Researchers found that air pollution, smoking and a person’s built environment may play role in obesity in children.
Air pollutants and population density are increasing the chances of childhood obesity, and scientists are just starting to understand which chemicals and urban factors are the riskiest, according to a new US study.
Researchers reviewed 77 factors during pregnancy and 96 during childhood and found that air pollution, smoking and a person’s built environment may play a role in obesity in children from birth to age 11.
Prior to this, researchers have studied single exposures individually but have not analyzed the entire exposome – a comprehensive characterization of all exposures.
“This is one of the first studies that actually manages to measure so many different variables and so many factors of the environment and then tries to analyze them all together,” said Martine Vrijheid, the lead author of the study, published in the peer-reviewed Environmental Health Perspectives.
Of the children studied, 29% were either overweight or obese. That figure is likely to have risen since the Covid-19 stay-at-home orders, Vrijhei said.
Air pollution was correlated with the highest obesity rates and body mass index (BMI) measurements. One study of mice linked air pollution with internal inflammation, which decreased metabolism and led to weight gain.
Other research has shown that breathing dirty air during pregnancy is linked to lower birth weights. Vrijheid said the body tries to play “catch up” after birth, which speeds up weight gain and induces obesity.
But exposomes are hard to evaluate – environmental factors can be harmful or beneficial, and it’s challenging to determine which ones outweigh others. For example, urban areas have more air pollution but are more walkable than some other habitats, which increases physical activity and decreases obesity, the study found.
The built environment might trigger obesity, too. According to the study, children who live in a densely-populated area with fewer parks and less public transportation have higher BMIs because they have fewer chances for physical activity.
The study also analyzed common toxic exposures, including PFAS chemicals, PCBs and heavy metals, but results were inconclusive because blood concentration samples could have been affected by other things, like the metabolic cycle.
There’s still a lot that scientists don’t know about the entirety of prenatal and childhood exposures, which Vrijheid stressed is an important period in human development to study.
“Pregnancy and the early years of life are vulnerable periods because the organs of the fetus and the child are developing very rapidly, so they are susceptible to any possible damage from the environment,” she said. “It’s an important part to protect children from the damage of environmental pollutants.”