25 November 2014. Hormones are essential for brain development. But it seems that the discussions on industrial chemicals that affect our endocrine system have completely ignored the most important organ – the brain. The EU Commission recently released a plan to identify the so-called endocrine-disrupting chemicals that may require attention. But not a single sentence refers to the need to detect and protect against chemical brain drain caused by hormonally-active industrial chemicals.
This oversight is puzzling and worrisome. As documented in great detail in a newly published book by Barbara Demeneix, especially the thyroid hormone is crucial for normal brain development. Sex hormones are also important and, perhaps surprisingly, the masculinization of the male brain depends on estrogen. In a wider sense, hormones are signaling molecules that are transported from one part of the body to another, and a large number of such messenger substances exists – especially in the brain. So in short, no hormones, no brain. And all of these substances are highly sensitive to adverse effects from chemical pollution.
Crucial hormone actions may be quenched by the endocrine disruptors, as these substances can disturb functions of the endocrine glands that produce the hormones or change the metabolism of the hormones, or interfere with their actions. Now, the EU countries have decided that such chemicals should be considered for possible regulation, a necessary step, as even very low exposures to toxic chemicals can lead to a variety of adverse effects.
The EU Chemicals Agency (ECHA) has recently approved the use of a one-generation reproductive toxicity test, but none of the tests available for identifying endocrine disruptors consider endocrine disruption within the brain. The hiatus must be filled, unless separate – and highly necessary – action is taken to control chemical brain drainers. Although new tests are under development under OECD auspices, including non-animal tests, again the focus does not include the protection of developing brains.
The EU decision to go ahead with regulatory action against endocrine disruptors has already provoked negative reactions from industry and from scientists with industry ties, and it most recently resulted in an open letter to the EU President from environment and health NGOs. Hormone action is necessary for brain development, and its protection against hormonally active chemicals requires public and political action. The deadline for commenting on the EU plans for identifying endocrine disruptors is 16 January 2015.