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United States Department of Agriculture

Agricultural Research Service

Title: Bioavailability of Food Cd As An Issue in Risk Management and Assessment

Authors
item Reeves, Phillip
item Chaney, Rufus

Submitted to: Proceedings of the Second Workshop on Risk Assessment and Management of Environmental Cadmium
Publication Type: Proceedings
Publication Acceptance Date: October 9, 2003
Publication Date: October 9, 2003
Citation: Reeves, P.G., Chaney, R.L. 2003. Bioavailability of food Cd as an issue in risk management and assessment. Proceedings of the Second Workshop on Risk Assessment and Management of Environmental Cadmium. Scientific Committee on Problems of the Environment (SCOPE) Second Workshop on Risk Assessment and Management of Environmental Cadmium. Ghent, Belgium. September 3-6, 2003.

Interpretive Summary: Cadmium is a trace element found in most foods. However, this element is not a nutrient and the consumption of too much cadmium might induce kidney malfunction. In the past, trade restrictions on the amount of cadmium allowed in food have been based on the amount of cadmium in a food, not on whether the cadmium is absorbed into the body from the ingested food. Our work with laboratory animals shows that low intakes of natural minerals such as zinc, iron, and calcium increase the absorption of cadmium up to 10-fold. Some grains, such as polished rice contain low amounts of zinc, iron, and calcium, but if grown in cadmium/zinc-polluted paddies, the rice can accumulate high amounts of cadmium. People who consume the polluted rice as a staple food might absorb more cadmium unless they also consume adequate amounts of the other minerals. Our studies were designed to determine what effects marginal intakes of zinc, iron, and calcium had on cadmium accumulation in the intestine and liver and kidneys. The results showed that rats consuming marginal amounts of these minerals accumulated about 7 times more cadmium in the upper part of the intestine than rats fed an adequate supply of these minerals. Cadmium movement out of the intestine was much slower in rats fed marginal zinc, iron, and calcium than in those fed adequate amounts. The amounts of cadmium found in the liver and kidney were much higher when the rats ate diets with marginal compared with normal amounts of zinc, iron, and calcium. The results of these studies suggest that food cadmium would be less toxic if the food containing cadmium, or the total diet, contained ample amounts of the required mineral nutrients.

Technical Abstract: Cadmium is a trace element found in most foods. However, this element is not a nutrient and the consumption of too much cadmium might induce kidney malfunction. In the past, trade restrictions on the amount of cadmium allowed in food have been based on the amount of cadmium in a food, not on whether the cadmium is absorbed into the body from the ingested food. Our work with laboratory animals shows that low intakes of natural minerals such as zinc, iron, and calcium increase the absorption of cadmium up to 10-fold. Some grains, such as polished rice contain low amounts of zinc, iron, and calcium, but if grown in cadmium/zinc-polluted paddies, the rice can accumulate high amounts of cadmium. People who consume the polluted rice as a staple food might absorb more cadmium unless they also consume adequate amounts of the other minerals. Our studies were designed to determine what effects marginal intakes of zinc, iron, and calcium had on cadmium accumulation in the intestine and liver and kidneys. The results showed that rats consuming marginal amounts of these minerals accumulated about 7 times more cadmium in the upper part of the intestine than rats fed an adequate supply of these minerals. Cadmium movement out of the intestine was much slower in rats fed marginal zinc, iron, and calcium than in those fed adequate amounts. The amounts of cadmium found in the liver and kidney were much higher when the rats ate diets with marginal compared with normal amounts of zinc, iron, and calcium. The results of these studies suggest that food cadmium would be less toxic if the food containing cadmium, or the total diet, contained ample amounts of the required mineral nutrients.

Last Modified: 10/22/2014
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