Everyone knows it‘s a good idea to limit the total time spent in heavily polluted areas, or, if that‘s not possible, at least wear a protective mask – such as those currently popular in cities like Tokyo and Hong Kong – thereby decreasing exposure to dangerous air-borne toxins.
When it comes to a certain type of pollutants, called phthalates, however, covering our faces might not always be enough – a new study, published in the journal Environmental Health Perspective, suggests our skin may be capable of absorbing as much of these noxious substances as our lungs.
Phthalates are a group of “semi-volatile” oil-derived chemicals that are used to make plastic soft and flexible, or as dissolving agents for other types of materials, and are found in all kinds of cosmetics, fragrances, and household cleaners.
Even though, over the past 50 years, they’ve become the most widely used “plasticisers” in the world, with around 2 million tonnes produced globally every year, some of the 20 types of these chemicals available today have been recently banned in Europe and the US due to concerns over the damaging effects they might have to our health through prolonged exposure.
Classified as endocrine disruptors, these chemicals have already been implicated in the increased occurrence of asthma, childhood allergies, and potentially even breast cancer, although more research is needed to confirm the latter.
To find out how well these pollutants are absorbed via the skin, lead researcher John Kissel and his colleagues recruited six healthy male participants, and then exposed them to elevated air concentrations of two types of phthalates: diethyl phthalate (DEP) and di(n-butyl) phthalate DnBP.
First, the volunteers were protected from inhaling the chemical by wearing specialised “breathing hoods” (which look a bit like spacesuit helmets from a campy science fiction movie of the 50s), and then exposed to it without them the following week.
“Metabolite concentrations were lower when the participants were exposed to chamber air while wearing a hood, but the levels were still substantially higher than levels measured before the participants entered the chamber, indicating significant uptake of DEP and DnBP while participants were wearing a hood,” wrote the authors in their paper.
Results showed that dermal uptake of DEP is about 10 percent, and DnBP 82 percent, higher than their inhalation intake. Participant age was also found to be significant. “The uptake of DEP by the 66-year-old is five times greater than that of the 27-year-old, while the uptake of DnBP is seven times greater.”
Despite the small sample size and somewhat artificial study conditions (e.g., the subjects were allowed to only wear shorts), these findings, especially when coupled with earlier research, which indicates that phthalate levels may build up in our bodies over many years, is certainly a cause for concern.
“[I]f the whole body is exposed, then even low rates of exposure can deliver what turns out to be nontrivial amounts of these chemicals,” said Kissel.