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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

under test conditions no biodegradation observed

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

The substance has been tested with screening evaluation test according to the internal method DEV H4 and H5, and inherent biodegradadation according to the Ciba Geigy AG internal method 12 (similar to OECD 302B). The purity of substance is around 75 %.

COD/BOD5 ratio

The first test measures the Biochemical Oxygen Demand (BOD) and the Chemical Oxygen Demand (COD).

Biochemical Oxygen Demand or BOD is the amount of dissolved oxygen needed by aerobic biological organisms in a body of water to break down organic material present in a given water sample at certain temperature over a specific time period. The term also refers to a chemical procedure for determining this amount. This is not a precise quantitative test, although it is widely used as an indication of the organic quality of water, therefore is not be used as quantitative date about ready biodegradation.

As reported in ECHA Guidance R.7b: "The BOD5 test is a traditional biodegradation test that is now replaced by the ready biodegradability tests. Therefore, this test should not be performed today for assessment of the ready biodegradability of substances. Older test data may, however, be used when no other degradability data are available."

The main data available is the measure of BOD5, COD , their ratio. According to the ECHA "Guidance on information requirements and chemical safety assessment - Chapter R.7b: Endpoint specific guidance" (May 2008 version 1.1), if the BOD5:COD ratio is lower than 0.5, it can be expected that the substance is not readily biodegradable; if the ratio between BOD5 and COD is more than 0.5 there is an indication of ready biodegradation, but it is not our case. The value of BOD5/COD is zero, therefore it can be concluded that the substance is expected as not readily biodegradable.

Inherent biodegradation

This evaluation is supported by an inherent biodegradation study performed in 1974 according to the Ciba Geigy AG internal method 12. After 31 days of test period, no biodegradation has been noted.

It was confirmed that the substance is not biodegradable.