PCB 180 is a persistent and accumulative heptachlorinated non-dioxin-like polychlorinated biphenyl (NDL-PCB) abundantly present in food and the environment. Risk characterisation of NDL-PCBs has been confounded by the presence of highly potent dioxin-like (DL) impurities. We used therefore highly purified PCB 180 (DL impurities 2.7 ng TEqWHO/g PCB 180) for the 28-day toxicity study in adult rats. Groups of 5 males and 5 females were given total doses of 3, 10, 30, 100, 300, 1000 or 1700 mg/kg PCB 180 by gavage. Total dose was divided into 6 daily loading doses and 3 weekly maintenance doses. Bodyweight development was retarded at 1700 mg/kg during loading dosing, but recovered by the end of the study. Hepatic effects are reported separately (Roos et al., ibid.). Thyroid weight was increased in males. Plasma free T4 was dose-dependently decreased (maximally by 69% in males and 50% in females) in association with thyroid follicle depletion, but T3 was not affected. Increased thyroid follicle cell vacuolization is suggestive of thyroid activation. In males, vacuolization and extracellular deposits were observed in the frontal part of pituitary. Activation of adrenal cortex is demonstrated by vacuolization and hypertrophy observed in cells of zona fasciculata of the adrenal cortex. Erythrocyte parameters (red blood cell count, haematocrit, haemoglobin) were dose-dependently decreased in both genders. The results demonstrate a distinct toxicological profile of PCB 180 with some similarities with that of DL compounds, but clearly lower potency.
Acknowledgement: Funded by the European Commission (ATHON, FOOD-CT-2005-022923
2008. 205- p.