Multiple chemical sensitivity

In nosological terms, MCS may be more than one disease. Being more sensitive than average to some chemical exposures (e.g., secondhand smoke) is fairly common. Other names, such as idiopathic environmental intolerance, have been recommended as more accurate alternatives. For example, the 1987 definition that requires symptoms to begin suddenly after an identifiable, documented exposure to a chemical, but the 1996 definition by the WHO/ICPS says that the cause can be anything, including other medical conditions or psychological factors. In 1996, an expert panel at WHO/ICPS was set up to examine MCS. The panel accepted the existence of "a disease of unclear pathogenesis", rejected the claim that MCS was caused by chemical exposure, and proposed these three diagnostic requirements for a group of conditions that includes MCS, which they called idiopathic environmental intolerances (IEI): • the disease was acquired (not present from birth) and must produce multiple relapsing symptoms; • the symptoms must be closely related to "multiple environmental influences, which are well tolerated by the majority of the population"; and • it could not be explained by any other medical condition. The defined lab findings are abnormalities in parasympathetic nerves, cerebral cortical dysfunction diagnosed by SPECT testing, visuospatial abnormalities, abnormalities of eye movement, or a positive provocation test. For example, this could describe someone who always feels sick after using ordinary household cleaning products, when exposed to new car smell, or having a live Christmas tree in the house, and then feels better again when not around these things. Additionally, the symptoms cannot be explainable through other conditions that can be identified with ordinary medical tests, such as an allergic reaction. == Symptoms ==

Symptoms are typically vague and non-specific, such as fatigue or headaches. These symptoms, although they can be disabling, are called non-specific because they are not associated with any single specific medical condition. Symptoms affect a variety of different organ systems. Different people have different symptoms and different affected systems, but cognitive and neurologic symptoms (e.g., headache and brain fog) are common, as are systemic symptoms (e.g., fatigue). == Possible causes ==

Various different causes for MCS have been hypothesized, including immunological, toxicological, and neurobiological ideas. There is a general agreement among most MCS researchers that the cause is not specifically related to sensitivity to chemicals, but this does not preclude the possibility that symptoms are caused by other known or unknown factors. Various health care professionals and government agencies are working on giving those who report the symptoms proper care while searching for a cause. In 2017, a Canadian government Task Force on Environmental Health said that there had been very little rigorous peer-reviewed research into MCS and almost a complete lack of funding for such research in North America. "Most recently," it said, "some peer-reviewed clinical research has emerged from centres in Italy, Denmark and Japan suggesting that there are fundamental neurobiologic, metabolic, and genetic susceptibility factors that underlie ES/MCS." Immunological Researchers have studied immunity biomarkers in people with MCS to determine whether MCS could be an autoimmune disorder or allergic response, but the results have been inconclusive. Some people with MCS appear to have excess production of inflammatory cytokines, but this phenomenon is not specific to MCS and overall there is no evidence that low-level chemical exposure causes an immune response. == Diagnosis ==

In practice, diagnosis relies entirely upon the self-reported claim that the symptoms are triggered by exposure to various substances. Commonly attributed substances include scented products (e.g. perfumes), pesticides, plastics, synthetic fabrics, smoke, petroleum products, and paint fumes. Many other tests have been promoted by various people over the years, including testing of the immune system, porphyrin metabolism, provocation-neutralization testing, autoantibodies, the Epstein–Barr virus, testing for evidence of exposure to pesticides or heavy metals, and challenges involving exposure to chemicals, foods, or inhalants. None of these tests correlate with MCS symptoms, and none are useful for diagnosing MCS. The stress and anxiety experienced by people reporting MCS symptoms are significant. Neuropsychological assessments do not find differences between people reporting MCS symptoms and other people in areas such as verbal learning, memory functioning, or psychomotor performance. Neuropsychological tests are sensitive but not specific, and they identify differences that may be caused by unrelated medical, neurological, or neuropsychological conditions. Another major goal for diagnostic work is to identify and treat any other medical conditions the person may have. People reporting MCS-like symptoms may have other health issues, ranging from common conditions, such as depression or asthma, to less common circumstances, such a documented chemical exposure during a work accident. These other conditions may or may not have any relationship to MCS symptoms, but they should be diagnosed and treated appropriately, whenever the patient history, physical examination, or routine medical tests indicates their presence. The differential diagnosis list includes solvent exposure, occupational asthma, and allergies. ==Management==

There is no single proven treatment for MCS == Epidemiology ==

Prevalence rates for MCS vary according to the diagnostic criteria used. For example, a 2014 study estimated that 0.9% of Canadian males and 3.3% of Canadian females had a diagnosis of MCS by a health professional. In Germany, 9% of adults say they have MCS, and 12% of adults in the US say they have been diagnosed. , women are far more likely to have MCS. The condition is reported across industrialized countries. It affects significantly more women than men. A typical age of onset is near middle age. People with MCS are more likely to have high socioeconomic status and to be well educated. They are also more likely to have stressful work situations and a history of subjective health complaints. For about half of people with MCS, the symptoms could be considered disabling. Related syndromes Symptoms attributed to Gulf War syndrome are similar to those reported for MCS, including headache, fatigue, muscle stiffness, joint pain, inability to concentrate, sleep problems, and gastrointestinal issues. Gulf War veterans are somewhat more likely to have symptoms consistent with MCS. MCS is also similar to sick building syndrome, with both showing non-specific symptoms such as headaches, respiratory irritation and fatigue. There is also some overlap in symptoms between MCS and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), though chemical exposures are not suspected in ME/CFS. == Prognosis ==

About half of those with MCS get better over the course of several years, while about half continue to experience distressing or disabling symptoms. == History ==

MCS was first proposed as a distinct disease by Theron G. Randolph in 1950. In 1965, Randolph founded the Society for Clinical Ecology as an organization to promote his ideas about symptoms reported by his patients. As a consequence of his insistence upon his own, non-standard definition of allergy and his unusual theories about how the immune system and toxins affect people, the ideas he promoted were widely rejected, and clinical ecology emerged as a non-recognized medical specialty. In 1994, the AMA, American Lung Association, US EPA and the US Consumer Product Safety Commission published a booklet on indoor air pollution that discusses MCS, among other issues. The booklet further states that a pathogenesis of MCS has not been definitively proven, and that symptoms that have been self-diagnosed by a patient as related to MCS could actually be related to allergies or have a psychological basis, and recommends that physicians should counsel patients seeking relief from their symptoms that they may benefit from consultation with specialists in these fields. In 1995, an Interagency Workgroup on Multiple Chemical Sensitivity was formed under the supervision of the Environmental Health Policy Committee within the United States Department of Health and Human Services to examine the body of research that had been conducted on MCS to that date. The work group included representatives from the Centers for Disease Control and Prevention, United States Environmental Protection Agency, United States Department of Energy, Agency for Toxic Substances and Disease Registry, and the National Institutes of Health. The Predecisional Draft document generated by the workgroup in 1998 recommended additional research in the basic epidemiology of MCS, the performance of case-comparison and challenge studies, and the development of a case definition for MCS. However, the workgroup also concluded that it was unlikely that MCS would receive extensive financial resources from federal agencies because of budgetary constraints and the allocation of funds to other, extensively overlapping syndromes with unknown cause, such as chronic fatigue syndrome, fibromyalgia, and Gulf War syndrome. The Environmental Health Policy Committee is currently inactive, and the workgroup document has not been finalized. The different understandings of MCS over the years have also resulted in different proposals for names. while another researcher, whose definition includes people with allergies and acute poisoning, calls it chemical sensitivity. == Society and culture ==

Memoirs about multiple chemical sensitivity tend to follow a predictable pattern, with a description of various toxins and their effects alongside requests for others to help the writers by changing their behavior (e.g., by not wearing perfume). Frequently the memoirs focus more on things than on people, with interpersonal relationships fading into the background as the writers describe the vigilance they apply to everyday life, such as holding their breath whenever a car drives by, or trying to guess whether nearby people are likely to be smoking or wearing perfumes. International Statistical Classification of Diseases The International Statistical Classification of Diseases and Related Health Problems (ICD), maintained by the World Health Organization, is a medical coding system used for medical billing and statistical purposes – not for deciding whether any person is sick, or whether any collection of symptoms constitutes a single disease. However, this does not mean that people with MCS-related symptoms cannot be treated or billed for medical services.MCS was illegally, without a proper proposal, added to USA ICD10 medical diagnostic code system 2011-2016, then, it was removed. https://icd.codes/icd10cm/F459# The public health service in Germany permits healthcare providers to bill for MCS-related medical services under the ICD-10 code T78.4, which is for idiosyncratic reactions, classified under the heading T78, Unerwünschte Nebenwirkungen, anderenorts nicht klassifiziert ("adverse reactions, not otherwise specified"). Being able to get paid for medical services and collect statistics about unspecified, idiosyncratic reactions does not mean that MCS is recognized as a specific disease or that any particular cause has been defined by the German government. MCS is named in evidence-based ("S3") guidelines for the management of patients with nonspecific, functional symptoms. ==See also==