Methylmercury exposure and health effects in humans

Abstract

Environmental context. Dietary intake of fish and other seafood products is the dominant source of human exposure to methylmercury, a toxicant that can have serious adverse effects on the developing nervous system and may promote heart diseases. The existing evidence of human toxicity should inspire prudent choices in maintaining fish intakes to secure an ample supply of essential nutrients, while at the same time choosing species that are low in mercury concentrations. The combination of essential nutrients and avoidance of this toxic contaminant will benefit brain development and human health in general. In addition, current contamination levels suggest that intensified efforts are needed to reduce and eliminate mercury release to the environment.Abstract. Methylmercury (MeHg) is a worldwide contaminant found in seafood and freshwater fish, which constitute the dominant source of human exposure to this substance. The developing human brain is particularly susceptible to injury caused by MeHg, which easily passes the placental barrier. Epidemiological studies in fishing populations have found subtle though lasting adverse effects on brain functions of children who were exposed prenatally to MeHg from seafood diets. This contaminant also seems capable of promoting the development of heart disease. Fish and seafood also contain important nutrients, such as omega-3 fatty acids that may provide beneficial effects, thereby possibly counteracting or obscuring the adverse effects of MeHg. This article reviews the existing evidence on MeHg developmental neurotoxicity and the emerging evidence that MeHg may promote the development of heart diseases. MeHg risks may have been underestimated in the past, in part because of the confounding effects of nutrients from seafood and fish. Improved control of mercury release to the environment is indicated. In addition, regulatory agencies should provide better guidance to consumers in maintaining a balanced diet that includes seafood as low as possible in mercury.

Environmental health indicators: a review of initiatives worldwide

“…In recent years, methods for biomonitoring have advanced considerably, allowing the measurement and interpretation of a range of different agents, in different human body tissues or fluids, and their interpretation as either markers of exposure or potential health effect (Becker et al, 2003, Smolders et al, 2009). For example, hair can be tested to determine past exposure to organic mercury -a biomarker of exposure (Choi and Grandjean, 2008), while saliva has been used to quantify cholinesterase activity, a biomarker for potential neurotoxic effects (Henn et al, 2006, Wang et al, 2008. Only one example of using biomonitoring as the basis for an indicator was found in the programmes reviewed here -the use of blood cotinine to indicate exposure to nicotine as a marker of children's second-hand smoke exposure.…”

Mercury Speciation at a Coastal Site in the Northern Gulf of Mexico: Results from the Grand Bay Intensive Studies in Summer 2010 and Spring 2011

“…Mercury deposits to watersheds and receiving water bodies where it can be converted to methylmercury, a highly toxic form, and, thus, enters the food chain through bioaccumulation [7]. Methylmercury can adversely affect the nervous system, particularly those of fetuses and young children [8]. Human exposure to mercury is primarily from the consumption of contaminated fish and other aquatic organisms [5,8,9].…”

A gradient of mercury concentrations in Scottish single malt whiskies

“…It is a potent neurotoxicant (e.g. Davidson et al 2004;Mergler et al 2007) with the developing human brain particularly susceptible to injury (Choi and Grandjean 2008) and as a consequence women of childbearing age are considered an especially vulnerable population (WHO 2013). A Provisional Tolerable Weekly Intake (PTWI) value of 1.6 µg kg -1 body weight (bw) has been set for methylmercury and 4 µg kg -1 bw for inorganic mercury (WHO 2003(WHO , 2010.…”