Users of Smokeless Tobacco Have Higher Levels of Nicotine and Toxicant Exposure Than Cigarette Smokers
- Exclusive smokeless tobacco users have higher observed levels of exposure to nicotine and carcinogenic tobacco-specific nitrosamines than exclusive cigarette smokers.
- High exposure to harmful constituents among smokeless tobacco users puts them at risk for adverse health effects, including cancer.
- Further study is needed on the toxic constituents of smokeless tobacco products as well as their health effects on the individuals who use them.
A study analyzing data from a large, nationally representative U.S. health survey population comparing biomarkers of tobacco exposure in smokeless tobacco users and cigarette smokers has found the exclusive smokeless tobacco users have higher observed levels of exposure to nicotine and a cancer-causing toxicant than the exclusive cigarette smokers. Although the causes of the differences in exposure between the two groups is not understood, possible explanations include differences in the use of these products, such as how nicotine and other constituents are absorbed by the users, as well as differences in constituent levels in cigarette and smokeless tobacco due to tobacco type and curing and fermentation processes, according to the study by Rostron et al. The study was published in Cancer Epidemiology, Biomarkers & Prevention.
The researchers analyzed data on biomarkers of exposure to seven tobacco constituents available from 23,684 adult participants in the National Health and Nutrition and Examination Survey (NHANES) from 1999 to 2012. The seven biomarkers were selected for analysis based on their relevance to tobacco exposure and health outcomes. They included cotinine; NNAL; cadmium; lead; mercury; arsenic; and N-acetyl-S-(2-cyanoethyl)-L-cysteine (CYMA), a biomarker of exposure to tobacco smoke.
The investigators estimated geometric mean biomarker concentrations for smokeless tobacco users (488), cigarette smokers (6,791), dual cigarette and smokeless tobacco users (92), and nontobacco users (16,313). They also calculated geometric mean ratios using regression analysis to study the association between biomarker concentrations and tobacco use status.
The researchers found that the exclusive smokeless tobacco users had higher geometric mean concentrations of serum cotinine (178.9 ng/mL, 95% confidence interval [CI] = 145.5–220.0) and NNAL (583.0 pg/mg creatinine, 95% CI = 445.2–763.5) than exclusive cigarette smokers (130.6 ng/mL, 95% CI = 122.3–139.6 and 217.6 pg/mg creatinine, 95% CI = 193.0–245.2, respectively). Smokeless tobacco users also had higher concentrations of blood lead compared with nontobacco users (adjusted geometric mean ratio = 1.30, 95% CI = 1.21–1.38). Based on limited sample sizes, NNAL concentrations for smokeless tobacco users appear to have declined from 2007 to 2008 (geometric mean = 1013.7 pg/mg creatinine, 95% CI = 738.9–1390.8) to 2011 to 2012 (geometric mean = 325.7 pg/mg creatinine, 95% CI, 159.6–664.9).
Smokeless Tobacco Puts Users at Risk for Cancer
“Our analysis of data from NHANES, a large, nationally representative study of U.S. health behaviors and outcomes, generated results consistent with those from previous smaller studies,” said Brian L. Rostron, PhD, an epidemiologist in the Center for Tobacco Products at the U.S. Food and Drug Administration and the lead author of this study, in a statement. “Levels of biomarkers of exposure to nicotine and the cancer-causing tobacco constituent NNK were higher among exclusive smokeless tobacco users than exclusive cigarette smokers. This continues to put tobacco users at risk for adverse health effects, including cancer.
“Our findings demonstrate the need for continuing study of the toxic constituents of smokeless tobacco as well as their health effects on the individuals who use them. This is why the FDA and CDC are continuing to analyze and monitor biomarker levels among tobacco users and why the FDA and NIH are collaborating on the Population Assessment of Tobacco and Health (PATH) Study, a large longitudinal study in which biospecimens, such as blood and urine, have been collected.”
This study was funded by the U.S. Food and Drug Administration and the Centers for Disease Control and Prevention.
The study authors declared no potential conflicts of interest.