No abstract

In recent years, there has been an increased use of the measurement of sex steroid hormone levels in the blood of animals exposed to chemicals as an indicator of reproductive impairment or an alteration in endocrine function. Although levels of hormones are often compared among animals and laboratories, there has been no study to examine the between-laboratory variability in actual steroid measurements. Therefore, we initiated a study with white sucker collected from a site receiving pulp mill effluent, previously documented as having reduced steroid levels, to address this issue. Samples of plasma and media from in vitro gonadal incubations were delivered to eight outside laboratories with the ability to measure steroid hormones. These laboratories ranged from well-established fish endocrine laboratories to wildlife toxicology laboratories, which have recently implemented the methods to measure steroid hormones. In this study, we have considered both the absolute measure of steroid content between laboratories as well as the ability to discriminate between reference and exposed populations as important criteria when evaluating the utility of these measures. Of the eight outside laboratories conducting the analyses, six detected identical site differences in circulating levels of testosterone and 17beta-estradiol to those documented by our Burlington laboratory (ON, Canada). However, the absolute value of the steroid hormones measured in the plasma varied significantly (plasma testosterone 0.6-23.1 ng/ml, 17beta-estradiol 77.6-1782.7 pg/ml) with coefficients of variation of 70.4% and 60.3% respectively. Similar results were demonstrated for the measurement of steroid hormones in media following in vitro gonadal incubation. Although there was a fair amount of variability in the absolute measure of steroid hormone levels, we would predict a far greater coherence of interlaboratory results through the sharing of reagents and the use of a common methodology between laboratories. These results are very promising, providing evidence for the inclusion of steroid hormones in monitoring endocrine disruption in wildlife species.

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.

In recent years, there has been an increased use of the measurement of sex steroid hormone levels in the blood of animals exposed to chemicals as an indicator of reproductive impairment or an alteration in endocrine function. Although levels of hormones are often compared among animals and laboratories, there has been no study to examine the between-laboratory variability in actual steroid measurements. Therefore, we initiated a study with white sucker collected from a site receiving pulp mill effluent, previously documented as having reduced steroid levels, to address this issue. Samples of plasma and media from in vitro gonadal incubations were delivered to eight outside laboratories with the ability to measure steroid hormones. These laboratories ranged from well-established fish endocrine laboratories to wildlife toxicology laboratories, which have recently implemented the methods to measure steroid hormones. In this study, we have considered both the absolute measure of steroid content between laboratories as well as the ability to discriminate between reference and exposed populations as important criteria when evaluating the utility of these measures. Of the eight outside laboratories conducting the analyses, six detected identical site differences in circulating levels of testosterone and 17beta-estradiol to those documented by our Burlington laboratory (ON, Canada). However, the absolute value of the steroid hormones measured in the plasma varied significantly (plasma testosterone 0.6-23.1 ng/ml, 17beta-estradiol 77.6-1782.7 pg/ml) with coefficients of variation of 70.4% and 60.3% respectively. Similar results were demonstrated for the measurement of steroid hormones in media following in vitro gonadal incubation. Although there was a fair amount of variability in the absolute measure of steroid hormone levels, we would predict a far greater coherence of interlaboratory results through the sharing of reagents and the use of a common methodology between laboratories. These results are very promising, providing evidence for the inclusion of steroid hormones in monitoring endocrine disruption in wildlife species.

No abstract