PARAMETER VALUES TO MODEL THE SOIL INGESTION PATHWAY

Soil ingestion is an important exposure pathway for contaminants that are not otherwise very mobile in the environment. Health of both human s and animals can be affected. This paper summarizes the literature an d recommends models and probabilistic parameter values for risk assess ment applications. Models of the pathway require estimates of the amou nts of soil ingested, the concentration of contaminants relative to th e original soil, and the bioavailability in the gut of the contaminant s ingested with soil. Using a lead-contaminated sandbox as an example, the modelling recommendations suggest that a child typically may cons ume 50 mg d(-1) of the sandbox soil, the soil ingested will have a ten fold higher lead concentration than the original soil, and the lead wi ll be as bioavailable as if ingested as inorganic lead in water.