4-chloro-o-xylene

Biodegradation in water: screening tests

Description of key information

1 % biodegradation, not fulfilling criteria of being readily biodegradable (non-adapted activated sludge); OECD 301D (Boeri, 2004)

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

In the key study, a ready biodegradability test was carried out in accordance with the OECD 301D Ready Biodegradability closed bottle test guideline under GLP conditions.

The test was performed with a single concentration of test material, 5.0 mg/L. The chemical oxygen demand for the sample of the test material was 106.5 % (1.065 mg O₂/mg test material). A series of 10 replicate test vessels was established for the test concentration, an inoculum blank, a medium blank, and a positive control (2 mg/L sodium benzoate). The dissolved oxygen concentration in duplicate test vessels from each series was measured at the start of the test. The remaining test vessels were maintained in the dark at 20 ± 1 °C for up to 28 days. Duplicate BOD bottles from each series were removed on days 5, 14, 21, and 28, and the dissolved oxygen concentration was measured.

The average biodegradation for duplicate test flasks at 28 days for the test material was 1 %. The positive control yielded 63 % of the theoretical degradation at the end of the test, demonstrating the adequacy of the inoculum. The test material did not satisfy the test criteria for ready biodegradability (60 % degradability within 28 days).