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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

CTC is rapidly biodegradable under anaerobic conditions and may biodegrade under aerobic conditions at non toxic concentrations (at or below 10 mg/L).

Key value for chemical safety assessment

Biodegradation in water:
inherently biodegradable, fulfilling specific criteria

Additional information

Several articles report a rapid biodegradation of carbon tetrachloride under anaerobic conditions, in denitrifying as well as in methanogenic conditions. These investigations revealed evidence that not only dehalogenation to transient chloroform but also complete mineralisation to CO2.

 

Under aerobic conditions, Tabak at al., in 1981, have observed a rapid disappearance in conditions were volatilisation is under control. It can be concluded to a rapid primary biodegradation. The only other study that has been carried out under aerobic conditions is reported by Japanese Authorities on the CERI website. No ultimate biodegradation has been observed, few information is available on the study, but the tested concentration of 100 mg/L (in accordance to MITI(I) / OECD 301C guideline) may have biased the result, being in a toxic range. In the absence of results of a test made in accordance to OECD guidelines at lower concentrations, ready biodegradability of carbon tetrachloride cannot be assumed.

 

A detailed review of the biodegradability of chlorinated aliphatic compounds has been done by J.A. Field and R. Sierra-Alvarez from University of Arizona and has been published by EuroChlor in 2004. With respect to CTC, this review reports several observations made under real environmental conditions such as landfills and in bioreactors. It is concluded that CTC is almost completely biodegraded under anaerobic conditions by co-metabolism.