Canadian study measures impact of air pollution on babies

A recent study published by Environmental Health Perspectives (EHP) examined how the levels of air pollution in four Canadian cities are impacting the health of unborn and newly born children up to one year of age.

The study examined how evidence suggests prenatal air pollution could create changes to a person's DNA Methylation — a biological function of not producing some proteins — in a way that it could create longterm health problems.

The study said that persistent air pollution could lead to an increase in childhood asthma.

"Prenatal and early-life air pollution exposures are associated with an increased risk of childhood asthma, which is characterized by wheezing, difficulty breathing, chest tightness, and bronchial hyperresponsiveness," the authors wrote.

They added that childhood asthma is often preceded by asthma-like symptoms and immune disorders, including wheeze and allergies (atopy), in what is known as the “atopic march”. 

One of the study methods involved drawing blood samples from the mothers and umbilical cord blood from the prenatal children. 

Part of the EHP study focussed on a cohort of eligible mothers, living in Toronto, Vancouver, Winnipeg and Edmonton. The study involved roughly 3,600 mothers and roughly 3,500 infants that ranged in age from six weeks to 39 weeks.  Prenatal blood samples were also included, said the study.

Many of the mothers and their unborn babies came from situations where they were exposed to air pollution caused by sitting in slow-moving cars during traffic jams. The study measured the impact of DNA methylation (DNAm) change and nitrogen dioxide (NO2) on mothers and children as a result of outdoor exposures.

"Levels of ambient NO2 vary annually in Canada, with the highest levels typically occurring during colder periods, which occur between November and February across the country. We hypothesized that children exposed to higher levels of air pollution during critical developmental periods may experience larger magnitudes of DNAm alterations," the authors wrote.  

The study also said that while traffic-related air pollution, that measures NO2, is generally accepted to impact people and result in DNAm changes, there is still no definitive evidence that the impact carries forward into a child's life. 

"Despite the notion that persistent DNAm alterations are more likely to contribute to clinically relevant health outcomes, most studies examining prenatal NO2 exposure identify DNAm changes only at a single time point, typically at birth," said the study.  

"Although these findings provide support that prenatal air pollution exposure alters DNAm in cellular pathways related to oxidative stress and inflammation at birth, it remains unclear which of these changes persist into childhood." 

A complete text version of the EHP article is available online.

Len Gillis covers health care and mining for Sudbury.com.