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Chemical sensitivity study by Miller identifies risks (5/12/95)

Findings from the largest study yet on multiple chemical sensitivity (MCS) suggest that everyday exposures to chemicals commonly used in homes and office buildings may trigger the same illnesses that some agricultural and industrial workers develop when they are exposed to potent pesticides.

"The long-term effects of organophosphate pesticides and solvents on certain workers are well known. Finding similar patterns of illness in individuals with MCS furnishes new evidence that chemical sensitivity may indeed be a biological condition, not simply a psychological aversion to odors," said Dr. Claudia S. Miller, MD, assistant professor of occupational and environmental medicine, who is principal investigator for the study. Results were published in the March/April issue of the journal *Archives of Environmental Health*.

Dr. Miller and co-investigator Dr. Howard Mitzel surveyed 112 people who say they developed multiple chemical sensitivity after being exposed to chemicals. Participants were from 33 states and three foreign countries.

Patients with multiple chemical sensitivity report a wide range of symptoms such as shortness of breath, headaches, memory difficulties, depressed feelings and gastrointestinal difficulties. No laboratory tests exist to confirm the diagnosis and the symptoms overlap those of asthma, chronic fatigue syndrome, fibromyalgia, depression and certain psychiatric disorders. Multiple chemical sensitivity also is being examined in investigations of Gulf War Syndrome, an unexplained illness said to affect thousands of Persian Gulf veterans.

Participants in the study were limited to those who were able to trace the origin of their illness to a specific chemical exposure. A total of 37 said they were exposed to pesticides, mostly from household or office exterminations; the remaining 75 said they became ill in a remodeled building. Remodeling often involves new carpet, paint and furnishings that release low levels of solvents. About six in 10 people who said they had become ill in a remodeled building reported that new carpeting had been laid.

"The most striking thing is that 99 percent of these exposures happened to people in their homes or at the office. They did not have to go out of their way to be exposed to chemicals that may have contributed to their illness," Dr. Miller said.

The findings suggest that even low levels of common chemicals may be a health threat to certain individuals. Illnesses were most severe in the group exposed to organophosphate pesticides. These include chlorpyrifos, diazinon, malathion and carbaryl. These pesticides inhibit cholinesterase, an enzyme that is essential for the transmission of nerve signals, but may affect the nervous system in other ways as well.

The group of individuals exposed in remodeled buildings reported less severe symptoms, but the pattern of their illness was almost identical to those with pesticide exposures.

"There is a sad aspect to the study because we discovered that most of the people we surveyed have had to quit their jobs, or at least change jobs, because of their illness. In addition, 40 percent of these people said they had seen 10 or more doctors without any real improvement," Dr. Miller said.

Foods and chemical inhalants such as fragrances, vehicle exhaust and paint vapors seemed to trigger recurrent bouts with the illness. "Overall, members in the pesticides group reported that their symptoms were more severe. This may be because of the relatively greater neurotoxicity of potency for this class of pesticides compared with low levels of solvents associated with remodeling," Dr. Miller said.

"It is noteworthy that both the group exposed to pesticides and the group exposed to remodeling activities developed such strikingly similar patterns of illness. These similarities suggest the existence of a common pathway of toxicity leading to MCS, where exposure to chemically different substances initiates the same process."

Dr. Miller is an assistant professor of environmental and occupational medicine in the department of family practice. She is a member of the Department of Veterans Affairs (VA) Persian Gulf Expert Scientific Committee and performs medical evaluations of Gulf War veterans for the VA. She and Dr. Nicolas Ashford of the Massachusetts Institute of Technology co-authored the book *Chemical Exposures: Low Levels and High Stakes* and the *New Jersey Report on Chemical Sensitivity*, which won an award from the World Health Organization for its significance for public health policy. Dr. Mitzel is a research methologist and psychometrician.