Could ADHD be triggered by mothers being exposed to air pollution while pregnant?

It is saddening that I have to say so but the study described below is typical epidemiological crap. They concluded what they wanted to conclude and damn the data. The focus of the study was Polycyclic aromatic hydrocarbons (PAH) in the atmosphere and in food. So what did the results show? "Maternal and cord adducts were not significantly correlated with prenatally air monitored PAH, ETS, or dietary PAH." In other words those villainous PAHs had no effects that could be detected in the blood of the mother or the blood of the placenta. So the whole theory fails at the first hurdle. All other associations observable in the data were not due to anything in the atmosphere or in the diet. A few molecules of PAH in people must have come from somewhere but it would appear that they were so few that the research could not detect their origin. The women examined were all black NYC residents from the ghettoes so perhaps they got the stuff from something to do with their lifestyle. Drugs perhaps?

Children exposed to high levels of pollution in the womb are at greater risk of suffering attention deficit hyperactivity disorder, a new study has found.

Scientists at Columbia University studied 233 non-smoking pregnant women living in New York.  They found children exposed to high levels of air pollution during pregnancy were five times more likely to have ADHD by the time they were nine years old.

The nine-year study looked at levels of common pollutants polycyclic aromatic hydrocarbons (PAH).  Researchers measured the levels of PAH in maternal and umbilical cord blood shortly after delivery.  And they repeated tests when each of the children were three and five, measuring levels of PAH in their urine.

Thirty-three children who had high levels of exposure to PAHs, as measured at birth.  Of those, 13 were diagnosed with ADHD hyperactive-impulsive subtype, seven the inattentive subtype, and 13 had both.

Professor Frederica Perera, first author of the study, said: 'Those children born to moms who were exposed to high levels of PAH during pregnancy had five times the odds of having an increased number of symptoms.'

PAHs are created when products like coal, oil, gas and rubbish are burned but not completely.  They don't burn easily, and as a result remain in the environment for long periods of time.  Most are used to conduct research though some are used to make dyes, plastics and pesticides.

One of the most common ways they enter the body is through breathing in contaminated air.

To establish children's exposure to PAHs in the womb, the scientists measured levels of fragments of the mothers' DNA bonded to PAH molecules, also known as DNA adducts, in umbilical cord blood.

Previous studies carried out by Professor Perera and her team identified links between higher levels of prenatal PAH exposure and developmental delays in children by the age of three.

They also noted lower IQ scores at five, and increased risk a child will suffer anxiety, depression and attention problems at six and seven.

The new study, published in the journal PLoS One, looked at the children's ADHD symptoms using the Child Behavior Checklist and the Conners' Parent Rating Scale - two screening tests used to diagnose the condition.

Professor Perera said this is the first time a link has been established between prenatal PAH exposure and ADHD symptoms.  She told LiveScience: 'If replicated, then these findings could lead to new ways or stronger ways, better ways, to prevent ADHD.

'By nature, environmental exposures are preventable, this we consider one possible contributor to ADHD and one that's preventable, and the findings should be followed up so that necessary preventive strategies could be taken.'

She said pregnant women concerned about the effect of pollution levels on their unborn babies, can eat plenty of fresh produce which helps offset the effects of pollutants.


Early-Life Exposure to Polycyclic Aromatic Hydrocarbons and ADHD Behavior Problems

Frederica P. Perera et al.



Polycyclic aromatic hydrocarbons are widespread urban air pollutants from combustion of fossil fuel and other organic material shown previously to be neurotoxic.


In a prospective cohort study, we evaluated the relationship between Attention Deficit Hyperactivity Disorder behavior problems and prenatal polycyclic aromatic hydrocarbon exposure, adjusting for postnatal exposure.

Materials and Methods

Children of nonsmoking African-American and Dominican women in New York City were followed from in utero to 9 years. Prenatal polycyclic aromatic hydrocarbon exposure was estimated by levels of polycyclic aromatic hydrocarbon- DNA adducts in maternal and cord blood collected at delivery. Postnatal exposure was estimated by the concentration of urinary polycyclic aromatic hydrocarbon metabolites at ages 3 or 5. Attention Deficit Hyperactivity Disorder behavior problems were assessed using the Child Behavior Checklist and the Conners Parent Rating Scale- Revised.


High prenatal adduct exposure, measured by elevated maternal adducts was significantly associated with all Conners Parent Rating Scale-Revised subscales when the raw scores were analyzed continuously (N = 233). After dichotomizing at the threshold for moderately to markedly atypical symptoms, high maternal adducts were significantly associated with the Conners Parent Rating Scale-Revised DSM-IV Inattentive (OR = 5.06, 95% CI [1.43, 17.93]) and DSM-IV Total (OR = 3.37, 95% CI [1.10, 10.34]) subscales. High maternal adducts were positivity associated with the DSM-oriented Attention Deficit/Hyperactivity Problems scale on the Child Behavior Checklist, albeit not significant. In the smaller sample with cord adducts, the associations between outcomes and high cord adduct exposure were not statistically significant (N = 162).


The results suggest that exposure to polycyclic aromatic hydrocarbons encountered in New York City air may play a role in childhood Attention Deficit Hyperactivity Disorder behavior problems.


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