methyl acrylate; methyl propenoate

Endpoint summary

Description of key information

Skin contact with methyl acrylate causes irritation.

Methyl acrylate may be irritating to the respiratory system and may cause serious irritation to the eyes.

Key value for chemical safety assessment

Skin irritation / corrosion

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Eye irritation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Additional information

Skin irritation:

Undiluted methyl acrylate was highly irritating to the skin of rabbits, when applied for 1 or 4 hours under semiocclusive conditions. After 1- and 4-hours exposures, slight to well-defined erythema (grades 1 and 2 of the Draize scoring system) and slight edema (grade 1) were still present in some animals at the end of the observation period at day 7. 4 of 6 animals showed scaling or severe scaling at the end of the observation period. Mean erythema and edema scores (24-72 hours) were 2.17 and 2.44, respectively, after 4-hour exposure. Erythema and edema were most severe at 1 hour postexposure (grades 2 and 3) and slowly decreased in intensity during the following days. One animal (out of 6 tested) showed superficial necrosis after exposure for 1 hour (BASF AG 1982).

This test was repeated under occlusive conditions, i.e. over-predictive conditions, with more severe results (BASF AG 1982). Mean scores for erythema and edema (24-72 hours) were 3.56 and 3.72, respectively. At the end of the 7-day observation period, 2 of 6 animals showed a full thickness necrosis, the other 4 animals showed superficial necrosis.

Several other tests, all under occlusive conditions, confirmed the presented results (BASF AG 1978, BASF AG 1979, Potokar et al. 1985).

Methyl acrylate proved to be highly irritating to the skin of rabbits, when applied for 4 hrs using semi-occlusive conditions in a study similar to OECD TG 404. No full-thickness skin destruction was observed under these conditions which are relevant for classification according to 67/548/EEC and GHS (EU and UN), respectively. Thus, methyl acrylate was assessed to be irritating to the skin.

Eye irritation:

Information on the eye irritation potential of methyl acrylate is based upon the weight of evidence from available studies.

Undiluted methyl acrylate (0.1 mL) was instilled into the eye of one rabbit and caused corneal damage, slight iritis and severe lesions of the conjunctivae. After 7 days the cornea showed moderate to severe opacity with no details of the iris visible. In addition, slight iritis and moderate to severe lesions of the conjunctivae were noticeable. Mean scores for cornea, iris, conjunctivae and chemosis (24-72 hours) were 2.33, 1, 2, and 3, respectively (BASF AG 1978). The authors considered methyl acrylate as severely irritating to the eyes, however thesestudy results do not fulfill the CLP requirements for a Cat 1 as a stand-alone study since the observation period was only 7 days and the corneal opacity and iritis scores did not support a cat 1 classification. Specifically:

·        The study was conducted on 1 rabbit and the observation period was 7 days, not 21 as indicated as the “normal” period of observation. If the study were carried out to 21 days of observation it is expected that full reversal of irritation would occur based upon the below additional studies. A category 1 classification is not supported.

·        The study was conducted on only 1 rabbit, not 3. Also, the mean 24, 48 and 72 hr scores for corneal opacity and iritis were 2.33 and 1 respectively. These scores also do not support a category 1 classification.

Additional weight of evidence that supports an eye irritation Category 2 classification for methyl acrylate includes a recently finalized Bovine Corneal Opacity and Permeability Test (BCOP) study (Reliability 1) that is compliant with OECD 437 (BAMM, 2017). This study showed conclusively that methyl acrylate was not corrosive. According to the EURL ECVAM DB-ALM Protocol 127 Classification, the substance would be considered a Mild Eye Irritant. 

Older rabbit eye irritation studies using undiluted methyl acrylate are also available that support classification of this substance a Cat 2 eye irritant as with these studies showing reversibility of the irritation within 7 days (Wolf, 1957; BASF, 1958).

Upon assessment of TNO, 1978 against the GHS criteria and consideration of all available eye irritation study information the weight of evidence indicates that Methyl acrylate should be classified as a Cat 2 eye irritant.

Based on the presented data, methyl acrylate may cause serious eye irritation.

Respiratory irritation:

There exists no standard test method for the assessment of respiratory irritation. Thus, the labelling of MA with "R 37, Irritating to respiratory tract" according to current EU regulations is not based on results of a specific respiratory irritation test, but on considerations on the general irritation potential of MA. There is evidence that methyl acrylate vapours were irritating to the eyes and respiratory tract of rats and mice (BASF AG 1979). In addition, Silver et al. (1981) confirmed the respiratory irritancy of methyl acrylate by measuring its effect on the respiratory frequency, tidal volume, minute ventilation, and rectal temperature as indices for irritancy.

Thus, labelling with R 37 is confirmed on the basis of all of the respective data mentioned in this IUCLID5 -Registration Dossier.

Justification for classification or non-classification

EU classification according to Regulation (EC) No. 1272/2008:

- Skin corrosion/irritation: Category 2

- Serious eye damage/eye irritation: Category 1

- Specific target organ toxicity, Single exposure: Category 3 (May cause respiratory irritation)