Residues in cattle grazed on land contaminated with heptachlor

Abstract

Heptachlor epoxide residues exceeding the maxlmum resldue limit of 0.2mgl kg have been found in fat of cattle grazed on land previously treated with heptachior prior to planting potatoes or maize. To determlne the residues accumulated in cattle exposed to Contaminated land and the rate of decline on removal from the contamination, steers were grazed on a former potato paddock which had been treated the 2 previous years wlth heptachlor at 1.lkglha. Sol residues In the paddock varied from a total of 0.42mglkg heptachlor and its epoxide at the beginning of the trial to 0.31mglkg after 16 months. Residues in the soil decreased only slightly down to a depth of 300mm. Pasture residues were less than 0.02mglkg (wet basis).Heptachior epoxide residues In the body fat of the steers Increased during 19 months of exposure and reached a maxlmum of 0.72mglkg. In 4 steers removed after 14 weeks exposure, the heptachlor epoxide concentrations continued to increase from a mean of 0.24mglkg to a mean of 0.34mglkg after a further 4 weeks. Concentrations then fell progressively with a half life of 11 weeks in the body fat. There was an apparent relationship between pasture length and body fat residue, with residues Increasing as pasture length decreased.The results of the experiments preclude the option of grazing cattle on pasture grown on soil treated with heptachlor for any extended period of tlme. it Is possible that If short pastures and soft soil are avoided, and If cattle are not exposed to contaminated land for any more than 1 week In each month, then residues would remain below the maxlmum residue limit of O.2mglkg heptachlor.#

Opinion of the Scientific Panel on contaminants in the food chain [CONTAM] related heptachlor as an undesirable substance in animal feed

“…Quantitative data on the absorption of heptachlor in laboratory animals, livestock and pets are lacking. However, several oral exposure studies conducted in rats Tashiro and Matsumura, 1978), cattle (Harradine and McDougall, 1986;Petterson et al, 1988) and broiler chickens (Wagstaff et al, 1980) provide indirect evidence of absorption of heptachlor from the gastrointestinal tract, as indicated by the presence of this compound and/or related metabolites in serum, fat and other tissues.…”

“…for 12 -18 months and of rats fed for 3 months a diet containing 30 mg heptachlor/kg feed Radomski and Davidow, 1953). Afterwards, heptachlor epoxide was identified in pig (Halacka et al, 1974), broiler chickens (Wagstaff et al, 1980), cattle (Harradine and McDougall, 1986;Petterson et al, 1988) and cow milk (Bache et al, 1960). In addition, heptachlor epoxide has been detected in tissue samples from 77 autopsies of humans performed from 1966 to 1968 in Hawaii at 1 to 32 µg/kg tissue, with highest concentrations in bone marrow and liver (Klemmer et al, 1977).…”

Occurrence of organochlorine residues in Australian meat

“…the half life of organochlorines in the adipose tissue of cattle varies from 2 to 3 months (Harradine and McDougall 1986;Petterson et d 1988), they remain violative for some time even if they are removed to non-contaminated pasture or given fodder free of organochlorines. The specific characteristics of the organochlorines which caused the residue problems are reviewed elsewhere (Seneviratna 1988).…”