EVALUATION OF THE INDUCTION OF ARYL HYDROCARBON HYDROXYLASE AND SUBCHRONIC TOXICITY OF SELECTED POLYCHLORINATED DIBENZOFURANS (ENVIRONMENT, EXPOSURE, POLLUTION, TCDD)

Limited data are available on the subchronic toxicity of chlorinated dibenzofurans (PCDF); estimates of PCDF effects have been made largely by analogy to the structurally similar dioxins. Aryl hydrocarbon hydroxylase (AHH) induction was evaluated for 25 PCDFs. AHH is induced by TCDD. Induction has been suggested as an indicator of the toxicity of polychorinated aromatic hydrocarbons. AHH was induced 2,7,2,3,7,8- and 2,3,4,7,8-CDF at half that of TCDD (strongly). Octa- and 2,8-CDF caused moderate induction. Other PCDFs tested were inactive. Sprague-Dawley rats were given 60 ppb PCDFs in feed for 90 days. PCDFs caused no changes in weight gains or feed intake. Blood parameters and organ weights were unaffected by PCDFs except for decreased corpuscular hemoglobin in females. Total lesions of the liver and kidney increased due to all PCDFs except 1,2,3,4,6,7,9-CDF. Testing of three PCDFs at higher doses confirmed that PCDFs are less toxic than TCDD and elicit different responses. Bile duct and hepatocellular necrosis were the major hepatic lesions observed. All PCDFs caused moderate renal lesions at all doses. Glomerulonephritis, proteinaceous casts and tubular degeneration were the major renal lesions observed.