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Common household chemicals linked to childhood language delays, study finds

The substances are used in many products, including floor tiles, personal-care goods and toys.


Prenatal exposure to phthalates – chemicals found in many everyday items, including floor tiles, food packaging, personal-care products, even toys – has been linked to language delays in young children, according to an article published this week in the Journal of the American Medical Association Pediatrics.

The findings are the work of researchers in Sweden as well as the United States, including Rutgers University's School of Public Health and the Icahn School of Medicine at Mount Sinai in New York City.

While prior research raised concerns about the substances' impact on child neurodevelopment and other health issues, the companion Swedish and American studies are believed to shed new light on the chemicals' potential for adverse impacts on early childhood speech development.

The studies involved nearly 965 Swedish expectant mothers and 370 U.S. mothers-to-be who gave urine samples during the first trimester of pregnancy. The samples tested for phthalates, a family of substances used to make plastics more flexible and durable, which are known to enter the environment and can be found in the air, food, and water. Phthalates can also be detected in blood, breast milk, and even amniotic fluid.

When the U.S. children in the study were about 37 months old and the Swedish children were about 30 months old, their mothers were asked how many words their offspring used. Use of less than 50 words was considered a language delay.

Both studies found that about 10 percent of the children used 50 words or fewer, and nearly 3 percent understood fewer than 25 words. Two types of phthalates, dibutyl phthalate and butyl benzyl phthalate, were particularly linked to the verbal delays. Levels of two types of phthalates were found in higher concentrations in those mothers.

"Delays in language development are important because they may be early signals of academic issues and a need for special services later in childhood," said Emily Barrett, an associate professor at the Rutgers School of Public Health who took part in the study.

"This adds to the growing body of work suggesting that phthalates may be harmful to the developing fetus, and suggests that we may need tighter regulations of these chemicals in the everyday products we use," said Barrett.

Barrett said the research found that "virtually 100 percent of people studied have measurable levels of these chemicals in their bodies."

"Given the prevalence of prenatal exposure to these chemicals and the importance of language development, pregnant women should reduce their exposure to phthalates by choosing scent-free personal-care products and phthalate-free nail polish," said study senior author Shanna Swan, professor of environmental and public health at the Icahn School of Medicine.

However, Swan also noted these chemicals are hard to avoid.

Phthalates, Swan said, "are hidden in many household products, like vinyl floor covering and upholstery, and are hard to avoid, since there is no labeling of ingredients in these products."

The researchers said their findings, published Monday, suggest more investigation into the link between these common chemicals and language delays may be warranted. They plan to follow the children they tested and re-examine their language development when they are 6 to 7 years old.