Lessons from case studies of metals: investigating exposure, bioavailability, and risk.

Since metals are widely distributed in environmental matrices, humans are exposed to them by either anthropogenic activities or inadvertently by necessity. Selected metals: arsenic, mercury, iron, tin, lead and chromium were chosen on the basis of their economic and public health importance to illustrate the diversity of exposure pathways and differences in factors governing bioavailability. Bioavailability is central to the toxicity of metals and this is discussed from the health risk paradigm standpoint of risk assessment and risk management and the impacts of including or excluding bioavailability in such assessment. The lessons from the case studies of arsenic, mercury, tin and chromium provide a unified concept of methods that can be used in investigating and controlling outbreaks due to metal poisoning in other similar situations.