An Interlaboratory Study on the Use of Steroid Hormones in Examining Endocrine Disruption

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.

Reproductive health of bass in the Potomac, USA, drainage: Part 1. Exploring the effects of proximity to wastewater treatment plant discharge

“…Males downstream had significantly ( p ϭ 0.004) higher plasma estradiol concentrations compared with those at the upstream site on the Conococheague. Whereas concentrations of reproductive hormones are useful indicators for disruption of the reproductive cycle [24], these concentrations often are confounded by natural fluctuations and environmental factors, such as water temperature influenced by rain and runoff events [25]. Concentrations of testosterone and estradiol in male SMB have been reported previously at 1 ng/ ml or less during this time of year in Japan.…”

“…Histologic observations within the gonads such as atresia, foci of pigmented cells, and gamete stage also are useful [22]. Lastly, physiological measures of plasma vitellogenin (VTG) [23] and sex steroid hormone concentrations are common endpoints of endocrine disruption [24,25].…”

Isolation of Compounds From Bleached Kraft Mill Recovery Condensates Associated With Reduced Levels of Testosterone in Mummichog (Fundulus Heteroclitus)

“…Depressions in circulating steroids in wild fish exposed to pulp mill effluent have been documented since the late 1980s [1][2][3]24,[30][31][32][33]. Steroid depressions are one of the most consistent responses associated with exposure to final effluents and are highly correlated with other reproductive abnormalities [34]. Although industry-wide process changes in the last decade have reduced acute toxicity and organochlorine discharges, reproductive effects in wild fish, including steroid depressions, continue to be observed at several sites in Canada [1][2][3].…”

Fathead minnow response to broad‐range exposure of β‐sitosterol concentrations during life‐cycle testing

“…Although shorter-term (days to weeks) ethynyl estradiol-exposure studies have shown elevated circulating vitellogenin concentrations in association with a reduction or cessation of spawning in exposed male fish relative to controls [32], results from other studies [28] show that long-term exposure to strong estrogens may activate physiological regulating mechanisms that make vitellogenin a less sensitive indicator of endocrine disruption. In addition, high variability in sex steroids and vitellogenin has been documented in other studies [33], including in unexposed control fish [21,34]. Numerous factors have been shown to contribute to variability in these endpoints including handling stress, gonadal maturation, and time of day [33,35,36], although analysis of fish tissues rather than blood plasma concentrations is thought to control for some of these [37].…”