Pesticide residues in eggs and chicks from laying hens fed low levels of several chlorinated hydrocarbon pesticides.

Eighty-four Single-Comb While Leghorn laying hens housed individually in laying cages were fed rations containing less than 0.1 p.p.m. of dieldrin, DDT, heptachlor and mirex individually or in combination for 7 days and in combination for 15 weeks. DDT residues in egg yolk reached 0.043 p.p.m. by 7 days when fed in combination with the other pesticides. None of the residues were above FDA action level at 7 days and all had declined to below trace levels by 8 weeks after termination of pesticide feeding. Residues in eggs from hens fed all four pesticides for 15 weeks increased steadily for the first few weeks and then reached a plateau or increased only slightly until pesticide feeding was terminated. By the end of the 5th week of pesticide feeding all pesticides except DDT had exceeded FDA action levels for pesticides in eggs. DDT residues reached a level of 0.139 p.p.m. by 8 weeks and did not increase thereafter. Traces of the pesticides were still present 24 weeks after termination of pesticide feeding. The pesticides tested did not affect fertility of hatchability of eggs collected during the 14th and 15th weeks of pesticide feeding. Total carcass fat of chicks hatched from these eggs had 0.024 p.p.m. dieldrin, .049 p.p.m. DDT, .001 p.p.m. heptachlor epoxide and, 0.47 mirex at 1 day of age.