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Description
Tobacco is a major public health threat around the world. Toxic tobacco chemicals are distributed via mainstream, secondhand, and thirdhand smoke (THS). THS refers aged tobacco smoke residue, a mixture of gases and particles that deposit and adsorb onto surfaces and dust. This study analyzed Minnesota house dust samples for nicotine and tobacco specific nitrosamine (TSNA) concentrations and evaluated cancer risks associated with the TSNA carcinogens. Twenty-nine settled house dust samples were collected from known smoker's homes using a High Volume Small Surface Sampler (HVS3) vacuum. Twenty-two dust samples had detectable amounts of nicotine and at least 1 TSNA. Our study observed nicotine levels that were relatively lower than other THS studies. Nicotine levels were significantly larger than the most abundant TSNA (NNK) in both concentration (median 0.904ng/g vs. 0.741_g/g; p<0.005) and loading data (median 1.10ng/m2 vs. 0.961_g/m2; p<0.0005). Linear regression tests showed a positive association between nicotine and each individual TSNA (p<0.0005). The results suggest cigarette smoke is a source of TSNA and nicotine is a reliable predictor for TSNA in THS contaminated house dust. Cancer risks through non-dietary exposure to the observed TSNA concentrations did not exceed the upper-bound risk of one cancer case per one million people, set by the U.S. E.P.A. The highest risk was seen in non-dietary lifetime exposure to NNK (0.187 cancer cases per 1,000,000). However, the risk assessment did not include other exposure routes and other carcinogens present in tobacco smoke. Nicotine-to-TSNA ratios were lower in the Minnesota dust than in secondhand and mainstream smoke, suggesting TSNAs persist and become more potent over time. Results from this study provides strong evidence of the persistence of tobacco smoke in indoor environments and highlights the potential short-term and long-term health consequences of THS contaminated house dust.
