In his State of the Union address this week, President Obama drew a line in the sand on toxics. "I will not back down from protecting our kids from mercury poisoning," he stated. A number of listeners might have missed the challenge, imbedded as it was within a myriad of other details in the hour-long speech. Others may have caught something about mercury, but been left puzzling over why this issue was an issue. The enigma is worth deciphering.

State of the Union

Mercury, a.k.a. quicksilver, is one of the oldest toxic materials known to humankind, recognized from antiquity as a slow-working and deadly poison, ever since mines of Spain were worked by the Romans. The naysayers and nabobs of the Neanderthal political right might grudgingly admit mercury isn't particularly good for you. They can even take inspiration from Charles Dickens. He penned the following proto-libertarian tirade in Bleak House: "As to corporations, parishes, vestry-boards, and similar gatherings of jolter-headed clods.....they ought to be worked in quicksilver mines for the short remainder of their miserable existence."

Mercury is an elemental metal that flows as a liquid at room temperature and easily vaporizes, facilitating its ability to wreak toxic havoc. Historically, one of the most widespread and hazardous applications of mercury was in felt-making for fur hats. This 17th century technological advancement made it possible to manufacture hats with passable attributes using low-quality rabbit fur. This proved a godsend for the beaver, whose pelt was a far more desirable starting material for felt, but