Whether you’ve heard of phthalates or not, there’s no doubt you’ve been exposed to them. The group of chemicals, known as “plasticizers,” are found nearly everywhere: raincoats, detergents, soaps, shampoos, hair sprays, nail polishes, and the list goes on.

In the past, prenatal exposure to phthalates has been associated with a risk of lower IQ, childhood asthma, and mental and motor development problems in preschool children. Most recently, the household chemical has been associated with impaired thyroid function among young girls, according to a Columbia University study.

In the study, published in the journal Environment International, researchers measured five types of phthalates and two thyroid hormones in more than 200 pregnant women and their children at age 3. After analyzing the data, it was found that young girls with lower levels of a thyroid hormone, called FT4, was associated with four different phthalates.

Read: The Problem With Phthalates: Fast Food May Expose You To Harmful Industrial Chemicals

“Parents with young children should avoid using products containing phthalates such as shampoos, nail polish, and vinyl flooring,” senior author Pam Factor-Litvak said in a news release.  

The thyroid may be small, but it plays a large role in the function of some of the body’s most important organs, including the brain. Hormones produced by the thyroid work on a schedule, and if timing is off, it may lead to problems in the brain, explained Factor-Litvak.

“The thyroid disruptions we see in this study, although they fall within the normal range, could explain some of the cognitive problems we see in children exposed to phthalates and we are currently investigating that,” she said. “As we know from lead, even small exposures can make a big difference.”

Read: Diabetes And Obesity Epidemic May Be Caused By Environmental Chemicals, Like BPA And Phthalates

A connection between phthalate exposure and an impaired thyroid was only found in girls, not boys. This might be due to the fact females are more likely than males to have thyroid problems; therefore, they’re more vulnerable to chemicals that affect it, the researchers explain. About 1 in 8 women will have a thyroid problem during her lifetime, according to the United States Office on Women’s Health. Thyroid diseases can cause a range of complications, including issues with your menstrual period, problems getting pregnant, and trouble during pregnancy.

“Going forward, it’s important to learn what phthalates do to harm children, as well as the route by which this harm is inflicted,” Factor-Litvak said. “Our overarching goal is to protect the health of future generations.”

Phthalates are used to make plastics more flexible and harder to break, according to the Centers for Disease Control and Prevention. You can be exposed to them by eating or drinking foods that have been in contact with containers containing the chemical. Additionally, you can be exposed through breathing in air containing vapors or dust contaminated by the chemicals.

See also: Despite A Federal Ban On Phthalates, Widespread Exposure To These Chemicals Still Exists

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