Aquatic Pollution and Coastal Management

Unit 5 : Heavy metal pollution

5.5.2.Cadmium
Cadmium is a naturally occurring element in the crust of the earth. Coal and other fossil fuel contain cadmium and their combustion releases the element into the atmosphere. Cadmium is found naturally in various ores: lead and copper containing zinc, some iron ores and sulphide ore. Volcanic emissions contain cadmium-enriched particles.
Coal and oil burning power plants may emit cadmium compounds to air. Cadmium acts like other particles when in the atmosphere and is subject to deposition caused by rain or wind. The expected lifetime for particles in the atmosphere is about 5-15 days. Industrial emissions of cadmium and/or cadmium compounds can produce elevated, but still low level, concentration in the atmosphere around the source. Motor vehicles may also produce elevated levels of cadmium in areas of higher traffic. Tobacco smoke is the primary source of cadmium indoors.
Some cadmium compounds are able to leach through soils into groundwater. When cadmium compounds binds to the sediments in water (river, lakes, bore water), they are less likely to be bioavailable.
Cadmium is biopersistant and once absorbed by an organism, remains resident for many years.

Potential Hazards to Fish, Wildlife and other Non-human Biota:
Cadmium is very toxic to a variety of species of fish and wildlife. Cadmium causes behavior, growth and physiological problems in aquatic life at sublethal concentrations. Cadmium is the only metal that clearly accumulates with increasing age of animal and the kidneys are the preferred site of cadmium accumulation.

Potential Effects of Cadmium upon Humans:
All cadmium compounds are potentially harmful or toxic. Kidney and/or liver damage have followed respiratory exposure in industry. Inhalation of cadmium dusts, salts and fumes over a number of years can cause kidney and bone marrow diseases.
Cadmium contamination resulted in “Itai-Itai” disease (painful disease affecting bones) in Japan.
Inhalation-resulted in –lung cancer
Drinking water contamination leads to - bladder, kidney and liver diseases.