The study, led by researchers at the UNC Gillings School of Global Public Health, Stanford University School of Medicine, and the Woods Institute for the Environment, was published in JAMA Network Open.

Researchers discovered that participants were exposed to an average of 45 different chemicals. These included phthalates, replacement plasticizers, polycyclic aromatic hydrocarbons (PAHs), and halogenated phenols. Such chemicals can be found in food, drinking water, air pollution, personal care products, fragrances, and a variety of household items.

“These chemicals are difficult to avoid because they’re found in a wide range of products we use every day. It can be difficult to know whether products contain them, and even when we do know, we have limited control over exposures,” said first author Jessie Buckley, PhD, professor of epidemiology at the Gillings School. “Although there are some practical steps people can take, reducing harmful chemicals at the source is the most effective way to protect children and families.”

Phthalates and Replacement Chemicals Remain Widespread

Phthalates and replacement plasticizers were among the chemicals identified in the study. These substances are commonly used in products designed for babies and children, including toys, diaper creams, shampoos, and other consumer goods.

In 2017, the United States Consumer Product Safety Commission permanently banned or significantly restricted eight commonly used phthalates in children’s toys and products because exposure to these chemicals can cause harmful health effects. However, those restrictions did not cover many other products that may be used during pregnancy.

The new research detected several phthalates in participants’ samples, including some that have been introduced as replacements for previously restricted chemicals. Researchers also found a range of plasticizer compounds in the urine samples collected during the study.

More Than 5,000 Mother-Child Pairs Studied

The analysis included data from more than 5,000 mothers and their children born between 2000 and 2021. Researchers measured chemicals in maternal urine samples and compared those findings with pregnancy duration and birth weight.

The team tested for 113 chemicals commonly present in homes and in air, food, and water. On average, each sample contained 45 chemicals, while the highest number detected in a single sample was 64. Researchers then evaluated how these exposures were associated with differences in gestational age and birth weight.

Several phthalates and alternative plasticizers were consistently associated with shorter pregnancies. Phthalates, replacement plasticizers, and PAHs were also linked to lower birth weight. In addition, some lesser studied chemicals identified in the research, including halogenated phenols, showed associations with lower birth weight.

The researchers also detected newer plasticizers that were introduced as alternatives to more widely recognized toxic chemicals such as phthalates. However, the study found that these replacement chemicals appeared to have health effects similar to the substances they were intended to replace.

Researchers Call for Stronger Chemical Safety Policies

“Our study highlights the need for stronger policies to protect people from toxic chemicals,” said senior researcher Tracey Woodruff, PhD, professor of epidemiology and population health at Stanford. “For example, we found that several newer chemicals used to replace toxic ones are also harmful, which underscores why new and replacement chemicals must be properly evaluated before they are put on the market. Further, government agencies that evaluate health risks for toxic chemicals like phthalates should incorporate our findings to reduce exposures and ensure healthier pregnancies.”

Buckley said the findings add to a growing body of evidence showing the importance of limiting chemical exposures during pregnancy.

“Our study, along with other similar findings, underscores the importance of reducing chemical exposures that impact pregnancy, as even small changes in birthweight or gestational age can have significant impacts on children’s health,” said Buckley.

Woodruff noted that many sources of exposure are difficult for individuals to control on their own.

“Pregnant people are at risk of chemical exposure through multiple sources, many of them beyond their control,” said Woodruff. “Governments and companies need to do a better job of reducing harmful chemicals in everyday products and ensuring new chemicals are safe, which will lead to healthier children and families.”

Research reported in this publication was supported by the Environmental influences on Child Health Outcomes (ECHO) Program, Office of the Director, National Institutes of Health.