The act of grilling food over an open flame irrevocably changed human evolution many millennia ago, and although new forms of food preparation have cropped up, the method remains popular thanks to beloved summertime (or anytime) tradition of charcoal barbecuing.
Yet like any combustion-based activity, a good ol’ fashioned cookout produces large amounts of carcinogenic molecules known as polycyclic aromatic hydrocarbons (PAHs).
Scientists have known about the dangers of PAHs for some time, and earlier research has shown that both inhaling BBQ smoke and eating the resultant food introduces decent amounts of these chemicals into the body. Yet no one has examined how much the skin, which readily absorbs certain types of molecules, contributes to the overall uptake of PAHs during barbecuing. Until now.
In one of the best recent examples of a study you didn’t know needed to be conducted, researchers from the Peking and Jinan Universities compared the levels of PAH exposure from smoke inhalation, food consumption, and dermal absorption by having 20 male volunteers stand around a cluster of charcoal stoves and channel their inner pitmaster.
Surprisingly, they found that the skin may let more PAHs enter the body than direct fume inhalation.
As described in the journal Environmental Science & Technology, the Chinese team created three groups: Seven men were assigned to eat grilled foods, inhale, and absorb through skin; another seven inhaled and absorbed, and six men were assigned dermal exposure only – they wore sealed masks supplying them fresh air during the 2.5-hour-long barbecuing session.
As expected, urine samples taken over the subsequent 24 hours showed that the highest concentrations of metabolized PAHs came from food ingestion, as calculated by subtracting the results of group one from group two. And although it appears that certain PAHs are more likely to be absorbed through the lungs than the skin and vice versa, overall, dermal absorption yielded greater excreted amounts of metabolized PAHs than inhalation.
The authors hypothesize that lipids present on the skin increase the skin’s uptake of aromatic hydrocarbons and that the amount of PAH exposure will go up with the amount of bare skin exposed.
And while covering up with protective aprons, long sleeves and pants is recommended, they note that fabric will actually start passing PAHs to the skin “once the absorption capacity of clothes is partially breached” during a barbecue.
Furthermore, once fully saturated, clothing can become a potent reservoir of PAHs ready to be sucked up by the skin long after the charcoal flames have been extinguished.
Their advice? Wash your clothes right after you participate in any backyard grilling soirees.