1 October 2013. Within Europe, much discussion on environmental policy right now focuses on the possibility that industrial pollutants can interfere with the hormone system – in humans and in wildlife. Such effects can have detrimental consequences for reproduction and cancer development as well as other adverse outcomes. Today, a Lancet journal highlights the need to extend the documentation but also proposes that “the precautionary principle should perhaps be most generous for fetuses and other populations at greatest potential risk”. In this regard, one additional concern must also be considered: Are these compounds toxic to brain development?
A survey published in 2004 showed that half of 48 endocrine-disrupting substances also caused neurotoxicity. A recent update generated for the European Commission suggested that the susceptibility of the developing brain to chemical toxicity most likely also includes the neuroendocrine system – the hypophysis and related parts of the brain. These parts of the brain control the functions of the gonads, the thyroid and other hormonal glands. The close physiological relationship between brain and the endocrine system suggests that the majority of endocrine-disrupting substances may also cause chemical brain drain – and vice versa. For example, a just published review of nonylphenyl, a cosmetics ingredient well known for its endocrine disrupting effects, concluded that the compound is a developmental neurotoxicant. Given the existing knowledge on endocrine disruptors that have been examined for neurotoxicity, many other such compounds will likely be found to cause both types of effects. Thus, our physiology determines that early development is uniquely sensitive to toxic chemicals – and this vulnerability clearly relates to the brain as well as the hormone system.