Toxicokinetics of an environmentally relevant mixture of dioxin-like PHAHs with or without a non-dioxin-like PCB in a semi-chronic exposure study in female sprague Dawley rats

Female Sprague Dawley rats were treated subcutaneously for 20 weeks with an environmentally relevant mixture of dioxin-like PHAHs with (PHAH+) or without (PHAH-) 2,2ʹ,4,4ʹ,5,5ʹ-hexachlorobiphenyl. The hepatic retention (% of given dose) of the various PHAH congeners differed considerably and in the following order: 2,3,4,7,8-pentachlorodibenzofuran (30.5–43.1%), 3,3′,4,4′,5-pentachlorobiphenyl (12.8–17.6%), 1,2,3,7,8-pentachlorodibenzo p-dioxin (6.9–10.8%), 2,3,7,8-tetrachlorodibenzo-p-dioxin (3.2–4.5%), 2,3,3′,4,4′,5-hexachlorobiphenyl (1.0–1.7%), 2,2′,4,4′,5,5′-hexachlorobiphenyl (0.5–0.8%) and 2,3ʹ,4,4ʹ,5-pentachlorobiphenyl (0.2–0.4%). A decrease of the hepatic retention of 2,3,7,8-TCDD, 1,2,3,7,8-PeCDD and 2,3,4,7,8-PeCDF was found at increasing doses of the PHAH+ mixture. 2,2′,4,4′,5,5′-Hexachlorobiphenyl increased the hepatic retention (1.3-2 times) of all congeners in the PHAH+ group, compared to the TEQ equivalent dosed PHAH- group. No interactions were observed on the ethoxyresorufin-O-deethylase activity.