Cadmium is a naturally occurring metallic element. In nature, cadmium occurs in combination with other elements to form cadmium compounds. Cadmium is used in some batteries, pigments, metal coatings, as a stabilizer in some plastics, and many other products.
Environmental Fate and Transport
Cadmium usually binds to organic matter in soil and is relatively immobile, unless soil pH or composition is unusual. However, cadmium can be taken up by plants and enter the food chain. Soluble forms of cadmium can migrate with groundwater or surface water. Cadmium emitted to the air can travel long distances before returning to the ground surface. Cadmium can accumulate in plants and aquatic organisms.
For nonsmokers, most cadmium exposure occurs through consumption of plants that take up cadmium from the soil. Tobacco plants accumulate cadmium from the soil and smokers on average have about twice as much cadmium in their bodies as do nonsmokers. Because cadmium can accumulate in aquatic organisms, fish from water contaminated with cadmium may be a significant source of cadmium exposure. Exposure to cadmium can also occur in workplaces where cadmium is used.
Typically, between one and ten percent of the cadmium that people consume will enter their bodies through the digestive tract. Iron deficiency may increase this percentage. A larger fraction of any cadmium that people breathe is likely to enter their bodies. Cadmium is not readily absorbed through the skin.
Cadmium tends to accumulate in the liver and kidneys and is excreted very slowly in feces and urine. The body is capable of converting much of ingested cadmium into a relatively harmless form, but this capacity can be overwhelmed by too much exposure.
Adverse health effects observed in humans from excess cadmium exposure include death, lung cancer, kidney damage, fragile bones, and/or stomach irritation. Animal studies have also found liver disease, nerve damage, brain damage, and anemia.
The preceding paragraphs are summarized from the Public Health Statement for Cadmium published by the Agency for Toxic Substances and Disease Registry.
Additional Cancer Assessments
U.S. EPA's Integrated Risk Information System states that cadmium is a probable human carcinogen.
The National Institutes of Health has determined that cadmium and cadmium compounds are known to be human carcinogens.
The International Agency for Research on Cancer has determined that "Cadmium and cadmium compounds cause cancer of the lung. Also, positive associations have been observed between exposure to cadmium and cadmium compounds and cancer of the kidney and of the prostate." (IARC, page 141).