Free and conjugated concentrations of nine resin acids in rainbow trout (<i>Oncorhynchus mykiss</i>) following waterborne exposure

Induction of the hepatic detoxification enzyme cytochrome P4501A has been observed in fish exposed to bleached‐kraft mill effluents (BKME). P4501A content was examined in three species of wild fish exposed to BKME in a western Canadian river as part of an extensive program that included chemical monitoring, fish population studies, and other fish biochemical and physiological measurements. The Rocky Mountain whitefish Prosopium williamsoni exhibited marked induction of P4501A compared to reference whitefish, as measured by both catalytic activity and immunoreactive protein content. Similar P4501A induction was observed 4 d after reference fish were treated with 20 mg/kg β‐naphthoflavone. Whitefish P4501A levels have declined from a peak in spring 1991, following mill process modifications and concurrent with reductions in body burdens of hydrophobic compounds. Whitefish collected near the mill, moved upstream of effluent discharges, and held for 8 d showed no significant loss of hepatic P4501A‐related (ethoxyresorufin O‐deethylase, EROD) enzyme activity or P4501A protein levels. For spring 1991, correlations were found between EROD activity and measures of chronic exposure to BKME (e.g., muscle 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin content), but not between EROD and measures of acute exposure (e.g., bile content of resin acids or chlorophenolic metabolites). These and other lines of evidence indicate that the P4501A‐inducing agent(s) at this site may be neither waterborne nor rapidly eliminated. A second species, longnose sucker (Catostomus catostomus), collected near the mill exhibited modest (two‐ to threefold) P4501A induction. For both species, no significant correlations between P4501A induction and trends in other biological responses were found, as described in a companion paper. Burbot (Lota lota) had hepatic EROD activities generally in the range of reference values, despite substantial exposure to mill‐related compounds. In contrast to studies at historically degraded pulp mill sites, P4501A induction is the only major biological response observed to date at this site. As P4501A induction is not related to adverse effects, it could be best classified as an indicator of exposure to BKME.

Exposure of fish to biologically treated bleached‐kraft effluent. 2. Induction of hepatic cytochrome P4501A in mountain whitefish (Prosopium williamsoni) and other species

Kloepper-Sams

Benton

1994

Uptake and elimination of resin acids and physiological responses in rainbow trout exposed to total mill effluent from an integrated newsprint mill

Johnsen

Stuthridge

Mattsson³

et al. 1995

The effects of thermomechanical pulping effluents from an integrated newsprint mill were tested on rainbow trout (Oncorhynchus mykiss). Continuous‐flow exposures under laboratory conditions were conducted at three dilutions (1:200, 1:400, and 1:1,000) for 8 weeks, followed by a 4‐week recovery period. Sublethal effects were assessed using physiological and biochemical parameters including liver histology, hematology, serum biochemistry, and hepatic enzyme assays. Exposure was verified by analyzing water column, fish bile, and fish tissues for resin‐acid concentrations. The effluent was found to be lethally toxic to rainbow trout within 3 to 4 weeks at a dilution of 1:200. Resin‐acid concentrations in bile, muscle, gill, and liver showed a clear‐cut positive dose response. However, relatively few responses and changes in the physiological parameters analyzed were found when comparing exposed and reference fishes. The small differences in physiological parameters between the reference group and an exposure group (1:400) after a 4‐week recovery period show that the observed responses were reversible. It is noteworthy that the difference between the lowest acutely toxic concentration and the concentration at which only slight physiological responses occurred was very narrow for this effluent.

Accumulation and depuration of resin acids and fichtelite by the freshwater mussel Hyridella menziesi

Burggraaf

Langdon

Wilkins

et al. 1996

Freshwater mussels incubated in the effluent of a kraft pulp and paper mill rapidly accumulated resin acids and fichtelite in their tissues, approaching a steady state in 7 d or less. Mean bioconcentration factors (BCFs) for individual resin acids varied from 110 to 330 L/kg dry wt. for 14‐chlorodehydroabietic acid and abietic acid, respectively. The mean BCF for fichtelite was 4,900 L/kg dry wt., at least an order of magnitude greater than that of the resin acids. Resin acids were depurated rapidly from mussel tissue (biological half‐lives of 3 d), whereas fichtelite concentrations declined more slowly (biological half‐life 12 d). Depuration kinetics for these compounds appeared to be described by a first‐order process. The possibility that the uptake process for fichtelite is zero order is explored.