Induction of EROD activity in HEPA-1 mouse hepatoma cells and estrogenicity in MCF-7 human breast cancer cells by extracts of pulp mill effluents, sludge, and sediment exposed to effluents

Extracts of effluents and sludges from the primary and secondary clarifiers of an activated sludge treatment plant at a Finnish bleached kraft pulp and paper mill were analyzed in two cell bioassays. Total dioxin-like activities were determined by measuring the induction of ethoxyresorufin-O-deethylase (EROD) activity in Hepa-l mouse hepatoma cells. Estrogenicity was studied by measuring luciferase activity in MCF-7 ERE-luc, which are MCF-7 human breast cancer cells stably transfected with an estrogen-responsive element linked to a luciferase promoter. Sediments collected near the pulp mill and from other sites in Lake Saimaa as well as fillets of whitefish exposed to effluents were examined and EROD activity was determined for complex mixtures of compounds extractable with dichloromethane (DCM) from the pulp mill effluent or compounds collected by semipermeable membrane devices (SPMDs) from the same effluent. Extracts of effluents, particulates, SPMDs, and sludges all caused measurable EROD induction. Because the induction potencies of the total DCM extract and the fraction of neutral compounds were similar, it was concluded that most of the EROD induction in pulp mill effluents was due to neutral compounds. Sediment collected from the vicinity of the pulp mill had greater EROD-inducing potency compared to that of the control sites from the same lake. Induction of EROD potencies of muscle extracts of whitefish exposed to diluted effluents were not significantly greater than those of control fish exposed to dilution water only. All extracts contained some estrogen agonist activity when tested in the MCF-7 bioassay.