Octadecyl methacrylate

Endpoint summary

Additional information

For the assessment of octadecyl methacrylate there are data of the structurally related substances isodecyl methacrylate (three in vitro studies) and monomer mix (methacrylic acid ester of an alcohol mixture with an average C-number of 14,8) available (two in vitro studies).

One reverse mutation assay in bacteria, one chromosome aberration test and one HPRT test with the structurally related substance isodecyl methacrylate are available. With monomer mix as test substance one reverse mutation assay in bacteria and one chromosome aberration test in V79 cells are available.

In vivo there are two micronucleus studies with structural analogue dodecyl methacrylate and one study with octadecyl methacrylate available.

 

Bacterial reverse mutation assay

No study is available on octadecyl methacrylate but there are two studies on the structurally related substances isodecyl methacrylate and monomer mix.

In a reverse gene mutation assay in bacteria according to OECD guideline 471 Salmonella typhimurium TA98, TA100, TA1535, TA1537 and TA102 strains were exposed to isodecyl methacrylate in THF at concentrations up to 5000 µg/plate in the presence and absence of mammalian metabolic activation. The positive controls induced the appropriate responses in the corresponding strains. There was no evidence of induced mutant colonies over background (Klimisch score: 1, GLP, (RCC-CCR, 2008)).

In a reverse gene mutation assay in bacteria according to OECD guideline 471 Salmonella typhimurium TA98, TA100, TA1535, TA1537 and TA102 strains were exposed to monomer mix in THF at concentrations up to 3000 µg/plate in the presence and absence of mammalian metabolic activation. The positive controls induced the appropriate responses in the corresponding strains. There was no evidence of induced mutant colonies over background (Klimisch score: 1, GLP, (RCC-CCR, 2005)).

 

In vitro Chromosome aberration test in human lymphocytes

No study is available on octadecyl methacrylate but there is a study on the structurally related substance isodecyl methacrylate.

 

In a chromosome aberration test in human lymphocytes according to OECD guideline 473 (adopted May 26, 1983), human lymphocyte cultures were exposed to isodecyl methacrylate (98.9%) in THF with and without metabolic activation (S9 mix).

The following concentrations were evaluated:

Experiment I:

22 hrs prep. interval, 4 h treatment without metabolic activation: 14.5, 25.4, 44.4, 77.7, 136.0, 238.1, 416.7, 729.1, 1276.0, 2233 µg/ml

22 hrs prep. interval, 4 h treatment with metabolic activation: 14.5, 25.4, 44.4, 77.7, 136.0, 238.1, 416.7, 729.1, 1276.0, 2233 µg/ml

Experiment II:

22 hrs prep. interval, 22 h treatment without metabolic activation: 44.4, 77.7, 136.0, 238.1, 416.7, 729.1, 1276.0, 2233 µg/ml

22 hrs prep. interval, 4 h treatment with metabolic activation: 44.4, 77.7, 136.0, 238.1, 416.7, 729.1, 1276.0, 2233 µg/ml

In Experiment I, visible precipitation of the test item in the culture medium was observed at 136.0 µg/ml and above in the absence and presence of S9 mix. In addition, precipitation occurred in Experiment II, in the absence of S9 mix, at 136.0 µg/ml and above and in the presence of S9 mix at 416.7 µg/ml and above. No relevant increase in the osmolarity or pH value was observed. In Experiment I, in the absence and presence of S9 mix, and in Experiment II, in the presence of S9 mix, no cytotoxicity was observed up to the highest applied concentration. In Experiment II, in the absence of S9 mix, a single clearly reduced mitotic index was observed at the highest dose evaluated for cytogenetic damage.

Isodecyl methacrylate was tested up to cytotoxic concentration.

 

In the absence and presence of S9 mix neither a statistically nor a biologically relevant increase in the number of cells carrying structural chromosome aberrations were observed after treatment with the test item (Klimisch score: 1, GLP, (RCC-CCR, 2008))

In vitro Chromosome aberration test in Chinese hamster V79 cells

No study is available with octadecyl methacrylate but there is a study with a structurally related substance, monomer mix (details on composition see above).

 

In a chromosome aberration test in Chinese hamster V79 cells according to OECD guideline 473 (adopted July 21, 1997), human lymphocyte cultures were exposed to monomer mix dissolved in THF with and without metabolic activation (S9 mix).

The following concentrations were evaluated:

Experiment I:

18 hrs prep. interval, 4 h treatment without and with metabolic activation: 5.9, 11.7, 23.4, 46.9, 93.8, 187.5 (p), 375.0 (p), 750.0 (p), 1500.0 (p), 3000.0 (p) µg/ml (p): Precipitation occurred

Experiment II:

18 hrs prep. interval, 18 h treatment without metabolic activation: 46.9, 93.8, 187.5 (p), 375.0 (p), 750.0 (p), 1500.0 (p), 3000.0 (p µg/ml

28 hrs prep. interval, 28 h treatment without metabolic activation: 23.4, 46.9, 93.8, 187.5 (p), 375.0 (p), 750.0 (p), 1500.0 (p), 3000.0 (p) µg/ml

Experiment II: 28 hrs prep. interval, 4 hrs exposure period: with S9 mix: 23.4, 46.9, 93.8, 187.5 (p), 375.0 (p), 750.0 (p) µg/ml

(p): Precipitation occurred

No clear toxic effects indicated by reduced mitotic indices or cell numbers of below 50% were observed up to the highest required test item concentration. Therefore, concentrations at the border of test item solubility in culture medium were scored for cytogenetic damage.

 

In both independent experiments, no biologically relevant increase in the number of cells carrying structural chromosomal aberrations was observed after treatment with the test item. However, in Experiments I and II, in the absence of S9 mix, statistically significant increases (2 % - 2.5 % aberrant cells, exclusive gaps) were observed, but were within our historical control range (0.0 - 4.0 % aberrant cells, exclusive gaps) and are regarded as being biologically irrelevant.

 

No relevant increase in the frequencies of polyploid metaphases was found after treatment with the test item as compared to the frequencies of the controls.

 

In the absence and presence of S9 mix neither a statistically nor a biologically relevant increase in the number of cells carrying structural chromosome aberrations were observed after treatment with the test item (Klimisch score: 1, GLP, (RCC-CCR, 2005))

HPRT-test in mammalian cells

No study is available with octadecyl methacrylate but there is a study with the structurally related substance isodecyl methacrylate.

Isodecyl methacrylate was assessed for its potential to induce gene mutations at the HPRT locus using V79 cells of the Chinese hamster according to OECD 476.

The assay was performed in two independent experiments with identical experimental procedures, using two parallel cultures each. The first main experiment was performed with and without liver microsomal activation and a treatment period of 4 h. The second experiment was performed with a treatment period of 24 hours in the absence of metabolic activation and 4 hours in the presence of metabolic activation.

The cell cultures were evaluated at the following concentrations:

Experiment I:

without S9 mix:  0.1; 0.3; 0.5; 1.0; and 2.0 µg/ml

with S9 mix: 37.5; 75; 150; 300; and 1200 µg/ml

 

Experiment II:

without S9 mix: 18.8 ;37.5; 75.0; 150; and 600 µg/ml

with S9 mix: 37.5; 75.0; 150; 300; and 600 µg/ml

In both experiments of this study (with and without S9 mix) the range of the solvent controls was from 5.7 up to 24.0 mutants per 10⁶cells; the range of the groups treated with the test item was from 3.3 up to 34.1 mutants per 10⁶cells.

 

EMS (150 µg/mL in experiment I and 75 µg/mL in experiment II) and DMBA (2.0 µg/mL) were used as positive controls and showed a distinct increase in induced mutant colonies. This showed the sensitivity of the test system and the activity of the S9 mix.

 

In conclusion it can be stated that under the experimental conditions reported the test item did not induce gene mutations at the HPRT locus in V79 cells.

 

In vivo Micronucleus test

In a NMRI mouse bone marrow micronucleus assay, 5 animals/male/female/dose were treated orally with structural analogue dodecyl methacrylate (98%, stabilized) at a dose of 0, 5000 mg/kg bw according to OECD 474. The test article was suspended in carboxymethyl cellulose (1%). This suspending agent was used as negative control. The volume administered orally was 10 ml/kg b.w.. 24 h, 48 h and 72 h after a single application of the test article the bone marrow cells were collected for micronuclei analysis. Ten animals (5 males, 5 females) per test group were evaluated for the occurrence of micronuclei. 1000 polychromatic erythrocytes (PCE) per animal were scored for micronuclei.

To describe a cytotoxic effect due to the treatment with the test article the ratio between polychromatic and normochromatic erythrocytes (NCE) was determined in the same sample and reported as the number of NCE per 1000 PCE.

The following dose level of the test article was investigated:

24 h, 48 h, and 72 h preparation interval: 5000 mg/kg b.w..

In a pre-experiment this dose level was estimated to be the maximum attainable dose. The animals expressed toxic reactions. After treatment with the test article the ratio between PCEs and NCEs was not affected as compared to the corresponding negative controls thus indicating no cytotoxic effects.

In comparison with the corresponding negative controls there was no enhancement in the frequency of the detected micronuclei at any preparation interval after application of the test article.

An appropriate reference mutagen was used as positive control which showed a distinct increase of induced micronucleus frequency. 

This study is classified as acceptable. It satisfies the requirement for Test Guideline OECD 474 for in vivo cytogenetic mutagenicity data.

Therefore, dodecyl methacrylate is considered to be non-mutagenic in this micronucleus assay.

In a second NMRI mouse bone marrow micronucleus assay, 5 animals/male/female/dose were treated orally with octadecyl methacrylate (98%, stabilized) at a dose of 0, 5000 mg/kg bw according to OECD 474. The test article was suspended in PEG. This suspending agent was used as negative control. The volume administered orally was 10 ml/kg b.w.. 24 h, 48 h and 72 h after a single application of the test article the bone marrow cells were collected for micronuclei analysis. Ten animals (5 males, 5 females) per test group were evaluated for the occurrence of micronuclei. 1000 polychromatic erythrocytes (PCE) per animal were scored for micronuclei.

To describe a cytotoxic effect due to the treatment with the test article the ratio between polychromatic and normochromatic erythrocytes (NCE) was determined in the same sample and reported as the number of NCE per 1000 PCE.

The following dose level of the test article was investigated:

24 h, 48 h, and 72 h preparation interval: 5000 mg/kg b.w..

In a pre-experiment this dose level was estimated to be the maximum attainable dose. The animals expressed toxic reactions. After treatment with the test article the ratio between PCEs and NCEs was not affected as compared to the corresponding negative controls thus indicating no cytotoxic effects.

In comparison with the corresponding negative controls there was no enhancement in the frequency of the detected micronuclei at any preparation interval after application of the test article.

An appropriate reference mutagen was used as positive control which showed a distinct increase of induced micronucleus frequency. 

This study is classified as acceptable. It satisfies the requirement for Test Guideline OECD 474 for in vivo cytogenetic mutagenicity data.

Therefore, octadecyl methacrylate is considered to be non-mutagenic in this micronucleus assay.

Conclusion:

The absence of a mutagenic potential was demonstrated for gene mutations as well as chromosome mutations for isodecyl methacrylate and monomer mix.

These results are also representative for octadecyl methacrylate as isodecyl methacrylate represents a worst-case in terms of bioavailability due to its molecular size, lipophilicity and water solubility.

A negative mouse micronucleus tests with dodecyl methacrylate and octadecyl methacrylate supports the absence of a mutagenic potential in vivo.

Short description of key information:
There are several studies available for structural analogue substances dodecyl methacrylate, isodecyl methacrylate as well as monomer mix (methacrylic acid ester of an alcohol mixture with an average C-number of 14.8) and one study with octadecyl methacrylate.
No single key study has been selected for in vitro genetic toxicity; instead, all available studies have been used in a weight-of-evidence approach.
Read-across in vitro:
In three different reliable (Klimisch score: 1, with GLP) in vitro genetic toxicity studies with isodecyl methacrylate (structurally related substance of octadecyl methacrylate) received negative results. Furthermore there are two additional in vitro studies with Monomer mix (Klimisch score: 1, GLP) which received negative results as well.

Genetic toxicity data in vivo:
Mouse micronucleus test, OECD474 with structural analogue dodecyl methacrylate: negative (Klimisch score: 1, GLP, (RCC-CCR, 1989))
Mouse micronucleus test, OECD474 with octadecyl methacrylate: negative (Klimisch score: 1, GLP, (CCR, 1989))

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

Based on the reliable available data on structural analogue substances dodecyl methacrylate, isodecyl methacrylate, monomer mix (structurally related substances of octadecyl methacrylate) and octadecyl methacrylate, octadecyl methacrylate does not need to be classified for mutagenicity

according to the criteria given in regulation (EC) 1272/2008 (CLP (EU-GHS) or the former European directive on classification and labelling 67/548/EEC. Thus, no labelling is required.