Super Eco

Photo credit: sarah gilbert, flickr

Mercury is an element with the symbol Hg, one of six elements that are liquid at or near room temperature. Mercury is used in thermometers, barometers, and other scientific apparatus, although modern concerns about toxicity have lead to its replacement by alcohol-filled and digital devices.

The toxicity of mercury depends on its solubility. In its insoluble form, or mercuric sulfide, mercury is harmless; this is typically mined as cinnabar. It can be converted to liquid mercury, or quicksilver, by crushing the ore and roasting it in rotary furnaces. Though the ore is harmless, its extraction and manufacture into liquid mercury is extremely dangerous and often results in mercury poisoning. Mercuric chloride, methylmercury, or (at the most toxic end of the spectrum) dimethylmercury are toxic to humans and animals.

Methylmercury is a bioaccumulative environmental toxin; in other words, it persists in the environment for many years and accumulates in the bodies of humans and other organisms. It is biomagnified as it travels through the food chain; in other words, it appears in higher concentrations in each larger predator. For this reason, the flesh of very large fish and mammals such as whales that eat other fish have much higher concentration of mercury than small fish which eat mostly plankton and other tiny organisms (herring, anchovies and sardines, for instance). Mercury also enters the environment through disposal of mercury-containing products such as batteries, thermometers, thermostats, medical products, flourescent bulbs, and auto parts. Also, up until 1985, plants which produced chlorine or caustic soda often used mercury as part of the manufacturing process, creating the majority of mercury pollution in the U.S. until the late 1900s. Mercury is infamous for its part in one of the greatest industrial disasters in history, in Minamata Bay, Japan. The Chisso Corporation, a fertilizer/petrochemical company, polluted the bay from 1932–1968, sickening or killing about 3,000 people, who suffered various deformities, severe mercury poisoning symptoms or death from what became known as Minamata disease.

Mercury is a "heavy metal" and, in water soluble forms, is extremely toxic. In children and adults, ingesting mercury is linked to autoimmune disease and increased risk of cardiovascular disease. Mercury crosses the placenta easily, and in utero exposure is linked to developmental deficits, especially attention disorders, sensory problems, and birth defects.

Mercury enters the environment through manufacturing processes that utilize mercury and through burning fossil fuels, especially coal. About 48 tons of elemental mercury is released into the atmosphere each year through smokestacks. Volcanoes, forest fires, and the weathering of mercury-bearing rocks also contributes inorganic mercury to the atmosphere (about 150 tons each year), and these amounts would not have a major effect on the environment were it not for anaerobic organisms which live in the soil and in water; their action on inorganic mercury produces methlymercury and results in mercury poisoning. Acute mercury poisoning can be characterized by neurological symptoms including loss of physical coordination, speech difficulties, hearing impairment, blindness, and death.