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.

Commentary: A Bird in the House: The Challenge of Being Ecologically Relevant in Captivity

“…Another challenge for comparative work, is that methods for assaying hormones vary between laboratories (e.g., enzymeimmunoassay vs. radioimmunoassay) and coefficients of variation for identical samples assayed at different labs can be as high as 70.4% (McMaster et al, 2001). Combining corticosterone data from across studies (as in Beaulieu, 2016) is likely to result in spurious conclusions in the absence of controls for differences between experimental assays, and the state of study animals (see above).…”

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

“…Analytical method Interlaboratory studies of measured steroid concentrations in white sucker [138,139] relevance, reversibility, and the ability to detect the cause of changes. For example, indicators should have low variability, to have the sensitivity required to detect a change.…”

Detailed Review Paper on Fish Screening Assays for the Detection of Endocrine Active Substances

“…This would be expected to increase variability in the measurement of these parameters from groups of asynchronous spawning fish. An additional confounding problem is high inter-laboratory variability in the measurement of plasma steroids (McMaster et al, 2001), making it difficult to determine subtle effects on steroid levels and, hence, reducing the sensitivity of the endpoint. Despite these limitations, some authors have concluded that single measures of sex-steroid levels are useful in predicting reproductive dysfunction.…”