Australia Cuts Cadmium in Food.

In many ways it makes sense to recycle sludge from sewage treatment plants into fertilizer; it's cheaper than dumping at sea, and it helps crops. But sewage sludge can pick up agricultural, roadway, and industrial contaminants via runoff--contaminants such as cadmium, which can cause major human health problems when it enters the food chain through plants grown in soil treated with the fertilizer. Cadmium bioaccumulates in the liver, kidneys, and bone, where it can cause effects such as renal dysfunction, kidney stones, weakened bones, and cancer. Because cadmium concentrations in Australian soils are growing, the government has taken the proactive step of launching the National Cadmium Minimisation Strategy for Agriculture.

Although cadmium occurs naturally in the environment, its accumulation in soils and plants has been exacerbated by human activities, chiefly the application of cadmium-contaminated phosphate fertilizers, certain animal manures, sewage effluents, sewage sludge, and composted biosolids. Cadmium, like other metals, binds strongly to soil particles and persists indefinitely in the environment.

Various guidelines throughout Australia govern cadmium concentrations in fertilizers, sewage sludge, water, and soil. The aim of the national strategy is to integrate the efforts of all sectors into a coordinated framework of best practices and guidelines. The strategy comprises four key elements designed to minimize the addition of cadmium to soils in areas with a potential or existing cadmium problem. The elements include good farming practices, proper fertilizer labeling, use of low-cadmium fertilizers in high-risk areas, and tighter regulations for cadmium concentrations in soil. A committee representing the state governments, the commonwealth, farmers, the fertilizer industry, and academia is pursuing the development of these practices and principles to implement the strategy.

The strategy will be funded over the next five years by the fertilizer, cereal grains, and horticulture industries. "The strategy is an important move to ensure our food supply and agricultural exports continue to meet international environment and health standards," says Mike McLaughlin, a soil and environmental chemist with the Commonwealth Scientific and Industrial Research Organisation Land and Water, who serves as the strategy's national coordinator. "Australia promotes the sale of its agricultural commodities to its export markets on the image of `clean and green,'" he says. "We need to make quite certain there is no increase in risk."

The Australia New Zealand Food Authority recently published revised maximum permissible concentrations for cadmium in a range of food commodities. Peter Abbott, principal toxicologist for the authority, says, "A guiding principle was that a maximum level would only be established where it serves an effective risk management function. Maximum levels have been set for those foods which provide, or may potentially provide, a significant contribution to the total dietary intake of cadmium." Such foods include chocolate, peanuts, mollusks, and certain organ meats. However, Abbott adds, food standards can only play a part in controlling cadmium exposure; improving primary commodity production practices must also be part of an overall cadmium minimization strategy.