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| Cadmium
As Be Cd Cr Co Cu F Pb Hg Ni Tl Cadmium and solutions of its compounds are toxic, particularly in soluble and respirable forms, being more easily absorbed through inhaled dusts and fumes. Chronic dust or fume exposure can irreversibly damage the lungs, producing shortness of breath and emphysema. The risks of absorption via dermal contact is negligible. The International Agency for Research on Cancer lists cadmium metal and several of its compounds as carcinogens. Because of its toxicity, the use of cadmium is regulated by the U.S. Environmental Protection Agency (EPA) and other regulatory control agencies. (reference) Breathing high levels of cadmium may severely damage the lungs and can cause death. Eating food or drinking water with very high levels severely irritates the stomach, causing vomiting and diarrhea. Cadmium mainly accumulates in the kidneys and liver and can lead to serious kidney failure, nephrotoxicity, renal stone formation, bone disease and persistent proteinuria at high exposures. Cadmium stays in the body a very long time and can build up from many years of exposure to low levels. Recent studies have shown that the effects are reversible at low exposures, once exposure to cadmium is reduced. Other effects from acute cadmium exposures include:
Other potential effects of long-term cadmium exposure include:
A balanced diet can reduce the amount of cadmium taken into the body from food and drink. Animal studies suggest that more cadmium is absorbed into the body if the diet is low in calcium, protein, or iron, or is high in fat. Some epidemiological studies have suggested a link between drinking hard water and some degree of protection from hypertension. In some studies, younger animals absorbed more cadmium and were more likely to lose bone and bone strength than adult animals. Animals exposed en-utero to high cadmium levels suffered behavior abnormalities, learning deficits, low birth weight, and skeletal abnormalities, but birth defect potential in humans is not well known. Small portions of cadmium can cross the placenta, and cadmium can be present in breast milk if the mother carries elevated levels. The major route for cadmium intake for non smokers is ingestion of trace cadmium in foodstuffs of natural origin or from the use of phosphate fertilizers and sludge on agricultural soils. Smokers have elevated blood and tissue concentrations of cadmium from cigarette smoke. Whole blood and urine levels are useful indicators of cadmium exposure. Cadmium toxicity can be assessed by urinary excretion of low mass proteins such as alpha-1-macroglobulin or retinol binding protein. Long term exposure causes abnormalities in Ca, P and vitamin D metabolism. For the general world population, average daily cadmium intake, from all sources, is in the range of 10-25 µg/day and has decreased steadily over the past 20 years. Smoking doubles the average daily intake. The tolerable daily cadmium intake established by the World Health Organization (WHO) is 60 µg/day for adult women and 70 µg/day for adult men. Potential sources of cadmium exposure include refinery or smelter dust, plating baths, and silver soldering. Tobacco leaves naturally accumulate and concentrate relatively high levels of cadmium, which is volatilized during burning, and contributes significantly to a smoker's exposure to cadmium. Each cigarette contains from 0.5 to 2.0 µg of cadmium, 10% of which is inhaled. Smokers exhibit significantly elevated cadmium body burdens when compared to non-smokers. The Department of Health and Human Services (DHHS) has determined that cadmium and cadmium compounds may reasonably be anticipated to be carcinogens. The EPA has set a limit of 5 parts of cadmium per billion parts of drinking water (5 ppb or 0.005 mg/L). Drinking water levels which are considered "safe" for short-term exposures: For a 10-kg (22 lb.) child consuming 1 liter of water per day, a one- to ten-day exposure to 0.04 mg/L; a longer-term (up to 7 years) exposure to 0.005 mg/L.
The 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 (8-hour time-weighted average, 40-hour week). The ceiling concentration (maximum), for a period of 15 min, should not exceed 0.14 mg/m3. Cadmium oxide fume exposure (8-hour, 40-hour week) should not exceed 0.05 mg/m3, and the maximum concentration should not exceed 0.05 mg/m3. These limits are under study and may be reduced in the future. Drinking water levels which are considered "safe" for short-term exposures: For a 10-kg (22 lb.) child consuming 1 liter of water per day, a one- to ten-day exposure to 0.04 mg/L; a longer-term (up to 7 years) exposure to 0.005 mg/L. Although zinc and cadmium commonly are found together in nature, the two behave different biologically. While zinc is an essential element in almost all biological systems, playing an important role in metalloenzyme catalysis, metabolism, and genetic material replication, cadmium can damage the kidneys and lungs, and is not easily removed from affected tissues. Phyto-remediation of cadmium and other heavy metals (lead, zinc) from soils can be accomplished by the use of such hyperaccumulator plants as Alpine pennycress that can accumulate up to 25,000 mg of zinc and 1,000 mg of cadmium per kg of dry plant matter. Similar aquatic plants have been shown effective in removal of other heavy metals from water. "The Mercury-Containing and Rechargeable Battery Management Act of 1996," established uniform national labeling requirements and provides for the streamlining of regulations governing battery collection and recycling. See also: Cadmium, Cadmium absorption, Distribution & metabolism, Secondhand smoke Toxic Elements: Arsenic, Beryllium, Cadmium, Chromium, Cobalt, Copper, Fluorine, Lead, Mercury, Nickel, Thallium
Emphysema is a condition in which the walls between the alveoli or air sacs within the lung lose their ability to stretch and recoil. The air sacs become weakened and break. Elasticity of the lung tissue is lost, causing air to be trapped in the air sacs and impairing the exchange of oxygen and carbon dioxide. Also, the support of the airways is lost, allowing for airflow obstruction. Tobacco smoke causes most cases of emphysema.(reference) Nephrotoxicity is a poisonous effect of some substances, both toxic substances and medication, on the kidney. Proteinuria signifies too much protein in the urine. This may be a sign of kidney damage. |
