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Toxaphene

Toxaphene is a pesticide used extensively in farming in the 1970's and early 1980's. It was most commonly used in the cotton and soybean industry in the Southeastern United States. Toxaphene is a mixture of approximately 200 different chemicals and is produced by reacting chlorine gas with camphene. It can be most commonly found as a yellow to amber waxy solid.

Toxaphene was banned in the United States in 1990 and was banned globally by the 2001 Stockholm Convention on Persistent Organic Pollutants. It is a very persistent chemical that can remain in the environment for 1-14 years without degrading, particularly in the soil.

Testing performed on animals, mostly rats and mice, has demonstrated that toxaphene is harmful to animals. Exposure to toxaphene has proven to stimulate the central nervous system, as well as induce morphological changes in the thyroid, liver, and kidneys.

Toxaphene has been shown to cause adverse health affects in humans. The main sources of exposure are through food, drinking water, breathing contaminated air, and direct contact with contaminated soil. Exposure to high levels of toxaphene can cause damage to the lungs, nervous system, liver, kidneys, and in extreme cases, may even cause death. It is thought to be a potential carcinogen in humans, though this has not yet been proven.

Environmental Effects
When released into the environment, toxaphene can be quite persistent and exists in the air, soil, and water. In water, it can evaporate easily and is fairly insoluble. Toxaphene breaks down very slowly and has a half-life of up to 12 years in the soil. It is most commonly found in air, soil, and sediment found at the bottom of lakes or streams. It can also be present in many parts of the world where it was never used because toxaphene is able to evaporate and travel long distances through air currents. Toxaphene can eventually be degraded, through dechlorination, in the air using sunlight to break it down. The degradation of toxaphene usually occurs under aerobic conditions.

Shellfish, algae, fish and marine mammals have all been shown to exhibit high levels of toxaphene. People the Canadian Arctic, where a traditional diet consists of fish and marine animals, have been shown to consume 10 times the accepted daily intake of toxaphene. Also, blubber from beluga whales in the Arctic were found to have unhealthy and toxic levels of toxaphene. The levels of toxaphene have decreased since its ban, however, due to its persistence can still be found in the environment today.

Exposure
The three main paths of exposure to toxaphene are ingestion, inhalation, and absorption. For humans, the main source of toxaphene exposure is through ingested seafood. When toxaphene enters the body, it usually accumulates in fatty tissues. It is broken down through dechlorination and oxidation in the liver, and the byproducts are eliminated through feces.

People at high risk to toxaphene exposure are those that live near an area that has high toxaphene contamination through inhalation of contaminated air or direct skin contact with contaminated soil or water. People who eat large quantities of fish on a daily basis are more susceptible to toxaphene exposure. Exposure is also possible through drinking water when contaminated by toxaphene runoff from the soil. However, toxaphene has been rarely seen at high levels in drinking water due to toxaphene's high levels of insolubility in water.