EPA Report on Monitoring Parlar Compounds

Toxaphene as a class of compounds has been regulated since the 1980s because of its persistence in the environment, and certain degradation products of toxaphene are of interest because of the manner in which they bioaccumulate in humans. Study of prolonged toxaphene usage has been hampered by the lack of availability of quality degradation products, particularly Parlar compounds. CIL has recently introduced labeled and unlabeled standards for toxaphene analysis.

Toxaphene saw extensive use as a pesticide in the United States for many decades, from its introduction in the late 1940s through its banning for all uses in 1990. It is on the list of the “dirty dozen” compounds specifically banned under the Stockholm Convention in 2004. In the US, it was used as pest control for both plants and livestock, as well as a method of keeping unwanted species of fish from small bodies of water. 

This extensive use came at a heavy cost – in large amounts it can be toxic to humans, and when used in bodies of water can enter the water supply. Because of this health risk, many locations in which toxaphene was widely used for pest control routinely test for toxaphene levels in drinking water. As with many chemicals, exposure to the elements yields many decomposition products of toxaphene, many of which have their own detrimental effects on the ecosystem as well as potential harmful effects in humans.

Certain specific breakdown products have been identified as being of particular concern, with some of the breakdown products having even greater toxicological effects than the toxaphene itself. The US EPA has identified a half-dozen specific congeners that are detrimental to human health, Parlars 26, 40, 41, 44, 50, and 62. Cambridge Isotope Laboratories, Inc. has developed labeled and unlabeled standards for many of these degradation products and is continuing to bring new toxaphene breakdown products to market.