Lincoln during in this 1858 Lincoln-Douglas debate is a far cry from our vision of Lincoln at the Lincoln Memorial, sitting patient and thoughtful with the weight of the nation on his shoulders. A study published in the Summer 2001, issue of Perspectives in Biology and Medicine reformulates a common anti-depressive medication of the nineteenth century and shows that it would have delivered a daily dose of mercury exceeding the current Environmental Protection Agency safety standard by nearly 9000 times.
"We wondered how a man could be described as having the patience of a saint in his fifties when only a few years earlier he was subject to outbursts of rage and bizarre behaviour," said Norbert Hirschhorn, M.D., retired public health physician, medical historian and lead author of the study.
"Mercury poisoning certainly could explain Lincoln's known neurological symptoms: insomnia, tremor and the rage attacks," said Robert G. Feldman, M.D., professor of neurology, pharmacology, and environmental health at the Boston University Schools of Medicine and Public Health, an expert on heavy metal poisoning and co-author of the paper. "But what is even more important, because the behavioural effects of mercury poisoning may be reversible, it also explains the composure for which he was famous during his tenure as president."
Lincoln was known to have taken "blue mass," a pill containing mercury, apparently to treat his persistent "melancholia," (then known also as hypochondriasis.) In 1861, a few months after the inauguration, however, perceptively noting that blue mass made him "cross," Lincoln stopped taking the medication.
"We wanted to determine how toxic the mercury in the blue mass pills was likely to be," said Ian A Greaves, M.D., associate professor of environment and occupational health and associate dean at the University of Minnesota School of Public Health, co-author. "We used a nineteenth century recipe to recreate blue mass. The ingredients included, besides mercury, liquorice root, rose-water, honey and sugar and dead rose petals. It was compounded with an old-fashioned mortar and pestle and rolled to size on a 19th century pill tile. But, in accord with 20th century safety standards, we wore surgical gowns, gloves, masks and caps and worked with modern ventilation equipment."
Caution was well advised. The method of compounding the blue mass pill, dispersing the mercury into fine particles and increasing its surface area, was meant to assure its absorption into the body and did. The vapour released by the two pills in the stomach would have been 40 times the safe limit set by the U.S. National Institute for Occupational Health. The solid element of mercury absorbed from two pills would have been 750micrograms. The EPA indicates that only up to 21micrograms of any form of mercury per day may safely be ingested. Someone who ate the common dose of two to three little pills per day would have seriously risked poisoning.
"The wartime Lincoln is remembered for his self-control in the face of provocation, his composure in the face of adversity," said Hirschhorn. "If Lincoln hadn't recognized that the little blue pill he took made him 'cross,' and stopped the medication, his steady hand at the helm through the Civil War might have been considerably less steady."
Sarah Youngerman, University of Minnesota, firstname.lastname@example.org, 612-624-4604
Gina Digravio, Boston University School of Medicine, email@example.com, 617-638-8491