Mercury

History

There is evidence to suggest that mercury was known to the ancient Chinese and Hindus and was found in Egyptian tombs dating back to about 1500 BCE. Mercury has found many uses in ancient civilizations, including making of ointments, cosmetics, amalgams with other metals, and in alchemy. It was thought to prolong life, heal fractures, and preserve health. Indeed, it was named after the Roman god Mercury, known for his speed and mobility. It has been used as a diuretic, disinfectant, laxative, as a treatment for syphilis and worm infestation, in thermometers, in sphygmomanometers (blood pressure measuring devices), and as an antidepressant.

In the 18th and 19th centuries, mercury was used in the industrial process of carrotting, a method of treating fur in the process of making felt. Animal skins were rinsed in a solution of mercuric nitrate that helped open the sheaths surrounding each fur fiber and permitted matting (felting) of fibers in subsequent operations for making felt hats. The process, however, produced highly toxic mercury vapors and led to mercury poisoning among hatters. Many experienced tremors, emotional lability, insomnia, dementia, and hallucinations, and these symptoms led to the phase commonly used in medical parlance, “mad as a hatter,” which refers to someone poisoned by mercury. It was also known as Danbury shakes, due to the effects seen in Danbury, Connecticut, a center of hat making. The U.S. Public Health Service banned the use of mercury in the felt industry in December 1941.

Some prominent historical personalities known or believed to be affected by mercury toxicity include Sir Isaac Newton, King Charles II, and Sir Michael Faraday. Their erratic behavior was thought to correspond to their work with mercury. Abraham Lincoln also exhibited erratic behavior that was thought to be due to the mercury in the “blue pill” he took for depression.

Toxicology and Clinical Manifestations

Metallic or elemental mercury volatilizes to odorless mercury vapor at ambient air temperatures, and it can be absorbed via inhalation, with concerns particularly in poorly ventilated spaces. Inhalation of mercury vapors may produce inflammation of the respiratory passages and a pneumonitis-like syndrome and the triad of excitability, tremors, and gingivitis (the mad hatter syndrome). Inorganic mercury salts can be divalent (mercuric salts) or monovalent (mercurous salts). They are generally white powder or crystals, with the exception of cinnabar (mercuric sulfide), which is red. The greatest concentrations of mercury after exposure to the inorganic salts or vapors can be found in the kidney. Mercuric salts are more corrosive and toxic than the mercurous salts. “Pink disease” has been seen in children when teething powders containing mercurous mercury has been used and is characterized by fever; pink rash; swelling of the spleen, lymph nodes, and fingers; constipation or diarrhea; hair loss and irritability. Organic mercury compounds are formed when mercury combines with carbon. As noted above, methylmercury is the most important organic form of mercuryintermsofhumanhealtheffects.

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