Approaches for predicting effects of unintended environmental exposure to an endocrine active pharmaceutical, tamoxifen.

Tamoxifen is an endocrine-active pharmaceutical (EAP) that is used world-wide. Because tamoxifen is a ubiquitous pharmaceutical and interacts with estrogen receptors, a case study was conducted with this compound to (1) determine effects on reproductive endpoints in a nontarget species (i.e.

Modulation of aromatase activity as a mode of action for endocrine disrupting chemicals in a marine fish.

The steroidogenic enzyme aromatase catalyzes the conversion of androgens to estrogens and therefore plays a central role in reproduction. In contrast to most vertebrates, teleost fish have two distinct forms of aromatase. Because brain aromatase activity in fish is up to 1000 times that in mammals, fish may be especially susceptible to negative effects from environmental endocrine-disrupting chemicals (EDCs) that impact aromatase activity.

Individual effects of estrogens on a marine fish, Cunner (Tautogolabrus adspersus), extrapolated to the population level.

Endocrine-disrupting chemicals (EDCs) in the environment may alter the population dynamics of wildlife by affecting reproductive output. This study describes a matrix modeling approach to link laboratory studies on endocrine disruption with potential ecological effects. The experimental model used is cunner (Tautogolabrus adspersus), which inhabit estuarine and marine areas where sewage treatment and other discharges containing estrogenic EDCs are likely.

Relationship between reproductive success and male plasma vitellogenin concentrations in cunner, Tautogolabrus adspersus.

The gene for vitellogenin, an egg yolk protein precursor, is usually silent in male fish but can be induced by estrogen exposure. For this reason, vitellogenin production in male fish has become a widely used indicator of exposure to exogenous estrogens or estrogen mimics in the aquatic environment. The utility of this indicator to predict impacts on fish reproductive success is unclear because information on the relationship between male plasma vitellogenin and reproductive end points in male and female fish is limited.

A temperate reef fish, Tautogolabrus adspersus, (Walbaum) as a potential model species for laboratory studies evaluating reproductive effects of chemical exposure.

In ecotoxicological testing, there are few studies that report on reproductive output (egg production) of marine or estuarine fish. Cunner (Tautogolabrus adspersus) were studied as a potential model species to evaluate the impact of pollutants with estrogenic activity on reproduction in estuarine fish populations. Cunner inhabit marine and estuarine areas where contaminant discharges are likely.