Association between concentrations of chromium in drinking water and mortality due to suicide in Alabama

Preclinical studies and clinical data from case series and placebo-controlled trials suggest that chromium might have antidepressant effects. We conducted an observational study in order to assess the association between concentrations of chromium in drinking water and mortality due to suicide in Alabama. Publicly available databases were used to determine both county-level concentrations of chromium in drinking water and county-level rates of mortality due to suicide in the years 2005–2015. Data analyses comparing county-level concentrations of total chromium in drinking water with mortality rate due to suicide were conducted using a two-tailed nonparametric Spearman's rank correlation, with statistical significance set at p ≤ 0.01 and 99% confidence interval. Sub-analyses were conducted examining males, females, whites, and blacks/other minorities. There were no statistically significant findings concerning concentrations of chromium and suicide rate in the general population (p = 0.35, r = −0.12); however, there was a statistically significant inverse relationship between the concentration of chromium and suicide deaths in whites (p = 0.009, r = −0.32). There were no statistically significant findings in the remaining demographic subgroups. Chromium in drinking water might have a protective effect against mortality due to suicide, at least in the Caucasian population.