Use of Bioaccessibility Assays for Lead Exposure Assessment

摘要

There is worldwide concern regarding the presence of elevated lead (Pb) in the envi- ronment due to the potential health effects resulting from Pb exposure. Extensive research has verified that Pb exposure enhances blood Pb levels in young children and this may result in impaired cognitive and behavioural development. For young children, incidental ingestion of soil and dust, via hand-to-mouth activity, is considered an impor- tant pathway for Pb exposure. However, the Pb dose that is absorbed into systemic circu- lation (the bioavailable fraction) may vary depending on the form and solubility of Pb present, the physico-chemical properties of the ingested material as well as the child’s nutritional status1. In vivo assays have been developed for assessing Pb bioavailability in relation to human receptors (absorption after ingestion of contaminated soil), however, due to the time and expense required to perform in vivo studies, bioavailability testing is usually not practical. As a result, in vitro assays simulating human gastrointestinal condi- tions have been developed. Currently, a number of methods are available for the assess- ment of Pb bioaccessibility in contaminated soils. However, methods that use only gastric phase extraction (e.g. SBET) may over-predict the dose of Pb that may be absorbed while the inclusion of an intestinal extraction following the gastric phase (e.g. PBET) may under-predict Pb bioavailability compared to in vivo assays. In this study, Pb bioaccessi- bility was assessed in contaminated soils and compared to spiked references doses in order to determine the impact of intestinal pH on relative Pb bioaccessibility following dissolution of Pb in the gastric phase.