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Environmental fate & pathways

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On the basis of the measured solubility in n-octanol and water, the partitioning coefficient of the described 'red disazo condensation pigment' was estimated to be below three. In accordance with Annex IX of Regulation (EC) No. 1907/2006, the study on bioaccumulation does not need to be conducted if the substance has a low potential for bioaccumulation (e.g. logKow < 3).

Another indicator for low bioaccumulation is the low octanol solubility compared to the critical body burden (see ECHA Guidance on information requirements and chemical safety assessment; Chapter R.11: PBT Assessment). If the solubility of a substance in octanol is so low that the maximum concentration levels that can be attained in organisms do not reach levels sufficient to elicit any toxic effects, it can be reasoned that such accumulation would not be of concern. The concentration of a substance at which the occurrence of toxic effects normally can be excluded is 0.002 mmol/l in n-octanol. As octanol is a reasonable surrogate for fish lipid, a low substance concentration in octanol may indicate reduced bioconcentration / bioaccumulation potential. The concept is based on available measurements for substances with narcotic mode of action using a safety factor of 10 for the uncertainty of the available CBB measurements. It is proposed that where a chemical shows no specific mode of action and has a Coctanol [mg/L] < 0.002 [mMol/L] x Mol weight [g/Mol] it can be assumed that the compound has only a limited potential to establish high body burdens and to bioaccumulate. If it does bioaccumulate, it would be unlikely to rise to levels in biota that would cause significant effects.

Therefore, if the octanol solubility is below the CBB, the maximum uptake of the substance can be expected to be below the CBB and toxicity is not likely.

For CAS 3905 -19 -9 the solubility in octanol was measured to be < 0.0065 mg/L and is well below the estimated CBB of 1.56 mg/L. Furthermore the pigment is practically insoluble in water and therefore considered to be essentially not bioavailable. Due to the large molecular size of above 700 g/Mol (794.468 g/Mol) and the average maximum diameter (Dmaxaver) of 2.38 nm cellular uptake of the pigment is unlikely.

Therefore, data on bioaccumulation are not provided.