Cadmium is a metal with an atomic number of 48 and atomic weight of 112.41. In the periodic table of the elements, cadmium is located between zinc and mercury. It is used in a large number of industrial applications. In 2011 600 t (1,322,772 lbs) of cadmium was produced in the United States. Global production of cadmium excluding the United States was 23,200 t in 2015. Consumption of cadmium has been decreasing significantly because of concerns over health and environmental issues.
The uses for cadmium include:
Cadmium can be very toxic and is dangerous if swallowed or inhaled. While spontaneous recovery from mild cadmium exposure is common, doses as low as 10 mg can cause symptoms of poisoning. There is no accepted fatal dosage.
The symptoms of ingested cadmium poisoning are:
When cadmium dust or powder is inhaled, the first symptoms are a sweet or metallic taste, followed by throat irritation. Other symptoms that may appear in three to five hours include:
Cadmium poisoning can affect anyone; however, cases of severe acute cadmium poisoning are rare. Heavy metal toxicities are relatively uncommon, but failure to recognize and treat heavy metal toxicities can result in significant morbidity and mortality. Generally, children are more susceptible to the toxic effects of heavy metals and are more prone to accidental exposures than industrial company workers. There is little to no difference in prevalence regarding sex. However, occupations with heavy metal exposure that predominantly involve a particular sex are associated with higher rates of exposure in that sex.
The most common cause of cadmium poisoning is lack of proper precautions in places where cadmium is used. In such industries, air quality should be regularly monitored. Cadmium-plated containers should never be used to store acidic foods such as fruit juices or vinegar.
Fossil fuels, such as coal and oil, release cadmium fumes into the air. Chronic cadmium poisoning is also possible through soil or water contamination. This problem may occur with improper disposal of nickel-cadmium batteries used in items such as cameras. Environmental cadmium poisoning has been associated with itai-itai disease in Japan.
Cadmium poisoning is usually diagnosed by its symptoms, particularly if there is reason to believe that the patient has been exposed to cadmium. Because patients may not request treatment for up to a day following cadmium exposure, diagnosticians should carefully question any patient who shows symptoms consistent with this condition.
Other than symptomatic treatment, there are no good options for dealing with cadmium poisoning. Hemodialysis may be used to remove circulating cadmium from the bloodstream, although literature on the subject is scarce. The addition of a chelating agent, particularly ethylenediamine tetraacetic acid (EDTA), will increase the amount of cadmium removed by the dialysate (the fluid used in dialysis to carry substances to or remove from kidneys during hemodialysis).
These treatments are effective only for oral poisoning and have no demonstrated benefit in cadmium fume inhalation.
There are no generally accepted treatments for the acute effects of cadmium poisoning. Other than dialysis, dimercaptosuccinic acid (DMSA), an oral chelating agent, has been recommended for removal of cadmium from the blood.
The prognosis depends on the nature and severity of the cadmium load. Most cases of mild exposure resolve spontaneously after a few days. In other cases, cadmium poisoning can lead to permanent damage with shortened lifespan or even death. Cadmium may be carcinogenic. Long-term exposure may also result in bone defects, including osteoporosis.
All areas where cadmium fumes may be present should be well ventilated. Ground water and soil should be checked for cadmium. Cadmium-coated containers should, in general, be avoided. They should never be used with acidic liquids such as fruit juices. Coal and oil-burning utilities should be monitored for cadmium discharge. Nickel-cadmium batteries should be recycled or disposed of as toxic waste.
Controlling exposure to cadmium can be done through engineering controls, administrative actions, and personal protective equipment (PPE). Engineering controls include such factors as isolating the source and using ventilation systems. Administrative actions include limiting the workers' exposure time and providing showers. PPE includes wearing the proper respirator protection and clothing. Primary control should focus on inhalation. Inhaled cadmium is more readily absorbed into the body than is ingested cadmium. Intake of cadmium by ingestion and skin absorption are considered to be of relatively less importance in occupational settings.
The federal government develops regulations and recommendations to protect public health. The Environmental Protection Agency (EPA), the Occupational Safety and Health Administration (OSHA), and the Food and Drug Administration (FDA) are federal agencies that develop regulations for toxic substances. Recommendations provide valuable guidelines to protect public health but cannot be enforced by law. Regulations are enforceable. The Agency for Toxic Substances and Disease Registry (ATSDR) and the National Institute for Occupational Safety and Health (NIOSH) are federal organizations that develop recommendations for toxic substances.
Regulations and recommendations can be expressed as “not-to-exceed” levels, that is, levels of a toxic substance in air, water, soil, or food that do not exceed a critical value that is usually based on levels that affect animals; they are then adjusted to levels that will help protect humans. Sometimes these not-to-exceed levels differ among federal organizations because the organizations use different exposure times (an 8-hour workday or a 24-hour day), different animal studies, or other factors. Recommendations and regulations are also updated periodically as more information becomes available.
See also Agency for Toxic Substances and Disease Registry ; Cadmium ; Environmental Protection Agency (EPA) ; Food and Drug Administration ; Mercury ; National Institute for Occupational Safety and Health ; Occupational Safety and Health Administration .
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Tolcin, Amy C. Cadmium. Washington, DC: U.S. Geological Survey, 2007.
Blanusa, Maja, et al. “Chelators as Antidotes of Metal Toxicity: Therapeutic and Experimental Aspects.” Current Medicinal Chemistry (November 2005): 2771–94.
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Occupational Safety & Health Administration, 200 Constitution Ave. NW, Washington, DC, 20210, http://www.osha.gov .
Samuel Uretsky, Pharm.D.
Revised by Karl Finley