This systematic review summarizes the finding of 58 studies from 33 countries, which assessed mercury concentrations in breast milk and the factors related to the level of contamination. We performed a literature search in Pubmed, Science Direct, and Google Scholar databases for studies published between 1976 and 2017 that are monitoring and measuring mercury in human breast milk and investigating the associated factors. Then, we extracted more information about the aim of the study, the country, samples size, time of lactation, mercury concentration, and other data. Most of the studies used mature milk or colostrum for analysis and in about 60% of them, the concentrations exceed significantly the limit set by the World Health Organization (WHO) of 1.7 µg/l; In addition, many factors and parameters were related to the level of mercury contamination in breast milk. Periodic monitoring surveys are recommended in each country to evaluate the level of mercury in milk of lactating women and to estimate the level of exposure of newborns.
Keywords: Mercury; breast milk; factors; levels.