PHYSIOLOGICAL TOXICITY OF LOW-CHLORINE BLEACHED PULP AND PAPER-MILL EFFLUENT ON WHITEFISH (COREGONUS-LAVARETUS L-SL) - A LABORATORY EXPOSURE SIMULATING LAKE POLLUTION

In order to validate previous field observations by the authors on whi tefish, Coregonus lavaretus L. s.l, a 30-day laboratory experiment wit h concentrations (0, 1.3, 2.3, 3.5, and 7 vol%) of bleached kraft pulp and paper mill effluent (BKME) simulating those occurring in a pollut ed lake was conducted. Chlorine dioxide had almost entirely replaced c hlorine gas in the bleaching of pulp. As a consequence, the concentrat ions of adsorbable organic halogens and chlorinated phenolics (CPs) in BKME were significantly lowered compared to earlier studies. This red uction was also seen in the concentrations of CPs in the bile and CPs and extractable organic halogens in the intestinal lipids: the concent rations were low and did not depend on the dilution of BKME. In contra st, the resin acid content of bile decreased with decreasing BKME conc entration. The growth of fish was speeded up in all BKME concentration s. However, at the highest BKME concentration (7 vol%) the increase wa s lowest. The induction of hepatic ethoxyresorufin O-deethylase (EROD) activity revealed strong dose-response relationship with BKME. At 3.5 vol% BKME (corresponding to a distance of 3.3 lan from the mill sewer in the field) the EROD activity increased 12-fold. There was a tenden cy for lower activity of uridinediphosphate glucuronosyltransferase in the liver, but the decrease (34%; P < 0.05) was statistically signifi cant only at 7 vol% BKME. The activity of Liver glutathione S-transfer ase remained unchanged. All dilutions of BKME significantly depressed the concentrations of plasma immunoglobulin M (IgM). Erythrocytic conc entrations of nucleotide triphosphates decreased and of sodium increas ed as the BKME concentration increased. Also some other blood paramete rs (hematocrit, hemoglobin, plasma glucose, and aspartate aminotransfe rase) were changed in all BKME exposures, although without obvious dep endence on effluent concentration. In conclusion, there was a good agr eement between field studies and laboratory experiments using BKME con centrations occurring in the field, confirming close or similar causes for responsive toxicity endpoints. (C) 1995 Academic Press, Inc.