‘Extremely alarming’ study finds common hair styling products can release high levels of toxic chemicals linked to infertility when used with straighteners or curling irons

Hair products used daily by millions of women in the US could expose them to a dangerous chemical linked to infertility, a study warns.

Siloxanes are man-made chemicals used in creams, oils and sprays to add shine and smoothness to hair by preventing moisture from getting in or out.

Scientists at Purdue University in Indiana discovered that when used with high temperatures from curling and straightening irons, the siloxane-laden hair products evaporate and release toxins into the air.

Siloxanes, derived from silicone, have been linked to fertility problems, hormonal imbalance and liver damage.

At temperatures of 210 degrees Celsius, researchers found that chemical emissions from the hair care products increased by 50 to more than 300 percent

They conducted a series of experiments in which participants were asked to recreate their hair care and styling routines in a small house intended to mimic the limited space of their bathrooms at home.

Using the products with and without heated tools increased airborne concentrations of a class of volatile chemicals called cyclic volatile methylsiloxanes (cVMS).

When the exhaust fan was turned off, concentrations of volatile chemicals in the air reached 82 milligrams per cubic meter, although turning on the fan purified about 70 percent of the polluted air.

After 20 minutes, people inhaled a total of 17 mg of siloxane.

Animal studies on this class of chemicals have shown this much higher airborne concentrations in the tens of thousands are fatal.

Although the lethal dose in humans is less clear, researchers warned that repeated exposure to these chemicals as part of daily routine could have health effects.

Siloxanes are synthetic relatives of silicones that are ubiquitous in personal care products because they seal the hair or skin to prevent moisture from seeping in or out, creating a superficial slipperiness.

Each study participant was instructed to bring the products they use at home to the tiny house, including hair lotions, sprays, serums, and oils, as well as any hot tools they may use.

The products studied were marketed primarily to women, although they were technically unisex.

The chemicals have also been found in products targeted at men. For example, a Redken cream pomade contains a siloxane known as dimethicone.

The participants then divided their hair into four sections and tested different treatments on each section.

The concentrations of volatile compounds in the air increased each time a product was applied to a strand of hair.

Applying high heat of about 210 degrees Celsius to hair covered in these products worsened the levels of harmful chemical emissions, increasing emissions anywhere from 50 to 310 percent.

Dr. Nusrat Jung, lead author and professor at Purdue’s School of Civil Engineering, said: ‘We found the results extremely alarming.

“We did not expect such significant emissions of volatile chemical mixtures to occur from ready-to-use hair care products during typical hair care routines that many people perform every day.”

Siloxanes easily evaporate into the air to form a gas, a quality scientists call volatility.

An example of another volatile organic compound that evaporates quickly is acetone, which explains nail polish remover’s characteristic pungent odor as it dries.

The chemical’s ability to evaporate quickly without leaving a sticky residue and its lubricating ability to prevent friction between hair strands have made it a staple ingredient in many skin and hair products.

The most concerning chemical they identified is decamethylcyclopentasiloxane (also known as D5 siloxane), which is often first or second on the ingredient lists of many hair care products, indicating that it may be one of the most common ingredients.

Dr. Jung said: ‘D5 siloxane has been found to have adverse effects on the respiratory tract, liver and nervous system of laboratory animals.

‘The use of the chemical in washable cosmetic products has already been restricted in the European Union. Many of these products are also scented, and some of the chemicals used to make these fragrances are potentially dangerous to inhale.”

Another siloxane chemical called D4, which is considered long-lasting and toxic in the environment, is a known endocrine disrupting chemical which has been shown in rat studies to behave similarly to estrogen.

The chemical was found to have increased the weight of the rodents’ uterus and changed the height of the cells that line the tissues in their bodies, which can negatively impact the reproductive organs and contribute to the development of endocrine disorders. For example, conditions such as polycystic ovary syndrome (PCOS).

On average, a person can inhale a total mass of 1 to 17 milligrams of potentially harmful chemicals during a single 20-minute hair styling session.

Turning on the exhaust fan successfully reduces levels of D5 in the air by about 70 percent, and keeping the fan on “speeds up the decay” of the compound in the air.

When the exhaust fan is on, D5 concentrations drop by 95 percent to less than one milligram per cubic meter within 20 minutes of completing the hair care routine.

While helpful in cleaning up the bathroom or, in this case, the tiny house, researchers warned that exhaust fans direct that polluted air to the outside world, polluting more space than just one’s own home.

Dr. Jung said: ‘Home ventilation is likely an important route for the transport of siloxane from indoors to outdoors.

“In urban environments, this is especially important because there are hundreds – even thousands – of homes in a short period of time that are venting potentially harmful chemicals into the urban atmosphere as people get ready for work and school in the morning.”

The chemicals then make their way back into buildings through ventilation systems, Dr. Jung added.

‘So even if using products with harmful chemicals is not part of your hair care routine, you will still be affected by your environment in an urban environment.’

Their findings were published in the journal Environmental sciences and technology.