Relationships of local lithium concentrations in drinking water to regional suicide rates in Italy

<p><i>Objectives</i>. Higher natural concentrations of lithium in drinking water may be associated with lower local rates of suicide. <i>Methods</i>. Lithium concentrations in drinking water were assayed by mass spectrometry at 145 sites in Italy, and compared with reported local suicide rates for men and women between 1980 and 2011. <i>Results</i>. Lithium concentrations in drinking water averaged 5.28 [CI: 4.08–6.48] μg/L (0.761 [0.588–0.934] μEq/L) and ranged from 0.110 to 60.8 μg/L (1.58 to 8.76 μEq/L). Lithium concentrations and local suicide rates were not significantly inversely related, except in 1980–1989, particularly among women. <i>Conclusions</i>. A proposed association between trace lithium concentrations in drinking water and risk of suicide was only partially supported, and mechanisms for potential clinical effects of trace levels of lithium are unknown.</p>