New evidence demonstrates that even low levels of mercury exposure may be hazardous. The purpose of this document is to provide health professionals with updated information on mercury and guidance on preventing toxic exposures in health care workers and their clients. It is also present in some fossil fuels. Its health hazards have been known at least since the roman conquest of Spain. Due to the toxicity of mercury in cinnabar, criminals sentenced to work in quicksilver mines by the Romans had a life expectancy of only 3 years.
Mercury is present in numerous chemical forms.
Elemental mercury itself is toxic and cannot be broken down into less hazardous compounds. Not only are these methylated mercury compounds toxic, but highly bioaccumulative as well. The increase in mercury as it rises in the aquatic food chain results in relatively high levels of mercury in fish consumed by humans. Widespread poisoning of Japanese fisherman and their families occurred in Minamata, Japan in the 1950's as a result of consumption of methyl mercury contaminated fish. Today, we continue to be exposed to mercury in our diets, primarily from fish and shellfish.