Registration Dossier
Registration Dossier
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EC number: 247-975-0 | CAS number: 26760-64-5
Endpoint summary
Administrative data
Description of key information
Based on assessment of the available data for 2-methyl-2-butene (2M2B), isoamylene should be considered as mildly irritating to skin and non-irritating to eyes. The respiratory tract irritation potential of isoamylene is not known, as no data are available for this endpoint.
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 adverse effect observed (not irritating)
Additional information
Skin Irritation
Studies in Animals
An occlusive patch test based on the method of Draize (1975) was used to assess the primary skin irritation induced by 2M2B applied neat. The mean erythema and oedema scores for abraded and non-abraded skin were 0.8 and 0.6 i.e. <2 and <1 respectively. The primary irritation score calculated according to the method of Draize was 1.79.
On this basis 2M2B may be regarded as being mildly irritating to rabbit skin. The erythema and oedema scores at 7 days were higher than those at 72 hours but at 7 days all the skin patches were beginning to dry out and flake. It is possible the animals scratching these areas was a contributory factor, resulting in the slightly higher erythema scores (SRC, 1980).
Studies in Humans
No data available
Eye Irritation
Studies in Animals
The method of Draize (1963) was used to assess the eye irritancy of 2M2B in New Zealand White rabbits. Instillation of 2M2B into the eye resulted in a moderate initial pain response (grade 4) in all animals. Mean total scores for the responses of the conjunctiva, cornea and iris were 0.5, 0 and 0 (i.e. all ≤0.5) and based on these results, isoamylene should be considered as non-irritating to rabbit eyes (SRC, 1980).
Studies in Humans
No data available
Respiratory Tract Irritation
No studies on respiratory tract irritation have been conducted with isoamylene. From the acute inhalation study and repeat dose study (HLS, 2003) there is no specific evidence of acute irritation effects warranting classification.
Effects on skin irritation/corrosion: slightly irritating
Justification for classification or non-classification
Based on assessment of the available data for 2M2B, isoamylene does not warrant classification as a respiratory tract or eye irritant under DSD or CLP.
For skin irritation, all responses were below the threshold scores for classification however on the basis of criteria that inflammation of the skin is also significant if it persists in at least two animals (implied of 3, i.e. 4 of 6) at the end of the observation time, classificaton Xi, R38 Irritating to skin is warranted under DSD and category 2 H315 causes skin Irritation under CLP.
There is no evidence of irritation to the respiratory tract and no classification is warranted.
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