Model human digestive system for the determination of bioaccessibility of environmental pollutants.

This project will use a robust laboratory based model of the gastrointestinal tract to determine the bioacessibility (ability of a pollutant to be absorbed within the gut and interact with human cells) of environmental pollutants in the human gut. This will provide a major advance in accuracy of the risk assessment process undertaken by regulatory authorities to determine the toxicology of pollutants and their effects when ingested by humans. When accurate determinations of this parameter can be made, the soil guideline values (SGVs) provided by the Environment Agency in the regulatory guidance and for the assessment of contaminated land, will be significantly enhanced. Currently, no such repeatable determination protocol exists and guidance values are based upon intake, i.e. the amount of substance to which an individual is exposed rather than uptake, the amount of contaminant which enters the body and is taken up by the bloodstream. This proposal brings together two established gut models. The BGS model which mirrors behaviour in the stomach and small intestine and the University of Reading model which simulates the colon. The acidic conditions of the upper gut are believed to be the primary site of release of metals from the soil matrix, whereas the profuse microbial action of the colon may have more of an effect on organic pollutants. Both pollutant classes will be tested in the proposal. Unification of the two models will bring about the ability to mirror the whole human digestive tract. The proposal is supported by the Health Protection Agency who provide toxicological support to the Environment Agency when deriving SGVs. The HPA will support and advise on toxicological analyses conducted throughout this project.