Air Pollution Exposure during Pregnancy Linked to Childhood Obesity

New research from Columbia University’s Mailman School of Public Health shows that air pollution may have a role in the high childhood obesity rates in the United States. There have been concerns that exposure to hormone-disrupting chemicals during pregnancy increases the baby’s risk of obesity later in childhood, but this new study was one of the first to present evidence that chemicals in the environmental can contribute to obesity in humans.  The study involved Hispanic and African-American children born in either South Bronx or Northern Manhattan from 1998 through 2006, whose mothers underwent monitoring for exposure to polycyclic aromatic hydrocarbon (PAH) during pregnancy. PAHs, a common urban pollutant, are released into the air from the burning of coal, diesel, oil and gas, or other organic substances such as tobacco. The children were followed and assessed at ages 5 and 7.

The researchers found that at age 5, 21 percent of the children were obese, and 25 percent of those followed to age 7 were obese. After adjusting for a number of factors including sex, ethnicity, age, birth weight, and the mother’s acceptance of public assistance, the higher prenatal PAH exposures were significantly associated with higher childhood body mass index (BMI). The results showed that compared with children of mothers with lower levels of PAH exposure during pregnancy, children of mothers with high levels of exposure were almost twice as likely to be obese at age 5, and more than twice as likely to be obese at age 7. Further, not only did the children of high exposure have higher BMIs, but also more body fat, with an average of 2.4 pounds more fat mass than the other children.

Earlier research by the same team found that the pollutants can also negatively affect childhood IQs and is linked to anxiety, depression and attention problems in young children.  Additionally, PAHs interfere with the body’s endocrine system and are known to cause cancer.  Also of note, the study did not find that the pollutants risk of obesity was influenced by household income or neighborhood poverty, nor cigarette smoke in the household or proximity to highly trafficked roads.

We spoke with Dr. Daniel Cottam, expert weight loss surgeon in Utah, about the study. He said: “This article again proves that obesity is a multifactorial disease.  Too many people assume that obesity is only due to slothfulness.  This shows that not only does high inactivity in inner city produce higher weight children, but literally the air they breath in urban centers affects the rates of obesity,” Dr. Cottam concluded.

The study authors explained that aside from moving away from the city, there are a few ways to reduce PAH exposure;  Some fuels release more of the chemicals than others and efforts in New York City to take diesel buses off the streets and retrofit oil furnaces so they burn cleaner fuel is already starting improve air quality.

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