PARAFFIN-STIMULATED EXCRETION OF 2,4,6,2',4'-PENTACHLOROBI[C-14]PHENYL BY RATS

Previous studies have shown long-term paraffin treatment to enhance the elimination of organochlorine xenobiotics from the rat body. The purpose of the present study was to determine the effect of paraffin feeding on the persistence of a polychlorinated biphenyl (PCB) isomer in the rat. Male rats housed in metabolism cages were fed a diet containing 1.2 ppm 2,4,6,2′,4′-pentachlorobi[14C]phenyl (PentaCB) for 1 week. After 1 day on a control diet one-half of the animals received a food ration containing 8% light liquid paraffin. The remaining animals served as controls. Four weeks after discontinuing the PentaCB-fortified diet all animals were sacrificed. Organ weights and hematocrit values were determined. Twenty different tissues were analyzed for radioactivity. The total amount of radioactivity excreted with urine and feces was measured daily. Paraffin treatment slightly depressed body weight gain and feed efficiency. During the PentaCB feeding period 31.7 and 4.8% of the radioactivity ingested were excreted with feces and urine, respectively. After 4 weeks on PentaCB-free diet the paraffin-treated rats excreted significantly more of the radioactivity (54.20±5.38%) compared to controls (42.68±5.62%). The half-lives of the second compartment of a two-compartment open model for the elimination of radioactivity from rat body were 51±11 and 141±62 days for treated and control rats, respectively. Control rats had higher residues in most of the tissues analyzed. The concentration of radioactivity in abdominal fat was 20 times higher than in any other tissue. These results suggest that administration of paraffin or possibly of other nonabsorbable lipid-like substances could be useful in the therapy of PCB poisoning. © 1979.