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The aim of the present study was to assess the toxic effects of a secondary treated effluent from a modern pulp mill processing Eucalyptus globulus on both sexes of goldfish. The effects in the exposed fish were investigated by measuring biomarkers which have been used to assess the effects of BKME on aquatic biota, with particular emphasis in fish. However, few studies have been focused on effluents from pulp mill plants processing eucalyptus. The relative proportion of cytochrome P450 (CYP1A) and vitellogenin (VTG) induction were analyzed in the livers of males and females goldfish, exposed to different concentrations of a bleached Kraft pulp mill (BKPM) effluent. Somatic indices such as HSI (hepatosomatic index) and GSI (gonadosomatic index) were calculated and a significant reduction was found in males GSI. A significant increase of HSI was recorded for both sexes exposed to 50% BKPM effluent. Exposure to BKPM effluent induced CYP1A synthesis in both sexes and decreased VTG synthesis in females according to the different effluent concentrations suggesting that the secondary treated effluent contained compounds that affect fish negatively. The results suggest that BKPM effluent can cause sex-related biochemical changes in xenobiotic metabolism. [ABSTRACT FROM AUTHOR]

Abstract: To assess the estrogenic potency of the treated domestic sewage effluent from a sewage treatment plant (STP) located in Lisbon (Chelas), 60 mirror carp (Cyprinus carpio) were exposed to different concentrations of the sewage effluent (0%, 25%, 50% and 100%) for two periods of 28 days in two different seasons (winter/spring). Vitellogenin induction in males was used as a biomarker of exposure to xenoestrogens. At the end of the experiment, blood samples were taken for vitellogenin analysis and the fish were sacrificed and dissected. Gonad samples were taken for histological evaluation of the sewage effects. The results showed an increase in vitellogenin induction in exposed fish, both males and females, depending on the different dilutions of the sewage effluent. In comparison with controls, the gonadosomatic index decreased significantly (P<0.05) in fish exposed to 100% treated effluent. Although statistically not significant, the hepatosomatic index (HSI) was high in all exposed fish. Histological abnormalities in fish gonads were evaluated and related to the different percentages of sewage effluent. Seasonal variations found in estrogenic responses were attributed to weather influences on sewage dilution. [Copyright &y& Elsevier]