Propyloxirane

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

Justification for read-across to 1,2 -Butenoxide:

For the determination of the sensitizing potential of n-pentenoxide-1,2, a read-across was performed to 1,2-Butenoxide, another member of the epoxide family. The only structural difference between n-Pentenoxid-1,2 and 1,2-Butenoxide is the presence of an additional CH2 -group in n-Pentenoxide-1,2. The chemical characteristics between these two substances are quite similar, with 1,2 -Butenoxide being more soluble in water (86.6 g/L vs 23 g/L water solubility) and less lipophilic (log Pow=0.68 vs 1.29) and exhibiting a higher vapor pressure (227 hPa vs 70 hPa) as compared with n-Pentenoxide-1,2. It has been shown that the toxicities of epoxides decrease from ethylenoxide to propylenoxide to 1,2 -Butenoxide, suggesting that the toxicity of this reactive group of epoxide chemicals decreases with increasing length of the carbon backbone (Fox et al, 1983; NTP report No 267, 1985).

The sensitizing potential of 1,2 -Butenoxide was analyzed in the guinea pig maximization test similar to the method described by Maguire (1973). The test material was applied undiluted. Ten guinea pigs received 4 applications of the test material within 7 days during the insult phase of testing. An additional group of 10 guinea pigs received DER* 331 epoxy resin as a 10% solution in DOWANOL DPM/ Tween 80 ( 9: 1). The epoxy resin is known to be a skin sensitizer and served as a positive control. Each insult application consisted of 0.1 ml of the test material or the positive control resin applied to a gauze square patch, placed on the back of the guinea pig, then secured and covered with adhesive tape. The first insult application was allowed to remain in place for 48 hours, then removed, and a second application of 0.1 ml was made. At the time of the third application, a total of 0.2 ml of Freund's Adjuvant was injected intradermally adjacent to the insult site. Forty-eight hours after this application, the patch was removed and a fresh patch of 0.1 ml of the material was applied. The last patch was removed 48 hours later and the animals were allowed to rest for two weeks. Each time the insult patches were removed, observations for primary irritation effects were

recorded. After a two-week rest period, both flanks of the animal were clipped and challenged with the test solution on one side. The challenge applications were not covered. Skin response at these sites was recorded at 24 and 48 hours after application.

A positive response indicative of sensitization (slight to moderate redness) was observed on 9 of 10 guinea pigs receiving DER 331. However, none of the 10 guinea pigs treated with the undiluted test material revealed signs of sensitization. Therefore, this material was not considered a potential human skin sensitizer.

Migrated from Short description of key information:
not sensitizing (Dow Chemical Company, 1984)

Justification for selection of skin sensitisation endpoint:
Negative responses were obtained in the guinea pig maximization test with 1,2-Butylene oxide

Justification for classification or non-classification

According to the Directive 67/548/EEC and Regulation (EC) 1272/2008 (CLP), classification for sensitization of n-Pentenoxide-1,2 is not warranted.