Living in areas congested with traffic linked to reduced infant birth weight


A study from Oregon State University released on Friday found that traffic jams are linked to lower birth weights in full-term babies born to parents living near heavy traffic areas, such as freeways and freeways.

Although the decrease was relatively small, the researchers say the cumulative effect of stop-and-go traffic on top of baseline air pollution from cars and other environmental contaminants could have significant consequences for the population level, affecting up to 1.3 million babies per year based on location.

The researchers found that birth weight averaged 29 grams, or about 1 ounce, lower for babies in the highest exposure group compared to babies in the lowest exposure.

“We’ve had all these models to predict pollution, but they can’t measure congestion. With 10,000 vehicles on a road, if those 10,000 vehicles stop and go, there’s a lot more pollution coming from cars,” said co-author Perry Hystad, associate professor in the College of Public Health and Science. OSU human resources. . “There are congestion-specific health impacts that are not included in any environmental risk assessment or cost-benefit analysis, and these should start to be included.”

Low birth weight can cause a variety of problems in infants, including respiratory problems and neurological problems, but at the population level, researchers are more interested in long-term effects.

“There is a higher risk of cardiovascular disease, cognitive impacts, premature mortality; a lot of long-term impacts on the course of life,” Hystad said. “It’s not necessarily the acute events that happen during childbirth.”

The study, published in the journal Science Advances, looked at 579,122 full-term births from 2015 to 2016 in Texas and compared maternal addresses with data from the Texas Busiest Roads Database to map proximity to high traffic areas.

Specifically, the researchers looked at “traffic delay,” defined as the total number of person-hours of road delay multiplied by the length of each road segment in buffer distances around maternal residences. Using traffic delay, they were able to calculate congestion emissions to find out the total number of pounds of carbon dioxide emitted by cars in those areas.

After adjusting for socio-demographic factors and environmental co-exposures, the results showed that traffic delay within 500 meters of the maternal residence was associated with a mean decrease in birth weight of 9 grams when comparing most and least exposed groups. Babies born to parents who lived 300 and 100 meters from the roads suffered slightly greater impacts.

To put that into perspective, Hystad said, previous research has shown that maternal smoking causes a decrease in birth weight of about 150 grams, or 5.3 ounces. A mid-term baby born in the United States weighs about 3,300 grams, or 7.3 pounds.

Based on the proximity of roads to residential areas across the country, researchers estimate that 1.3 million babies are born each year in areas close enough to be affected by congestion pollution, or about 27% of all births in the United States.

“A 9 gram decrease on its own is not clinically significant, but it is somewhat of an indicator of biological impacts that are occurring, which will cause some babies to experience a clinically relevant negative impact,” Hystad said. “A lot of times we’ll see that with air pollution – we’ll see a 2-3% increase in certain impacts, like mortality or cardiovascular disease – but when you multiply that by 27% of all births, it becomes translates into substantial potential impact.”

Additionally, the researchers estimate that 260,000 full-term babies each year live in the most exposed areas where they have observed the greatest magnitude of congestion impact.

Now that they can measure congestion, Hystad said, it’s important to include these results in policy and regulatory discussions, especially because the busiest areas tend to be concentrated near socio-economic neighborhoods. economically disadvantaged and disproportionately affect minority populations.

Unlike tailpipe emissions which are largely regulated at the federal level, traffic congestion is an issue that can be addressed through local programs and policies, he said.

“How do you target methods to reduce exposures that occur in very localized areas? It can be as simple as putting up noise barriers or vegetative barriers, or using zoning approaches and saying you can’t build a school or daycare within 500 meters of a highway” , did he declare. “One thing we wanted to be very aware of is that we’re not promoting this idea of, ‘We need bigger highways.’ It won’t solve the problem.”

An upcoming paper from the same research team will dig deeper into socioeconomic and racial disparities in the birthweight impacts of traffic congestion, Hystad said.

Reference: Willis MD, Schrank D, Xu C, et al. A population-based cohort study of traffic congestion and infant growth using connected vehicle data. Science Adv. 2022;8(43):eabp8281. doi:10.1126/sciadv.abp8281

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