Comparing Biological Responses to Mill Process Changes: A Study of Steroid Concentrations in Goldfish Exposed to Effluent and Waste Streams from a Canadian Bleached Sulphite Mill

Abstract

During the cycle 1 environmental effects monitoring (EEM) studies, wild fish collected downstream of several Nexfor Canadian pulp mills indicated reduced gonad size or fecundity. A two-year collaborative study between Nexfor Inc. and the National Water Research Institute of Environment Canada was begun to investigate the reproductive responses. The purpose of the study was to assess final effluents from Nexfor Canadian mills for their ability to affect goldfish circulating sex steroids (testosterone, 11-ketotestosterone) or production of steroids in vitro by testes from exposed fish. Along with final effluent, individual waste streams from the mill processes were tested to investigate the potential source(s) of steroid-disrupting compounds from within the mill. The study also provided a chance to study effluent potencies over time as mill processes were changed and upgraded. Goldfish exposed for 16-21 days to final effluent (100%) from a bleached sulphite mill (BSM) showed reduced testosterone and 11-ketotestosterone production by testes. Testes of goldfish exposed to undiluted final effluent had steroid production one-tenth that of controls. Fish exposed to individual waste streams (2-40%) had steroid production similar to control fish. It was difficult to assess the waste streams, as fish-exposure concentrations were inconsistent among waste streams due to differences in the acute toxicity of streams. Final effluent from the same mill collected one year later, after numerous mill upgrades (such as changes in chip handling, digester operation and better control of spills), showed an improvement: Goldfish exposed to 100% effluent had normal steroid levels. The study demonstrates the use of the goldfish steroid bioassay for detecting changes in effluent quality. Changes in processes at the mill in the year following the fish tests resulted in final effluent that had no deleterious effects on fish testes production of steroids. The environmental consequences resulting from the improvement in BSM final effluent quality will be tested during the cycle 2 EEM.

Investigation of de novo cholesterol synthetic capacity in the gonads of goldfish (Carassius auratus) exposed to the phytosterol beta-sitosterol

“…Reported rates of T production in goldfish testis range from 1 pg/g (unknown GSI) [40] to 20 pg/mg (GSI 2.2%), with the latter corresponding to a plasma T concentration of 3.0 ng/mL [14]. In vitro steroid biosynthetic capacity was not measured in the current study due to limited gonadal tissue availability; however, control male plasma T concentrations were comparable to those reported by MacLatchy & Van Der Kraak [28].…”

Use of paired fathead minnow (Pimephales promelas) reproductive test. Part 2: Source identification of biological effects at a bleached kraft pulp mill

“…Parrott et al [17] used a systematic waste stream approach to investigate sources of chemicals affecting circulating sex steroid levels in goldfish ( Carassius auratus ) at two different pulp mills. A number of waste streams and final effluent were evaluated at a bleached kraft mill (18 streams) and a bleached sulfite mill (14 streams).…”

“…However, final effluent from both mills after secondary treatment did cause significant steroid depressions, such as a 10fold drop in testosterone. At the bleached sulfite mill, implementation of a number of process changes including increased ClO 2 substitution from 60 to 65%, a reduction in solids losses from the bleach plant, reduced liquor losses through spill management, and increased aeration within secondary treatment may have resulted in elimination of effects on steroid levels [17].…”

Changes in growth and secondary sex characteristics of fathead minnows exposed to bleached sulfite mill effluent

“…Laboratory fish were exposed to final effluent to assess whether the effluent discharge had potential to cause steroid disruption or whether historical input or some other point or non–point source was responsible for the observed effects in fish captured downstream of the BSM outfall. Goldfish exposed for 21 d on‐site in 1997 to final BSM effluent had one‐tenth the circulating sex steroids of control goldfish [2]. After mill process changes made during 1997–1998, goldfish exposed to final mill effluent did not show dramatic changes in circulating sex steroid concentrations [2].…”

“…Goldfish exposed for 21 d on‐site in 1997 to final BSM effluent had one‐tenth the circulating sex steroids of control goldfish [2]. After mill process changes made during 1997–1998, goldfish exposed to final mill effluent did not show dramatic changes in circulating sex steroid concentrations [2]. Fathead minnow ( Pimephales promelas ) tests were conducted to assess whether final effluent could affect fish exposed for longer periods (130 d).…”