In the first study of its kind, researchers from the Icahn School of Medicine at Mount Sinai and Karlstad University in Sweden have found an elevated rate of language delay in children at 30 months old who were born to mothers exposed to phthalates—synthetic chemicals found in common household items and personal care products.

The study, the first to examine early language development in relation to first-trimester phthalate exposure as measured in urine levels, will be published online October 29 in JAMA Pediatrics.

The Swedish Environmental Longitudinal, Mother and Child, Asthma and Allergy study (SELMA) in Sweden and The Infant Development and the Environment Study (TIDES) in the United States provided data for the research.

Information was gathered from 963 pregnant women and their children from the Swedish study and 370 women and their children from the US study. Parents were asked how many words their children understood at 30 months in SELMA and at 37 months in TIDES. Ten percent of children in both studies experienced language delay, with higher rates in boys than in girls. Children who understood fewer than 50 words were classified with language delay. Phthalate levels were measured in urine samples obtained from the women at median 10th week of pregnancy in both cohorts. The risk for language delay was higher by up to 30% in children whose mothers had doubled exposure levels of two chemicals: dibutyl phthalate (DBP) and butyl benzyl phthalate (BBP), both of which are commonly found in household products, including older vinyl flooring, cosmetics, and plastic toys.

Before statistical adjustment, results were statistically significant in both studies. After adjusting for potential confounders, results were significant in the Swedish study, but not in the US study, likely due to its smaller sample size.

“Given the prevalence of prenatal exposure to these chemicals and the importance of language development, pregnant women should try to reduce their exposure to phthalates by choosing scent-free personal care products and phthalate-free nail polish,” said the study’s senior author, Shanna Swan, PhD, professor of environmental and public health at the Icahn School of Medicine at Mount Sinai. “However, these phthalates are hidden in many household products like older vinyl floor covering and upholstery and are hard to avoid since there is no labeling of ingredients in these products.”

“We were surprised by how similar the results were between the two very different populations in Sweden and the US,” said principal investigator Carl-Gustaf Bornehag, PhD, Professor, Karlstad University, Sweden and adjunct professor at Icahn School of Medicine at Mount Sinai. “It’s important for us to look at language development because it has shown to be predictive of other neurodevelopmental problems in children.”

The SELMA and TIDES studies will follow the children and re-examine language development at 7 and 6 years, respectively.

—Newswise