Research Brief: Exposure to chemical in many plastics linked to language delay in toddlers

Mom and baby

Phthalates, compounds that make plastics soft and flexible, are often called “everywhere chemicals” because they are so common in the environment. A new study involving University of Minnesota School of Public Health researchers, recently published in the journal JAMA Pediatrics, discovered that prenatal phthalate exposure can disrupt the hormone systems in people, leading to physical abnormalities and altered brain functioning, such as language development delays.

The researchers discovered the link by looking at the language development of 1,333 participants from two child development studies — one from Sweden and the other from the United States.

In both studies, pregnant mothers were given urine tests to measure the amounts and types of phthalates in their bodies during gestation. After their children were born, the mothers were asked to estimate how many words their child spoke at approximately age three. The possible responses were “fewer than 25 words,” “25 to 50 words,” and “more than 50 words.” Any responses of 50 words or fewer were classified as language delayed. The researchers then looked at how the phthalate levels in the mothers tracked with the language scores of their children.

Overall, the study found that:

  • 233 children were classified as language delayed.
  • exposure to two particular phthalates, dibutyl phthalate and butyl benzyl phthalate, were associated with an increased risk of language delay of 20-40 percent.
  • boys had nearly double the rates of language delay compared to girls (phthalates are believed to interfere with male hormones in particular).
  • there was evidence of a dose-response: children exposed to higher levels of phthalate in utero were more likely to be language delayed.

Study researcher and Associate Professor Ruby Nguyen, who leads The Infant Development and Environmental Study (TIDES) site at the University of Minnesota, said the dose response and other results provide strong evidence that the risks of phthalates are real. The findings also support an additional investigation and new policy action such as government restrictions on certain chemicals.

“We need to continue to work with other researchers, health providers and policymakers to identify children at high risk for development delays due to phthalate exposure,” said Nguyen. “More education in and around the time of pregnancy about the risks of phthalates and other endocrine-disrupting chemicals is also warranted.”

Nguyen is continuing her research with the study by looking at how phthalates and other chemicals influence many health outcomes, including the cardiovascular and lung development of children.


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