (corresponding to 710 mg/m 3 ) will be used as NOAEC, concerning local effects after short term inhalative exposure.

A MOS calculation would result in a value of about 79 mg/m 3 (inhalation starting point of 476 mg/m3 with the NOAEC of 710 mg/m 3 multiplied by 6.7/10 (activity-driven differences of respiratory volumes in workers) divided by a reference MOS of about 3 – 6 (intraspecies differences factor 1.25 – 2.5 and interspecies factor of 2.5).
Comparing the critical exposure level of 79 mg/m 3 with the highest exposure of 14.6 mg/m 3 (scenario 2) a relevant risk concerning irrita tion after inhalation is not expected under normal workplace conditions.

Conclusion ii)
There is at present no need for further info rmation and/or testing or for risk reduction measures beyond those which are being applied already.

4.1.3.2.B: Local effects after inhalative exposure to vinyl acetateR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 160 Acute exposure, Repeated exposure, Starting point for MOS calculation 476 mg/m 3 90 mg/m 3

Reference MOS 6 5.1 Critical exposure level 79 mg/m 3 17.6 mg/m 3Exposure (mg/m3)MOSConclusionsExposure(mg/p/d)MOSConclusions

1. Production and polymerization in the chemical industry 3 159 ii 3 30 ii

2. Manufacturing of formulations and products 14.6 33 ii 14.6 6 Borderlin e iii

Short-term exposure 47 10 ii

3. Use of formulations and products containing residua l vinyl acetate

monomer 2.6 183 ii 2.6 35 ii

Sensitization

Dermal contact
No cases of skin sensitization from the handling of vinyl acetate in the workplace have been reported in the last years.

Results from an animal skin sensitization st udy (Buehler Test) showed a moderate skin sensitising potential of vinyl acetate. In a Local Lymph Node Assay (LLNA) no positive stimulation responses were seen at concentr ations of 5% - 100%. However, the results obtained with this LLNA may not fully reflect the potential of concentrations >10%, since higher concentrations of vinyl acetate show in creasing volatility, due to decreased proportions of acetone/olive oil. Since the positive thres hold level was not exceeded in the LLNA, classification and labelling with R 43 is not warranted. No concern is expressed.
Conclusion ii)
There is at present no need for further info rmation and/or testing or for risk reduction measures beyond those which are being applied already.

InhalationR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 161 No information on respiratory sensitisation is ava ilable. However, in view of the fact that during all the years of use specific case reports have not been reported, vinyl acetate seems at least not to be a strong respiratory sensitizer in humans. For the time being no animal model is available which would be able to verify the question of respiratory sensitisation. In summary concern is not expressed.
Conclusion ii)
There is at present no need for further info rmation and/or testing or for risk reduction measures beyond those which are being applied already.

Repeated dose toxicity
Local effects

Inhalation
In a combined chronic toxicity and carcinoge nic study (Owen, 1988; Bogdanffy et al., 1994b) male and female Sprague Dawley rats and CD -1 mice were exposed by inhalation to vinyl acetate vapour in concentrations of 0, 50, 200, and 600 ppm (equivalent to 0, 178.5, 714, 2,142 mg/m 3 ) over a period of 2 years (6 hours/day, 5 days/week). Examinations on haematology, clinical chemistry, urinalysis and gross and microscopic abnormalities were performed on satellite groups at week 51 and 81 and on the end of the main study. In both species of each sex, vinyl acetate induced mo rphological nonneoplastic lesions in the nasal cavity of the 200 and 600 ppm groups and in the trachea (mice only) and in the lungs of the 600 ppm groups. Based on these findings the NOAEC for local effects on the respiratory tract was 50 ppm (180 mg/m 3 ). This NOAEC is taken as starting point for the risk assessment of local effects after repeated exposure.
The experimental NOAEC of 180 mg/m 3 is (1) adapted by a factor of 6/8 to account for differences between the experimental inhalati on duration of 6 hours per day and the average working day of 8 hours per day, and (2) is mu ltiplied by a factor of 6.7/10 for activity-driven differences of respiratory volumes in workers. This results in an adjusted inhalation starting point of 90 mg/m 3 (180 • 6/8 • 6.7/10)
The reference MOS accounts with the intraspecies differences with a factor of 1.25 – 2.5 (see chapter 4.1.3.2.1 reference MOS). The interspecies differences deal with a factor of 2.5 (the factor for allometric scaling is already im plicitly applied). Duration adjustment is not necessary, because a long term study is available.

This would result in a refere nce MOS of about 3 – 6 (5 • 1.25 – 2.5) and a critical exposure level of 15 to 30 mg/m 3 depending on how big the factor for intraspecies differences is dealt with. Comparing this range for a critical exposur e level of vinyl acetate with the OEL of 17.6 mg/m 3 (5 ppm) which was set by the Scientific Committee on Occupational Exposure Limits, the value is very close at the lower value of 15 mg/m 3 . For pragmatic reasons the occupational exposure value of 17.6 mg/m 3 (5 ppm), which was set by SCO EL (2005) is taken forward to this risk assessment. The SCOEL value corresponds to a reference MOS value of 5.1.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 162 The highest shift average value for inhalation is reported as 14.6 mg/m 3 for manufacturing of formulations and products of vinyl acetate in scenario 2. Compared with the OEL of 17.6 mg/m 3 the scenario reaches borderline. Conclusion iii is drawn for scenario 2 since there is the uncertainty concerning the reduction of the in traspecies factor. The other scenarios do not reach concern (for corresponding MOS values see table 4.1.3.2.B).
Conclusion iii)
There is a need for limiting the risks; risk reduction measures which are already being applied shall be taken into account.

Dermal contact
Dermal studies with repeated application are not available. Besides the tests described in chapter 4.1.2.4 only a general notice from occupa tional use describes principally local irritant reactions of the skin, eyes and respiratory tract.

The data demand no classification and are not substantiated enough for raising a concern for repeated dermal contact.
Conclusion ii)
There is at present no need for further info rmation and/or testing or for risk reduction measures beyond those which are being applied already.

Systemic effects
Distinct systemic effects after inhalation or oral ad ministration of vinyl acetate are not reported. The only indicator for systemic effects after repeated inhalation of vinyl acetate could be a decreased body weight gain observed in rats at 2,142 mg/m 3 (600 ppm) and in mice at 714 mg/m 3 (200 ppm) and above, observed in a combined chronic toxicity and carcinogenicity study (Owen, 1988; Bogdanffy et al., 1994b).

Inhalation
The combined chronic toxicity and carcinoge nicity study (Owen, 1988; Bogdanffy et al., 1994b, see above), which was used for the risk assessment of local e ffects after repeated inhalation serves also for the risk assessment of systemic effects. A decreased body weight gain, but no target organ toxicity, was observed in rats at 2,142 mg/m 3 (600 ppm) and in mice at 714 mg/m 3 (200 ppm) and above. This decrease may be associated to non-specific toxicity of vinyl acetate. It was interpreted to be attr ibuted to lower food and water consumption, but the 2-year study did not contai n any data on the consumption of water/food and the food efficiency. Based on the reduction of body we ight gain the NOAEC of 50 ppm (180 mg/m 3 ) of the mice is taken for the MOS calculation.
The derivation of the starting point and the refe rence MOS are identical with the values which are derived for carcinogenicity (values see under chapter carcinogenicity). The criticalR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 163 exposure level regarding systemic toxicity af ter repeated inhalation is identified as 17.6 mg/m 3 (90 / 5.1).
The highest shift average value for inhalation is reported as 14.6 mg/m 3 for manufacturing of formulations and products of vinyl acetate in scenario 2. Compared with the OEL of 17.6 mg/m 3 the scenario is a borderline case. Conclusi on iii is drawn for scenario 2 since there is the uncertainty concerning the reduction of the in traspecies factor. The other scenarios do not reach concern (for corresponding MOS values see table 4.1.3.2.C).
Conclusion iii)
There is a need for limiting the risks; risk reduction measures which are already being applied shall be taken into account.

Dermal contact
Dermal studies with repeated application are not available. Thus the studies with other routes of application are taken into account. A target or gan of systemic toxicity was not observed in the oral or inhalation studies. The systemic LOAEC of inhalation toxicity was defined by a decreased body weight gain, which was interpreted to be based on lower food and water consumption (see above). The central drinki ng water study in rats and mice over 13 weeks revealed no significant systemic effects up to the highest tested dose of 5000 ppm (684 - 810 mg/kg/day for rats; 281 - 285 mg/kg/day for mice).
Since a quantitative risk assessment regarding rep eated dermal contact is connected with high uncertainties regarding systemic availability, r oute-to-route extrapolation and the missing of distinct systemic effects, only a rough estimation is done. For this the following considerations regarding the assessment of re peated dermal exposure are taken into account: Neat vinyl acetate (1 mg/m 3 ) would evaporate within about 10 seconds from skin under usual working conditions of non occlusiv e exposure. From the experimental data there is no distinct systemic effect described (highest tested dose of 810 mg/kg/day fr om the drinking water study).
Compared with the highest dermal exposure of 6 mg/kg (scenario 2a, use of vinyl acetate monomer) there seems to result no concern for repeated dermal contact.
Conclusion ii)
There is at present no need for further info rmation and/or testing or for risk reduction measures beyond those which are being applied already.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 164 Combined exposure

Besides scenario 2 no further scenario reaches concern.
Conclusion iii)
There is a need for limiting the risks; risk reduction measures which are already being applied shall be taken into account

Table 4.1.3.2.C: Repeated dose toxic ity, systemic effects of vinyl acetate

Inhalation Dermal Combined

Starting point for MOS calculation 90 mg/m3 no quantitative calculation, see text no quantitative calculation, see text

Reference MOS 5.1 - -

Critical exposure level 17.6 mg/m3 -- -Exposure(mg/m3)MOSConclusionExposure(mg/kg/d)MOSConclusionInternal body burden(mg/kg/d)MOSConclusion

1. Production and polymerisation in the chemical industry 3 30 ii 0.6 ii 0.6 ii

a) polymerisatio n step (vinyl acetate monomer) 6 ii 5.71 iii 1)2. Manufacturing of formulation s and products b) formulation step (vinyl acetate (co)polymer) 14.6 6.2 Border line iii

0.02 ii 0.33 iii 1)

3. Use of formulations and products containing residual vinyl acetate monomer 2.6 34.8 ii 0.18 ii 0.22 ii

(1) conclusion iii already results from inhalation exposure

MutagenicityR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 165 Vinyl acetate is negative in bacterial mutagenicity tests.
The substance has a mutagenic potential, which is preferentially expressed as clastogenesis. The data on in vivo genotoxicity are difficult to interpret, since their majority is of low reliability, or the effects are not specific to mu tagenicity. The most important effect, a weak induction of micronuclei in mouse bone marrow, is limited to intraperitoneal doses of high toxicity.
It is unlikely, that the genotoxic potential of vi nyl acetate is expressed in germ cells in man, because vinyl acetate genotoxicity is limited to toxic doses. For vinyl acetate a threshold mechanism of action is assumed.
Conclusion ii)
There is at present no need for further info rmation and/or testing or for risk reduction measures beyond those which are being applied already.

Carcinogenicity
Regarding the carcinogenicity of vinyl acetate, no adequate human data base is available. Long-term inhalation and oral administration of vinyl acetate in experimental animals produced tumors at the primary site of exposure, the surface epithelium of the respiratory tract and the upper gastrointestinal tract. After inhalation a tumor response to vinyl acetate exposure was seen at 600 ppm in rats (Bogdanffy et al., 1994b), for the or al route an increase of tumor rates has been observed at 10,000 ppm (male rat 442 mg/kg/day, female rat 575 mg/kg/day, Umeda et al., 2004a).
Vinyl acetate carcinogenicity is assumed to be mediated by the metabolic product acetaldehyde. Based on the nonlinear kinetics of intracellular aldehyd dehydrogenase activity there is a marked increase of intracellular acet aldehyde only at high con centrations of vinyl acetate. With reference to this non-linear dose response relationship for the critical metabolite acetaldehyde risk assessment is performed with the MOS approach.

Inhalation
The study, which serves as key study for the risk assessment of carcinogenicity of vinyl acetate is the combined chronic toxicity and carcinogenic study from Owen (1988) and Bogdanffy et al (1994b), which was already taken for the risk assessment of repeated dose toxicity. Exposure-related tumor response was obs erved in the nasal cavity of rats at the highest concentration of 600 ppm. A total of 11 nasal cavity tumors were evident in 7 males and 4 females, classified as papilloma and/or carcinoma cell types (see table 4.1.2.8.A). In the intermediate group (200 ppm) one single tumor (b enign papilloma) was found in a male rat. No respiratory tract tumor was seen in the control and low dose groups (50 ppm) except for a single adenoma of the lung in a control fe male. From this study a NOAEC of 50 ppm (180 mg/m 3 ) is derived and used as a threshold concentration.
The experimental NOAEC of 180 mg/m 3 is (1) adapted by a factor of 6/8 to account for differences between the experimental inhalati on duration of 6 hours per day and the averageR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 166 working day of 8 hours per day, and (2) is mu ltiplied by a factor of 6.7/10 for activity-driven differences of respiratory volumes in workers. This results in an adjusted inhalation starting point of 90 mg/m 3 (180 • 6/8 • 6.7/10).

The reference MOS would account w ith the intraspecies differences with a factor of 1.25 – 2.5 (see chapter 4.1.3.2.1 reference MOS). The interspecies differences would deal with a factor of 2.5 This would altoge ther result in a reference MOS of about 3 to 6. The critical exposure level regarding carcinogenicity would then lie between 15 and 30 mg/m 3 (90 / 6 or 3), depending on how big the intraspecies di fferences are dealt with. Looking at the recommendation of the Scientific Committ ee on Occupational Exposure Limits, the committee decided in 2005 to set an OEL for vinyl acetate of 17.6 mg/m 3 (5 ppm). This value is in the same order than the lower value of 15 mg/m 3 . For pragmatic reasons the occupational exposure value of 17.6 mg/m 3 (5 ppm), which was set by SCO EL (2005) is taken forward in this risk assessment. The SCOEL value corresponds to a reference MOS value of 5.1.
For scenario 2 (manufacture of formulati ons and products), the exposure is 14.6 mg/m 3 . Since there is the uncertainty concerning the reduction of the intraspecies f actor and the mode of action for carcinogenesis for this borderline s cenario conclusion iii is drawn. The other scenarios are out of concern. For corresponding MOS values see table 4.1.3.2.D.
Conclusion: iii)
There is a need for limiting the risks; risk reduction measures which are already being applied shall be taken into account.

Dermal contact
Dermal carcinogenicity studies are not availabl e. An oral drinking water study with rats (Umeda et al., 2004a) showed higher incidences of tumor rates at the local site of contact: squamous cell carcinoma in the the oral cavity, esophagus, and stomach, which were considered to be treatment related.
Vinyl acetate should be able to reach vivid skin cells and a potential to induce skin tumours cannot be excluded. A quantitative approach is not possible, since a quantitative route to route extrapolation of local effects is generally not performed. For risk characterisation purposes it should be further considered, that the high vapour pressure of vinyl acetate leads to reduced retention time on skin absorption.
The highest dermal exposure value (6 mg/kg/da y) was estimated for the use of pure vinyl acetate during manufacture of formul ations and products (scenario 2a). The magnitude of this exposure value is also based on the knowledge, th at gloves are not regularly worn in small and medium-sized enterprises. The other scenario s have exposure values at least one order of magnitude below (<0.6 mg/kg/day). This is due to a high acceptance of gloves in the largescale chemical industry (scenario 1) and the f act, that vinyl acetate is only available as a residual monomer (< 2 – 3000 ppm) in scenario 2b and 3.

Based on this information and the fact that especially the high doses led to a significant carcinogenic response in experimental studies, s cenario 2a with the highest exposure due to non-effective skin protection is considered to be associated with a significant risk, whichR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 167 should require further specific measures. The other scenarios (scenario 1, 2b, 3) are considered to be of lower concern and a low risk level is assumed.

Concern for scenario 2a (manufacturing of fo rmulations and products with the vinyl acetate monomer, see table 4.1.3.2.D).
Conclusion: iii)
There is a need for limiting the risks; risk reduction measures which are already being applied shall be taken into account

Combined exposure
Concern was already expressed for scenario 2a af ter dermal contact. Thus Scenario 2a reaches also concern for combined exposure.
Because of the lower exposure values for scenarios 1, 2b and 3 no concern is expressed.
Conclusion: iii)
There is a need for limiting the risks; risk reduction measures which are already being applied shall be taken into accountR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 168 Table 4.1.3.2.D: Carcinogenicity of vinyl acetate

Inhalation Dermal Combined

Starting point for MOS calculation 90 mg/m3 no quantitative calculation, see text no quantitative calculation, see text

Reference MOS 5.1

Critical exposure level 17.6mg/m3Exposure(mg/m3)MOSConclusionExposure(mg/kg/d)MOSConclusionInternal body burden(mg/kg/d)MOSConclusion

1. Production and polymerisation in the chemical industry 3 30 ii 0.6 ii 0.6 ii

a) polymerisatio n step (vinyl acetate monomer) 6 iii 5.71 iii (1)2. Manufacturing of formulation s and products b) formulation step (vinyl acetate (co)polymer) 14.6 6.2 Border line iii

0.02 ii 0.33 iii 1)

3. Use of formulations and products containing residual vinyl acetate monomer 2.6 34.8 ii 0.18 ii 0.22 ii

(1) conclusion iii already results from i nhalation and/or dermal exposure

Reproductive toxicity

Fertility impairment and developmental toxicity
With respect to toxicity for reproduction no human data are available.
Distinct reproduction related adverse effects of vinyl acetate are not reported from a two generation drinking water study with rats for concentrations including 1000 ppm.
The developmental toxicity of vinyl acetate has been investigated in rats via oral (drinking water) and inhalation exposure routes duri ng organogenesis. No embryo/fetotoxic or teratogenic effects were observed for the oral route of administration at drinking waterR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 169 concentrations including 5000 ppm. Fetotoxic eff ects, revealed during inhalation exposure, were confined to high dose levels only, where severe maternal toxicity was observed.
In addition, any specific teratogenic potential a nd/or impairment of embryo/fetal development are not indicated from the same data. Theref ore no MOS calculation is performed for this endpoint.

Conclusion ii
There is at present no need for further info rmation and/or testing or for risk reduction measures beyond those which are being applied already.

4.1.3.2.3 Summary of conclusions for the occupational risk assessment
Table 4.1.3.2.E indicates the toxicological e ndpoints of concern for vinyl acetate. Concern results for carcinogenicity after dermal exposure. For the other endpoints no concern is expressed. Table 4.1.3.2.E: Endpoint-specific overall conclusions

Toxicological endpoints General conclusion Exposure Scenarios
inhalation ii
dermal ii Acute toxicity
combined ii
dermal ii eye ii Irritation/ Corrosivity acute respiratory tract ii
skin ii Sensitisation respiratory ii inhalation, local iii 2a inhalation, systemic iii 2a dermal, local ii dermal, systemic ii Repeated dose toxicity

combined, systemic iii 2a Mutagenicity ii
inhalation iii 2a
dermal iii 2a Carcinogenicity
combined iii 2a (1)R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 170 inhalation ii
dermal ii Reproductive toxicity
combined ii
(1) conclusion iii already results from inhalative and/or de rmal exposure, therefore no specific concern for the combined exposure scenario is indicated

Risk estimation is mainly based on animal i nhalation studies and oral studies. The following absorption percentages are assumed for the di fferent exposure ways: 15% inhalative uptake for the assessment of systemic effects, 50% ab sorption after oral uptak e of vinyl acetate and 90% absorption after dermal contact. The most pronounced effects of vi nyl acetate are local effects after repeated inhalation contact and carcinogenicity. The value of 17.6 mg/m 3 designates the critical exposure level as well for carcinogenicity as repeated dose toxicity after inhalation. Following inhalation, the substance is rapidly hydrolysed by carboxylestera ses leading to the formation of acetic acid and acetaldehyde which is further converted into acetic acid. At higher concentrations of vinyl acetate the capacity of the intracellular en zymes is not big enough to oxidize all of the generated acetaldehyde. Thus, at high vinyl acet ate concentrations, non-physiologically high concentrations of acetaldehyde are produced. This intermediate, develops adverse effects at non-physiologically high concentrations, which re sult in the formation of tumors at the exposed tissue. Because of the carcinogenic effect s only occur at the site of first contact at high concentrations of vinyl acetate, the substa nce is considered as a threshold carcinogen. On the background of cancer risks and repeated dos e toxicity (local and systemic effects), air concentrations of vinyl acetate at the workplace should be controlled to a level in the range of 17.6 mg/m 3 (critical exposure level). However, scen ario 1 and 3 of the inhalation exposure scenarios, specified in this report describe lowe r exposure values and are thus out of concern. Scenario 2 (manufacture of formulations and products ), with an exposure value of 14.6 mg/m 3 is a borderline case. Since there is the uncertain ty concerning the reduction of the intraspecies factor and the mode of action for carcinogenesis for this borderline scenario conclusion iii is drawn for repeated dose toxicity and carcinogenesis. Skin contact of vinyl acetate should be reduced in scenario 2a (manufacturing of formulations and products, vinyl acetate monomer), even if evaporation of the substance reduces the contribution of dermal exposure.

4.1.3.3 Consumers
Following the exposure assessment there is no di rect exposure of the consumer to vinyl acetate besides of the release of monomers from polymers. Overall exposure to vinyl acetate occurs mainly via inhalation due to emissions from carpets, paints and adhesives. For comparison with acute effects, the estimate for short-term exposure to concentrations of a about 1 mg/m3 from carpets will be used. With re gard to chronic effects, the concentration of 0.036 mg/m3 for long-term exposure will be used resulting in an exposure of 9.2 μg/kg bw/d for men, of 4.6 μg/kg bw/d for women, and of 18 μg/kg bw/d for children. The inhalation exposures numbers representing residual monomer ic vinyl acetate still overestimate realisticR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 171 chronic exposure because according to the bioc hemical data remarkable amounts of vinyl acetate will be metabolized rapidly to acetaldehyde in the olfactory and respiratory epithelium (see chapter 4.1.2.1) thus only very small am ounts of vinyl acetate will reach the systemic circulation. Furthermore, the consumer may be exposed to vinyl acetate by using hair setting lotions (1 μg/kg bw/d) by the dermal route and by migration of the substance from plastics coming into contact with foods via oral route. Since this exposure scenario is regulated (see chapter 4.1.1.3) there is no need for MOS calculation.

Acute Toxicity
Following the exposure assessment, consumers ar e not expected to be exposed to vinyl acetate in the range of doses which can be derive d from acute oral or dermal toxicity figures based on animal LD 50 values (oral and de rmal: > 3500 mg/kg body weight). Therefore the substance is of no concern in relation to acute oral or dermal toxicity.
The inhalation route of exposure should be of no concern, because in rats vinyl acetate has demonstrated LC50 values of > 14 mg/l/4h. For short-term exposure from carpets concentrations of 0.001 mg/l have been calculated

.

Conclusion ii)
There is at present no need for further info rmation and/or testing or for risk reduction measures beyond those which are being applied already.

Irritation/Corrosivity
Vinyl acetate causes only mild irritation to the skin and eyes of rabbits, but causes severe irritation in the respiratory tract of rats. Hu man data on irritation/corrosivity caused by vinyl acetate are not available.
Following the exposure assessment it can be a ssumed that consumers are exposed only to such concentrations which are far below the effective concentrations.

Conclusion ii)
There is at present no need for further info rmation and/or testing or for risk reduction measures beyond those which are being applied already.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 172 Sensitization

Data obtained from a Buehler Test demonstrat e that vinyl acetate (commercial grade) is a moderate skin sensitizer. The results of a Lo cal Lymph Node Assay confirm the weak to moderate effects in the Buehler Test, but do not warrant classification and labelling.
No reports of allergic contact dermatitis cause d by vinyl acetate from routine patch testing or experimental studies in man are available. Fu rthermore, no direct information is available from studies in humans on respiratory sensitizati on. In view of the widespread occupational use, the absence of any reports suggests that vinyl acetate may not be a respiratory sensitizer.
Conclusion ii)
There is at present no need for further info rmation and/or testing or for risk reduction measures beyond those which are being applied already.

Repeated dose toxicity/Non-neoplastic lesions
Following the exposure assessment there may be chronic exposure to vinyl acetate resulting from release of residual monomers out of polymers.
The major toxic effects after prolonged inhalati on of vinyl acetate in experimental animals were lesions of the surface epithelium of the upper and lower respiratory tract. Degeneration, regenerative/reparative processes, inflammation, hyperplasia and metaplasia were noted in the nasal mucosa as non-neoplastic effects. These effects were most pronounced in the olfactory epithelium occurring at 200 ppm in rats and mice during and at the end of a 2-year exposure period. Lesions of the respiratory epithelium were seen in mice exposed to 600 ppm during and at the end of 2 years, whereas rats dem onstrated lesions at this site only at a high concentration of 1000 ppm (4 week study). Charact eristic alterations of the larynx and trachea of mice in the 600 ppm groups were hyperplasia and metaplasia along with desquamation and fibrosis in the trachea. Similar changes of the bronchial and bronchiolar airways were reported for rats and mice at this concentration at the end of the 2-year exposure period. In addition, clinical signs of non-specific toxicity and irritation were evident, but no relevant toxic effect on any organ could be identified. The NOAEC for local toxic effects on the respiratory tract of 50 ppm (178. 5 mg/m3) was derived from the 2-year studies on rats and mice. Based on growth retardation in rats of the 600 ppm groups and due to hunched posture in mice of the 200 ppm groups, the NOAEC for syst emic toxicity was considered at 50 ppm for mice (178.5 mg/m 3 ) and 200 ppm for rats (714 mg/m3).
No specific organ toxicity was recorded after repeated oral administration of vinyl acetate with drinking water to rats and mice. A s ubchronic 13-week study revealed a slight (nonsignificant) reduction of food consumption and gr owth retardation in male rats at 5000 ppm (684 mg/kg bw/d).
For the decision on the appropriateness of MOS, the following aspects regarding the critical effect as well as exposure have been considered and taken into account:R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 173 - overall confidence in the database
The data taken into account for performing the ri sk characterization have been evaluated with regard to their reliability, relevance and comp leteness according to section 3.2 of the TGD. The data were published in peer reviewed jour nals or submitted to the Competent Authority in private reports being adequately detailed a nd in accordance with internationally recognized guidelines and to GLP.
The findings of all studies are not contradictor y so that the judgement can be based on the database (cf. 4.1.2.6 and 4.1.2.8).

There are no reasons to assume limited confidence.

- uncertainty arising from the variability in the experimental data
The studies cited above consistently indicated degeneration of the nasal epithelium in several studies on rats and mice. From a well perfor med 2-year inhalation study on rats and mice a NOAEC for local effects of 178 mg/m 3 (50 ppm) was derived and the results were in conformity with the findings of the other studies.

- intra- and interspecies variation
The results of PBPK modeling are taken fo rward for consideration on the appropriate adjustment factors. As vinyl acetate is acting locally, a systemic metabolism has not to be considered, which reduces the interspecies f actor from 10 (default) to 2.5. Remaining uncertanties in toxicodynamic differences ar e recognized, i. e. humans could be more sensitive than rats towards local toxicity of vinyl acetate metabolites which could not be excluded due to the lack of (primarily human ) data. Thus, for risk charaterization an interspecies adjustment factor of 2.5 is establishe d. Concerning intraspecies variability the same consideration as for interspecies extrapolation applies. No systemic metabolism has to be taken into consideration, reducing the intraspecies adjustment factor to 2.5.
- the nature and severity of the effect
The main effects considered as „critical effects“ are the degenerative lesions of the olfactory mucosa (irreversible, serious health effect).

There are no reasons to assume that the effects shown in the animal experiments are limited to the species tested, thus being not of relevan ce for humans. Because of the seriousness of the effect there is concern, which has to be expressed in the magnitude of the MOS.

- dose-response-relationship
In rats as well as mice no steep dose-response-re lationship is observed for the irritation effects at the olfactorium. At the LOAEC (714 mg/m 3 , 200 ppm) only minimal to slight changes in the olfactory epithelium were observed.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 174 There is no reason to assume concern which has to be expressed in an increased MOS taking into account the exposure level.

- differences in exposure (route, duration, frequency and pattern)
Following the exposure assessment, the consumer may be exposed to vinyl acetate via inhalation, whereas oral and dermal exposures are assumed of minor importance.

a) Inhalation route

The NOAEC used for the discussion of the MOS re garding exposure from carpets is derived from a 2-year inhalation study on rats. Because vinyl acetate acts primarily at the nasal cavity, systemic effects have not been considered. Moreover, the NOAEC for systemic effects was considered to be 714 mg/m 3 for rats and 178 mg/m3 for mice in the same study.

b) Oral route
The oral route is not relevant for risk characterization (see introductory remarks).

c) Dermal route
Following the exposure assessment, the consumer may be exposed dermally to vinyl acetate via usage of hair setting lotions. The estimated dermal body burden (1 μg/kg bw/d) with an assumed absorption of 100% is compared with a NOAEL from an oral 90-day study due to the lack of a dermal study.

There are no reasons to assume that special c oncern can be derived from this procedure nor from the available toxicokinetic information (concerning absorption via different routes was set with 100%).

- the human population to which the quantitative and/or qualitative information on exposure applies
Following the inhalation exposure there is no reas on to assume a special risk for elderly, children or other people suffering from special diseases.

- other factors
There are no other factors known requiring a peculiar margin of safety.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 175 MOS for
Inhalation exposure scenario
Long-term exposure to 0.036 mg/m3 vinyl acetat e is assumed to result via emission from carpets. The margin of safety for non-neoplastic effects between the
measured exposure level of 0.036 mg/m 3

and the
NOAEC for local irritation effects of 178 mg/m 3
is judged to be sufficient taking into account th e nature of the observed effects (degenerative lesions of the olfactory mucosa) and the fact that no steep dose-response relationship is observed for the these effects. Considering the short-term exposure, see section Acute toxicity.

Conclusion ii)
There is at present no need for further info rmation and/or testing or for risk reduction measures beyond those which are being applied already.

MOS for
Dermal exposure scenario
The calculation of the dermal exposure due to hair setting lotions leads to an external exposure of 1 μg/kg bw/d. The margin of safety between the
external dermal exposure 1 μg/kg bw/d

and the
oral NOAEL of 684 mg/kg bw/d
is judged to be sufficient.

Conclusion ii)
There is at present no need for further info rmation and/or testing or for risk reduction measures beyond those which are being applied already.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 176 Mutagenicity
Vinyl acetate is not mutagenic to bacteria, but it induces chromosomal aberrations, gene mutations and SCE in several tests with mamma lian cells from different sources in culture.Furthermore, at high concentrations the formation of DNA-protein-crosslinks and DNADNA-crosslinks is shown with mammalian cells. The in vivo genotoxicity of vinyl acetate appears to be limited to toxic doses. Therefore, the substance may express its genotoxic potential onl y when defence mechanisms are overloaded and thus it may be reasonable to assume a th reshold mechanism of action for vinyl acetate genotoxicity. Taking into account the low consumer exposure (in the range of up to 20 μg/kg bw/d) based on the present knowledge it may be concluded that there is presently no concern regarding in vivo mutagenicity.

Conclusion ii)
There is at present no need for further info rmation and/or testing or for risk reduction measures beyond those which are being applied already.

Carcinogenicity
In cancer studies, vinyl acetate inhalation induced an increased number of nasal tumors (mainly papillomas and squamous cell carcinomas) in various regions of the nasal mucosa of rats. The total incidence was significantly in creased at a concentration of 600 ppm (2142 mg/m 3 ) but a single papilloma already devel oped at 200 ppm. Thus, the NOAEC of 50 ppm (178 mg/m 3 ) will be used for the risk characteris ation. No significant tumor response was seen in a mice cancer bioassay. Occasionally si ngle squamous cell tumors occurred at other sites of the respiratory tract in rats and mice.

For the oral route a marked increase of tu mor rates has been observed at 1000 ppm (rat (offspring); 70 mg/kg bw/d), at 5000 ppm (mous e; 750 mg/kg/d) and at 10000 ppm (male rat 442 mg/kg bw/d, female rat 575 mg/kg bw/d). Du e to limitations in the study design in the studies of Maltoni et al. (1997) and Minardi et al. (2002), the study of Umeda et al. (2004a) is considered of higher predictivity (cf. 4.1.2. 8). For lower doses, there is concern that occasional findings of tumors of the same type s that have been observed at high doses and which might also be related to vinyl acetat e exposure. Thus, the lowest concentration suspected to be carcinogenic was 400 ppm for the oral route (LOAEL, male rat 21 mg/kg bw/d, female rat 31 mg/kg bw/d, Umeda et al ., 2004a). Clearly tumor free dosages were not established in carcinogenicity studies for the or al route. Thus, 400 ppm (21 mg/kg bw/d male rat) is proposed as LOAEL for oral risk char acterisation. Since carcinogenicity is a critical toxicological endpoint a risk characterisa tion for the oral route was calculated.
Vinyl acetate exposure produced tumors at the s ite of first contact along the exposure routes by inhalative and oral uptake. A thresholded mode of carcinogenic action is thought to be active. Uncertainties exist in the proposed mode of action and should taken into account.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 177 MOS for
Inhalation exposure scenario
Long-term exposure to 0.036 mg/m3 vinyl acetat e is assumed to result via emission from carpets. The margin of safety for non-neoplastic effects between the
measured exposure level of 0.036 mg/m 3

and the
NOAEC 178 mg/m 3
is judged to be sufficient.

Conclusion ii)
There is at present no need for further info rmation and/or testing or for risk reduction measures beyond those which are being applied already.

MOS for
Oral exposure scenario
The oral route is not relevant for risk characterization (see introductory remarks).

Reproductive toxicity
Since no hazards have been identified regardi ng fertility and developmental toxicity a risk characterisation should not be performed. This decision is further supported by the fact that the systemic availability of vinyl acetate is very low.

4.1.3.4 Man exposed indirectly via the environment
Indirect exposure to humans via the environment occurs mainly by air. Following the local scenario data (at a point source) a maximum in take of a total daily dose of 0.036 mg/kg bw/d is calculated. For the regional scenario, the respective figure is 0.00247 μ g/kg bw/d.
The main route of indirect expos ure of both scenarios (local and regional) is the intake via inhalation of air (cf. 4.1.1.4). Theref ore the local concentration of 0.288 mg/m 3 for site 26 was selected (Table 3-11; highest value, in chapter 3.1.3.11) and used for risk characterisation.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 178 Repeated dose toxicity

Inhalation
Local effects on the respiratory tr act are not to be expected because of the low concentrations in the air of 0.288 mg/m 3 (local exposure). The NOAEC for local toxic effects on the respiratory tract of 50 ppm (178. 5 mg/m3) was derived from the 2-year studies on rats and mice.
MOS for
Inhalation exposure scenario
The margin of safety for non-neoplastic effects between the
estimated exposure level of 0.288 mg/m 3

and the
NOAEC 178 mg/m 3
is judged to be sufficient.

Conclusion ii)
There is at present no need for further info rmation and/or testing or for risk reduction measures beyond those which are being applied already.

Mutagenicity
Vinyl acetate is not mutagenic to bacteria, but it induces chromosomal aberrations, gene mutations and SCE in several tests with mamma lian cells from different sources in culture.Furthermore, at high concentrations the formation of DNA-protein-crosslinks and DNADNA-crosslinks is shown with mammalian cells . The in vivo genotoxicity of vinyl acetate appears to be limited to toxic doses thus it may be reasonable to assume a threshold mechanism of action for germ cell mutagenicity.
Taking into account the exposure estimates resulting for a point source from a worst case calculation and from regional background concentr ations it may be concluded that there is presently no concern regarding in vivo mutagenicity.
Conclusion ii)
There is at present no need for further info rmation and/or testing or for risk reduction measures beyond those which are being applied already.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 179 Carcinogenicity
Vinyl acetate inhalation induced an increased num ber of nasal tumors (mainly papillomas and squamous cell carcinomas) in various regions of the nasal mucosa of rats (cf. 4.1.2.8, 4.1.3.3). The total incidence was significantly increas ed at a concentration of 600 ppm (2142 mg/m 3 ) but a single papilloma already developed at 200 ppm. Thus, the NOAEC of 50 ppm (178 mg/m 3 ) will be used for risk characterisation purposes.
MOS for
Inhalation exposure scenario
The margin of safety for neoplastic effects between the
estimated exposure level of 0.288 mg/m 3

and the
NOAEC 178 mg/m 3
is judged to be sufficient.

Conclusion ii)
There is at present no need for further info rmation and/or testing or for risk reduction measures beyond those which are being applied already.

Reproductive toxicity
Since no hazards have been identified regardi ng fertility and developmental toxicity a risk characterisation should not be performed. This decision is further supported by the fact that the systemic availability of vinyl acetate is very low.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 180 4.2 HUMAN HEALTH (PHYSICO-CHEMICAL PROPERTIES)

4.2.1 Exposure assessment

4.2.1.1 Occupational exposure
Refer to chapter 4.1.1.1

4.2.1.2 Consumer exposure

4.2.1.3 Indirect exposure via the environment

4.2.2 Effects assessment: Hazard identifica tion and Dose (concentration) - response (effect) assessment

4.2.2.1 Explosivity
Vinyl acetate is not explosive.

4.2.2.2 Flammability
Vinyl acetate is highly flammable.

4.2.2.3 Oxidizing potential
Due to its chemical structure, vinyl acetat e is not expected to possess any oxidizing properties.

4.2.3 Risk characterisation

4.2.3.1 Workers
Vinyl acetate is highly flammable. Adequate wo rker protection measures must be observed. Risk reduction measures beyond those which are being applied already are not considered necessary.

Conclusion: iiR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 181 4.2.3.2 Consumers

4.2.3.3 Man exposed indirectly via the environmentR059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 182 5 CONCLUSIONS / RESULTS

Overall results of the risk assessment:

( ) i) There is need for further information and/or testing
(x) ii) There is at present no need for furt her information and/or testing and for risk reduction measures beyond those which are being applied already
(x) iii) There is a need for limiting the risks; risk reduction measures which are already being applied shall be taken into account

Summary of conclusions:

Environment
As a follow up to conclusion (i), which was drawn in the first draft of the Environment Section of the Comprehensive Risk Assessment Report of Vinyl acetate (August 2002), further acute and long-term toxicity tests were performed for the aquatic compartment and more data on a number of production and processing sites were obt ained, leading to the following revised risk characterisation.

conclusion iii):

Terrestrial compartment
A risk to the local terrestrial compartment can be identified for the life cycle stage of vinyl acetate processing. This conclusion applies to the generic processing scenario for the local main source. The unknown processing sites acc ount for a missing tonnage of 325,000 t/a (or 41 % of the total production volume of 800,000 t/a ), compared to a verified processing tonnage of 475,000 t/a. The risk characterisations for selected (worst case) production and processing sites with site specific data indicate no actual risk to the te rrestrial compartment. However, the highest PEC/PNEC ratio calculated with site specific data (0.86) is not very far from the PEC/PNEC ratio calculated for the generic processing scenario (2.33), and there was al so a risk at one of the production sites (which has been eliminated during the time of the preparation of this RAR). Consequently, it is not completely im plausible that unknown processing sites pose a risk to the terrestrial environment.
The risk characterisation for the terrestrial compartment could still be revised by requesting further testing (i.e. OECD 207 Earthworm acute t oxicity test and OECD 208 Terrestrial plants growth test). However, a further data improvement by means of testing is not considered a reasonable next step by the rapporteur for the following reasons.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 183 Further information on the toxicity of vinyl acet ate to terrestrial organisms allows for a reevaluation of the potential risk that emanates from the unknown processing sites, but delays risk reduction measures in case that a risk still remains with the new data. The rapporteur therefore proposes to enter directly into th e risk reduction phase, which would be more effective than further data improvement at this stage of the risk assessment.
Risk reduction measures should be considered for all facilities with a vinyl acetate processing capacity exceeding 20,000 t/a. This threshold is de rived from the generic processing scenario, assuming that vinyl acetate is released to so ils via sludge application and aerial deposition. Sites already applying advanced techniques would not require further consideration of risk reduction measures. It is known from some pr ocessing/production sites that techniques such as waste water distillation, sludge incinera tion or deposition in a landfill, waste gas incineration or vapour recovery systems can a void significant releases of vinyl acetate to soils. In principle, the rapporteur agrees with the proposal of SCHER that considering the volatility of the substance, terrestrial plants might be exposed via air. However, no guidance is available how to derive a PNEC for the air compartment. In addition, the available guidelines for terrestrial plants (OECD 208 / 227) are designed to include exposure through soil or by wet residues (e.g. spray drift of plant producti on products). To determine effects of volatile compounds, testing needs to be conducted in closed greenhouses or chambers under continuous exposure conditions. We feel this ki nd of testing is not appropriate for vinyl acetate, because no indications fo r high toxicity for plants exist. For other soil organisms, a continuous exposure to volatile compounds like vinyl acetate is negligible since the substance is expected to evaporate from the soil.

conclusion ii):

Aquatic compartment
A risk to the local or regional aquatic comp artment (surface water and sediments) was not identified for production and processing of vinyl acetate. This conclusion applies to all sites.

Atmospheric compartment
Based on a qualitative risk characterisation, no unacceptable risk for the atmosphere is expected from vinyl acetate. The substance is rapidly removed from air by chemical breakdown, adsorption to airborne particles or aerosols, and wet deposition. Furthermore, air concentrations indicate a negligible risk with regard to ecotoxicity.

Non-compartment specific effects
Non compartment specific effects (secondary pois oning) of vinyl acetate are not expected as there is no indication that the substance has potentially bioaccumulative properties.

Marine Assessment including PBT assessment

VAM does not meet the PBT/vPvB criteria. A risk for the regional or local marine environment is not expected.R059_0805_env_hh Draft of 29.05.2008

CAS No.: 108-05-4 184 Human Health

Workers
conclusion iii)
Conclusion iii is expressed for the endpoint of carcinogenicity after dermal contact. Skin contact of vinyl acetate should be reduced at s cenario 2a (manufacturing of formulations and products, vinyl acetate monomer), even if ev aporation of the substance reduces the contribution of dermal exposure.
On the background of cancer risks and repeated dose toxicity, air concentrations of vinyl acetate at the workplace should be controlled to a level in the range of 17.6 mg/m 3 (critical exposure level). Conclusion iii is derived for repeated dose toxicity after inhalation for scenario 2 (manufacturing of formula tions and products). This scenario with an exposure value of 14.6 mg/m 3 is a borderline case. Since there is the uncertainty concerning the reduction of the intraspecies factor and th e mode of action for carcinogenesis for this borderline scenario conclusion iii is drawn.

Consumers conclusion ii)
There is at present no need for further info rmation and/or testing and for risk reduction measures beyond those which are being applied already

Man exposed indirectly via the environment
conclusion ii)
There is at present no need for further info rmation and/or testing and for risk reduction measures beyond those which are being applied alreadyR059_0805_env_hh Draft of 29.05.2008

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CAS No.: 108-05-4 203 Zeiger, E., Anderson, B., Haworth, S., La wlor, T., Mortelmans, K. (1992): Salmonella mutagenicity tests: V. Results from the te sting of 311 chemicals. Environ Molec Mutag 19 (Suppl. 2), 2-141
Zenz, C. Cordaso, E.M. (1994): Vinyl acetate, Other important and widely encountered chemicals; Occupational medicine; 3rd ed.; C. Zenz, O.B. Dickerson, E.P. Horvath, Jr., Editors; Mosby-Year Book, St. Louis, page 710in
Zhang, X., Zhang, Q-Y., Liu, D., Su, T., Weng, Y., Ling, G., Chen, Y., Gu, J., Schilling, B. Ding, X. (2005) Expression of cytochrome P450 and other biotransformation genes in fetal and adult human nasal mucosa. Drug Metabolism and Disposition 33: 1423-1428
Zissu, D. (1995) Histopathological changes in th e respiratory tract of mice exposed to ten families of airborne chemicals. J Appl Toxicol 15:207

## Appendix I

of the Risk Assessment Report

Vinyl acetate

CAS-No.: 108-05-4

Estimation of Abiotic Degradation

April 2005

CAS-No.: 108-05-4 1AOP V1.91 ESTIMATION OF ABIOTIC DEGRADATION
EstimateSMILES : C=COC(=O)C CHEM : C:\EPISUITE\VAM.mol MOL FOR: C4 H6 O2 MOL WT : 86.09

SUMMARY (AOP v1.91): HYDROXYL RADICALS Hydrogen Abstraction = 0.0422 E-12 cm3/molecule-sec Reaction with N, S and -OH = 0.0000 E-12 cm3/molecule-sec Addition to Triple Bonds = 0.0000 E-12 cm3/molecule-sec Addition to Olefinic Bonds = 26.3000 E-12 cm3/molecule-sec Addition to Aromatic Rings = 0.0000 E-12 cm3/molecule-sec Addition to Fused Rings = 0.0000 E-12 cm3/molecule-sec

OVERALL OH Rate Constant = 26.3422 E-12 cm3/molecule-sec HALF-LIFE = 1.218 Days (12-hr day; 0.5E6 OH/cm3) HALF-LIFE = 14.617 Hrs ** Designates Estimation(s) Using ASSUMED Value(s)

SUMMARY (AOP v1.91): OZONE REACTION OVERALL OZONE Rate Constant = 0.175000 E-17 cm3/molecule-sec HALF-LIFE = 6.549 Days (at 7E11 mol/cm3)
Experimental Database Structure Match: Chem Name : Vinyl acetate CAS Number: 000108-05-4 Exper OH rate constant : 25 E-12 cm3/molecule-sec Exper OH Reference: (Saunders,S.M. et al.,1993) Exper Ozone rate constant: 3.2 E-18 cm3/molecule-sec Exper NO3 rate constant : --- cm3/molecule-sec
Hydrogen Abstraction Calculation: Kprim = 0.136 F(-C(=O)OR)=0.136(0.310)= 0.042 H Abstraction TOTAL = 0.042 E-12 cm3/molecule-sec

OH Addition to Olefinic Bonds Calculation: Kd = K(CH2=CH-)C(-O **)= 26.300(1.00) = 26.300 E-12 cm3/molecule-sec ASSUMED Values designated by: **

Ozone Reaction with Olefins Calculation: Ko = K(CH2=CH-R)O x(-Default Value **)= 0.175000(1.000) = 0.175000 E-17 cm3/molecule-sec ASSUMED Values designated by: **

CAS-No.: 108-05-4 2

## Appendix II

of the Risk Assessment Report

Vinyl acetate

CAS-No.: 108-05-4

Estimation of Biodegradability

April 2005

CAS-No.: 108-05-4 1BIOWIN V4.00 ESTIMATION OF BIODEGRADABILITY

SMILES : C=COC(=O)C CHEM : vinyl acetate
--------------------------- BIOWIN v4. 00 Results -------------- -------------- Linear Model Prediction: Biodegrades Fast
Non-Linear Model Prediction : Biodegrades Fast Ultimate Biodegradation Timeframe: Weeks Primary Biodegradation Timeframe: Days
MITI Linear Model Prediction: Readily Degradable
MITI Non-Linear Model Prediction: Readily Degradable

TYPE | NUM | BIOWIN FRAGMENT DESCRIPTION |COEFF | VALUE

------------------------------------------------------------------------------------- Frag | 1 | Ester [-C(=O)-O-C] |0. 1742 | 0.1742 MolWt | * | Molecular Weight Parameter | | -0.0410 Const | * | Equation Constant | | 0. 7475

RESULT | LINEAR BIO DEGRADATION PROBABILITY | | 0.8807

TYPE | NUM | BIOWIN FRAGMENT DESCRIPTION |COEFF | VALUE Frag | 1 | Ester [-C(=O)-O-C] |4. 0795 |4.0795 MolWt| * | Molecular Weight Parameter | | -1. 2225 RESULT | NON-LINEAR B IODEGRADATION PROBABILITY | | 0.9972

A Probability Greater Than or Equal to 0.5 indicates: Biodegrad es Fast A Probability Less Than 0.5 indi cates: Does NOT Biodegrade Fast TYPE | NUM | BIOWIN FRAGMENT DESCRIPTION | COEFF | VALUE Frag | 1 | Ester [-C(=O)-O-C] | 0. 1402 | 0.1402 MolWt| * | Molecular Weight Parameter | | -0. 1903 Const| * | Equation Constant | | 3. 1992 RESULT | SURVEY MODEL - ULTIMA TE BIODEGRADATION | | 3.1491

------------------------------------------------------------------------------------- TYPE | NUM | BIOWIN FRAGMENT DESCRIPTION | COEFF VALUE

------------------------------------------------------------------------------------- Frag | 1 | Ester [-C(=O)-O-C] | 0. 2290 | 0.2290 MolWt| * | Molecular Weight Parameter | | -0. 1242 Const| * | Equation Constant | | 3. 8477

CAS-No.: 108-05-4 2RESULT | SURVEY MODEL - PRIMAR Y BIODEGRADATION | | 3.9525
Result Classification: 5.00 -> hours 4.00 -> days 3.00 -> weeks (Primary & Ultimate) 2. 00 -> months 1.00 -> longer

TYPE | NUM | BIOWIN FRAGMENT DESCRIPTION | COEFF | VALUE

------------------------------------------------------------------------------------- Frag | 1 | Ester [-C(=O)-O-C] | 0. 3437 | 0.3437 Frag | 1 | Methyl [-CH3] | 0. 0004 | 0.0004 Frag | 3 | -C=CH [alkenyl hydrogen] | 0. 0062 | 0.0186 MolWt| * | Molecular Weight Parameter | | -0. 2561 Const| * | Equation Constant | | 0. 7121

RESULT | MITI LINEAR B IODEGRADATION PROBABILITY | | 0.8187

TYPE | NUM | BIOWIN FRAGMENT DESCRIPTION | COEFF | VAL UE

------------------------------------------------------------------------------------- Frag | 1 | Ester [-C(=O)-O-C] | 2. 4462 | 2.4462 Frag | 1 | Methyl [-CH3] | 0. 0194 | 0.0194 Frag | 3 | -C=CH [alkenyl hydrogen] | 0. 0285 | 0.0855 MolWt| * | Molecular Weight Parameter | | -2. 4853

RESULT | MITI NON-LINEAR BIODE GRADATION PROBABILITY | | 0. 9303

------------------------------------------------------------------------------------- A Probability Greater Than or Equal to 0.5 indicates --> Readil y Degradable A Probability Less Than 0.5 indi cates --> NOT Readily Degradable

CAS-No.: 108-05-4 3

## Appendix III

of the Risk Assessment Report

Vinyl acetate

CAS-No.: 108-05-4

Distribution and fate

April 2005

CAS-No.: 108-05-4 1Distribution and Fate

time d Tag
melting point:

vapour pressure:
water solubility:
part. coefficient octanol/water:

molecular weight:

gas constant:

temperature:
conc. of suspended matter in the river:
density of the solid phase:

volume fraction water in susp. matter:

volume fraction solids in susp.matter:

volume fraction of water in sediment:

volume fraction of solids in sediment:

volume fraction of air in soil:

volume fraction of water in soil:

volume fraction of solids in soil:

aerobic fraction of the sediment comp.:
product of CONjunge and SURF air : MP 180 K

.

VP 12000Pa

.
SOL 20000mg

. l 1

.

LOGP OW 0.7

MOLW 0.086 kg

. Mol 1

.

R 8.3143J

. Mol 1

. K 1

.

T 293 K

.

SUSP water 15 mg

. l 1

.

RHO solid 2500 kg

. m 3

.

Fwater susp 0.9

Fsolid susp 0.1

Fwater sed 0.8

Fsolid sed 0.2

Fair soil 0.2

Fwater soil 0.2

Fsolid soil 0.6

Faer sed 0.1

product 10 4 Pa

.

Distribution air / water: Henry-constant

HENRY VP MOLW

. SOL HENRY 51.6 Pa m 3

. Mol 1

. =

log HENRY

Pa m 3

. Mol 1

. 1.713 =

K air_water HENRY
R T

. K air_water 0.021 =

CAS-No.: 108-05-4 2Solid / water-partition coefficient Kpcomp and total compartment/water-partit ion coefficient Kcomp_water

a 0.52 (a,b from TGD, p. 541 for nonhydrophobics)

b 1.02 K OC 10 a LOGP OW . b l

. kg 1

. K OC 24.21 l kg 1

. = Suspended matter

Kp susp 0.1 K OC . Kp susp 2.421 l kg 1

. =

K susp_water Fwater susp Fsolid susp Kp susp . RHO solid . K susp_water 1.505 =

factor for the calculation of Clocal water :

faktor 1 Kp susp SUSP water . faktor 1 =

Sediment

Kp sed 0.05 K OC . Kp sed 1.211 l kg 1

. =

K sed_water Fwater sed Fsolid sed Kp sed . RHO solid . K sed_water 1.405 =

Soil

Kp soil 0.02 K OC . Kp soil 0.484 l kg 1

. =

K soil_water Fair soil K air_water . Fwater soil Fsolid soil Kp soil . RHO solid .

K soil_water 0.931 = Sludge (activated sludge)

K p_sludge 0.37 K OC . K p_sludge 8.958 l kg 1

. =

Raw sewage

K p_sewage 0.30 K OC . K p_sewage 7.263 l kg 1

. =

Elimination in STPs

rate constant in STP: k = 1 h -1 elimination P = f ( k, logpow, logH) = 90 %

fraction directed to surface water Fstp water = 0,1

CAS-No.: 108-05-4 3Biodegradation in different compartments

surface water

kbio water 0.047 d 1

. (TGD, table 5)

soil

DT50bio soil 30 d

. (TGD, table 6)

kbio soil ln 2 ( ) DT50bio soil kbio soil 0.023 d 1

=

sediment

kbio sed ln 2 ( ) DT50bio soil Faer sed . kbio sed 2.31 10 3

. d 1

=

Degradation in surface waters

khydr water 0.0407d 1

.

kphoto water 1 10 10

. d 1

.
kdeg water khydr water kphoto water kbio water

kdeg water 0.088 d 1

=

Atmosphere

calculation of CONjunge * SURFaer for the OPS-model

VPL VP
exp 6.79 1 MP 285 K

. . VP wenn MP 285 K

. > VPL , VP , ( ) VP 1.2 10 4

. Pa =

Fass aer product VP product degradation in the atmosphere Fass aer 8.333 10 9

. = kdeg air = 0,0475 h -1 (see AOP-calculation)

CAS-No.: 108-05-4 4

## Appendix IV

of the Risk Assessment Report

Vinyl acetate

CAS-No.: 108-05-4

Continental and regional exposure

May 2006

CAS-No.: 108-05-4 1SimpleBox2.0a INPUT - Vinyl acetate

Unit Input Physicochemical properties COMPOUND NAME [-] Vinyl acetate Substance MOL WEIGHT [g.mol -1 ] 86 Molecular weight MELTING POINT [° C] -93.2 Melting Point VAPOR PRESSURE(25) [Pa] 12000 Vapour pressure at 25°C log Kow [log10] 0.7 Octanol-water partition coefficient SOLUBILITY(25) [mg.l -1 ] 20000 Water solubility

Distribution - Partition coefficients - Solids water partitioning (derived from K oc ) Kp(soil) [l.kg d -1 ] 0.484 Solids-water partitioning in soil Kp(sed) [l.kg d -1 ] 1.211 Solids-water partitioning in sediment Kp(susp) [l.kg d -1 ] 2.421 Solids-water partitioning in sudpended matter - Biota-water BCF(fish) [l.kg w -1 ] 3.16 Biocentration factor for aquatic biota

Degradation and Transfromation rates - Characterisation and STP PASSreadytest [y / n] y Characterization of biodegradability - Environmental Total Degradation kdeg(air) [d -1 ] 1.14E+00 Rate constant for degradation in air kdeg(water) [d -1 ] 8.80E-02 Rate constant for degradation in bulk surface water kdeg(soil) [d -1 ] 2.30E-02 Rate constant for degradation in bulk soil kdeg(sed) [d -1 ] 2.31E-03 Rate constant for degradation in bulk sediment

Sewage treatment (e.g. calculated by SimpleTreat) - Continental FR(volatstp) [C] [-] 1.16E-01 Fraction of emission directed to air (STPcont) FR(effstp) [C] [-] 1.00E-01 Fraction of emission directed to water (STPcont) FR(sludgestp) [C] [-] 2.00E-03 Fraction of emission directed to sludge (STPcont) - Regional FR(volatstp) [R] [-] 1.16E-01 Fraction of emission directed to air (STPreg) FR(effstp) [R] [-] 1.00E-01 Fraction of emission directed to water (STPreg) FR(sludgestp) [R] [-] 2.00E-03 Fraction of emission directed to sludge (STPreg)

Release estimation - Continental
Edirect(air) [C] [t.y -1 ] 2879,52 Total continental emission to air
STPload [C] [t.y -1 ] 364.78 Total continental emission to wastewater Edirect(water1) [C] [t.y -1 ] 0 Total continental emission to surface water Edirect(soil3) [C] [t.y -1 ] 0 Total continental emission to industrial soil Edirect(soil2) [C] [t.y -1 ] 0 Total continental emission to agricultural soil
Edirect(air) [R] [t.y -1 ] 319,95 Total regional emission to air
STPload [R] [t.y -1 ] 40.53 Total regional emission to wastewater Edirect(water1) [R] [t.y -1 ] 0 Total regional emission to surface water Edirect(soil3) [R] [t.y -1 ] 0 Total regional emission to industrial soil CAS-No.: 108-05-4 2Edirect(soil2) [R] [t.y -1 ] 0 Total regional emission to agricultural soil

SimpleBox2.0a OUTPUT - Vinyl acetate

Physicochemical properties COMPOUND NAME [-] Vinyl acetate Substance

Output - Continental PECsurfacewater (total) [mg.l -1 ] 9,22E-07 Continental PEC in surface water (total) PECsurfacewater (dissolved) [mg.l -1 ] 9,22E-07 Continental PEC in surface water (dissolved)
PECair [mg.m -3 ] 1,87E-06 Continental PEC in air (total) PECagr.soil [mg.kg wwt -1 ] 1,10E-07 Continental PEC in agricultural soil (total) PECporewater agr.soil [mg.l -1 ] 2,02E-07 Continental PEC in pore water of agricultural soils
PECnat.soil [mg.kg wwt -1 ] 4,64E-08 Continental PEC in natural soil (total)
PECind.soil [mg.kg wwt -1 ] 4,64E-08 Continental PEC in industrial soil (total)
PECsediment [mg.kg wwt -1 ] 9,51E-07 Continental PEC in sediment (total) - Regional PECsurfacewater (total) [mg.l -1 ] 8,33E-06 Regional PEC in surface water (total) PECsurfacewater (dissolved) [mg.l -1 ] 8,33E-06 Regional PEC in surface water (dissolved)
PECair [mg.m -3 ] 9,67E-06 Regional PEC in air (total) PECagr.soil [mg.kg wwt -1 ] 9,05E-07 Regional PEC in agricultural soil (total) PECporewater agr.soil [mg.l -1 ] 1,66E-06 Regional PEC in pore water of agricultural soils
PECnat.soil [mg.kg wwt -1 ] 2,40E-07 Regional PEC in natural soil (total)
PECind.soil [mg.kg wwt -1 ] 2,40E-07 Regional PEC in industrial soil (total)
PECsediment [mg.kg wwt -1 ] 8,62E-06 Regional PEC in sediment (total)

CAS-No.: 108-05-4 3Vinyl Acetate_MTD_0209.doc11.09.2002Appendix:MTD exceeded in vinyl acetate studies?The question has been raised whether the highest concentrations/doses tested exceed the maximum tolerated dose (MTD).The MTD has been exceeded if a test concentration induce the following effects:Significantly reduced body weight (BW) gain (reduction of≥10%) as sign of nonspecific toxicity oras consequence of systemic/specific toxiceffects•Treatment-related mortalities, associated with significantly reduced life spans in long-term studies•Indications on severe systemic toxicity from clinical, functional, laboratory or morphological examinationsThe following repeated dose studies with inhalation and oral exposure to vinyl acetate have been analysed:(Sequences of studies analogue to RAR Chapters on Repeated dosetoxicity/Inhalation studies and Carcinogenicity/Inhalation studies)ReferenceTreatmentrelatedMortalitiesMean BW/gainreduction% Decrease infinal BW orBW gainFood andwaterconsumptionestimated/reducedRespiratorytract toxicityClinical signsof toxicityOrgan toxicityother thanResp TractIndicated thatdoses exceedMTD?Inhalation routeGage, 19703 w study onrats0, 100, 250,630, 2000 ppm(shortlysummerizeddata only)No incidentaldeaths in ratsLow BW gain inM/f 2000 ppm &F≥250 ppmNo quantitativedataNo data2000 ppmalveolarhistiocytosis2000 ppm:eye/noseirritation,respiratorydifficultiesNo indicationfrom necropsy(organsexaminedhistopathologically unknown)No (noindication onsystemic toxiceffects, degree& relevance oflow BW gainunknown, nodata on foodconsumption)Owen, 1979a,b4 wk rangefinding studiesonmice & rats0, 150, 500,No incidentaldeaths in ratsand miceSignificantlower BW gainin m/f mice at1000 ppmNon-significantNo tables orfiguresavailableNo dataNo dataMice≥150 ppm& rats≥500ppm intermittentrespir distress ,hunchedNo indicationfrom necropsy,lower spleenweights in malemice at 1500No (noindication onsystemictoxicity,relevance ofVinyl Acetate_MTD_0209.doc11.09.20021000, (50/)1500ppmdecrease in BWgain in rats upto 1500 ppmpostureppm and malerats at≥1000ppm(nohistopathology)lower BW gainquestionablesince no dataon foodconsumption,Low BW gain atconcentrationabove thoseinducingrespiratorydistress)Bogdanffy et al.,1997 1,5 or 20 d(cellproliferation)studies onrats0, 50, 200, 600,1000 ppmNo incidentaldeathsReduced meanBW at 1000ppm day 3 today 26-11% at the endof study, max –14% in week 5No dataOlfactorydegeneration≥600 ppm,minimaldegenration inrespiratorymucosa at 1000ppmNo effectobserved/reportedNo dataNo (absence ofmortalities, noindication ofsystemictoxicity,reduced BWgain at doseabove thoseinducing nasaltoxicity, no dataon foodconsumption)Owen, 1980 a,b90 day studiesonrats & mice0, 50, 200, 1000ppmRat: Oneincidentaldeath in acontrol rat,Mice: in 6 f and3 m of highdose, 2 mcontrols, alldied duringblood samplingprocedureRats & mice:Lower meanfinal BW andsignificantlyeduced BWgain at 1000ppmRats:Meanfinal BW in mand f -19%Mean BWgain– 38% (m), -54% (f) lower in1000 ppm ratsMice: Meanfinal BW in m –18% and in f17%,Mean BWgainNo dataRats:Lungeffects (relatedto parasiticinfection),Miceat 1000ppm metahyperplasia,inflammation innasal mucosa(type ofepithelium notidentified),Mice≥200 ppmand rats 1000ppm intermittentrespiratorydistress,hunchedposture, ruffledfurNo dataNo (notreatmentrelatedmortalities, noindication onsystemictoxicity, lowerBW gain atconcentrationabove or equalto thoseinducingVinyl Acetate_MTD_0209.doc11.09.2002– 60% (m) –50% (f) in 1000ppm micetrachea,bronchiarespiratorysymptoms, nodata on foodconsumption)Owen, 1988,Bodanffy et al.,1994b 53 wk, 83wk, 2 years, or70 wk plus 16wk recovery onrats and mice 0,50, 200, 600ppmNo treatmentrelatedmortalitiesRats & mice:End of study:significantlylower BW gainat 600 ppm andin mice at 200ppm:Rats & Mice:mean final BWat the end ofstudy rats: (m)–10% (f) –15%( no dataspecified), miceat 600 ppm(m&f) –15%),not quantifiedfor 200 ppmRats:Decreasedblood glucose (fat 600 ppm) andreduced urinevolume (m & f at600 ppm) arecontributed tothenonmeasuredreduced foodand waterconsumptionRats & Mice:≥200 ppmolfactorydegeneration,metaplasiaTrachea (inmice at 600ppm) metahyperplasiarough haircoat,hunchedposture, lung(600 ppm rats &mice) increasedweight,degeneration ofbronchiolarepithelium,alveolarhistiocytosisRats & Mice:≥50 ppm roughhaircoat,hunchedpostureNo toxic effectin other organsystemNo (Theauthorsinterpretedlower glucoselevels andoligurie asindicative forreducedconsumption ofwater/food, notreatmenrelatedmortalities, noindication onsystemictoxicity, no dataon food andwaterconsumption)Vinyl Acetate_MTD_0209.doc11.09.2002Oral administrationReferenceTreatmentrelatedMortalitiesMean BW/gainreduction% Decrease infinal BW orBW gainFood and waterconsumptionestimated/reducedGastrointestinal tracttoxicityClinicalsigns oftoxicityOrgan toxicityother thangastrointestinal tractIndicated thatdoses exceedMTDGale, 1979 4-wkdose rangefinding studiesonrats & mice0, 50 (to 10000ppm in wk 4),150, 1000 or5000 ppm inwaterNo mortalitiesReduced BWgain in ratsf≥1000 ppmand m≥5000ppm and inmale mice at5000 ppmNo dataRats:Reducedwaterconsumptionf≥1000 ppm andm≥5000 ppm,reduced foodconsumption f at10000 ppm (-11%)Mice:Reducedwaterconsumption in mat≥1000 ppm andf≥5000 ppm,reduced foodconsumption in fat 5000 ppm-Mice: tremorandhypothermiainonef at5000 ppmMiceat 5000ppm: Reducedthymus weightRats & miceatall doses: lowerliver weightwithoutcorrespondingalterations(significance?)No (nomortalities, nosystemic toxiceffect, tremorandhypothermia ina female micemight indicatenonspecifictoxicity,reduced BWonly at dosesequal or abovethose withreduced water& foodconsumption)Gale, 1980 13-wk studies(OECD 408) inrats & mice, o,200, 1000, 5000ppmNo treatmentrelatedmortalitiesNonsignificantlylower mean BWin m rats at5000 ppm (-8%)Mice: no effecton overall BWgain-Rats:significantlyreduced waterconsumption in m& f at 5000 ppm (-23%, -25%) ,transientlyreduced in m&f at1000 ppmMice: no changeof water and foodconsumption-NoeffectobservedNo effectobservedNo (nomortalities, nosystemic/specific or nonspecifictoxic effects inrats up to 5000ppm, slightlylower BWassociated toreduced waterconsumption)Vinyl Acetate_MTD_0209.doc11.09.2002DuPont, 200092-day study oncell proliferationof oral cavity inrats0, 1000,5000, 10000,24000 ppm,males onlyNo mortalitieslower mean BW≥5000 ppm &lower BW gain≥5000lower mean BW-8.8, -7.4, -6.1%lower BW gainppm -13.4, -11,-9.2%significantly lowerwaterconsumption≥5000 ppm, (-28, -37, -40.3%) loweroverall foodconsumptionnonsign. At 5000ppm (-7.2%),signif. At≥10000ppm (-6%, - 7.4%), no effect on foodefficiencyOral cavity:Increasedproliferationrates≥10000ppm thoughout& at the end ofthe studyNo clinicalsign of toxicityor grosslesionsNo dataNo (nomortalities, nosystemic/specific or nonspecificeffects in ratsup to 24000ppm, lower BWassociated tolowerwater/foodconsumption)DuPont 200092-day study oncell proliferationin the oral cavityinmice0, 1000,5000, 10000,24000 ppm,males onlyNo mortalitiesno effect onBW/BW gain-significantlylowerwaterconsumption at≥1000 ppm (-23, -30.5, -31.4, -35%),no effect onoverall foodconsumption &efficiencyOral cav ity:Increased cellproliferation atday 92 onlyNo clinicalsign of toxicityor grosslesionsNo dataNo (nomortalities, nosystemic/specific or nonspecificeffects in miceup to 24000ppm, no effecton BW)Bogdanffy et al.,1994a 2 years,interimsacrifices at wk52, 78rats0,200, 1000, 5000ppmNo treatmentrelatedmortalitiesReduced BWgain at 5000ppm m –11% in1styear, -17%2ndyear, f -11%2ndyearSignificantlylowerwaterconsumption at1000 ppm (m -4.5% to max. –11%, f –5%-max.16% at variousintervals), at 5000ppm (m –18% tomax. – 34%, f –20% to max. 39%)reduced foodconsumption in mNo tissues fromoral cavityexamined forhistopathology,no effect ontongue andstomachNo clinicalsign of toxicityor treatmentrelated grosslesionsNo toxic effectNo ( nomortalities, nosystemic/specific or nonspecifictoxic effects inrats up to 5000ppm, effect onBW in males at5000 related toreduced waterconsumption≥1000 ppm & tolower foodVinyl Acetate_MTD_0209.doc11.09.2002at 5000 ppm (-3%to max. –12%)consumption at5000 ppm)Lijinsky andReuber, 1983130 wk,ratsat0, 1000 or 2500ppmNo treatmentrelatedmortalitiesNo data-No dataNo dataNo dataNo dataStudyinsufficientCelanese, 1998(=JapaneseBioassay) 104wkrats & mice0, 400, 2000,10000 ppmNo treatmentrelatedmortalitiesRats:lowermean in m& f at10000 ppm atthe end of studyMice:Lowermean BW in 2ndyear in m &f at10000 ppmRats: about 6-7% belowcontrols(calculatedfrom graphics)Mice: m 37 gversus 52 g incontrols, about–20%(f) to30% (m) at theend of studyRats:lower waterconsumption at10000 ppmthroughout thestud, about –27%to –30% at theend of study(calculated fromgraphics)Mice: Low waterconsumption in 2ndyear at 10000ppm, at the end ofstudy about –18%(f) to –35% (m)(calculated fromgraphics), Noeffect on foodconsumptionNo data ontoxic effectsNo data onclinical signsNo dataNo (noindication onsystemic/specific toxic effects,low BW in mice& rats related toreduction inwaterconsumption)Vinyl Acetate_MTD_0209.doc11.09.2002Conclusion:1. From inhalation studies on repeat-dose toxicity (subacute, subchronic, chronic) or carcinogenicity (2 years)•there were no treatment-related mortalities,•no indication on systemic toxicity•significantly reduced body weigth gain and final body weightReduced body weight gain is one of the critieria indicative for an excess of MTD. In inhalation studies on vinyl acetate , a (significant) reduction inmean final body weight or mean body weight gain was seen at concentrations of 1000 ppm in rats and mice exposed for 4 weeks until 90 days.When rats and mice were exposed to vinyl acetate during 2 years, lower BW gain was observed at 600 ppm, which is the dose inducing asignificant increase in nasal tumors in rats and the highest dosetested. Significantly reduced urine volume and glucose levelsduring and at theend of study indicated that lower body weight gain can be attributed to reduction in the water and food consumption that was not measured in thisand all other studies.Although not examined, it is likely, that reduced BW gain and lower bw gain was interpreted to be related to reductions in water and/or foodconsumption.Therefore, for concentrations up to 600 ppm exposed during 2 years the MTD was not exceeded.2. For the oral studies on repeat-dose toxicity (subacute and subchronic)•There were no treatment-related mortalities,•no indication on nonspecific or systemic/specific toxicity•and reduced mean BW (gain) was interpreted to be related to the lower water/food consumption.Presumably due to a bad palatibility in drinking water, rats and mice of the oral studies had a reduced water or water and foodconsuption.Because of the absence of other toxic effects and the consistency of dose-responses, the lower mean BW or BW gain was attributed to thereduced consumption of water and food.Therefore, for doses up to 24000 ppm administered up to 2 years, the MTD was not exceeded.