Systematic Review of Mercury Exposures Worldwide: Findings from the 2018 WHO/UN Global Mercury Assessment

Abstract

The Minamata Convention on Mercury Pollution provides a mandate to take action against global mercury pollution. However, our knowledge of mercury exposures around the world remains limited. As part of the 2018 UN Global Mercury Assessment, WHO led the current study to increase worldwide understanding of human exposures to mercury by collating and analysing mercury concentrations in biomarker samples via a systemic review. A systematic search of the peer-reviewed literature was performed with several a priori search strategies set. The overall work captured 424,884 mercury biomarker measures taken from 336,015 individuals represented in 312 articles from 67 countries. We identified four populations of concern for which there exist a relatively robust dataset: 1) Arctic populations (mainly Inuit) who consume fish and marine mammals; 2) tropical riverine communities (especially Amazonian) who consume fish, and in some cases may be exposed to mining operations; 3) coastal and/or small-island communities who are avid seafood consumers; and 4) individuals who either work or reside amongst artisanal and small-scale gold mining (ASGM) sites. Individuals in select background populations worldwide with insignificant exposures to mercury sources have blood mercury levels that generally fall under 5 mg/L and urine mercury levels that fall under 3 mg/L. This systematic review documents that all people are exposed to some amount of mercury, and that there is great variability in exposures around the world. This type of information is critical in helping understand exposures particularly in light of the Minamata Convention on Mercury Pollution and certain stipulations within the Convention text (e.g., can inform Article 22’s effectiveness evaluation especially for vulnerable populations; gauge changes over geographic space and time).