Cadmium
Environmental Sources
Cadmium is a natural element in the earth’s crust. It is usually found as
a mineral combined with other elements such as oxygen (cadmium oxide),
chlorine (cadmium chloride), or sulphur (cadmium sulphate, cadmium sulphide).
Cadmium does not corrode easily and has many uses, including batteries,
pigments, metal coatings, and plastics.
Cadmium enters air from mining, industrial processes, burning coal and household
wastes (such as paints). Cadmium particles in air can travel long distances
before falling to the ground or water. It enters water and soil from waste
disposal and spills or leaks at hazardous waste sites. It binds strongly
to soil particles and some cadmium dissolves in water. It doesn’t break
down in the environment, but can change forms. Fish, plants, and animals
take up cadmium from the environment. Cadmium stays in the body a very long
time and can build up from many years of exposure to low levels.
Human Health Effects
Breathing high levels of cadmium severely damages the lungs and can cause
death. Eating food or drinking water with very high levels severely irritates
the stomach, leading to vomiting and diarrhoea. Long-term exposure to
lower levels of cadmium in air, food, or water leads to a build up of
cadmium in the kidneys and possible kidney disease. Other long-term effects
are lung damage and fragile bones.
Exposure limits
- The US EPA has set a limit of 5 parts
of cadmium per billion parts of drinking water (5 ppb). EPA doesn't allow
cadmium in pesticides.
- The US Food and Drug Administration
(FDA) limits the amount of cadmium in food colours to 15 parts per million
(15 ppm).
- The US Occupational Safety and Health
Administration (OSHA) limits workplace air to 100 micrograms cadmium per
cubic meter (100 µg/m3) as cadmium fumes and 200 µg cadmium/m3
as cadmium dust.
Links and sources:
www.atsdr.cdc.gov/tfacts5.html
www.osha-slc.gov/SLTC/pel/
www.epa.gov/oerrpage/superfund/programs/er/hazsubs/sources.htm
www.aruplab.com/guides/clt/tests/clt_alp6.jsp
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