Octadecyl methacrylate

Endpoint summary

Description of key information

Skin irritation: classification: not irritating; Evaluation  in a weight of evidence approach with structurally related long-chain alkyl methacrylates three studies according to Appraisal of the Safety of Chemicals in Foods, Drugs  and Cosmetics, FDA Draize (1959); one study according to OECD guideline 404; GLP
Eye irritation: not irritating. Evaluation  in a weight of evidence approach with structurally related long-chain alkyl methacrylates: one study according to Appraisal of the Safety of Chemicals in Foods, Drugs  and Cosmetics, FDA Draize (1959); one study according to OECD guideline 405; GLP

Key value for chemical safety assessment

Skin irritation / corrosion

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Eye irritation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Skin irritation

 

Non human information

One study on skin irritation potential is available of the single substance octadecyl methacrylate. Further studies on skin irritation were assessed in a weight of evidence approach with three available studies for structurally related long-chain alkyl methacrylates: Three studies according to Appraisal of the Safety of Chemicals in foods, drugs and cosmetics, FDA Draize (1959) with methacrylic acid ester of an alcohol mixture with a mean C-number of 12,6, CAS: 90551-76-1 ( 65 % dodecyl methacrylate, 25 % tetradecyl methacrylate, 10 % higher alkyl methacrylates up to octadecyl methacrylate), with methacrylic acid ester of an alcohol mixture with a mean C-number of 14,2, CAS: 90551-77 -2 ( 18 % dodecyl methacrylate, 21 % esters of C13 -alcohols, 28 % tetradecyl methacrylate, 30 % higher alkyl methacrylates up to octadecyl methacrylate) and with octadecyl methacrylate (CAS: 32360-05-7) and one study acc. OECD 404 with the structurally related substance isotridecyl methacrylate.

Only the data for the shaved, intact skin were used for evaluation. In studies carried out with more than 3 animals both approaches, the overall mean score and the average score determined per animal, were used for evaluation.

 

6 rabbits were dermally exposed to 0.5 mL of C12.6 methacrylate (composition described above). Two application sites per animal were treated, one site was left intact, the other site was abraded. Test sites were covered with an occlusive dressing for 24 hours. Animals were observed for 72 hours. Irritation was scored by the method of Draize et al, 1959.

The treated abraded skin sites showed identical effects as the intact sites. For re-evaluation only the scores of the intact skin were used.

As the test was performed with 6 animals both, the CLP and DSD approaches for evaluation have to be conducted acc. Guidance on the application of the CLP criteria.

With the CLP approach the response of the individual animal values were averaged over the two observation times (24 hours and 72 hours after application) separately for erythema and edema. The mean erythema values were 1 for one animal, 1.5 for four animals and 2 for one animal. Erythema were not fully reversible within 72 hours. All mean sores were below 2.3.

With the DSD approach the average score overall animals was used separate for erythema and edema. The overall mean erythema score was 1.25 and the mean overall edema score 0.08. Both values are below 2.3.

In the third primary dermal irritation study 6 New Zealand White rabbits (strain: no data) were dermally exposed (intact and scarified skin) to 0.5 g octadecyl methacrylate for 72 hours. Animals then were observed for 3 days. Irritation was scored by the method of Draize et al, 1959.

The mean erythema score (average value of the single scores (animals 1-6; erythema; intact skin, 24h and 72h) was determined to be 0.083 out of 4 and, accordingly, the mean edema score 0.166 out of 4. Both values the overall mean erythema score and the mean overall edema score are below 2.3.

The results demonstrate that octadecyl methacrylate is not a dermal irritant.

6 rabbits were dermally exposed to 0.5 mL of C14.2 methacrylate (composition described above). Two application sites per animal were treated, one site was left intact, the other site was abraded. Test sites were covered with an occlusive dressing for 24 hours. Animals were observed for 72 hours. Irritation was scored by the method of Draize et al, 1959.

For re-evaluation only the sores of the intact skin were used. As the test was performed with 6 animals both, the CLP and DSD approaches for evaluation have to be conducted acc. to the guidance on the application of the CLP criteria.

With the CLP approach the response of the individual animal values were averaged over the two observation times (24 hours and 72 hours after application) separately for erythema and edema. The mean erythema values were 1 for two animals, 1.5 for one animal, 0.5 for one animal, 0 for one animal and 2 for one animal. Erythema were not fully reversible within 72 hours. All mean sores were below 2.3.

With the DSD approach the average score overall animals was used separate for erythema and edema. The overall mean erythema score was 1.00 and the mean overall edema score 0.33. Both values are below 2.3.

 

Performance of the study does not comply with requirements of the relevant recent EU and OECD guidelines, where semi-occlusive dressing, an exposure period of 4 hours, treatment of only intact skin and a recovery period of up to 14 days is stipulated. These studies are therefore of limited adequacy for C&L purposes due to intensity of the exposure regime and too short recovery period.

Isotridecyl methacrylate was tested in a primary dermal irritation study acc. to OECD 404. 3 New Zealand White rabbits were dermally exposed for 4 hours with 0.5 g undiluted test substance under semi-occlusive conditions. Animals were observed after 1h, 24h, 48h 72h and after 8 or 9 days. The test was re-evaluated acc. to CLP criteria. Mean erythema scores (24 +48 +72 h) were 0, 0.33 and 0.66 of max. 4. Mean edema scores (24 +48 +72 h) were 0, 1.33 and 1.66 of max. 4. All erythema scores were fully reversible within 72 h, all edema scores within 8 days. According to CLP criteria, isotridecyl methacrylate is not irritating to skin.

Human information

Human information is not available.

Summary and discussion of skin irritation

Due to the study design, the observation period of the study with C12.6 methacrylate and with C14.2 was too short to observe full recovery of the animals and also the duration of exposure was longer than the current guideline value. In analogy to isotridecyl methacrylate full recovery after 8 days is assumed.

Test results in rabbits are available for various esters covering long chain methacrylic acid esters dodecyl methacrylate to octadecyl methacrylate. There is slight irritating potential which is decreasing with growing chain length of the alcohol moiety.

In analogy octadecyl methacrylate is considered to be slightly irritating to skin but is not a skin irritant acc. to CLP criteria.

Comparison with criteria

In four studies with structurally related substances to octadecyl methacrylate the criteria for classification acc. to CLP and DSD were not fulfilled. Mean erythema and oedema scores were < 2.3 in all animals. As two studies duration were only 72 h, reversibility was demonstrated with the structurally related substance isotridecyl methacrylate which was fully reversible within 8 days.

Conclusions on classification and labelling

According to the test data available evaluated by DSD and CLP criteria, octadecyl methacrylate has not to be classified as irritating to skin. Consequently, the current classification should be deleted.

Eye irritation

 

Non human information

No study on the eye irritation potential is available for the single substance octadecyl methacrylate. The eye irritation was assessed in a weight of evidence approach with two available studies for structurally related long-chain alkyl methacrylates: One study according to Appraisal of the Safety of Chemicals in Foods, Drugs and Cosmetics, FDA Draize (1959) with methacrylic acid ester of an alcohol mixture with a mean C-number of 12,6, CAS: 90551-76-1 (65 % dodecyl methacrylate, 25 % tetradecyl methacrylate, 10 % higher alkyl methacrylates up to octadecyl methacrylate) and one study acc. OECD 405 with the structurally related substance isotridecyl methacrylate.

 

C12-methacrylate: In a study following an FDA guideline (Draize protocol) C12-methacrylate (0.1 ml) was instilled into the right eye of six New Zealand White rabbits. The lids were then gently held together for one second. The test eyes were not washed out following the instillation. The left eye remained untreated for control. The eyes were examined at 24, 48 and 72 hours from beginning of test. Eye irritation was scored for signs of corneal damage (density, area), iris reaction and lesions of the conjunctivae (erythema, chemosis and discharge). There were no signs of damage to cornea and iris and no signs of redness and chemosis of the conjunctiva. All irritation scores were 0.

 

Isotridecyl methacrylate was tested in a skin irritation study acc. OECD 405. 0.1 ml test substance was instilled into the right eye of 3 New Zealand White rabbits. The lids were then gently held together for one second. The test eyes were not washed out following the instillation. The left eye remained untreated for control. The examination of the cornea was secured with the aid of fluorescin after recording the observation at 24 hours. The grades of lesions at 24, 48 and 72 hours of the cornea, iris and conjunctiva were examined. There were no signs of damage to cornea and iris and no signs of redness and chemosis of the conjunctiva. All irritation scores were 0.

Human information

No data are available on human information     

 

Summary and discussion of eye irritation

No signs of eye irritation were found in two studies with structurally related long-chain alkyl methacrylates (C12.6 methacrylate and isotridecyl methacrylate). All irritation scores were 0 at all observation times (24, 48 and 72 hours). In analogy, octadecyl methacrylate is not considered to be an eye irritant.

Conclusions on classification and labelling

According to DSD and CLP criteria octadecyl methacrylate has not to be classified as irritating to eyes. Consequently, the current classification should be deleted.

Justification for selection of skin irritation / corrosion endpoint:
No single key study has been selected: instead, all available studies have been used in a weight-of-evidence approach.

Justification for selection of eye irritation endpoint:
No single key study has been selected: instead, all available studies have been used in a weight-of-evidence approach.

Effects on skin irritation/corrosion: slightly irritating

Justification for classification or non-classification

According to EU as well as UN-GHS criteria and CLP criteria no classification is warranted for the skin and eye irritation.