Toxaphene is a complex mixture of polychlorinated monoterpenes with a broad spectrum of pesticidal activity. Before its ban in 1982, it was the most heavily used insecticide in the U.S. and many parts of the world. When dichlorodiphenyltrichloroethane (DDT) was banned in the early 1970s, toxaphene replaced DDT as a major agricultural insecticide (Schmitt et al. 1981). Cumulative world use of toxaphene during the period 1946 to 1974 exceeded 409,000 metric tons (Toxaphene Working Group 1977). Toxaphene was first introduced in the U.S. in 1945 by Hercules Co. as Hercules 3956, a new insecticide to control a variety of insect pests. It was registered for use on more than 277 agricultural commodities and crops to control 167 major insect pests. While its primary use has been on cotton, it has also been sprayed extensively on soybeans and peanuts, and has been used as a cattle dip (Korte et al. 1979). It was used most extensively in the southern and southeastern U.S. (Carey et al. 1978, 1979) where most cotton farming is located. Toxaphene and toxaphene-like preparations (camphachlor, polychlorocamphenes, and strobane) have also been used worldwide and are still used in South America, Africa, Mexico, Romania, Hungary, the Federal Republic of Germany, Poland, and the USSR (Saleh 1987).

Toxaphene: chemistry, biochemistry, toxicity and environmental fate.

Toxicological profile for toxaphene

Soils and sediments contaminated with residues of technical toxaphene may require remedial action to reduce human health and ecological risks. Sediments were collected from a coastal wetland impacted by discharge from a former toxaphene production facility and analyzed by gas chromatography-electron capture detection and conventional and enantioselective gas chromatography-mass spectrometry in the electron capture negative ion mode. The prominent chlorobornanes (CHBs) in all samples were 2-exo,3-endo,6-exo,8,9,10-hexachlorobornane (B6-923 or Hx-Sed) and 2-endo,3-exo,5-endo,6-exo,8,9,10-heptachlorobornane (B7-1001 or Hp-Sed), metabolites of higher chlorinated components of technical toxaphene (CTTs). Pentachlorobornanes, toxaphene homologs not previously reported in environmental samples, and likely precursor CTTs were also detected. Several CHB congeners were enantioresolved, the majority of which exhibited racemic composition. These results indicate that the profile of CHBs persisting in estuarine sediment is highly modified relative to the technical mixture, and also provides strong evidence of in situ reductive dechlorination, a process that if enhanced could act to reduce bioaccumulation and toxicity of sediment-bound CTTs at toxaphene-contaminated sites.

Prominent chlorobornane residues in estuarine sediments contaminated with toxaphene

The distribution and method of movement of a hydrophobic pesticide through anaerobic saline marsh soil profiles was investigated. In the study area the flooding tidal water contained low concentrations of toxaphene. The compound accumulated only slightly in the marsh soils not flooded daily by the tides.Pesticide concentrations in the marsh soils generally decreased with depth. Dissection of the soil horizons revealed many micro-habitats with differing toxaphene concentrations. In all of the soil profiles the toxaphene concentration was greater in the macro-organic matter (MOM) than in the MOM-free soil. Highest pesticide concentrations were associated with the dead roots. Toxaphene added below the soil surface was absorbed into the plant tissue from both sandy and silty clay loam marshes. Birectional translocation occurred, with toxaphene moving down to the roots, as well as upward into the stems. The highest concentrations were in the underground plant parts. Translocation in Spartina alterniflora roots represents a rapid method of moving toxaphene through these waterlogged anaerobic soils.

Distribution and movement of toxaphene in anaerobic saline marsh soils

Ascomycetous fungi are the principal drivers of the decomposition of shoots of smooth cordgrass (Spartina alterniflora). Shoots of smooth cordgrass move into the saltmarsh food web via the decomposition system. Therefore, influences on saltmarsh ascomycetes by pollutants of saltmarshes could have far-reaching impacts. Earlier examination of impacts of severe contamination of a Georgia saltmarsh by mercury and polychlorinated biphenyls (PCBs) revealed little or no influence of the toxicants on living standing crops or sexual productivities of cordgrass ascomycetes. Extension of the examination of saltmarsh-ascomycete response to sites containing other toxic pollutants (the chlorinated organocyclic insecticide toxaphene; chromium, copper, and lead; and polycyclic aromatic hydrocarbons [PAHs]) has shown that none of the additional toxicants engendered saltmarsh-fungal responses in the form of reduced living standing crops or sexual productivities. Thus the ascomycetes of the cordgrass-decay system appear to be as resistant to anthropogenic-pollutant poisoning as smooth cordgrass itself. Unless the fungal and plant resistance mechanisms involve degradation of the toxicants, this may imply that saltmarshes are especially dangerous as receiving sites for toxic waste because they may have the potential to readily move toxicants into the food web.

Reimold Rj

Papers

Effects of estuarine dredging of toxaphene-contaminated sediments in Terry Creek, Brunswick, Ga.--1971.