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This research project is a literature review of the fate of chlorinated solvents released into soil, and their potential to transfer to the food chain.
Study Duration : January 2002 to July 2002
Historically, toxic chlorinated solvents have sometimes been disposed of in drum graves, unlined landfill sites, or evaporation lagoons. Accidental spillages and leaks have also resulted in chlorinated solvents being released to land. Chlorinated aliphatic and aromatic hydrocarbons often tend to be persistent once they enter soil or the underlying bedrock and groundwater. Consequently, crops and livestock raised close to sites where chlorinated solvents have been released could become exposed to these contaminants. This project will provide a literature review of the potential for short chain chlorinated aliphatic hydrocarbons and chlorinated benzenes to accumulate in the terrestrial food chain.
The literature review will focus on trichloroethane, trichloroethene, tetrachloroethene, hexachlorobutadiene, chlorinated propenes and chlorinated benzenes. However, relevant information about other chlorinated solvents will also be included in the report if they are identified as significant contaminants of either the waste disposal sites or the environment. Initially, published information on the physicochemical properties, the patterns of use and the environmental fate of each of these chlorinated hydrocarbons will be collated. Information on the transfer and uptake mechanisms and the bioavailability of chlorinated solvents by crops and livestock will also be collated and the potential for any of the contaminants to persist and bioaccumulate in biota will be reviewed. Finally, various approaches that could be considered for modelling the movement of these waste solvents through the environment and into the food chain will be reviewed.
This project was designed to review the potential for waste solvents at contaminated sites to enter the food chain and to provide a summary of available information regarding the persistence, migration and uptake by crops or livestock of chlorinated solvents.
The findings from the literature review indicated a relatively poor persistence of the low molecular weight chlorinated aliphatic hydrocarbons in biota, meaning that there would be little potential for widespread contamination of the food chain. This is reassuring and reinforces the Agency's existing view that these chemicals do not generally pose a threat to the safety of food produced close to former disposal sites for these chemicals. The literature review also confirmed the Agency's existing knowledge that the more highly chlorinated chlorobenzenes, which are no longer commercially produced or used, are more persistent and are therefore more likely to accumulate in the food chain.
The findings of this literature review will not significantly affect the Agency's policy concerning chlorinated solvents in the environment but they do justify the Agency's focus on semi-volatile persistent organic pollutants rather than the lighter more volatile chlorinated solvents. However, risk assessments will still be justified in cases involving severe environmental contamination due to chlorinated solvents.
Final report is available from the FSA Library and Information centre.
To obtain a copy, please contact the Enquiry Desk, Dr Elsie Widdowson Library and Information Services, Food Standards Agency ( Tel: 020 7276 8181/8182 or e-mail:
library&info@foodstandards.gsi.gov.uk
)
Contact
: For any enquiries concerning this research project, please contact the relevant Programme contact or e-mail:
science@foodstandards.gsi.gov.uk
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