Mercury is often mentioned as a toxic element that humans have been getting increased exposure to in recent decades.  Although mercury is a naturally occurring element that is released into our environment from volcanic eruptions, about two-thirds of the mercury we are exposed to is entering our biosphere from man-made sources including industrial plants, coal burning and incinerators.  Coal fired power plants release about 75 tons of mercury into the atmosphere each year. Historically, the chlor-alkali industry is one of the largest industries that used mercury in the processing of sodium chloride brine to chlorine gas, hydrogen gas and sodium hydroxide.  Most would be surprised to know how pervasive these chemicals are and how they are used in the food industry, aluminum and textile production, soap and other cleaning agents as well as water treatment and effluent control.