Everyday chemicals may affect brain development, including foetal IQ
All vertebrates – from frogs and birds to human beings – require the same thyroid hormone to thrive. Every stage of brain development is modulated by thyroid hormone and, over millions of years, the structure of this critical hormone has remained unchanged.
But, increasingly, the trappings of modern life are preventing it from playing its critical role in human brain development. Thyroid hormone signalling is very vulnerable to interference by chemicals that can scramble the endocrine communication routes between cells.
These endocrine disruptors, as they are called, include ubiquitous chemicals such as pesticides, plastifiers, flame retardants and surfactants, all of which are found in our food, non-stick pans, furniture, cleaning products, clothes and cosmetics. They are even found in the air we breathe and the water we drink.
This is bad news for our brains, and children’s brains in particular. Thyroid hormone serves multiple functions in orchestrating the production and differentiation of the 100 billion cells that make up the human brain. Without the right amount of thyroid hormone at the right time, human babies will suffer severe intellectual disabilities, developing an IQ of only about 35....