Exposure to common air pollution may cause childhood obesity by disrupting children's ability to control impulses, according to first-of-its-kind peer-reviewed research from Mt Sinai researchers. The study, published in the journal Obesity, found that babies exposed to higher levels of particulate matter 2.5 (PM2.5) during their first year of life were more likely to develop difficulties with impulse control later in childhood, which was then linked to higher body fat and higher BMI in children between four to eight years old.
Novel Pathway Identified
PM2.5 is a neurotoxin composed of microscopic solid or liquid particles suspended in air, commonly from traffic emissions and fossil fuel burning. It is considered a probable carcinogen and linked to health problems including dementia and strokes. Previous research has shown PM2.5 has obesogenic properties that can disrupt metabolism, but this study is the first to identify impulse control as a potential pathway.
“A lot of the obesity research primarily focuses on – and is being shaped by – diet and physical activity, and a lot may not include environmental exposures, including air pollution,” said Jamil Lane, a co-author with Mt Sinai’s Icahn School of Medicine. “Our study is novel in that we are showing that high levels of air pollution early in life may cause more difficulty with self-regulation, which contributes to weight gain.”
Study Details and Findings
The researchers analyzed data from 434 children born largely between 2007-2008 in Mexico City who are part of a longitudinal health study. They modeled ambient PM2.5 levels during pregnancy and the children’s first year of life, which Lane called a “very sensitive window” for brain development. Later, children were assessed for impulsivity and obesity measures.
The group with the highest PM2.5 exposure showed a pattern of high impulsivity, reflecting significant deficits in inhibitory control. “Our study shows that greater early exposure to PM2.5 in the first year of life is associated with alterations in inhibitory control function in childhood,” the authors wrote. “The effect is likely due to altered eating behaviors related to inhibitory control that are programmed early in life.”
About 42% of American adults were estimated to be obese in 2018. It is well-established that poor inhibitory control is linked to obesity. Bob Wright, a study co-author and environmental epidemiologist at Mt Sinai, said the authors wondered if PM2.5's neurotoxic effects and obesity were “part of the same processes”.
Implications and Expert Reactions
Cecilia Moura, a clean transportation scientist with the Union of Concerned Scientists who was not involved with the study, said the research was sound and the novel findings “indicate there is sufficient evidence supporting the correlation to motivate policies and regulations that mitigate exposure to PM2.5”.
The study acknowledges limitations, including a small population size and limited covariates. However, the authors advise that individuals can take steps to protect themselves and their children. Home HEPA air filtration systems are effective at removing PM2.5, while furnace filters rated at MERV 13 or higher also capture much of the substance. DIY filtration systems using a box fan, cardboard, tape, and pleated air filters have been shown to reduce particulate matter. Parents should avoid high congestion areas and stay indoors during heavy wildfire smoke.
“There is not going to be change if people are not aware and lobbying for it, but policy change takes a long time and there are things we can do to protect ourselves,” Wright said.
