Health Effects of Endocrine-Disrupting Chemicals on Wildlife, with Special Reference to the European Situation

Abstract

Many wildlife species may be exposed to biologically active concentrations of endocrine-disrupting chemicals. There is strong evidence obtained from laboratory studies showing the potential of several environmental chemicals to cause endocrine disruption at environmentally realistic exposure levels. In wildlife populations, associations have been reported between reproductive and developmental effects and endocrine-disrupting chemicals. In the aquatic environment, effects have been observed in mammals, birds, reptiles, fish, and mollusks from Europe, North America, and other areas. The observed abnormalities vary from subtle changes to permanent alterations, including disturbed sex differentiation with feminized or masculinized sex organs, changed sexual behavior, and altered immune function. For most reported effects in wildlife, however, the evidence for a causal link with endocrine disruption is weak or nonexisting. Crucial in establishing causal evidence for chemical-induced wildlife effects appeared semifield or laboratory studies using the wildlife species of concern. Impaired reproduction and development causally linked to endocrine-disrupting chemicals are well documented in a number of species and have resulted in local or regional population changes. These include: Masculinization (imposex) in female marine snails by tributyltin, a biocide used in antifouling paints, is probably the clearest case of endocrine disruption caused by an environmental chemical. The dogwhelk is particularly sensitive, and imposex has resulted in decline or extinction of local populations worldwide, including coastal areas all over Europe and the open North Sea. DDE-induced egg-shell thinning in birds has caused severe population declines in a number of raptor species in Europe and North America. Endocrine-disrupting chemicals have adversely affected a variety of fish species. In the vicinity of certain sources (e.g., effluents of water treatment plants) and in the most contaminated areas is this exposure causally linked with the effects on reproductive organs that could have implications for fish populations. However, there is also a more widespread occurrence of endocrine disruption in fish in the U.K., where estrogenic effects have been demonstrated in freshwater systems, in estuaries, and in coastal areas. In mammals, the best evidence comes from the-field studies on Baltic gray and ringed seals, and from the Dutch semifield studies on harbor seals, where both reproduction and immune functions have been impaired by PCBs in the food chain. Reproduction effects resulted in population declines, whereas impaired immune function has likely contributed to the mass mortalities due to morbillivirus infections. Distorted sex organ development and function in alligators has been related to a major pesticide spill into a lake in Florida, U.S.A. The observed estrogenic/antiandrogenic effects in this reptile have been causally linked in experimental studies with alligator eggs to the DDT complex. Although most observed effects currentl...

In utero exposure to tributyltin chloride differentially alters male and female fetal gonad morphology and gene expression profiles in the Sprague–Dawley rat

“…In mammals, high levels of TBT have been shown to alter the functions of a variety of endocrine tissues such as the pituitary, endocrine pancreas, gonads and thyroid glands [8,35,44]. We therefore examined the number and morphology of Leydig cells in testes of control fetuses and those exposed to TBT.…”

Effect-directed analysis (EDA) in aquatic ecotoxicology: state of the art and future challenges

“…Initial studies with sediments and sewage treatment plant effluents have revealed differential effects when using a combination of different bioassays that capture estrogenic, steroidogenic, dioxin-like, mutagenic/genotoxic and teratogenic effects, fractionation, and chemical analysis, demonstrating the necessity of holistic screening approaches. Also, there are increasing concerns about emerging contaminants including endocrine disrupting chemicals Vos et al 2000), perfluorinated compounds (Giesy and Kannan 2002;Jernbro et al 2007), as well as polybrominated and mixed halogenated dibenzop-dioxins and -furans (Olsman et al 2007a). For these compounds, no or only a limited number of sufficiently specific bioassays are available, and thus, such exposures often cannot be appropriately addressed.…”

Identification of Retinoic Acid Receptor Agonists in Sewage Treatment Plants

“…There exist a number of nuclear hormone receptors such as the ER, androgen receptor (AR), thyroid receptor (TR), retinoic acid receptor (RAR), and vitamin D receptor (VDR), which mediate the actions of hormones and vitamins to affect processes from reproduction to development and even general metabolism (8). Thus, environmental pollutants binding to a wide variety of nuclear hormone receptors could induce adverse effects in wildlife (9), as exemplified by a recent study that organotins caused imposex in gastropods through the involvement of retinoid X receptors (RXRs) (10).…”