Cigarette- and Snus-Modified Association Between Unprotected Exposure to Noise from Hunting Rifle Caliber Weapons and High Frequency Hearing Loss. A Cross-Sectional Study Among Swedish Hunters

AIM: To investigate in this cross-sectional study among Swedish hunters if tobacco use modifies the previously observed association, expressed as prevalence ratio (PR), between unprotected exposure to impulse noise from hunting rifle caliber (HRC) weapons and high-frequency hearing impairment (HFHI). SETTINGS AND DESIGN: A nationwide cross-sectional epidemiologic study was conducted among Swedish sport hunters in 2012. MATERIALS AND METHODS: The study was Internet-based and consisted of a questionnaire and an Internet-based audiometry test. RESULTS: In all, 202 hunters completed a questionnaire regarding the hearing test. Associations were modeled using Poisson regression. Current, daily use of tobacco was reported by 61 hunters (19 used cigarettes, 47 moist snuff, and 5 both). Tobacco users tended to be younger, fire more shots with HRC weapons, and report more hunting days. Their adjusted PR (1–6 unprotected HRC shots versus 0) was 3.2 (1.4–6.7), P = 0.01. Among the nonusers of tobacco, the corresponding PR was 1.3 (0.9–1.8), P = 0.18. P value for the interaction was 0.01. The importance of ear protection could not be quantified among hunters with HRC weapons because our data suggested that the HFHI outcome had led to changes in the use of such protection. Among hunters using weapons with less sound energy, however, no or sporadic use of hearing protection was linked to a 60% higher prevalence of HFHI, relative to habitual use. CONCLUSION: Tobacco use modifies the association between exposure to unprotected impulse noise from HRC weapons and the probability of having HFHI among susceptible hunters. The mechanisms remain to be clarified, but because the effect modification was apparent also among the users of smokeless tobacco, combustion products may not be critical for this effect.