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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Description of key information

With a BCF of < 1.3 at 100 µg/L and < 13 at 10 µg/L the substance has a very low potential for bioaccumulation.

Key value for chemical safety assessment

BCF (aquatic species):
13 dimensionless

Additional information

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 range. 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).

According to a guideline which corresponds to OECD Guideline 305C (Bioaccumulation: Test for the degree of bioconcentration in Fish), a BCF of < 1.3 at 100 µg/L and < 13 at 10 µg/L was determined on fish (Cyprinus carpio) for p-toluidine. The test was conducted by EA, Japan: "Investigation of the Ecotoxicological Effects of OECD High Production Volume Chemicals", Office of Health Studies, Environmental Health Department, Environment Agency, Japan.

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). Oysters and mussels were exposed to 5 mg/L of o-toluidine in seawater for 24 hours, at 15 °C and pH 7.9. o-Toluidine carbon was 14C-ring-labelled, 3 replicates were conducted.

The steady state of the body burden was reached after 2 - 4 hours of exposure for the oysters and 4 hours for the mussels.

The obtained BCF values were 4.2 and 4.6 for mussels and oyster, respectively.

Supplemental the Kow value of 1.4 for o-toluidine indicates a low potential for bioaccumulation.