Multiple chemical sensitivity

Multiple chemical sensitivity (MCS), also known as "20th Century Syndrome", "Environmental illness", "Sick Building Syndrome", Idiopathic Environmental Intolerance (IEI), can be defined as a "chronic, recurring disease caused by a person's inability to tolerate an environmental chemical or class of foreign chemicals" according to the NIH National Institute of Environmental Health Sciences web site. more...

Cullen , et al, of Yale Environmental Medicine have published a definition of MCS, making diagnosis possible. Yale Environmental Health provides a comprehensive evaluation, considering differential diagnosis as well Yale Environmental Health Clinical Services.

MCS etiology is hotly debated among physicians. Professionals are divided: some believe that MCS is a physical illness with a yet-to-be-determined mechanism, some believe that MCS is the result of increase in exposure to irritants or a toxic injury, some believe that MCS is psychosomatic. Despite this debate, however, there is consensus that patients who complain of symptoms are recommended to avoid irritants as best as possible. Respect in care and recommendation of avoidance of irritants is now standard protocol recommended by the American Medical Association.

Several chemical-producing companies, especially producers of pesticides, have also funded studies that have cast doubts on the existence and cause of MCS.

Just as physicians debate etiology, those with MCS do not all agree on causation. While many with MCS believe that they have been injured by overexposure to chemicals, some believe that they have developed an intolerance over time, and still others are uncertain as to the cause and are open to a yet-to-be-determined mechanism. What is clear and agreed upon is that exposure to chemical irritants precipitates sometimes disabling symptoms such as migraine headache, sinus congestion, itchy eyes and throat, nausea and vomiting.

MCS is a non-coded medical diagnosis in the United States. Conventional medicine does not typically recognize this diagnosis, because to date there is no definitive test for diagnosis or proven scientific mechanism. Symptoms may be explainable by allergic, metabolic, enzymatic, inflammatory,infectious, or psychological mechanism.

Preliminary scientific testing has been unable to validate the correlation of symptoms with exposure to chemicals. Because the nature and cause(s) of MCS are still unanswered, effective testing may not yet be available. Complications may include propellants and other chemicals in the testing environment. In one blinded test, patients appeared to show no reaction to suspected substances. The same patients also seemed to react to saline solution injections and purified air injected into their environment. However, there has not been sufficient analysis to challenge or verify these tests.

Allergist Theron G. Randolph (1906-1995) is generally seen as the 'inventor' of the term and introducing this condition to the public. It was he who first speculated that exposure to modern synthetic chemicals was the cause. Allergic reactions to minute traces of chemicals goes against what is known about the correlation between dose and effect. Randolph, however, theorized that the human body is like a barrel filling up with small or even minute doses of chemicals until it is full. Any further exposure will then cause allergic reactions, like the straw that broke the camel's back. Science recognizes that there are chemicals that build up in the body (such as mercury), but these do not cause allergic reactions. They can, though, cause organ failure, such as failure of the liver (which is involved in storing these chemicals) or the kidneys (involved in filtering them out). Some chemicals are also stored in body fat. These effects have never been found in MCS patients, either suggesting that they actually do not suffer from the effects of chemicals or that there is another mechanism (possibly the one Randolph proposed) to blame for their symptoms. People who treat MCS generally identify themselves as "clinical ecologists", and many belong to the American Academy of Environmental Medicine, which Randolph founded in 1965 as the Society for Clinical Ecology. Clinical Ecology is not a recognised field of medical science.

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