Acute mercury poisoning
Mercury poisoning differs from the other forms of metal poisoning in that it causes neurological symptoms rather than digestive disorders. The source of mercury poisoning is primarily contamination of food by polluted water containing mercuric compounds from industrial waste or organic mercury contained in some fungicides. Food or feed grains treated with mercury-containing fungicides are a potential source for transmission of the metal through both animal and cereal foods. The onset time is one week or more, at which time the symptoms of numbness, weakness of the legs, spastic paralysis and impaired vision are noted. Blindness and coma are extreme symptoms of the poisoning.

Chronic mercury poisoning
The symptoms of low-level, chronic mercury exposure and toxicity can be very general and difficult to diagnose based on symptoms alone. In addition, individuals show varying levels of sensitivity to the presence of mercury: amalgam removal may be very important in the recovery process of one person, while for another it may be best to leave the amalgams in place.

Mercury is usually targeted because it is the most common toxicity that most people have - for example, amalgams in teeth contain over 50% mercury. The remainder is made up of silver and sometimes tin, aluminum and other metals. The mercury escapes the amalgam as a vapor and is breathed into the body of the person carrying the amalgam.

Elemental and inorganic mercury exposure can come from amalgam fillings, burning of coal and medical wastes, and environmental and occupational exposures. While these forms of mercury are toxic, they pale in comparison to the toxicity of methylmercury. Methylmercury is formed through microbial action from inorganic mercury that has deposited in the oceans and lakes and bioaccumulates through the food chain in ever increasing concentrations through the large predatory fish. Seafood contamination is a significant source of organic mercury and a serious concern worldwide.

Two scientists completed a study that involved taking measurements of mercury in cicadas, particularly in areas where there were power plants. Their goal was to use their method as a type of indicator that the soil they were in would become polluted. Researchers cautioned people against eating any kind of insect like cicadas, which surprisingly were the carriers of heavy metals. Further investigations have been initiated to determine whether the mercury concentration in the cicadas came from man-made factors or occurred from natural sources such as soil. [Science Daily June 1, 2004]

There is a web site that you can access calledGotMercury.org. They have a simple, yet handy, calculator that you can use to estimate your mercury risk based upon your weight and current fish consumption.