Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: May 10, 2004
Publication Date: October 31, 2004
Citation: Chaney, R.L. 2004. Cadmium in fertilizers: risks to food-chain? [abstract]. American Society of Agronomy. p. 3673. Technical Abstract: Phosphate ores contain geogenic Cd; Cd levels vary widely in ores from different locations. Some volcanic P ores are very low (less than 5 mg/kg)while some sedimentary phosphates are higher than 400 ppm Cd. Removal of Cd during manufacturing is expensive. Risks from Cd in P-fertilizers has been studied for many years; long term use of higher Cd phosphates on strongly acidic soils increased crop Cd (e.g., island phosphates in Australia). But transfer of Cd risk to consumers is complex; no adverse effects of phosphate fertilizers have been observed. To date, only subsistence rice farmers who consumed locally grown polished rice grown on paddy soil contaminated by Zn-Pb mine wastes have experienced adverse human health effects of dietary Cd. Malnutrition induced by subsistence rice diets played an important role in Cd absorption and risk. Zn and Fe are excluded from rice grain, and deficiency of Fe and Zn promote Cd absorption in the intestine. The complexity of estimating required limits for Cd or other trace elements in fertilizer products has made setting limits difficult, but monitoring of these trace elements is needed to protect long term soil fertility. State fertilizer regulatory officials have begun to check fertilizers for contaminants and some States have set limits. Such limits are important in excluding from sale adulterated products such as an imported byproduct Zn sulfate which contained about as much Cd as Zn.