Toxaphene

Toxaphene is a now-banned insecticide that was previously used extensively across the United States to control insect pests in cotton-growing areas in particular. It is generally encountered as a gas or as a waxy, yellowish solid with an aroma of turpentine. Toxaphene is made up of some 670 separate chemical substances and has an average chemical structure of C10H10Cl8 (it is also known as chlorinated camphene and other names). Although effective in its role as an insecticide, it has also been found to have serious negative impacts on human health including damage to the kidney, lungs, and nervous system; severe exposure to the substance might lead to death. The substance is persistent in the environment and not susceptible to biodegrading. Consequently, although it has been banned completely since 1990 (and in most of the country since 1982), its presence is still regularly found in many parts of the country. It accumulates within the bodies of mammals or fish and so its effects can start to occur years after initial exposure.

Because toxaphene will evaporate from its solid state and only imperfectly dissolves in water, it can remain active in the atmosphere for extended periods. Research indicates its pervasive presence in the Great Lakes area as well as other locations. While in use, its presence in the air was measured at one part per billion and this level has presumably declined in subsequent years. Its presence in drinking water is very rare, although it is most prevalent in those bodies of water in which it was used to eliminate what were considered excess species or numbers of fish. Its presence is greater at the lower levels of such bodies of water, where it tends to collect. However, there is comparatively little information about the impact of mild exposures to the substance or the point at which mild exposure becomes dangerous. Nevertheless, it is classified as a probable carcinogen for humans. Exposure is possible through atmospheric interaction, drinking contaminated water, or eating fish or shellfish that are contaminated. Research suggests that while the substance is detectable over wide areas, few such areas are heavily contaminated to the extent of representing a serious menace to human life.

Toxaphene is an example of the almost indiscriminate use of a substance that subsequently turns out to be dangerous to people and animals and damaging to the environment. It demonstrates the need for a properly rigorous testing regimen prior to the licensing of new chemical substances and the need to monitor their effects in the light of new learning.