Mercury in Fish: History, sources, pathways, effects, and indicator usage

Abstract

Methyl mercury is highly toxic to humans, particularly to the developing nervous system. Virtually all mercury in muscle tissue of naturally-occurring edible fish is in the form of methyl mercury, and fish consumption is the most common route of human exposure to methyl mercury. The monitoring of mercury in fish thus provides reliable indication of potential exposure of humans to mercury, and regulatory guidelines based on threshold levels of effects due to such exposure provides the best mechanism for effective avoidance of mercury toxicosis in populations throughout the world. This chapter traces the development of the use of mercury in fish as an indicator of potential harm to human health from early recognition of the dangers associated with methyl mercury, to the first records of major toxicity events attributable to fish consumption, through the sources of environmental contamination by mercury today, both natural and anthropogenic, and an overview of the mercury species, environmental conditions and pathways leading to uptake and bioconcentration of mercury in fish.