Health Impacts and Biomarkers of Prenatal Exposure to Methylmercury: Lessons from Minamata, Japan
National Institute for Minamata Disease, Minamata, Kumamoto 867-0008, Japan
Development and Environmental Medicine, Tohoku University Graduate School of Medicine, Miyagi 980-8575, Japan
Faculty of Chemistry, Thai Nguyen University of Sciences, Thai Nguyen 250000, Vietnam
Institute of Chemistry, Vietnam Academy of Science and Technology, Hanoi 100000, Vietnam
Department of Environmental Health Sciences, Akita University School of Medicine, Akita 010-8543, Japan
Author to whom correspondence should be addressed.
Toxics 2018, 6(3), 45; https://doi.org/10.3390/toxics6030045
Received: 13 June 2018 / Revised: 26 July 2018 / Accepted: 31 July 2018 / Published: 3 August 2018
(This article belongs to the Special Issue Mercury and Methylmercury Toxicology and Risk Assessment)
The main chemical forms of mercury are elemental mercury, inorganic divalent mercury, and methylmercury, which are metabolized in different ways and have differing toxic effects in humans. Among the various chemical forms of mercury, methylmercury is known to be particularly neurotoxic, and was identified as the cause of Minamata disease. It bioaccumulates in fish and shellfish via aquatic food webs, and fish and sea mammals at high trophic levels exhibit high mercury concentrations. Most human methylmercury exposure occurs through seafood consumption. Methylmercury easily penetrates the blood-brain barrier and so can affect the nervous system. Fetuses are known to be at particularly high risk of methylmercury exposure. In this review, we summarize the health effects and exposure assessment of methylmercury as follows: (1) methylmercury toxicity, (2) history and background of Minamata disease, (3) methylmercury pollution in the Minamata area according to analyses of preserved umbilical cords, (4) changes in the sex ratio in Minamata area, (5) neuropathology in fetuses, (6) kinetics of methylmercury in fetuses, (7) exposure assessment in fetuses.