TRIGLYCERIDE-PHOSPHOLIPID PARTITIONING AND PERSISTENCE OF ENVIRONMENTAL CHEMICALS

An isopycnic centrifugation procedure has been developed in order to determine the solubility and partitioning of chemicals in hydrated egg lecithin and triolein. The following environmental chemicals have been studied, DDT, DDE, PCBs, 2, 4-D, lindane and dieldrin. Between 5 and 100 moles of these chemicals were dissolved per 100 moles of lipid, and solubility in triolein was between 1,5 and 5-fold higher than in hydrated egg lecithin. The following partition coefficients for distribution between triolein and hydrated egg lecithin were obtained, 9.8 for DDE, 9.0 for DDT, 5.9 for the PCBs, 3.2 for dieldrin and 2.7 for lindane. A more polar metabolite of DDT, DDA, had a partition coefficient of 0.09. The non-persistent herbicide, 2,4-D, showed no detectable association with triolein. The observed preferential association with triglyceride rather than lipophilicity itself is concluded to be a major reason for the persistence of certain environmental chemicals. © 1979.