EDCs: The Hormone’s Disturber

16. November 2015
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Experts from the Endocrine Society warn about health problems due to chemicals that have effects on the endocrine system. These are said to be guilty of causing not only many common medical conditions. Exposure during prenatal and early postnatal development is also dangerous.

The international Endocrine Society published the Executive Summary of its second report on EDCs (EndocrineDisruptingChemicals) at the end of September. In it the experts explain that there is growing evidence of health risks through EDCs. Numerous new studies have been added especially relating to diabetes mellitus and obesity since the publication of the first report in 2009 suggesting that EDC exposure goes hand in hand with an increased risk for these diseases. Moreover, suspicions have been confirmed that EDCs also have an impact on the fertility of men and women, hormone-sensitive cancers such as mammarian, ovarian and prostate cancer, on thyroid disease disorders and in the development of the nervous system.

“The evidence is clearer than ever”, explains Andrea C. Gore, professor at the University of Texas (USA) and chairman of the working group that wrote the report. “EDCs interfere with the hormonal system in a manner that harms human health. Hundreds of studies point to the same conclusion, whether these be epidemiological studies of humans, basic research on animals or human research on groups that are occupationally exposed to specific chemicals”.

Worldwide about 1.5 million people die annually as a direct result of diabetes. The prevalence of obesity and diabetes has also been increasing steadily: since 1980, the number of obese persons has more than doubled, as has the number of diabetics gone up, from an estimated 151 million (2000) to 387 million (2014) . Given these figures, it is no wonder that health organisations and scientists now in both cases make reference to epidemics. According to one estimate published in March this year, EDC related diabetes and obesity cases in the EU lead to costs totalling more than 18 billion Euros per year.

Underestimated risk

EDCs are essentially exogenous substances that affect hormone levels and thus harm health. Well-known examples include bisphenol A (BPA), DDT, polychlorinated biphenyls (PCBs), dioxins and phthalates, but also other substances such as parabens and triclosan which are rumoured to have endocrinological properties. Although many substances such as PCBs are now banned, these compounds can still be demonstrated to be present in the environment. Their high persistence means that we continue to be exposed to these substances in water, air and food.

Other EDCs such as BPA are however (still seen as) relatively harmless and are therefore present in numerous everyday objects. Since BPA is used in manufacturing the plastic polycarbonate, it is contained for example in plastic dishes and drinks bottles; thermal paper used in receipts, tickets and parking tickets are a BPA source as well. In addition, BPA is used in numerous medical devices. One study of newborns in intensive care units was able to show that the BPA concentration in the urine of infants depends on the number of medical devices used. Among infants, for example, who had received a nasal oxygen supply, positive pressure ventilation or required a nasogastric probe, BPA concentration was significantly increased in the urine.

Lifetime effects

An especially dangerous factor according to the Endocrine Society is EDC exposure during a critical time window of development, such as during the pre-natal and early postnatal period. For example, animal studies have shown that exposure to tiny amounts of EDCs during prenatal development is already enough to later trigger an obesity. “EDC exposure during early development can have long-lasting or even permanent consequences”, warns Jean-Pierre Bourguignon, professor of paediatrics at the University of Liege in Belgium. It is therefore particularly important that doctors make clear to pregnant women how they can protect the unborn child.

Worldwide there are about 42 million children under five years of age who are overweight. To what extent EDCs are to blame for this we are not able to say, but as a result of rising obesity among these children there is not only the risk of cardiovascular disease but also that of getting diabetes mellitus type 2. Some EDCs seem to act specifically diabetogenically, while other EDCs have obesity-promoting (obesitogenic) properties.

EDCs also exert other additional unwanted effects on child development: they can for example also affect thyroid glands and thus affect the hormone serum levels and/or hormone function. Since thyroid hormones perform diverse tasks at different times of development, EDC health effects strongly depend on when an EDC disturbance in thyroid hormone function exactly takes place. A correlation with cognitive deficits was able to be found for certain chemicals which affect the thyroid. In addition, the mother’s EDC exposure correlates negatively to a child’s IQ.

Childless due to plastic bottles?

EDCs affect apparently not only mental but also physical development: many EDCs lead to premature puberty and to early thelarche, accompanied by a reduced body size. With male offspring a connection seems to exist between parental EDC exposure and hypospadias as well as cryptorchidism.

Considering such effects, it is no surprise that EDCs have also been suspected for a long time of reducing male and female fertility. It has, for example, been possible to show that EDCs have an influence on gametogenesis and thus on the sperm/oocyte. For couples who want children it could therefore be useful during the respective medical consultation to inform about the potentially toxic effects of EDCs on reproduction.

Cancer thanks to a receipt?

An association between EDC exposure and the incidence of hormone-sensitive cancers was able to be established with both men and women. With women there is strong evidence that early EDC exposure may alter the development of the breast permanently and thus be accompanied by an increase in breast cancer risk. What’s more the risk of cervical and ovarian cancer rises via EDCs, as do the risks relating to benign cell proliferation diseases such as endometriosis and leiomyomas due to oestrogenic/antioestrogenic effects.

But it’s not only the sexual organs of the woman which can be influenced by hormones and hormonally active substances, even men are not immune to the effects of EDCs. The incidence, progression and mortality rate of prostate cancer for example is influenced by EDCs. The exact mechanism is still unclear; steroid receptors, steroidogenic enzymes, epigenetic reprogramming as well as stem and progenitor cells of the developing and adult prostate seem to play a role. A good example showing that EDCs not only have one way of acting on a system, but have multimodal effects.

Mixing does the job

At what concentration hormonally active substances are harmful to health is something no one can say with certainty, but the Endocrine Society has in its report indicated that additive and synergistic effects between individual EDCs, and EDCs and endogenous hormones, are the norm. The effects of EDC mixtures have, however, been more poorly studied than the effects of the individual substances. Limits for individual EDCs can therefore only be taken to be a first step. The Endocrine Society in addition is therefore pushing in particular for more studies on the cause-effect relationship involving EDCs and illnesses, and for a stricter testing of chemicals on their endocrine activity. This means in particular finding out how they have exactly had effects when present at low dosage levels in combination with known EDCs at low levels. One thing seems nonetheless clear: The less we are exposed to EDCs, the better.

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