HDI oligomers, oxadiazintrione

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

For an assessment of skin sensitisation two in vivo studies are available: a Buehler and a Guinea Pig Maximation test (GPMT). Both studies are conducted according to OECD TG 406.

In the GPMT 20 test and 10 control animals were induced intradermally with a 1 % test substance formulation (vehicle acetone/peanut oil) and, with a one week interval, epicutaneously with undiluted test substance. Animals of the control groups received the treatment without the addition of test substance (the amount of test substance was replaced by the vehicle). For challenge the test substance was applied epicutaneously at a 25 % concentration, and a further re-challenge used a 3 % concentration of the test substance.

48 hours after challenge 16/20 animals of the test group showed a positive skin reaction on the test substance -treated flanks. The re-challenge at 3 % confirmed the positive reaction (18/20). Only one positive skin reaction (1/10) occurred in the control group treated with a 25 % concentration, none occurred in the control group at 3 %.

In the Buehler test 12 test and 12 control animals were topically induced thrice with a 100 % test substance formulation (vehicle acetone) at a 7 days-interval. Animals of the control groups received the treatment without the addition of test substance (the amount of test substance was replaced by the vehicle). For challenge the test substance was applied epicutaneously at a 100 and 10 % concentration, a second challenge used concentrations of 50 and 25 %.

At challenge all animals of the test group and 4/12 animals of the control group showed a positive skin reaction to the undiluted test substance. At the 10 % test substance concentration none of the animals reacted. In the second challenge none of the animals reacted to the 50 or 25 % concentration, except one animal showing a positive skin reaction at 50 %.

Based on the studies, it was concluded that the substance has a potential for skin sensitisation.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information:

No animal study investigating the respiratory sensitisation potential is available for the substance.

Diisocyanates in general are known respiratory sensitizers in humans. For 3,5-bis(6-isocyanatohexyl)-1,3,5-oxadiazinane-2,4,6-trione in particular no respective human data are available.

Justification for classification or non-classification

According to Regulation (EC) No 1272/2008, Annex I, classification as skin sensitising is warranted.

Regulation (EU) No 286/2011 amending Regulation (EC) No 1272/2008 stipulates that, in case data are sufficient, an allocation of skin sensitizers into sub-category 1A (strong sensitizers) or sub-category 1B (other skin sensitizers) shall be performed. Where data are not sufficient a classification as Skin Sensitisation Category 1 without sub-categorisation results.

HDI derived homopolymers (Hexane, 1,6-diisocyanato-, homopolymer; CAS no 28182 -81 -2) are other oligomerisation products of 1,6-hexamethylene diisocyanate monomer. They were considered to have a similar skin sensitisation potential like HDI oligomers, oxadiazintrione type based on structural analogy (all contain isocyanate groups attached via aliphatic chains to an urethane-group containing core), similar physico-chemical properties (vapour pressure, viscosity, reactive with nucleophiles and thus hydrolytically unstable) and on the results of in vivo skin sensitisation assays. For all of these HDI derived homopolymers allocation to Skin Sensitisation Category 1 without sub-categorisation was decided, since a solid assessment on potency was not possible based on the available data (see ECHA registered substances EC 931 -274 -8, 931-297-3, 939-340-8, 939-657-1, 931-288-4). Due to the similarities described above and reasons of consistency HDI oligomers, oxadiazintrione type should also be allocated to Skin Sensitisation Category 1 without sub-categorisation.

For risk assessment substances with Skin Sens. Cat. 1 have to be allocated to the high hazard band (ECHAGuidance on information requirements and chemical safety assessment, Part E, Nov. 2012).