Cadmium

2022-09-09

Cadmium (CAS no. 7440-43-9) is a chemical element with the symbol Cd and atomic number 48. [1] It is found naturally in the earth’s crust, where it commonly exists in combinations with other elements. For example, cadmium oxide (a mixture of cadmium and oxygen), cadmium chloride (a combination of cadmium and chlorine), and cadmium sulphide (a mixture of cadmium and sulphur) are commonly found in the environment. [2]

Cadmium is a lustrous, silver-white, ductile, very malleable metal. Its surface has a bluish tinge and the metal is soft enough to be cut with a knife, but it tarnishes in air. [3]

It is soluble in acids but not in alkalis. Cadmium doesn’t have a distinct taste or smell. [2]

Uses [4]

  • Leather tanning agent/pigment in dye (until 1990’s)
  • Rechargeable Ni-Cd batteries • Solar cells
  • Solder alloys
  • Paint and plastic production
  • Engraving
  • Cadmium vapour lamps
  • Parasite treatment in farm animals
  • Old television tubes
  • Electroplate other metals

In the Environment [5]

  • Cadmium enters soil, water, and air from mining, industry, and burning coal and household wastes.
  • Cadmium does not break down in the environment, but can change forms.
  • Cadmium particles in air can travel long distances before falling to the ground or water.
  • Some forms of cadmium dissolve in water.
  • Cadmium binds strongly to soil particles.
  • Fish, plants, and animals take up cadmium from the environment.

Sources & Routes of Exposure [6,7]

Sources of Exposure

  • Industry sources: Cadmium is obtained as a by-product from the treatment of zinc, copper, lead, and iron ores, therefore facilities that treat these ores may emit cadmium compounds to the environment (mainly water). Coal and oil burning power plants may emit cadmium compounds to air.
  • Diffuse sources: Small industrial domestic use of cadmium products will emit low levels of cadmium to the environment.
  • Natural sources: Cadmium is a naturally occurring element in the crust of the earth. Coal and other fossil fuels 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 in sulfide ore. These can result in emissions to water. Volcanic emissions contain cadmium-enriched particles.
  • Transport sources: The combustion of motor fuels (petrol) in cars, trucks, and planes result in emissions to air, and particles from tire wear may result in emissions to air, land and water.
  • Consumer products: Cadmium is found in many domestic products, e.g. tobacco products, phosphate fertilisers, polyvinyl chloride (PVC) products, photocells, petrol, oils, tyres, automobile radiators, some textile dyes and colours, electronic components, heating elements in electric kettles and hot water systems, batteries, and ceramic glazes.

Routes of Exposure

The main routes of exposure to cadmium are:

  • Inhalation
  • Ingestion
  • Skin exposure
  • Eye exposure

Health Effects [2,8]

Acute exposure to cadmium fumes may cause flu like symptoms including chills, fever, and muscle ache sometimes referred to as “the cadmium blues.” Symptoms may resolve after a week if there is no respiratory damage. More severe exposures can cause tracheo-bronchitis, pneumonitis, and pulmonary oedema. Symptoms of inflammation may start hours after the exposure and include cough, dryness and irritation of the nose and throat, headache, dizziness, weakness, fever, chills, and chest pain. Inhaling cadmium-laden dust quickly leads to respiratory tract and kidney problems, which can be fatal (often from renal failure). Ingestion of any significant amount of cadmium causes immediate poisoning and damage to the liver and the kidneys. The bones become soft (osteomalacia), lose bone mineral density (osteoporosis) and become weaker. This causes the pain in the joints and the back, and also increases the risk of fractures. In extreme cases of cadmium poisoning, mere body weight causes a fracture. The kidneys lose their function to remove acids from the blood in proximal renal tubular dysfunction. The kidney damage inflicted by cadmium poisoning is irreversible. The proximal renal tubular dysfunction creates low phosphate levels in the blood (hypophosphatemia), causing muscle weakness and sometimes coma. The dysfunction also causes gout, a form of arthritis due to the accumulation of uric acid crystals in the joints because of high acidity of the blood (hyperuricemia). Another side effect is increased levels of chloride in the blood (hyperchloremia). The kidneys can also shrink up to 30%. Other patients lose their sense of smell (anosmia).

Carcinogenicity

There is evidence that cadmium causes prostate and kidney cancer in humans, it has been shown to cause lung and testicle cancer in animals. [6] The United States Department of Health and Human Services determined that cadmium and certain cadmium compounds are probable or suspected carcinogens.[2]

Safety

First Aid Measures [7]

  • Eye exposure: Direct contact may cause redness or pain. Wash eyes immediately with large amounts of water, lifting the upper and lower eyelids. Get medical attention immediately.
  • Skin exposure: Direct contact may result in irritation. Remove contaminated clothing and shoes immediately. Wash affected area with soap or mild detergent and large amounts of water. Get medical attention immediately.
  • Ingestion: Ingestion may result in vomiting, abdominal pain, nausea, diarrhoea, headache and sore throat. Medical personnel must administer treatment for symptoms. Under no circumstances should the employer allow any person whom he retains, employs, supervises or controls to engage in therapeutic chelation. Such treatment is likely to translocate cadmium from pulmonary or other tissue to renal tissue. Get medical attention immediately.
  • Inhalation: If large amounts of cadmium are inhaled, the exposed person must be moved to fresh air at once. If breathing has stopped, perform cardiopulmonary resuscitation. Administer oxygen if available. Keep the affected person warm and at rest. Get medical attention immediately.
  • Rescue: Move the affected person from the hazardous exposure. If the exposed person has been overcome, attempt rescue only after notifying at least one other person of the emergency and putting into effect established emergency procedures. Do not become a casualty yourself. Understand your emergency rescue procedures and know the location of the emergency equipment before the need arises.

Exposure Controls & Personal Protection [9]

Engineering Controls

  • Use process enclosures, local exhaust ventilation, or other engineering controls to keep airborne levels below recommended exposure limits.
  • If user operations generate dust, fume or mist, use ventilation to keep exposure to airborne contaminants below the exposure limit.

Personal Protective Equipment

The following personal protective equipment is recommended when

handling cadmium:

  • Safety glasses;
  • Lab coat;
  • Dust respirator (be sure to use an approved/certified respirator or equivalent);
  • Gloves

Personal Protection in Case of a Large Spill:

  • Splash goggles;
  • Full suit;
  • Dust respirator;
  • Boots;
  • Gloves;
  • A self-contained breathing apparatus should be used to avoid inhalation of the product.
  • Note: Suggested protective clothing might not be sufficient; consult a specialist BEFORE handling this product.

Regulations [5,6]

United States

EPA: The Environmental Protection Agency has determined that exposure to cadmium in drinking water at concentrations of 0.04 ppm for up to 10 days is not expected to cause any adverse effects in a child. The Environmental Protection Agency has determined that lifetime exposure to 0.005 ppm cadmium is not expected to cause any adverse effects.

FDA: The Food & Drug Administration has determined that the cadmium concentration in bottled drinking water should not exceed 0.005 ppm.

OSHA: The Occupational Health and Safety Administration (OSHA) have limited workers’ exposure to an average of 5 ìg/m3 for an 8-hour workday, 40-hour workweek.

Australia

Safe Work Australia: Safe Work Australia has established an eight-hour time weighted average (TWA) exposure limit of 0.01mg/m3. The agency has also determined that cadmium and its compounds is a ‘probable carcinogen’.

Australian Drinking Water Guidelines (NHMRC and ARMCANZ, 1996): Maximum of 0.002 mg/L (i.e. 0.000002 g/L)

References

http://en.wikipedia.org/wiki/Cadmium

http://www.epa.gov/osw/hazard/wastemin/minimize/factshts/ cadmium.pdf

http://www.lenntech.com/periodic/elements/cd.htm

http://toxipedia.org/display/toxipedia/Cadmium+(Cd)

http://www.atsdr.cdc.gov/toxfaqs/tf.asp?id=47&tid=15

http://www.npi.gov.au/substances/cadmium/source.html

http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_ id=10036&p_table=STANDARDS

http://en.wikipedia.org/wiki/Cadmium_poisoning

http://www.sciencelab.com/msds.php?msdsId=9923223