MINISTERIO DE SANIDAD Y CONSUMO 

DIRECCION GENERAL DE SALUD PUBLICA 

SUBDIRECCION GENERAL DE SANIDAD AMBIENTAL 

<< 

4 

061 

P. 1 

Subject : EU-Regulation 793/93, draft risk assessment report 

ACETONITRILE (CAS 75-05-8) . 

Dear colleague, 

Please find enclosed, the first draft of the risk 

assessment acetonitrile, (first priority list), prepared by the 

Spanish, C .A . The report will be discussed at the next Technical 

Meeting, on April 28-30 and at the SIAM 6 in Paris . 

Yours sincerely, 

Madrid, 4th March 1997 

Fdo . : Dr . Francisco Vargas Marcos . 

(For Spain Competent Authority) 

To al SIDS ontact Points ~~~ D 

To al As for Reg 93/793 p i'~ 

Mr . P . Mc . Cutcheon, CEC, DGXI ~ ~ t uU Mr . B .Hansen, CEC, DG XI, ECB 
MINISTERIO DE SANIDAD Y CONSUMO 

DIRECCION GENERAL DE SALUD PUBLICA 

SUBDIRECCION GENERAL DE SANIDAD AMBIENTAL 

RISK ASSESSMENT 

OF 

ACETONITRILE 

DRAFT REPORT 
CONTENTS Page 

0 OVERAL CONCLUSIONS OF THE RISK ASSESSMENT 1 

1 GENERAL SUBSTANCE INFORMATION 2 

1 .1 Identification of the substance 2 

1 .2 Purity/impurities, additives 2 

1 .3 Physico-chemical properties 2 

1 .3 .1 Physical state (at ntp) 3 

1 .3 .2 Freezing point 3 

1 .3 .3 Boiling point 3 

1 .3 .4 Relative density 3 

1 .3 .5 Vapour pressure 3 

1 .3 .6 Solubility 3 

1 .3 .7 Partition coefficient 3 

1 .3 .8 Flash point 3 

( 1 .3 .9 Autoflammability 3 

1 .3 .10 Flammability 4 

1 .3 .11 Explosive Properties 4 

1 .3 .12 Surface tension 4 

1 .3 .13 Dissociation constant 4 

1 .4 Classification 6 

2 GENERAL INFORMATION ON EXPOSURE 7 

2 .1 Production 7 

2 .2 Use 7 

3 ENVIRONMENT 

3 .1 Exposure assessment 

3 .1 .0 General discussion 

3 .1 .0 .1 Releases into the environment 

3 .1 :0 .1 .1 Releases from production 

3 .1 .0 .1 .2 Releases from use 

3 .1 .0 .1 .3 Releases from other sources 

3 .1 .0 .2 Degradation 

3 .1 .0 .2 .1 Abiotic degradation 

3 .1 .0 .2 .2 Biodegradation 

3 .1 .0 .3 Distribution 

3 .1 .0 .4 Accumulation 

3 .1 .1 Aquatic compartment (incl . sediment) 

3 .1 .1 .1 Calculation of Predicted Environmental 

Concentrations 

3 .1 .1 .2 Measured levels 

3 .1 .1 .3 Comparison of PECs with measured levels 

3 .1 .2 Terrestrial compartment 

3 .1 .2 .1 Calculation of Predicted Environmental 

Concentration 

3 .1 .2 .2 Measured levels 

3 .1 .3 Atmosphere 

3 .1 .3 .1 Calculation of Predicted Environmental 

Concentrations 

3 .1 .3 .2 Measured levels . 

3 .1 .3 .3 Comparison of PECs with measured levels 

9 

9 

9 

9 

9 

11 

13 

15 

15 

16 

18 

18 

18 

18 

22 

22 

23 

23 

23 

24 

24 

25 

25 
4 .1 .2 .8 Carcinogenicity 72 

4 .1 .2 .8 .1 Studies in animals 72 

4 .1 .2 .8 .2 Studies in humans 75 

4 .1 .2 .8 .3 Summary of carcinogenicity of 

acetonitrile 76 

4 .1 .2 .9 Toxicity for reproduction 76 

4 .1 .2 .9 .1 Studies in animals 76 

4 .1 .2 .9 .2 Studies in humans 81 

4 .1 .2 .9 .3 Summary of toxicity for 

reproduction 82 

4 .1 .3 Risk caracterisation 82 

4 .1 .3 .0 General aspects 82 

4 .1 .3 .1 Workers 86 

4 .1 .3 .1 .1 Manufacture 86 

4 .1 .3 .1 .2 End uses 87 

4 .1 .3 .2 Consumers 87 

4 .1 .3 .3 Man exposed indirectly via the environment 88 

4 .2 Human health (physico-chemical properties 88 

4 .2 .1 Exposure assessment 88 

4 .2 .1 .1 Workers 88 

4 .2 .1 .2 Consumers 89 

4 .2 .1 .3 Man exposed indirectly via the environment 89 

4 .2 .2 Effects assessment 89 

4 .2 .2 .1 Explosivity 89 

4 .2 .2 .2 Flammability 89 

4 .2 .2 .3 Oxidizing potential 89 

4 .2 .3 Risk characterizacion (physico-chemical properties) 89 

5 CONCLUSIONS 90 

6 REFERENCES 91 

Appendix A 
0. OVERALL CONCLUSIONS OF THE RISK ASSESSMENT 

CAS N°: 75-05-8 

EINECS N°: 200-835-2 

Substance Name (IUPAC Name): ACETONITRILE 

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

Sensitization 

No data is available on sensitization of acetonitrile . 

Therefore, there is need for testing for skin sensitization in accordance with the 

EU-Annex V-standard. 

Mutageniitv 

Acetonitrile did no induce gene mutations neither in bacteria nor in mammalian 

cells in culture . Showed week clastogenic activity in cultured mammalian cells . 

However, was found to be a inducer of aneuploid in a diploid strain of 

Saccharomyces cerevisae and in Drosophila melanogaster. In addition, positive 

results, in vivo, were reported in micronucleus test. 

Additional well-validated, in vivo, study in order to detect chromosome damage 

is required, before further conclusions can be made with regard to the risk 

assessment. 

Workers 

This conclusion is reached because the highest levels of exposure obtained in 

the "end uses" scenario have limited meaningfulness since the processes, work 

practices and the activities involved are not described and information on the 

duration and frequency of exposure are not available . 

(ii) There is at present no need for further information and/or testing or for risk 

reduction measures beyond those being applied already . 

This conclusion applies to: 

The environmental risk, with respect to aquatic compartment, including water, 

sediments and biological processes of WWTP. Terrestrial environment, at the 

regional and continental levels, as well as non compartment specific effects 

relevant to the food chain (secondary poisoning) . 

This conclusion also applies to risk to workers involved in the acetonitrile 

manufacture, consumers, risk from indirect exposure of man via the 

environment and from physic-chemical properties . 

-1- 
1 . GENERAL SUBSTANCE INFORMATION 

1 .1 . Identification of the substance 

IUPAC name : ACETONITRILE 

Synonyms: Cyanomethane, Ethanenitrile, Ethyl nitrile, 

Methanecarnitrile, Methyl cyanide 

EEC N4: 200-835-2 

EINECS N°: 200-835-2 

CAS N4: 75-05-8 

N4 INDEX (Annex I) : 608-001-00-3 

Molecular formula: C21-13N 

Molecular weight: 41 .05 

Structural formula: 

H 

H-C-C--- N 

H 

1 .2. Purity/impurities, additives 

Degree of purity: >_ 99.5 % 

Identity and percentage of impurities : 

- Propionitrile (0 .02 %) 

- Water, distilled, conductivity or of similar purity (0.01%) 

1 .3. Physico-chemical properties 

Acetonitrile is a volatile, colourless liquid with a sweet, etherlike odour. It is 

infinitely soluble in water and readily miscible with ethanol, ether, acetone, chloroform, 

carbon tetrachloride and ethylene chloride . It is immiscible with many satured 

hydrocarbons (petroleum fractions) . Acetonitrile has high dielectric constant and high 

polarity and strongly reactive (Hawley's Dictionary) . 

-2- 
Acetonitrile produces hydrogen cyanide when heated to decomposition or when 

reacted with acids or oxidizing agents (Reynolds, 1982). 

1 .3 .1 . Physical state at normal temperature and pressure (ntp) 

Acetonitrile is a volatile, colourless liquid with a sweet etherlike odour. 

1 .3.2. Melting point 

Grayson, (1985) gives a value of -45.7°C. Verschuerenk, (1983), the Merck 

Index. 11th Edition (1989) and Aldrich, catalogue handbook (1994-1995) give values 

between: -41 °C - -48°C. 

1 .3.3. Boiling point 

Merck Index, (11 th Edition) and Howard Ph (1993) give the figure 81 .6°C at 

1013.25 hPa. 

1 .3.4. Relative density 

IUCLID presents a density of 0.786 at 20oC (Aldrich, 1994-1995) . 

1 .3.5. Vapour pressure 

The ca. value provided in the IUCLID is between 94.51-98.64 hPa at 20°C 

(Verschueren K., 1983, Envirofate, 1994) . 

1 .3.6 . Water solubility 

Acetonitrile is infinitely soluble in water . (Clayton & Clayton, 1982) . Sax N.I . 

(1989) gives a value for water solubility 999999-999 mg/I at 25°C. 

1 .3 .7. Partition coefficient (log n-octanol/water) 

IUCLID provides a value of -0.34 (Leo A. et al ., 1971) . 

1 .3.8. Flash point 

Two values 5°C and 5 .6°C are given as flash point (open cup) (Aldrich, 1994-

1995, Reynolds, 1982) . In closed cup the value is 12 .8°C (Reynolds, 1982) . These 

values conclude in the R-phrase: R11 . 

1 .3 .9 . Autoflammability 

Sax. N.I ., 1989; provides a value of 524°C. 

-3- 
1 .3.10. Flammability 

Acetonitrile is highly flammable, with a lower flammability limit of 4.4% in volume 

and an upper flammability limit of 16% in volume. These data are obtained from 

Grayson M. (1985) and Sax N.I . (1989) . 

1 .3.11 . Explosive properties 

Sax. N.I ., (1989) ; presents that acetonitrile forms explosive mixtures with air. 

The lower explosive limit is 3.05% in volume and the upper explosive limit 17% in 

volume. 

1 .3.12. Surface tension 

29.04 dynes/cm at 20°C (Merck Index, 11th Edition, 1989) . 

1 .3.13. Dissociation constant 

pKa = 29 .1 (Howard, P.H ., 1993) . 
Table 1 .3 .- Physico-Chemical Properties of Acetonitrile 

PROPERTY VALUE REMARKS 

Physical state Liquid - Colourless with a sweet, 

(at ntp) etherlike odour. 

- Produces hydrogen cyanide 

when heated or when reacted 

with acids or oxidizing agents. 

Melting point -41 - -48 

'C 

Boiling point 81 .6 At 1013.25 hPa 

°C 

Relative density (d4Z°) 0.786 

Vapour pressure 94.51-98.64 At 20°C 

hPa 

Water solubility 999999.999 Infinitely soluble in water 

(at 25°C) 

mg/I 

Partition coefficient 0.34 

Log n-octanoVwater 

Flash point 5-5.6 (open cup) 

°C 12.8 (dosed cup) 

Autoflammability 524 

°C 

Flammability 4.4 Lower flammability limit (LFL) 

9b in volume 16 Upper flammability limit (UFL) 

Explosive properties 3.05 Lower explosive limit (LEL) 

% in volume 17 Upper explosive limit (UEL) 

Conversion factor 1 .68 At 25°C 

mg/m' 

Henry's Law Constant 2 .04x10'5-2 .93x10-5 At 25°C 

atm .m'/mol 

Relative vapour density 1 .42 

(air=1) 

Refractive index 1 .34604 At 15°C 

1 .33934 At 30°C 

Surface tension 29.04 At 20°C 

dynes cm 

Dissociation constant 29.1 

pKa 

-5- 
1 .4. Classification and labelling 

Classification according to Annex I of Directive 67/548/EEC 

Symbol and indication of danger: 

F: Highly flammable 

T: Toxic 

Risk phrases: 

R11 : Highly flammable 

R23/24/25 : Toxic by inhalation, in contact with skin and if swallowed 

Labelling: F, T, R11-23/24/25 

S16-27-45 

Specific concentrations limits : C>_2096 T; R23/24/25 

Specific concentrations limits : 3%<_C<20% Xn; R20/21/22 
2. GENERAL INFORMATION ON EXPOSURE 

2.1 . Production 

Acetonitrile is obtained as a by-product of acrylonitrile synthesis, by a method 

known as the SOHIO (Standard Oil Company of Ohio) process, which involves a high 

temperature catalytic reaction between propylene and ammonia and produces crude 

acrylonitrile containing acetonitrile, hydrogen cyanide and carbon oxides as the main 

impurities. The reported ratio of acetonitrile/acrylonitrile in this product varies between 

3% (Lowenheim and Moran, 1975; Kirk-Othmer 1978) and 109'a (Riegel, 1974; 

Reinders 1983) . Acetonitrile is obtained from the reaction product, after cooling, by 

fractional distillation . The main organic impurity in commercial acetonitrile is 

propionitrile together with small amounts of allyl alcohol (Kirk-Othmer, 1978; USEPA, 

1992). 

Other potential routes of acetonitrile synthesis are the dehydration of acetamide, 

the reaction of ammonia and acetylene, the ammonolysis of glacial acetic acid and the 

catalytic reaction of ethanol and ammonia (Merck, 1989; USEPA, 1980) . 

Acetonitrile is produced in EU by 2 companies in 2 european countries and one 

company imports this product from outside, Table 2.1 . 

2.2. Use 

Acetonitrile is used in different processes in the chemical industry and in 

research laboratories . The use pattern of this compound is shown in Table 2.2 . 

This compound is used as a starting material for the synthesis of many 

chemicals, pharmaceutical and pesticides and in the manufacturing of photographic 

film . 

Acetonitrile is used as a solvent in various extraction processes like butadiene 

extraction from C, streams and isoprene from C5 streams, dissolution of cationic textile 

dyes, recrystallization of steroids, extraction of fatty acids from animal and vegetable 

oils and removal of tars, phenols and colouring matter from petroleum hydrocarbons. 

Acetonitrile is widely used in research and analytical laboratories . It is used as 

a solvent for genetic engineering research and in the analytical determination of a 

great number of chemicals by high performance liquid chromatography (HPLC) .I n 

addition, it is used as an inert medium in physico-chemical investigations and as a 

solvent in non-aqueous titrations . 
Table 2.1 . Acetonitrile production and import in EU in 1993. 

Country Company Quantity (tonnes/year) 

produced or imported 

Germany' PCK AG Schwedt 1000-5000 

Italy Enichem S.p.A. 1000-5000 

United Kingdomb BP Chemicals Ltd. 1000-5000 

g1-990 data 

b imported from outside, 1992 data 

Table 2.2. Use pattern of acetonitrile 

Use Approximative percentage 

Pharmaceutical industry 50 

Extraction solvent 15 

Analytical laboratories (HPLC) 7 

Photographic film 7 

Pesticide manufacture 3 

Other uses 18 

Merck, 1989; USEPA, 1980; BP, 1992; Hawley, 1971 ; Borman, 1990 
3. Environment 

3.1 . Exposure assessment 

3.1 .q. General discussion 

Sources of acetonitrile release to the environment can be anthropogenic or 

natural. Acetonitrile occurs in coal tar in small amounts, has been detected in volcanic 

gases and quantified in emissions from the combustion of wood and other biomass. 

Acetonitrile is also released during its manufacture and use, from some 

industrial operations like shale oil retorting and coal gasification and from combustion 

processes in gas turbines, ignition engines and automobile exhaust. 

3.1 .0.1 . Releases into the environment 

3.1 .0.1 .1 . Releases from production 

Emission factors for acetonitrile during production have been reported by several 

authors. Bouscaren et al . (1986) quoted an emission factor of 2kg acetonitrile/tonne 

acrylonitrile, Reinders (1983) reported a range of factors, for acetonitrile release, 

between 1 and 7 kg acetonitrile/tonne acrylonitrile and USEPA (1980) reported a factor 

of 7.02 kg/tonne acrylonitrile produced . 

The emission factor to air, as well as to water and soil, has been estimated by 

using default values from the TGD and assuming that acetonitrile is in category Ic 

(intermediates stored off-site) . Table 3.1 shows the calculated emissions factors and 

releases of acetonitrile to air, water and soil compartments during production . The 

estimated emission factor to air (5 kg/ tonne acetonitrile) is lower than those previously 

reported (2-7.02 kg/tonne acrylonitrile) considering, as indicated in section 2.1, that the 

reported ratio of acetonitrile/acrylonitrile in crude acrylonitrile varies from 3 to 10%. 

Site specific information on releases of acetonitrile to air during production has 

been provided for one site and the total emission (fugitive and point emission) reported 

for two production plants was 77 tonnes/year in 1993, which corresponds to about 

256.6 kg/day per site and 128.3 kg/day per production plant. These values are higher 

than the calculated value using TGD default values, probably due to the fugitive 

(accidental) emissions, and 256.6 kg/day will be considered as a worst case release 

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3.1 .0.1 .2. Releases from use 

a) Use in the pharmaceutical industry 

Approximately 509'0 of acetonitrile produced is used by the pharmaceutical 

industry to manufacture different products like insulin, antibiotics and vitamins, Table 

2.2. In the manufacture of these products, the solvent is handled in close reaction and 

distillation sections, purified and recycled a number of times and the waste solvent is 

disposed of by licensed waste contractors. No site specific information is available 

regarding releases from this use . 

The emissions factors to the environment have been calculated by using default 

values from the TGD for industrial category 3 (chemical industry : chemicals used in 

synthesis) at processing, and main category Ic, Table 3.2 . 

Table 3.2. Release of acetonitrile from use In the pharmaceutical Industry 

Environment Compartment Emission 

factor 

Production 

Volume (t/a) 

Release 

(kg/day) 

Local Air 0.001 2,500 8.3 

Regional " " " 8.3 

Continental " " 7,500 25 

Local Water 0.007 2,500 58.3 

Regional " " " 58.3 

Continental " " 7,500 175 

Local Soil 0.0001 2,500 0.8 

Regional " " " 0.8 

Continental " " 7,500 2.5 

b) Use in butadiene production 

Approximately 15% acetonitrile is used as extraction solvent in the obtention 

of 1-3-butadiene from the mixed C4-hydrocarbon fraction in petrochemical cracking 

processes for ethylene manufacture . The emission factors reported by Reinders (1983) 

ranged from 0 - 0 .1 kg acetonitrile /tonne butadiene produced to air and the same 

range of emission factors to water. If it is assumed that acetonitrile is used exclusively 

in the butadiene extraction process and considering a butadiene production volume 

of 195,128 tonnes for the UK in 1990 (Chem-Fats 1991), the maximum release 

possible, using these emission factors, is about 65 kg acetonitrile / day for each 

compartment, air and water, for the production volumes of 1990 . 

-11- 

16 
The emission factors to the different environmental compartments have been 

calculated by using default values from the TGD for industrial category 3 and main 

category Ic, Table 3.3 . 

Table 3.3. Release of acetonitrile from use in butadiene production 

Environment Compartment Emission 

factor 

Production 

Volume (t/a) 

Release 

(kg/day) 

Local Air 0.001 750 2.5 

Regional " " " 2.5 

Continental " " 2,250 7.5 

Local Water 0.007 750 17.5 

Regional " 10 17.5 

Continental " " 2,250 52.5 

Local Soil 0.0001 750 0.25 

Regional " " " 0.25 

Continental " " 2,250 0.75 

Information on emissions data from a company have been provided during 1993 

and aqueous discharge was 4.70 tonnes/year, corresponding to 15.7 kg/day, which 

is in agreement with local water release shown in Table 3.3, although no information 

was given on the volume of acetonitrile used in butadiene production. Air point 

emissions of 2.93 tonnes acetonitrile/year (9.8 kg/day) were reported together with 

accidental discharges of 38.40 tonnes/year (128 kg/day). 

c) Other uses 

Acetonitrile is also used in the manufacture of photographic film, in the 

synthesis of some pesticides and in analytical and research laboratories, Table 2.2. 

In these processes, acetonitrile is used as a solvent in closed reaction or processing 

systems. When used in HPLC the solvent should be collected after use and disposed 

of by licensed waste contractors, although this may not always be accomplished. 
Table 3.4. Release of acetonitrile from other uses 

Environment Compartment Emission 

factor 

Production 

Volume (t/a) 

Release 

(kg/day) 

Local Air 0.001 1,750 5.8 

Regional 5.8 

Continental " " 5,250 17.5 

Local Water 0.007 1,750 40.8 

Regional 40.8 

; Continental " " 5,250 122.5 

Local soil 0.0001 1,750 0.6 

Regional " " " 0.6 

Continental " " 5,250 1 .8 

Information on the emissions for acetonitrile for these processes have not been 

found. Nevertheless, it is possible to estimate these emission factors assuming that 

359'0 of acetonitrile produced is used in these processes, Table 2.2, and using default 

values from the TGD for main category Ic, Table 3.4. 

3.1 .0.1 .3. Releases from other sources 

a) Biomass burning 

Biomass burning is widespread, particularly in the tropics and in developing 

countries, and serves various purposes such as clearing of forest, control of pests, 

nutrient mobilization, production of charcoal and energy production for cooking and 

heating (Crutzen and Andreae, 1990) . These authors estimated in 3 - 6 x 10'5 g the 

biomass carbon burned annually, corresponding to 24 - 57 x 10'2 g of biomass 

nitrogen. Lobert et al (1990), based in these estimates, reported an acetonitrile 

emission from biomass burning to the atmosphere equivalent to 410,000 - 2,220,000 

tonnes/year. Hamm and Warneck (1990) estimated an emission of 850,000 

tonnes/year, which is in the same range, while the emission reported by Arijs and 

Brasseur (1986) of 24,000 - 174,000 tonnes/year is smaller. According with these 

estimates, a global acetonitrile release from biomass burning of 24,000 - 2,200,000 

tonnes/year can be estimated. Assuming that 10% of this release can take place in 

Europe, a continental estimate of 2,400 - 222,000 tonnes of acetonitrile release per 

year from biomass burning can be considered . This corresponds to about 8 - 740 

tonnes/day for the EU. The release at regional level can be estimated in one tenth, 

which corresponds to 0.8 - 74 tonnes/day. 

-13- 
b) Automobile exhaust 

Various nitrogen compounds, including acetonitrile and hydrocyanic acid, have 

been identified as combustion products (Schuchmann and Laidler, 1972). The global 

release of acetonitrile from automobile exhaust has been estimated in 80,000 

tonnes/year by Arijs and Brasseur (1986) . Dulson (1978) reported that exhaust gases 

from gasoline-powered engines contained 1 .32% by mass acetonitrile . Assuming an 

emission of 617,400 VOC tonnes/year at one area (UK) and a content of 1 .39'o by 

mass acetonitrile, the release of acetonitrile from motor exhaust would be 6,359 

tonnes/year, equivalent to 21 tonnes/day . The overall amount for the EU, considering 

a population ratio of 6, would be 126 tonnes/day . 

These releases from motor exhaust are likely to be overestimates, due to the 

use of diesel in a significant number of cars and the use of new technologies, such 

as catalytic converters, utilized to reduce emissions from automobiles. 
Table 3.5. Summary of release estimates 

Source Main 

compartment 

Amount/site 

kg/day 

Amount/regional 

kg/day 

Amount/EU 

kg/day 

Production Air 83/256.6' 83.3/256 .6' 250/769.82 

W.Water 50 50 150 

Soil 1 .7 1 .7 5 

Use 

Pharm.lnd. Air 8.3 8.3 25 

W.Water 58.3 58.3 175 

Soil 0.8 0.8 2.5 

Use 

Butad. Prod. Air 2.5 2.5 7.5 

W.Water 17.5 17.5 52 

Soil 0.25 0.25 0.75 

Other uses Air 5.8 5.8 17.5 

W.Water 40.8 40.8 122.5 

Soil 0.6 0.6 1 .8 

Disp. sourc. : 

Biomass bur. 

Motor exh. 

Air 

Air 

- 

- 

800-74,000 

21,000 

8,000- 740,000 

126,000 

Total Air - 22,000-95,000 135,000-866,000 

W.Water - 166.6 500 

Soil - 3.35 10 

' emission data provided by industry 

2 calculated from emission data (3 x 256.6 kg/day per site) 

3.1 .0.2. Degradation 

3.1 .0.2.1 . Abiotic degradation 

a) Air 

The maximum of absorption for acetonitrile in the IJV range is lower than 160 

nm , therefore direct photolysis of acetonitrile in the atmosphere is not expected to be 

an important fate process (Silverstein and Bassler, 1967; Howard, 1991) . 

-15- 
Acetonitrile is reactive to oxidising materials and compounds in the atmosphere, 

being the reaction with hydroxyl radicals quoted as one of the main mechanisms for 

its removal from the environment (Lobert et al ., 1990) . The rate constant for the 

reaction of acetonitrile with hydroxyl radicals has been determined by several authors 

to range from 1 .9 - 4.94 x 10-'° cm3. molec-' . sec-' for the temperature range 20-

274C. In a moderately polluted atmosphere, with a mean concentration of 10' hydroxyl 

radicals/cm3, the calculated half-life was about 20 days (Atkinson, 1985; Guesten et 

al ., 1981 ; Gusten et al ., 1984; Harris et al . 1981 ; Wallington et al ., 1988, Lyman et al ., 

1982) . The Arrhenius activation energy, as determined by Harris et al (1981), was 

1500 cal . mole-' . 

In conditions of an average tropospheric OH radical concentration, [OH]= 5 x 

105 cm-3, Kl6pffer et al .(1988) obtained a half-life about 10 times longer, t 2>160 days. 

Acetonitrile reaction with chlorine radicals is not thought to be significant in relation to 

hydroxyl radical reaction (Arijs et al ., 1983) . 

The reaction of acetonitrile with ozone is slow, with a reported reaction rate 

constant of s1 .5 x 10-'9 cm3. molec ' . sec'' (Harris et al., 1981), .which will yield a 

half-life of z54 days, considering an average ozone abundance of 1 x 10'2 molec%m3 

(Munshi et al ., 1989) . A reaction rate constant between acetonitrile and single oxygen of 2.4 x 10-'e 

cm 3 . molec'' . sec'' has been reported (Graedel, 1978), which yields an atmospheric 

half-life of >5000 years. 

An overall half-life for acetonitrile in the troposphere of about 42 days has been 

estimated, considering both the OH radical and ozone reaction rate constants 

(USEPA, 1987). 

b) Water 

The hydrolysis of acetonitrile is unimportant for the aquatic fate of this compound at 

the normal pH range of natural waters (Ellington et al ., 1988) . The half-life for 

acetonitrile in water has been estimated to be >150,000 years based on a hydrolysis 

rate constant at ph 7 and 25°C of 5.8 x 10-3 M-' hour-' (Howard, 1991) . 

3.1 .0.2 .2. Biodegradation 

Ludzack et al . (1958 and 1959) studied the biodegradation of acetonitrile in 

Ohio river water under aerobic conditions, by measuring C02 nroduction. An initial 

assay with a dose of 10 mg/I acetonitrile needed about 21 days for reaching 75% of 

theoretical oxidation, while repeated dose studies showed the acclimatization of 

microorganisms and the oxidation rate was 5 times quicker in the second serial 

feeding . The effect of temperature on biodegradation showed that the rate of 

assimilation observed at 5°C was about a fifth of that at 20°C. The study with aged 

sewage showed that degradation in the sewage was slower than in the river water. 

Sasaki (1978), using the Japanese MITI (Ministry of International Trade and Industry) 

test, reported acetonitrile as readily biodegradable, being degradation higher than 98% 

after 28 days and higher than 30% in 2 weeks . The available biodegradation test 

results for acetonitrile are summarised in Table 3 .6 . 

-16- 
Although there are not biodegradation studies following OECD guidelines all the 

available information suggests that acetonitrile can be considered as readily 

biodegradable . 

Table 3.6. Biodegradation test results for acetonitrile 

ype 

yp 

TT 

e Source of Method Result Detection Ref 

microorganisms 

ic 

aerobic 

[ 

activated sludge other 17% 02demand 1 

1 day 

ro 

jc 

aerobic river water other 100% 02 demand 1 

4day 

aerobic other other 98% OZ demand 1 

28day 

aerobic activated APHAe >58% 02 demand 2 

sludge,adapted 5day 

BOD/ThOD 

aerobic other Directiveb 30% OZ demand 3 

14day 

BOD/ThOD 

anaerobic - other half-life - 4 

4-16weeks 

e American Public Health Association 1980 

° Directive 84/449/EEC .C7 

1 Ludzack and Ettinger 1960 

2 Babeu and Vaishnav 1987 

3 Envirofate 1994 

4 Howard 1991 

Several authors have isolated a number of genera and individual strains of 

bacte-:a able to grow on acetonitrile under aerobic conditions. Mimura et al (1969) 

isolated the bacterium 

Corynebacterium nitrilophius from activated sludge and reported the ability of this 

microorganism to assimilate acetonitrile . Asano et al (1980) identified 

Arthrobacter sp. J-1 as being capable of growth on acetonitrile . Goud et al (1985) 

isolated bacteria from a sewage treatment plant at a petrochemical industry and found 

that Azobacter and Pseudomonas isolates were able to grow well on acetonitrile . 

Various bacteria isolates from soil capable of degrading acetonitrile have also been 

reported (Nawaz et al ., 1989; Li et al ., 1991 ; Martinkova et al ., 1992 ; Chapatwala et 

al ., 1992) . 

-17- 
3.1 .0.3. Distribution 

Acetonitrile is a volatile liquid with a vapour pressure of 9,864 Pa at 20°C 

(Verschueren, 1983) and it is expected a rapid volatilisation of this compound to the 

atmosphere when released to the environment. 

The Henry's Law constant of 2.07-2.6 Pa. m3. mole-' (Snider and Dawson, 

1985; Hine and Mookerjee, 1975) indicates that volatilisation of acetonitrile from 

surface waters and moist soils is likely to be significant (Howard , 1993) . Chen et al 

(1981) reported a decrease to 5% of the original acetonitrile level in river water after 

72h. 

The removal of acetonitrile from the atmosphere by precipitation has been 

quoted in several reports as one of the main fate processes for this compound, as 

important as the photo-oxidation reaction with hydroxyl radicals (Hamm et al., 1989; 

Hamm and Wameck, 1990) . A residence time of about 3 years has been estimated 

for acetonitrile in the troposphere due to wet deposition (Hamm et al ., 1984; Arijs and 

Brasseuur, 1986) . 

An overall residence time for acetonitrile near 1 .5 years was calculated considering the 

two principal removal processes, precipitation and reaction with hydroxyl radicals 

(Hamm and Wameck, 1990; Arijs and Brasseur, 1986). Nevertheless, a shorter 

residence time was calculated based on the tropospheric mass balance of this 

compound (Hamm and Wameck, 1990). They estimated a mass content (G) in the 

troposphere of 370-570 x 103 tonnes acetonitrile and a global source strength (Q) of 

600-1,100 x 103 tonnes acetonitrile / year, which would yield an overall residence 

time, calculated as G/Q, of 0.23-0.95 years. The dissolution in the ocean was 

proposed as an effective process for acetonitrile removal, that would take up 659'0 of 

the total acetonitrile emission, and the combined residence time for the process 

(precipitation, hydroxyl radical reaction and ocean dissolution) was estimated to be of 

0.45 years, which is in agreement with the mass balance estimate. 

The adsorption coefficient, Koc, can be estimated for acetonitrile using the 

octanol-water partition coefficient, log Pow -0.34 (Leo et al ., 1971), and FCo, values 

of 0.3-16 1/kg were obtained using regression equations reported in Lyman et al 

(1982) . These Koc values indicate a low potential for adsorption and then leaching of 

acetonitrile to groundwater may be important when spilled on soil (Howard, 1993) . 

3.1 .0.4. Accumulation 

No experimental data on bioaccumulation are available. A bioconcentration 

factor for fish of 0.3 1/kg was calculated using the log Po,, = -0.34 value and regression 

equations defined in Lyman et al (1982) . This bioconcentration factor is in agreement 

with other calculated values which are in the range of 0 .3-0.4 (EPA ; 1991) and 

indicates a lack of bioaccumulation potential in the environment. 

3.1 .1 . Aquatic compartment (incl . sediment) 

3.1 .1 .1 . Calculation of Predicted Environmental Concentrations 

-18- 
a) PEC local 

Only emission data to the aquatic compartment from the use of acetonitrile 

have been provided by industry . An aqueous discharge of 4.70 tonnes/year, 

corresponding to 15.7 kg/day, has been reported . Therefore, the PEC,,, for water has been calculated using the equations given 

in the Technical Guidance Document, assuming that the release occurs to a waste 

water treatment plant. 

PEC,.w(.,e,) = Ceff / (1 + KP(..P~ . C.P) . D [g/I] 

where: 

Ceff = concentration of the chemical in the WWTP effluent [g/I] 

KP(,ap) = Kw x f,,,$,,p = FC= x 0.1 = 16 x 0.1 = 1 .6 (1/kg) 

C W = concentration of suspended matter in the river = 15 mg/I = 15 x 10-6 kg/I 

D = dilution factor = 10 

The WWTP effluent concentration is calculated using the following equation : 

Ceff=W .(100-P)/100 .Q 

where : 

W = emission rate (kg/day) 

Q = volume of waste water (m3/day) = 2000 M3 /day 

P = percentage removal in the WWTP (%) = 91% 

Acetonitrile is readily biodegradable under aerobic conditions and using the 

tables in Appendix II of TGD based on the SIMPLETREAT model, log PoW = -0 .34 

and log H = 0.41, the removal of acetonitrile in the WWTP is 91%. The fate of 

acetonitrile in the WWTP is 91% degraded and 9% dissolved in water. 

The release of acetonitrile to waste water during production was estimated in 

50 kg/day, Table 3.5. 

Ceff = 50 x 9 / 100 . 2000 = 2.25 x 10-3 g/I 

PECIocw(Wate, - 2.25 . 10-3 / (1 + 1 .6 . 15 . 10-6) . 10 = 2.25 . 10-3 / 10 .00024 = 

0.225 . 10-~ g/I = 225 Ng/1 

Acetonitrile is used in various processes in the chemical industry . The highest 

percentage is used in the pharmaceutical industry, assuming that this volume (50% 

x 5,000 tonnes) is used in one site, the release of acetonitrile to water would be 58 .3 

kg/day, Table 3.5 . 

-19- 
Ceff = 58 .3 . 9 / 100 . 2000 = 2.62 . 10-3 g/I 

PEC,oca,(we,er) = 2.62 . 

10-3/ 10.00024 = 2.62 . 10"3 g/I = 262 E1g/I 

This value will be used as- the worst case PECbca,(eter)~ 

Other important percentage (15°/a) is used in butadiene production . Assuming 

that this volume is used in one site, the release of acetonitrile to water will be 17.5 

kg/day, Table 3.5 . Ceff = 17.5 . 9 / 100 . 2000 = 0.788 .10-3 g/I 

PEC,.w(er) = 0.788 . 10-3 /10.00024 = 0.0787 . 10-3 g/I = 78 .7jjg/I 

Table 3.7 shows the PEC,=,,(a,er) calculated for the aquatic environment. 

Table 3.7. Local PECs for the aquatic environment 

Process Release to waste Ceff (ug/I) PECbC,, 

water (kg/day) (Ng/I) 

Production of 50 2,250 225 

acetonitrile 

Pharmaceutical 58.3 2,620 262 

industry 

Butadiene 17 .5 788 78.7 

production 

The PECbcw(s,d) can be calculated using the equations given in the TGD and the values 

for PECwcai(water)~ 

PECIO~(sed) = lew + Kp(sed) ~ es ~ Psoud / Psed l . PECIocW(water) g/kg 

where 

ew =volume fraction of pore water of moistened sediment = 0 .8 I/I 

es = volume fraction of solids of moistened sediment = 0.2 I/I 

Psolw = density of dry weight solid phase = 2 .5 kg/I 

Psed =density of moistened sediment = 1 .3 kg/I 

K,(sed) = sediment / water partition coefficient 

Kplsedl = foc X Koc + foc(sed) = 0.05 

-20- 
Kp(s,d) = 0.05 x 16 = 0.8 I/kg 

Using this equation and the various PECs local (water) calculated above, the PECs 

local (sed) have been calculated and are shown in Table 3.8. 

Table 3.8. Local PECs for sediment 

Process PEC,,~ ,,,e,Fcg/I PECWIWSea Ng/kg 

Production of 

acetonitrile 

225 249.2 

Pharmaceutical 

industry 

262 290.2 

Butadiene 78.7 87.2 

b) PEC regional and PEC continental 

The calculation of predicted regional and continental environmental 

concentrations of acetonitrile has been done using the Mackays model Level I . A 

summary of the results are shown in Table 3.9. 

Table 3.9. Summary of regional and continental modelling 

Regional Continental 

Amount released 2,314,251 21,096,224 

moles/day 

Concentration in air (Ug/m3) 2.3 0.36 

Concentration in surface 1 .03 0.16 

water (Ng/I) 

Concentration in sediment 7.7 1 .19 

(ng/kg) 

Concentration in soil 3.9 0.59 

(ng/kg) 

Molecular weight = 41 .05, vapour pressure = 9,864 Pa at 20°C, water solubility = 

74,000 g/m3 at 25°C and log Ko,,, = -0.34 
3.1 .1 .2. Measured levels 

Table 3.10. Levels of acetonitrile in water and sediment 

Country Location Sample Concentration 

USA Rock Sprigs, Wyoming Retort water', shale 42 Ng/I 

oil processing 

Hanna, Wyoming Process water`, 620 jrgll 

coal gasifica6on 

plant 

Gillette, Wyoming Process water, 1,246 jrg/I 

coal gasification 

plant 

Colorado Waste water", shale 23-43 mg/1 

oil retorting 

Coal gasification 365 mg/I 

condensate` 

Tucson, Arizona Rainfall' 0.18 pg/I 

E Japan 47 Prefectures . Sediment' 0.021 - 0.54 mg/kg 

e Izzarl e ., 

b Benton, 1992 

c Mohr and King, 1985 

° Snider and Dawson, 1985 

° Office of Heath Studies, 1990 

No data on measured levels in water or sediment was found for european 

countries. 

Acetonitrile concentration found in water and sediment samples in USA and 

Japan are shown in Table 3 .10 . Acetonitrile levels were determined in aqueous 

samples collected from different operations related with shale oil processing and coal 

gasification in USA. A japanese environment agency made a study on acetonitrile in 

fresh and marine surface waters across Japan (Office of Health Studies, 1991). In this 

study, acetonitrile was not detected in surface water (limit of detection 3 Mg/I) but was 

detected in sediment with a frequency of 11 out of 60 samples. In addition, acetonitrile 

was detected in four rainfall samples collected at a rural site in Tucson, Arizona 

(Snider and Dawson, 1985) . 

3.1 .1 .3. Comparison of PECs with measured levels 

The local PECs calculated for surface water ranged from 78 .5 to 262 /rg/I at 

acetonitrile production or use sites and the acetonitrile concentration in NWWfP 

effluents (Ceff) ranged from 0.79 to 2.6 mg/I . These values are in the lower range of 

-22- 
those reported in the literature for acetonitrile levels in waste water of various industrial 

processes in USA, ranging from 0.04 to 365 mg/I, Table 3.10. In relation with sediment 

levels, acetonitrile was found in Japan at concentrations between 21 and 540 pg/kg, 

which are in agreement with values calculated for local PECsed, which range from 87.2 

to 290.2 pg/kg. 

3.1 .2. Terrestrial compartment 

3.1 .2.1 . Calculation of Predicted Environmental Concentration 

Direct emissions of acetonitrile to soil from point sources are small and have 

been estimated in 1 .7 kg/day at production sites and to range from 0.25 to 0.8 kg/day 

from various uses of acetonitrile, Table 3.5 . 

Predicted concentrations of acetonitrile in soil have been calculated using 

Mackay's model, Level I . The PEC regional obtained for soil was 3.9 ng/kg and the 

PEC continental was 0.59 ng/kg, Table 3.9 . 

The PEC for soil porewater has been calculated using the equation in the TGD: 

PECso;tPorewete, _ (PECsoa . psoit ) / (ew + Kp(saq . es ~ Psotin ) 

where : 

Kp(soil) = soil / water partition coefficient 

K%,(, .,) = f., x K. ; f., = 0.02 

Kv(soiq = 0.02 . 16 = 0 .32 I/kg 

ew = volume fraction of pore water in soil = 0.4 I/I 

es = volume fraction of solids in soil = 0 .4 I/I 

Pso;, = density of bulk soil = 1 .5 kg/1 

Pso,ia = density of solid phase = 2.5 kg/I 

This equation and the PECs calculated above have been used to calculate a 

PEC for the soil porewater. 

PECregionai soil porewater =3.9 . 1 .5/0.4 + 0.32 . 0.4 . 2.5 = 8 .1 ng/I 

PECcontinental soil porewater= 0 .59 . 1 .5/0.4 + 0.32 . 0 .4 . 2.5 = 1 .2 ng/I 

3.1 .2 .2 . Measured levels 

No information on measured levels in soil was found . 

-23- 
3.1 .3. Atmosphere 

3.1 .3.1 . Calculation of Predicted Environmental Concentrations 

The major releases of acetonitrile to the atmosphere are from biomass burning 

and motor exhaust, Table 3.5. 

A PEC local for air for acetonitrile emissions from production and various uses can be 

calculated by using the equation given in the TGD: 

C.;, = Emission . CM W, 

where: 

C,;, = air concentration at 100 m from a point source (kg/m3) 

Emission = emission rate to air (kg/s) 

C,w,;, = standard concentration in air at source strength of 

1 kg/s = 24 . 10-e kg/m3 

Using this equation and emissions from production and use given in Table 3.5, 

various PECs have been calculated and are given in Table 3.11 . 
Table 3.11 . Local PECs calculated for the atmospheric environment 

Source Emission to air 

Kg/day 

PEC local 

Ng/m3 

Production 256.6 71 .3 

Use in Pharmaceutical 

Industry 

8.3 2.3 

Use in Butadiene Production 2.5 0.7 

Other uses 5. 8 1 .6 

Mackay's model, Level I, has been used to calculate regional and continental 

{ concentrations. The PEC regional obtained for air was 2.3 pg/m3 and the PEC 

continental was 0.36 Ng/m3, Table 3.9. 

3.1 .3.2. Measured levels 

Levels of acetonitrile in air have been determined in the atmosphere over 

Europe (Table 3.12) and other parts of the world (Table 3.13) . Some of these results 

show the contribution of biomass burning to the atmospheric levels in rural areas 

(Becker and lonescu, 1982) and also over the Atlantic Ocean, where the tendency of 

levels to be higher around the equator (Hamm and Wameck, 1990) can be explained 

by the high percentage of the world's biomass burning that takes place in the tropics, 

estimated in more than 80% by Lobert et al . (1990) . 

3.1 .3.3. Comparison of PECs with measured levels 

The local PECs calculated for air ranged from 0.7 to 71 .3 Ng/m3 at acetonitrile 

use or production sites . These values are in agreement with those reported in the 

literature for acetonitrile levels in urban and rural areas in Europe, which ranged from 

0.2 to 58.6 Ng/m3, Table 3.12. 

The calculated regional PEC is also in agreement with values reported for a 

mountain area in Switzerland (3.7 to 4.9 pg/m3) and the estimated continental PEC is 

similar, although somewhat higher, than values reported for the atmosphere of the 

Atlantic Ocean near Europe (0.035 to 0.138 Ng/m3). 
Table 3.12. Levels of acetonitrile in the European atmosphere 

Location / Sample Concentration (ng/m3) Reference 

Rural area, Germany 5,210 - 10,420 Becker and lonescu, 

1982 

Rural area, Germany 

before agric. burning 

during agric. burning 

6,720 

58,630 

Urban area, Wupertal, 

Germany 

12,430 ± 4,030 

Coastal area, Ireland 10,420 

Mountain area, Switzerland 

3,700 - 4,870 

Urban area, Mainz, Germany 197-1,453 Hamm and Wameck, 

1990 

North sea 109-328 

Deuselbach 197 - 279 FI'amm et al ., 1989 

Aircraft flight over Germany 218-260 

Aircraft flight over Scandinavia 186-341 

Table 3.13. Levels of acetonitrile In the atmosphere of other countries 

Location / Sample Concentration (ng/m3) Reference 

Rural area, Arizona, USA 94.1 ± 33.6 Snider and Dawson, 

1984 

Samples collected across 210-42,000 Office of Health 

Japan Studies, 1991 

Atlantic Ocean 30-17°S 122-192 Hamm and Warneck, 

14°S-Eq 208-302 1990 

Eq-160N 170 -257 

22-50°N I 35 - 138 I 
3.2 . Effects assessment 

Hazard identification and Dose (concentration) - response (effect) 

assessment 

3.2.1 . Aquatic compartment (incl . sediment) 

3.2.1 .1 . Aquatic organisms 

The provided information includes a set of data on the acute toxicity of 

acetonitrile for aquatic organisms . These data have been summarized in Tables 3.14, 

3.15 and 3.16. It has not been possible to check ail data going back to the original 

publications . Therefore, unless otherwise stated, references must be considered as 

indirect references from the IUCLID data base and the additional background 

documents presented for the assessment. 

The acute toxicity of acetonitrile on fish has been assessed on different species. 

The IUCLID data base includes values for Pimephales promelas, Lepomis 

macrochirus, Leuciscus idus melanotus, Poecilla reticulata and Oryzias latipes. The 

lowest value is the 48 h TLm for Oryzias latipes, 730 mg/I, while all 48-96 h LC50 

values are in the g/L range. Information on additional fish species can be obtained 

from other sources. The WHO report (1993) includes 14 acute LC60 values on seven 

fish species. Significant values are 24-48 h LC50 values higher than 1 g/L for Oryzias 

latipes, and two 48 h LC50s, 730 and 880 mg/L on Cyprinus carpio and 

Ctenopharyngodon idellus respectively . The data set includes flow through and static 

tests as well as different water pH and hardness conditions . Relevant differences on 

acetonitrile toxicity regarding water quality conditions were not observed . 

The acute toxicity of acetonitrile on aquatic invertebrates was investigated by 

Ewell et al. (1986) on six species from different taxonomic groups including 

Arthropoda, Platyhelminthes, Mollusca and Annelida; all LCSO values were reported as 

> 100 mg/L. Additional data reported by IUCLID on Daphnia pulex, Culex restuans, 

Hyalella azteca and Palaemonetes kadiakensis are in the g/L range. 

A reduced number of toxicity results on algae has been found . Toxicity 

threshold based on the first detectable inhibition of cell multiplication for the green alga 

Scenedesmus quadricauda and for the blue-green algae Microcystis aeruginosa has 

been reported as 7300 and 520 mg/L respectively . No ECSO values have been found . 
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information provided for the inhibition of algal growth does not include NOEC 

calculations or enough data for these estimations. Thus, the effect assessment 

focuses exclusively on acute toxicity data. 

The lowest L(E)C50 figure is the 48 h LCSO on Cyprinus carpio, 730 mg/L. The 

TTs for algae are in the same range. Therefore, it seems appropriate in this 

assessment to consider 730 mg/L as the lowest end of the acute toxicity range for 

aquatic organisms. This range covers three taxonomic groups, fish, invertebrates and 

algae, and taking into account the lack of chronic figures, the recommendations of the 

Technical Guidance Document suggest the application of the factor 1000 to the lowest 

end of the acute toxicity range (730 mg/I), obtaining a PNEC for aquatic organisms of 

0.73 mg/I. 

PNEC,q ,bc ,ro ,,==1owest end acute toxicity range/1000=0.73 mg/11 

The data set only includes freshwater species. Therefore, in absence of data 

on saltwater species the above PNEC can be used for both, freshwater and marine 

environments, while data on marine species are produced. 

3.2.1 .2 . Effects on microorganisms 

The toxicity of acetonitrile on microorganisms (table 3.17) has been previously 

reviewed by different authors. Blum and Speece (1991) present data on three types 

of environmental bacteria that can be relevant when considering the microbial activity 

of domestic VWfPs. The IC50 values (the concentrations of acetonitrile causing 50% 

bacterial inhibition compared to controls) were summarized in the internal report by 

Nielsen and Howe as follows: 

1 . Aerobic heterotrophs.- These bacteria predominate in activate sludge 

systems and in natural aerobic environments where they convert organic 

material to carbon dioxide and water. The inhibition in oxygen uptake by the 

bacteria was monitored after 15 hours exposure and used to calculate and IC50 

of 7500 mg/L. 

2. Nitrosomas sp.- These bacteria convert ammonia nitrogen to nitrite as the 

first most sensitive step in the biological oxidation of inorganic nitrogen. The 

inhibition in ammonia consumption by the bacteria was monitored after 24 

hours exposure and used to calculate an IC5. of 73 mg/L. 

3. Methanogens.- Methanogens form part of the consortium of bacteria that 

convert organic matter to carbon dioxide and methane under anaerobic 

conditions . The inhibition of gas production by the bacteria was monitored after 

48 hours exposure and used to calculate an ICso of 28000 mg/L. 

-31- 
Additional data on Nitrosomas sp, Nocardia rhodochrous, Pseudomona pufida, 

and P. aeruginosa agree with this range of effects, from more than 100 mg/I to several 

g/L. According to the data set presented by IUCLID, this range also covem the toxicity 

data obtained for Protozca species. 

The recommendations of the Technical Guidance Document suggest the 

application of the factor 1 if the test has been performed with nitrifying bacteria, and 

a factor 100 for the EC50 obtained using respiration inhibition or similar endpoints. The 

value obtained for the most sensitive test on nitrifying bacteria, 73 mg/L, agrees with 

the application of the factor 100 to the inhibition of oxygen uptake by aerobic 

heterotrophs, which produces a figure of 75 mg/L. Thus a PNECm;c,oo,9anis ,S of 73 mg/L 

is proposed in this assessment. 

PNECm,a ,9 ,,w = 73 mg/L 
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3.2.1 .3 . Effects assessment for the sediment 

The available data set includes a single data on the effect of acetonitrile on the 

sediment organism Hyalella azteca, but for waterborne exposure. The ECSO obtained 

for this organism is similar to that reported for other aquatic invertebrates suggesting 

that the first assumption of the partitioning method presented by the Technical 

Guidance Document can be accepted. In addition, the very low Pow of acetonitriie, 

indicates that the use of water phase as the single via for uptake is also adequate . 

Thus, the PNEC may provisionally be calculated using the equilibrium partitioning 

method with the PNEC for aquatic organisms and the sediment/water partitioning 

coefficient. 

PNEC a. = Kp(s n .PNEC,y , . .,ro ,,sms 

A rapid estimation produces a Kp(sed) value of 0.8 I/Kg thus, the PNEC value 

for sediment-dwelling organisms should be 0.58 mg/Kg. 

PNEC d=Kp( M.PNEC,q tjc aq ,,, s= 0.8 I/Kg x 0,73 mg/L= 0.58 mg/Kg. 

3.2.2 . Terrestrial compartment i 

The available data set does not include a single data for th~e terrestrial 

compartment other than those on mammals which would be used for the assessment 

of secondary poisoning. 

Taken into account the lack of data, and according to the Technical Guidance 

Document, the equilibrium partitioning method can be applied as a conservative 

calculation method to identify a potential risk to the soil compartment. The PNECaquat;c 

organisms, is used for the risk assessment, thus, no additional effect estimations are 

required . 

3.2.3. Air compartment 

There are not data for this assessment. 

3.2.4. Non compartment specific effects relevant to the food chain (secondary 

poisoning) 

According to the Technical Guidance Document, the risk characterization for 

secondary poisoning is required if three specific criteria are fulfilled . 

These criteria can be summarized as : 

Indirect exposure likely . 

Indication of bioaccumulation potential and 

-34- 
Mammalian toxicity risk . 

In the case of acetonitrile, it is toxic for mammalian, but your low potential for 

bioaccumulation indicates that secondary poisonings are of low concern. 

3.3. Risk characterization 

3.3.1 . Aquatic compartment (including sediments) 

The worst case PEC/PNEC ratios are summarized in tables for water column 

and for sediments respectively . 

Table 3.18. :PEC/PNEC ratios for the aquatic compartment: water column 

WATER PEC PNEC PEC/PNEC 

LOCAL 262 ~tg/I 730 pg/I 0.36 

REGIONAL 1 .03 pg/I 730 pg/I 0.0014 

CONTINENTAL 0.16 pg/I 730 Ng/I 0.00022 

Table 3.19. : PEC/PNEC ratios for the aquatic compartment: sediment 

SEDIMENT PEC PNEC PEC/PNEC 

LOCAL 290 Mg/Kg 580 pg/Kg 0.5 R 

10 

EGIONAL 0 .007 pg/Kg 580 pg/Kg 0.000013 

I 

CO 

TI 

CONTINENTAL 0 .00 1 2 pg/Kg 580 pg/Kg 0.000002 

In all cases, for both water and sediments, PEC/PNEC ratios are below , 

therefore, it should be considered that for the aquatic compartment, including 

sediment, the risk characterization indicates that the present risk of acetonitrile for the 

aquatic environment is not of concern. 

The concentration of acetonitrile in the effluent of 1NWTP has been estimated 

in a range between 0.78 and 2.62 mg/I . The worst case assumption corresponds to 

the pharmaceutical industry . The removal acetonitrile inflow concentration should be 

about 30 mg/I . This value is lower than the estimated PNECm;croor9anisms of 73 mg/I . 

Therefore, no significant risk for NWWfP must be expected . 
Result 

For the aquatic compartment, including water, sediments and biological 

processes of VWWTP: 

ii) There is at present no need for further information and/or testing and no need 

for risk reduction measures beyond those which are being applied already. 

The data set only includes freshwater species. Therefore, in absence of data 

on saltwater species the above result can be used for both, freshwater and 

marine environments. 

3.3.2 . Terrestrial compartment 

The data set does not include a single data on terrestrial organisms. Therefore, 

only the comparisons of PEC soil/pore water versus PNEC aquatic organisms are 

possible. These results are summarized in table 3.20. 

Table 3.20. : PEC/PNEC ratios for the terrestrial compartment: 

soil porewater 

SOIL 

POREWATER 

PEC PNEC PEC/PNEC 

LOCAL 

REGIONAL 0.0081 Ng/I 730 pg/I 0.00001 

CONTINENTAL 0 .0012 Ng/I 730 Etg/I 0.0000016 

These ratios are low enough to consider that the risk for terrestrial organisms 

at the regional and continental level is of low concern . 

Result 

For the terrestrial environment, at the regional and continental levels : 

(ii) There is at present no need for further information and/or testing and no need 

for risk reduction measures beyond those which are being applied already . 

This assessment does not include the local scale . 

3.3.3. Atmosphere 

There is not information on the effect of atmospheric exposures on organisms, 

other than those data considered for the assessment of potential effect on human 

-36- 
health. 

3.3.4. Non compartment specific effects relevant for the food chain (secondary 

poisoning) 

The low potential of acetonitrile for bioaccumulation indicates that secondary 

poisonings are of low concern. 

Result 

(ii) There is at present no need for further information and/or testing and no need 

for risk reduction measures beyond those which are being applied already. 
4. HUMAN HEALTH 

4.1 . Human health toxicity 

4.1 .1 . Exposure assessment 

4.1 .1 .0. General discussion 

Acetonitrile is a volatile liquid with a high water solubility . It is readily absorbed 

from the gastrointestinal tract and through the skin and lungs. All three routes of 

exposure have been reported to lead to systemic effects. 

There is little information, if any, on acetonitrile absorption in humans. However, 

human poisoning cases indicate that it is well absorbed by all routes. 

4.1 .1 .1 . Occupational exposure 

Occupational exposure to acetonitrile occur primarily through inhalation of 

vapours. Absorption through the skin may occur. 

Acetonitrile is produced as a by-product of acrylonitrile manufacture . It is a 

highly polar solvent with a high dielectric constant. 

It is used : 

in the petrochemical industry for separating olefin-diolefin mixtures and 

C4-hydrocarbons. 

to extract fatty acids from animal and vegetable oils . 

for extractive distillation, crystallization, as a starting material or 

intermediate of vitamins, steroids, bactericides and pesticide 

manufacture. 

due to its superior solvency with polymers it is used as a solvent for 

spinning fibers and casting and molding plastics. 

in the manufacture of photographic film . 

it is a common laboratory solvent, and is widely used for HPLC and as 

a solvent for DNA synthesis and peptide sequencing . 

Synthesis of acetonitrile is carried out in a closed system . Therefore, 

occupational exposure during production could only occur accidentally . For some 

industrial processes as well as when it is used in the laboratories, acetonitrile is used 

in open systems where its high volatility and relatively high odour threshold favor 

-38- 
worker exposure potential . 

The different systems of limit values are summarized in the table 4.1 . : 

Table 4.1 . : Different systems of limit values 

Country OEL-occupational 

expos.limit (8h . 

TWA) 

STEL-short term 

exposure 

limit 

Skin 

notation 

PPM mg/m3 ppm mg/m3 

U.S.A. (ACGIH, 

OSHA) 

40 67 60 101 no 

Austria 40 70 ----- ----- no 

Belgium 40 67 60 101 yes 

Denmark 40 70 60 105 no 

Finland 40 

1 

70 60 105 no 

France 40 70 ----- ----- no 

Germany 40 70 80 140 no 

The Netherlands 40 70 ----- ----- no 

United Kingdom 40 70 60 105 no 

4.1 .1 .1 .1 Manufacture 

The european production of acetonitrile is limited to Germany and Italy, since 

the United Kingdom plant was closed for production in 1990. The number of workers 

potentially exposed to this compound during its manufacture is estimated to be about 

300-400. 

The acetonitrile is mainly obtained as a by-product of acrylonitrile manufacture 

via propylene ammoxidation . The process is carried out in a closed system and 

involves temperatures of 400 - 500°C. The plants are outdoor, taking advantage of 

natural ventilation. In this situation, exposure would only be accidental . The likelihood 

of such exposures increases during maintenance operations, repair of equipment, 

transferring and quality control sampling of acetonitrile . 

-39- 
The EASE model predicts that inhalation exposure to gas or vapour used in a 

closed system will be in the range of 0 - 0.1 ppm. The model also predicts that, in 

these conditions, dermal exposure will be negligible . 

High exposure may occur during activities which involves breaching the closed 

system such as sampling, maintenance and filling activities. The estimated exposure, 

according with the EASE model (non dispersive use with LEV), will be 10-50 ppm. 

However, these concentrations will be received as brief and intermittent exposures 

rather than over a full workshift. Assuming that contact was incidental, dermal 

exposure will be low. 

According to an european producer the process is continuous and automated . 

The filling operations consist on filling railway tank cars with gas exhaust pipe for 

purifying . 

The tables 4.2. and 4.3 . show the measurements made by two european 

producers: 

Table 4.2 . : Long term occupational exposure during production 

Plant Task No. Type of Repres . Comment Resp. 

location samples sampling 8h. TWA Protec 

worn? 

ste, different* 

work ---- stationary < 0.1 ppm 

position 

Italy 

sile2 differenr 

work stationary 

0.5 ppm 

position ---- 

production 2 stationary/personal < 0.0059 nortnal no 

Gerrnany production 

filiny stationary/personal < 0.0059 filling rail way no 

operations 2 tank cars 

* It is assumed that tasks where exposure is expected to be high are included as 

"different work positions" (such as filling operations, sampling and maintenance) . 
Table 4.3 . : Short term occupational exposure during production 

Plant location Task No. of Type of RepresentLtive Respiratory 

samples samples conc. (ppm) protection 

Germany Take sample stationary/ <0.0059 no 

~ of the product ~ 2 ~ personal I x 20 min 

In the worst case, the exposure level was below 0 .5 ppm. This is much lower 

than the most representative exposure limit value of 40 ppm (8h-TWA) . 

4.1 .1 .1 .2. End uses 

The actual number of persons exposed or potentially exposed to AN is 

unknown. It could be a high figure in view of the wide pattern of uses. 

Acetonitrile is used as a solvent on chemical industry . According to a producer, 

acetonitrile is handled in closed systems with the "spent" solvent being continuously 

distilled and recycled. The main use in this scenario is the extraction of 1,3 -

butadiene. 

The table 4.4 . shows measured data from three chemical companies : 

Table 4.4. : Measured data from three chemicals companies 

company task year mean exposure type of comments 

level(ppm) sampling 

sampling, 

Chemical maintenance, 1994 

company cleaning < 0.1 personal 

activities 

company 

Chemical purifying 

company ---- 1990 21" ambient acetonitrile by 

redistillation 

Chemical process work non dispersive 

company ---- use, 

laboratory 1977-91 10 dilution 

work ventilation 

* 21 ppm was the highest value found and it represents an exposure over 5 .40 

h. It is supposed that an exposure over 8 hours would be less than 21 ppm but 

we have assumed this level as representative of long-term exposure, covering 

the worst case situation . 

-41- 
In the worst case, the exposure level of 21 ppm is below the current exposure 

limit (40 ppm, 8 hour TWA) adopted by the majority of member states . No further 

details were given about job categories but it is assumed that involves activities where 

there is a need for breaching the closed system. 

Near 509'0 of the european acetonitrile production is used in pharmaceutical 

manufacturing processes. In general, acetonitrile is handled in closed reaction and 

distillation section of the plant during the manufacturing process. 

Data from HSE shows that acetonitrile was not detected in personal samples 

taken along 1988 from different job locations, in a plant manufacturing thiamine. 

The table 4.5. shows exposure data from two pharmaceutical companies. No 

details about the job categories were reported. 

Table 4.5. : Exposure data from two pharmaceutical companies 

company number of Sam- mean concentration type of sampling No . of samples with (PPm) 

ples ezposure level range 

(PPM) (PPM) <5 5-20 20-40 >40 

pharmaceutical 13 2 0-16 .8 personal/ambient 12 1 

company 

1980-1987 

pharmaceutical 45 9.42 <5 - 75 personal 40 2 3 

company 

1992 

The meaning of these measurements can only be assessed to a limited extent 

because the processes and the activities involved are not described and information 

on the duration, frequency of exposure and pattern of control is not available. 

Data from Germany collected in different companies (plastic and 

pharmaceutical) and research laboratories show that 95% of results are below 7.3 

ppm. The higher exposures (between 4.76 - 7.3 ppm) correspond to research 

laboratories where acetonitrile is used as mobile phase in chromatography . 

By analysing all measured exposure data we conclude that an exposure level 

of 20 ppm is a reasonable worst case situation, and more, taking into account that it 

has been measured in a sampling time lower than 8 hours (21 ppm x 5.40h and 16.8 

ppm x 3 h.) . Values higher than 40 ppm have been reached only in a company and 

this can be attributed to a particular situation not reflecting the general pattern (even 

in that company 90% of the samples gave results below 5 ppm) . 
For risk characterization purposes, a worst case exposure level of 20 ppm is 

considered. 

In general, most acetonitrile uses are in industrial processes (in closed reaction 

or processing systems), so that exposure is likely in special tasks such as sampling, 

maintenance and filling activities . 

Exposure could be estimated by using the same approach as in the previous 

section. Accordingly, the EASE model predicts that exposure will be in the range of 10 

- 50 ppm (non dispersive use with LEV) . These figures are in agreement with the 

measured exposure data. 

The situation can be different in laboratories where acetonitrile is used . 

Acetonitrile is fed by tube into the HPLC and the waste solvent is collected upon 

exiting the instrument, so that the likelihood of an exposure is very low. However, 

acetonitrile is usually transferred or filtered before entering the instrument and the 

likelihood of an exposure increases. 

In this situation, dilution ventilation has been chosen as pattern of control in 

research laboratories as a worst case situation . The EASE model predicts that 

exposure will be in the range of 100-200 ppm. On the other hand, these activities take 

only a few minutes not a whole shift. Therefore, the range quoted is likely to be an 

over estimate. Data from Germany show that exposures around 7 .3 ppm could be 

obtained in research laboratories where acetonitrile is used in chromatography. 

Since acetonitrile is absorbed by skin, potential exposure will occur via skin 

contact. 

Exposure is likely to occur during activities such as sampling, maintenance, 

cleaning or laboratory work. 

Assuming a non dispersive pattern of use and incidental skin contact, the EASE 

model predicts that exposure to the hands and forearms will be low, in the range of 0-

0.1 mg/cm2/day. Gloves are required in the industrial processes and in the laboratories 

for special tasks reducing the expected exposure to a minimum. 

4.1 .1 .2. Consumer exposure 

No quantitative data have been obtained for the evaluation of consumer 

exposure, neither from the chemical industry, nor through literature reviewed. 

Most of the acetonitrile produced is used in the synthesis of other substances 

within the chemical industry and does not reach consumers. 

Looking at the accidental intoxication cases to acetonitrile we could conclude 

that acetonitrile could be present in nail remover. However, acetonitrile is not on the 

EC Cosmetics Inventory (96/335/EC) and is not approved for use in cosmetics in 

Europe .Therefore it is not of concern for consumers . 

-43- 
4.1 .1 .3. Indirect exposure via the environment 

The indirect exposure is assessed by estimating the total daily intake of a 

substance based on the predicted environmental concentrations for (surface) water, 

groundwater, soil and air. The concentration of a substance in food is correlated to its 

concentration in water, soil and air and is also dependent on its bioaccumulation 

behaviour. 

Release of acetonitrile at environment can occur from production and uses as 

well as from other sources: biomass burning and automobile exhaust. 

The USES model has been used (Appendix A) . Some values are reproduced 

in table 4.6. 
Table 4.6. : Estimated human daily intake of acetonitrile 

Source Local Regional 

Air 4.45 x 10-5 0.00039 

(mg/Kg/day) 

Drinking water 7.58 x 10-6 1 .9 x 10-5 

(mg/Kg/day) 

Fish 1 .25 x 10-8 3.15 x 10-8 

(mg/Kg/day) 

Stem of plant 4.41 x 10-' 3.83 x 10'e 

(mg/Kg/day) 

Root of plant 1 .5 x 10-' 1 .02 x 10-e 

(mg/Kg/day) 

Meat 6.02 x 10-'3 5.36 x 10-12 

(mg/Kg/day) 

Milk 6.00 x 10-13 5.34 x 10-12 

(mg/Kg/day) 

Total human dose 5.27 x 10-5 0.00042 

(mg/Kg/day) 
4.1 .2 . Effects assessment 

4.1 .2.1 . Toxicokinetics, metabolism and distribution 

4.1 .2.1 .1 . Studies in animals 

In vfvo studies 

Absorption 

There are not available quantitative analytical data on the pulmonary absorption 

of acetonitrile . However, it is known that acetonitrile is easily absorbed from the lungs 

of animals exposed to acetonitrile vapour, (IPCS, 1993) 

The studies conducted by Pozzani et al ., (1959) in order to know the skin 

penetration of acetonitrile in rabbits demonstrated effective skin absorption of 

acetonitrile . 

Although there is evidence that acetonitrile is easily absorbed from the 

gastrointestinal tract, no quantitative data are available. (IPCS, 1993) . 

Distribution 

Haguenoer et al ., (1975) studied the tissue distribution of acetonitrile and its 

metabolites in Wistar rats after intraperitoneal administration of 2,340 or 1,500 mg/kg 

of the compound . Acetonitrile was found in heart, lungs, liver, spleen, kidneys, 

stomach, intestines, skin, muscle, brain and testes . Free and conjugated hydrogen 

cyanide were also detected in all studied organs. 

Whole body autoradiography with 2-'4C-acetonitrile in mice demonstrated 

heavy location of acetonitrile and its metabolites in the liver, kidney, gastrointestinal 

tract, gallbladder and urinary bladder 5 minutes after dosing. At 24 and 48 hours 

radioactivity was still retained in the liver and gastrointestinal tract. Delayed 

accumulation and retention of 2-'°C-acetonitrile was demonstrated in the male 

reproductive organs and, to a lesser extent, in the brain . (Ahmed et al ., 1992) . 

There are no indications that repeated administrations of acetonitrile result on 

its accumulation in animal tissues 

Biotransformation 

The toxicity of acetonitrile has been attributed to its metabolite cyanide (Willhite 

and Smith, 1981) which has been hypothesized to result from a cytochrome P-450-

dependent oxidation of the nitrile at the alpha carbon, and subsequent degradation of 

the intermediate cyanohydrin, (Ohkawa et al ., 1972) . 

-46- 
The results of human and animal studies indicate that cyanide formed in vivo 

is subsequently conjugate with thiosulphate to form thiocyanate, which is eliminated 

in urine. This conjugation is catalysed by the widely distributed enzyme rhodanese 

("thiosulphate cyanide sulfur transferase: EC 2.8 .1 .1) (Pozzani et al ., 1959; Silver et al ., 

1982; Willhite, 1983). 

The release of cyanide from acetonitrile and its subsequent metabolism to 

thiocyanate have been studied under a number of experimental conditions and in 

several animal species. 

Experimental studies with rats, monkeys and dogs have documented cyanide 

in the blood and thiocyanate in the urine following exposure to acetonitrile via 

inhalation or injection, (Pozzani et al ., 1959) . 

In a study with mate CD-1 mice treated with various nitriles including 

acetonitrile, WiIlhite and Smith (1981) showed that tissue concentrations of cyanide 

taken at death or sacrifice 2.5 h after injection of an ip LDso dose of certain nitriles 

were elevated in all cases, but considerable variation was noted from nitrile to nitrile. 

The livers consistently had higher concentrations of cyanide than the brains . Even 

within groups of animals given the same nitrile, there was considerable variation in the 

cyanide concentrations. The higher concentrations correlate with the more severe signs 

of intoxication . This large variation may be due to individual differences in the rate of 

cyanide liberation in vivo, to differences in the rate of cyanide`, biotransformation to 

thiocyanate or both . 

wllhite (1983) studied the in vivo biotransformation of acetonitrile in the golden 

hamsters. Non-pregnant female hamsters were given an oral dose or an 

intraperitoneal injection of 100, 200, 300 or 400 mg/kg body weight AN. The animals 

were killed 21/2 hours after dosing and the blood, brain, kidneys and liver level of 

cyanide and thiocyanate were determined . Elevated levels of cyanide and thiocyanate 

were detected in all studied tissues after both oral and intraperitoneal dosing. The liver 

t and kidneys contained greater concentrations of cyanide and thiocyanate than the 

brain, and whole blood, liver and kidney thiocyanate concentrations were up to 10 

times those in the brain. An increase in acetonitrile dose lead to in increase in 

metabolite concentrations. The pattern of biotransformation was similar regardless of 

the route of administration . 

After a single intraperitoneal administration of acetonitrile (2,340 mg/kg) in rats, 

all animals died in 3 to 12. h and acetonitrile was found to be distributed in various 

organs. The free cyanide varied from 170 pg/kg in the liver, to 3.5 mg/kg in the spleen . 

Concentrations of combined cyanide in the liver, spleen, stomach and skin were 3.6, 

13 .2, 17 .6 and 10 .5 mg/kg tissue respectively, (Haguenoer et al ., 1975) . 

Thiosulphate is an effective antidote of cyanide poisoning . Willhite and Smith 

have reported significant reduction in mortality following thiosulphate prophylaxis of 

mice exposed to letal concentrations of acetonitrile . This indicates that cyanide played 

-47- 
an important role in toxicity ; significant reductions in both mortality and the in situ 

cyanide concentrations were observed following thiosulphate prophylaxis of 

acetonitrile-injected mice. Pretreatment with a hepatotoxic dose of CCI, (a well-known 

modifier of the hepatic microsomal oxygenase system) provided significant protection 

against death from ip injection or inhalation of acetonitrile and resulted on a significant 

reduction in the in situ cyanide concentrations following treatment with acetonitrile, 

(Willhite, 1981 ; Willhite & Smith, 1981) . This indicate that there is little, if any, acute 

toxicity due to the parent nitrile itself in the absence of normal hepatic function . The 

metabolite of acetonitrile was more acutely toxic than the compound, (Willhite, 1983) . 

Ahmed and Farooqui (1982) measured cyanide levels one hour after 

administration of LD50 doses of several satured and unsatured nitriles to male 

Sprague-Dawley rats . Animals in groups of 6 were fasted overnight and a LD50 2460 

mg/Kg of acetonitrile was administered orally . Control animal received equivalent 

volume of 0.9% NaCl . Following the treatment the animals were observed for 1 h and 

then killed by decapitation . At the time of killing blood was collected by completely 

draining the decapitated animals into heparinized tubes. Liver, kidney, brain . and 

gastric content were collected, frozen immediately in liquid nitrogen and stored at -

304C until the time of analysis. The conversion of acetonitrile to cyanide proceeds at 

slower rate than that of other nitriles . In fact, one hour after acetonitrile administration, 

the blood level of cyanide was much lower than those after acute doses of other 

nitriles. Peak concentrations of blood cyanide were found 7.5 h after acetonitrile dosing 

and were comparable to those of other nitriles measured one hour after dosing. Brain 

cyanide concentration one hour after acetonitrile dosing was also lower than those 

after exposure to potassium cyanide (KCN) or other nitriles. 

Urinary excretion of thiocyanate after exposure to various nitriles indicated that 

for acetonitrile the percentage of the dose excreted was lower than for other nitriles 

even though the absolute given amount of acetonitrile, based on its oral LDso, was 

much higher. 

These data indicate that the toxicity of acetonitrile is lower than those of cyanide 

and other nitriles as we can see comparing the oral LDso value of acetonitrile (2460 

mg/kg body weight) with the oral LDso of the other nitriles (i .e . 40 mg/kg for propionitrile 

or 90 mg/kg for acrylonitrile or 10 mg/kg for potassium cyanide 1 h. after oral LD50) 

(Ahmed & Farooqui (1982) . This is most probably due to the slower 

transformation of acetonitrile to cyanide and consequently, to the more efficient 

detoxification via thiocyanate excretion. 

Ohkawa et al ., (1972), have suggested that aliphatic nitriles may be activated 

by hepatic microsomal enzyme oxidation of the carbon alpha to the cyanide group. The 

resulting cyanohydrins may be unstable in vivo (as was acetone cyanohydrin) . 

Spontaneous decomposition of the intermediate cyanohydrin could liberate free 

cyanide. 

Several lines of evidence implicate cytochrome P450 dependant enzyme system 

in the metabolism of nitriles to CN- Freeman & Hayes,(1985), in a study with rats 

pretreated with acetone (an inducer of cytochrome P-450), found that acetone 

-48- 

53 
stimulate acetonitrile metabolism when the two compound are administered 

simultaneously . They suggested that acetone potentiates acetonitrile toxicity via a 

biphasic effect on acetonitrile metabolism, consistent on, an initial inhibition followed 

by a stimulation of cyanide generation upon acetone elimination . Upon further 

characterization of this inhibition, acetone was found to fit a competitive model of 

inhibition, (Freeman $ Hayes, 1987) . 

Elimination 

Pozzani et al ., (1959) first reported the presence of cyanide in the blood and 

thiocyanate in the urine following exposure to acetonitrile via inhalation or injection. The 

studies were conducted in rats, monkeys and dogs under different experimental 

conditions : 

Fifteen male and fifteen female rats were exposed to acetonitrile vapour 

(166, 330 and 655 ppm) seven hours per day, five days per week, for a 

total of 90 days. Some thiocyanate was excreted by the rats inhaling 330 

and 166 ppm acetonitrile vapour, although the amount of thiocyanate 

excreted was not proportional to the concentration of acetonitrile inhaled . 

Thiocyanate was not completely eliminated between daily exposures, but 

was almost completely excreted during the 2.5-day rest period over 

weekends. 

Repeated inhalation studies were also performed with monkeys and dogs 

exposed to 350 ppm of acetonitrile in air, in the same manner as rats . 

The concentrations of thiocyanate in the urine of three dogs increased 

from 69 to 252 mg/1 after the 5 days inhalation period and from 60 to 114 

mg/I in the monkeys. Unlike the rats, dogs and monkeys continued to 

eliminate thiocyanate beyond the 2.5-day rest period over the weekend. 

In order to know how much of the formed thiocyanate would be excreted 

three monkeys were injected intravenously with acetonitrile (0.1 ml/kg) . 

After four to eight weeks of this injection, they were injected with sodium 

thiocyanate (1 .55 ml/kg of a 10% solution in saline) . The percentages of 

the dose excreted as thiocyanate were 12% after acetonitrile and 55% 

after sodium thiocyanate injection . It appears that more than 12 % of the 

injected acetonitrile was converted into thiocyanate. 

Haguenoer et al ., (1975) studied the elimination of acetonitrile and its 

metabolites in rats after a single dose of 600 mg/kg body weight of acetonitrile . It 

seems that the acetonitrile is almost completely excreted within four days . 

However, small amounts are found in the urine (2 .98 - 3.32% of the 

administered dose) . This is possible because there is an important elimination of 

acetonitrile via the lungs and because a part of acetonitrile is biotransformed to 

cyanide. Small quantities of free hydrocyanic acid (equivalent to 0.03-0.04% of the 

administered acetonitrile) and bound hydrocyanic acid (equivalent to 2.01-2 .60% of 

-49- 
the administered AN) were eliminated within 11 days of administration . 

Silver et al ., (1982) reported that the 24 h urinary thiocyanate excretion following 

po or ip administration of acetonitrile (30 .8 mg/kg) in rats, was 11 .8 ± 2.5 and 4.4 ± 

0.5% of the administered dose, respectively . 

Compared with the excretion of other nitriles, the lower excretion of SCN- after 

administration of acetonitrile could be explained by either its greater water solubility or 

its relatively high volatility which could result in greater elimination of the parent 

compound . In fact, a high ratio of unmetabolized nitrile relative to SCN- was reported 

in the urine of rats dosed with acetonitrile by Haguenoer et al ., (1972) . This is also 

consistent with the hypothetic slow transformation of acetonitrile to cyanide . 

In vitro studies 

The production of cyanide and thiocyanate from acetonitrile have also been 

demonstrated in a variety of "in vitro" studies, (Ohkawa et al ., 1972) . 

Ohkawa et al ., (1972), found that the amount of hydrogen cyanide released in 

mouse liver microsomal preparations was increased greatly by the addition of NADPH . 

Freeman and Hayes (1987) found that microsomal metabolism of acetonitrile to 

Cyanide was oxygen and NADPH-dependent, inactivated by heat and antagonized by 

NADH. They studied in vitro the effects of known inhibitors of cytochrome P-450-

dependent metabolic pathways, and found that carbon monoxide, metyrapone and SKF 

525-A all inhibited the metabolism of acetonitrile to cyanide . Dimethyl sulfoxide and 

ethanol were also competitive inhibitors of acetonitrile metabolism and aniline HCI 

appeared to be a mixed inhibitor. 

Tanii and Hashimoto (1986) also reported that the metabolism of acetonitrile 

was NADPH dependent and enhanced by pretreatment with ethanol . 

Cobaltic protoporphyrin 9-chloride, which has been demonstrated to deplete 

hepatic cytochrome P-450 content (Drummond & Kappas, 1982), markedly decreases 

the acetonitrile metabolism in isolated hepatocytes prepared from rats pretreated 

subcutaneously with cobalt-heme (90 Nmol/kg) 48 h. before killing, (Freeman & Hayes, 

1987) . 

It is known that acetone as well as ethanol induces hepatic cytochrome P450 

LM3a (LMeb) in rabbits. This isozyme is apparently similar to cytochrome P450 j which 

has been isolated from the hepatic microsomes of isoniazid-treated rats by Ryan et 

al ., (1985) . Since the metabolism of acetonitrile is increased in animals pretreated with 

acetone, Freeman & Hayes (1987), suggested that acetonitrile is likely metabolized by 

this cytochrome P-450 isozyme, cytochrome P-450 j (LM3a, Web) . Agents (acetone, 

ethanol, dimethyl sulfoxide and aniline) that are substrates for, or inhibitors of this 

isozyme inhibited the acetonitrile metabolism . Therefore, acetone and acetonitrile seem 

substrates for the same cytochrome P-450 isozyme. 

-50- 

55 
. 

Dahl and Waruszewski (1989), studied the metabolism of acetonitrile to cyanide 

in male Fischer-344 rats nasal and liver tissues and found that the maximum cyanide 

production rates in nanomols cyanide/mg protein/minute by nasal maxilloturbinate and 

ethmoturbinate microsomes and liver microsomes for 1 millimolar initial substrate 

concentrations were 0, 0.9 and 0.098 respectively . The authors conclude that 

detoxication of inhaled acetonitrile may occur to a substantial extent in the nasal cavity . 

4.1 .2.1 .2. Studies in humans 

Acetonitrile is well absorbed by all routes . 

Studies on smokers showed that 91 ± 49'0 of the acetonitrile inhaled in cigarette 

smoke was retained, (Dalhamn et al.,1968a) . A significant portion of acetonitrile could 

have been retained in the mouth, (Dalhamn et al ., 1968b) . 

There are no studies of oral or dermal absorption in humans; however, human 

poisoning cases indicate that acetonitrile is well absorbed by both routes . Amdur 

(1959) reported the presence of cyanide in the blood, urine and tissues, and 

thiocyanate in serum of workers accidentally exposed to acetonitrile vapour. No blood 

cyanide was found in three volunteers inhaling 40, 80 and 160 ppm of acetonitrile 

vapour for 4h, (Pozzani et al ., 1959). 

There is no specific human study describing acetonitrile biotransformation and 

elimination . However, accidental poisoning cases indicate that acetonitrile is 

biotransformed to cyanide and thiocyanate, which are then excreted from urine, (IPCS, 

1993) . 

In case of suicidal oral acetonitrile ingestion, elimination half-lives of 32 h for 

acetonitrile and 15 h for cyanide were calculated during the hospitalization of the 

patient prior to death (Michaelis et al ., 1991). 

4.1 .2 .1 .3. Summary of toxicokinetics 

Acetonitrile is well absorbed from the lungs, gastrointestinal tract and through 

the skin, although there are not available quantitative data. 

Acetonitrile has a widespread distribution . It has been found in heart, lungs, 

liver, spleen, kidneys, stomach, intestines, skin, muscle, brain and testes . Free and 

conjugated hydrogen cyanide were also detected in all the studied organs, (Haguenoer 

et al ., 1975) . 

There are no indications that repeated administrations of acetonitrile result on 

its accumulation in animal tissues . 

-51- 
The acetonitrile is metabolized to cyanide via cytochrome P-450. Firstly, a 

cyanohydrin intermediate is formed and spontaneously decomposes liberating free 

cyanide . Several studies have indicated that cyanide formed in vivo is subsequently 

conjugate with thiosulphate to form thiocyanate, which is eliminated in urine, (Willhite, 

1981 ; Willhite and Smith, 1981 ; Pozzani, 1959; Haguenoer et al ., 1975); Silver et al ., 

1982; Ohkawa et al ., 1972) . 

The cyanide is responsible for the acetonitrile toxicity . The conversion of 

acetonitrile to cyanide proceeds at a slower rate than that of other nitriles, (Ahmed & 

Farooqui, 1982) . This explains the lower toxicity of acetonitrile comparing with other 

nitriles. 

The microsomal metabolism of acetonitrile to cyanide was found to be oxygen 

and NADPH dependent, inactivated by heat and antagonized by NADH . Since the 

metabolism of acetonitrile is increased in animals pretreated with acetone, Freeman 

4 and Hayes (1987) suggested that acetonitrile is likely metabolized by the cytochrome 

P450j (LM3a, LMeb). 

Elimination of acetonitrile occurs primarily through urinary excretion of the 

unchanged compound and free and bound hydrogen cyanide. 

Pulmonary clearance of unchanged acetonitrile via exhalation is also an 

important pathway of elimination, especially at high exposure levels, (Haguenoer et al ., 

1975) . 

4.1 .2.2. Acute toxicity 

4.1 .2.2.1 . Studies in animals 

Oral 

A large number of LDso values for male and female Carworth Farms-Wistar or 

Nelson albino rats, in various assays over a five-year interval, ranged from 1 .7 to 8.5 

ml/Kg (1327-6762 mg/Kg using a density value of 0.79 g/ml) by gastric intubation. The 

males appeared to be two to four times as susceptibles as females to undiluted 

acetonitrile by this route, but this difference was not important when the animals were 

fasted overnight before intubation .ln many instances delayed deaths occurred at or, 

above the LDso dosage level. However, the highest dosage levels caused rapid deaths. 

Acetonitrile diluted in corn oil, water or 1% aqueous Tergitol 7 is apparently 

better absorbed from the intestine and in most assays is somewhat more toxic for both 

male and female rats than is the undiluted compound, (Pozzani et al ., 1959) . In the 

same study Pozzani, obtained a LDSO 0.177 ml/Kg for male guinea pigs by gastric route 

(fasted) ; the acetonitrile was undiluted. 

Significant differences in LDso values were found between 14-day-old and 

adult rats, but not between young adults (80-160g body weight) and older adults (300-

470 gr body wight) (Kimura et al ., 1971) . Male Sprague-Dawley rats in groups of 6 

-52- 
were used for studies in the young and older adult rats, groups of 6-12 rats of both 

sexes were used for the newborn and 14-day old rat toxicity studies. The acetonitrile 

was given orally via straight needle in undiluted form in nonfasted rats, and the animals 

were observed for a week following medication. LDso value of 0.2 ml/Kg was obtained 

using wealing (14-day) rats and LDso of 3.9 and 4.4 ml/Kg using young and older 

adults respectively . 

Tanii and Hashimoto (1984) studied the mechanism of acute toxicity of nitriles 

in mice, using four animals per dose level and four different doses. The LD50 was 269 

mg/Kg, using male mouse strain ddY by oral route and the observation period was 7 

days. 

Inhalation 

Pozzani et al ., (1959) investigated the mammalian toxicity of acetonitrile . Groups 

of 1-3 male dogs were exposed to 2000, 8000, 16000 and 32000 ppm acetonitrile 

during 4 hour. There were no deaths in either of the lower two groups (1 and 2 dogs 

exposed) . All those exposed in the upper two groups died (1 and 3 exposed) . 

Exposure for 8 hours (12 male and 12 female Nelson rats at 6 concentrations, 

32000,16000, 8000, 4000, 2000 and 1000 ppm) generated LC, values of 7551 ppm 

and 12435 ppm for males and females respectively . This apparent difference in 

sensitivity between males and females is not evident in the 4 hour tests (LCso 16000 

ppm) . Prostration and convulsive seizures often preceded death. Marked to moderate 

pulmonary haemorrhage and congestion was evident both in survivors and in those 

which died. A LC502828 ppm. was stableished for rabbit exposed to 3 concentration 

of acetonitrile during 4 hour; and LC50 5655 ppm was stableished for guinea pig, when 

groups of 6 (males and female) were exposed to 3 concentrations of acetonitrile during 

4 hour. 

Dogs appeared to be most resistant to the vapour. The rabbit and guinea pig 

are somewhat more sensitive . There was a greater difference in individual susceptibility 

to the vapour in rats than in the other three species tested . 

Willhite, (1981) exposed male CD-1 mice for 60 min . to concentrations of 

acetonitrile ranging from 500 to 5000 ppm and were maintained for the following 14 

d.The LCso value for acetonitrile was 2,693 ppm. Exposure to 5000 ppm killed all mice 

within 2 hours. Toxic effects included: intense dyspnea, gasping, tremors, convulsions 

and corneal opacity after 30-300 minutes. Gross autops, of mice which died showed 

only particularly red livers in some cases. 

Groups of 6 or 12 pregnant Syrian golden hamsters were exposed on day 8 of 

pregnancy to 1800, 3800, 5000, 8000 ppm acetonitrile during 1 hour (Willhite, 1983) . 

Sacrifice occurred on day 14. There were no overt signs of toxicity in those exposed 

to the lowest concentration. One of 6 animals died in the 3800 and 5000 ppm groups 

and 3 of 12 died in the highest concentration group . Overt effects included: Eye 

irritation, dyspnea, tremors, hypersalivation, ataxia, hypothermia, respiratory difficulty 

and coma. Histopathological examination of liver, kidneys and lung of affected animals 

-53- 
did not reveal any abnormalities. 

One female monkey exposed to 2510 ppm acetonitrile vapour, appeared normal 

after the first inhalation day (7 h) but, showed poor coordination followed by prostration 

and laboured breathing during the second inhalation day. Death occurred a few hours 

later. Engorgement of the dural capillaries and pleural effusion was found . Tissues 

were not examined microscopically because some autolysis occurred before autopsy 

(Pozzani et al ., 1959) . 

Dermal 

Acetonitrile has and LD50 by rabbit skin penetration of 1 .25 (0.84 to 1 .85) ml/Kg 

of the undiluted compound applied under polyethylene sheeting . It is of interest to note 

that the toxicity of acetonitrile by skin penetration is increased when application is 

made as a 75% (v/v) aqueous solution . 

The LD50 is 0.50 (0.37 to 0.67) ml/Kg of the 759'o aqueous solution (Pozzani, et 

al., 1959). 

Neat acetonitrile was applied in covered contact to the clipped skin apparently 

of 6 rabbits (Smyth and Carpenter, 1948) . Contact was maintained for 4 days, followed 

by observation for 10 days or until death (Smyth and Carpenter, 1944) . The LDso was 

given as 5ml/Kg; a density of 0.79 g/ml has been used . 

Other routes 

Female rats (Wistar or Nelson albino) were given acetonitrile undiluted by i .p. 

route . Two extreme LD50 values of 7.96 and 0.85 ml/Kg were found. A density value 

of 0.79 g/ml has been used to convert these to 6288 and 672 mg/Kg respectively . 

When diluted in saline the LD50 range was 3073-4440 mg/Kg. It is unclear why the 

range for neat acetonitrile should be so great (Pozzani et al ., 1959) . 

Different values for the LD50 by i .p . route on mice (NMRI-SPF or CD-1 strains) 

have been obtained by several authors using acetonitrile in water or saline : 175 mg/Kg 

(Willhite and Smith, 1981) ; 198 mg/Kg (Pozzani et al ., 1959); 400 mg/Kg( Zeller et al ., 

1969) and 521 mg/Kg (Yoshikawa 1968) . 

In the study of Willhite and Smith, five or six doses between 50-862 mg/Kg of 

acetonitrile in water, were administered i .p . to groups of nine or ten CD-1 male mice. 

The animals were observed for the following 7 days and the mean time to death was 

423 ± 503min. Intoxication syndrome was produced within 1 to 5 hr, included: intense 

dyspnea, gasping, ataxia, corneal opacity, hypothermia and convulsions. 

Cuny et al, 1932, reported a. LD50 of 3950 mg/Kg for acetonitrile when it was 

injected subcutaneously in to rats (cited in Pozzani et al ., 1959) . 

There is only a reference with respect to route of administration intravenous in 

the IUCLID (Pozzani et al ., 1959) . An unstated number of male or female Wistar or 

-54- 

sy 
albino rats, treated with neat acetonitrile, had LDso of 1 .68 ml/Kg (1327 mg/Kg using 

a density value of 0.79 g/ml for conversion) in both cases . 

4.1 .2.2.2 . Studies in humans 

4.1 .2.2.2 .1 . Inhalation 

In a human volunteer study, Pozzani et al ., (1959) studied the acute inhalation 

toxicity of acetonitrile in three men between the age of 31 and 47 inhaled 40 ppm for 

4 hours. 

Only the youngest subject experienced a slight tightness in the chest during the 

evening after inhalation and was a slight increase in the urinary thiocyanate levels . 

There was no detectable blood cyanide in any of the subjects . The two older subjects 

inhaled 80 ppm acetonitrile vapour for 4 h one week after the 40 ppm trial, with no 

symptoms. No blood cyanide was detected in any of the samples taken after the 

inhalation period . Nine days later, these two subjects inhaled 160 ppm for 4 hours. 

One subject reported a slight transitory flushing of the face 2h after inhalation, and a 

slight feeling of bronchial tightness about 5 h later. The blood cyanide and urinary 

thiocyanate levels of both subjects, did not change significantly. 

Some cases of severe intoxications for exposure to high concentrations of 

acetonitrile vapor have been reported: 

Grabois (1955) reported on 16 workers at a Chemical ~ plant accidentally 

poisoned with acetonitrile vapour during the brush painting of the inside walls of a 

storage tank. A comprehensive discussion of this incident has been given by Amdur 

(1959) . The paint contained 30-409'o acetonitrile and the thinner contained 90-95% 

acetonitrile . Because of the viscosity of the paint, the tank was heated to 25oC and 

thinned on the second day before application . Ventilation of the tank was stopped. 

One died after two days exposure, two were seriously ill and the remaining 13 

workers were also affected . Symptoms included weakness, nausea and vomiting . 

Convulsive seizure and coma were reported prior to death . Post-mortem examination 

revealed cerebral, thyroid, liver, splenic and renal congestion, and a "peach pit" odour 

of all tissues . The blood and urine cyanide concentrations were 7960 and 2150 

mg/litre, respectively . There was a trace of cyanide in the gastric fluid. Spleen, kidney 

and lung concentrations of cyanide were 3180, 2050 and 1280 mg/Kg tissue, 

respectively . No cyanide was detected in the liver. 

The worker who died had worked inside the tank for about 12 hours. Of the two 

other seriously affected workers, one had worked inside the tank near three hours and 

the other had spent 12 hours painting around the ports from the outside of the tank but 

inside the last hour. Two other men, less severely affected, had painted inside the tank 

for no more than 2.5 hours each on the 2nd day . 

Following the incident, the paint ingredients were not heated, adequate 

ventilation was provided and the concentration of organic cyanide was kept below 17 

ppm. There were no further incidents . 

Dequidt et al ., (1974) reported a heart failure and death occurred by acute 

-55- 
acetonitrile poisoning in a 19-year-old male photographic laboratory worker. After 

handling acetonitrile for 2 days, he poured an unknown amount of acetonitrile and 

boiling water on the floor to clean it . Four hours after work he complained of epigastric 

pain and nausea and vomited repeatedly. Next day he became comatose and had 

convulsions. Large amounts of cyanide, thiocyanate and acetonitrile were found in the 

blood and urine. He died 6 days after the poisoning. 

Dermal 

A case of paediatric accidental exposure to an acetonitrile-containing cosmetic 

were reported by Caravati & Litovitz (1988) . 

The exposure occurred both via the skin and by inhalation. Approximately 30 

ml of a nail remover containing 98-10096 acetonitrile spilled on a 2-year-old (12Kg) 

previously healthy boy and his bed (amount of contact to the skin was not specified) . 

No symptoms were noted immediately after the exposure. Eight hours later, the 

boy was moaning, poorly responsive, and had vomited . He became lethargic and pale . 

Whole-blood cyanide levels were: 6mg/litre 12 h after the exposure, 60-70 pmol/litre 

from 24 to 48 h and 15 Nmol/litre after 60 h. The patient was discharged 3 days later 

in good condition . 

Oral 

Caravati and Litoviz (1988) reported on a 16 month-old (11 .8 Kg) boy who 

ingested 15-30 ml of a nail remover (1-2g acetonitrile/Kg body weight) . The child 

vomited spontaneously about 20 min after the ingestion . About 12 h after the ingestion 

he was found dead . Postmortem examination showed moderately severe pulmonary 

oedema, a blood cyanide level of 119 mg/Kg and brain cyanide level of 0.2 mg/Kg. 

A case of acute acetonitrile intoxication in a 26-year-old man has been 

reported by Jaeger et al ., (1977) . The man ingested 40 g of acetonitrile in a suicide 

attempt. After a 3 h latent period, he suffered from vomiting, convulsions, coma, acute 

respiratory insufficiency, severe metabolic acidosis and two cardiac arrests. Recovery 

occurred over the following three months after treatment. 

A 22 year old female ingested an unspecified amount of acetonitrile and 

acetone. She died about 30 hours later. Postmortem examination revealed pulmonary 

oedema and haemorrhagic gastritis (Boggild et al ., 1990) . 

Turchen et al ., (1991) reported the case of 39 year old woman, who was found 

vomiting and confused 7 h after ingesting 59 ml of nail polish remover containing 99% 

acetonitrile . After 12 h ingestion, she developed severe metabolic acidosis, seizures 

and shallow respiration . Eight hours after ingestion she had a whole blood cyanide 

level of 3130 Ng/litre . At 65 h the serum cyanide level was 10 mg/I and thiocyanate 120 

-56- 
_~ C'r- /,Ot4 ;Vti~ (~ 10A's- P_ 

. 

mg/I, whereas at 77 h were 12 mg/I and 30 mg/I, respectively . She responded to the 

treatment with sodium nitrile and sodium thiosulphate . On the fifth hospital day the 

cyanide level was 360 pg/I. and thiocyanate level 30 mg/I. The patient was discharged 

on day six. 

A case of acute acetonitrile poisoning of a 3-year-old (17.2 Kg) child was 

reported by Geller et al ., (1991) . The child ingested 15-30 ml of a nail tip and glue 

remover containing acetonitrile . The amount of acetonitrile ingested was estimated to 

be 0.8-1 .7 g/Kg. Gastric lavage was performed . Three hours and 45 min . after 

ingestion, the cyanide blood level was 1 .24 mg/l and thiocyanate 11 mg/I. Thirteen 

hours after the ingestion the child vomited, was confused and developed seizures. The 

child was treated and discharged from hospital 42 h after the ingestion. 

Kurt et al, (1991) reported a case of a 15.8 Kg 2-year-old girl who ingested 5-

10 ml (0.25-0.5 g/Kg) of a nail glue containing 84% acetonitrile. The following morning 

she was moaning, restless and vomiting. Toxic clonic seizures also appeared about 

14h after ingestion, and became comatose with hyperpnoea and tachycardia and with 

marked hypoxia and acidosis. She was treated and discharged from hospital after 2 

days. 

Vomiting occurred within 6 hours of a 23 month-old child ingesting 60 ml of a 

product containing at least 98% acetonitrile . He became unresponsive 24h after the 

ingestion. He was treated and discharged from hospital on the third day (Losek et al ., 

1991) . . . - , 

Michaelis et al ., (1991) reported a case of suicidal oral acetonitrile ingestion in 

a previously healthy 30-year-old- man. He ingested --about-5 mi.-(64 mg/Kg). of 

acetonitrile (98 %) and, 30 min, -later, about 1 ml of ammonium:,and. vomited once. :. 

Gastric lavage was performed 5.5 h after ingestion. Peak serum acetonitrile and blood 

cyanide levels were 99 .2 and 15 .0 mg/I . Half-lives were calculated for acetonitrile and 

cyanide and found to be 32 and 15h, respectively . 

Two fatal cases of a couple who ingested acetonitrile by mistake was reported 

by Jones et al ., (1992). They were found dead with traces of vomit. Acetonitrile levels 

were 0.8 g/I in blood, 1 .0 g/I in urine and 1 .3 g/I in stomach contents. Blood inorganic 

cyanide levels were 4.5 mg/I (male) and 2.4 mg/I (female) . 

4.1 .2.2 .3. In vitro studies 

Knox et al ., (1986) studied cytotoxicity of acetonitrile in BCL-DL cells. The 

method used was dybinding and the harvest time 72 h, the results were IC20>24 mM, 

IC50>24mM and ICso>24mM. 

Clothier and Hulme (1987) using Mouse 3T3-4 cells, FRAME Kenacid blue 

method and harvest time after 72 h obtained IC50 = 562 mM Dierichx (1989) obtained 

IC50 = 494 mM using human hepatoma Hep G2, 24 h harvest time and cellular 

-57- 

62 
protection content as method. In like manner, the IC50 values in mouse neuroblastome 

cells and in rat glioma cells, were 17.8 and > 20 mM, respectively . 

4.1 .2 .2 .4. Summary of single exposure studies 

Different animal species and individuals of the same species varied widely in 

susceptibility to acetonitrile in single-dose toxicity studies by various routes . 

The range of LDso values acetonitrile in mammals is between 165 and 6762 

mg/Kg body weight. Mouse and Guinea-pig seem to be the most sensitive species. 

These studies were performed without GLP information. 

A study showed that acetonitrile was more toxic to immature rats (14-day-old) 

than to older rats given oral doses of 160-3500 mg/Kg. Other study reported that using 

male or female wstar or Nelson albino rats, the males where more susceptible than 

the females; 8.53 ml/Kg for females and 1 .68 ml/Kg for males, the route was by 

gavage. 

The main symptoms in animals appear to be prostration followed by seizures 

and convulsions. 

Acetonitrile has rabbit dermal LDsa of 1 .25 ml/Kg . It is of interest to note that the 

toxicity by skin penetration is increased when application is made as a aqueous 

solution . Dermal application of acetonitrile causes systemic toxicity . 

The 8h inhalation LCSo in male rats is 7500 ppm (13,740 Mg/M3) . Rabbits and 

mice were more sensitives than rats, with LC50 of 2828 ppm and 2693 ppm, 

respectively and time of exposures of 4 hour for rabbits and 60 min for mice. A 4-hour 

exposure of dogs at concentrations up to and including 8000 ppm produced no deaths, 

but deaths did occur at concentrations of 16,000 and 32,000 ppm. Gross pathology 

indicated pulmonary haemorrhage and vascular congestion . 

Animals exposed to acetonitrile via different routes of dosing always showed 

respiratory symptoms: rapid and irregular respiration, laboured or difficult breathing and 

intense dyspnea. 

The determination of blood cyanide and urinary thiocyanate should not be relied 

upon as evidence of brief inhalation to low concentrations of acetonitrile vapour. No 

blood cyanide was found in human subjects inhaling 40, 80 and 160 ppm vapour, and 

there was no correlation between thiocyanate excretion and acetonitrile concentration. 

The variability of subjective responses of humans to 40, 80 and 160 ppm 

acetonitrile vapour suggests that, even if a concentration of the solvent vapour were 

selected that would not endanger the health of the majority of workers, it might cause 

discomfort to some. 

Symptoms and signs of acute acetonitrile intoxication include chest pain, 

-58- 
tightness in the chest, nausea, emesis, tachycardia, hypotension, short and shallow 

respiration, headache, and seizures . The systemic effects appear to be largely 

attributable to the conversion of acetonitrile to cyanide . Blood cyanide and thiocyanate 

levels are elevated during acute intoxication . Two deaths after exposure to acetonitrile 

vapour in the workplace and one fatal case of a child ingesting and acetonitrile 

containing cosmetic have been reported . Elevated tissue cyanide concentrations were 

found in postmortem examination of these cases. 

In vitro studies acetonitrile was weekly cytotoxic in a range of cultured cells. The 

concentration which reduced cellular protein by 50% were about 0.7-23 g/I . 

In the Annex I of Directive 67/548/EEC, acetonitrile is classified as Toxic (T) ; Rphrases 23/24/25: Toxic by inhalation, in contact with skin and if swallowed . 

4.1 .2.3. Irritation 

4.1 .2.3.1 . Studies In animals 

Skin 

Data sheet IUCLID includes two studies about skin irritation . In one study a 

cotton pad (2.5 cm x 2.5 cm) saturated with acetonitrile is placed on the skin of white 

rabbits for 15 minutes or 20 hours. 

After the 15 minutes application the treated area was first washed with undiluted 

polyethyleneglycol 400 and finally washed with 50 % aqueous polyethyleneglycol 400, 

after 20 hour treatment however, the skin was not washed. 

The reaction was observed after 1,3 and 8 days as well as after removed of the 

pad. No reaction was seen at any time, after either exposure period (Zeller H. et al ., 

1969) . 

Smyth and Carpenter (1948) describe the skin irritancy of acetonitrile as similar 

to that of acetone. The method used in the determination is apparently that of Smyth 

and Carpenter 1944, in which 0.01 ml of the neat material was applied to the clipped 

belly of an albino rabbit . Observations were made after 24 hours . In one standard test 

(Clayton and Clayton, 1982) acetone is described as slightly irritant to the skin. 

Eye 

In studies in 5 rabbits, 1 drop of neat acetonitrile was instilled into the eye . After 

24 hours the effects were graded as 5 on a scale 1-10 (Smyth and Carpenter, 1948) . 

The same authors (1944, 1946) giving details of the test and of data interpretation . The 

1946 paper states that a score of >_5 represents severe injury . Zeller, et al ., (1969) 

tested the acetonitrile, one drop of neat acetonitrile was applied to the conjunctival sac 

of the rabbit's eye . The reaction was noted after 10 minutes, 1 and 24 hour, 3 and 8 

days. An irritation of score of 3, out of a possible maximum of 6; strong vascular 

injection with edema or slight necrosis, was recorded. 

-59- 

6y 
Pregnant hamsters exposed to 1800, 3800, 5000 and 8000 ppm acetonitrile via 

inhalation for 60 min. caused irritation to the eyes and nose in 4 of 12 in the top 

concentration group and irritation (without to specify) to all exposed to 5000 . (Willhite, 

1983) . Corneal opacity has been observed after either inhalation or intraperitoneal 

administration of acetonitrile in male mice (Willhite, 1981 ; Willhite and Smith 1981) . 

4.1 .2.3.2. Studies in humans 

Humans accidentally inhaling 500 ppm for brief periods, reported some irritation 

of nose and throat (IPCS 1993) . 

4.1 .2.3.3. Summary of irritation 

The information from studies in animals indicate that acetonitrile is slightly irritant 

to the skin and one drop of neat acetonitrile applied to the conjunctival see produced 

strong vascular injection with edema or slight necrosis. When the exposition is via 

inhalation, acetonitrile cause irritation to the eyes and nose in concentrations of 8000 

ppm . 

Although these studies were performed without GLP information and without 

according to OCDE guidelines, all available data indicates that liquid acetonitrile is a 

eye irritant and the risk phrase R36 (Irritating to eyes) should be included in the 

proposal of classification . 

4.1 .2 .4. Corrosivity 

The studies in animals and humans in 4.1 .2.3 . indicate that acetonitrile is not 

corrosive to the skin or eyes. 

4.1 .2.5. Sensitization 

No data is available on sensitization of acetonitrile in experimental animals. 

4.1 .2.6. Repeated dose toxicity 

4.1 .2.6.1 . Studies in animals 

Inhalation 

Studies in rat 

The National Toxicology Program (1994), has well conducted a subchronic 

inhalation study, according to OCDE guideline No 413, on rats exposed to acetonitrile 

for 13 weeks. 

Groups of 10 male and 10 female F344/N rats were exposed to 0, 100, 200, 

-60- 

65 
400, 800 or 1600 ppm (equivalent to 0, 168, 335, 670, 1,340 or 2,681 mg/m3) 

acetonitrile by inhalation for 6 hours per day, 5 days per week for 13 weeks. Animals 

were approximately 6 weeks old on the first day of exposure. 

Six male and three female rats exposed to concentrations of 1,600 ppm and one 

male exposed to 800 ppm died during the study; all but one of these deaths occurred 

during the first 2 weeks of the study. At exposure concentrations up to and including 

800 ppm, the final mean body weights and body weight gains were generally similar 

to controls. At the 1600 ppm concentration, body weight gains were lower than 

controls ; the final mean body weights were 81 % of the control value in males and 91 % 

of the control value in females . Hypoactivity and ruffled fur were observed in 800 ppm 

males and 1,600 ppm males and females during the first week of the study. Additional 

clinical findings in 1,600 ppm males that died during week 1 were ataxia, abnormal 

posture, and clonic convulsions. 

An anaemia evidenced by decreases in red blood cell count, haemoglobin 

concentration, and haematocrit, occurred in the 1,600 ppm males and females and in 

800 ppm female rats . The anaemia was characterized as nonresponsive, normocytic, 

and normochromic because the reticulocyte counts, mean erythrocyte volume, and 

mean erythrocyte haemoglobin concentrations in these groups were similar to control 

values. In the 1,600 ppm female rats, decreases in triiodothyronine (T3) concentration 

occurred in the absence of alterations in thyroxine (T4) and thyroidstimulating hormone 

(TSH) concentrations. 

Minor, sporadic changes in other parameters were considered unrelated to 

treatment . 

Gross and histopathologic changes were restricted to the 800 ppm male and 

1,600 ppm male and female rats that died during the study; these included lung lesions 

consisting of congestion, edema, and haemorrhage in alveoli . 

A spectrum of lesions that included brain haemorrhage ; cellular depletion of the 

bone marrow; thymic atrophy; lymphoid depletion of the spleen (females) and depletion 

of corpora lutea in the ovary were typically noted primarily in animals dying early. 

In this study a NOAEL: 400 ppm and a LOAEL: 800 ppm were established . 

In a 92-day unpublished study, reported as an abstract, acetonitrile was 

administered by inhalation to Fischer-344 rats at concentrations of 0, 25, 50, 100, 200 

and 400 ppm., 6 hours/day, 5 days/weed. All groups were composed of 10 animals of 

each sex. One male in the 400 ppm group died during the study . There was slight 

cytoplasmic vacuolization of hepatocytes in females at 400 ppm. Marginal decreases 

in mean leucocyte counts were reported in males at 100 and 200 ppm and in both 

males and females at 400 ppm (Coate W.B ., 1983) . 

In a published study of Pozzani et al ., 1959a, rats Wistar were exposed to 0, 

166, 330, and 655 ppm acetonitrile vapour, 7h/day, 5 days/week, for a total of 90 days. 

All groups were composed of 15 animals of each sex, however, there were two sets 

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of controls groups (60 animals in all) . The body weight gains and the organ weights 

did not differ significantly from the controls. 

Furthermore, the few deaths that did occur were attributable to extraneous 

infection, and their incidence was unrelated to concentration. 

The tissues of the rats that survived the inhalation of acetonitrile for 90 days 

were examined microscopically. Of the 28 rats inhaling 166 ppm vapour, 1 had 

histiocyte clumps in the alveoli, and another had atelectasis. Only three cases of tissue 

abnormality were observed in the 26 rats inhaling 330 ppm of the vapour. These 

involved lung changes such as bronchitis, pneumonia, atelectasis, and histiocyte 

clumps in the alveoli . A small lung granuloma was found in 1 of the 29 rats which 

served as controls for these two inhalation levels . After the inhalation of 655 ppm 

acetonitrile vapour, 10 out of 27 animals showed alveolar capillary congestion and/or 

focal oedema in the lug, often accompanied by bronchial inflammation, desquamation 

and hypersecretion. Tubular cloudy swelling of the kidneys in eight rats and swelling 

( of the livers of seven rats were observed . 

Statistical analysis showed that these lung, kidney and liver effects occurred to 

a significantly greater degree than in the control animals with P-values of 0.001, 0.005 

and 0.04 respectively . No lesions were found in the adrenals, pancreate, spleens, 

testes and tracheas examined. Focal cerebral haemorrhage was observed in one of 

the five brains examined. The significance of the effects in the lower groups is unclear. 

Some thiocyanate was excreted by the rats inhaling 330 and 166 ppm 

acetonitrile vapour, although the amount of thiocyanate excreted was not proportional 

to the concentration of acetonitrile inhaled . The urinary thiocyanate apparently was not 

excreted entirely during the 17-hour rest period between inhalation periods but was 

virtually all excreted during the 2.5 day rest period over the week end.The haematocrit 

and haemoglobin values of the five female rats inhaling 655 ppm acetonitrile did not 

differ significantly from the controls. 

A NOAEL: <166 ppm and a LOAEL: 166 ppm were established. 

Roloff et al ., (1985, abstract) exposed groups of male and female rats (strain 

unspecificied) to acetonitrile vapour: 0, 618, 1847, 6239 ppm (0, 1038, 3104, 10485 

mg/m3) for 1 month (6h/day, 5 days/week) . A citation of this summary states that more 

of 40 tissues were examined per animal (Johannsen and Levinskas, 1986) . A full 

report of this study has apparently not yet been published . Death and reduced body 

weight gains were observed at the highest exposure level. Respiratory and/or ocular 

irritation were noted in animals exposed to 1847 and 6239 ppm. Mild anaemia was 

seen in animals exposed to acetonitrile ; it is not clear at which concentration . A 

NOAEL of 618 ppm was established . 

Studies in mice 

The National Toxicology Program (1994), has well conducted a subchronic 

inhalation study, according to OECD Guideline No 413, on mice exposed to acetonitrile 

for 13 weeks.Ten mice (B6C3F1) of each sex were exposed to acetonitrile vapour at 

0, 100, 200, 400, 800 and 1600 ppm, 6h/day, 5 days/week . All groups were composed 

of 10 mice of each sex. 

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All male and female mice in the 1,600 ppm groups died by week 3 of the study. 

Six additional animals, one female receiving 400 ppm and one male and four females 

receiving 800 ppm also died before the end of the study. The final mean body weights 

and body weight gains of all female exposure groups that survived were similar to 

controls. The final mean body weight of all exposed male groups were slightly lower 

than that of the controls . Hypoactivity and a hunched, rigid posture were observed in 

800 and 1,600 ppm mice during the first week of the study. 

Absolute liver weights were significantly greater than those of the controls in 

males exposed to concentrations of 200 ppm and above and in 800 ppm females; 

relative liver weights were significantly, greater in all exposed male groups and in 

females exposed to 400 ppm or higher. 

Microscopic lesions were observed in the forestomach, liver, and adrenal gland. 

Grossly, focal or multifocal pale, dark brown or black lesions were consistently 

observed in the mucosa of the anterior forestomach of male and female mice exposed 

to concentrations of 200 ppm (7), 400 ppm (8), 800 ppm (8) and 1600 ppm (5), in 

females and in males the incidence was 400 ppm (5), 800 ppm (6) and 1600 ppm (1) . 

Microscopically, these lesions corresponded to focal or multifocal squamous 

epithelial hyperplasia . The average severity of these lesions was similar between 

exposure groups, with the exception of female mice exposed to 200 ppm in which the 

lesions were less prominent. 

Focal ulcers associated with areas of epithelial hyperplasia occurred in one 

female exposed to 200 ppm and one male and five females exposed to 1600 ppm. A 

high incidence of hepatocellular cytoplasmic vacuolation occurred in the male and 

female mice exposed to 400 ppm and 800 ppm. Vacuolation appeared to be a slight 

distension of preexisting cytoplasmic clear spaces and is considered to represent 

increased glycogen storage. The absence of such changes in hepatocytes of 1,600 

ppm mice that died may be indicative of increased utilization of hepatocyte glycogen 

stores . 

Additional alterations that occurred only in mice that died during the study, 

including lymphoid depletion and lymphocytolysis in the thymus, spleen, and bone 

marrow, and pulmonary congestion, were considered to be nonspecific changes 

typically observed in moribund animals. 

In this study a NOEL females: 100 ppm and 200 ppm for males were 

established. 

An unpublished study, acetonitrile was administered by inhalation to B6C3F1 

mice at concentration of 0, 25, 50, 100, 200 and 400 ppm during 92-day (Coate, 

W.B.,1983) . All group were composed of 10 animals of each sex. One male in each 

of the 50, 200 and 400 ppm groups died. There was an increase in body weight gain 

in all males exposed to 50, 100, 200 and 400 ppm, and in females of the 200 and 400 

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ppm groups ; body weight gain was decreased by comparison with controls in the 25, 

50 and 100 ppm female groups. 

The statistically significant effects in the mice included decreased blood urea 

nitrogen levels, red blood cell cholinesterase counts and haematocrits in females 

exposed to 200 or 400 ppm of acetonitrile . Hepatic vacuolization and hypertrophy were 

observed at all dose levels evaluated including controls, but the intensity of the hepatic 

lesions appeared greater in male and female mice exposed to 200 or 400 ppm of 

acetonitrile . Elevated relative liver weights were observed in males at 400 ppm and in 

females at 100 and 200 ppm. A dose related decrease in leucocyte count and serum 

Ig G levels occurred, but did not appear to indicate specific T- or B- lymphocyte 

dysfunction, and the biological significance of these findings is unclear. 

A NOAEL 100 ppm and LOAEL 200 ppm were established . 

Immuquest Labs-Inc. (1984) exposed groups of unspecified numbers of female 

B6C3F1 mice to acetonitrile at 0, 100, 200 or 400 ppm, 6 hours/day, 5 days/week for 

90 days. There were no effects on physical appearance, body weights or gross 

appearance at necropsy. Mice in the 200 and 400 ppm groups had atrophy of thymus, 

which was noted upon histopathological examination. Slight vacuolization of 

hepatocytes accompanied by hydropic degeneration was also observed at 400 ppm. 

There were no treatment-related effects on selected clinical 'chemistries, but mice at 

200 and 400 ppm had dose-related decreases in haematoc~its, blood haemoglobin 

concentration, erythrocyte and leucocyte counts. Changes in haematological 

parameters were not significant at 100 ppm. 

No significant effects on organ weights were observed, but the investigations 

noted a trend toward depressed thymus weights at 200 and 400 ppm . 

After 14 days, Immuquest Labs, evaluated immune function in mice exposed by 

the same protocol . A significant dose-related depression of serum concentration of Ig 

G was observed in all exposed mice, but no effects were observed on the Cunningham 

plaque-forming response to sheep erythrocytes, the lymphocyte blastogenesis test, 

delayed hypersensitivity response or susceptibility to challenge with PyB6 tumor cells. 

Study in dog and monkeys 

Three male dogs inhaled 350 ppm acetonitrile (7h/day, 5 days/week) for 91 days 

(Pozzani, et al ., 1959) . A statistically significant drop in the mean body weight was 

observed on the third and fifth inhalation days. The haematocrit and haemoglobin 

values of the three dogs were depressed the fifth week of inhalation, but with the 

exception of one dog. There was a return to preinhalation values toward the end of the 

91-day inhalation period .The depressions in the those values were not accompanied 

by any significant deviation in the erythrocyte counts. No significant gross pathologic 

change was seen in the dogs. Histological examination of the tissues revealed some 

focal emphysema and proliferation of alveolar septa LOAEL: 350 ppm. 

Two studies have been carry out with Rhesus monkeys. In an inhalation study 

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99 days (7 h/day, 5 days/week) four Rhesus monkeys: one female was exposed to 

2510 ppm, two females to 660 ppm and one male to 330 ppm (Pozzani, et al, 1959) . 

None of the four monkeys experienced an appreciable weight loss during their 

respective inhalation periods. The monkey at the highest concentration 2,510 ppm, 

appeared normal after the first inhalation day but showed poor coordination followed 

by prostration and laboured breathing during the second inhalation day. Death 

occurred a few hours later. 

In the two monkeys exposed to 600 ppm there was also incoordination from the 

second week. One monkey died on day 23 and the other on day 51 .The monkey which 

inhaled 330 ppm exhibited overextension reflexes and considerable excitability toward 

the end of its 99-day inhalation period and was sacrificed then. These three animals 

on gross examination showed focal dural or subdural haemorrhage in the parietal 

and/or occipital tissues immediately adjacent to the superior sagittal sinus. 

Engorgement of the dural capillaries and pleural effusion were found in the female 

which died at the 2,510 ppm level. Tissues from Monkey, which inhaled 2,510 ppm, 

were not examined microscopically because some autolysis occurred before autopsy. 

Examination of the tissues from monkeys which inhaled 660 ppm, revealed focal areas 

of emphysema and atelectasis with occasional proliferation of alveolar septa. Focal 

cloudy swelling of the proximal and convoluted tubules of the kidneys was seen. The 

cause of death was not explained by the lesions observed in the tissues examined 

microscopically. The monkey, which inhaled 330 ppm vapours, had chronic 

pneumonitis as evidenced by diffuse proliferation of alveolar septa, monocytic 

infiltration, and pleural adhesions.The cause of death of the other two was not 

explained by the lesions observed in the tissues examined microscopically 

In another inhalation study (Pozzani, et al, 1959) three male Rhesus monkeys 

were exposed to 350 ppm acetonitrile (7 h/day, 5 days/week) for 91 days, and at the 

end of the study the animals were sacrificed . At autopsy, slight to moderate 

haemorrhage of the superior and inferior sagittal sinuses were found in the brains of 

all three monkeys. Small discrete caseous nodules were seen in the lungs of two 

monkeys, as well as a pale liver in one of these two. Microscopic examination of 

tissues showed focal emphysema and diffuse proliferation of alveolar septa. Acute 

bronchitis was observed in one animal, and lung tissues from all three monkeys 

invariably contained focal accumulations of pigment-bearing macrophages . 

Cloudy swelling of the convoluted kidney tubules, primarily proximal, was noted 

in two of the three monkeys . NOAEL < 330 ppm, LOAEL = 330 ppm . 

Oral 

Data regarding repeated dose toxicity of acetonitrile could not be located in the 

available literature . In the absence of oral data, inhalation data may be utilized . The 

available inhalation studies have been reviewed above. In this studies, mice appear 

to be more sensitive than rats to the effects of acetonitrile . Although monkeys and 

dogs may be more sensitive than mice, these species were only examined in 

preliminary evaluations utilizing few animals at a single exposure level. Considering all 

of the evidence. The NOAEL established to mice in a well- conducted 13-week 

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inhalation study was 100 ppm . 

The mg/Kg/day dose was calculated as follows: 

168 mg/m3 (100 ppm) x 0.039 M3 /24h (mouse ventilatory volume, U.S.E.P.A. 

1980) x 6h/24h x 5 days/7 days: 0.03 Kg = 39 mg/Kg/day. 

An absorption efficiency of 50% is utilized to estimate an oral NOAEL resulting 

in an equivalent oral estimate of 19.5 mg/Kg/day. 

Other routes 

Two studies are included in data sheet IUCLID about subcutaneous 

administration . Two species, rat and rabbits were tested during 28 days, rats were 

exposed to 0.02, 0.04, 0.08 ml/animal and rabbits of 4-month-old daily subcutaneous 

injections of 0.1 ml acetonitrile . Two groups of four male rabbits developed pronounced 

(more than twice normal size) thyroid hyperplasia whereas one group of four females 

showed no effect . (Marine et al ., 1932a) . A further study (Marine et al ., 1932b) 

suggested that young rabbits were more susceptible than adults and that the effect 

varied with the strain . 

4.1 .2.6.2. Studies In humans 

No data are available in humans. 

4.1 .2 .6.3. Summary of repeated exposure studies 

There is no information available on the effects of repeated exposure to 

acetonitrile in humans. 

Clinical findings observed on rats and mice exposed to acetonitrile for 13 weeks 

were hypoactivity and ruffled fur during the first week at highest concentrations (800 

and 1600 ppm) . Females rats exposed to 1600 ppm had significantly greater absolute 

and relative heart, kidney and liver weights than those of the controls . In mice this 

findings appears at 200 ppm. In rats clinical pathology findings included anaemia, 

evidenced by decreases in red blood cell count, haemoglobin concentration and 

haematocrit and lesions consisting of congestion, edema and haemorrhage in alveoli 

at highest concentrations (800 and 1600 ppm) . Therefore the NOAEL in mice is 100 

ppm and the NOAEL in rats is 400 ppm. This is consistent with the results of other 

subchronic inhalation studies. 

In other study was observed a depressed haematocrit, haemoglobin, red blood 

cells and white blood cells in mice exposed 6.5 h/day, 5 days/week, for 13 weeks at 

200 and 400 ppm. Female rats exposed at 400 ppm had slightly more pronounced 

cytoplasmic vacuolization of the hepatocytes . 

Dogs and monkeys exposed exposed 7 h/day, 3 days/week for 91 days at a 

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7I 
mean acetonitrile vapour concentration of 350 ppm showed minor variations in body 

weight, haematocrit, and haemoglobin. Both, monkeys and dogs had pulmonary 

abnormalities. 

Autopsy of monkeys noted cerebral haemorrhage and cloudy swelling of the 

kidney tubules was noted in two of the three exposed monkeys. 

In summary monkeys were more sensitive than dogs to the same dose of 

inhaled acetonitrile (350 ppm) . 

The NOAEL established to rat was 400 ppm and to mice 100-200 ppm. in a 

well-conducted 13-week inhalation study, according to OECD Guideline No 413. 

An oral NOAEL of 19.5 mg/Kg/day is the result from inhalation exposure of mice 

to 100 ppm, 6 hours/day, 5 days/week. 

4.1 .2.7. Mutagenicity 

4.1 .2.7.1 . In vitro studies 

Several test methods for investigating the mutagenicity and genotoxicity of 

acetonitrile are available in vitro. 

Bacterial studies 

Florin et al ., (1980) in a screening of tobacco smoke constituents for 

mutagenicity using the Ames test, acetonitrile was assayed qualitatively using strains 

TA98, TA100, TA1535 and TA1537 with and without S-9 from aroclor-induced rats, 

at 3 l.cmol/plate and the results were negative. 

Schlegelmilch et al ., (1988) tested acetonitrile in the Ames test 

(Salmonella/microsome assay) performed with strains TA98 and TA100. The 

compound was tested with and without metabolic activation, using S9 preparations 

from phenobarbitone-pretreated and autoinduced rats. Autoinduction was performed 

by chronic (7days) application of a dose equivalent to a 5 % oral LD5o value of 

acetonitrile . 

The concentrations used were 0.27, 1 .35, 2.71, 13 .6, 27 .1, 136, 271 y 1350 mM 

with both strains in triplicate plates . Acetonitrile not found to be mutagenic in the 

Ames/Salmonella assay with or without metabolic activation . The concentration 1350 

mM results to be toxic with strain TA98 in the presence of S9-mix (phenobarbitone) . 

Mortelmans et al ., (1986) tested acetonitrile in the Salmonella preincubation 

assay, strains TA1535, TA1537, TA97, TA98 and TA100 within a dose range up to 10 

mg/plate and in the presence and absence of the metabolic activation systems 

prepared from Sprague-Dawley rats or Syriam hamster liver pretreated with Aroclor 

1254 . 

This study employed a 20 minute preincubation period at 37oC . 

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All tests were repeated using either the same or different S9 concentrations 

(10% and 30%) . Each trial consisted of triplicate plates of concurrent positive and 

negative controls and five doses of acetonitrile 100, 333, 1000, 3333 and 10,000 

Mg/plate. 

In the absence of toxicity 10,000 pg/plate was selected as the high dose. All 

assays were repeated . 

The test was performed in two different laboratories . Under the conditions of the 

study, acetonitrile did not cause a positive response, with or without metabolic 

activation, in any of the tested strains . 

Yeast studies 

Acetonitrile was tested for their genotoxic potential in an assay using 

Saccharomyces cerevisiae (strain D7), with and without metabolic activation (S9 

preparations from phenobarbitone-pretreated and autoinduced rats) . Ten concentration 

were used: 360, 405, 450, 495, 540, 585, 630, 675, 720 and 768 mM) in triplicate 

plates . No reversion from isoleucin auxotrophy to prototrophy exceeding the 

spontaneous rate could be detected in strain D7 after various doses of acetonitrile . 

There was no effect on mutation rate by the presence of a metabolic activation system. 

A weak recombinogenic effect was detectable, when phenobarbitone-induced 

S9 was added to the incubation mixtures, the number of trp` convertants on selective 

plates increased up to twice the spontaneous number although the corresponding 

doses were very high (675 and 720mM) . 

No convertogenic effect could be demonstrated when autoinduced S9 or no 

metabolic activation system were added to the incubation mixtures (Schlegelmilch, et 

al ., 1988). 

Acetonitrile induced chromosome loss Saccharomyces cerevisae strain D61 M, 

with or without a cold interruption phase and in the absence of metabolic activation 

(Whittaker et al ., 1989) . The study was carried out in two laboratories with similar 

results. The following additions are made to 2ml of D61 M culture: 1, 3, 5, 10, 20, 30, 

50, 75 and 100 NI, to yield final concentrations of 0.05-4 .76% (v/v) respectively . 

Positive and negative controls are also included. Cultures are incubated according of 

the two following protocols: 

1) Standard 16 h incubation at 30oC (tubes are shaken at 300rpm at a 45o angle) . 

2) Cold interruption (tubes are incubated at 30oC for 4h, transferred to an 

ice/water bath for 16h, vortex mixed, warmed for 2 min . in a 30oC water bath 

and further incubated at 30o C for 4h) . 

Zimmerman et al ., 1985, obtained similar results using 2.91% and 4.76% 

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acetonitrile . All treatment were started by pipetting the acetonitrile into a growing cell 

culture at a titer between 3 and 10 million cells per ml 4h of incubation at 28oC were 

followed by a storage of about 17h in ice. Cells were plated aftet 4-5h of additional 

incubation at 28oC. Acetonitrile strongly induced aneuploid but not recombination or 

point mutation. 

Groschel-Stewart et al ., 1985 demonstrated that the aneuploid-inducing activity 

of aprotic polar compounds in yeast is associated with their ability to block assembly 

in vitro of porcine brain tubulin . In the case of acetonitrile, this block could be achieved 

at concentrations much lower than those necessary to induce aneuploid in yeast. 

Mammalian cells studies 

A well-conducted gene mutation assay (HGPRT locus) in cultured Chinese 

hamster ovary (CHO) cells, was carried out by Bioassay Systems Corporation (1984) . 

This assay was conducted both in the absence and presence of Aroclor-1254-induced 

rat liver metabolic activation. 

The optimal dose levels for the mutation assay were selected following a 

preliminary toxicity test based on colony forming efficiency. Approximately 40% of the 

cells survived 15 .4 mg/ml while less than 0.03% survived at 77.1 mg/ml. 

Based on those results concentrations ranging from 0.1 to 30 mg/ml were 

selected for the first nonactivated mutagenesis assays and eight concentrations 

ranging from 1-25 mg/ml were tested in the second nonactivated mutagenesis assay. 

The exposure time was 16 hours. When the assay was carried out in the presence of 

0.424 mg/ml of S9, CHO cells were exposed during 4 hours at 37oC to solvent ranging 

from 4-16 mg/ml in the first experiment and eight concentration ranging from 8-20 

mg/ml in experiment No. 2. 

No significant differences (cr=0 .05) between the mutation frequencies of 

acetonitrile and the negative control were found both in the absence and presence of 

S9 . 

Other gene mutation assay was carried out, in this case with L5178Y mouse 

lymphoma cells and in the presence and absence of metabolic activation system . 

Acetonitrile was neither mutagenic nor toxic at the maximum tested dose (5mg/ml) 

(brief abstract Rudd et al ., 1983) . 

Acetonitrile, was tested in the Chromosome Aberrations test and Sister 

Chromatid Exchanges test, using chinese hamster ovary cells (Galloway, et al ., 1987) . 

Acetonitrile was tested both in the presence and absence of Aroclor 1254-

induced male Sprague-Dawley rat liver S9 and cofactor mix. 

Each test consisted of concurrent solvent and positive controls and of at least 

three doses of acetonitrile . In the absence of toxicity, 5000 /jg/ml was selected as the 

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high dose. 

A single flask per dose was used, and tests yielding equivocal or positive results 

were repeated . 

In the Chromosomal Aberrations test, without S9, cells were incubated with 

acetonitrile for 12 hours; in the presence of S9, cells were treated with acetonitrile for 

2 hour, after which the treatment medium was removed and the cells were incubated 

12 hours in fresh medium. The concentrations tested were 500, 1600 and 5000 Ng/ml 

both with and without S9. One hundred first-division metaphase cells were scored at 

each dose level. Result obtained showed a slight increases in the incidence of 

chromosome aberrations at 5000 Ng/ml (P<0.05) in the presence of S9 but no 

induction of aberrations occurred in the absence of S9. 

In the SCE test without S9, CHO cells were incubated for 26 hours with 

acetonitrile at 160, 500, 1600 and 5000 pg/ml doses. Bromodeoxyuridine (BrdU) was 

added 2h after culture initiation . In the SCE test with S9 cells were incubated with 

acetonitrile (500, 1600 and 5000 Ng/ml) and S9 for 2h . The medium was then removed 

and replaced with medium containing BrdU and incubation proceeded for an additional 

26 hours. Fifty second-division metaphase cells were scored for frequency of 

SCEs/cell from each dose level. Acetonitrile produced a positive response without S9 

at 5000 pg/ml (P<0.01) ; with S9, no increase in SCE was noted . 

4.1 .2.7.2. In vfvo studies 

Fix and Zeste genetic test systems employing female Drosophila melanogaster 

were performed by Osgood et al ., (1991 .a,b) . Acetonitrile was found to induce 

chromosome loss as well as chromosome gain in both assays . 

Acetonitrile was administered by feeding to either early third instar larvae (LF3), 

late third instar (LF4) in one experiment, or to young adult (AF) females. The 

concentrations tested were 2000, 5000, 20000 and 50000 ppm, the solvent system 

used was water. 

With Fix acetonitrile was strongly positive only after feeding to third instar larvae 

(LF3) . 

With Zeste the chemical induced aneuploid after adult feeding (AF) with no 

discernable effect after LF3. Zeste larvae were substantially more sensitive to 

acetonitrile with 78% mortality at 20000 ppm compared to 30% for FIX larvae . The 

magnitude of effect, the increment relative to the concui sent control was approximately 

2 fold for FIX and 5 fold for Zeste . (Osgood et al ., 1991 a) . 

The Drosophila ZESTE system was used to monitor the induction of sex 

chromosome aneuploid following inhalation exposure of adult females to acetonitrile . 

Acetonitrile was a highly effective aneuploidogens, inducing both chromosome 

loss and chromosome gain following short exposure to a concentration of 131 ppm. 

(Osgood et al ., 1991 b) . Adult females (2-3 days old) were used. 

Exposures to 0, 10, 30, 50 and 70 min. were carried out. Statistically significant 

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/J 
increases in the frequency of aneuploid offspring were detected following as little as 

10-min . exposure. After 30 and 50 min. exposures, the combined frequency of 

aneuploid offspring was approximately 0.189'o as compared with a control frequency 

of 0.024% a 7-fold increment. 

Acetonitrife was tested in micronucleus test in NMRI mice (13 weeks old) 

(Schlegelmich et al ., 1988). Two dose levels were tested amounting to a 40 and 6096 

LDso (340 and 510 mg/Kg) vie i .p . 

The LDso data were obtained from RTECS. The rat i .p . LDsa value presented in 

RTECS is 850 mg/Kg. For each dose level and day, four male and four female NMRImice. The animals were killed 24, 48 and 72h after injection of a single dose. Bone 

marrow was obtained and the number of micronucleated polychromatic erythrocytes 

was counted by scoring 1000 to 1200 cells per animal from coded slides . 

When the assay was carried out with autoinduction, the mice received daily a 

dose of the acetonitrile equivalent to 5% of the oral LD50 value for 7 days. On the 

eighth day i .p .injection of the high single dose followed . 

Without autoinduction, the number of micronuclei induced by acetonitrile is 

higher than under any other condition, when a dose equivalent to a 60% LDso value 

was administered and the animals were killed 24h after application of the compound. 

The frequency of micronuclei containing polychromatic erythrocytes under these 

conditions reached 4.26 per 1000, compared to 1 .68 per 1000 in negative controls . 

However, autoinduced mice showed a peak nearly as high as this at 72h after 

administration of the compound, but no effect at 24 h after application. This study did 

not include control micronucleus frequencies for comparison to the "induced" levels . 

Peripheral blood samples were obtained from male and female B6C3F1 mice 

treated for 13 weeks with acetonitrile (100, 200, 400 and 800 ppm) by inhalation to 

determine the frequency of micronuclei in 10,000 normochromatic erythrocytes in each 

of 10 animals per dose group. 

Results with female mice were negative but in males, a small but significant 

increase (P<0.006) in micronucleated normochromatic erythrocytes was observed in 

the 400 ppm group (NTP, 1994) . 

4.1 .2 .7.3 . Studies in humans 

There is no information availab'e. 

4.1 .2 .7.4 . Summary of mutagenicity 

There are several data available on the genotoxicity of acetonitrile in vitro 

studies. 

The information in bacteria indicates that acetonitrile is not mutagenic in 

Salmonella assay as well as when the assay is carried out employing a 20 minute 

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preincubation period at 37oC. Acetonitrile neither induces mutations in chinese hamster 

ovary cells or mouse lymphoma L5178Y cells. These tests were conducted with and 

without S9 metabolic activation enzymes. 

In cytogenetic tests with chinese hamster ovary cells, acetonitrile induced slight 

increase in sister chromatid exchanges without S9 and chromosomal aberrations with 

S9 for both endpoint, the increases were noted at the highest dose tested . In the SCE 

assay this increases was considered weak evidence of activity (increase at any single 

dose) . In the chromosomal aberrations test the result was considered equivocal (was 

absence of a statistically significant increase at any one dose) . 

Positive results have been reported in assays which measure the induction of 

aneuploid events. 

Acetonitrile was found to be a potent inducer of aneuploid, but not point 

mutations or recombination in a diploid strain of Saccharomyces cerevisae, although 

relatively high concentrations. 

Acetonitrile induced sex chromosomal aneuploid (both chromosome loss and 

chromosome gain) in oocytes of female Drosophila melanogaster fed an aqueous 

solution of the chemical either as larvae or as adults. 

In addition, weakly positive results were reported in a bone marrow 

micronucleus test with acetonitrile administered by intraperitoneal injection to male and 

female NMR5 mice and a significant increase in micronucleated normochromatic 

erythrocytes was observed in peripheral blood samples from male mice treated with 

acetonitrile for 13 weeks; the frequency of micronucleated erythrocytes in female mice 

was not affected by exposure to acetonitrile . 

In conclusion, acetonitrile did no induce gene mutations in bacteria and showed 

week clastogenic activity in cultured mammalian cells; in vivo, evidence for 

chromosomal damage in mice was observed in the form of increased frecuencies of 

micronucleded erythrocytes, in consequence a possible classification of the substance 

according to EC criteria is Mutagenic, category 3, with risk phrase R40 (possible risk 

of irreversible effects) should be included in the proposal of classification . 

4.1 .2.8. Carcinogenicity 

4.1 .2.8.1 Studies in animals 

The carcinogenicity of acetonitrile has been investiged in rats and mice using 

the inhalation route . These studies were carried out in compliance with the Good 

Laboratory Practice (NTP, 1994) . 

Rats 

From the NTP subchronic rat inhalation study, the following acetonitrile exposure 

levels were selected for the 2-year inhalation study: 100, 200 and 400 ppm, based on 

77 -72- 
reduced survival and gross and histopathologic lesions. 

Groups of 56 male and 56 female Fischer 344 rats were exposed to acetonitrile 

by inhalation at concentrations of 0, 100, 200 or 400 ppm (equivalent to 0, 168, 335 

or 670 mg/m3) for 6 hour per day, 5 days per week for 103 weeks. Eight male and 

eight female rats from each exposure group were evaluated at 15 months. 

The animals were observed twice daily for mortality and signs of toxicity or 

moribundity. Individual clinical observations were recorded every 4 weeks. The animals 

were weighed initially, weekly for the first 13 weeks, and at 4-week intervals thereafter. 

During the final 13 weeks of the study, body weights and clinical findings were 

recorded every 2 weeks. 

Blood for haematology determinations was taken from the retro-orbital sinus of 

rats at the 15-month interim evaluation . 

Necropsies were performed on all animals. Organs weighed at the 15-month 

interim evaluations were liver, lungs, and right kidney. 

Complete histopathologic examinations were performed on all animals. In 

addition to gross lesions and tissue masses with regional lymph nodes, tissues 

examined included: adrenal gland, brain, bone and marrow, clitoral gland, oesophagus, 

heart, kidney, large intestine, larynx, liver lung, lymph nodes; mammary gland, nose, 

ovary, parathyroid gland, pituitary gland, preputial gland, prostate gland, salivary gland, 

seminal vesicle, skin, small intestine spleen, stomach, testis, thymus, thyroid gland, 

trachea, urinary bladder and uterus . 

Survival rates of exposed rats were similar to those of the controls . Exposure 

to acetonitrile by inhalation for 15 months or 2 years had no effect on body weight gain 

or final mean body weights, and the behaviour, general health, and appearance of 

exposed male and female rats were similar to those of the controls throughout the 

study. The were no significant treatment-related effects on absolute or relative organ 

weights . 

At the 15-month interim evaluation, haematocrit values, haemoglobin 

concentration, erythrocyte count, mean erythrocyte volume, and mean erythrocyte 

haemoglobin in 400 ppm female rats were minimally lower than controls . Mean 

erythrocyte volume and mean erythrocyte haemoglobir~ in 400 ppm males were also 

minimally lower than controls ; however, the erythrocyte count was slightly greater than 

that of controls . 

There was no evidence of significant exposure-related nonneoplastic lesions in 

male or female rats at 15 months or 2 year. The only questionable finding was the 

incidences of the hepatocellular adenoma (6%), carcinoma (6%) and adenoma or 

carcinoma (combined 10%) with a statically significant positive trend in male . 

The incidences of hepatocellular adenoma were : 0% at 0 ppm; 2% at 100 ppm; 

-73- 
2% at 200 ppm and 6% at 400 ppm. The incidences of hepatocellular carcinoma were: 

2% at 0 ppm; 0% at 100 ppm; 0% at 200 ppm and 6% at 400 ppm. And the 

incidences of hepatocellular adenoma or Carcinoma (combined) were 2% at 0 ppm; 

2% at 200 ppm and 10% at 400 ppm. 

However pairwise comparisons between exposure groups and controls were not 

significantly different and the incidence of adenoma and carcinoma (combined) in the 

400 ppm group of male was only slightly greater than the historical range for inhalation 

study controls (range 29'0-8%) . 

The incidence of basophilic foci was greater in 200 (P<_0.05) and 400 (P<_0.01) 

ppm males than in controls and the incidences of eosinophilic and mixed cell foci we 

marginally greater in 400 ppm males than in controls. 

The incidences of liver lesions in exposed female groups were similar to 

controls. 

Mice 

From the NTP subchronic mice inhalation study, the following acetonitrile 

exposure levels were selected for the 2-year inhalation study: 50, 100 and 200 ppm, 

based on reduced survival and gross and histopathologic lesions. 

Groups of 60 male and 60 female mice 136C3F1, were exposed to acetonitrile 

by inhalation at concentrations of 0, 50, 100 or 200 ppm/equivalent to 0, 84, 168 or 

335 mg/m3) for 6 hours per day, 5 days per week for 103 weeks. Ten male and ten 

female mice from each exposure group were evaluated at 15 months. 

Clinical examinations, a complete necropsy and microscopic examination were 

performed on all mice. 

Survival rates of exposed female mice and male mice exposed to 50 or 100 

ppm were similar to those of the controls . Survival of male mice in the 200 ppm group 

was significantly greater than that of controls . 

Exposure to acetonitrile by inhalation for up to 2 years had no effect on body 

weight gain or final mean body weights of male and female mice. There were no 

significant treatment-related effects on absolute or relative organ weights. 

There was an increased incidence of alveolar/bronchiolar adenoma in exposed 

male mice. The incidence was significantly increased in 200 ppm male (18/50, 36%) 

and was at the upper limit of the range of historical controls (range 6%-36%, 113/673, 

16 .8%) . 

The incidence of alveolar/bronchiolar adenoma or carcinoma (combined) was 

similarly increased in exposed male mice 21/50 (42%), the range of historical controls 

was 10%-42% (150/673, 22.3%) . In contrast, the incidences of alveolar/bronchiolar 

-74- 
adenoma and adenoma or carcinoma (combined) were inversely related to dose in 

female groups. The incidences in female controls were at the upper range of historical 

controls . 

Proliferative lesions of the alveolar bronchiolar region were present as a 

continuum, with the distinction between hyperplasia, adenoma and carcinoma based 

on the size and morphologic characteristics of the lesion . Thus, a time chemicalrelated increased incidence in this neoplasm type would be expected to manifest as 

an increase in proliferative lesions of all three stages which was not apparent in the 

current study. Although the incidence of alveolar bronchiolar adenomas (18/50, 36%) 

in the 200 ppm male group is equal to the highest incidence seen in previous control 

groups for inhalation studies, the 869'o survival of this group at 2 years was quite high 

and may have contributed to the apparent effect. For these reasons, the increased 

incidence of alveolar bronchiolar adenomas in the 200 ppm males was not attributed 

c to acetonitrile exposure. 

The incidence of hepatocellular carcinoma was greater than controls in males 

exposed to 100 ppm (13/49, 27%) . The incidence of hepatocellular adenoma or 

carcinoma (combined) was similarly increased in 100 ppm males (30/49, 61%) ; this 

increase was significant and exceeded the range for hepatocellular adenoma o 

carcinoma (combined) of historical controls (range 11%-56%; 241/673, 35 .89'0) . 

However, the incidence of hepatocellular neoplasms in the 200 ppm groups was less 

than that in the controls, and there was no indication of an effect of acetonitrile 

exposure on hepatocellular neoplasm in the females. The lack of evidence for a dose 

response in hepatocellular neoplasms in males coupled with an absence of 

confounding factors that would be expected to decrease the neoplasm response, such 

as the markedly lower body weight of 200 ppm males, suggests that this is a sporadic 

finding unrelated to acetonitrile exposure. 

Effects on the forestomach were noted in exposed mice, to acetonitrile . At 15 

month, the incidence of squamous hyperplasia of the forestomach was greater than 

controls in males and females exposed to 50 or 200 ppm; however, the increase was 

only significant in 200 ppm females (P<_0.01) . At 2 years, the increase was dose 

related in exposed groups; the increases were significant in male mice exposed to 200 

ppm (P<_0 .05) and female mice exposed to 100 or 200 ppm (P<_0.01) . 

A few squamous cell papillomas were noted in mice exposed to 100 or 200 

ppm, and one occurred in a control female. The incidences of this benign tumour were 

not statistically significant in males or females and were within the ranges of historical 

controls . 

Thus, these findings establish an effect of prolonged acetonitrile exposure on 

the forestomach of mice, but the magnitude of the neoplastic findings is insufficient to 

attribute to the chemical with any confidence. 

4.1 .2 .8 .2 . Studies in humans 

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00 
Off et al ., 1989 researched lymphatic and haematopoietic tissue cancer in a 

chemical Manufacturing Environment. Exposure Odds Ratios (OR) for non-Hodgkins 

Lymphoma (52 cases), multiple myeloma (20 cases), non-lymphocytic leukaemia (39 

cases) and lymphocytic leukaemia (18 cases) within a cohort of US workers from two 

chemical manufacturing facilities and a research and development centre between 

1940-1978 were examined for twenty-one specific chemicals . For acetonitrile an OR 

of 5.2 was estimated for non-Hodgkins lymphoma (based on two cases), and 2.5 for 

non-lymphocytic leukaemia (based on one case) . 

There was a high likelihood of multiple, concurrent exposure to several 

chemicals in this investigation. 

There was also a high correlation between individuals exposed to "nitriles" and 

individual exposed to "antioxidants" . Due the mixed and varied exposures, it is not 

possible to ascribe any increased tumour incidence solely to acetonitrile exposure. 

4.1 .2.8.3. Summary of carcinogenicity of acetonitrile 

Under the conditions of 2-year inhalation studies in rats, the incidences of 

hepatocellular adenoma (3/48), carcinoma (3/48) and adenoma or carcinoma 

(combined; 5/48) were greater in male rats exposed to 400 ppm than in the controls . 

The incidences of adenoma and carcinoma were within the range of historical controls . 

However, the incidence of adenoma or carcinoma (combined) slightly exceeded the 

range of historical controls (2%-8%). In addition, the incidences of basophilic foci, 

eosinophilic foci, and mixed cell foci were marginally greater than controls in 400 ppm 

males. 

The specific relationship between various hepatocellular foci and neoplasia is 

not clearly understood. However, evidence of chemical-related increased incidences 

of liver foci does provide support for an acetonitrile-related effect on the liver and 

suggest that a liver tumour response is biologically plausible. 

There were no exposure-related liver lesions in female rats . 

There were no increases in the incidences of lung and liver neoplasms in 

exposed groups of mice that were considered related to acetonitrile exposure. 

However, the incidence of squamous hyperplasia of the epithelium of the forestornach 

was significantly increased at 15 months in 200 ppm females. At 2 years, the 

increased incidence was dose related in all exposed male and female groups . 

These findings establish an effect of prolonged acetonitrile exposure on 

forestomach of mice, but the magnitude of the neoplastic findings is insufficient to 

attribute to the chemical with any confidence . 

4.1 .2 .9. Toxicity for reproduction 

4.1 .2 .9.1 . Studies in animals 

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Effects on fertility 

No studies specifically investigating effects on fertility are available. However, 

in a study of Morrissey et al ., 1988, evaluation of rodent sperm, vaginal cytology and 

reproductive organ weight data from National Toxicology Program 13-week studies are 

showed. 

An analysis was conducted of sperm morphology and vaginal cytology 

examinations studies carried out at the end of fifty 13-week studies (25 for rats, 25 for 

mice) over a 3-year period . Reproductive organ weight (testis, epididymis, cauda 

epididymis) and sperm motility were the most statistically powerful endpoints evaluated, 

sperm head morphology may also be a sensitive endpoint for detecting reproductive 

toxicants. 

( Ten male and female Fischer 344 rats or B6C3F1 mice in three dose groups 

plus the control group were utilized .The three dose groups were selected after Day 70 

of the prechronic study. The objective was to select doses which were not causing 

overt toxic effects (mortality or severe depression of body weight or weight gain) . The 

doses used were 100, 200 and 400 ppm and the route of administration was by 

inhalation. Male rats or mice showed no change in (absolute or relative) weight of the 

right cauda or right testis, and no effect on sperm motility . No data are provided on the 

effects of acetonitrile on the female reproductive system rats or mice. 

Coate W.B. (1983), in a unpublished study, indicates no adverse effects were 

seen on sperm motility or morphology or on vaginal cytology in rats or mice exposed 

during 92 days to 0, 25, 50, 100, 200 and 400 ppm acetonitrile by inhalation. 

Developmental studies 

J 

Differents developmental studies were carried out with rats, rabbits and 

hamsters exposed to acetonitrile by differents routes . 

Studies in rats 

The developmental toxicity of acetonitrile was studied in Sprague-Dawley rats 

after inhalation exposure for 6hr/day, during days 6 to 20 of gestation, at dose levels 

of 0, 900, 1200, 1500 and 1800 ppm. The number of animals exposed was 20 per 

dose . 

Maternal lethality occurred at the highest concentration of acetonitrile (1800 ppm) and 

resulted in the death of 8 of the 20 dams (40%) . Maternal body weight gain during 

days 6 to 21 of gestation was significantly reduced at 1800 ppm (p<0.01) . 

Maternal absolute weight gain was significantly reduced at 1500 ppm (p<0 .05) 

and was approximately 60% of that of the controls at 1500 and 1800 ppm. The 

incidence of pregnancy was not significantly altered by exposure to acetonitrile . 

Significant increases in the mean percentage of nonsurviving implants and early 

-77- 
embryonic resorptions were observed at 1800 ppm (p<0.01), concomitant with a 

nonsignificant decrease in the mean number of live fetuses per litter . One litter was 

completely resorbed at 1800 ppm. Exposure to acetonitrile up to 1800 ppm had no 

significant effect on the mean number of implantation sites, fetal sex ratio, or male and 

female fetal weights . One fetus from the control group exhibited exencephaly, unilateral 

exophtalmia and open eyelid .There were no significant changes in the incidences of 

any visceral variations (primarily dilated ureter) or skeletal variations (primaril-extra 

cervical and/or extra lumbar ribs and reduced ossification of sternebra) across 

exposure groups, even at maternally toxic doses. 

For this study the NOAEL for maternal toxicity was 1200 ppm. The NOAF_L 

for developmental toxicity 1800 ppm (Saillenfait et al ., 1993). 

An inhalation developmental toxicity study on acetonitrile was well conducted 

by Mast et al., 1994. Sprague-Dawley rats were exposed to 0, 100, 400 or 1200 ppm 

acetonitrile, 6 hours/day, 7 days/week . Each of the four treatment groups consisted 

of 10 non-pregnant females, 10 positively mated females for a distribution study 

evaluating maternal blood for acetonitrile and cyanide and 33 positively mated females 

for evaluating developmental toxicity . Rats were exposed for 14 consecutive days (6-

19 days of gestation for pregnant animals). Body weights were obtained throughout the 

study period and uterine and fetal body weights were obtained on 20 day of gestation. 

Llve fetuses were sexed and examined for gross, visceral, skeletal and soft-tissue 

craniofacial defects. Acetonitrile and cyanide concentrations were determined in the 

maternal blood of the rats (6/group) on 8 and 18 day gestation. Exposure of rats of 

these concentrations of acetonitrile resulted in mortality in the 1200 ppm group (2/33 

pregnant females; 1/10 non-pregnant females) and the 400 ppm group (1/33 pregnant 

females). However, there were no treatment-related effects upon body weights or 

reproduction indices at any exposure level, nor was there a significant increase in the 

incidence of fetal malformations or variations. The only effect observed in the fetuses 

was a statically significant increase in the incidence of supernumerary ribs in the 

offspring at 100 ppm acetonitrile, there was no dose-response relationship and the 

incidence of this variation at both 400 and 1200 ppm was not different from the control 

group . 

Determination of acetonitrile and cyanide concentrations in maternal rat blood 

showed that acetonitrile concentration in the blood increased with exposure 

concentration for all exposed maternal rats . Detectabie amounts of cyanide in the 

blood were found only in the rats exposed to 1200 ppm acetonitrile (2mg cyanide/ml 

of blood) on 8 day gestation, the concentration declined to 0.8 mg/ml by 18 day 

gestation while acetonitrile concentrations remained essentially constant over the 

exposure period . This decrease in the maternal blood cyanide level may have been 

due to induction of rhodanase, the enzyme thought to be responsible for the 

detoxification of cyanide (Klaasen et al ., 1986) . 

In summary, the two highest exposure concentrations were maternally lethal to 

some rats, however, there was no reduction in body weights, body weight gains, or 

clinical signs of toxicity in surviving pregnant or non-pregnant rats . The no-observable 

-78- 

3 
adverse effect-level (NOAEL) for acetonitrile with respect to developmental toxicity in 

this study was the highest exposure concentrations, 1200 ppm. The maternal NOAEL 

was 100 ppm. 

J 

The developmental toxicity of acetonitrile was examined with an in vivo 

teratology screen adapted for use in the Long-Evans rat (Smith et al ., 1987) . The 

screen was extended to an evaluation of growth till postnatal Days 41-42, and weight 

of several organs at sacrifice. Acetonitrile was dissolved in tricaprylin oil for 

administration at a volume of 0.1 ml/100 g body weight and administered by intubation 

from days 7 to 21 of gestation . The doses used for this study and number of rats were 

0 (155), 50 (20), 150 (20), 300 (22) and 500 (20) mg/Kg bw/day. 

There was maternal toxicity in the two top dose groups (300, 500 mg/kg) . At 300 

mg/kg, 11 females were clearly moribund and therefore were sacrificed at mdgestation, 

t while at 500 mg/kg, 16 females died early in the treatment period ; two deaths also 

occurred in the lowest dose group (50 mg/kg) compared to none of the 155 controls . 

Maternal weight gain was unaffected amongst those in the 50 and 150 mg/kg bw/day 

groups and those survivors in the 300 mg/kg bw/day group. In the 500 mg/kg bw/day 

group there was effect (nonsignificant) on the number of viable litters and on the 

number of litters resorbed. No foetal abnormalities were reported. The only 

observations amongst the pups, which achieved statistical significance, were increased 

pup weight on day 4 (females 500 mg/kg) and increased organ weights on day 41-42 ; 

liver (females 300mg/kg), lung (males 300 mg/kg) and spleen (males unstated group) . 

CD-1 rats were administered daily aqueous solutions of acetonitrile by gavage 

(125, 190 and 275 mg/kg) on gestation days 6-19. Although maternal effects occurred 

at 275 mg/kg bw/day; deaths (2/25), reduced weight gain (2/25), no other maternal 

I o 1 effects were noted in any treated group. Embryotoxic effects, as shown by increases 

J in early resorptions and postimplantation losses, were also noted in the high-dose 

group, statistically significant when compared with historic but not concurrent controls . 

There was apparently no increase in the incidence of foetal abnormalities (no 

data presented) but a slight increase in unossified sternebra in all treated groups 

compared to concurrent, not historic, controls (IRDC, 1981) . 

Rabbits 

J 

A study conducted in compliance with FDA GLP was carried out by Argus 

Research Laboratories, INC (1984) . 

The purpose of this study was to determine the embryo-fetal toxicity and the 

teratogenic potential of acetonitrile in the New Zealand White rabbit . Solutions of 

acetonitrile in reverse osmosis processed deionized water were administered by 

gavage on days 6 through 18 of presumed gestation to artificially inseminated rabbits. 

Acetonitrile was administered to rabbits (25 rabbits/group) at doses o (vehicle) 2, 15 

and 30 mg/Kg/day . 

-79- 

51q 
Animals given the highest dose showed anorexia and decreased body weight 

gain, death in 5 out of 25 rabbits and 2 abortions occurred at this level (30 mg/Kg/day) . 

Body weight gain was also reduced in animals receiving 15 mg/Kg/day, but not 

at the lowest dose level . 

With respect to the fetuses of the treated animals, a significant decrease 

(P=0.011) in the average number of live foetuses/litter and a slight (non-significant 

P>0.05) increase in resorptions was seen in the 30 mg/Kg group . 

Acetonitrile did not adversely affect the incidence of pregnancy or the average 

number of corpora lutea, implantations, average fetal body weight and six ratio . 

No gross external, soft tissue or skeletal malformations or developmental 

variations observed for fetuses were attributed to administration of acetonitrile . 

As compared with control, a significantly increased (P=0 .015) incidence of an 

extra ossification site in the parietal bones was observed for four fetuses in two high 

dosage group litters . The more valid parameter litter incidence, did not demonstrate 

statistical significance (P>0 .05) . This minor variation is frequently observed in this 

strain, of rabbit and was considered spontaneous. 

The maternal NOAEL in this study was 15 mg/Kg bw/d'ay and the NOAEL with 

respect to developmental toxicity 30 mg/Kg b.w./day. 

Hamsters 

In a study by Willhite (1983), pregnant golden hamsters were exposed to 

acetonitrile by inhalation, ingestion or ip injection during the early primitive streak stage 

of embryogenesis. 

In the study by inhalation, hamsters were exposed at 0, 1800, 3800, 5000 or 

8000 ppm acetonitrile during one hour, on the 8th day of gestation. The number of 

animals exposed were 10, 6, 6, 6 and 12 respectively . Maternal deaths occurred at 

3800, 5000 and 8000 ppm (1/6, 1/6 and 3/12 respectively) . 

Resorptions were significantly increased (P<0.05) in the 5000 ppm group . 

Foetal abnormalities were seen in the 5000 ppm group (6, 11 % of foetuses) and 

8000 ppm group (29; 25%) . No abnormalities were seen in either of the other treated 

groups or in the controls . 

The most common abnormalities were exencephaly, Encephelocoele and rib 

fusions. One foetus of the 8000 ppm group had ectopia cordis . 

Average foetal weight was significantly reduced in the 8000 ppm group. 

-80- 

~J 
In this study the maternal NOAEL is 1800 ppm and NOAEL to developmental 

toxicity 3800 ppm. 

When, pregnant golden hamsters were exposed to a single gavage or a single 

intraperitoneal injection of 0, 100, 200, 300 or 400 mg/Kg on the 8th day of gestation, 

maternal toxicity (deaths) occurred at a single gavage dose of 300 mg/Kg (1/6) and 

400 mg/Kg (4/12) . Resorptions were significantly increased in the 200 and 400 mg/Kg 

groups. There was a significant reduction in body-weight gain associated with 

intubation of 100-300 mg/Kg acetonitrile, but there was no significant difference in 

maternal body-weight gain associated with intubation of 400 mg/Kg acetonitrile as 

compared with intubation of an equivalent volume of water. 

The incidence of malformations was significantly increased in the 300 and 400 

mg/Kg groups, two litters of the 100 mg/Kg group also contained abnormal foetuses 

compared to none of those of the control group. Malformed foetuses were recovered 

from dams of the 300 and 400 mg/Kg groups. The skeletal malformations seen 

included rib fusions and severe axial skeleton dysraphic disorders. 

The NOAEL with respect to developmental toxicity was 200 mg/Kg/b.w./day. 

Exposure of pregnant hamsters to acetonitrile by i .p. injection of 100-400 

mg/Kg, failed to result in a significant increase in either the number of malformed 

fetuses or the number of resorbed conception sites as compared with controls. 

There was a significant increase in the average fetal body weight associated 

with i .p. injection of 200-400 mg/Kg acetonitrile when compared to control, the 

relevance of this observation was not clear. There was no significant change in the 

average maternal body weight gain throughout days 8-14 of gestation . 

A low incidence of abnormalities was seen in the 100 mg/Kg group (2; 3% of 

foetuses), 200 mg/Kg group (1 ; 2%) and 400 mg/Kg group (4; 3%). There were no 

abnormalities in the 300 ppm group or in the litters of the 6 control hamsters. 

Abnormalities occurred to the cranium (craniora chischisis), abdominal wall 

(gastroschisis) . The statistical and biological significance of these findings is unclear. 

4.1 .2.9.2 . Studies in humans 

A case-control study of pregnancy outcome among Finnish laboratory workers 

revealed no association between exposure to acetonitrile and increased risk of 

spontaneous abortion in mothers, or malformation and birth weight in their children . 

An odds ratio of 1 .4 (95% Confidence Internal 0.4-4.7) for spontaneous abortion 

for exposure to acetonitrile was estimated when 206 cases were compared to 329 

controls . No association between solvent exposure and risk of malformation was found 

in an analysis of 36 cases and 105 controls, or between solvent exposure and birth 

-81- 

as 
weight, in an analysis of 500 women (Taskinen et al ., 1994) . 

4.1 .2.9.3 . Summary of toxicity for reproduction 

In relation to fertility, there is no information available in humans and there are 

no animal studies specifically investigating such effects. However no changes were 

seen in (absolute or relative) weight of the right cauda or right testis and no effect on 

sperm motility in rats or mice exposed for 13 weeks with 100, 200 and 400 ppm to 

acetonitrile . 

On the other hand, several developmental studies are available in animals . In 

a well conducted study, rats exposed by inhalation to acetonitrile did not result in 

significant foetal effects, event at concentrations which were overtly toxic to the dam. 

In this study a maternal NOAEL: 100 ppm and a NOAEL: 1200 ppm with respect to 

developmental toxicity was established . 

In two studies with pregnant rats that received acetonitrile by gavage no foetal 

abnormalities were reported. 

In other study conducted in compliance with FDA GLP, pregnant rabbits 

administered 2, 15 or 30 mg/Kg acetonitrile orally showed maternal toxicity at 15 and 

30 mg/Kg. Embryotoxicity was observed only at the 30 mg/Kg dose level . There were 

no treatment-related gross external, . soft tissue or skeletal malformations or 

developmental variations. 

Exposure of hamsters to 5000 or 8000 ppm acetonitrile on Day 8 of gestation 

was shown to increase the incidences of resorptions and malformations including 

exencephaly encephalocele and rib fusions. Malformations identical to those noted 

following inhalation exposure occurred sporadically in a limited number of offspring 

after oral or intraperitoneal administration of 100-400 mg/Kg acetonitrile . However, in 

both experiments, teratogenicity was associated with maternal toxicity . Consequently, 

acetonitriie is not considered to be toxic to fetuses at doses below those causing 

maternal toxicity . 

In human, no association between solvent exposure and risk of malformation, 

birth weight or spontaneous abortion has been observed . 

4.1 .3. Risk characterisation 

4.1 .3.0. General aspects 

Acetonitrile is well absorbed from the lungs, gastrointestinal tract and through 

the skin, although there are not available quantitative data. 

Acetonitrile has a widespread distribution . It has been found in heart, lungs, 

liver, spleen, kidneys, stomach, intestines, skin, muscle, brain and teste . Free and 

-82- 

S) 
conjugated hydrogen cyanide were also detected in all the studied organs. 

There are no indications that repeated administrations of acetonitrile result on 

its accumulation in animal tissues. 

The acetonitrile is metabolized to cyanide via cytochrome P-450. Several 

studies have indicated that cyanide formed in vivo is subsequently conjugate with 

thiosulphate to form thiocyanate, which is eliminated in urine. 

The cyanide is responsible for the acetonitrile toxicity . The conversion of 

acetonitrile to cyanide proceeds at a slower rate than that of other nitriles. Interspecies 

variations in toxic response are probably related to the relative speed of cyanide 

formation from acetonitrile . 

( Elimination of acetonitrile occurs primarily through urinary excretion of the 

unchanged compound and free and bound hydrogen cyanide. Pulmonary clearance of 

unchanged acetonitrile via exhalation is also an important pathway of elimination, 

especially at high exposure levels . 

The range of oral LD50 values acetonitrile in mammals is between 160 and 6762 

mg/Kg body weigh . Mouse and Guinea-pig seem to be the most sensitive species. A 

study showed that acetonitrile was more toxic to immature rats (14-day-old) than to 

older rats. The main symptoms in animals appear to be ~prostration followed by 

seizures and convulsions. 

Acetonitrile has rabbit dermal LDso of 1 .25 ml/Kg. It is of interest to note that the 

toxicity by skin penetration is increased when application is made as a aqueous 

solution . 

The 8 h inhalation LCso in male rats is 7500 ppm. Rabbits and mice were more 

sensitive with LCso of 2828 and 2693 ppm and time of exposures of 4 h and 60 min. 

respectively . 

Animals exposed to acetonitrile via different routes of dosing always showed 

respiratory symptoms: rapid and irregular respiration, laboured or difficult breathing and 

intense dyspnoea . 

Some cases of severe intoxications for exposure to high concentrations of 

acetonitrile vapour have been reported . The systemic effects appear to be largely 

attributable to the conversion of acetonitrile to cyanide . Blood cyanide and thiocyanate 

levels are elevated during acute intoxication . 

Acetonitrile is slightly irritant to the skin . When acetonitrile is applied to the eye 

it produces strong vascular injection with edema or slight necrosis. 

Humans accidentally inhaling 500 ppm for brief periods reported some irritation 

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g8' 
to nose and throat . 

Sensitization studies with acetonitrile are not available. 

There is no information available on the effects of repeated exposure to 

acetonitrile in humans. Clinical findings observed on rats and mice exposed to 

acetonitrile for 13 weeks were hypoactivity and ruffled fur during the first week at 

highest concentrations (800 and 1600 ppm) . Female rats exposed to 1600 ppm had 

significantly greater absolute and relative heart, kidney and liver weights than those of 

the controls. In mice this findings appears at 200 ppm. 

In rats clinical pathology findings included anaemia, evidenced by decreases in 

red blood cell count, haemoglobin concentration and haematocrit and lesions consisting 

of congestion, edema and haemorrhage in alveoli at highest concentrations (800 and 

1600 ppm) . 

The NOAEL established to rat was 400 ppm and to mice 100 ppm. This is 

consistent with the results of other subchronic inhalation studies . 

The dose-response for acetonitrile toxicity is quite steep, with little evidence of 

adverse effects in animals exposed to concentrations lower than those that resulted 

in death, or in survivors in exposure groups in which some animals died . 

Acetonitrile did not induce gene mutations in bacteria and showed weak 

clastogenic activity in cultured mammalian cells. However, positive results have been 

reported in assays which measure the induction of aneuploid events, in vitro 

acetonitrile was found to be a potent inducer of aneuploid en Saccharomyces 

cerevisae strain D61 M and in vivo, induced sex chromosomal aneuptody (both 

chromosome loss and chromosome gain) in Drosophila melanogaster. 

In addition, weakly positive results were reported in bone marrow micronucleus 

test with acetonitrile administered by intraperitoneal injection to male and female NMR5 

mice and a significant increase in micronucleated erythrocytes was observed in 

peripheral blood samples from male mice treated with acetonitrile for 13 weeks. 

Moreover, further well-validated in vivo study, in order to detect chromosome damage 

is required . 

The carcinogenicity of acetonitrile via inhalation has been investiged in rats and 

mice . In male F344/N rats exposed to 400 ppm acetonitrile there were a marginal 

increase of neoplasms based on an increased incidence of hepatocellufar adenomas 

and carcinomas. 

There was no evidence of carcinogenic activity of acetonitrile in female F344/N 

rats : exposed to 100, 200 or 400 ppm. 

There were no chemical-related increases in malignant or benign neoplasms 

-84- 
in male or female B6C3F1 mice exposed to 50, 100 or 200 ppm. However, exposure 

of male and female mice to acetonitrile by inhalation resulted in an increased incidence 

of squamous hyperplasia of the forestomach . These findings establish an effect of 

prolonged acetonitrile exposure on the forestomach of mice, but the magnitude of the 

neoplastic findings are insufficient to attribute to the chemical with any confidence. 

In relation to fertility, there is no information available in humans and there are 

no animal studies specifically investigating such effects. However no changes were 

seen in (absolute or relative) weight of the right cauda or right testis and no effect on 

sperm motility in rats or mice exposed for 13 weeks with 100, 200 and 400 ppm to 

acetonitrile . 

On the other hand, several developmental studies are available in animals. In 

rats exposed by inhalation to acetonitrile did not result in significant foetal effects event 

at concentrations which were overtly toxic to the dam. A maternal NOAEL 100 ppm 

and a NOAEL 1200 ppm with respect to developmental toxicity was established . 

Pregnant rabbits administered 2,15 or 30 mg/Kg acetonitrile orally showed 

maternal toxicity at 15 and 30 mg/Kg . Embryotoxicity was observed only at the 30 

mg/Kg dose level. 

There were no treatment-related gross external, soft tissue or skeletal 

malformations or developmental variations. 

Teratogenicity associated with maternal toxicity was observed in two 

experiments carried out with hamsters exposed by inhalation to 5000 or 8000 ppm 

acetonitrile or after oral or intraperitoneal administration of 100-400 mg/Kg acetonitrile . 

In summary acetonitrile is not considered to be toxic to fetuses at doses below 

those causing maternal toxicity . 

The NOAEL of 100 ppm for maternal toxicity and the NOAEL of 1200 ppm for 

developmental toxicity is the same or clearly above of the NOAEL of subchronic 

toxicity respectively . 

Therefore, the risk for those aspects will be covered for the risk characterisation 

of subchronic toxicity . 

In human, no association between solvent exposure and risk of malformation, 

birth weight or spontaneous abortion has been observed . 

In summary, inhalation of acetonitrile produces the characteristical signs and 

symptoms of cyanide intoxication . Data from long and short-term studies showed that 

is a wide variation in inter and intraspecies susceptibility to acetonitrile . 

The results from a well conducted subchronic study shows that mice is one of 

96 -85- 
the most sensitive species to inhaled acetonitrile being the NOAEL 100 ppm . 

Monkeys were more sensitive to acetonitrile than dogs to similar dose in a 99-

days study conducted by Pozzani . 

The Pozzani's human study shows that there is a variability of subjective 

responses of humans to 40,80 and 160 ppm of acetonitrile vapour, suggesting that, 

even if a concentration that would not endanger the health of the majority of workers 

it might cause discomfort to some . 

On the other hand, the dose-response relationship for acetonitrile is quite steep 

with little evidence of adverse effects in animals exposed to concentrations lower than 

that resulted in death . 

4.1 .3.1 . Workers 

Occupational exposure to acetonitrile may occur by inhalation or dermal routes . 

Since acetonitrile is a volatile substance, the most important route is inhalation . 

For risk characterization purposes a NOAEL of 100 ppm is considered. 

The risk assessment for the workplace is based on a NOAEL of 100 ppm . This 

NOAEL is regarded as meaningful, since it have been obtained in one of the most 

sensitive species to inhaled acetonitrile and from a good subchronic inhalation study. 

4.1 .3.1 .1 . Manufacture 

The acetonitrile is produced within an enclosed system . 

Data provided by industry indicate that, in the different work positions, including 

sampling, maintenance and cleaning activities, the 8-hours (TWA) exposure was below 

0.5 ppm. This is 200 times below the NOAEL (100 ppm) . Thus, inhalation exposure in 

the manufacture scenario does not present any grounds for concern in relation to 

health risk to workers. 

Dermal exposure is unexpected . Potential contact could only occur in activities 

that involves breaching the closed system . According with the EASE model, the 

potential dermal exposure is estimated to be low. The general practice is that where 

a contact is expected, gloves are required to avoid absorption through the skin and 

therefore, exposure should be minimal . 

Contact to the eyes should be rather uncommon regarding the industrial 

processes. However, in order to avoid the irritant effect of acetonitrile on eye, face 

shield and/or goggles are expected to be available for employee use in special tasks 

-86- 

916# 
where a contact cannot be excluded. 

Result: 

There is at present no need for further information and/or testing for risk 

reduction measures beyond those which are being applied already. 

4.1 .3.1 .2. End uses 

Most acetonitrile uses are in industrial processes involving closed systems. The 

exposure is expected in special tasks such as sampling, cleaning, maintenance, as the 

precedent section . 

In the exposure section a worst case exposure level of 20 ppm has been 

considered for risk characterization purposes . This is five times below the NOAEL in 

mice of 100 ppm. This ratio seems low for protection of workers, taking into account 

the inter and intraspecies variability, the steeper dose-response curve and the 

suspicion of mutagenicity . 

On the other hand, the exposure level of 20 ppm has been obtained from data 

provided by industry. These data have limited meaningfulness because the processes, 

work practices and the activities involved are not described and information on the 

duration and frequency of exposure is not available . For this reason, more information 

on these exposure aspects is needed to refine the risk assessment. 

Result: 

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

Regarding the use of acetonitrile in chromatography, the exposure value of 7.3 

ppm is 14 times below the NOAEL of 100 ppm, Thus, inhalation exposure is not of 

concern for laboratory workers. 

Following the EASE model dermal exposure will be low. Accordingly with the 

safety data sheet, gloves should be worn to prevent absorption through the skin. 

4.1 .3 .2 . Consumers 

Since acetonitrile is not present in the consumer's products the conclusion ii) is 

applied . 

Result: 

ii) There is at present no need for further information and/or testing for risk 

-87- 
reduction measures beyond those which are being applied already. 

4.1 .3.3 . Man exposed indirectly via the environment 

For the end-points irritation and subchronic toxicity this is not likely to present 

a major health problem. 

Using a NOAEL of 19.5 mg/Kg/day and dose data as reported in 4.1 .1 .3 . we 

can calculate the safety margin for indirectly exposure as follows: 

NOAEL for oral subchronic toxicity/total human dose. 

Model local: 3.7 x 105 

Model regional : 4.6 x 104 

Those values mean high margins of safety indicating no concern on human 

safety after indirect exposure . 

Result: 

There is at present no need for further information and/or testing or for risk 

reduction measures beyond those which are being applied already. 

4.2 . Human health (Physico-chemical properties) 

4.2 .1 . Exposure assessment 

4.2 .1 .1 . Workers 

Due to the fact that acetonitrile is a volatile, highly flammable liquid, can rapidly 

lead to a dangerous concentration build up in air. The acetonitrile forms explosive 

mixtures with air and when is heated to decomposition it emits highly toxic fumes of 

cyanide . In the industrial setting, these risks are not of concern provided that adequate 

safety measures are taken . On the other hand information is already provided on the 

label and in the safety data sheet. 

-88- 

43 
4.2 .1 .2. Consumers 

Acetonitrile has not been detected in consumers products. 

4.2.1 .3. Man exposed indirectly via the environment 

Not applicable. 

4.2.2. Effect assessment 

4.2.2.1 . Explosivity 

Acetonitrile forms explosive mixtures with air . The lower explosive limit is 3.05% 

in volume and the upper explosive limit 17% in volume . 

4.2 .2.2. Flammability 

Acetonitrile is a highly flammable liquid (flash point: 5°C in open cup and 12 .8°C 

in closed cup) with an auto flammability temperature of 524°C. It is a volatile liquid 

(vapour pressure 9.4-9 .8 KPa at 20°C) . 

The vapours can form a flammable mixture with air within the range of 4.4% to 

16 volume %. 

4.2.2.3. Oxidizing potential 

The test method (OECD-EEC) is not applicable to liquid substances. 

4.2.3. Risk characterization (physico-chemical properties) 

Regarding its physico-chemical properties, flammability is a property of concern 

for acetonitrile since it is a volatile liquid which is highly flammable. 

In the industry setting, the flammability risk is not of concern provided adequate 

safety measures are taken . 

Information is provided on the label and in the ,afety data sheet. 

Concerning use by consumers, acetonitrile is not present in the consumer's 

products. 

CONCLUSION 

There is at present no need for further information or testing or for risk reduction 

beyond those which are being applied already . 

-89- 
5. 

(i) 

CONCLUSIONS 

There is a need for further information and/or testing . 

Sensitization 

No data is available on sensitization of acetonitrile . 

Therefore, there is need for testing for skin sensitization in accordance with the 

EU-Annex V-standard. 

Mutagenicitv 

Acetonitrile did no induce gene mutations neither in bacteria nor in mammalian 

cells in culture . Showed week clastogenic activity in cultured mammalian cells . 

However, was found to be a inducer of aneuploid in a diploid strain of 

Saccharomyces cerevisae and in Drosophila melanogaster. In addition, positive 

results, in vivo, were reported in micronucleus test. 

Additional well-validated, in vivo, study in order to detect chromosome damage 

is required, before further conclusions can be made with regard to the risk 

assessment. 

Workers 

This conclusion is reached because the highest levels of exposure obtained in 

the "end uses" scenario have limited meaningfulness since the processes, work 

practices and the activities involved are not described and information on the 

duration and frequency of exposure are not available. 

(ii) There is at present no need for further information and/or testing or for risk 

reduction measures beyond those being applied already . 

This conclusion applies to : 

The environmental risk, with respect to aquatic compartment, including water, 

sediments and biological processes of WWfP. Terrestrial environment, at the 

regional and continental levels, as well as non compartment specific effects 

relevant to the food chain (secondary poisoning) . 

This conclusion also applies to risk to workers involved in the acetonitrile 

manufacture, consumers, risk from indirect exposure of man via the 

environment and from physico-chemical properties . 
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National Toxicology Program (NTP)(1994) . Toxicology and carcinogenesis of 

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by Pseudomonas putfda. Appl. Environ . Microbiol ., 55(9), 2267-2274. 

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several solvents to carp and daphnids. Seitai Kagaku, 4: 45-47 . 

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-98- 
Ohkawa, H., Ohkawa, R., Yamamot, 1 . and Casida, J.E. (1972) . Enzymatic 

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-99- 
. 

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-100- 
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-101- 
APPENDIX A 
p. 107 

USES V1 .0 SINGLE SUBSTANCE 

-- ._. .-----------------. .---------~----------

Printed on : 0~/03/1997 10 :10 

Country : NL 

Substance : acetonitrile 

CAS-No : 75-05-8 

SUBSTANCE IDENTIFICATION 

--- ---~ ---------~-----~----------------- --------- -------._ _

.. _-. ..-_ ._ . _ _.. _. _. _.. 

Name : acetonitrile 

CAS-No : 75-OS-8 

EC-notification no . . 

EINECS no . : 200-835-2 

Molecular weight [g .mol-1] : 41 .05 

Mol . Formula : C2H3N 

PARAMETER STATUS 

Input parameters defaults used . 35 of 59 

Model parameters defaults usea~ . 15 of 15 

Intermediate results overwritten . 9 of 57 

INPUT PARAMETERS 

_ . _- . ... .. .. . . . . . . _. .. ... _ . ... .. . .. . .._ .... . __. . .-. . _ .... . .... . ._. .... ._. . ._ . 

TONNAGE ACTUAL DEFAULT 

--------------

._ ..._ .__..__._ ..-------------------- -~------------- -

Tonnage national [tonnes .yr-1] : 

Tonnage Europe [tonnes .yr-1] : 1 .5e+04 S 

MAIN CATEGORY 

Production : Ic Batch production, dedicated equipment 

Formulation : Ib Dedicated equipment - cleaning iimitea 

Processing : III Non-dispersive use 

INDUSTRIAL CATEGORY 

0 

--------- -------------------------- ---------~-- --- ---- ----~ ---. _. __ -

. ._ _. .. .. .. .-- - ----- ---- Ine . cat . : 3 Chemical industry : chemicals used in sy

ntnesis 

USE CATEGORY 

- -- --- - - - -- ---. _.. __. _ .. _..-~----. _.. _. _..-- --

. _.. _ ._ _. _.. ... .._ _. ._ . .. .- .._ ._ _.. 

Primary : JJ Intermediates 

EMISSION RELEVANT DURING LIFE-CYCLE STEP ? ACTUAL 

------ -

... ..--------- ----------- ------- ------------------~----~--~- ----.. ._.. 

Emission production Yes 

Emission formulation No 

Emission processing . Yes 

`nij.ssior orlvate use . No 

~=mission recovery . No 

Bypass STP . No 

USES V1 .0 NL 03/03/1997 10 :10 

DEFAULT 

No 

No 

No 

No 

No 

No 

Page : 1 

ids 
p. 108 

USES V1 .0 SINGLE SUBSTANCE 

_ .-.--.. _.- ._ ---~---- --.- _

. ._ .. .--- ------

.. .-----------------.. _--._ -

Printed on : 03/0J/1997 10 :10 

Country : NL 

Substance : acetonitrile 

CAS-No : 75-05-8 

PHYSICO-CHEMICAL PROPERTIES : ACTUAL DEFAULT 

-~ -- -- ----- ~------ _

. ..------ -- 

Melt 

. 

ing point [oC] : -45 S "''' 

Vapour pressure [Pa] : 9600 S 0 .001 

Octanol-water part . coeff . (lOlog) [-] - -0-34 S 

Water solubility [mg .l-1] : le+06 S ?? 

Henry`s law constant [Pa .m3 .mo1-1] : 2 .962 S ?? 

Air-water part . coeff . [1 .1-1] : 0 .00125 E ?? 

Solids-water part . ccseff .,i,n soil [l .kg-1] : 0 .005448 E ?? 

Solids-water part . coeff . sediment '[l .kg-1] : 0 .005448 E ?? 

Solids-water part . coeff . susp .mat .[l .kg-1} : 0 .01879 E ?? 

DEGRADATION ACTUAL DEFAULT 

..----~- ----~--___

. .---- .._ .__.-------

._.. .-----------------~~--------- .___. .----- .... ...---.._ ._.-----

.._ ...-~--- .. .- ---~--

DT50 photodeg . in air [d] - 700 S 160 

DT50 hydrolysis in water [d] : 676 S le+ob 

Readily biodegradable . Yes No 

DT50 bioaeg . in water [d] : 15 S ?? 

DT50 b.i,odeg . in .soll [d] : 15 S ?? 

DT50 bioaeg . in STP [d] : 0 .009627 E ?? 

BIOACCUMULATION : ACTUAL DEFAULT 

_.. ..------- ?? BCF--fish [l .kg-i] : 0-3 S 

BCF worm [kg .kg-1] : 0 .3947 E ?? 

BCF stem plant [kg .kg-1] : 0 .3375. . E ?? 

BCF root plant [kg .kg-1] : 2 .889 E ?? 

BCF air plant [m3 .kg-11 : 0 .3242 E ?? 

BCF meat [d .kg-1] . 1 .148e-08 E ?? 

BCF milk [d .kg-1] : 3 .631e-09 E ?? 

ECOTOXICITY : ACTUAL DEFAULT 

_. . _. . .. . ... . .. .. .. . . . . . 

L(E)C50 for frsrn [mg .l-1] : 630 S ?? 

L(E)C50 for crustaceans [mg .l-1] : 101 S ?? 

L(E)C50 for algae ~ [mg .l-1] : 520 S ?? 

L(E)C50 for other aquatic species [mg .l-1] : ?? D ?? 

IC50 for micro-org . in STP [m9 .1-1] : 7500 S ?? 

NOEC for micro-org . in STP [mg .l-1] : ?? D ?? 

NOEC for fish [mg .l-1] : ?? D ?? 

NOEC for crustaceans [mg .l-1] : ?? D ?? 

NOEC for algae [mg .l-1] : ?? D '? 

ACTUAL DEFAULT 

------- ..__ ._ .------

. ._.._.._------~---

._.. .-----------~------------~-----------~_--~--

. ..._ ._.._. . ..__ .__

.._. ...------

~onsump~ion rate testspec:ies [kg .kg-l .d-1] : 0 .1~5 D 0 .125 

-1SE3 V _' .0 NL 0~/0.:~/ 19y7 10 :10 Nage : 

jQq 
p. 109 

USES V1 .0 SINGLE SUBSTANCE 

Printed on : 0;/03/1997 10 :10 

Country : NL 

Substance : acetonitrile 

CAS-No : 75-05-8 

TOXICITY DATA FOR MAMMALS : ACTUAL DEFAULT 

--~~-------------------------------------------- _ -----.. ._----~----- --------- -----_. _ 

LD50 [mg .kg-1(bw)] 175 S 1 

LC50 inhalatory [mg .m-3] : 4524 S ?? 

NOEC in food [mg .kg-1] : 195 E ?? 

Oral NOAEL, non-carcinogens [mg .kg-l .d-1] : 19 .5 S 1 

Is this value a LOAEL ? . No No 

Animal test or human study ? . Animal Animal 

Subchronic or chronic test, ? . Subchronic Subchronic 

NOAEL inhalatory [mg .m-3] : 168 S ?? 

Is this value a LOAEL ? ' . No No 

Animal test or human study ? . Animal Animal 

Subchronic or chronic test ? . . Subchronic Subchronic 

ADI or TDI [mg .kg-l .d-1] : 

Genotoxic or carcinogenic . 

Corrosive or sensitizing . 

Toxic to reproduction . 

vEL man, oral, carcinogens [mg.kg-l .d-1] : 

NEL man, inh ., carcinogens [mg .m-3] : 

?? D ?? 

Yes No 

No No 

No No 

le-05 D le-05 

?? D ?? 

ACTUAL DEFAULT 

--~-- ---~ ------ ---.. _. _---- __- _.---- --- - -- -- ------------ -- --------------------------

Consumption rate testspecies [kg .kg-l .d-1] : 0 .1 D 0 .1 

Scenario . No consumer No consumer 

INTERMEDIATE RESULTS 

exposure exposure 

---- ...------- ._. . .... ._.. .----._-.__. ._ .----~---. ._ ._.__ ._._ .._ .___..-.___... ..___._..._-_. .. .__ ._.. .__..._.._...--- ._. ..__ ._ .._ ._ .._ ._ . .__ .. . ._ ... .... __._... ..----

... . . . . . ... . . 

LOCAL EMISSION ~ OVER- CkLCUWRITE LATED 

_-.-- ~-- ----- -------~- ---~ -------- ---- ---_ _. _.. _. _. _.. ...- ._ ---~--------~---

._. _. _ . _ .....-- -- ---.. _._ _.. _._ _. ._. . ... -..----- --

Step with largest emission to water . Processina 

Release to air [kg .d-1] : 273 .2 U 

Release to waste water [kg .a-1] : 166 .6 0 

Release to surface water [kg .d-1] : 0 

Relea~_-e to soil [kg .d-1] . 3 .35 0 

Number of emission aays [d] . 1 

Distr . factor emission flux to water [-] : 3 .155 

uSES Vl .u NL 03/03/1997 10 :10 Pace : 3 

1iv1 
P. 110 

USES V1 .0 SINGLE SUBSTANCE 

--~--- -------

._._ ..------.. .__..--_--------~--

Printed on : 03/03/1997 10 :10 

Country : NL 

Substance : acetonitrile 

CAS-No : 75-05-8 

REGIONAL EMISSION OVER- CALC:UWRITE LATED 

Release to air [kg .d-1] : 9 .5e+04 0 

Release to waste water [kg .d-1] : 166 .6 0 

Release to surface water [kg .d-1] : 0 

Release to agricultural soil [kg .d-1] : 3 .35 0 

Release to industrial soil [kg .d-1] : 0 

CONTINENTAL EMISSION ~ ~ OVER- C:AL~":U-

' WRITE LATED 

_.. __. ._ .. .- ----~---- -- ------~----.. _--- --- ----------~---. __ .-_------ _ ------------------- --- .__ __ _

.. .._. .- ------- ~- Release to air ' ~ [kg .d-1.] 8 .6be+05 1G .:.IJ 

ne" lease to waste water [kg .d-1] : 500 2466 

Release to surface water [kg .d-1] : 0 

Release to agricultural soil [kg .d-1] : 10 0 

Release to industrial soil [kg .d-1] : 0 

LOCAL EMISSION FROM STP OVER- CALCUWRITE LATED 

Emission STP to air [kg .d-1] : 1 .fJ28 

Emission STP " to water [kg .d-1] : 5 .578 

Emission STP to susp .matter [kg .d-1] : 1 .62e-05 

Emission STP to sludge [kg .d-1] : 0_00__1)8'~S 

REGIONAL EMISSION FROM STP OVER- CALUUWRITE LA 

Emission STP to air [kg .c-1] . 

Emission STP to water . LKg .d-1] . 

E.mis-_ior STP to susp .matter [kg .d-1] : 

Emiss:ort SIP to sludge [kg .d-13 

0 .952 

5 .593 

1 . Eo2ie-05 

0 . 00~53c;, 

~:&'.I7INEr~~~H~ EMiSSION FROM STP OVER- CA_C;UWRITE LATEL) 

Emission S- to ai,- [kg_d-1] . 2,2 

Emission STP to water [kg .c~-1] . 

CRl :.ssion ;:~~FF to susp .matter [kg .d-1] . 4 .87e-05 

Emission STP to sludge [kg . d-1~~ : 0 .01152 

c ;. v 1 , i:i I',J_ Cizi'C%-'/1 c%G 7 10 :10 Page : 

ilift 
-- ...---- ._ .-------~ -------~--~- -~--=-----------.-_..---- ----- USES V1 .0 SINGLE SUBSTANCE 

Printed on : OJ/OJ/1997 10 :10 

Country : NL 

Substance : acetonitrile 

CAS-No : 75-05-8 

LOCAL ENVIRONMENT CONCENTRATIONS 

Cone . influent STP 

Conc . aeration tank 

Cone . 

Cone . 

Cone . 

Cone . 

Co nc . 

Cone . 

:~onc . 

Cone . 

STP 

effluent STP 

sludge STP 

air (100m from STP) 

air (100m from source) 

groundwater 

agricultural soil 

surface water (episode) 

surface water (annual) 

[Mg .l-1] : 

[mg .l-1] . 

[Mg .l-1] : 

[mg . kg-1] : 

[mg .m-3] : 

[ mg m-3] . 

[Mg . 1-11 : 

[mg .kg-1] : 

[mg .l-1] : 

[mg i-1] . 

OVER- CALCUWRITE LATED 

--

92 .5L, 

3 .128 

3 .099 

3 . 349 

7 .826e-07 

0 .0002079 

2 .206e-06 

2 .931e-05 

0 .09683 

0 .0002653 

REGIONAL ENVIRONMENT CONCENTRATIONS 

Cone . 

Cone . 

Cone . 

Cone . 

Cone. . 

Cone . 

air 

s.urface water 

porewater 

natural soil 

aaricultural soil 

inoustr-ial soil 

CONTINENTAL 

Cone . 

Conc . 

Cone . 

"ono . 

Cone . 

Cone . 

LOCAL : 

..one . 

Corl,,: . 

l "~il IL" , 

_, J t -I ,~ . 

ENVIRONMENT 

air 

surface water 

porewater 

natural soil 

agricultural soil 

industrial soil 

CONCE-NTRATIONS IN 

air 

CI'_' I-IKirq w.. ~ er 

Frem 04- plants 

r G, : _ . ~` IJi4~.r ~S 

Inc, ~I 

11- J. I, 

OVERWRITE 

_-

[ mg . m-3] 

[mg 1-1] . 

[mg .l-1] 

[mg .kg-1] 

[Mg .kg-1] 

[mg .kg-1] 

CALCULATED 

~0 .001861 

0 .0006697 

0 .0006c; 13 

0 .0003432 

0 .0002002 

0 .0003432 

CONCENTRATIONS 

HUMAN 

OVER- CALCUWRITE LATED 

[mg m-31 ---------------------- --- -----

[mg .1-1] : 

[mg .l-1] : 

[mg .kg-1] : 

[mg .kg-1] : 

[mg .kg-1] : 

INTAKE MEDIA 

L 

Lmy .K~-i~ : 

[ Mg . kg-1 ~ : 

[Mg .kn-1 

~mg .kg-1] . 

[mg ~u--, - 

0 .0008688 

0 .0002696 

0 .0003109 

0 .0001602 

'-~ . VUl_ e-03 

U . uCjult ": :.~ 

uvE .I .- ~ 

1~+h 

.UU 

0 . 00012 tG5 7-

7 .539e-05 

7 .729e-05 
;:) rir,te0. ,Dr : 

Country 

L 

J 

. .. . 

U3 7 

I'v ~ 

u ~ ~ ~ L7~ 1 i .. . 

LOCAL : INTAKE BY PREDATORS 

Cone . earthworms 

Cone . fish 

water 

LOCAL : HUMAN INTAKE VIA INDIRECT EXPOSURE 

Intake air 

Intake drinking 

Intake fisn 

Intake stem of plant 

intake root of plant 

Intake meat 

Intake milk 

Total human dose 

REGIONAL : CONCENTRATIONS 

Cone . air 

Cone . drinking water 

Cone . fish 

Co-io . s,Leirr ; ot plart.s 

~ .,0~-,c . rGOt of piants 

Cone . meat 

Cone . miik 

C;onc . e,::rtr,worm=_. 

ttGJ1 0NAL . t-ftJI-iHN 

Intake air 

iNTAKt 

: i ~_,, 

- -------~- ---~ ---~--... ...-~--

[mg .kg-1] : 

[mg kg-1] . 

IN 

VIA 

[mg .kg-l .d-1] 

[mg .kg-l .d-1] 

[mg .kg-l .d-1] 

[mg .kg-l .d-1..] 

[mg .kg-l .d-1] 

[mg .kg-l .d-1] 

[mg .kg-l .d-1] 

[mg .kg-l .d-1] 

HUMAN INTAKE 

f m tg rr,-~,1 -

[mg .l-1] : 

[mg-kg-1 ] : 

[mg .kg-1] : 

Lmg .kg-1 ;, : 

[Mg . kc-1 . 

Lmg kg-i ; . 

[mg .kg-1] : 

INDIRECT EXPOSURE 

Lm9-<<g- :--aInt at.: e GrInKI.ng water 

take f is-) 

Inc&~~:e stem of pl,_=,r,t 

~ r~ c a:< e rnot of piar z 

: - ;ta~~-e meat" 

..r'Lw,.~Ke ir~I K 

Tn? a 1 human 

USES V1 .0 NL 

dose 

7mg .kc-

[mg .kg-l .a-1] 

GG- 1 ~ 

," .g-i .d-1 

[Pig . kg-l .d-1] 

[mg .kg-l .d-1] 

0:./03/19c~7 10 : 10 

OVER- CALC:UWRITE LATED 

1 .157e-05 

7 .959e-05 

OVER- CALCUWRITE LATED 

_ ..-- . .

.S 

-_.. .---------- 4 .45e-05 

7 .58e-06 

1 .251e-08 

4 .417e-07 

1 .5e-07 

6 .024e-13 

6 .001e-13 

5 .274e-05 

OVER- uWRI TE ED 

0 .0018b1 

0 .0006913 

O .OuU20Uy 

U . 000b i G8 

u .0005783 

3 .129e-09 

9 .8-4e-lv 

7 . 84ye-05 

lJVtk- t.AL C,lJwRITE LATED 

0 GUUO`~Sc1 . ~~.75e..-G= 

e-08 

J . ~.:1Je-l~G 

1 .024e-06 

5 .363e-12 

5 .343e-12 

0 .0004234 

Page : 13 
p. 113 

USES V1 .0 SINGLE SUBSTANCE 

_ ._. . ._ .. .__ .... . ... . .. .-.___ ._ ... ... .. . 

Printed on : 03/03/1997 10 :10 

Country : NL 

Substance : acetonitrile 

CAS-No : 75-05-8 

NEC ECOSYSTEMS OVER- CALCUWRITt LATEL 

NEC for micro-organisms [mg .1-i] : 

NEC aquatic species [mg .!-1] : 

NEC terrestrial species [mg .kg-1] : 

NEC predator in food [mg .kg-1] : 

IF TOXICITY DATA ON TERRESTRIAL ORGANISMS ARE OvE-:- 

NOT AVAILABLE wri-r 

I NEC terrestrial species (eq . part. . [mc .~ c;- : ~ 

It= T-tE SUBSTANCE IS 

750 

1 .01 

19 .5 

? = 

c~ c ._ c:~ ~- , - 

.... ._. _. ... .... 

:. _- . -ar_or, IC50micro to NL ~7.icro 

Extrapolation L~:5 ;_1 to wZC 

Extrapoia7ion 1-5 --US ~o N,-:C 

SubC:hrOnic Ni:ti, to NEC 

_ 1'-' i_ K = J V L 1 

a ;- Gf ..~,.uot . 

7 L -J = 

[-] -

[- 

.__ ._ . .. ._.__. ._. 

0 .004171 G 

46 .iu 4LS .`'8 

0 .0031i 0 

LOCAL) INTER"fEDIATE DIi-'`, ~ 

__ . . ... . . . . . _ ...._ ... ... . . ... . . . .. .. . .._ ._ ... ... ._. . . ._ ..---------------------------. ._. ._.. .... ._..__ .__ .. ._ ._. . .... ._. .... 

t'iaza.rG quGt . aqua~~iC species 0 .09557 U 

histri.bution factor tor the hazard quot .[-] : 176 .7 176 .7 

?robab :11ty GE, :/NEC > L [-j : 0 .189 U 

T=R~EOTRIAL ECO_7ti'CT~-_M (LOCAL} INTERMEDIATE LIRE .,7 

,:.,-:3ra quot . :.errestriai species 

-)r.~ d;-a quot . terr . species (eq . part .) 1-1 . C . 0 001UiJ2. C 

E ; V .1 .0 NL U5/03/ 19'; 7 10' : 10 

Dva 

OVER- : _ .,-

w~ i`. 1 _ . L ~S I L ~. . 7r,-- . 

age : I 
p. 114 

-_ _

.. ._.. .------- .. ...- .-__ .._ ..._ . .__ .. .._ ._..__._ ..__ ._ ._ . .---

.... ... . .... . 

USES V1 .0 SINGLE S'-i&.STANCE 

_..- .__ . ._. .. .--~--..._.__._ ._._. ._ ._.. . ... ._ ._ ._. - .. .... _ ... . ._ ..._ . . .. .. _..--

Printed on : 03/03/1997 10 :10 

Country : NL 

Substance : acetonitrile 

CAS-No : 75-05-8 

PREDATORS (LOCAL) INTER"iEDIATE DIRECT 

-- -- ._ _ _. . .... ._. . .. .- - - -- .... -- - -- 

... .. . ... . _ _... .- ---... .._ _ . _ _...--- --- -- - ~--- - - --. ._ . _.. ..- - - ._ _.. _. _ ._. ..._ ..... ._ ._.. _ ... _ _ . _. _._ .--

Hazard quot . fi1sh-eating predators [-] : 4 .08ie-06 

Hazard quot . worm-eating predators [-] . 5 .932e-07 

MAN (LOCAL) INTERMEDIATE DIRECT 

----

.. .----------._._ ._ . .. . .---.._.__ ... . .. . ... .._ ..--~--.-._ ._ . .._ ._. .-~----~--.__ .-_._.. .... ._._ ._ . ..... ..._ .._.__. ._. ._ . __ ._ . ..._ .... .__._.. ....---

.. . ..._ ._ ....._. .--~---.._ .... ._. ._.._ .. ... .__ . 

Margin of Safety to, man 0 .1896 ?? 

AQUATIC ECOSYSTEM (REGIONAL) INTERMEDIATE DIRECT 

_- ._. __. .... . . . . ._ ._ _.. ._ .___ ... ._ _ . . .- .. . ._ _...-------- ._. ._.. ._ .__r 

Hazard quot . aquatic species 0 .0006631 6 .b39e-07 

TERF'ESTRIAL ECOSYSTEM (REGIONAL) INTERMEDIATE DIRECT 

Hazard quot . terrestrial species ~o 00 

iya : :ard quet . terr . specles (ec, part . :) [-] : 0 .0006844 4 .47e-07 

PREDATORS (REGIONAL) INTERMEDIATE DIRECT 

. . . . . _ .. ._ . . ... . .._. ... _._ _.. _ . .... ... .... . _.. . .. . ... . ... . ..... _. ... .. ._ .. . . .- ..... . .' . .. .. .. . . _. . .... . .. .. .. .. . 

Hazard quot . fish-eating predators 1 .03e-05 1 .052e-08 

Hazard quot . worm-eating predators [-] : 4 .051e-06 2 .645e-09 

MAN (REGIONAL) 

Margin of Safety for man 

MODEL PARAMETERS 

33 .81; 

_ . . . .. .. .. . .. . --------. .__ . .--- ..._ .__. ._._.._..___- .._ ._ .- ._-_._ .._ ..__ .._ .... ._... . ..-- .--- ... . .... ._--

._.. ._..--~--------------------------_.-._._ .._ .----

JISTRIBUTION PARAMETERS FOR THE LOCAL MODEL : Ai::TUAL DEFAULT 

----------~---------

Size of the local STP [eqj : 1 .2e+04 D 1 .2e+04 

Dilution factor for STG effluent [-" . 32 D 32 

Distr . facto- for diiution [-j : 148 D 148 

Dis--r . factor inTiuent discharge [-] : 41 D 41 

Amount of siucioe applieo [l:g .ha-l .yr-1] : 2000 D 2000 

DISTRIBUTION PA~'AMETERS FOR THE REGIONAL ACTUAL DEFAULT 

JYJIGM . 

Size of the re :~,or~al STP [eq] : le-07 D le+07 

INTERMEDIATE DIRECT 

UC:.C V1 .0 NL 03/05/1997 10 :10 ' ~~age : 
p. 115 

USES V1 .0 - SINGLE SUBSTANCE 

._ _.. ._ _.. .---- - ---_..-------- ---~--------~- - -~-----

Printed on . 03/03/1597 10 :10 

Country : NL 

Substance : acetonitrile 

CAS-No : 75-05-8 

MAN : AC7uhL DEFAULT 

.._ . _._ -------- -- --- .. . .... . .... .--~------ 

_._ . .-----~--..--- 

Daiiy intake of drinking water [m3 .d-1] 0 .002 D 0 .002 

Daily intake of fish [kg .d-1] : 0 .011 D 0 .U11 

Daily intake of leaf crops [kg .d-1] : 0 .4 D 0 .4 

Daily intake of root crops [kg .d-1] : 0 .124 D 0 .124 

Daily intake of meat [kg .d-1] : 0 .12 D 0 .12 

Daily intake of dairy products [kg .d-1] : 0 .378 D 0 .378 

Bioavailability for inhalation [-] : 0 .75 D 0 .75 

Bioavailability for oral exposure [-] : 1 D 1 

Bioavailability for dermal exposure [-] : 1 D 1 

COUNTRY PARAMETERS 

EXTRAPOLATION FACTORS . 

Extrapolation IC50micro to NECmicro 

Extrapolation LC50 to NEC 

Extrapolation ,'-. t_C.`,Os to r~~ECtxtrapoiat : o4,v_C..) . L.er1rJ . at tY'lE: air-wc;ter .Lnter1c.UE [K] . 

i-lvg . wli~C! sPeeu i6m :~, :.>ovr 5ur-face [m .s-1] . 

D :STRiEU' : Ow PARAMETERS FOR THE LOCAL MODEL 

Distribution factor for flushing factor 

DISTRIBUTION Pt;--RAMETtRS FOR THE REGIONAL 

S YS TtI`i 

. ... . __ .. .. . ..... . .. . ... .. .. . .. . .. . . . .. . . . .. . . .... . ._. .. .. ... .. . .. . ... . . . . . . 

TotaA area of the reg . s\,stem [m2] : 

Fra_c_ of reo_ionai area that is water --1 : 

Frac . of t-eg . Gr eG tilCC` ze. I,rYL . soil [-] . 

1-r-au . o-~ ;s agr . soil [-] . 

c-; reg . area that is ind . soil [-] : 

deptn of the reg . water comp . [m] . 

Sum aisch . st.r . crossing sys .bound [m3 .s-1] : 

ACT 

1C 

10 V0 

1 :_) () 

: .T u!-;L 

S 

ACTUAL 

AC i UA ~ 

3 .8e+10 

0 .125 

0 .415 

0 .45 

0 .01 

J 

2600 

.. . .. . .... . ._.. ... _ . _. .. . . ... . _ . ... . ..... .. . .. .. . .... .... _.. .... . - ... .._. .... ..._ .. . . .. . ... .. . ... .. ... .. . ._ . ... ..... .. _. .... . .... ... .. ... . ._ 

USES V10 NL 03/03/1997 10 :10 Pace : 
_ ..--------

.. ..-_-------------~---------

U,S,,ES V1 .0 SINGLE SUGSTANCE 

Printed on : G~/05/1997 10 :10 

Country : NL 

Substance . acetonitrile 

CAS-No : 75-05-8 

p. 116 

DISTRIBUTION PARAMETERS FOR THE REGIONAL AND ACTUAL 

THE CONTINENTAL SYSTEM 

-----------._.-.--------------------. .-------------. ..---------- --

Atmospheric mixing height [m] : 

Mixing depth sediment compartment [m] : 

Mixing depth compartment of nat . soil [m] : . 

Mixing depth compartment of agr . soil [m] : 

Mixing depth compartment of ind . soil [m] : 

Average annual precip~itation [m .s-1] : 

Frac . rain water infiltrates soil ' [-] = . 

Frac . rain water that runs off~soil [-] : 

Dep .velocity aerosol particles [m .s-1] : 

C.onc . of biota in surfacie water [kg .m-3,] : 

Settling velocity susp . particles [m .s-1] : 

_ _ .-_. .... .--- 1000 

0 .03 

0 .05 

0 .2 

0 .05 

51e-08 

0 .4 

0 .5 

0 .001 

0 .001 

89e-05 

DISTRIBUTION PARAMETERS FOR THE STP MODEL ACTUAL 

(IN/OUT) 

Waste water per inhabitant [m3 .d-1] 

. 

Surplus sludge per inn . equiv .[kg .d-l .eq-1] : 

0 .15 

0 .0355 

ORGANISMS ACTUAL 

Daily intake of soil by cattle [kg-d-1] : 0 .41 

Daily intake of grass by cattle [kg .d-1] : 16 .9 

Daily intake of air by cattle [m_d-i] : 1<< 

Daily ventilation rate [m3 .d-1] : 20 

Average human bodyweight [kg] : 70 

_..----------- --------------------- - --- 

USES v'1 .0 NL 03%03,'1997 10 :10 

III 

Page : 10