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As there is no data available for o-toluidine, read across with p-toluidine (CAS No. 106-49-0) is proposed to cover this endpoint. o-Toluidine and p-toluidine are isomers and have very similar chemical structures. Their main physico-chemical parameters (vapour pressure, water solubility, octanol/water partition coefficient, organic carbon partition coefficient and dissociation constant) are in the same range. The main ecotoxicological parameters like short-term toxicity on Daphnia and fish, toxicity on algae, and long-term toxicity on Daphnia are also in the same order of magnitude. It is shown that Daphnia is the most sensitive aquatic organism for both isomers. Therefore a read across between these two substances to cover physico-chemical and ecotoxicological endpoints for o-toluidine seems to be justified. More details regarding the read across justification are depicted in the annex of the Chemical Safety Report (CSR). Regarding the experimentally determined BCF of < 13 for p-toluidine, the substance has a very low potential for bioaccumulation.

An experimentally determined logKow of 1.4 for o-toluidine supports this consideration that the substance has a low potential for bioaccumulation.

Additionally experimental bioconcentration factors (BCF) for o-toluidine indicate no significant potential for bioaccumulation in Pacific oysters (Crassostrea gigas) or Common bay mussels (Mytilus edulis). The obtained BCF values were 4.2 and 4.6 for mussels and oyster, respectively.