May 20, 2009 

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Assessment of skin sensitizing potential of capsules 

Available data in animals and humans on the skin sensitization potential of monomers 

used in PMMA capsules have been reviewed. For the skin sensitizing monomers 

a risk assessment has been developed to ensure the safe use of 

capsules in fabric softener. A margin of safety has been calculated by means of 

the ratio between the derived no-observed-adverse-effect-level (NOAEL) for skin 

sensitization and the estimated consumer exposure: 

MMA BUDA 

NOAEL skin sensitization 11750 1Jg/cm2 78.7 1Jg/cm2 

Estimated consumer exposure 0.09 ng/cm2 0.05 ng/cm2 

Margin of safety 130 X 106 2 X 106 

has been reported conclusively to cause skin sensitization in animals and 

humans. However, could not be detected as residual monomer in 

capsules. To provide a qualitative risk assessment it was assumed that and 

are similar regarding skin sensitizing potency. Consumer exposure based on the 

detection limit of the analytical method used for determination (1 00 ppm) 

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The margin of safety of all three monomers is estimated to be 

well above 106. In consequence, it is considered very unlikely that skin sensitization to 

any of the three monomers occurs by contact with capsules used in fabric 

softeners. 

Yours sincerelv. 

Annex 1: Derivation of a No-Adverse-Effect-Level from experimental data 

Annex II: Exposure Assessment 
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Annex 1: Derivation of a No-Adverse-Effect-Level from experimental data 

has been tested extensively for skin sensitization in guinea pig models and in the 

murine Local Lymph Node Assay (LLNA). Positive reactions in guinea pig tests were 

obtained in tests using adjuvants, especially when high induction and challenge 

concentration were used. The purity of the used and its stabilizer content were not 

specified in most of the guinea pig studies. In the LLNA of high purity (99.96%) 

was used, why data from the LLNA study have been chosen as point of departure for 

derivation of a no-observed-adverse-effect-concentration (NOAEC). 

In humans, no skin sensitization has been tested by Human Repeat Insult Patch Test or 

Human Maximization Test; however human patch tests gave clear evidence that 

is skin sensitizing to humans. However, in terms of potency it is considered a weak skin 

sensitizer. 

In the LLNA was tested in two vehicles, acetone:olive oil 4:1 (AOO) and acetone 

alone (Betts et al. 2006). To err on the safe side only data obtained with acetone as a 

vehicle will be considered since stimulation indices with this vehicle were higher than 

those obtained with AOO. From the published data an EC3 of 60% an a NOAEC 

(defined as concentration which did not exceed a stimulation index of 3) of 50% can be 

derived. 

The NOAEC (%)can be converted to dose per skin area (j.Jg/cm2) by considering the 

dose volume of 25 j.JI (standard LLNA protocol), and an estimated application area of 1 

cm2 for the mouse ear, and the density of 1 ,4-butanediol diacrylate (0.94 mg/cm3) : 

NOAEC (%) x 10 x density x 25 j.Jg/cm2 =dose per skin area [1Jg/cm2] 

Thus, a NOAEC of 50% MMA accounts for 50% x 10 x 0.94 x 25 = 11750 1-19 MMA/cm2 
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In a second guinea pig maximization test 10 animals were treated with 10% (w/w) 

n arachis oil for intradermal induction and 2% (w/w) in petrolatum or 80% 

ethanol (not further specified) for the epicutane induction. After challenge with 0.6% 

(w/w) in methyl ethyl ketone/arachis oil (2: 1) no positive skin reaction was 

observed in all10 tested guinea pigs (van der Walle et al., 1983). 

Additional data are available from Freund's Complete Adjuvant Test (van der Walle et 

al., 1983). On days 0, 2, 4, 7 and 9 intradermal injections with 0.1 ml containing 10% 

(w/w) in Freund's Complete Adjuvant were performed for induction in up to 8 

guinea pigs. Challenge was performed epicutaneously on day 21 with 0.6% (w/w) 

in methyl ethyl ketone/arachis oil (2:1). Depending on the purity of the test 

substance a positive reaction for skin sensitization was observed in 1 out of 7 (14%) or 

5 out of 8 (63%) tested animals in 98% or 95% pure test substance, respectively (van 

derWalle et al., 1983). 

Over the past 20 years the skin sensitizing effects of in human has been 

documented in numerous case reports and statistical analysis of patch tests performed 

on patients with occupational contact dermatitis or contact dermatitis acquired away 

from the workplace. The Information Network of Departments of Dermatology reported 

10 positive patch test results out of 483 tested patients (IVDK 2000) and Kanerva et al. 

reported 11 positive results out of 242 tested patients (Kanerva et al. 1997). 

Neither of the available positive test results from guinea pig testing or human patch 

tests allow to derive a concentration of on which a risk assessment can be 

based. For this purpose a murine Local Lymph Node Assay (LLNA) has been 

conducted to derive a BUDA concentration at which a skin sensitisation is considered 

likely. The LLNA was performed according to the OECD test guideline 429. Five CBA/J 

mice per dose group (1 %, 0.3%, and 0.1% in methyl ethyl ketone) plus a vehicle control 

group have been treated on the same application site for three consecutive Three 

days after the last injection all test groups received an intravenous injection of Hthymidine into the tail vein. Five hours after the thymidine injection the study was 

terminated an the ear weight, lymph node weight as well as the cell count and the 

incorporated radioactivity in the cell population of the draining auricular lymph nodes 
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The NOAEC from the LLNA is converted to dose per skin area (1Jg/cm2) by considering 

the dose volume of 25 1-11 (standard LLNA protocol}, and an estimated application area 

of 1 cm2 for the mouse ear, and the density of (1.049 mg/cm3): 

NOAEC (%) x 10 x density x 25 j.Jg/cm2 =dose per skin area [1Jg/cm2] 

Thus, the NOAEL of 0.3% BUDA accounts for 

0.3% X 10 X 1.049 X 25 = 78.71JQ 

Numerous studies in guinea pigs show that 1as a skin sensitizing potential. 

When a concentration of 1% (w/w) in olive oil/acetone (9: 1) was used for the 

intradermal induction and 25% (w/w) in petrolatum for the epicutane induction were 

chosen 10 out of 15 (67%) tested guinea pigs showed a positive reaction for skin 

sensitization after challenge with 0.2% (w/w) in petrolatum (Bjorkner, 1984). No 

positive reaction (0 out of 15) was observed when 0.2% (w/w) in acetone was 

used for challenge after induction with the same concentrations described above. The 

discrepancy between the vehicle dependent test results was attributed to the 

polymerization process of the acrylic compounds in petrolatum and acetone and it was 

assumed that the petrolatum vehicle increased the rate of positive challenge results by 

preventing the polymerization of the acrylic monomer (Bjorkner and Niklasson, 1984). 

Over the past 30 years the skin sensitizing effects of in humans has been 

documented in numerous case reports and statistical analysis of patch tests performed 

on patients with occupational contact dermatitis or contact dermatitis acquired away 

from the workplace. The Information Network of Departments of Dermatology reported 

5 positive patch test results out of 369 tested patients (IVDK 1997) and Kanerva et al. 

reported 2 positive results out of 124 tested patients (Kanerva et al. 1995). 

None of the available studies allows for the derivation of a NOAEC. For the sake of this 

risk assessment it is assumed that may have the same skin sensitizing potential 

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Based on the available human patch test data and guinea pig 
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References 

Betts CJ, Dearman RJ, Heylings JR, Kimber I, Basketter DA (2006). Skin sensitization 

potency of methyl methacrylate in the local lymph node assay: comparisons with 

guinea-pig data and human experience. Contact Derm, 55, 140-147. 

Bjorkner B (1984). The sensitizing capacity of multifunctional acrylates in the guinea 

pig. Contact Derm, 11, 236- 246. 

Bjorkner Band Niklasson B (1984). Influence of the vehicle on elicitation of contact 

allergic reactions to acrylic compounds in the guinea pig. Contact Derm, 11, 268-

278. 

IVDK (lnfonnationsverbund Dennatologischer Kliniken) (1997). Auswertung der 

zwischen 1992 und 1995 vom IVDK erfassten Daten zu Pentaerythrittiracrylat, 

16.01.1997, IVDK, Gottingen. 

IVDK (lnfonnationsverbund Dennatologischer Kliniken) (2000). Auswertung der 

zwischen 1992 und 1998 vom IVDK erfassten Daten, 7.2.2000, IVDK, Gottingen. 

Kanerva L, Estlander T, Jolanki R, Tarvainen K (1995). Statistics on allergic patch test 

reactions caused by acrylate compounds, including data on ethyl methacrylate. Am. 

J. Contact Dermatitis 6, 75-77. 

Kanerva L, Jolanki R, Estlander T ( 1997) 10 years of patch testing with the 

(meth)acrylate series. Contact Dermatitis 37, 255-258. 

Van der Walle HB, Waegemaekers T, Bensink T (1983). Sensitizing potential of 12 

di(meth)acrylates in the guinea pig. Contact Derm 9, 10 - 20. 
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Annex II: Exposure Assessment 

Estimated consumer exposure resulting from the use of :apsule in 

The consumer exposure models (equations) and consumer exposure factors used in 

this document are taken from the Appendix D and Appendix G, respectively, of the 

guidance document methodology for human & environmental risk assessment on 

ingredients of household cleaning products (HERA, 2005). 

Use of . capsule 

capsule will be used in fabric softeners at a concentration of 2.5%. Most 

conservative assumptions have been used (HERA, 2005; EU, 2003) to estimate the 

consumer exposures, namely the dermal exposure while wearing machine laundered 

garment with PMMA capsule deposited on the inner surface. 

Dermal exposure of adults wearing machine-washed fabric 

Dermal exposure (EXP) to capsules via indirect skin contact from wearing 

machine-washed clothes is calculated in mg ::apsule per day by the formula: 

F1 percentage(%) weight fraction of substance in product: 2.5%. 

C' product load, in mg/cm2: 

Data not available, but can be estimated as described below: 

Estimation of product load C' when product is applied to skin by wearing 

machine-washed fabrics: 

C' = (M x F' x FD) I W1 

M maximum amount of fabric softener used per washing cycle, in mg: 

140 g = 140 x 103 mg (EU, 2003). 

F' percentage(%) weight fraction of substance (PMMA capsule) deposited 

on fabric during the washing process: 100% (worst case). 

FD fabric density, in mg/cm2 ;;; 23 mg/cm2 

Approximate weight of medium weight cotton fabric 

w1 total weight fabric, in mg: 3.1 x 106 mg. 
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capsule are very unlikely to be absorbed through the skin, therefore risk for skin 

sensitisation will be calculated based on the migration rate of the residual starting 

material of the capsule. 

Based on the calculated exposure to capsule per day the exposure to the 

residual starting material can be estimated based on their residual levels and migration 

rate. 

Estimated exposure for 

For MMA a residual monomer level of 330 ppm has been determined. To err on the 

safe side it is assumed that MMA penetrates to 1 00% through the skin 

= 4.6 mg PMMA capsule/day x 330 ng MMA/mg PMMA capsule 

= 1518 ng fday 

Given a total exposed skin area of 17600 cm2 the topical concentration of MMA 

migrating out of PMMA capsules results in 

1518 ng MMA/day/17600 cm2 = 0.086 ng 'cm2 

Estimated exposure for 

For BUDA a residual monomer level of 200 ppm has been determined. To err on the 

safe side it is assumed that penetrates to 100% through the skin 

EXPsuoA = 4.6 mg 

= 920 ng 

capsule/day x 200 ng 

'day 

rmg capsule 

Given a total exposed skin area of 17600 cm2 the topical concentration of 

migrating out of PMMA capsules results in 

920 ng BUDA/day/17600 cm2 = 0.052 ng rcm2 

Estimated exposure for 

For no residual monomer has been found. For the purpose of this risk 

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References 

HERA (2005). Guidance Document Methodology for Human & Environmental Risk 

Assessment on Ingredients of Household Cleaning Products (HERA), February 

2005. Accessible through the website of the International Association for Soaps, 

Detergents and Maintenance Products (http://www.aise-net.orgQ. 

EU (2003). Technical Guidance Document on Risk Assessment in support of 

Commission Directive 93/67/EEC on Risk Assessment for new notified substances 

[ ... ] Part I, lspra, Italy 2003.