Lithium in Public Drinking Water and Suicide Mortality in Portugal: Initial Approach

Authors

  • Pedro Oliveira Psychiatry Department. Centro Hospitalar e Universitário de Coimbra. Coimbra. Institute of Psychological Medicine. Faculty of Medicine. University of Coimbra. Coimbra. https://orcid.org/0000-0002-2292-1463
  • Joana Zagalo Family Health Unit “CelaSaúde”. Regional Health Administration of Central Portugal. Coimbra.
  • Nuno Madeira Psychiatry Department. Centro Hospitalar e Universitário de Coimbra. Coimbra. Institute of Psychological Medicine. Faculty of Medicine. University of Coimbra. Coimbra.
  • Orquídia Neves CERENA (Centro de Recursos Naturais e Ambiente) & DECivil (Department of Civil Engineering, Architecture and Georesources). Instituto Superior Técnico. Universidade de Lisboa. Lisboa. Portugal.

DOI:

https://doi.org/10.20344/amp.10744

Keywords:

Drinking Water, Lithium, Portugal, Suicide, Water Supply

Abstract

Introduction: Lithium can be found naturally in drinking water. There is some evidence that natural levels of lithium in drinking water may have a protective effect on suicide mortality. The aim of this study is to evaluate if higher natural concentrations of lithium in public drinking water are associated with lower local rates of suicide in Portugal.

Material and Methods: Suicide standardized mortality ratios at 54 Portuguese municipalities within the 6-year period from 2011 to 2016 was correlated with lithium concentrations in public drinking water and socioeconomic factors using Pearson’s correlation coefficients (r) with one-tailed tests. Multivariate regression models were adjusted for well-known socioeconomic factors known to influence suicide mortality in Portugal (population density, average income per capita, unemployment rates and proportion of Roman Catholics).

Results: The average lithium level, as evidenced by raw values for 54 municipalities, was 10.88 μg/L (standard deviation = 27.18). There was no statistically significant correlation between lithium levels and suicide standardized mortality ratio (r = 0.001, p-value = 0.996). There was a statistically significant higher suicide standardized mortality ratio for males (p-value = 0.000). When analyzed separately for both sexes, no statistically significant correlation between suicide standardized mortality ratio and lithium levels was found (male r = 0.024, p-value = 0.862; female r = 0.000, p-value = 0.999). No association between suicide standardized mortality ratio and socioeconomic factors was found: population density (r = -0.144, p-value = 0.300), average income per capita (r = -0.112, p-value = 0.418), unemployment rates (r = -0.001, p-value = 0.994), and proportion of Roman Catholics (r =- 0.150, p-value = 0.278).

Discussion: Unlike most international studies regarding natural lithium levels and suicide risk, no inverse relation was found in Portugal. Factors such as the country’s low suicide rate, confunding suicide risk variables, and unaccounted lithium intake might have influenced these findings.

Conclusions: No association between lithium in public drinking water and suicide rates was found in Portugal.

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Published

2019-02-01

How to Cite

1.
Oliveira P, Zagalo J, Madeira N, Neves O. Lithium in Public Drinking Water and Suicide Mortality in Portugal: Initial Approach. Acta Med Port [Internet]. 2019 Feb. 1 [cited 2023 Feb. 6];32(1):47-52. Available from: https://actamedicaportuguesa.com/revista/index.php/amp/article/view/10744

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Original