Analysis of the association between blood heavy metals and tinnitus

Tinnitus is a common symptom among adults in the United States. Increasing evidence indicates that prolonged exposure to heavy metals and excessive intake of trace elements from environmental pollution can increase the likelihood of hearing loss. Although studies have reported associations between heavy metals and hearing loss, the relationship between heavy metals and tinnitus remains uninvestigated. After accounting for the complex survey design, we assessed cross-sectional data on blood lead, cadmium, mercury, selenium, and manganese levels in 4950 participants from the National Health and Nutrition Examination Survey database (2012-2018). We used weighted multivariate logistic regression, weighted multivariate linear regression, restricted cubic spline regression, and receiver operating characteristic curve analysis to investigate the relationship between these 5 blood heavy metals and tinnitus. Subgroup and sensitivity analyses were performed to evaluate consistency across subgroups and the robustness of the findings. Compared with the lowest quartile (Q1), the odds of tinnitus were significantly higher in the highest quartiles of blood lead (odds ratio = 1.63, 95% CI: 1.23-2.16) and cadmium (odds ratio = 1.32, 95% CI: 1.02-1.70). Restricted cubic spline curves indicated a nonlinear association between the odds of tinnitus and blood lead, cadmium, mercury, and selenium levels. However, no nonlinear relationship was found regarding blood manganese levels (P for nonlinear = .1334; P total = .2446). Subgroup analyses suggested that sex and ethnicity may modify the strength of the association between blood cadmium and blood lead levels with tinnitus prevalence. The association between blood mercury levels and tinnitus was highly homogeneous and stable across all examined demographic and clinical subgroups. The link between blood selenium levels and tinnitus was more pronounced among males, non-Hispanic whites, and individuals aged 40 to 60 years. Blood lead, cadmium, mercury, and selenium levels were significantly associated with the prevalence of tinnitus. High levels of these metals may be potential indicators for tinnitus management.