Prenatal exposure to phthalates, a chemical commonly found in plastics, has been linked to language delay in toddlers, according to a University public health study. 

The study found that some of the children studied experienced delays in language development at age 3. The researchers found that higher exposure to these plastic chemicals, phthalates, during pregnancy led to a higher probability of language delay. Boys were twice as likely to experience delays due to phthalate’s higher level of intervention with male hormones. 

Phthalates can be found in food storage containers, vinyl flooring, detergent and personal care products such as nail polish, among other things, according to the Centers for Disease Control and Prevention. The seemingly constant exposure we have to these plastic compounds has given them the name “everywhere chemicals” by the scientific community.

Prior studies on phthalates have shown that these chemicals can affect reproductive organs, semen production and genitalia differences in newborns. Associate professor Ruby Nguyen in the University’s School of Public Health wanted to see how phthalates interact with hormones in the developing brain, and how this may be detrimental to growing children. The study followed two groups of children, one in Sweden and the other in the United States, and their mothers starting during pregnancy. 

“We have this thing called ‘critical windows,’ which are periods in our development or our biology that are more sensitive to bad exposures.” Nguyen said. 

The study was mainly focused on the first trimester of pregnancy, because a lot of prenatal development occurs during this time. Nguyen wanted to find the link between exposure during these critical windows and language development. 

“The biggest surprise in this study was the consistency in our findings,” Nguyen said, citing the similarity in findings between both the Swedish and American mothers and children. 

In both the Swedish and American groups, the mothers took urine tests to determine the level of phthalate exposure they had that could be passed onto their children in utero. When the children turned 3 years old, the mothers were asked to estimate how many words their children could speak. If the children spoke less than 50 words at this time, they were considered language delayed. Researchers then compared the level of phthalate exposure in each mother to their child’s language development.

Stacey Moe, the study coordinator for the United States study group, said the children and mothers she sees make the work easy. “They really are why we’re doing what we’re doing.”

Nguyen said reducing exposure to phthalates can be difficult to avoid due to how frequently we come into contact with them. Being cognizant of their presence is the first step to reducing exposure to the chemical. Buying higher quality plastic products and throwing away old products that are wearing down can also help. 

“This is not all doom and gloom,” Nguyen said. “In identifying a child who has a language delay, it allows us as clinicians and public health practitioners a chance to intervene and change their course.”