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Environmental fate & pathways

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Biotic degradation

No significant biodegradation of chloroform in surface waters was observed under aerobic, environmental conditions (Bouwer et al. 1981, MITI 1992). The biodegradation reported by Tabak and co-workers is not taken into consideration because of the methodological flaws in their test system. Chloroform in water was only degraded under anaerobic conditions in specifically constructed bio-reactors (Bouwer et al. 1981).

Chloroform is degraded in anaerobic sediments (van Beelen and van Keulen 1990, van Beelen and van Vlardingen 1993). The half-lives observed in tests carried out with natural methanogenic sediments and in accordance with principles similar to those of OECD Guideline No. 308 ranged from 2 to 37 days, and realistic values were around 15 days. Similar tests with sandy sediments exhibiting low contents of organic carbon showed that no degradation of chloroform was achieved, which was not due to the absence of methanogenic bacteria but due to the conditions present in this type of sediment.

Degradation tests performed with soils indicated that chloroform is only degraded by certain methane-utilising bacteria under special aerobic conditions. In general, it was assumed that no significant biodegradation of chloroform occurred in soils (France 2007).