Using styling products to groom hair and applying heat to keep it in check has become an everyday ritual for many. But, maybe it's time to reconsider the choices. A new study has revealed that hair styling products, when used with heating tools, could emit chemicals that are harmful to both health and the environment.

Purdue University researchers found that several chemicals such as volatile organic compounds (VOCs), including cyclic volatile methyl siloxanes, found commonly in hair care products can linger in the air after use. A single hair styling session inside a closed room could result in inhalation of 1-17 milligrams of potentially harmful chemicals, the study revealed.

The study was published in Environmental Science and Technology, a journal of the American Chemical Society (ACS).

"We found the results to be extremely alarming. We did not expect to see such significant emissions of volatile chemical mixtures from off-the-shelf hair care products during typical hair care routines that many people perform each and every day," study author Nusrat Jung, an assistant professor at the Lyles School of Civil Engineering, said in a news release.

The most concerning chemical inhaled is decamethylcyclopentasiloxane (D5 siloxane), one of the most common and abundantly used ingredients due to its properties such as low surface tension, inertness, high thermal stability and ability to provide a smooth texture.

"D5 siloxane has been found to lead to adverse effects on the respiratory tract, liver and nervous system of laboratory animals. The use of the chemical in wash-off cosmetic products has already been restricted in the European Union because of this. Many of these products are scented, too, and some of the chemicals used to make these fragrances are potentially dangerous to inhale as well," Jung said.

Although the results of D5 siloxane in animal studies are concerning, there is little information on its human impact when inhaled for a long period, Jung added.

Previous studies have looked into the amounts of siloxanes released from personal care "wash-off" products like shampoos and skin cleansers. However, the nature of the chemical release associated with "leave-on" products like hair gels, oils, creams, waxes and sprays was not examined. Also, they did not analyze real-time changes in indoor air composition associated with styling hair.

The team behind the latest study examined the real-time emissions of VOCs, including cyclic volatile methyl siloxanes (cVMS), in small bathrooms where they are typically applied.

The results showed that the emissions were affected by factors like the type of styling product, length of hair and temperature of the styling tool. Longer hair and the higher temperature of the styling tool caused higher emissions.

"When met with temperatures of 210 degrees Celsius, researchers found the chemical emissions from the hair care products increased anywhere from 50% to 310%," the researchers wrote.

The chemicals released did not just remain in the room but spread to other rooms of the house and even affected the outdoor air quality.

According to surveys conducted among different populations, 16% to 70% of participants use leave-on hair care or hair styling products. The average use of hair care products is between two and five times per week.

Based on this data, and the assumption that 10% of leave-on hair care products are siloxane-based, researchers estimate that total indoor-to-outdoor emission of D5 could reach 0.4 to 6 metric tons per year in the U.S.

"The best solution is to simply not use these products. I used to use similar products myself to straighten my hair, but after we analyzed the data, it became immediately clear that the best thing I could do to protect my own health was to stop using them," Jung said.

If someone needs to use the products, keep an exhaust fan running in the room to minimize the amount of chemicals inhaled, said Jinglin Jiang, another researcher.

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