Cadmium, an Environmental Pollutant: A Review

Abstract

Cadmium (Cd) is a toxic heavy metal and is considered to be an environmental pollutant. Cadmium levels in the environment vary widely. Several sources of human exposure to Cd, including employment in primary metal industries, production of certain batteries, foods, soil and cigarette smoke, are known. Its inhalation has been related to different respiratory diseases and toxic effects, among which alterations of the physiological redox state in individuals exposed to the metal, have been described. Host-cell redox changes characteristic of oxidative stress facilitate the progression of viral infection through different mechanisms. Cadmium emissions to the environment are normally transported continually between the three main environmental compartments, air, water and soils, but a steady state flux is probably achieved and the general levels can reasonably well be established. The main sources of cadmium in the air are the burning of fossil fuels such as coal or oil and the incineration of municipal waste. The acute (short-term) effects of cadmium in humans through inhalation exposure consist mainly of effects on the lung, such as pulmonary irritation. Chronic (long-term) inhalation or oral exposure to cadmium leads to a build-up of cadmium in the kidneys that can cause kidney disease. Cadmium has been shown to be a developmental toxicant in animals, resulting in fetal malformations and other effects, but no conclusive evidence exists in humans. An association between cadmium exposure and an increased risk of lung cancer has been reported from human studies, but these studies are inconclusive due to confounding factors. Animal studies have demonstrated an increase in lung cancer from long-term inhalation exposure to cadmium. EPA has classified cadmium as a Group B1, probable human carcinogen. This paper is a review of the toxic nature of this metal.

Keywords: Cadmium, environment, pollution, cancer