Transportation Noise and Risk of Tinnitus: A Nationwide Cohort Study from Denmark

Abstract

Background: There is a growing body of evidence linking residential exposure to transportation noise with several nonauditory health outcomes. However, auditory outcomes, such as tinnitus, are virtually unexplored.

Objectives: We aimed to investigate the association between residential transportation noise and risk of incident tinnitus.

Methods: We conducted a nationwide cohort study including all residents in Denmark age $\ge 30y$, of whom 40,692 were diagnosed with tinnitus. We modeled road traffic and railway noise at the most ($L_{\text{den}}\text{max}$) and least ($L_{\text{den}}\text{min}$) exposed façades of all Danish addresses from 1990 until 2017. For all participants, we calculated 1-, 5-, and 10-y time-weighted mean noise exposure and retrieved detailed information on individual- and area-level socioeconomic covariates. We conducted analyses using Cox proportional hazards models.

Results: We found positive associations between exposure to road traffic noise and risk of tinnitus, with hazard ratios of 1.06 [95% confidence interval (CI): 1.04, 1.08] and 1.02 (95% CI: 1.01, 1.03) per 10-dB increase in 10-y $L_{\text{den}}\text{min}$ and $L_{\text{den}}\text{max}$, respectively. Highest risk estimates were found for women, people without a hearing loss, people with high education and income, and people who had never been in a blue-collar job. The association with road $L_{\text{den}}\text{min}$ followed a positive, monotonic exposure-response relationship. We found no association between railway noise and tinnitus.

Discussion: To our knowledge, this is the first study to show that residential exposure to road traffic noise may increase risk of tinnitus, suggesting noise may negatively affect the auditory system. If confirmed, this finding adds to the growing evidence of road traffic noise as a harmful pollutant with a substantial health burden. https://doi.org/10.1289/EHP11248.

Figure 1.

Associations between 10-y mean exposure to road traffic noise at the most (A) and least (B) exposed façades and risk of tinnitus using the fully adjusted model. The vertical bars show hazard ratios with 95% confidence interval at the median of the exposure categories compared with the reference category. Reference category was $<45\text{\hspace{0.17em}dB}$ for ${\mathrm{L}}_{\text{den}}\text{max}$ and $<40\text{\hspace{0.17em}dB}$ for ${\mathrm{L}}_{\text{den}}\text{min}$. Risk estimates and number of cases for each exposure category are shown in Table S3.

Figure 2.

Effect modification analysis of associations between 10-y mean road traffic noise (continuous, per 10 dB, using the fully adjusted model) at the most and least exposed façade and risk of tinnitus by: hearing loss diagnosis, sex, education, income, green space ($150\mathrm{m}$), occupation, and comorbidity. Risk estimates and number of cases in each modifier subgroup are shown in Table S5.