Air pollution exposure may elevate Hispanic babies’ obesity risk
A study by researchers at the University of Colorado at Boulder (CU Boulder), US, is the latest to suggest that exposure to toxic air pollutants during pregnancy may cause higher rates of obesity in Hispanic babies. The Hispanic population is one of the many minority populations who tend to live in places with poor air quality in the US.
Back in 2018, the National Center for Environmental Assessment published a study showing that poor people and people of colour are exposed to as much as 1.5 times more airborne pollutants than their white counterparts. The study by CU Boulder alludes to this – about one in four Hispanic youth in the US are obese, compared to about 14% of white youth and 11% of Asian youth.
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In this study, the researchers followed 123 Hispanic mother-infant pairs from the Mother’s Milk Study, an ongoing trial in the Los Angeles region; about one-third were of normal weight pre-pregnancy, one-third overweight and one-third obese.
The researchers compared this to data from the US Environmental Protection Agency’s Air Quality System, which records hourly air quality data from ambient monitoring stations, to quantify their prenatal exposure to four classes of pollutants: PM2.5 and PM10 (inhalable particles from factories, cars and construction sites), nitrogen dioxide (an odourless gas emitted from cars and power plants) and ozone (the main ingredient in smog).
Then they followed the babies, periodically measuring their birth trajectory (weight and height, how much fat they carried and where, and so on). Babies born with smaller birth weight due to pollution tend to gain weight unusually fast. Accelerated weight gain in early life has been linked to diabetes, heart disease and weight problems in childhood and adolescence.
In addition, the researchers believe the pollutants mentioned can inflame the lungs and, in turn, cause systemic inflammation of organs, impacting metabolic processes, such as insulin sensitivity, that can influence foetal development. The pollutants have also been shown to impact gene expression in infants, potentially having life-long impact.
“We found that greater exposure to prenatal ambient air pollution was associated with greater changes in weight and adiposity, or body fatness, in the first six months of life,” said William Patterson, a CU Boulder doctoral student.
For instance, exposure to a combination of ozone and nitrogen dioxide in utero was associated with faster growth around the waist in females, while in males it was associated with slower growth in length and greater fat accumulation around the midsection. In adults, excess fat around the midsection has been linked to heart disease and diabetes.
The researchers thus recommend pregnant women take extra precautions to minimise their exposure to air pollution by closing windows on high ozone days, not exercising outdoors at times of high air pollution and steering clear of activities alongside busy roadways.
