The focus of this report is upon information essential to the understanding of the toxic action of cadmium and the relationship between dose (exposure) and effects on human beings and animals. The therapy of cadmium poisoning has not been discussed.This review on cadmium in the environment has been performed under a contract between the U.S. Environmental Protection Agency and the Department of Environmental Hygiene of the Karolinska Institute, Sweden. The report is intended to serve as a background paper for a future Air Quality Criteria document on cadmium. Therefore, particular attention has been given to information relevant for the evaluation of risks due to long-term exposure to low concentrations of cadmium. Acute effects from short-term exposure to high concentrations are dealt with briefly. In vitro studies without bearing on the main problem have not been dealt with.The report is not limited to effects from exposure via inhalation. Newly accessible information, showing that large populations may be exposed considerably via the oral route, can elucidate chronic effects of cadmium in general. Man and animals can be victims of secondary exposure through vehicles such as food and water which have been contaminated by cadmium in air.