Associations between blood cadmium and lead and postural balance in the National Health and Nutrition Examination Survey (NHANES), 2021–2023

Background Exposure to the heavy metal lead (Pb) is linked with postural balance in workers with elevated exposure, but risks from heavy metals at levels observed in the general population are uncertain. Objective Using a refined balance examination with enhanced sensitivity for a broad age range of participants available in the 2021–2023 National Health and Nutrition Examination Survey (NHANES), we assessed associations between blood Pb and Cd and vestibular dysfunction. Methods There were 3153 participants ages 20–69 with data on blood metals and vestibular dysfunction employing the improved Modified Romberg Test for postural balance. Associations were tested using log-binomial regression for pass/fail balance tests and hazard regression for time-to-failure analysis. Results After adjusting for age, race, sex, education, and smoking history, the highest quartile of cadmium (≥0.445 μg/L) was marginally associated with balance dysfunction compared to the lowest quartile (<0.158 μg/L): prevalence ratio (PR)= 1.16 (95% Cl: 0.97, 1.38) for failing one of the first 4 balance tests, and PR= 1.06 (95% Cl: 0.99, 1.14) for failing one of the 5 balance tests. No associations were observed with blood Pb or in failure time models. After incorporating sample weights and a more complete set of covariates in logistic regression models, odds ratio (OR) = 1.77 (95% CI: 1.10, 2.84) for upper quartile Cd with failing one of the first 4 balance tests, and OR= 1.43 (95% CI: 0.96, 2.13) for failing one of the 5 balance tests. Conclusions Low levels of blood cadmium may be associated with vestibular dysfunction.