Effects of chlorinated paraffins on liver weight, cytochrome P-450 concentration and microsomal enzyme activities in chick embryos.

Sublethal doses of three technical preparations of chlorinated paraffins (CPs) (Cereclor 42 (C22-26, 42% Cl w/w), Cereclor 50LV (C10-13, 49% Cl w/w) and Cereclor 70L (C10-13, 70% Cl w/w)) were injected into the yolks of hens' eggs after 4 days of incubation. The liver weight, the cytochrome P-450 concentration in the liver and the liver microsomal activity of aminopyrine N-demethylase (APND), aryl hydrocarbon (benzo[a]pyrene) hydroxylase (AHH) and 7-ethoxycoumarin O-deethylase (ECOD) were determined in chick embryos incubated for 20 days. The degree of chlorination and probably also the carbon chain length of the CPs were of importance for their effects. Cereclor 70L was the most potent in causing increases in liver weight, cytochrome P-450 concentration and APND activity. Cereclor 42 was the least potent in these respects, even causing reduced APND activity. A decrease in AHH activity occurred in chick embryos treated with Cereclor 50LV, and a reduction in ECOD activity was noted as a result of treatment with Cereclor 42 and Cereclor 50LV.