Developmental neurotoxicity of industrial chemicals
P Grondjean, PJ Landrigan Lancet 2006, 368, 2167-78
Neurodevelopmental disorders such as autism, attention deficit disorder, mental retardation, and cerebral palsy are common, and cause lifelong disability. Their causes are mostly unknown. A few industrial chemicals (eg, lead, methylmercury, polychlorinated biphenyls [PCBs], arsenic,
and such elements as manganese, fluoride,perchlorate and toluene) are recognised causes of neuro-developmental disorders and subclinical brain dysfunction. Exposure to these chemicals during early fetal development can cause brain injury at doses much lower than those affecting adult brain function. During the 9 months of prenatal life and for the first period of life, there growth from single nerve plate to a complex highly interconnected structure with precise location of cells into precise functioning positions in a very precise programme. This makes the brain very vulnerable to toxic interference. There is some protection from the placenta but this is not a complete protection.
Recognition of these risks has led to evidence-based programmes of prevention, such as elimination of lead additives in petrol. Although these prevention campaigns are highly successful, most were initiated only after substantial delays. Another 200 chemicals are known to cause clinical neurotoxic effects in adults. Despite an absence of systematic testing, many additional chemicals have been shown to be neurotoxic in laboratory models. The toxic effects of such chemicals in the developing human brain are not known and they are not regulated to protect children. The two main impediments to prevention of neurodevelopmenial deficits of chemical origin are the great gaps in testing chemicals for developmental neurotoxicity and the high level of proof required for regulation.
There are other theories for poor development in infants, but this is a real problem and warrants care for pregnant mothers and their exposure to chemicals. How one does this in a busy moden life , goodness knows.
- Martin Eastwood