Study found that emissions from hair and skin products in two cities are nearly equivalent to that of cars during rush hour.
Every morning, millions of people ready themselves for the day by applying hair spray, perfume, cologne, lotions, and deodorants to their bodies. The result is an unmistakable freshly showered and coiffed aroma that fills subway trains, public buses, school hallways, and offices in the mornings, but wears off as the day goes on. But have you ever wondered where those smells go?
This became the unexpected focus of a study conducted by researchers at the University of Colorado. Led by Matthew Coggan, scientists set out to measure urban air quality in two cities, Boulder and Toronto. As Coggan explained in an article for The Conversation, the lab in which the scientists worked had recently invested in new equipment, the goal of which was to measure wood stove emissions during winter months. But they found something unexpected.
"Surprisingly, we noticed a signal that stood out unexpectedly from all the other data. This compound, which we identified as decamethylcyclopentasiloxane (or D5 siloxane), contains silicon, which uniquely differs from the organic compounds we normally detect. By reviewing scientific literature, we learned that pure D5 siloxane is produced mainly as an additive for deodorants and hair care products. On average, people use products that contain a total of about 100-200 milligrams of D5 every day – roughly the weight of half an aspirin tablet."
D5 is a silicone fluid used to give a soft, silky feel to hair products and add mild water repellency. It is a suspected endocrine disruptor and harmful to reproductive systems. When tested on animals, D5 has been found to produce "tumors, endocrine disruption, neurotoxicity (damage to the brain and peripheral nervous system), organ toxicity (non-reproductive) and skin irritation." While some of it washes down the drain when we shower, and some can be found in soil, oceans, and tissues of fish and humans, the vast majority of D5 ends up in the atmosphere. It is most potent first thing in the morning after application, but evaporates over the course of the day.
This is why the scientists were able to track the rise and fall of D5 emissions over a typical day and compare it to benzene, a carcinogenic chemical that's used as a marker for vehicle emissions. They found that D5 was highest between 6 and 7 a.m. and that during the morning rush hour D5 and benzene emissions were almost equal. As the day wore on, however, D5 decreased while benzene stayed high; in other words, people continue driving around the city after their personal care products have worn off.
"We estimate that, on average, the entire population of the city of Boulder emits 3 to 5 kilograms (6 to 11 pounds) of D5 per day, and that their cars emit about 15 kilograms of benzene in vehicle exhaust."
This research aligns with that of another study conducted earlier this year in Los Angeles, which found that volatile organic compounds (VOCs) play a much greater role in polluting urban air than previously thought. VOCs are found in products such as hair spray, air freshener, perfumes, pesticides, glues, and conventional cleaning products.
It's a disturbing revelation to think that the environmental impact of personal care products, which we associate with beauty and feeling good, is anywhere near that of internal combustion engines, commonly associated with dirty pollution. And yet, this is a connection we must make, not only for the sake of our personal health (many of the chemicals in conventional beauty products are known carcinogens and terrible for our bodies), but now also for the air we breathe.
Choose your beauty products carefully. Fortunately there are many great products available that are free from toxic chemicals and safe enough to be edible; you can find these by reading reviews on TreeHugger, shopping at local farmers' markets for handmade products, or visiting EWG's Skin Deep database to measure and compare specific items. You only get one body. Defend it fiercely.