Exposure to a Tobacco-Specific Carcinogen Among Adolescent Smokeless Tobacco Users in Rural California, United States

Abstract

Introduction: Approximately the same percentage of male high school students in the United States currently uses conventional smokeless tobacco as smokes cigarettes, resulting in toxin exposure.

Methods: This study assessed tobacco product use (smokeless, combustible, and electronic cigarettes) and nicotine and carcinogen exposures in a sample of 594 male rural high school baseball players-a population traditionally at risk for smokeless tobacco use. Salivary specimens were assayed for cotinine (a biomarker of nicotine exposure) and urine specimens for 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL, a biomarker of the carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) using liquid chromatography-tandem mass spectrometry.

Results: The prevalence of past 30-day use of any tobacco product was 29%. Past 7-day smokeless tobacco use (prevalence: 13%) was associated with the highest levels of cotinine and NNAL observed in the sample, whether smokeless tobacco was used exclusively (geometric means: cotinine 11.1 ng/mL; NNAL 31.9 pg/mg-creatinine) or in combination with combustible products (geometric means: cotinine 31.6 ng/mL; NNAL 50.0 pg/mg creatinine). Cotinine and NNAL levels were incrementally higher in each increasing category of smokeless tobacco use frequency. However, observed levels were lower than previously reported for adults, likely reflecting less smokeless use per day among adolescents.

Conclusions: Based on these biomarker observations, adolescents who use conventional smokeless tobacco products are exposed to substantial levels of nicotine and NNK. Although exposed to lower levels than adult smokeless users, the findings are concerning given the young age of the sample and tendency for smokeless tobacco users to increase use intensity over time.

Implications: This study demonstrates that adolescents using smokeless tobacco are exposed to levels of nicotine and NNK that increase with use frequency and that exceed exposures among peers using other tobacco products. Youth smokeless tobacco use in the United States has not declined along with youth smoking prevalence, giving greater importance to this health concern. To reduce youth (and adult) exposures, needed actions include effective smokeless tobacco use prevention, potentially in combination with reducing the levels of harmful and potentially harmful chemicals in smokeless tobacco products currently popular among adolescents.

Figure 1.

Nitrosamine (4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol [NNAL]) exposure by smokeless tobacco use frequency. Box plots of urinary NNAL according to self-reported use frequency of smokeless tobacco (moist snuff, chewing tobacco, and/or snus). Box widths represent interquartile range on the logarithmic scale. Only plotted are values for individuals with measured NNAL levels above the lower limit of quantification (0.25 pg/mL urine), which excludes, by category: no use in the past 30 days (n = 257), no use in the past 7 days (n = 6), and used 1–6 days of the past 7 days (n = 1). Mean and median NNAL values that include these individuals (with assigned NNAL values of 0) are given in Table 3.