MCS is a controversial diagnosis and is not recognized as an organic, chemical-caused illness by the American Medical Association or other authorities.[1] Blinded clinical trials have shown MCS patients react as often and as strongly to placebos, including clean air,[2][3] as they do to the chemicals they say harm them. This has led some experts to believe MCS symptoms are due to odor hypersensitivity[4] or are mainly psychological.
The International Statistical Classification of Diseases and Related Health Problems (ICD), maintained by the World Health Organization, does not recognize multiple chemical sensitivity or environmental sensitivity as a valid diagnosis.[13]
The American Medical Association (AMA) has stated that because of the lack of scientific evidence, based on well-controlled clinical trials, that supports a cause-and-effect relationship between exposure to very low levels of chemicals and the myriad symptoms reported by clinical ecologists, MCS is not recognized as an established organic disease. The American Academy of Allergy, Asthma, and Immunology, the California Medical Association, the American College of Physicians, and the International Society of Regulatory Toxicology and Pharmacology also do not recognise it.[1][14][15] In 1994, the AMA, American Lung Association, US EPA and US Consumer Product Safety Commission published a booklet on indoor air pollution that discusses MCS, among other issues. Although sometimes misrepresented as evidence these groups recognize MCS as a specific disease, the booklet states a pathogenesis of MCS has not been definitively proven. The booklet further states symptoms that have been self-diagnosed by a patient as related to MCS could actually be related to allergies or have a psychological basis.
Ronald E. Gots, M.D., an environmental toxicologist and frequent defense consultant in toxic tort litigation,[17] describes MCS as "a label given to people who do not feel well for a variety of reasons and who share the common belief that chemical sensitivities are to blame. ... It has no consistent characteristics, no uniform cause, no objective or measurable features. It exists because a patient believes it does and a doctor validates that belief."[18] In editorial in the Journal of Toxicology - Clinical Toxicology Gots wrote, "The phenomenon of multiple chemical sensitivities is a peculiar manifestation of our technophobic and chemophobic society. ... It may be the only ailment in existence in which the patient defines both the cause and the manifestations of his own condition."[1]