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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Key value for chemical safety assessment

Biodegradation in water:
inherently biodegradable

Additional information

The Ready Biodegradability of Precyclemone B has been determined in two ready biodegradability tests (Givaudan 14 -E067 and 14 -E153). Both are GLP studies, performed according to international accepted guidelines and using the Manometric Respirometry Test conditions (OECD 301F). The level of biodegradation achieved after 28 days was 38% and 41% respectively, which is insufficient to classify the substance as readily biodegradable.

The test concentrations employed in the two studies were 30mg/L and 17mg/L respectively, which are significantly higher than the water solubility of Precyclemone B which is only 3.19 mg/L. This means that the biodegradation rate will be controlled by the dissolution rate. This is indicated in the biodegradation curves which show a gradual increase in the percentage of biodegradation. Since a plateau was not reached in either study by day 28, the tests were extended. The biodegradation continued and reached a level of 58-61% after 68 -70 days in the test conducted at 30mg/L (Givaudan 14-E067) and 60 -70% after 60 -70 days at the lower test item concentration of 17mg/L (Givaudan 14 -E153). Based on these results, Precyclemone B is considered to be inherently and ultimately biodegradable. Given that a level of >60% biodegradation was achieved indicates that the substance is not expected to be persistent in the environment.