This volume comprises the proceedings of a three-day meeting held at the Royal Society, London, UK on 22,23,24 April 1987. The combined second International Symposium on Geochemistry and Health and 5th European Meeting of the Society for Environmental Geochemistry and Health was sponsored by the International Association of Geochemistry and Cosmochemistry, UMESCO, the Society for Environmental Geochemistry and Health and Imperial College with additional finacial supposrt from the UK Department of the Environment, the Royal Society, London and the Southern California Edison Company.