Rethinking treatment of mercury poisoning: the roles of selenium, acetylcysteine, and thiol chelators in the treatment of mercury poisoning: a narrative review

Abstract

We reevaluate the treatment of mercury poisoning, incorporating recent advances in understanding of mercury toxicity and the mercury:selenium interaction. This review focuses on: 1) the role, limitations and benefits of chelation (Unithiol, succimer and N-Acetylcysteine); 2) the role of selenium supplementation; and 3) how the different forms of mercury are impacted by use of chelation and selenium. Unithiol and succimer produce increases in urinary excretion of mercury and to a lesser degree blood and total body mercury. The primary role of N-acetylcysteine is increasing renal mercury excretion, similar to the thiol-chelators. Additional unique features of acetylcysteine include increased efflux of methylmercury from the brain, and reduced oxidative stress via increased glutathione production. The role of selenium includes: 1) restoration of selenoprotein activity, 2) protection against mitochondrial injury and DNA damage, 3) demethylation of methylmercury, 4) sequestering of mercury via Hg:Se complexes, and 5) redistribution of Hg inside organisms. Selenium may increase blood Hg, via a "sink" effect, causing a redistribution of mercury away from the brain. A combined approach for mercury poisoning treatment was developed focusing on restoration of selenoprotein function, reduction of oxidative stress and increased mercury elimination.

Environmental and genetic predictors of whole blood mercury and selenium concentrations in pregnant women in a UK birth cohort

“…Hg has a strong affinity to Se-containing molecules such as selenoproteins in the thioredoxin, and glutathione peroxidase antioxidant systems ( Spiller, 2018 ). Se is involved in the demethylation of MeHg, binds with Hg, and facilitates transport and excretion ( Timmerman and Omaye, 2021 , Spiller et al., 2021 ). We expected that part of the predictive power of each element could reflect shared dietary sources, such as fish which contains both Hg and Se.…”

Perspective Chapter: The Toxic Silver (Hg)

“…Selenium and fish containing omega-3 fatty acids are thought to diminish mercury toxicity [33] via "restoring seleno protein activity" protection against mitochondrial injury and DNA damage, demethylation of methyl mercury and sequestration in complexes, as well as redistribution in the blood away from brain [43].…”

The Aging Kidney—As Influenced by Heavy Metal Exposure and Selenium Supplementation

“…Since the normal blood SH-concentrations of albumin-SH and GSH (totally above1000 µmol/L) are significantly greater than that of selenium, it appears reasonable that the major fraction of circulating mercury is bound to albumin and/or GSH rather than to Se-proteins, although a minor fraction of circulating mercury is coordinated to selenium compounds. A recent review of Spiller et al [85] remarks, besides the role of selenium supplementation, the pros and cons of chelation, and the impact of chelation and selenium on the different forms of mercury.…”