James Young Simpson (1811–1870)
HAMMERING THE HOOKWORM. It may be difficult for the contemporary reader to believe that carbon tetrachloride, now vilified as an environmental hazard, was used internally for the treatment of hookworm infections. The hookworm is an intestinal parasite, located primarily in tropical and subtropical climates worldwide, that infects some 600 million to 1.3 billion people. Walking barefoot on hookworm egg–contaminated soil can prompt an infection. The eggs penetrate the skin, travel to the intestine, and cause anemia.
Several years after James Simpson introduced chloroform for use as a surgical anesthetic in 1847, he studied the anesthetic effects of carbon tetrachloride, a chemical very similar to chloroform (CCl4 versus CHCl3). Although extremely powerful as an anesthetic, because of its toxicity it proved unsatisfactory and was set aside as a drug for the next seven decades.
In 1921, Maurice Hall, Zoology Chief at the U.S. Department of Agriculture, reported that carbon tetrachloride was 100 percent effective in eradicating hookworms from dogs. He proposed that it be used in humans, and it lived up to clinical expectations. Within a score of years, however, the effective-but-less-toxic tetrachloroethylene had replaced it.
Carbon tetrachloride had a far greater and more long-lasting impact in the industrial sector than as a drug. Nonflammable, noncorrosive, readily available, and very inexpensive, it was formerly used as a flame-extinguishing chemical in fire extinguishers, a dry-cleaning solvent, a spot-cleaning fluid, a starting material in the synthesis of chlorofluorocarbon (CFC) refrigerants, as well as a nail-polish remover.
The established toxic effects caused by inhaling carbon tetrachloride vapors in poorly ventilated settings led to its disuse in the 1990s. Early symptoms of high-level exposure included behavioral effects, loss of consciousness, and respiratory or heart failure. More common, however, were the damaging effects on the liver and kidneys after repeated exposure to the chemical.
SEE ALSO Chloroform (1847), Praziquantel (1972).
Hookworm infections have no symptoms. The most serious consequences of the infection are anemia and protein deficiency at the site where the worm attaches to the inner wall of the intestines. In children, the loss of iron and proteins can slow growth and can cause mental retardation.