Survey of receiving‐water environmental impacts associated with discharges from pulp mills: 2. Gonad size, liver size, hepatic erod activity and plasma sex steroid levels in white sucker

Abstract

Fish collected from the receiving areas of 12 Canadian pulp mills were examined, including sites receiving effluent from kraft mills using chlorine as well as sulfite mills. Field collections included sampling of receiving water for chemistry and toxicity testing, and sampling of local fish for organ weights, hepatic MFO (ethoxyresorufin‐O‐deethylase, EROD) activity, plasma steroid levels, and levels of liver dioxins. The main objectives of this study were to determine whether the discharge of effluent from pulp mills to sites other than Jackfish Bay was associated with physiological or biochemical disruptions in wild fish, whether there was any correlation between waste treatment and the presence of biological responses in wild fish, and whether there was any association between the use of chlorine as a bleaching agent and these responses. Although white sucker collected near bleached‐kraft mills exhibited the highest EROD induction and dioxin levels, elevated enzyme activity was observed in fish from sites that did not use chlorine, and depressions in plasma sex steroid levels was not correlated with the level of EROD activity. The absence of chlorine bleaching or the presence of secondary treatment did not eliminate responses in fish, including decreased circulating levels of sex steroids, decreased gonadal size, and increased liver size. This survey has shown that (a) induction of hepatic EROD enzymes and depressions of plasma sex steroid levels during gonadal growth are found downstream of several pulp mills; (b) these changes are seen at some mills without chlorine bleaching and at mills that have secondary treatment; (c) substantial dilutions of nontoxic effluent do not appear to remove these responses; (d) the dominant factor determining the presence or absence of responses appeared to be dilution level; and (e) lab toxicity tests on invertebrates, rainbow trout, and fathead minnows could not predict the presence of these responses in wild fish.

Exposure of Reproductively Maturing Rainbow Trout to a New Zealand Pulp and Paper Mill Effluent

“…Despite the strength of these observations, other studies have failed to "nd reproductive impacts in exposed adult "sh downstream of some mill discharges (Kloepper-Sams et al, 1994;Munkittrick et al, 1994). There has also been controversy regarding the interpretation of the largely "eldbased results on the reproductive impacts of pulp and paper e%uents in "sh .…”

Pigmented macrophage aggregates: A toxic response in fish exposed to bleached‐kraft mill effluent?

“…While the use of this biochemical response as an index of exposure of fish to BKME is well established, its use as an indicator of harmful effects is still questioned [4]. Perturbations of the metabolism of steroid hormones have been frequently reported in association with EROD induction; however, recent studies indicate that this association is not consistent [5]. Other possible deleterious consequences of CYP1A induction are (1) generation of free radicals leading to oxidant damage and (2) bioactivation of carcinogens [6].…”

Defining the role of omics in assessing ecosystem health: Perspectives from the Canadian environmental monitoring program

“…Although many of the research programs (from academia and from industry [20,27]) at the time of the development of EEM requirements incorporated physiological measures such as liver detoxification enzymes and sex steroid levels, it has not been possible to incorporate them into the standardized monitoring programs. Although legal requirements such as published, standardized methodologies, interlaboratory calibrations, and commercial availability were met, it was not possible to meet criteria defining the magnitude of change that would be considered an impact, for all species, in all situations.…”