success fail May NOV Jun 05 2009 2010 2012 104 captures 04 Aug 2008 - 14 Jun 2019 About this capture COLLECTED BY Collection: web_mon Crawl performed by Internet Archive. This data is currently not publicly accessible. TIMESTAMPS Environmental Medicine | CSEM | GREM | Continuing Education | Patient Education | PEHT | Community Section Contents Learning Objectives Introduction Sources of Cadmium Industrial Releases Natural Environment Food Chain Key Points Progress Check Case Contents Table of Contents Cover Page How to Use This Course Initial Check Cadmium Where Found Exposure Pathways Safety Standards Who is at Risk Biological Fate Pathogenic Changes Acute Effects Chronic Effects Risk Factors Clinical Assessment Laboratory Evaluation Treatment Patient Instructions More Information Posttest Answers Environmental Medicine CSEM GREM PEHT Continuing Education Online Registration Patient Education Community Education ATSDR Resources ATSDR en Español Case Studies (CSEM) Exposure Pathways Health Assessments Health Statements Interaction Profiles Interactive Learning Managing Incidents Medical Guidelines Minimal Risk Levels Priority List ToxFAQs™ ToxFAQs™ CABS Toxicological Profiles Toxicology Curriculum External Resources CDC Cancer eLCOSH EPA Healthfinder® Medline Plus NCEH NIEHS NIOSH OSHA
Agency for Toxic Substances and Disease Registry
Case Studies in Environmental Medicine (CSEM)
Where is Cadmium Found?
Upon completion of this section, you will be able to
- identify sources of cadmium in the natural environment, and
- describe how man-made uses of cadmium disperse it through the environment.
Cadmium, a rare but widely dispersed element, is found naturally in the environment. Most cadmium ore (greenockite):
- exists as cadmium sulfide,
- is refined during zinc production, and
- occurs in association with zinc.
It is released into the environment through mining and smelting, its use in various industrial processes, and enters the food chain from uptake by plants from contaminated soil or water.
Cadmium has been widely dispersed into the environment through the air by its mining and smelting as well as by other man-made routes:
- usage of phosphate fertilizers,
- presence in sewage sludge, and
- various industrial uses such as NiCd batteries, plating, pigments and plastics (ATSDR 1999).
The most important sources of airborne cadmium are smelters. Other sources of airborne cadmium include burning fossil fuels such as coal or oil and incineration of municipal waste such as plastics and nickel-cadmium batteries (which can be deposited as solid waste) (Sahmoun et al. 2005). Cadmium may also escape into the air from iron and steel production facilities.
Cadmium is used mainly:
- in metal plating,
- in producing pigments,
- in NiCd batteries,
- as stabilizers in plastics, and
- as a neutron absorbent in nuclear reactors.
When released into the atmosphere by smelting or mining or some other processes, cadmium compounds can be associated with respirable-sized airborne particles and can be carried long distances. It is deposited onto the earth below by rain or falling out of the air. Once on the ground, cadmium moves easily through soil layers and is taken up into the food chain by uptake by plants such as leafy vegetables, root crops, cereals and grains (ATSDR 1999).
Cadmium concentrations in drinking water supplies are typically less than 1 microgram per liter (μg/L) or 1 part per billion (ppb) (ATSDR 1999). Groundwater seldom contains high levels of cadmium unless it is contaminated by mining or industrial wastewater, or seepage from hazardous waste sites. Soft or acidic water tends to dissolve cadmium and lead from water lines; cadmium levels are increased in water stagnating in household pipes. These sources have not been reported to cause clinical cadmium poisoning, but even low levels of contamination add to the body's accumulation of cadmium.
Cadmium oxide also exists as small particles in air (fume) which are the result of smelting, soldering, or other high-temperature industrial processes. A certain percentage of these particles are respirable.
From the soil, certain plants (tobacco, rice, other cereal grains, potatoes, and other vegetables) take up cadmium more avidly than they do other heavy metals such as lead and mercury (Satarag et al. 2003).
Cadmium is also found in meat, especially sweetmeats such as liver and kidney. In certain areas, cadmium concentrations are elevated in shellfish and mushrooms (Jarup 2002).
Cadmium can also enter the food chain from water. In Japan, zinc mining operations contaminated the local water supplies with cadmium. Local farmers used that water for irrigation of their fields. The soil became contaminated with cadmium which led to the uptake of cadmium into their rice (Jarup 2002).
- Cadmium is mined and then released into the environment mainly through the air during smelting.
- Once in the environment, cadmium moves easily through the soil and is taken up into the food chain.
- Certain plants, such as tobacco, rice, other cereal grains, potatoes, and other vegetables, take up cadmium from the soil.
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