Heptachlor sources

This Statement was prepared to give you information about heptachlor and heptachlor epoxide and to emphasize the human health effects that may result from exposure to them. The Environmental Protection Agency (EPA) has identified 1,300 hazardous waste sites as the most serious in the nation. These sites comprise the "National Priorities List (NPL) Those sites which are targeted for long-term federal cleanup activities. Heptachlor and heptachlor epoxide have been found in at least 129 and 87 of these sites, respectively. However, we do not know how many of the 1,300 NPL sites have been evaluated for heptachlor and heptachlor epoxide. As EPA evaluates more sites, the number of sites at which heptachlor and heptachlor epoxide are found may change. This information is important for you to know because heptachlor and heptachlor epoxide may cause harmful health effects and because these sites are potential or actual sources of human exposure to heptachlor and heptachlor epoxide. 

Source When heptachlor is ingested by dairy animals, it is metabolized to heptachlor epoxide, and stored in the fatty tissues. Heptachlor epoxide is present in the excreted milk and can be present in other dairy products (Meyer et al, 1960). 

Sources. Not commercially produced formed as a metabolite of heptachlor in mammals... 

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. 

Although not as well studied, nonracemic compositions of other legacy OC pesticides, as well as of a-HCH in other waters, have been observed. The Arctic Ocean was depleted in (—)-heptachlor epoxide in all regions surveyed, while cis- and tra 5-chlordane were nearly racemic [121]. Lake Ontario was also enriched in (—)-a-HCH (mean ER of 0.85), with enantiomer compositions that did not vary with depth but did vary in the presence of racemic sources such as precipitation and water from the tributary Niagara River [128]. The York River in Chesapeake Bay had microbial consortia that degraded (+)-a-HCH upstream [129, 130]. However, greater microbial activity was observed in more brackish waters... 

The potential for OC pesticide enantiomers to be used for air-surface source apportionment was first suggested by Finizio, Bidleman, and Szeto [167], who found an air concentration gradient with the same enantiomer composition (EFs of 0.54 to 0.57 for a-HCH and 0.59 for heptachlor epoxide) up to 1.4 m above British Columbia agricultural soils with the same EFs (Figure 4.16). The subsequent measurements of nonracemic a- HCH, c/i-chlordane, and trara-chlordane in these soils [146] indicated that local and regional air burdens of these pesticides were influenced more by agricultural emissions than by trans-Pacific transport from China and India where these compounds are still... 

ORIGIN/INDUSTRY SOURCES/USES oxidation product of heptachlor formed by plants and animals, including humans, after exposure to heptachlor contaminant in heptachlor not available as a commercial product in the USA not present in commercial form... 

We now introduce some recently reported and interesting research that reinforces the basic concepts of LLE. Cantwell and eo-workers have introduced the concept of a true LLE that has been downsized to a micro extraction scale (17). In the past, the eoneept of a miero-LLE, abbreviated /xLLE, as introdueed by the EPA and promulgated through their 500 series of methods, was designed to conduct TEQA on samples from sources of drinking water. Method 508 required that 35 mL of groundwater or tap water be placed in a 40 mL vial and extraeted with exaetly 2 mL of hexane. Organochlorine pesticides such as aldrin, alachlor, dieldrin, heptachlor, and so forth are easily partitioned into the hexane. A l-/xL aliquot is then injected either manually or via autosampler into a GC-ECD to achieve... 

Obtain organochlorine and carbamate pesticide standards from a commercial source such as Polyscience Corp. or ChemService (Westchester, PA). Obtain standards of phorate and its metabolites from the manufacturer, American Cya-namid Co., Princeton, NJ. Prepare individual and mixture solutions at a level of 1 J,g/)il by dissolving 25 mg of each compound in 25 ml of solvent. For the study of chlorinated pesticides, prepare individual solutions and a mixture of heptachlor, endosulfan (Thiodan), heptachlor epoxide, lindane, dieldrin, and dico-fol (Kelthane) in hexane. For organophosphate pesticides, use phorate and its metabolites phoratoxon, phorate sulfoxide, and phoratoxon sulfoxide in ethyl acetate. For carbamates, use 3-keto carbofuran (a metabolite of carbofuran), carbaryl, and metalkamate (Bux) in ethyl acetate. 

---