Harmful Chemical D5 Found in Common Hair Care Products

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Harmful Chemical D5 Found in Common Hair Care Products

Health Hazards in the Bathroom: Harmful Chemical D5 Found in Common Hair Care Products

A study conducted by Purdue University reveals potential health risks associated with daily hair care routines, particularly the presence of harmful chemicals, including Decamethylcyclopentasiloxane (D5), in many hair care products.

This exposure poses unknown long-term health risks and contributes to environmental pollution, especially in urban areas.

The research suggests avoiding the use of these products or employing ventilation systems to reduce exposure, emphasizing the need for further research and potential regulation.

Harmful Chemical D5 Found in Common Hair Care Products

Purdue University researchers found that the average person inhales several milligrams of potentially harmful chemicals during their daily hair care routines.

In a recent paper published in the journal “Environmental Science & Technology” by the American Chemical Society (ACS), Assistant Professor Nusrat Jung from the Lyles School of Civil Engineering at Purdue University discovered that various chemicals, particularly cyclic volatile methylsiloxanes prevalent in hair care products, linger in the air after use. Jung’s team reports that, on average, a single hair care session at home can result in inhaling 1-17 milligrams of potential harmful chemicals.

“We were surprised by the results,” says Jung. “We didn’t anticipate that off-the-shelf hair care products used in typical daily routines by many people would emit such significant amounts of volatile chemical compounds.”

According to Jung, one of the most inhaled and concerning chemicals is Decamethylcyclopentasiloxane, also known as D5. It is an organosilicon compound commonly listed as one of the top ingredients in many hair care products, indicating it may be one of the highest concentration components. D5 has been found to have adverse effects on the respiratory system, liver, and nervous system in experimental animals. Consequently, the European Union has restricted its use in rinse-off cosmetics. Many such products also contain fragrances, and some chemicals used to produce these fragrances pose potential dangers when inhaled.

In a residential construction engineering lab at Purdue University, researchers studied how various hair care products release residual chemicals into the air.

According to the European Chemicals Agency, D5 is classified as a “very persistent and very bioaccumulative” substance. While testing results on laboratory animals are concerning, information about its impact on the human body is limited.

Jung says, “There’s not much in-depth research on this, so we really don’t know the extent of the threat from long-term inhalation of these chemicals. We’ve tested ‘rinse-off’ products like shampoos, but ‘leave-on’ products like hair gel, oil, lotion, and spray have been scarcely tested.”

Jung’s research also indicates that heating these chemicals through devices like curling irons and straighteners further releases them into the air. When the temperature reaches 210 degrees Celsius, the researchers found that the chemical emissions from hair care products increased by 50% to 310%. Worse still, these airborne chemicals don’t stay confined to one room; they can spread beyond homes.

“Home ventilation may be a primary pathway for the migration of siloxanes from indoor to outdoor environments,” Jung says. “This is particularly significant in urban environments, as hundreds of families can collectively release potential harmful chemicals into the city atmosphere in a short period as they get ready for work and school in the morning. These chemicals then re-enter buildings through ventilation systems. So, even if using products with harmful chemicals is not part of your daily hair care routine, you’re still impacted by the surrounding urban environment.”

The research report indicates that 16% to 70% of participants in surveys used leave-in hair care or styling products. Based on the survey’s patterns of hair care product use, the average frequency of use is 2 to 5 times per week. Assuming that 10% of leave-in hair care products use siloxanes, the total indoor-to-outdoor emissions of D5 in the United States could range from 0.4 to 6 metric tons annually.

So, how can people protect themselves from inhaling these chemicals?

“The best solution is to refrain from using these products altogether,” says Jung. “I used similar products myself to straighten my hair in the past, but after analyzing the data, I immediately realized that the best way to protect one’s health is to stop using these products.”

Jinglin Jiang, a Ph.D. student and researcher in civil engineering at Purdue University, suggests that if one must use these products, the best approach is to keep the exhaust fan running to minimize inhalation of chemicals: “Ventilation is an effective method to reduce exposure to siloxanes during indoor hair care processes. Our models show that turning on the bathroom exhaust fan can reduce D5 inhalation exposure by over 90%.”

However, this exacerbates its impact on the environment. The research report indicates that with the exhaust fan consistently turned off, indoor and outdoor D5 emissions accumulate to 710 milligrams within three hours, whereas with the fan always on, the indoor and outdoor D5 emissions reach 900 milligrams within just one hour.

Jung says, “It makes sense that some regions in the world restrict the use of these chemicals in hair care products. Further research is indeed needed to understand the impact on humans and the Earth, and regulatory measures should be considered.”

Jung’s experimental research was conducted in the Zero-Energy Design Guide (zEDGE) small house, a mechanically ventilated, single-zone residential building with air conditioning. The lab used the state-of-the-art Proton Transfer Reaction Time-of-Flight Mass Spectrometer (PTR-TOF-MS) to measure indoor air concentrations of D5 siloxane and other volatile chemicals in real-time.

The routine hair care emission experiments took place within zEDGE, lasting for several months and including three types of experiments: simulated hair care experiments (replicating actual hair care routines in a home environment), hotplate emission experiments (exploring the relationship between the temperature of hair care tools and emissions of volatile organic compounds), and surface area emission experiments (studying how hair surface area affects emissions of volatile organic compounds during hair care activities).

In realistic hair care procedure emission experiments, participants were asked to bring their own hair care products and styling tools to replicate their hair care routines in zEDGE. Before each experiment, participants were instructed to divide their hair into four sections. The length of each participant’s hair was categorized as long (below the shoulders) or short (above the shoulders). Each experiment consisted of four phases to simulate daily activities in real life.

After styling their hair, participants had two minutes to clean up their tools and leave zEDGE. This was followed by a 60-minute concentration decay period during which zEDGE was idle, and the high-resolution PTR-TOF-MS monitored the decay of indoor concentrations of volatile organic compounds. The focus of the experiments and subsequent analysis was on indoor concentrations and emissions of volatile organic compounds during and after routine hair care activities.