About 10 million people in the United States suffer from severe multiple chemical sensitivity. Symptoms — which may last for hours or days — include severe headaches, pain in joints and muscles, fatigue, dizziness and impaired thinking. Sufferers can be affected by such environments as air travel, the work place, their own home, the detergent aisle in the grocery store or close-quarter social events.
The onset of this chronic condition can usually be traced to an exposure to certain chemicals. But why the initial exposure results in an often life-long, incurable condition has been a mystery. In an article published in the September 2002 issue of the prestigious publication of the Federation of American Societies of Experimental Biology, “The FASEB Journal,” Washington State University biochemist Martin Pall suggests that a vicious chemical cycle may be to blame.
Pall’s new theory is a fusion of two previous ones. The first, proposed earlier by Pall, states that MCS is produced by excessive levels of two chemicals in the body — nitric oxide and its oxidant product, peroxynitrite. He suggested certain mechanisms act to keep levels of the two compounds elevated, thus producing chronic changes. The second theory was proposed by Dr. Iris Bell of the University of Arizona. She proposed that the central mechanism in MCS is neural sensitization in the brain.
“If you assume both previous theories are correct,” said Pall, “you come up with a fusion that explains all the most puzzling features of MCS. It explains why MCS is induced by a previous chemical exposure and why MCS sufferers show such a high level of sensitivity to a wide range of organic chemicals.”
Pall cites many studies that suggest that the initial chemical exposure creates hypersensitivity in the neurons in the brain, which react by creating the two chemicals that cause further hypersensitivity.
“Ordinarily, these activities are highly regulated, acting only on specific synapses in the brain where they are involved in learning and memory,” said Pall. “The MCS response is produced when chemical exposure produces excessive responses over large regions of the brain. In this way, normal and important mechanisms may act to generate this chronic illness. Thus, not only is the brain constantly inundated by chemicals to which it is normally somewhat sensitive, but the brain of a person suffering from MCS becomes abnormally sensitive to the chemicals,” he added.
MCS overlaps with other medical conditions of uncertain mechanism including chronic fatigue syndrome, fibromyalgia, posttraumatic stress disorder, and Gulf War syndrome. Pall has proposed similar mechanisms for all of these conditions.
“The notion that a biochemical vicious cycle may underlie all four is very exciting and, if correct, suggests that this is a major new paradigm of human disease,” said Pall, adding that interrupting this cycle may be the key to effective MCS treatment.
