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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Not readily biodegradable (according to OECD criteria).

Key value for chemical safety assessment

Additional information

Data on the ready biodegradability of the described 'yellow disazo condensation pigment' are not available. However, for one yellow pigment (CAS 5280-80-8) the inherent biodegradability was investigated according to OECD guideline 302C (Solvias, 2000). Based on the measured oxygen consumption 12% degradation was observed after 28 days. Therefore the test item cannot be considered as inherently biodegradable. This result supports two model calculations which were conducted with EPI Suite v4.11 and CATALOGIC v5.12.1. The EPI Suite v4.11 (BIOWIN Program v4.10) calculation resulted in "not readily biodegradable" and the calculation with CATALOGIC v5.12.1 (BOD 28 days MITI (OECD 301C) v10.14) resulted in 8 % biodegradation after 28 d. The structural domain was correct with 85.11 % (14.89 % unknown) and the results, therefore, support the overall conclusion that the ‘yellow disazo condensation pigments’ are neither readily nor inherently biodegradable.

Moreover, the 'yellow disazo condensation pigment' is practically insoluble and therefore considered to be essentially not bioavailable. Due to the large molecular size, cellular uptake of the pigment is unlikely. Hence intracellular biodegradation, which is the main degradation route of bacteria, is probably low. It can be concluded that the substance is likely to persist in the environment. For this reason no ready degradation studies are proposed.