Human exposure to mercury and its hematological effects: a systematic review

Abstract

Mercury is a metal found in the environment from natural and anthropogenic sources. It is highly toxic to ecosystems and living beings. Most human exposures come from ingestion of contaminated seafood, outgassing from dental amalgam or occupational exposure (e.g. gold mining), among other cases. Large populations are exposed to mercury, making it a very important issue from the public health perspective. Adverse health effects are commonly seen in the nervous system, but every organ is a potential target, such as the bone marrow. The main goal of this study was to assess the available evidence on human exposure to mercury and its hematological effects. A search strategy was constructed, including key terms (MeSH, text word and equivalents) for querying 2 repositories of master dissertation and PhD thesis (Fiocruz/ARCA and University of São Paulo) and 4 different electronic databases: BVS/ LILACS, MEDLINE/PubMed, Scopus and TOXLINE/NIH, for articles published from 1950 to February 2018. There was no language restriction and a tool (EPHPP) was used to assess the quality of included studies. According to pre-established criteria, 80 studies were retrieved, all of them observational (48 case reports, 24 cross-sectional, 6 case series and 2 cohorts), comprising 9,284 people. Despite the fact that most exposed ones (6,012) had normal blood cell count and mercury hematological effects did not seem very usual (1,914 cases: 14 severe and 29 deaths), three studies reported association (β) for anemia, lymphopenia, neutrophilia and basophilia. We concluded that the gathered information pointed to mercury hematotoxic effects, some of them may be serious and even fatal.

Genetic Polymorphism of Delta Aminolevulinic Acid Dehydratase (ALAD) Gene and Symptoms of Chronic Mercury Exposure in Munduruku Indigenous Children within the Brazilian Amazon

“…Genetic analysis identified two children with the ALAD polymorphism who had high levels of mercury in their hair samples and severe symptoms of chronic mercury exposure. Although there is a growing number of studies investigating the effects of chronic exposure to mercury on population health [5,8,25,26], little is known about the influence of the individual's genetic susceptibility on mercury toxicokinetics and toxidinamics, thus gaps remain in our knowledge about the role that genetic variability plays.…”

“…Almost half of the studied population had anemia (Hb level ≤ 11.5 g/dL). There is little evidence in the literature regarding this matter [26], however, a few recent studies showed an inverse association between hemoglobin levels and mercury exposure in the last decade [52][53][54]. A study from 2017, conducted with 83 children from the Peruvian Amazon region, demonstrated that MeHg exposure was associated with toxicant-induced anemia [54].…”

Erythrocytes as a Model for Heavy Metal-Related Vascular Dysfunction: The Protective Effect of Dietary Components

“…In a recent review, Vianna et al [ 111 ] discuss the available evidence on potential hematological effects of human mercury exposure, including lymphopenia, lymphocytosis, neutrophilia and basophilia. The possible occurrence of anemia associated with Hg exposure has also been reported [ 111 , 112 ], likely due to hemolysis [ 112 , 113 , 114 ], loss of blood from the direct effect on the gastrointestinal mucosa and apoptosis [ 112 , 114 ]. Similarly to apoptosis of nucleated cells, RBC may undergo programmed cell death, also called eryptosis [ 115 , 116 ].…”

Cellular and Molecular Mechanisms of Environmental Pollutants on Hematopoiesis

“…Exposure to HMs can cause disturbances in the hematological system and can be used as biological end-points for assessing HM exposure; HM intoxications cause immunosuppression, anemias, and leukemias and disrupt coagulation [ 223 , 224 , 225 , 226 ]. While HM exposure can directly impact circulating blood cells, several toxic effects occur in the BM environment and affect hematopoiesis.…”

“…Hg is toxic to virtually every human organ; due to its affinity for sulfhydryl groups, Hg alters tertiary and quaternary structures of proteins and disrupts membrane permeability [ 259 ]. Disturbance of hematopoietic systems is also a hallmark of Hg intoxication, characterized mainly by anemia and lymphocytopenia [ 223 , 260 ].…”