Children may suffer delayed language skills if their mothers come in contact with common chemicals called phthalates in early pregnancy, new research suggests.
Phthalates are in countless products from nail polish and hair spray to food packaging and vinyl flooring. As plasticizers, they make things more pliable; as solvents, they enable other substances to dissolve.
Phthalates hormonally active
In the new study, researchers found that the risk for language delay at about age three years was up to 30% higher among children whose mothers had higher exposure to two phthalates in particular: dibutyl phthalate (DBP) and butyl benzyl phthalate (BBP). Both chemicals are in products such as older vinyl flooring, cosmetics and plastic toys.
"Phthalates are known to be hormonally active and affect the body's hormone system," said researcher Shanna Swan, a professor of environmental and public health at the Icahn School of Medicine at Mount Sinai in New York City.
Although the study cannot prove these chemicals cause delays in language development, Swan believes there is good reason to think they do.
Both DBP and BBP have been shown to lower testosterone in the mother during early pregnancy, Swan said. That helps explain how they can affect intellectual development, she noted.
Phthalates previously have been linked to developmental delays, lower IQ and underdeveloped male sex organs, the researchers said.
Because they are so commonplace, "we are all exposed all the time," said lead researcher Carl-Gustaf Bornehag, a professor at Karlstad University in Sweden.
Phthalates leach into the air
DBP and BBP are banned in many products, but they have very long life cycles. For example, vinyl flooring can be used for 20 to 30 years, meaning people are exposed for a very long time, he said.
Also, phthalates are routinely detected in indoor air, dust, food and water because they leach into the air, according to background notes with the study.
Swan said the only way to avoid these chemicals is to buy products labelled phthalate-free or to carefully read label ingredients.
However, steering clear of the chemicals is easier said than done, Bornehag pointed out.
"It is often hard to get information about chemicals in products and articles, which makes it difficult to avoid exposure. We need better labelling systems," he said.
And Swan added that banned phthalates have been replaced by similarly troublesome chemicals.
"Manufacturers have taken out the worst offenders and put in a slight change, which changes its name, but they are equally hormonally active," she said. "There have been some substitutions."
According to Steven Gilbert, director of the Institute of Neurotoxicology and Neurological Disorders, in Seattle, the real issue is that chemicals put into everyday household products are not regulated.
They're only tested and potentially banned when a problem arises after years of use, he said.
"What we need to do is change the laws," Gilbert said. "We've shown that these are bad actors and they cause cell changes, and we just need to stop using them."
Boys more affected than girls
The study involved pregnant women and their children who took part in long-term studies in Sweden or the United States. Nearly 1 000 mothers were in Sweden; 370 were in the United States.
Parents were asked about how many words their kids understood at about 30 months to 37 months of age. Children who understood 50 or fewer words were said to have a language delay.
Overall, 10% had a language delay, boys more often than girls, the researchers found.
Urine samples collected from the mothers in the 10th week of pregnancy revealed a correlation between phthalate exposure and language delay, according to the study.
The researchers said the results were statistically significant in the Swedish study, but not in the US study. They believe the difference is probably due to the US study's smaller sample size.
The report was published online in JAMA Pediatrics.
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