Polluted air alters baby behaviour
A link between air pollution exposure during pregnancy and subsequent childhood behavioural problems has been revealed by a US-based study.
Air pollution is a significant health threat. According to the WHO, in 2012 one in eight deaths were linked to poor air quality. "Air pollution is now the world's largest single environmental health risk," it says.
But premature death is not the only risk arising from breathing bad air. Columbia University Medical Centre, New York, researcher Amy Margolis has found that babies exposed to pollution while still inside the womb are at increased risk of developing behavioural problems as they grow up.
In the study 462 mother-baby pairs were followed up over more than a decade.
Blood samples from the mother collected while she was pregnant were used to measure exposure to a class of compounds called polycyclic aromatic hydrocarbons (PAHs), which are a common constituent of emissions from vehicles, coal and oil burning, home heating and even tobacco smoke.
The children were assessed using a child behaviour checklist at ages 3-5, 7, 9, and 11. This was used to compute a score on a metric called the Deficient Emotional Self-Regulation Scale (DESR), which gives an indication of impulsivity lack of self-control, which are features of behavioural problems and conditions like ADHD (attention deficit hyperactivity disorder).
At all ages, and significantly so from the age of nine, children whose mothers had detectable blood PAHs during pregnancy had significantly worse DESR scores than children whose mothers tested negative.
These deficits in self-regulation may, in turn, predispose adolescents towards increased risk-taking behaviours.
Their results, which are published this week in the Journal of Child Psychology and Psychiatry, "suggest that PAH exposure may be an important underlying and contributing factor to the genesis of a range of childhood mental health problems," the team say.
They speculate that PAH exposure may damage or retard the development of sensitive circuits in the developing brain that are relevant to motor and attentional function.
"This study indicates that prenatal exposure to air pollution impacts development of self-regulation and as such may underlie the development of many childhood psychopathologies that derive from deficits in self-regulation, such as ADHD, OCD, substance use disorders, and eating disorders," says Margolis.