Endocrine disruptor

From Free net encyclopedia

Endocrine disruptors are exogenous substances that cause adverse biological effects by interfering with the endocrine system and disrupting the physiologic function of hormones.

1 The endocrine system
2 Endocrine disruptors
3 Legal approach
4 See also
5 External links

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The endocrine system

Endocrine systems are found in most varieties of animal life. The endocrine system is made up of glands, which secrete hormones, and receptor cells which detect and react to the hormones.

Hormones are released by glands and travel throughout the body, acting as chemical messengers. Hormones interface with cells that contain matching receptors in or on their surfaces. The hormone binds with the receptor, much like a key would fit into a lock.

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Endocrine disruptors

Disruption of the endocrine system can occur in various ways. Some chemicals mimic a natural hormone, fooling the body into over-responding to the stimulus, or responding at inappropriate times. Other endocrine disruptors block the effects of a hormone from certain receptors by blocking the receptor site on a cell. Still others directly stimulate or inhibit the endocrine system and cause overproduction or underproduction of hormones. Medical interventions commonly manipulate the endocrine system for the betterment of a patient, and side effects of such therapy can be interpreted as due to endocrine disruption. Substances in question are also known as Endocrine Disrupting Chemicals (EDCs) or Hormone Disrupting Chemicals (HDCs), and belong to the group of xenobiotics, foreign chemicals that affect a biological system.

Some of the most well-known examples of EDCs are 17-beta ethinyl oestradiol (the contraceptive pill), Dioxins, PCBs, PAHs, furans, phenols and several pesticides (most prominent DDT and its derivatives). Substances with estrogenic side effects include the xenoestrogens. There is a long list of substances which may disrupt the endocrine system but have not yet been scientifically proved to do so.

In recent years, some scientists have proposed that chemicals might inadvertently be disrupting the endocrine system of humans and wildlife. A variety of chemicals have been found to disrupt the endocrine systems of animals in laboratory studies, and there is strong evidence that chemical exposure has been associated with adverse developmental and reproductive effects on fish and wildlife in particular locations. The relationship of human diseases of the endocrine system and exposure to environmental contaminants, however, is poorly understood and scientifically controversial (Kavlock et al., 1996, EPA, 1997).

One example of the devastating consequences of the exposure of developing animals, including humans, to endocrine disruptors is the case of the potent drug diethylstilbestrol (DES), a synthetic estrogen. Prior to its ban in the early 1970s, doctors mistakenly prescribed DES to as many as five million pregnant women to block spontaneous abortion and promote fetal growth. It was discovered after the children went through puberty that DES affected the development of the reproductive system and caused vaginal cancer.

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Legal approach

The Congress of the United States has improved the evaluation and regulation process of drugs and other chemicals. The recent establishment of an endocrine disruptor screening program is seen as a significant step. Screening is done in vitro by examining, for instance, if an agent interacts with the estrogen receptor or the androgen receptor, and in vivo the effect of an agent can be studied in animal models, such as the uterine growth in prepubertal rodents, modifications in fish reproduction.

The multitude of possible endocrine disruptors are technically regulated in the United States by many laws, including by the Insecticide, Fungicide, and Rodenticide Acts, the Food, Drug and Cosmetic Act, the Clean Water and Safe Drinking Water Acts, and the Clean Air Act.

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