Cadmium Contamination of Food

The metal cadmium is a relatively rare element and is not found in the pure state in nature (3). Cadmium has a limited number of applications but is used for a variety of consumer and industrial materials. It's principal uses include: protective plating for steel, stabilizers for polyvinyl chloride, pigments in plastics and glasses, electrode material in nickel-cadmium batteries, and as a component of various alloys (3). Because it is used as a pigment, it is often found in plastic toys and food containers.

Food products account for most of the human exposure to cadmium, except in the vicinity of cadmium-emitting industries. Human cadmium toxicity caused by contaminated rice plants was first reported in Japan in the 1950s (2). These studies showed that subsistence rice farmers had been sickened by ingesting cadmium that had passed from municipal sewage sludge used as fertilizer through the rice crop (2). Cadmium is taken up through the roots of plants to edible leaves, fruits and seeds. It will also build up in animal milk and fatty tissues (2). Therefore, people are exposed to cadmium upon consumption of cadmium containing plants or animals. Seafood, such as mollusks and crustaceans, can be a source of cadmium, as well. Please see the external link below for more information.

The toxic effects of oral cadmium exposure have been well studied in animals, and a significant body of data from exposed humans has also been accumulated. In humans, most severe cases of oral cadmium toxicity have been associated with ingestion of foods or fluids contaminated by storage in cadmium-plated containers. Death is usually due to excessive fluid loss from vomiting and diarrhea. Lethal doses in humans have been reported to range from 1,500 to 8,900 mg , corresponding to doses of about 20 to 130 mg/kg in a 70-kg adult. Oral exposure to cadmium may result in adverse effects on a number of tissues, including kidney, liver, bone, testes, the immune system, and the cardiovascular system (1). However, the levels of cadmium exposure through food, water, and air that are typical for most people are not of major health concern. For example, the intake of cadmium from the diet is usually about 0.0004 mg/kg/day, roughly ten times lower than the typical amount needed to cause kidney damage by this route (4).

The government has taken a number of steps to protect humans from excessive cadmium exposure. Following are some of these steps:

• The Environmental Protection Agency (EPA) has established limits on the quantity of cadmium that can be discharged into water or disposed of as solid wastes from factories that manufacture or employ cadmium. It is considering regulations that would limit the amount of cadmium that could be emitted into outside air. EPA has also established an interim Maximum Contaminant Level (MCL) of 0.01 mg/L (10 ug/L) for cadmium in drinking water. It has proposed a Maximum Contaminant Level Goal (MCLG) of 0.005 mg/L (5 ug/L) (1).
• The Occupational Safety and Health Administration (OSHA) has established average and maximum (ceiling) permissible exposure limits to cadmium dust and fumes in workplace air. In view of the potential carcinogenic risk from the inhalation of cadmium, the National Institute for Occupational Safety and Health (NIOSH) recommends that controls be used to reduce worker exposure to the fullest extent feasible (1).
• The Food and Drug Administration (FDA) limits the amount of cadmium that can be used in ceramic plates and cups (1). The FDA also limits the amount of cadmium in food colors to 15 parts of cadmium per million parts of food color (15 ppm) (4).

Here are some very informative external links that pertain to Cadmium in food:

• ATSDR - Public Health Statement: Cadmium (1989)
• ATSDR - ToxFAQs - Cadmium
• FDA Guidelines for Cadmium in Shellfish
• DHHS (NIOSH) Publication No. 84-116

References

1. National Institutes of Health, Cadmium. Portions developed at the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign. URL: http://tamas.nlm.nih.gov/~boyda/htdocs/ATSDR/cadmium/contents.html

2. Kaneta, M., Hikichi, H., Endo, S. and Sugiyama, N. Chemical Form of Cadmium (and other Heavy Metals) in Rice and Wheat Plants. Env. Health Persp. Vol. 65, pp. 33-37, 1986.

3. Friberg, L., Elinder, C.G., and Kjellstrom, T. IPCS, Environmental Health Criteria 134. Cadmium. World Health Organization, Geneva, 1992.

4. Agency for Toxic Substances and Disease Registry, Public Health Statement: Cadmium. ATSDR Public Health Statement, March 1989. URL: http://atsdr1.atsdr.cdc.gov:8080/ToxProfiles/phs8808.html

This Page prepared by B.T. Johnson, December 1997 UCD EXTOXNET FAQ Team.