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SOIL CADMIUM AS A THREAT TO HUMAN HEALTH
Citation:
Chaney, R. L., J A. Ryan*, Y. M. Li, AND S L. Brown. SOIL CADMIUM AS A THREAT TO HUMAN HEALTH. ISBN: 978-0-7923-584, Chapter 9, McLaughlin, M.J, and Singh, B.R. (ed.), Cadmium in Soils and Plants, Series: Development in Plant and Soil Sciences. Springer-Verlag, Berlin, Germany, 85:219-256, (1999).
Impact/Purpose:
to present information
Description:
Cd contamination of soils has been a public concern since the demonstration that soil Cd from Zn mine wastes which contaminated rice paddies had caused excessive Cd absorption and adverse health effects in members of subsistence farm families who consumed rice grown on the contaminated soils. This was the first observation of human Cd disease from soil Cd in the general environment, and scientists looked for potential adverse effects of soil Cd from their soils, agricultural practices, and dietary systems. This chapter considers available evidence about risk to humans of soil Cd, including food-chain transfer models, dietary factors and cultural factors which affect soil Cd risk. Further, fundamental aspects of how risk of ingested Cd to humans has been evaluated by many researchers is reviewed. The agronomic side of soil Cd risk has been carefully evluated in many countries, and although understanding can still be improved, models for soil Cd transfer to marketed crops are based on strong scientific knowledge. But information on Cd risk from dietary Cd appears to have little relationship with common Cd exposures from crops. Much research on adverse effects of food-chain Cd has ignored significant factors which affect the phytoavailability of soil Cd and the bioavailability of food Cd from crops grown on soils enriched by nearly all anthropogenic Cd contamination. We believe that failure to consider the difference beween Cd salts added to test diets, Cd in rice produced by subsistence farmers in Japan in 1970, and Cd in wheat or garden vegetables grown in western countries today, has caused great over estimation of the potential for adverse effects of soil Cd on humans. We are presenting this information within the historical context so that others may better see how this over-estimation of soil Cd transfer and risk at each step along the pathway to protect worst case or high-end exposures has constructed dietary Cd limits with many hidden safety factors. Because citizens express concern about environmental contamination in general, it is important that the extent of safety from soil Cd in most food systems be better understood and communicated.
