National Drinking Water Database

Cadmium

Cadmium is a naturally occurring metal that is found in rocks and soil, typically in association with zinc, lead and copper ores. Most of the cadmium released into the environment is due to mining and smelting, fuel combustion, disposal of metal-containing products, and agricultural application of cadmium-containing phosphate fertilizers and sewage sludge. Cadmium is used in industry and consumer products, including batteries, pigments, metal coatings, plastics and some metal alloys.

Cadmium does not break down in the environment, but can change forms. Cadmium particles emitted from industrial sources into air can travel long distances before falling to the ground or water. Cadmium binds strongly to soil particles, often leading to long-lasting soil contamination (Lukin 2000). Fish, plants and animals take up cadmium from the environment (Agency for Toxic Substances and Disease Registry (ATSDR) 2008a).

In addition to occupational exposures, people are exposed to cadmium via food, drinking water and inhalation of cadmium-containing particles in the air. Cadmium is also found in cigarettes and both smokers and people exposed to secondhand smoke have higher urinary levels of cadmium. For non-smokers, most cadmium exposure comes from food. Cadmium can be released into water by natural processes, discharges from industry (including landfills) and sewage treatment plants, or by leaching from pipes that supply drinking water (ATSDR 1999d, 2008a).

The National Toxicology Program classifies cadmium as a known human carcinogen because it causes lung cancer in workers. Other studies in non-workers find associations between cadmium and cancers of the prostate, renal system (kidney) and bladder (National Toxicology Program (NTP 2002a). In animal models, cadmium causes leukemia and lymphoma in addition to tumors of the lung, testes, prostate, adrenal gland and liver (NTP 2002a). The kidney is generally considered to be the most sensitive target for cadmium toxicity following exposure in food or water (ATSDR 1999d, 2008a). Increased urinary levels of cadmium have been linked with impaired glucose metabolism and diabetes in the general population (Schwartz 2003). In animal studies, cadmium causes toxicity to the pancreas, which plays an important role in regulating blood glucose (Kacew 1976, Konishi 1990, Poirier 1983, Schwartz and Reis 2000, Waalkes 1992). Other systems affected by cadmium in humans include the gastrointestinal tract, respiratory tract and cardiovascular system. In laboratory animals, cadmium causes mortality at high doses, lung cancer, and toxicity to the liver, kidney, immune, skeletal, cardiovascular, gastrointestinal tract, reproductive and nervous systems. Cadmium also causes developmental toxicity (ATSDR 1999d).

The U.S. EPA's Toxics Release Inventory (TRI) reported that 742,721 pounds of cadmium were released in 2002, 91 percent of which was released by the solvent recovery industry (USEPA 2009i).