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To corroborate the responses in whitefish (Coregonus lavaretus L.) exposed to elemental chlorine free (ECF) bleached-kraft pulp mill effluent (BKME) in situ. a 30-d laboratory exposure was carried out at concentrations simulating the field conditions. The flow-through exposures were conducted at four secondary (activated sludge) treated effluent (STE) concentrations: 1.3, 2.3, 3.5, and 7%. To evaluate the roleof the secondary treatment, fish were also exposed to one concentration (3.5%) of pretreated effluent (PTE) from the mill. Compared to the control, whitefish liver 7 -ethoxyresorufin-O-deethylase (EROD) activity was twofold in fish exposed to 3.5% STE, which was similar to monooxygenase induction in the field at the same effluent dilution. The exposure to 3.5% PTE caused a 12-fold relative induction in whitefish. The activity of pentoxyresorufin dealkylase showed a high correlation with EROD activity (r2 = 0.85, p < 0.01). The plasma concentration of 17Beta--estradiol was reduced by 37% (p < 0.05) in fish exposed to 3.5% STE, whereas testosterone was reduced by about 40% (p < 0.05) in fish in both 3.5% STE and PTE groups. The accumulation of chlorophenolics (CPs) and resin acids (RAs) in the bile of the fish was negligible at the three lowest STE concentrations, reflectingthe nearly nondetectable levels of CPs and RAs in secondary treated whole effluent. The measured blood parameters plasma immunoglobulin M, glucose, hemoglobin, and hernatocrit were not affected by effluent exposure. The responses obtained from the laboratory simulation well accorded with the exposures in the field, although signs of reproductive impairment could be detected in the laboratory. Overall, however,it is evident that the improvements to mill processes and wastewatertreatment have substantially reduced the load of harmful constituents in bleached-kraft mill effluent and biological impacts in the receiving environment. [ABSTRACT FROM AUTHOR]

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 ethoxy resorufin-0-deethy lase (EROD) activity in Hepa-1 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 luciferasepromoter Sediments collected near the pulp mill and from other sitesin 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 milleffluent 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-inducingpotency 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. [ABSTRACT FROM AUTHOR]