Study connects common chemicals to preterm births, other health risks

A large study of chemical exposures during pregnancy has found that pregnant women are exposed to dozens of chemicals everyday, many of which are linked to preterm births and low birth weights. 

The chemicals showed up in a vast array of products, highlighting the massive scope of exposure for expecting mothers, as well as their potential health risks.

The study, published in JAMA Network Open included more than 5,000 pairs of mothers and children across the country born between 2000 and 2021. In what’s considered to be one of the largest studies of chemical exposures during pregnancy, data was collected based on chemicals found in maternal urine samples, as well as pregnancy duration and birth weight.

Researchers at Stanford University and the University of North Carolina at Chapel Hill looked at chemicals commonly found in everyday products, including phthalates, replacement plasticizers, polycyclic aromatic hydrocarbons (PAHs) and halogenated phenols. Of the 113 different chemicals that were tested, an average of 45 were present in each sample. The maximum amount of chemicals observed for a single sample was 64. 

“The fact that some of the participants in our study had 64 chemicals detected in their samples, that was sort of surprising to me, that’s a lot of chemicals,” said Jessie Buckley, professor of epidemiology at the University of North Carolina at Chapel Hill and lead author of the study. 

Buckley noted that many of the chemicals were found in products that people can’t necessarily avoid.

 “A lot of the chemicals that we looked at are found in so many common and everyday products, things like personal care products, fragrances, plastics. We looked at a lot of pesticides, so that can be found in foods as well,” she said. 

The fact that many of the chemicals are associated with low birth weights and preterm births is concerning, said Tracey Woodruff, professor of epidemiology and population health at Stanford and co-author of the study. 

“If a child is born too small or too early, it’s an indicator of increased risk for a number of different adverse child health outcomes and even adult adverse adult health outcomes,” said  Woodruff. Early on, preterm birth and low birth weight can increase the risk of infant mortality, she said, adding that in adults, it can lead to an increased risk of cardiovascular events.

The findings were “sobering,” said Shelley Liu, associate professor at the Icahn School of Medicine at Mount Sinai, who was not involved in the study. “This unfortunately shows how ubiquitous these chemicals are in daily life,” she wrote in an email.

Hard to avoid

While people have some control over the chemicals they’re exposed to, Buckley noted that there’s only so much someone can do. 

“We always like to remind people that changes in product safety and environmental protections are the best way to protect most of us from exposures,” noting “a lot of things aren’t labeled, so you don’t always know that a product has a chemical in it.”

Last year, the Environmental Protection Agency (EPA) announced it would regulate five major phthalates due to the risk to workers in specific industrial settings and to the environment, citing “hormone deficiencies and endocrine disruption.” However, the EPA also said it found “no products with exposure levels that are causing unreasonable risk to the general population.”

“This unfortunately shows how ubiquitous these chemicals are in daily life.” – Shelley Liu, Icahn School of Medicine at Mount Sinai

At the time, the agency said that under the Toxic Substances Control Act, the EPA did not analyze exposures from food, food additives, food packaging, medical devices, cosmetics and other consumer products that are under the purview of the Food and Drug Administration or Consumer Product Safety Commission.

In 2017, the Consumer Product Safety Commission (CPSC) finalized a rule adding five specific phthalates to a list of restricted chemicals in children’s toys and childcare products. However, the list did not include products used during pregnancy.

Interestingly enough, researchers identified plasticizers that were recently introduced to replace toxic chemicals like phthalates. However, they found that the newer substances had similar health effects to the chemicals they replaced.

“They might have the same property that manufacturers want, but it also means they may have the same properties that make them bad for health,” said Buckley.

“Unfortunately this is a common, known phenomenon called ‘regrettable substitution,’ in which one toxic compound is phased out of use by industry but replaced by another compound that exerts similar health impacts,” Liu wrote.

Researchers believe that this study highlights the importance for both governments and companies to reduce harmful chemicals in everyday products while ensuring new chemicals are safe.

“This provides a really valuable data set for the government to understand the long term health implications of these chemical exposures,” said Woodruff, who hopes the EPA will consider this study in future risk evaluations, adding, “It will leave pregnant women at risk if they don’t.”

Featured image: Eduardo Ramos for Unsplash+