2-methylimidazole

Endpoint summary

Description of key information

2-Methylimidazole was found to be corrosive to the rabbit skin under occlusive conditions.

A single application of undiluted 2-methylimidazole to the rabbit eye caused cauterization of the mucous membranes.

Key value for chemical safety assessment

Skin irritation / corrosion

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (corrosive)

Eye irritation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irreversible damage)

Additional information

Skin irritation

2-Methylimidazole was applied to the skin of Vienna White rabbits in a study comparable to OECD guideline 404 for 4 h (using 6 animals) under occlusive conditions and observations were made 1 hour, 24 and 48 hours and 8 days after treatment (BASF AG, 1980, 4 h exposure). The mean erythema score (24 and 48 hours) was 2.2. This effect was not reversible in three animals after 8 days; in two of these animals necrosis was observed (and an erythema score of 4), in the other animal desquamation, spotted necrotic tissue and an erythema score of 2 was observed. The mean edema score (24 and 48 hours) was 1.2 and edema was fully reversible within 8 days. 2-Methylimidazol was judged to be corrosive to the skin.

In a supporting study 2-methylimidazole was applied to the skin of Vienna White rabbits in a study comparable to OECD guideline 404 for 1 h (using 6 animals) under occlusive conditions and observations were made 4, 24 and 48 hours and 8 days after treatment (BASF AG, 1980, 1 h exposure). The mean erythema score (24 and 48 hours) was 1.1. Erythema was fully reversible in 5 out of 6 animals after 8 days (for two animals desquamation was observed); necrosis was observed in the other animal after 8 days. The mean edema score (24 and 48 hours) was 0.4 and edema was fully reversible within 8 days. After 8 days edema was observed in 1 animal (score 1).

In another supporting study 2-methylimidazole was applied to the skin of Vienna White rabbits in a study comparable to OECD guideline 404 for 1, 5 and 15 min and 20 h (using 2 animals at all exposure durations) under occlusive conditions and observed for 8 days (BASF AG, 1966). No irritation (edema and erythema) was observed after 1, 5 and 15 min of exposure. Exposure for 20 hours caused edema and erythema scores of 3 (24 hours after treatment). Slight necrosis with marked edema and erythema at the edge of the patch tested and strong necrosis was observed 8 days after treatment and at that observation point the surroundings showed marked desquamation.

 

In an in vitro study, 2-methylimidazole was tested using the EpiDermTM Skin Corrosion Test (BASF AG, 2002). The test consists of a topical exposure of the test substance to the surface of a human reconstituted epidermis model for 3 minutes and 1 hour followed by a cell viability test. Cell viability is measured by dehydrogenase conversion of the yellow, water-soluble MTT (3-[4,5- dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide), present in cell mitochondria, into a blue formazan salt that is measured quantitatively after isopropanol – extraction from the tissues. The optical density of the extracts of test substance treated tissues is compared to negative control values from tissue treated with highly de-ionized water and is expressed as relative tissue viability. Based on the results of this study (viability scores as % of negative control were 78% and 15% for 3 minutes and 1 hour exposure, respectively) and applying the evaluation criteria it is concluded that 2-methylimidazole does not have a corrosive potential. The results of the in vitro study are not in general contrary to the in vivo results, as the viablilty value after 1 hour exposure exactly meets the threshold value (15% viability after 1 hour expposure). Overall it is concluded, that the results of the in vivo studies outweight the results of the in vitro study.

Eye irritation

2-Methylimidazole was applied to the conjunctival sac of the eyes of 2 Vienna White rabbits in a study comparable to OECD guideline 405 (BASF AG, 1966). Animals were observed after 1 hour, 24 hours and 8 days after the treatment. The application caused cauterization of the eyes. 2-Methylimidazole was judged corrosive to the eyes.

Justification for classification or non-classification

Based on the available in vivo data, 2-methylimidazole needs to be classified as corrosive to the skin and eyes according to the Regulation (EC) No. 1272/2008: Skin Corr. Cat. 1C, H314 and Eye Dam. Cat. 1; H318 .