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American engineers from Purdue University’s research has found, that thermal hair styling contributes to the release of billions of nanoparticles that directly settle in the lungs.
A team of researchers, led by a researcher from the Lyles School of Civil Engineering Nusrat Jung and graduate students Jianhui Liu found, that 10-20 minutes of hair care, using heat exposes, a person to more than 10 billion nanoparticles that settle in the lungs.These nanoparticles can lead to problems such as respiratory stress, pneumonia, and cognitive decline.
“This is indeed a serious concern. The amount of nanoparticles inhaled when using conventional commercially available hair care products was much higher than we ever thought”, — Nusrat Jung says.
According to him, this is the first study, that measured the number of nanoparticles, formed by when styling hair with heat. The researchers studied temporary changes in the concentration and size distribution of nanoparticles in the room during hair styling procedures using heating.
“By providing a detailed characterization of indoor nanoparticle emissions during personal care procedures, our study lays the groundwork for future research on their impact on indoor air chemistry and inhalation toxicity. Studies of this kind have never been conducted before, so until now, the public knew little about the potential health risks associated with everyday hair care”, — Nusrat Jung emphasized.
As noted by Jianhui Liu, hair care products become extremely harmful, when exposed to heat from styling appliances, such as curling irons and straighteners. At temperatures above 150°C, chemical compounds not only quickly get into the air, but also lead to the formation of new nanoparticles.
“The formation of atmospheric nanoparticles is particularly sensitive to such thermal effects. Heat is the main factor: cyclic siloxanes and other small ingredients evaporate, form germs, and turn into new nanoparticles, most of which are less than 100 nanometers in size”, — explains Jianhui Liu.
Pros research resultsheld in 2023, Nusrat Jung and a team of researchers found, that heat significantly increases emissions of volatile chemicals, among other things, decamethylcyclopentasiloxane (also known as D5-siloxane). D5-siloxane has been identified as a substance of concern by inhalation.
“When we first studied the emissions of hair care products, during heat waves, we focused on the volatile chemicals that were released, and what we found was already alarming. But when we looked even more closely at the situation, using aerosol measurement instruments, commonly used to measure exhaust emissions, we found that these chemicals were generating emissions with a concentration of 10,000 to 100,000 nanoparticles per cubic centimeter”, — Nusrat Jung said.
The head of the study explains that D5-siloxane is an organosilicon compound that is used in the vast majority of cases is indicated in the first or second place in the composition of many hair care products. Over the past few decades, it has become a common ingredient in many personal care products due to its low surface tension, inertness, high heat resistance, and smooth texture.
According to the European Chemicals Agency, Siloxane D5 is classified as “very persistent, highly bioaccumulative”. The results of animal studies in the laboratory have demonstrated, that the effects of this chemical compound on human lungs have not been sufficiently studied. For this reason, the use of this chemical in rinse-off cosmetics is already restricted in the European Union.
“Siloxane D5 has been found to have adverse effects on the respiratory tract, liver, and nervous system of laboratory animals”, — Nusrat Jung emphasized.
At high temperatures, cyclic siloxanes and other ingredients in hair care products can evaporate and form large amounts of nanoparticles in the air, which can then settle throughout the respiratory system. These secondary emissions and impacts remain much less well understood than primary chemical emissions.
“And now it turns out, that the danger posed by these products to the air, especially formulations that are resistant to high temperatures, such as hairsprays, creams, and gels, is even higher than we expected”, — Jianhui Liu said.
The results of modeling the deposition of these particles in the respiratory tract have been demonstrated, more than 10 billion nanoparticles can be deposited in the respiratory system during a single hair styling session, with the largest dose occurring in the pulmonary region — the deepest part of the lungs. Thus, styling hair with hot air is a significant source of nanoparticles indoors.
According to Nusrat Jung and Jianhui Liu, the best way to avoid inhaling these harmful nanoparticles is to avoid using hair styling products in combination with heat exposure. In case a person is unable to avoid such procedures, Jung recommends using exhaust fans to improve room ventilation.
Nusrat Jung notes, that future research should focus on measuring the size of these particles using instruments capable of detecting particles as small as 1 nm. In addition, it is necessary to analyze the chemical composition of these nanoparticles.
The study was conducted by in a residential architectural and engineering laboratory. The zEDGE laboratory is a mechanically ventilated residential building consisting of one zone and an air-conditioned room. A state-of-the-art low-pressure, high-resolution electric low-pressure impinger (HR-ELPI+) was used to measure the concentration of nanoparticles in the air in real time with a second accuracy. For real-time monitoring of volatile chemicals, the following was used time-of-flight mass spectrometer with proton transfer reaction (PTR-TOF-MS).
Experiments to investigate emissions from heat-assisted hair care products were conducted over several months. The measurements were divided into 3 types: realistic hair care procedures, hot plate emission experiments, as well as hair surface emission experiments that investigate how hair surface area affects the emission of nanoparticles during hair care procedures.
For realistic experiments to measure emissions from hair care, participants were asked to bring their own hair care products and styling tools. Before each experiment, participants were instructed to part their hair into four strands. The length of each participant’s hair was defined as “long” (below the shoulders) or “short” (above the shoulders). The sequence of each experiment consisted of four periods to mimic a real-life procedure.
After styling their hair, the participants had 2 minutes to gather their belongings and leave the laboratory. Over the next hour, the concentration of nanoparticles in the air decreased. High resolution electric low-pressure impactor monitored the decrease in the concentration of nanoparticles in the room. The experiments and subsequent analysis focused on the formation of nanoparticles and their subsequent effects during and after periods of active hair care.
The results of the study are published in the journal Environmental Science & Technology
Source: Phys.org
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