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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Description of key information

Accumulation in organisms is not to be expected.

Key value for chemical safety assessment

Additional information

For Pigment Black 32 (CAS 83524-75-8) no study on bioaccumulation is available. To assess the bioaccumulation potential of the test substance a weight of evidence approach using logPow and Critical body burden was conducted.

To draw conclusion of bioaccumulation data on log Pow was used. With a water solubility of <0.002 mg/L and a solubility of 0.040 mg/L in n-octanol, the log Pow can be estimated from the single solubilities as: Pow= C(n-octanol) / C(water)= 40 µg/L / <2 µg/L = >20, thus log Pow= >1.30.

Since the water solubility of <2µg/L was estimated below the limit of detection therefore it can be suggested that the water solubility of 1 µg/L is possibly the lowest measurable concentration and is used as worst-case for the estimation of the log Pow value. Pow= C(n-octanol) / C(water)= 40 µg/L / 1 µg/L = 40, thus log Pow= 1.6.

Therefore, bioaccumulation in organisms is not be expected.

To assess the bioaccumulation potential of a substance with low solubility in octanol and water the critical body burden (CBB) can be calculated based on the solubility in octanol. According to “Guidance on Information Requirements and Chemical Safety Assessment Chapter R.11: PBT/vPvB assessment” v 3.0 in R.11.4.2.1.2 octanol is a reasonable surrogate for fish lipid, thus a low substance concentration in octanol may indicate reduced bioconcentration / bioaccumulation potential. It is proposed that where a substance 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.

For Pigment Black 32 (CAS 83524-75-8) the CBB is estimated to be 1.26, based on Molecular mass of 630 g/Mol and Coctanol of 0.04 mg/L. Thus, the substance shows a Coctanol < CBB which indicates that the substance has only a limited potential to establish high body burdens and to bioaccumulate.