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ENDOCRINE DISRUPTER RESEARCH / Homepage
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EU strategy on endocrine disruption

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BACKGROUND INFORMATION

icon Health effects of endocrine disrupters

Wildlife effects

Impaired reproduction and development causally linked to endocrine-disrupting chemicals are well documented in a number of species and have caused local or regional population changes. These include:

snails Masculinisation (imposex) in female marine snails by tributyltin (TBT), a biocide used in anti-fouling paints. The dogwhelk is particularly sensitive and imposex has resulted in decline or extinction of local populations worldwide, including in coastal areas all over Europe and in the open North Sea.
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birds DDE-induced egg-shell thinning in birds is probably the best example of reproductive impairment causing severe population declines in a number of raptor species in Europe and North America. Developmental exposure to the DDT complex has been firmly linked to the induction of ovotestis in male Western gulls.
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fish EDCs 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 this exposure is causally linked with effects on reproductive organs, which could have implications for fish populations. Turtles can also be affected in the same way.
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seals In mammals, the best evidence comes from the field studies on Baltic grey and ringed seals and from the semi-field studies on Wadden Sea harbour seals, where both reproduction and immune functions have been impaired by PCBs in the food chain. Other mammals affected include the polar bear, mink, rabbit, and guinea pig.
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alligators Distorted sex-organ development and function in alligators has been connected with a major pesticide spill into a lake in Florida, USA. The oestrogenic/antiandrogenic effects observed in this reptile have been causally linked in experimental studies with alligator eggs to the DDT complex.
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For terrestrial (land-living) wildlife, including aquatic mammals, exposure is primarily expected to be of dietary origin. The situation is different for aquatic wildlife where direct uptake of dissolved chemicals from the water is a significant route to exposure.

Effects on humans

For humans, possible pathways of exposure to endocrine disrupters include direct exposure via the workplace or via consumer products such as food, certain plastics, paints, detergents and cosmetics, as well as indirect exposure via the environment (air, water, soil). In general, the vulnerability of a given species will depend on the intrinsic properties of the chemical, on the magnitude, duration, frequency and means of exposure and on the way in which a given species can absorb, distribute, transform and eliminate substances. It will also depend on the sensitivity of specific organs at different stages of development.

Estrogen receptor: From H.M. Berman, J. Westbrook, Z. Feng, G. Gilliland, T.N. Bhat, H. Weissig, I.N. Shindyalov, P.E. Bourne: The Protein Data Bank. Nucleic Acids Research, 28 pp. 235-242 (2000)

The endocrine-disrupter hypothesis was originally formulated for xenoestrogens, i.e. chemicals, which affect the estrogen-signalling pathway. The greatest attention to endocrine disruption has focused on estrogenic effects, but a clear cause-effect relationship has not yet been established. However, it is now becoming generally accepted that compounds of various types can interact with different components in several cell-regulatory systems, including the steroid and thyroid hormone receptor families. Aside from the drug DES (synthetic oestrogen), environmental oestrogens have never been proved to cause human health problems, so we can only speculate on possible human health effects documented from animal studies.

EDCs which act via receptors of the steroid receptor super-family can have effects on many organs of the body. Steroid receptors for oestrogens, androgens, adrenocorticoid and thyroid hormones are found in practically all cells of the body. The functions of the brain, the cardiovascular, the skeletal and the urogenital systems are regulated by these hormones and can therefore be affected by EDCs. An EDC with a defined action in one organ (e.g. oestrogenic activity) can exert similar or no oestrogenic or even antagonistic effects in other organs.

Potential human health effects caused by EDCs:

  • For women:
    Breast and reproductive organ tissue cancers, fibrocystic disease of the breast, polycystic ovarian syndrome, endometriosis, uterine fibroids and pelvic inflammatory diseases. Declining sex ratio (fewer women)
  • For men:
    Poor semen quality (low sperm counts, low ejaculate volume, high number of abnormal sperm, low number of motile sperm), testicular cancer, malformed reproductive tissue (undescended testes, small penis size), prostate disease and other recognised abnormalities of male reproductive tissues.

Other potential effects: impaired behavioural/mental, immune and thyroid function in developing children; osteoporosis, precocious puberty.

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