Burnt food smoke is dangerous for unborn babies

Smoke from burned food in the kitchen can damage the brains of unborn babies, scientists say.

Similarly, pollution from coal fires and traffic fumes disrupts parts of the developing brain that support information processing and behaviour.

Scans of inner-city children from before birth until aged seven to nine revealed those exposed to high levels of air pollution had lower white matter in their left brain, impairing intelligence and causing ADHD and aggression.

As they grew up it caused problems in concentration, reasoning, judgment, and problem-solving.

The US study looked at neurotoxic PAH - polycyclic aromatic hydrocarbons - and its effects on the brains of inner city kids.

They are contained in vehicles fumes, coal fires or oil central heating systems, power plants, wildfires and agricultural burning, tobacco smoke and hazardous waste sites

Earlier studies has shown PAH can readily cross the placenta and affects an unborn child's brain and animal studies showed that prenatal exposure impaired the development of behaviour, learning and memory.

The study by the Institute for the Developing Mind at Children's Hospital Los Angeles and Columbia University's Centre for Children's Environmental Health tested the effects on brain structure of PAH exposure during the final trimester of pregnancy.

It involved taking brain scans of 40 children in New York, followed from before birth until aged seven to nine.

They were part of a cohort of more than 600 mother-baby pairs from which Columbia researchers had previously reported exposure to airborne PAH during gestation was associated with multiple neurodevelopmental disturbances.

These included development delay by the age of three, reduced verbal IQ at five, and symptoms of anxiety and depression by seven.

Professor of paediatrics and psychiatry Bradley Peterson said: 'This is the largest MRI study to date of how early life exposure to air pollutants, specifically PAH, affect the developing mind.

'Our findings suggest that PAH are contributors to ADHD and other behavioural problems due to the pollutants' disruptive effects on early brain development.'

Results published in JAMA Psychiatry showed reductions in nearly the entire white matter surface of the brain's left hemisphere.

This loss was associated with slower processing of information during intelligence testing and more severe behavioural problems, including ADHD and aggression.

Postnatal PAH exposure - measured at age five - was found to contribute to additional disturbances in development of white matter in the dorsal prefrontal region of the brain, which is associated with concentration, reasoning, judgment, and problem-solving ability.

Prof Peterson explained that the morphological features associated with ADHD symptoms in this community sample differed from those previously reported in youth with the disorder, suggesting that exposure to high levels of PAH may produce a specific subtype of ADHD.

Although the study involved a small sample of ethnic minority children in poor inner city areas with low educational achievements, a larger study is underway.

He added: 'Our findings raise important concerns about the effects of air pollutants on brain development in children, and the consequences of those brain effects on cognition and behaviour.

'If confirmed, our findings have important public health implications, given the ubiquity of PAH in air pollutants in the general population.'

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