Cadmium is a metal with an 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 the United States, over 10 million pounds of cadmium are used industrially every year.
The uses for cadmium include:
- component of several metal alloys
- component of solder (metallic cement), particularly solder for aluminum
- nickel plating
- cadmium vapor lamps
- nickel-cadmium batteries
- treatment of parasites in pigs and poultry
Cadmium can be very toxic, and is dangerous if it is swallowed or inhaled. While spontaneous recovery from mild cadmium exposure is common, doses as low as 10 milligrams can cause symptoms of poisoning. There is no accepted fatal dose amount.
The symptoms of ingested cadmium poisoning are:
- increased salivation
- abdominal pain
- painful spasms of the anal sphincter
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:
- dry throat
- chest pain
- pulmonary edema, a congestive lung condition
- bronchospasm, the abnormal tightening of airways that may be accompanied by wheezing and coughing
- pneumonitis, inflammation of the lung
- muscle weakness
- leg pain
When a person has exposure to cadmium in low doses over a long period of time, symptoms may include loss of sense of smell, cough, shortness of breath, weight loss, and tooth staining. Chronic cadmium exposure may cause damage to the liver and kidneys.
Causes & symptoms
The most common cause of cadmium poisoning is a 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. 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
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 the literature on the subject is scarce. 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 the kidney during hemodialysis).
These treatments are only effective 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 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 work done in areas where there may be cadmium fumes 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.
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Canadian Centre for Occupational Health and Safety. 135 Hunter Street, East Hamilton, ON Canada L8N 1M5.
Samuel Uretsky, Pharm.D.