Tim Burton's new movie version of Alice in Wonderland is now playing - it stars Johnny Depp as the Mad Hatter. The Hatter's erratic, agitated behavior in the classic story refers to a real industrial hazard in Lewis Carroll's Britain of 1865. Hatters or hat-makers (adults) commonly exhibited slurred speech, tremors, irritability, shyness, depression, and other neurological symptoms; hence the expression "mad as a hatter." The symptoms were associated with chronic occupational exposure to mercury. Hatters toiled in poorly ventilated rooms, using hot solutions of mercuric nitrate to shape wool felt hats.
In a Dec. 24, 2009, interview with the Los Angeles Times, Johnny Depp was quoted as saying that he was aware of the implications of the Hatter's behavior: "I think [the Mad Hatter] was poisoned - very, very poisoned. And I think it just took [e]ffect in all his nerves. It was coming out through his hair and through his fingernails, through his eyes." In the new movie, Depp's Hatter has flamboyantly red hair. This presumably reflects the character's chronic exposure to an orange-colored solution containing mercuric nitrate that was used in a process called "carroting."
"Society has made great progress in recognizing and controlling industrial hazards since Lewis Carroll's day. For example, nearly 70 years ago, on December 1, 1941, the U.S. Public Health Service ended mercury's use by hat manufacturers in 26 states through mutual agreements. The kinds of conditions that put hat-makers and other industrial workers at risk in 1865 are no longer tolerated," said John Howard, M.D., Director of the National Institute for Occupational Safety and Health (NIOSH).
"However," Dr. Howard emphasized, "the Hatter remains a cautionary figure, since exposures to mercury and other hazardous industrial substances can still occur in the workplace. Symptoms from chronic exposures to mercury, lead, and other neurotoxic substances, even at low levels, may be subtle in early stages. Sometimes, they may be mistaken for symptoms that can arise from other causes. Similar concerns exist about other adverse effects that are associated with exposures on the job. It is important to be vigilant about work-related illness, and to act decisively to protect workers' health."
That said, why would any sane medical professional doubt that putting thimerosal - a mercury-containing preservative used in various vaccines and other products since the 1930's - "might" actually cause autism and/or other negative health effects - especially in children?