Toxaphene sources

Investigations of Pulp Mills as Possible Toxaphene Sources. 235... 

Volatilization followed by atmospheric transport is thought to be the major pathway of toxaphene dispersion from source areas [221]. The time until half of the toxaphene amount disappeared from cotton fields was <14 days [221]. Nevertheless, at present toxaphene is probably still more emitted by volatilization from old residues than by fresh application [222]. Equilibration of toxaphene with air and water was estimated to be >90% gas phase-controlled and an efficient wet deposition was expected [34]. Recently, several studies have been performed to distinguish between long atmospheric transport input and local toxaphene sources [129,156,223,224]. 

First, the effects of aerobic and anaerobic culture conditions on toxaphene degradation were studied with washed P. putida cells grown on camphor and incubated with no readily usable carbon source. The radioactivities remaining in water after extraction with n-hexane were used as an indicator of metabolic activity. This was further extracted with ethyl acetate after acidification to divide this "total polar metabolites" fraction into aqueous buffer phase and ethyl acetate phase, i.e., the total polar metabolites reported refer to summation of the aqueous buffer and ethyl acetate soluble phases (Table 4). All radioactivities have been corrected by zero time controls and autoclaved 8 hr controls are included in each experiment. 

The Binational Toxics Strategy between the USA and Canada has identified 12 bioaccumulative substances (referred to as Level-1 substances) having significant persistency and toxicity to the Great Lakes system, with the goal of reducing the sources of these substances to achieve naturally occurring levels [23]. Six of the 12 Level-1 substances are OC pesticides aldrin/dieldrin, chlordane, DDT, HCB, mirex, and toxaphene. Several other OC pesticides, such as endrin, heptachlor/heptachlor epoxide, hexachloro-cyclohexanes, tetra- and penta-chlorobenzenes, and pentachlorophenol, have been identified as Level-2 substances. 

Fig.4 Individual Potential Source Contribution Function maps for toxaphene (A) Michigan (B) Indiana (C) Arkansas (D) Louisiana from Hoh and Hites [45]. Dark red represents PSCF values from 0.91 to 1.0, with shades of pink ranging down to 0.61 by tenths, and white represents from 0.41 to 0.60. Dark blue represents 0-0.10, with shades of blue ranging up to 0.40 by tenths. The green star in each map represents the sampling site. [Reproduced with permission from ACS]...

These results have significant economic implications for commercial fishers and for aboriginal peoples in the region who depend on the fishery as a major food source. In the United States no consumption of fish with greater than 4.8 xg/g wet weight is recommended based on noncancer health endpoints or 0.18 xg/g (ww) based on cancer endpoints [160]. As of December 1998 there were six fish consumption advisories for toxaphene in the USA, but they were all for locations in the southern states [ 160]. No toxaphene advisories for Great Lakes fish consumption have been issued by the Great Lakes states. 

Eisenreich SJ (1996) Toxaphene in the Great Lakes Concentrations, trends and sources. Workshop Proceedings. US Environmental Protection Agency, Chicago, IL, p 18... 

Toxaphene is among the eleven critical pollutants to be studied for sources, [3]... 

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