New research suggests that chemicals found in plastics and cosmetics, which can disrupt hormones, may be responsible for nearly 56,000 preterm births in the U.S. in 2018. The research team arrived at this number by analyzing data from over 5,000 pregnant women in the U.S.
The study found that phthalates, which are commonly used in food packaging as well as personal care products like nail polishes and hair sprays, are associated with an increased risk of premature birth and lower birth weight. The research also found that the concentration of phthalate breakdown products in the mother’s urine is linked to the likelihood of these pregnancy outcomes, but the study did not directly prove that these chemicals caused preterm births.
The report notes that the observed changes in the timing of births were on a small scale of days, but the consequences of a shortened pregnancy can be significant. A normal human pregnancy lasts about 40 weeks; however, births that occur before 37 weeks are considered preterm. Dr. Leonardo Trasande, lead author of the study and a pediatrics professor at NYU Langone Health, emphasized that even shortening gestation from 40 weeks to 37 can have severe cognitive consequences, as well as additional health care and other related costs.
He explained that even a slight change in the population of people delivering babies could lead to a significant increase in the number of preterm births. According to a new study published in The Lancet Planetary Health, this could result in additional medical costs and lost economic productivity of up to $8.1 billion over the lifetimes of 56,000 children. Previous research has indicated that exposure to phthalates can cause inflammation and hormonal disruptions, especially with regard to reproduction, and has been linked to obesity, cancer, and infertility in humans. Phthalates can be ingested by consuming food that has come into contact with phthalate-containing products or by inhaling chemicals from the air. The liver metabolizes phthalates into metabolites, which are then excreted in urine. While previous research has suggested that phthalates may contribute to preterm birth, it was limited in scope and did not include diverse populations or newer versions of these chemicals.
The new study drew data from women who participated in the National Institutes of Health’s Environmental Influences on Child Health Outcomes (ECHO) Program between 1998 and 2022. The study evaluated the levels of 20 phthalate metabolites in urine samples taken from the women during three different stages of pregnancy. The researchers then compared these levels to the newborns’ birth weight and age at birth, as well as other potentially influential factors such as the mother’s ethnicity and age.
The concentration of phthalate byproducts in the women’s urine remained consistent across all trimesters. The most common phthalates were mono-ethyl phthalate, which is found in products such as soap and perfume, and phthalic acid, which is used to produce polyester. Women in the bottom 10% of exposure to each chemical did not face any increased risk of preterm birth, while those in the top 10% had a significantly higher chance of preterm birth. For example, women in the top 10% with the highest exposure levels to Di-2-ethylhexyl phthalate (DEHP) had a 45% greater risk of preterm birth than those with the lowest levels of the chemical.
Based on phthalate exposure modeling studies and published birth data, the research team estimated that up to 56,000 preterm births in 2018 may have been related to phthalates. However, the study’s findings may be biased due to several limitations of the data, such as the urine samples not being a perfect reflection of exposure levels in the body, as they only capture a snapshot of what has already been metabolized. Additionally, it is possible that the women were exposed to other types of phthalates that the researchers did not examine.
Nevertheless, “this important study shows how ubiquitous chemicals, such as phthalates, can have adverse health effects,” Dr. Sophie Balk, a professor of pediatrics at the Albert Einstein College of Medicine and a pediatrician at the Children’s Hospital at Montefiore who was not involved in the study, told Live Science in an email.
Unfortunately, it is often up to consumers to determine which products could contain phthalates and other potentially concerning chemicals, because that level of labeling is not required by federal law, she said.
“Some phthalates have been banned from children’s toys and other children’s items, but phthalates are still widely used in many personal care products and food packaging,” Balk said. People wishing to limit exposure could consider avoiding products that contain the words “fragrance” or “parfum” in their ingredients, choosing fresh foods over packaged ones and avoiding microwaving food in plastic containers, she said.
