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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

With a degradation of about 90 % within 28 days o-toluidine is considered as readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

The biodegradability of o-toluidine under the conditions described by the OECD TG 301A was tested by six different laboratories. All the laboratories followed the same procedure. Results were based on DOC analysis: all laboratories obtained ca. 90 % biodegradation after 28 days. In all cases the 10 d-window criterion was fulfilled.

Additionally the biodegradability of o-toluidine under the conditions according to the OECD TG 301E was tested by six different laboratories. Results were based on DOC analysis: five laboratories obtained > 90 % biodegradation, the other one reported a 67 % value after 28 days. Hence o-toluidine is considered as readily biodegradable. The 10 d-window criterion was fulfilled in either case.

Furthermore according to the national Japanese standard method comparable to the OECD TG 301 C guideline an aerobic ready test was performed. After a period of 28 days 65.4 % biodegradation was observed related to BOD.

With a test design comparable to Zahn-Wellens Test OECD TG 302B the inherent biodegradability was determined. o-Toluidine in a concentration of 200 mg/L COD was the sole source of carbon.

The degradation was 97.7 % after 5 days related to COD. Therefore the substance is considered as inherently biodegradable.

According to the OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test), the substance showed a degradation of 96 % within 11 days. Although 14 % elimination was caused by physical mechanisms the substance can be considered as inherently biodegradable.

Biodegradation of chemicals (including m-toluidine) was tested under anaerobic conditions in aquifer slurries from a sulfate reducing and a methanogenic site. o-Toluidine already disappeared about 27-35% in the sterile controls monitored over a 10 months period. Therefore, the reported data were corrected for this abiotic loss. o-Toluidine revealed no biotic transformation, neither under sulfate reducing nor under methanogenic conditions.