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Skin sensitisation

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skin sensitisation: in vitro
Data waiving:
study technically not feasible
Justification for data waiving:
Justification for type of information:
2-BTP is highly volatile at room temperature and boils slightly below body temperature (e.g. 37°C, c.f. 2-BTP boiling temperature = 34.4°C; refer to dossier section 4.3 for details). Of the three key events in skin sensitisation described by REACH Annex VII Section 8.3.1, two of these events (specifically 8.3.1(b) inflammatory response in keratinocytes and 8.3.1(c) activation of dendritic cells) would be expected to be assessed by in-vitro studies:
EC test method B.60 (also OECD Test Guideline 442D), analysed by the KeratinoSens method involves a 48-hour incubation at 37°C; as the entire incubation step would take place above the boiling temperature of the test material it is highly likely that the test material would predominantly evaporate or otherwise volatilise out of solution and as such the study is not technically feasible.
Analysis of Activation of Dendritic cells as described in OECD Test Guideline 442E similarly describes a number of in-vitro tests, all of which involve incubation of the test substance at 37°C; for the reason described above these tests would similarly not be technically feasible.

It is noted that the in-chemico assessment of Molecular Interaction with Proteins (EC method B.59) is conducted typically at room temperature (c.a. 21°C) and it may be technically possible to conduct this study on 2-BTP. On the basis that at least two out of the three key events listed under Annex VII Section 8.3.1 must be assessed to be positive before a conclusion about Skin Sensitisation may be drawn, this assessment would not provide sufficient information in isolation from the other assessment of key events, and is therefore considered not to be scientifically justified.

According to REACH Annex XI Section 2, in-vitro testing for Skin Sensitisation is waived on the basis that testing is not technically possible.

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