Dermal Uptake of Thirdhand Cigarette Smoke from Clothing

Smoking leads to the accumulation of smoke chemicals on indoor materials like furniture, bedding and clothing. Little is known about the uptake of nicotine and nitrosamines from clothing and other indoor materials.

We exposed cotton clothing to cigarette smoke under controlled conditions. Using a crossover study design, healthy nonsmokers who were not normally exposed to smoke wore the smoked clothing and clean clothing for three hours at separate study visits. We compared urinary concentrations of cotinine and 3-hydroxycotinine, which are metabolites of nicotine, and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) which is a metabolite of the tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK).

One three-hour dermal exposure to thirdhand smoke on clothing led to statistically significant increases in the concentrations of nicotine and NNK metabolites in the urine of all participants (p-values <0.001). Normalized to creatinine, the peak median cotinine concentration after THS exposure was 62 times that seen after the control exposure. Likewise, peak 3-hydroxycotinine was 51 times higher than control and NNAL 46 times higher.

This is the first demonstration of dermal uptake of NNK in a controlled human exposure study. The concentrations of nicotine and NNK metabolites were like those of people with chronic high exposure to secondhand smoke. Clearance of nicotine was slower than in inhalation exposure studies, suggesting a dermal reservoir for nicotine. Dermal uptake from clothing and other surfaces can be a significant source of exposure to nicotine, NNK and other toxicants in tobacco smoke.