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{{Short description|Controversial medical diagnosis}} | |||
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'''Multiple chemical sensitivity''' ('''MCS'''), also known as '''idiopathic environmental intolerances''' ('''IEI'''), is a ] characterized by ] that the affected person attributes to encountering small amounts of common substances, such as ]. The etiology, diagnosis and treatment of MCS are controversial and still debated among researchers, but a 2018 ] concluded that the evidence suggests that organic abnormalities in ] pathways and the ] combined with some specific, uncommon ] (such as heightened ]) best explains this condition.<ref name="pmid30088144"/> | |||
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{{Update|reason=Over half of the sources were published more than 10 years ago. ] prefers sources within the last 5 years or so|date=May 2024}} | |||
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<!--Definition and symptoms--> | |||
'''Multiple chemical sensitivity''' ('''MCS''') is an underrecognized diagnosis characterized by chronic ] attributed to exposure to low levels of commonly used chemicals.<ref name="Genuis2013">{{Cite journal|last1=Genuis|first1=SJ|date=May 2013|title=Chemical sensitivity: pathophysiology or pathopsychology?|journal=Clinical Therapeutics|volume=35|issue=5|pages=572–7|doi=10.1016/j.clinthera.2013.04.003|pmid=23642291}}</ref><ref name="Templeton">{{Citation |last1=Templeton |first1=Douglas M. |last2=Schwenk |first2=Michael |last3= Duffus |first3=John H. |date=2016 |title=Multiple Chemical Sensitivity (MCS) |work=] Glossary of Terms Used in Neurotoxicology |publisher=] |url=https://www.researchgate.net/publication/286049129 |doi=10.1515/pac-2015-0103 |quote=multiple chemical sensitivity (MCS) -environmental illness -idiopathic environmental intolerance -Intolerance condition attributed to extreme sensitivity of individuals to various environmental chemicals, found in air, food, water, building materials, or fabrics. Note 1: This syndrome is characterized by the patient’s belief that his or her symptoms are caused by very low-level exposure to environmental chemicals. The term “chemical” is used to refer broadly to many natural and man-made substances, some of which have several chemical constituents. Note 2: ... }}</ref> Symptoms are typically ] and ]. They may include ], ]s, ], respiratory problems, seizures, confusion, lethargy, pain, and ]. | |||
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Commonly attributed substances for MCS symptoms include scented products, ]s, plastics, synthetic fabrics, smoke, ] products, and paint fumes.<ref name=Genuis2013>{{cite journal|last1=Genuis|first1=SJ|title=Chemical sensitivity: pathophysiology or pathopsychology?|journal=Clinical Therapeutics|date=May 2013|volume=35|issue=5|pages=572–7|doi=10.1016/j.clinthera.2013.04.003|pmid=23642291|type=Review}}</ref> | |||
Recent imaging studies have shown that it is likely a ] condition.<ref>{{Cite journal |last1=Molot |first1=John |last2=Sears |first2=Margaret |last3=Anisman |first3=Hymie |date=2023-08-01 |title=Multiple chemical sensitivity: It's time to catch up to the science |journal=Neuroscience & Biobehavioral Reviews |volume=151 |pages=105227 |doi=10.1016/j.neubiorev.2023.105227 |pmid=37172924 |issn=0149-7634|doi-access=free }}</ref> | |||
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MCS is not recognized as a separate, discrete disease by the ], ], or by several other professional medical organizations.<ref name=Sears /><ref name="Gots"/> | |||
MCS is a ] that requires ongoing management. In the long term, about half of people with MCS get better and about half continue to be affected, sometimes severely.<ref name="Current 2021" /> | |||
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== |
== Classification == | ||
In ] terms, MCS may be more than one disease.<ref name="Linde">{{Cite book |last1=Linde |first1=Brian |url=https://onlinelibrary.wiley.com/doi/book/10.1002/0471435139 |title=Patty's Industrial Hygiene |last2=Redlich |first2=Carrie A. |date=10 February 2021 |publisher=Wiley |isbn=978-0-471-29784-0 |editor-last=Harris |editor-first=Robert |edition=7th |language=en |chapter=Symptomatic Responses to Low-Level Occupational and Environmental Exposures |doi=10.1002/0471435139.hyg013.pub3 |via=<!-- available in ] -->}}</ref><ref name="Current 2021" /> | |||
Symptoms range in severity from mild to disabling. | |||
It is generally considered a subtype of non-allergic ] (also called ''chemical sensitivity'').<ref name="Linde2">{{Cite book |last1=Linde |first1=Brian |url=https://onlinelibrary.wiley.com/doi/book/10.1002/0471435139 |title=Patty's Industrial Hygiene |last2=Redlich |first2=Carrie A. |date=10 February 2021 |publisher=Wiley |isbn=978-0-471-29784-0 |editor-last=Harris |editor-first=Robert |edition=7th |language=en |chapter=Symptomatic Responses to Low-Level Occupational and Environmental Exposures |doi=10.1002/0471435139.hyg013.pub3 |via=<!-- available in ] -->}}</ref> | |||
Symptoms are common, but ] and ] for the condition. The most common are ], "brain fog" (short-term memory problems, difficulty concentrating), gastrointestinal problems, headaches, and ].<ref name="Genuis2013"/> | |||
MCS is considered an ], meaning that it was not present from birth but instead developed later.<ref name="Linde" /> | |||
A partial list of other symptoms patients have attributed to MCS include: ], pains in the throat, chest, or abdominal region, skin irritation, ], neurological symptoms (], ] feelings, ], trembling, ]), ], ]s, visual disturbances (blurring, halo effect, inability to focus), ], panic, anger, sleep disturbance, suppression of the immune system, digestive difficulties, ], ]/], ], ], joint pains, ]/dizziness, abnormally acute sense of smell (]), sensitivity to natural plant fragrance or natural pine ]s, dry mouth and eyes, and an overactive bladder.<ref name="Genuis2013"/><ref>{{cite journal |vauthors=Ross PM, Whysner J, Covello VT, Kuschner M, Rifkind AB, Sedler MJ, Trichopoulos D, Williams GM | year = 1999 | title = Olfaction and Symptoms in the Multiple Chemical Sensitivities Syndrome | url = | journal = Preventive Medicine | volume = 28 | issue = 5| pages = 467–480 | pmid = 10329337 | doi=10.1006/pmed.1998.0469}}</ref><ref>{{cite journal |vauthors=Graveling RA, Pilkington A, George JP, Butler MP, Tannahill SN | year = 1999 | title = A review of multiple chemical sensitivity | url = | journal = Occupational and Environmental Medicine | volume = 56 | issue = 2| pages = 73–85 | pmid = 10448311 | pmc=1757696 | doi=10.1136/oem.56.2.73}}</ref> | |||
Compared to other conditions with ], such as ], ] or ], MCS symptoms are only present in response to environmental triggers.<ref name="Linde" /> | |||
== Causes == | |||
There is no clear consensus for the cause or causes of the symptoms of MCS. A 2007 ] paper defined MCS as a "chronic, recurring disease caused by a person's inability to tolerate an environmental chemical or class of foreign chemicals".<ref name=NIEHSFAQ> — United States National Institute of Environmental Health Sciences</ref> A 2018 systematic review concluded that the evidence suggests that abnormalities in sensory processing pathways combined with peculiar personality traits best explains this condition.<ref name="pmid30088144">{{Cite journal | last1 = Viziano | first1 = A. | last2 = Micarelli | first2 = A. | last3 = Pasquantonio | first3 = G. | last4 = Della-Morte | first4 = D. | last5 = Alessandrini | first5 = M. | title = Perspectives on multisensory perception disruption in idiopathic environmental intolerance: a systematic review. | journal = Int Arch Occup Environ Health | volume = 91 | issue = 8 | pages = 923–935 | date = November 2018 | doi = 10.1007/s00420-018-1346-z | PMID = 30088144 }}</ref> | |||
=== Name === | |||
In addition to extreme sensitivity to low concentrations of certain chemicals, several hypotheses have been proposed. The distinction between physiological and psychological causes is often difficult to test,<ref name="Das-Munshi2006">{{cite journal |last1=Das-Munshi |first1=J |last2=Rubin |first2=GJ |last3=Wessely |first3=S |title=Multiple chemical sensitivities: A systematic review of provocation studies. |journal=The Journal of Allergy and Clinical Immunology |date=December 2006 |volume=118 |issue=6 |pages=1257-64 |pmid=17137865}}</ref> and it is particularly challenging for MCS because many substances used to test for sensitivity have a strong odor. Odor cues make ] studies of MCS patients difficult, as scents can provoke a ] or recall expectations and prior beliefs.<ref name="Das-Munshi2006"/> | |||
The name ''multiple chemical sensitivity'' has been criticized, partly because MCS is not a ] in the ] or immunological meaning of that word.<ref name="Linde">{{Cite book |last1=Linde |first1=Brian |url=https://onlinelibrary.wiley.com/doi/book/10.1002/0471435139 |title=Patty's Industrial Hygiene |last2=Redlich |first2=Carrie A. |date=10 February 2021 |publisher=Wiley |isbn=978-0-471-29784-0 |editor-last=Harris |editor-first=Robert |edition=7th |language=en |chapter=Symptomatic Responses to Low-Level Occupational and Environmental Exposures |doi=10.1002/0471435139.hyg013.pub3 |via=<!-- available in ] -->}}</ref> Being more sensitive than average to some chemical exposures (e.g., ]) is fairly common.<ref name="Linde" /> MCS is generally used to refer to more significant disability.<ref name="Linde" /> | |||
The name has also been criticized because it suggests that chemical exposure is the actual cause or ], which has not been proven. The word ''chemical'' in the name is used loosely and includes natural substances (e.g., the aromas produced by pine trees or other fragrant plants).<ref name="Templeton" /> Other names, such as ], have been recommended as more accurate alternatives.<ref name="Linde" /> | |||
=== Chemical triggers === | |||
Many chemicals have been reported to trigger MCS symptoms.<ref name="Magill" /> Substances with strong scents are the most commonly reported triggers. These include a variety of cleaning agents, pesticides, perfumes, vehicle exhaust, the products used in barber shops and beauty salons, new carpeting, new furniture, chlorine and fluoride in drinking water, fresh ink, and less commonly wood smoke and secondhand tobacco smoke.<ref>Chemical Sensitivity. American Academy of Environmental Medicine Position Paper. Oct 29, 2008. https://www.aaemonline.org/chemicalsensitivity.php</ref> Food items reported as triggers include ] (a.k.a. FD&C Yellow #5 or E102), and other ]s<ref>{{Cite journal | pmid = 17075259| year = 2006| author1 = Inomata| first1 = N| title = Multiple chemical sensitivities following intolerance to azo dye in sweets in a 5-year-old girl| journal = Allergology International| volume = 55| issue = 2| pages = 203–5| last2 = Osuna| first2 = H| last3 = Fujita| first3 = H| last4 = Ogawa| first4 = T| last5 = Ikezawa| first5 = Z| doi = 10.2332/allergolint.55.203}}</ref> (in the absence of an ]), ], and ].<ref>{{cite journal |author=Pall ML |title=NMDA sensitization and stimulation by peroxynitrite, nitric oxide, and organic solvents as the mechanism of chemical sensitivity in multiple chemical sensitivity |journal=FASEB J. |volume=16 |issue=11 |pages=1407–17 |date=September 2002 |pmid=12205032 |doi=10.1096/fj.01-0861hyp |url=}}</ref> | |||
=== |
=== Definitions === | ||
Different researchers and proponents use different definitions, which complicates research and can affect diagnosis.<ref name="International Programme">{{Cite web |last=International Programme on Chemical Sensitivity |date=February 1996 |title=Report of Multiple Chemical Sensitivities Workshop |url=https://apps.who.int/iris/bitstream/handle/10665/63109/PCS_96.29.pdf |access-date=11 June 2020 |location=Berlin, Germany}}</ref>{{Obsolete source|reason=] prefers sources within the last 5 years or so|date=May 2024}} For example, the 1987 definition that requires symptoms to begin suddenly after an identifiable, documented exposure to a chemical,<ref name="Rossi">{{Cite journal |last1=Rossi |first1=Sabrina |last2=Pitidis |first2=Alessio |date=February 2018 |title=Multiple Chemical Sensitivity: Review of the State of the Art in Epidemiology, Diagnosis, and Future Perspectives |journal=Journal of Occupational and Environmental Medicine |language=en-US |volume=60 |issue=2 |pages=138–146 |doi=10.1097/JOM.0000000000001215 |issn=1076-2752 |pmc=5794238 |pmid=29111991}}</ref> but the 1996 definition by the WHO/ICPS says that the cause can be anything, including other medical conditions or psychological factors.<ref name="Rossi" /><ref name=":1">{{Cite journal |last=Katoh |first=Takahiko |date=2018 |title=Multiple Chemical Sensitivity (MCS): History, Epidemiology and Mechanism |trans-title=Multiple Chemical Sensitivity (MCS): History, Epidemiology and Mechanism |journal=Nihon Eiseigaku Zasshi (Japanese Journal of Hygiene) |language=ja |volume=73 |issue=1 |pages=1–8 |doi=10.1265/jjh.73.1 |issn=1882-6482 |pmid=29386440 |doi-access=free}}</ref> | |||
One proposed hypothesis for the cause of multiple chemical sensitivity is immune system dysfunction after being sensitized by a chemical exposure.<ref name="Genuis2013"/> | |||
In 1996, an expert panel at WHO/ICPS was set up to examine MCS.<ref name="Schwenk">{{Cite journal |last1=Schwenk |first1=Michael |date=2004 |title=Multiple Chemical Sensitivity (MCS) - Scientific and Public-Health Aspects |journal=GMS Current Topics in Otorhinolaryngology, Head and Neck Surgery |volume=3 |pages=Doc05 |issn=1865-1011 |pmc=3199799 |pmid=22073047}}</ref>{{Obsolete source|reason=] prefers sources within the last 5 years or so|date=May 2024}} 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): | |||
=== Psychological === | |||
<!-- DO NOT DELETE JUST BECAUSE YOU DISAGREE. See the Talk page for more information. --> | |||
Several mechanisms for a psychological etiology have been proposed, including theories based on misdiagnoses of an underlying mental illness, stress, or ]. Many people with MCS meet the criteria for ] or ].<ref name=Lax /> Other proposed explanations include ],<ref name="pmid16314597">{{cite journal |vauthors=Bailer J, Witthöft M, Paul C, Bayerl C, Rist F |title=Evidence for overlap between idiopathic environmental intolerance and somatoform disorders |journal=] |volume=67 |issue=6 |pages=921–9 |year=2005 |pmid=16314597 |doi=10.1097/01.psy.0000174170.66109.b7 |url=http://www.psychosomaticmedicine.org/cgi/pmidlookup?view=long&pmid=16314597}}</ref>{{primary source inline|date=June 2019}} ],<ref>{{cite journal |vauthors=Binkley KE, Kutcher S | year = 1997 | title = Panic response to sodium lactate infusion in patients with multiple chemical sensitivity syndrome | url = | journal = J Allergy Clin Immunol | volume = 99 | issue = 4| pages = 570–4 | doi=10.1016/s0091-6749(97)70086-1| pmid = 9111504 }}</ref>{{primary source inline|date=June 2019}} ], ], or ], where symptoms such as brain fog and headaches can be triggered by chemicals or inhalants. Through behavioral conditioning, they may develop real, but unintentionally psychologically produced, symptoms such as anticipatory nausea when they encounter certain odors or other perceived triggers.<ref>{{Cite journal|title = Review of evidence for a toxicological mechanism of idiopathic environmental intolerance|journal = Human & Experimental Toxicology|date = 2013-01-01|issn = 1477-0903|pmid = 23060407|pages = 3–17|volume = 32|issue = 1|doi = 10.1177/0960327112457189|first = Lh|last = Hetherington|first2 = Jm|last2 = Battershill}}</ref> Affected individuals may also have a tendency to "catastrophically misinterpret benign physical symptoms"<ref name="titleMedscape & eMedicine Log In">{{cite web |url=http://www.medscape.com/viewarticle/411615 |title= Idiopathic Environmental Intolerance May Have Psychological Component|publisher=Medscape.com |accessdate=2008-01-13 }}</ref> or simply have a disturbingly acute sense of smell.{{medical citation needed|date=June 2019}} The personality trait ], in which individuals are predisposed to becoming deeply immersed in sensory experiences, may be stronger in individuals reporting symptoms of MCS.<ref>{{cite journal |vauthors=Witthöft M, Rist F, Bailer J |title=Evidence for a specific link between the personality trait of absorption and idiopathic environmental intolerance |journal=J. Toxicol. Environ. Health Part A |volume=71 |issue=11–12 |pages=795–802 |year=2008 |pmid=18569578 |doi=10.1080/15287390801985687 |url=}}</ref> Behaviors exhibited by MCS sufferers may reflect broader sociological fears about industrial pollution and broader societal trends of ] and ].<ref name="Gots">{{cite journal|author=Gots RE|title=Multiple chemical sensitivities--public policy|journal=J. Toxicol. Clin. Toxicol.|volume=33|issue=2|pages=111–3|year=1995|pmid=7897748|quote= The phenomenon of multiple chemical sensitivities is a peculiar manifestation of our technophobic and chemophobic society. It has been rejected as an established organic disease by the American Academy of Allergy and Immunology, the American Medical Association, the California Medical Association, the American College of Physicians, and the International Society of Regulatory Toxicology and Pharmacology. It may be the only ailment in existence in which the patient defines both the cause and the manifestations of his own condition.|doi=10.3109/15563659509000459}}</ref><ref name="Shorter1997">{{cite journal |last1=Shorter |first1=E |title=Multiple chemical sensitivity: pseudodisease in historical perspective |journal=Scandinavian Journal of Work, Environment, and Health |date=1997 |volume=23 |issue=Supplement 3 |pages=35-42 |pmid=9456064}}</ref> | |||
# the disease was acquired (not present from birth) and must produce multiple relapsing symptoms; | |||
=== Neurological === | |||
#the symptoms must be closely related to "multiple environmental influences, which are well tolerated by the majority of the population"; and | |||
People who suffer from MCS may have a neurological dysfunction in the odor-processing areas of the brain<ref>{{cite journal |vauthors=Orriols R, Costa R, Cuberas G, Jacas C, Castell J, Sunyer J |title=Brain dysfunction in multiple chemical sensitivity |journal=J. Neurol. Sci. |volume= 287|issue= 1–2|pages= 72–8|date=October 2009 |pmid=19801154 |doi=10.1016/j.jns.2009.09.003 |url=}}</ref>{{primary source inline|date=June 2019}} or may respond strongly to fumes or scents for some other reason.<ref name="Thriel">{{cite journal |vauthors=van Thriel C, Kiesswetter E, Schäper M, Juran SA, Blaszkewicz M, Kleinbeck S |title=Odor annoyance of environmental chemicals: sensory and cognitive influences |journal=J. Toxicol. Environ. Health Part A |volume=71 |issue=11–12 |pages=776–85 |year=2008 |pmid=18569576 |doi=10.1080/15287390801985596 |url=}}</ref>{{primary source inline|date=June 2019}} | |||
#it ] medical condition.<ref name="Schwenk" />{{Obsolete source|reason=] prefers sources within the last 5 years or so|date=May 2024}} | |||
In Japan, MCS is called ''chemical hypersensitivity'' or ''chemical intolerance'' (<span lang="ja" dir="ltr">化学物質過敏症</span>; kagaku bushitsu kabinsho), and the 1999 Japanese definition requires one or more of four major symptoms – headaches; malaise and fatigue; muscle pain; joint pain – combined with laboratory findings and/or some minor symptoms, such as mental effects or skin conditions.<ref name=":1a">{{Cite web |title=Safety and Health Topics: Multiple Chemical Sensitivities |url=https://www.osha.gov/multiple-chemical-sensitivities |access-date=2021-01-06 |publisher=Occupational Safety and Health Administration}}</ref> The defined lab findings are abnormalities in ], ] dysfunction diagnosed by ] testing, ] abnormalities, abnormalities of ], or a positive ].<ref name=":1" /> | |||
Another definition requires a known precipitating event (e.g., an injury or an illness) followed by the appearance of multi-organ symptoms that predictably wax and wane in response to a variety of exposures that do not bother other people.<ref name="Current 2021">{{Cite book |last=Harrison |first=Robert J. |title=Current Occupational & Environmental Medicine |publisher=McGraw-Hill Education/Medical |year=2021 |isbn=978-1260143430 |edition=Sixth |location=New York |pages=853–860 |chapter=Multiple Chemical Sensitivity |oclc=1250024967}}</ref> For example, this could describe someone who always feels sick after using ordinary household cleaning products, when exposed to ], or having a live ] 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 ], such as an ].<ref name="Current 2021" /> | |||
=== Genetic differences in metabolism === | |||
Genetic differences relating to toxicant metabolism pathways, such as polymorphisms and differences in expression in ], ], ], and ] and ], have been proposed as a cause for differences in susceptibility to MCS.<ref name="McKeown et al. 2004">{{cite journal |vauthors=McKeown-Eyssen G, Baines C, Cole DE, Riley N, Tyndale RF, Marshall L, Jazmaji V | title = Case-control study of genotypes in multiple chemical sensitivity: CYP2D6, NAT1, NAT2, PON1, PON2 and MTHFR | volume = 33| issue = 5 | pages = 971–8 | year = 2004 | pmid = 15256524 | doi = 10.1093/ije/dyh251 | journal = Psychosomatic Medicine }}</ref><ref name="Schnackenberget">Schnackenberg, E. et al. (2007). Environmental Health.</ref>{{primary source inline|date=June 2019}} Elevated ] and ] (NO/ONOO-) could then cause the symptoms of MCS and several related conditions, including fibromyalgia, ], ], and chronic fatigue syndrome.<ref name="Pall 2003">{{cite journal |author=Pall ML |title=Elevated nitric oxide/peroxynitrite theory of multiple chemical sensitivity: central role of N-methyl-D-aspartate receptors in the sensitivity mechanism |journal=Environ. Health Perspect. |volume=111 |issue=12 |pages=1461–4 |date=September 2003 |pmid=12948884 |pmc=1241647 |doi= 10.1289/ehp.5935|url=}}</ref> | |||
== Symptoms == | |||
Symptoms are typically ] and ], such as ] or ]s.<ref name="Canberra">{{Citation|title=A Scientific Review of Multiple Chemical Sensitivity: Identifying Key Research Needs |date=2010 |publisher= National Industrial Chemicals Notification and Assessment Scheme, Australian Government |location=Canberra, Australia |url=http://test.nicnas.gov.au/Media/Latest_News/MCS.asp |archive-url=https://web.archive.org/web/20200307155500/http://test.nicnas.gov.au/Media/Latest_News/MCS.asp |archive-date=2020-03-07 }}</ref> These symptoms, although they can be disabling, are called non-specific because they are not associated with any single specific medical condition. | |||
People with British Gulf War syndrome who used personal organophosphate pesticides may be more likely to report the symptoms of MCS.<ref>{{cite journal |vauthors=Reid S, etal | year = 2001 | title = Multiple Chemical Sensitivity and Chronic Fatigue Syndrome in British Gulf War Veterans | url = | journal = American Journal of Epidemiology | volume = 153 | issue = 6| pages = 604–9 | doi=10.1093/aje/153.6.604| pmid = 11257069 }}</ref> | |||
Symptoms affect a variety of different ]. Different people have different symptoms and different affected systems, but cognitive and neurologic symptoms (e.g., headache and ]) are common, as are ] (e.g., fatigue).<ref name="Linde" /> Other people have symptoms affecting the eyes, ears, and nose (e.g., ]), the respiratory system (e.g., ]), gastrointestinal system (e.g., ]), musculoskeletal system (e.g., ]), or dermatological system (e.g., ]).<ref name="Linde" /> | |||
A 2010 review of MCS literature said that the following symptoms, in this order, were the most reported in the condition: headache, fatigue, confusion, depression, shortness of breath, arthralgia, myalgia, nausea, dizziness, memory problems, gastrointestinal symptoms, respiratory symptoms.<ref name="Canberra" /> | |||
Symptoms mainly arise from the ] (such as ] or ]) or have psychiatric or psychological aspects (such as difficulty concentrating).<ref name="Katoh">{{Cite journal |last=Katoh |first=Takahiko |date=2018 |title=Multiple Chemical Sensitivity (MCS): History, Epidemiology and Mechanism |journal=Nihon Eiseigaku Zasshi |trans-journal=Japanese Journal of Hygiene |language=ja|volume=73|issue=1|pages=1–8|doi=10.1265/jjh.73.1|issn=1882-6482|pmid=29386440|doi-access=free}}</ref> | |||
== Possible causes == | |||
Various different causes for MCS have been hypothesized, including ], ], and ] ideas.<ref name="Templeton" /><ref name=quebec-synth>{{Cite book |language=fr-ca |title=Syndrome de sensibilité chimique multiple, une approche intégrative pour identifier les mécanismes physiopathologiques |date=June 2021 |url=https://www.inspq.qc.ca/sites/default/files/publications/2729-syndrome-sensibilite-chimique-synthese.pdf |publisher=Institut national de santé publique du Québec |type=Synthèse |isbn=978-2-550-88675-4 |vauthors=Carrier G, Tremblay M, Allard R}}</ref> | |||
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.<ref name="Templeton" /><ref name="Toronto">{{Citation|work=Task Force on Environmental Health |date=2017 |url=http://www.health.gov.on.ca/en/common/ministry/publications/reports/environmental_health_2017/task_force_on_environmental_health_report.pdf |title=Time for Leadership: Recognizing and Improving Care for Those with ME/CFS, FM and ES/MCS|location= Toronto, Ontario |publisher= Ministry of Health and Long-Term Care}}</ref> Various health care professionals and government agencies are working on giving those who report the symptoms proper care while searching for a cause.<ref name="Toronto"/> | |||
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.<ref name=":8">{{Citation|work=Task Force on Environmental Health |date=2017 |url=http://www.health.gov.on.ca/en/common/ministry/publications/reports/environmental_health_2017/task_force_on_environmental_health_report.pdf |title=Time for leadership: recognizing and improving care for those with ME/CFS, FM and ES/MCS|location= Toronto, Ontario |publisher= Ministry of Health and Long-Term Care |page=53}}</ref> "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."<ref name=":8" /> | |||
The US ] (OSHA) says that MCS is highly controversial and that there is insufficient scientific evidence to explain the relationship between any of the suggested causes of MCS – it lists "allergy, dysfunction of the immune system, neurobiological sensitization, and various psychological theories" as the suggested causes – and its symptoms.<ref>{{cite web|title=Safety and Health Topics | Multiple Chemical Sensitivities|url=http://www.osha.gov/SLTC/multiplechemicalsensitivities/index.html|access-date=2014-06-08|publisher=Osha.gov}}</ref> | |||
=== Immunological === | |||
Researchers have studied immunity ]s 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 ]s, but this phenomenon is not specific to MCS and overall there is no evidence that low-level chemical exposure causes an immune response.<ref name=quebec-synth/> | |||
=== Genetic === | |||
It has been hypothesized that there is a heritable ] which pre-disposes people to be hypersensitive to low-level chemical exposure and so develop MCS. To investigate, researchers compared the ] of people with MCS, to people without. The results were generally inconclusive and contradictory, thus failing to support the hypothesis.<ref name=quebec-synth/> | |||
Gaétan Carrier and colleagues write that the genetic hypothesis appears implausible when the evidence around it is judged by the ].<ref name=quebec-synth/> | |||
=== Psychological === | |||
{{update section|date=June 2024}} | |||
{{npov section|date=June 2024}} | |||
{{More medical citations needed|section|date=November 2021}} | |||
Many people with MCS also include , ], ], or ] and brain fog. Via toxic exposures, it has been proven that people with MCS may develop real symptoms, such as nausea and headache, when they encounter certain odors or other toxic chemical triggers. From 2011-2016 Multiple Chemical Sensitivity was illegally added to the USA ICD10 medical diagnostic code system. The CDC ICD10 code maintenance supervisor said they have no idea how it got into the system. It was removed in 2011. (Source CDC and https://icd.codes/icd10cm/F459# MCS is often a nerve agent injury symptom of Gulf War Illness and Other War Theaters which was added to CDC ICD10 in 2024. | |||
A 2018 systematic review concluded that the evidence suggests that abnormalities in sensory processing pathways combined with peculiar personality traits best explains this condition.<ref name="pmid30088144">{{Cite journal |last1=Viziano |first1=A. |last2=Micarelli |first2=A. |last3=Pasquantonio |first3=G. |last4=Della-Morte |first4=D. |last5=Alessandrini |first5=M. |date=November 2018 |title=Perspectives on multisensory perception disruption in idiopathic environmental intolerance: a systematic review. |url=https://www.researchgate.net/publication/326880068 |journal=Int Arch Occup Environ Health |volume=91 |issue=8 |pages=923–935 |doi=10.1007/s00420-018-1346-z |pmid=30088144 |bibcode=2018IAOEH..91..923V |s2cid=51936485}}</ref> | |||
== Diagnosis == | == Diagnosis == | ||
{{One source|section|find=multiple chemical sensitivity diagnosis|date=October 2024}} | |||
No ], laboratory test abnormalities, tissue pathology, or course of illness have been identified, and it remains unclear whether symptoms are physiologically or psychologically generated.<ref name=Staudenmayer>{{cite journal |vauthors=Staudenmayer H, Selner JC |title=Failure to assess psychopathology in patients presenting with chemical sensitivities |journal=J. Occup. Environ. Med. |volume=37 |issue=6 |pages=704–9; discussion 710 |date=June 1995 |pmid=7670917 |doi= 10.1097/00043764-199506000-00012|url=}}</ref><ref name=QW>S. Barrett, , 1998</ref> | |||
In practice, diagnosis relies upon the ] claim that the symptoms are triggered by exposure to various substances.<ref name="Current">{{Cite book|title=Current Occupational & Environmental Medicine|last=Harrison|first=Robert|publisher=McGraw-Hill Education/Medical|year=2014|isbn=978-0-07-180816-3|edition=Fifth|location=New York|pages=819–826|chapter=Multiple Chemical Sensitivity|oclc=898477589|url=https://archive.org/details/currentoccupatio0000unse_c5n1|quote=controversial methods have been used ... including elimination or rotary diversified diets, vitamins or nutritional supplements, oxygen, antifungal and antiviral agents, thyroid hormone supplement, supplemental estrogen or testosterone, transfer factor, chemical detoxification through exercise and sauna treatment, intravenous gamma-globulin, and intracutaneous or subcutaneous neutralization. A specially designed chemical-free environmental control unit has been used as a method to decrease blood pesticide levels and ... Controversial treatment methods offer hope of improvement to many individuals with MCS, and some patients do report symptom improvement over time. Many ... are expensive and rarely are covered by health insurance. These treatment methods have not been validated through carefully designed, controlled trials, may have unwanted side effects ... page 826}}</ref> In 1999, Dr. Claudia Miller and Dr. Thomas Prihoda of the ] in San Antonio developed the Quick Environmental Exposure and Sensitivity Inventory (QEESI) questionnaire to help physicians standardize such reported symptoms.<ref>{{Cite web |last=Miller and Prihoda |first=Claudia and Thomas |date=March 1999 |title=The Environmental Exposure and Sensitivity Inventory (EESI): a standardized approach for measuring chemical intolerances for research and clinical applications |url=https://www.researchgate.net/publication/309884686_The_Environmental_Exposure_and_Sensitivity_Inventory_EESI_a_standardized_approach_for_measuring_chemical_intolerances_for_research_and_clinical_applications |website=ResearchGate, Toxicology and Industrial Health}}</ref> <ref>{{Cite web |title=Chemical Intolerance Self Assessment |url=https://tiltresearch.org/self-assessment/ |access-date=2024-12-29 |website=Hoffman Program for Chemical Intolerance |language=en-US}}</ref> | |||
Commonly attributed substances include scented products (e.g. perfumes, air fresheners and laundry products), ]s, plastics, synthetic fabrics, smoke, ] products, and paint fumes.<ref name="Genuis2013" /> | |||
===International Classification of Diseases=== | |||
The ] (ICD), maintained by the ], does not recognize multiple chemical sensitivity or environmental sensitivity as a valid diagnosis.<ref name=Sears /> The ] does not recognize MCS as an ] because of the lack of scientific evidence supporting a cause-and-effect relationship between very low level exposure and the symptoms of MCS. The ], the ], the ], and the International Society of Regulatory Toxicology and Pharmacology also do not recognize MCS.<ref name="Gots"/><ref name="Magill">{{cite journal|vauthors=Magill MK, Suruda A |title=Multiple chemical sensitivity syndrome|journal=Am Fam Physician|volume=58|issue=3|pages=721–8|date=September 1998|pmid=9750540|url=http://www.aafp.org/afp/980901ap/magill.html}}</ref><ref name="AMA">{{cite journal|author= Council on Scientific Affairs, American Medical Association|title=Clinical ecology.|journal=JAMA|volume=268|issue=24|pages=3465–7|year=1992|pmid=1460738|quote="No evidence based on well-controlled clinical trials is available that supports a cause-and-effect relationship between exposure to very low levels of substances and the myriad symptoms reported by clinical ecologists to result from such exposure.… Until such accurate, reproducible, and well-controlled studies are available, the American Medical Association Council on Scientific Affairs believes that multiple chemical sensitivity should not be considered a recognized clinical syndrome."|doi= 10.1001/jama.268.24.3465}}</ref> The US ] (OSHA) indicates that MCS is highly controversial and that there is insufficient scientific evidence to explain the relationship between the suggested causes of MCS and its symptoms. OSHA recommends evaluation by a physician knowledgeable of the symptoms presented.<ref>{{cite web|url=http://www.osha.gov/SLTC/multiplechemicalsensitivities/index.html |title=Safety and Health Topics | Multiple Chemical Sensitivities |publisher=Osha.gov |date= |accessdate=2014-06-08}}</ref> | |||
Many other tests have been promoted by various people over the years, including testing of the immune system, ], provocation-neutralization testing, ], the ], testing for evidence of exposure to pesticides or heavy metals, and challenges involving exposure to chemicals, foods, or inhalants.<ref name="Current" /> | |||
===Other=== | |||
In response to a ] call for papers at the 5th Paris Appeal Congress of Environmental Idiopathic Intolerance conference that took place in Belgium on 18 May 2015, a report that was generally supportive quoted a number of international practitioners.<ref>{{cite web |url=https://www.avaate.org/IMG/pdf/statement_en_definitif.pdf|title=2015, Brussels International Scientific Declaration on Electro-magnetic Hypersensitivity and Multiple Chemical Sensitivity|date=18 May 2015|publisher=Asociación Vallisoletana de Afectados por Antenas de Telecomunicaciones (Valladolid Spain Association for those affected by radio emissions)|accessdate=2017-02-28}}</ref> This was provisionally accepted by the ], and later found proven by a judge in the case of a plumber in the ].<ref>{{cite web |url=http://politica.elpais.com/politica/2017/02/27/diario_de_espana/1488199731_421013.html#?ref=rss&format=simple&link=link|title=¿Existe el Síndrome de Sensibilidad Química? Un juez cree que sí|publisher=El País newspaper Spain|date=28 Feb 2017|accessdate=2017-02-28}}</ref> | |||
The stress and ] experienced by people reporting MCS symptoms are significant.<ref name="Current" /> ]s do not find differences between people reporting MCS symptoms and other people in areas such as verbal learning, memory functioning, or ].<ref name="Current" /> Neuropsychological tests are ], and they identify differences that may be caused by unrelated medical, neurological, or neuropsychological conditions.<ref name="Current" /> | |||
MCS is a ], and the first step in diagnosing a potential MCS sufferer is to identify and treat all other conditions which are present and which often explain the reported symptoms. For example, depression, allergy, thyroid disorders, orthostatic syndromes, ], ], and anxiety need to be carefully evaluated and, if present, properly treated. The "gold standard" procedure for identifying a person who has MCS is to test response to the random introduction of chemicals the patient has self-identified as relevant. This may be done in a carefully designed challenge booth to eliminate the possibility of contaminants in the room. Chemicals and controls, sometimes called prompts, are introduced in a random method, usually scent-masked. The test subject does not know when a prompt is being given. Objective and subjective responses are measured. Objective measures, such as the ],<ref name=Joffres2005>{{cite journal|vauthors=Joffres MR, Sampalli T, Fox RA |title=Physiologic and symptomatic responses to low-level substances in individuals with and without chemical sensitivities: a randomized controlled blinded pilot booth study |journal=Environ Health Perspect |volume=113|issue=9|pages=1178–83 |pmid=16140624|doi=10.1289/ehp.7198|year=2005|pmc=1280398 }}</ref> indicate psychological arousal, such as fear, anxiety, or anger. Subjective responses include patient self-reports. A diagnosis of MCS can only be justified when the subject cannot consciously distinguish between chemicals and controls, and when responses are consistently present with exposure to chemicals and consistently absent when prompted by a control. | |||
Another major goal for diagnostic work is to identify and treat any other medical conditions the person may have.<ref name="Current" /> People reporting MCS-like symptoms may have other health issues, ranging from common conditions, such as ] or ], to less common circumstances, such a documented chemical exposure during a ].<ref name="Current" /> These other conditions may or may not have any relationship to MCS symptoms, but they should be diagnosed and treated appropriately, whenever the ], ], or routine ]s indicates their presence.<ref name="Current" /> The ] list includes ], ], and allergies.<ref name="Current" /> | |||
A 1999 consensus statement recommends that MCS be diagnosed according to six standardized criteria:<ref name=Sears>Sears, Margaret E. 2007. Note: The opinions expressed in this report are those of the author and do not necessarily reflect the views of the ].</ref><ref name="pmid10444033">{{cite journal |title=Multiple chemical sensitivity: a 1999 consensus |journal=Arch. Environ. Health |volume=54 |issue=3 |pages=147–9 |year=1999 |pmid=10444033 |doi=10.1080/00039899909602251}}</ref> | |||
==Management== | |||
# Symptoms are reproducible with repeated (chemical) exposures | |||
There is no single proven treatment for MCS<ref name="Toronto" /> and no scientific consensus on supportive therapies.<ref name="Toronto" />{{Rp|17}}<ref name="Canberra"/> The literature generally agrees on the need for MCS patients to avoid the specific substances that trigger reactions for them as well as ]s in general, in order to prevent further sensitization.<ref name="Toronto" />{{Rp|17}}<ref name="Canberra"/> The goal of treatment is to improve ], with fewer distressing symptoms and the ability to maintain employment and social relationships, rather than to produce a permanent cure.<ref name="Current" /> | |||
# The condition has persisted for a significant period of time | |||
# Low levels of exposure (lower than previously or commonly tolerated) result in manifestations of the syndrome (i.e. increased sensitivity) | |||
# The symptoms improve or resolve completely when the triggering chemicals are removed | |||
# Responses often occur to multiple chemically unrelated substances | |||
# Symptoms involve multiple-organ symptoms (runny nose, itchy eyes, headache, scratchy throat, ear ache, scalp pain, mental confusion or sleepiness, palpitations of the heart, upset stomach, nausea, diarrhea, abdominal cramping and aching joints). | |||
Some literature recommends a ] treatment approach that takes into account the uncommon personality traits often seen in affected individuals and physiological abnormalities in sensory pathways and the limbic system.<ref name="pmid30088144" /> | |||
== Treatment == | |||
It has been suggested that a ] approach be taken to treating this condition that takes into account peculiar personality traits often seen in affected individuals and physiological abnormalities in sensorary pathways and the limbic system.<ref name="pmid30088144"/> | |||
Common ] strategies include avoiding exposure to known triggers and emotional self-care.<ref name="Current" /> Healthcare providers can provide useful education on the body's natural ability to eliminate and excrete toxins on its own and support positive self-care efforts.<ref name="Current" /> Avoiding triggers, such as by removing smelly cleaning products from the home, can reduce symptoms and increase the person's sense of being able to reclaim a reasonably normal life.<ref name="Current" /> However, for other people with MCS, their efforts to avoid suspected triggers will backfire, and instead produce harmful emotional side effects that interfere with the overall goal of reducing distress and disability.<ref name="Current 2021" /> Treatments that have not been scientifically validated, such as "elimination or rotary diversified diets", hormone supplement and chemical detoxification through ] have been used by people with MCS. "Controversial treatment methods offer hope of improvement to many individuals with MCS.<ref name="Current" />" Unproven treatments can be expensive, may cause side effects, and may be counterproductive.<ref name="Current" /> | |||
In various studies, about one half of the patients who seek medical treatment for symptoms of MCS meet the criteria for ] and ]s.<ref name=Lax>{{cite journal |vauthors=Lax MB, Henneberger PK |title=Patients with multiple chemical sensitivities in an occupational health clinic: presentation and follow-up |journal=Arch. Environ. Health |volume=50 |issue=6 |pages=425–31 |year=1995 |pmid=8572720 |doi= 10.1080/00039896.1995.9935978|url=}}</ref> Because many people eliminate whole categories of food in an effort to reduce symptoms, a complete review of the patient's diet may be needed to avoid nutritional deficiencies.<ref name="titleOn Her Last Legs - New York Times">{{cite news |url=https://www.nytimes.com/2006/02/26/magazine/26wwln_diagnosis.html?_r=1&n=Top/News/Health/Diseases,%20Conditions,%20and%20Health%20Topics/Allergies&pagewanted=print&oref=slogin |title=On Her Last Legs - New York Times |accessdate=2008-01-25 |work=The New York Times | first1=Lisa | last1=Sanders | date=2006-02-26}}</ref> | |||
Various combinations of different antioxidants together with “detoxifying” measures that are not evidence based are recommended by some authors. “Treatment with a multitude of pills and infusions may lead to “catastrophizing”, thus making patients perceive their disorder particularly negatively; this phenomenon is known to have a negative impact on the subsequent disease course ... such treatments place a significant financial strain on patients.”<ref name="pmid32026633">{{cite journal |vauthors=Harter K, Hammel G, Fleming M, Traidl-Hoffmann C |title=Multiple chemical sensitivity (MCS) - a guide for dermatologists on how to manage affected individuals |journal=J Dtsch Dermatol Ges |volume=18 |issue=2 |pages=119–130 |date=February 2020 |pmid=32026633 |doi=10.1111/ddg.14027}}</ref> | |||
== Epidemiology == | == Epidemiology == | ||
Prevalence rates for MCS vary according to the diagnostic criteria used.<ref>"1.1.2 Studies on the prevalence of MCS in other countries." A Scientific Review of Multiple Chemical Sensitivity: Identifying Key Research Needs. Published in 2010 by the National Industrial Chemicals Notification and Assessment Scheme, Australian Government. Canberra. http://test.nicnas.gov.au/Media/Latest_News/MCS.asp {{Webarchive|url=https://web.archive.org/web/20200307155500/http://test.nicnas.gov.au/Media/Latest_News/MCS.asp |date=2020-03-07 }}</ref> 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.<ref name="Toronto" />{{Rp|37}} A 2018 study found that 6.5% of Australian adults reported having a medical diagnosis of MCS.<ref>Pigatto PD, Guzzi G. Prevalence and Risk Factors for MCS in Australia. ''Preventive Medicine Reports'' 2019.</ref><ref name=":21">{{Cite news |date=2 July 2018 |title=Common chemical products making Australians sick, study finds |url=https://about.unimelb.edu.au/newsroom/news/2018/july/common-chemical-products-making-australians-sick-study-finds |access-date=20 November 2019 |work=The University of Melbourne Newsroom}}</ref><ref name=":0">{{cite journal |author=Steinemann A |year=2018 |title=Prevalence and effects of multiple chemical sensitivities in Australia |journal=Prev Med Rep |volume=10 |pages=191–4 |doi=10.1016/j.pmedr.2018.03.007 |pmc=5984225 |pmid=29868366 |doi-access=free}}</ref> In Germany, 9% of adults say they have MCS, and 12% of adults in the US say they have been diagnosed.<ref name="Current 2021" /> When self-reports are included, about 20% of Australians and 25% of Americans say that they are more sensitive to chemicals than average.<ref name=":0" /><ref name="Current 2021" /> {{As of|2022}}, the number of people with MCS has either plateaued or is declining.<ref>{{Cite book |last1=Gardiner |first1=Kerry |url=https://onlinelibrary.wiley.com/doi/book/10.1002/9781119887638 |title=Pocket Consultant: Occupational Health |last2=Rees |first2=David |last3=Adisesh |first3=Anil |last4=Zalk |first4=David |last5=Harrington |first5=Malcolm |last6=Gervais |first6=Roxane |last7=Saary |first7=Joan |date=2022-03-25 |publisher=Wiley |isbn=978-1-119-71861-1 |edition=1 |language=en |doi=10.1002/9781119887638.ch18}}</ref> | |||
Epidemiological data from three states put the prevalence of chemical sensitivity in 1999 at 16% to 33% of the general population, 2% to 6% of whom have already been diagnosed with MCS.{{citation needed|date=June 2019}} Women complain of MCS significantly more often than men, and most patients are 30 to 50 years old at time of diagnosis.{{citation needed|date=June 2019}} | |||
] | |||
The condition is reported across industrialized countries.<ref name="Toronto" />{{Rp|37}} It affects significantly more women than men.<ref name="Current 2021" /> A typical age of onset is near ].<ref name="Current 2021" /> People with MCS are more likely to have high ] and to be well educated.<ref name="Current 2021" /> They are also more likely to have stressful work situations and a history of subjective health complaints.<ref name="Current 2021" /> | |||
For about half of people with MCS, the symptoms could be considered disabling.<ref name=":21" /><ref name=":0" /> | |||
===Gulf War syndrome=== | |||
Several clinical and epidemiological studies conducted in the United States and in the United Kingdom have investigated the occurrence of MCS in military personnel deployed to the Persian Gulf during the 1990s. Some of the health complaints and symptoms reported by veterans of the Gulf War attributed to ] are similar to those reported for MCS, including headache, fatigue, muscle stiffness, joint pain, inability to concentrate, sleep problems, and gastrointestinal issues.<ref>{{cite journal |vauthors=Gray GC, Gackstetter GD, Kang HK, Graham JT, Scott KC | year = 2004 | title = After more than 10 years of Gulf War Veteran medical evaluations, what have we learned? | url = | journal = American Journal of Preventive Medicine | volume = 26 | issue = 5| pages = 443–452 | doi=10.1016/j.amepre.2004.02.006| pmid = 15165662 }}</ref> | |||
===Related syndromes=== | |||
A population-based, cross-sectional epidemiological study involving American veterans of the Gulf War, non-Gulf War veterans, and non-deployed reservists enlisted both during Gulf War era and outside the Gulf War era concluded the prevalence of MCS-type symptoms in Gulf War veterans was somewhat higher than in non-Gulf War veterans.<ref name="pmid10789611">{{cite journal |vauthors=Black DW, Doebbeling BN, Voelker MD, Clarke WR, Woolson RF, Barrett DH, Schwartz DA |title=Multiple chemical sensitivity syndrome: symptom prevalence and risk factors in a military population |journal=Arch. Intern. Med. |volume=160 |issue=8 |pages=1169–76 |date=April 2000 |pmid=10789611 |doi= 10.1001/archinte.160.8.1169|url=}}</ref> After adjusting for potentially confounding factors (age, sex, and military training), there was a robust association between individuals with MCS-type symptoms and psychiatric treatment (either therapy or medication) before deployment and, therefore, before any possible deployment-connected chemical exposures.<ref name="pmid10789611"/> | |||
Symptoms attributed to ] are similar to those reported for MCS, including headache, fatigue, muscle stiffness, joint pain, inability to concentrate, sleep problems, and gastrointestinal issues.<ref name="Current 2021" /> Gulf War veterans are somewhat more likely to have symptoms consistent with MCS.<ref name="Current 2021" /> | |||
MCS is also similar to ], with both showing non-specific symptoms such as headaches, respiratory irritation and fatigue.<ref name="Current 2021" /> There is also some overlap in symptoms between MCS and ] (ME/CFS), though chemical exposures are not suspected in ME/CFS.<ref name="Current 2021" /> | |||
The odds of reporting MCS or chronic multiple-symptom illness was 3.5 times greater for Gulf War veterans than non-Gulf veterans.<ref>{{cite journal |vauthors=Thomas HV, Stimpson NJ, Weightman AL, Dunstan F, Lewis G | year = 2006 | title = Systematic review of multi-symptom conditions in Gulf War veterans." Multi-symptom illnesses, unexplained illness, and Gulf War Syndrome" | url =http://orca.cf.ac.uk/6803/1/Systematic_review.pdf | journal = Psychological Medicine | volume = 36 | issue = 6| pages = 735–747 | doi=10.1017/s0033291705006975| pmid = 16438740 }}</ref> | |||
== Prognosis == | |||
Gulf War veterans have an increased rate of multiple-symptom conditions compared to military personnel deployed to other conflicts, and although it is unexplained, Gulf War syndrome is not considered distinct from other medically unexplained syndromes observed in civilian populations, including MCS.<ref>{{cite journal |vauthors=Ismail K, Lewis G | year = 2006 | title = Multi-symptom illnesses, unexplained illness, and Gulf War Syndrome | url = | journal = Philosophical Transactions of the Royal Society B | volume = 361 | issue = 1468| pages = 543–551 | doi=10.1098/rstb.2006.1815| pmc = 1569616 | pmid=16687260}}</ref> | |||
About half of those with MCS get better over the course of several years, while about half continue to experience distressing or disabling symptoms.<ref name="Current 2021" /> | |||
== History == | == History == | ||
MCS was first proposed as a distinct disease by ] 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 |
MCS was first proposed as a distinct disease by ] in 1950. In 1965, Randolph founded the ] 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 ] emerged as a non-recognized medical specialty.<ref name="Current" /> | ||
Since the 1950s, many hypotheses have been advanced for the science surrounding multiple chemical sensitivity.<ref name=quebec-synth/> | |||
In 1994, the AMA, ], ] and US ] published a booklet on ] 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.<ref name="urlIndoor Air Pollution: An Introduction for Health Professionals | Publications | Indoor Air | Air | US EPA">{{cite book|title=Indoor Air Pollution: An Introduction for Health Professionals|year=1994|publisher= Co-sponsored by: The American Lung Association (ALA), The Environmental Protection Agency (EPA), The Consumer Product Safety Commission (CPSC), and The American Medical Association (AMA)|url=http://www.epa.gov/iedweb00/pubs/hpguide.html#faq1|quote=efinition of the phenomenon is elusive and its pathogenesis as a distinct entity is not confirmed....The current consensus is that in cases of claimed or suspected MCS, complaints should not be dismissed as psychogenic, and a thorough workup is essential. Primary care givers should determine that the individual does not have an underlying physiological problem and should consider the value of consultation with allergists and other specialists.|accessdate=2008-06-30}}</ref> | |||
In the 1990s, an association was noted with chronic fatigue syndrome, fibromyalgia, and Gulf War syndrome.<ref name="Donnay">{{cite journal|author=Donnay|first=Albert H|date=1999|title=On the Recognition of Multiple Chemical Sensitivity in Medical Literature and Government Policy|journal=International Journal of Toxicology|volume=18|issue=6|pages=383–392|doi=10.1080/109158199225099|s2cid=72141513}}</ref> | |||
In 1995, an Interagency Workgroup on Multiple Chemical Sensitivity was formed under the supervision of the Environmental Health Policy Committee within the ] to examine the body of research that had been conducted on MCS to that date. The work group included representatives from the ], ], ], ], and the ]. 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 ], 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.<ref>{{cite web|url=http://web.health.gov/environment/mcs/ |title=A Report on Multiple Chemical Sensitivity (MCS) |publisher=Web.health.gov |date=1998-08-24 |accessdate=2014-06-08}}</ref> | |||
In 1994, the AMA, ], ] and the US ] published a booklet on ] 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.<ref name="urlIndoor Air Pollution: An Introduction for Health Professionals | Publications | Indoor Air | Air | US EPA">{{cite book|title=Indoor Air Pollution: An Introduction for Health Professionals|year=1994|publisher= Co-sponsored by: The American Lung Association (ALA), The Environmental Protection Agency (EPA), The Consumer Product Safety Commission (CPSC), and The American Medical Association (AMA)|url=http://www.epa.gov/iedweb00/pubs/hpguide.html#faq1|quote=efinition of the phenomenon is elusive and its pathogenesis as a distinct entity is not confirmed....The current consensus is that in cases of claimed or suspected MCS, complaints should not be dismissed as psychogenic, and a thorough workup is essential. Primary care givers should determine that the individual does not have an underlying physiological problem and should consider the value of consultation with allergists and other specialists.|access-date=2008-06-30}}</ref> | |||
In 1997, U.S. ] Commissioner John Callahan issued a court memorandum officially recognizing MCS "as a medically determinable impairment" on an agency-wide basis.<ref>October 31, 1997, R-164, Creamer v. Callahan</ref> That is, without making any statement about the cause of MCS or the role of chemicals in MCS, the Social Security administration agrees that some MCS patients are too disabled to be meaningfully employed.<ref>{{cite web |url=https://secure.ssa.gov/apps10/poms.nsf/lnx/0424515064!opendocument |title=DI 24515.064 Evaluation Of Specific Issues — Environmental Illness|publisher=] |accessdate=8 May 2010 |quote=Therefore, in evaluating claims based on environmental illness, all of the claimant's symptoms, signs, and laboratory findings must be considered to determine if there is a medically determinable impairment and the impact of any impairment on the claimant's ability to work. This evaluation should be made on an individual case-by-case basis to determine if the impairment prevents substantial gainful activity.}}</ref> | |||
In 1995, an Interagency Workgroup on Multiple Chemical Sensitivity was formed under the supervision of the Environmental Health Policy Committee within the ] to examine the body of research that had been conducted on MCS to that date. The work group included representatives from the ], ], ], ], and the ]. 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 ], 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.<ref>{{citation|last=Interagency Workgroup on Multiple Chemical Sensitivity|title=A Report on Multiple Chemical Sensitivity (MCS)|date=1998-08-24|url=http://web.health.gov/environment/mcs/|archive-url=https://web.archive.org/web/20140718033446/http://www.health.gov/environment/mcs/toc.htm|publisher=Web.health.gov|access-date=2014-06-08|archive-date=2014-07-18|url-status=dead}}</ref> | |||
A 1997 U.S. court decision held that MCS "is untested, speculative, and far from generally accepted in the medical or toxicological community," and thus cannot be used as the basis for disability claims.<ref>''Frank v. New York'', 972 F. Supp. 130 (N.D.N.Y. 1997)</ref> Furthermore, accommodations sought for MCS are sometimes denied as being unreasonable as a matter of law.<ref>Andrew K. Kelley, "COMMENT: Sensitivity Training: Multiple Chemical Sensitivity and the ADA," 25 B.C. Envtl. Aff. L. Rev. 485; see, for example, ''Whillock v. Delta Air Lines'', 926 F.Supp. 1555 (N.D.Ga. 1995) http://lawdigitalcommons.bc.edu/ealr/vol25/iss2/5/</ref> | |||
The different understandings of MCS over the years have also resulted in different proposals for names.<ref name=":1" /> For example, in 1996 the International Programme on Chemical Safety proposed calling it ''idiopathic environmental illness'', because of their belief that chemical exposure may not the sole cause,<ref name="International Programme" /> while another researcher, whose definition includes people with allergies and acute poisoning, calls it ''chemical sensitivity''.<ref name=":1" /> | |||
In July 2017, the Task Force on ] of the Ontario, Canada ] issued a Phase 1 report, "Time for Leadership: Recognizing and Improving Care for those with ME/CFS, FM and ES/MCS",<ref>http://www.health.gov.on.ca/en/common/ministry/publications/reports/environmental_health_2017 /task_force_on_environmental_health_report.pdf</ref> summarized in '']'' in June 2018.<ref>{{Cite journal|pmc = 5999262|year = 2018|last1 = Hu|first1 = H|title = Recent insights into 3 underrecognized conditions: Myalgic encephalomyelitis–chronic fatigue syndrome, fibromyalgia, and environmental sensitivities–multiple chemical sensitivity|journal = Canadian Family Physician|volume = 64|issue = 6|pages = 413–415|last2 = Baines|first2 = C|pmid = 29898928}}</ref> In February 2018, the '']'' published "Multiple Chemical Sensitivity: Review of the State of the Art in Epidemiology, Diagnosis, and Future Perspectives" covering 17 years of literature internationally on the topic.<ref>{{Cite journal|pmc = 5794238|year = 2017|last1 = Rossi|first1 = S|title = Multiple Chemical Sensitivity: Review of the State of the Art in Epidemiology, Diagnosis, and Future Perspectives|journal = Journal of Occupational and Environmental Medicine|volume = 60|issue = 2|pages = 138–146|last2 = Pitidis|first2 = A|pmid = 29111991|doi = 10.1097/JOM.0000000000001215}}</ref> | |||
== |
== 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).<ref name="Hsu">{{Citation |last=Hsu |first=Hsuan L. |title="Every Crime Has Its Peculiar Odor": Detection, Deodorization, and Intoxication |date=2020-12-31 |work=The Smell of Risk |pages=27–55 |url=https://www.degruyter.com/document/doi/10.18574/nyu/9781479807215.003.0002/html |publisher=New York University Press |doi=10.18574/nyu/9781479807215.003.0002 |isbn=978-1-4798-0537-2 |via=]}}</ref><ref name="Alaimo">{{Cite book |last=Alaimo |first=Stacy |title=Bodily Natures: Science, Environment, and the Material Self |publisher=] |year=2010 |isbn=978-0-253-22240-4 |location=Bloomington (Ind.) |chapter=Deviant Agents: The Science, Culture, and Politics of Multiple Chemical Sensitivity}}</ref> 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.<ref name="Hsu" /> | |||
In Todd Haynes' "]", Carol White (played by ]) seeks treatment for many unrelated symptoms (such as coughing fits after breathing exhaust fumes, convulsions after consuming dairy), eventually being convinced that she suffers from multiple chemical sensitivity. | |||
Multiple chemical sensitivity has been featured in the film such as ], a 1995 fictional ] film.<ref name="Alaimo" /><ref>{{Citation |first1=Stephen |last1=Tapert |title=Julianne Moore |date=2022-12-31 |work=Best Actress |pages=451–454 |url=https://www.degruyter.com/document/doi/10.36019/9781978809598-075/html |access-date=2024-05-15 |publisher=Rutgers University Press |doi=10.36019/9781978809598-075 |isbn=978-1-9788-0959-8}}</ref> | |||
In Canada, Multiple Chemical Sensitivity afflicted the fictional character Mike Monroe in the 90's drama ]. | |||
=== International Statistical Classification of Diseases === | |||
The ] (ICD), maintained by the ], is a ] system used for ] 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, <span lang="de" dir="ltr">Unerwünschte Nebenwirkungen, anderenorts nicht klassifiziert</span> ("adverse reactions, not otherwise specified").<ref name="Harter">{{Cite journal |last1=Harter |first1=Katharina |last2=Hammel |first2=Gertrud |last3=Fleming |first3=Megan |last4=Traidl-Hoffmann |first4=Claudia |date=February 2020 |title=Multiple chemical sensitivity (MCS) – a guide for dermatologists on how to manage affected individuals |journal=JDDG: Journal der Deutschen Dermatologischen Gesellschaft |language=en |volume=18 |issue=2 |pages=119–130 |doi=10.1111/ddg.14027 |issn=1610-0379 |pmid=32026633 |doi-access=free}}</ref> 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 ] ("S3") ] for the management of patients with nonspecific, functional symptoms.<ref name="Harter" /> | |||
==See also== | ==See also== | ||
* ] | * ] | ||
* ] | |||
* ] | |||
* ] | * ] | ||
* ] | * ] | ||
* ] | |||
* ] | |||
* ] | |||
* ] | |||
* ] | |||
* ] | |||
== References == | == References == | ||
{{ |
{{reflist}} | ||
== Further reading == | |||
*{{cite journal |vauthors=Molot J, Sears M, Marshall LM, Bray RI |title=Neurological susceptibility to environmental exposures: pathophysiological mechanisms in neurodegeneration and multiple chemical sensitivity |journal=Rev Environ Health |volume=37 |issue=4 |pages=509–530 |date=December 2022 |pmid=34529912 |doi=10.1515/reveh-2021-0043 |type=review}} | |||
*{{cite journal |vauthors=Palmieri B, Corazzari V, Vadala' M, Vallelunga A, Morales-Medina JC, Iannitti T |title=The role of sensory and olfactory pathways in multiple chemical sensitivity |journal=Rev Environ Health |volume=36 |issue=3 |pages=319–326 |date=September 2021 |pmid=33070122 |doi=10.1515/reveh-2020-0058 |doi-access=free }} | |||
== External links == | == External links == | ||
* at the ] Professional Edition | * at the ] Professional Edition | ||
{{Medicine}} | |||
{{Authority control}} | {{Authority control}} | ||
{{DEFAULTSORT:Multiple chemical sensitivity}} | |||
] | ] | ||
] | |||
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Latest revision as of 04:05, 29 December 2024
Controversial medical diagnosis
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Multiple chemical sensitivity (MCS) is an underrecognized diagnosis characterized by chronic symptoms attributed to exposure to low levels of commonly used chemicals. Symptoms are typically vague and non-specific. They may include fatigue, headaches, nausea, respiratory problems, seizures, confusion, lethargy, pain, and dizziness.
Recent imaging studies have shown that it is likely a neurological condition.
MCS is a chronic disease that requires ongoing management. In the long term, about half of people with MCS get better and about half continue to be affected, sometimes severely.
Classification
In nosological terms, MCS may be more than one disease.
It is generally considered a subtype of non-allergic chemical intolerance (also called chemical sensitivity).
MCS is considered an acquired disorder, meaning that it was not present from birth but instead developed later.
Compared to other conditions with medically unexplained physical symptoms, such as Myalgic encephalomyelitis/chronic fatigue syndrome, fibromyalgia or Gulf War syndrome, MCS symptoms are only present in response to environmental triggers.
Name
The name multiple chemical sensitivity has been criticized, partly because MCS is not a sensitivity in the allergic or immunological meaning of that word. Being more sensitive than average to some chemical exposures (e.g., secondhand smoke) is fairly common. MCS is generally used to refer to more significant disability.
The name has also been criticized because it suggests that chemical exposure is the actual cause or etiology, which has not been proven. The word chemical in the name is used loosely and includes natural substances (e.g., the aromas produced by pine trees or other fragrant plants). Other names, such as idiopathic environmental intolerance, have been recommended as more accurate alternatives.
Definitions
Different researchers and proponents use different definitions, which complicates research and can affect diagnosis. 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.
In Japan, MCS is called chemical hypersensitivity or chemical intolerance (化学物質過敏症; kagaku bushitsu kabinsho), and the 1999 Japanese definition requires one or more of four major symptoms – headaches; malaise and fatigue; muscle pain; joint pain – combined with laboratory findings and/or some minor symptoms, such as mental effects or skin conditions. 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.
Another definition requires a known precipitating event (e.g., an injury or an illness) followed by the appearance of multi-organ symptoms that predictably wax and wane in response to a variety of exposures that do not bother other people. 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). Other people have symptoms affecting the eyes, ears, and nose (e.g., stuffy nose), the respiratory system (e.g., shortness of breath), gastrointestinal system (e.g., nausea), musculoskeletal system (e.g., joint pain), or dermatological system (e.g., itching).
A 2010 review of MCS literature said that the following symptoms, in this order, were the most reported in the condition: headache, fatigue, confusion, depression, shortness of breath, arthralgia, myalgia, nausea, dizziness, memory problems, gastrointestinal symptoms, respiratory symptoms.
Symptoms mainly arise from the autonomic nervous system (such as nausea or dizziness) or have psychiatric or psychological aspects (such as difficulty concentrating).
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."
The US Occupational Safety and Health Administration (OSHA) says that MCS is highly controversial and that there is insufficient scientific evidence to explain the relationship between any of the suggested causes of MCS – it lists "allergy, dysfunction of the immune system, neurobiological sensitization, and various psychological theories" as the suggested causes – and its symptoms.
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.
Genetic
It has been hypothesized that there is a heritable genetic trait which pre-disposes people to be hypersensitive to low-level chemical exposure and so develop MCS. To investigate, researchers compared the genetic makeup of people with MCS, to people without. The results were generally inconclusive and contradictory, thus failing to support the hypothesis.
Gaétan Carrier and colleagues write that the genetic hypothesis appears implausible when the evidence around it is judged by the Bradford Hill criteria.
Psychological
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This section needs more reliable medical references for verification or relies too heavily on primary sources. Please review the contents of the section and add the appropriate references if you can. Unsourced or poorly sourced material may be challenged and removed. Find sources: "Multiple chemical sensitivity" – news · newspapers · books · scholar · JSTOR (November 2021) |
Many people with MCS also include , migraine, chronic fatigue syndrome, or fibromyalgia and brain fog. Via toxic exposures, it has been proven that people with MCS may develop real symptoms, such as nausea and headache, when they encounter certain odors or other toxic chemical triggers. From 2011-2016 Multiple Chemical Sensitivity was illegally added to the USA ICD10 medical diagnostic code system. The CDC ICD10 code maintenance supervisor said they have no idea how it got into the system. It was removed in 2011. (Source CDC and https://icd.codes/icd10cm/F459# MCS is often a nerve agent injury symptom of Gulf War Illness and Other War Theaters which was added to CDC ICD10 in 2024.
A 2018 systematic review concluded that the evidence suggests that abnormalities in sensory processing pathways combined with peculiar personality traits best explains this condition.
Diagnosis
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In practice, diagnosis relies upon the self-reported claim that the symptoms are triggered by exposure to various substances. In 1999, Dr. Claudia Miller and Dr. Thomas Prihoda of the University of Texas Health Science Centre in San Antonio developed the Quick Environmental Exposure and Sensitivity Inventory (QEESI) questionnaire to help physicians standardize such reported symptoms.
Commonly attributed substances include scented products (e.g. perfumes, air fresheners and laundry products), 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.
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 and no scientific consensus on supportive therapies. The literature generally agrees on the need for MCS patients to avoid the specific substances that trigger reactions for them as well as xenobiotics in general, in order to prevent further sensitization. The goal of treatment is to improve quality of life, with fewer distressing symptoms and the ability to maintain employment and social relationships, rather than to produce a permanent cure.
Some literature recommends a multidisciplinary treatment approach that takes into account the uncommon personality traits often seen in affected individuals and physiological abnormalities in sensory pathways and the limbic system.
Common self-care strategies include avoiding exposure to known triggers and emotional self-care. Healthcare providers can provide useful education on the body's natural ability to eliminate and excrete toxins on its own and support positive self-care efforts. Avoiding triggers, such as by removing smelly cleaning products from the home, can reduce symptoms and increase the person's sense of being able to reclaim a reasonably normal life. However, for other people with MCS, their efforts to avoid suspected triggers will backfire, and instead produce harmful emotional side effects that interfere with the overall goal of reducing distress and disability. Treatments that have not been scientifically validated, such as "elimination or rotary diversified diets", hormone supplement and chemical detoxification through exercise have been used by people with MCS. "Controversial treatment methods offer hope of improvement to many individuals with MCS." Unproven treatments can be expensive, may cause side effects, and may be counterproductive.
Various combinations of different antioxidants together with “detoxifying” measures that are not evidence based are recommended by some authors. “Treatment with a multitude of pills and infusions may lead to “catastrophizing”, thus making patients perceive their disorder particularly negatively; this phenomenon is known to have a negative impact on the subsequent disease course ... such treatments place a significant financial strain on patients.”
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. A 2018 study found that 6.5% of Australian adults reported having a medical diagnosis of MCS. In Germany, 9% of adults say they have MCS, and 12% of adults in the US say they have been diagnosed. When self-reports are included, about 20% of Australians and 25% of Americans say that they are more sensitive to chemicals than average. As of 2022, the number of people with MCS has either plateaued or is declining.
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.
Since the 1950s, many hypotheses have been advanced for the science surrounding multiple chemical sensitivity.
In the 1990s, an association was noted with chronic fatigue syndrome, fibromyalgia, and Gulf War syndrome.
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. For example, in 1996 the International Programme on Chemical Safety proposed calling it idiopathic environmental illness, because of their belief that chemical exposure may not the sole cause, 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.
Multiple chemical sensitivity has been featured in the film such as Safe, a 1995 fictional psychological horror film.
In Canada, Multiple Chemical Sensitivity afflicted the fictional character Mike Monroe in the 90's drama North of 60.
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
- Hyperosmia
- Electromagnetic hypersensitivity
- Sick building syndrome
- Sensory processing disorder
- Sensory processing sensitivity
- List of questionable diseases
- Environmental health
- Environmental medicine
- Indoor air quality
- Sense of smell#Disorders
- Mast Cell Activation Syndrome
References
- ^ Genuis SJ (May 2013). "Chemical sensitivity: pathophysiology or pathopsychology?". Clinical Therapeutics. 35 (5): 572–7. doi:10.1016/j.clinthera.2013.04.003. PMID 23642291.
- ^ Templeton DM, Schwenk M, Duffus JH (2016), "Multiple Chemical Sensitivity (MCS)", IUPAC Glossary of Terms Used in Neurotoxicology, De Gruyter, doi:10.1515/pac-2015-0103,
multiple chemical sensitivity (MCS) -environmental illness -idiopathic environmental intolerance -Intolerance condition attributed to extreme sensitivity of individuals to various environmental chemicals, found in air, food, water, building materials, or fabrics. Note 1: This syndrome is characterized by the patient's belief that his or her symptoms are caused by very low-level exposure to environmental chemicals. The term "chemical" is used to refer broadly to many natural and man-made substances, some of which have several chemical constituents. Note 2: ...
- Molot J, Sears M, Anisman H (2023-08-01). "Multiple chemical sensitivity: It's time to catch up to the science". Neuroscience & Biobehavioral Reviews. 151: 105227. doi:10.1016/j.neubiorev.2023.105227. ISSN 0149-7634. PMID 37172924.
- ^ Harrison RJ (2021). "Multiple Chemical Sensitivity". Current Occupational & Environmental Medicine (Sixth ed.). New York: McGraw-Hill Education/Medical. pp. 853–860. ISBN 978-1260143430. OCLC 1250024967.
- ^ Linde B, Redlich CA (10 February 2021). "Symptomatic Responses to Low-Level Occupational and Environmental Exposures". In Harris R (ed.). Patty's Industrial Hygiene (7th ed.). Wiley. doi:10.1002/0471435139.hyg013.pub3. ISBN 978-0-471-29784-0.
- Linde B, Redlich CA (10 February 2021). "Symptomatic Responses to Low-Level Occupational and Environmental Exposures". In Harris R (ed.). Patty's Industrial Hygiene (7th ed.). Wiley. doi:10.1002/0471435139.hyg013.pub3. ISBN 978-0-471-29784-0.
- ^ International Programme on Chemical Sensitivity (February 1996). "Report of Multiple Chemical Sensitivities Workshop" (PDF). Berlin, Germany. Retrieved 11 June 2020.
- ^ Rossi S, Pitidis A (February 2018). "Multiple Chemical Sensitivity: Review of the State of the Art in Epidemiology, Diagnosis, and Future Perspectives". Journal of Occupational and Environmental Medicine. 60 (2): 138–146. doi:10.1097/JOM.0000000000001215. ISSN 1076-2752. PMC 5794238. PMID 29111991.
- ^ Katoh T (2018). "Multiple Chemical Sensitivity (MCS): History, Epidemiology and Mechanism" [Multiple Chemical Sensitivity (MCS): History, Epidemiology and Mechanism]. Nihon Eiseigaku Zasshi (Japanese Journal of Hygiene) (in Japanese). 73 (1): 1–8. doi:10.1265/jjh.73.1. ISSN 1882-6482. PMID 29386440.
- ^ Schwenk M (2004). "Multiple Chemical Sensitivity (MCS) - Scientific and Public-Health Aspects". GMS Current Topics in Otorhinolaryngology, Head and Neck Surgery. 3: Doc05. ISSN 1865-1011. PMC 3199799. PMID 22073047.
- "Safety and Health Topics: Multiple Chemical Sensitivities". Occupational Safety and Health Administration. Retrieved 2021-01-06.
- ^ A Scientific Review of Multiple Chemical Sensitivity: Identifying Key Research Needs, Canberra, Australia: National Industrial Chemicals Notification and Assessment Scheme, Australian Government, 2010, archived from the original on 2020-03-07
- Katoh T (2018). "Multiple Chemical Sensitivity (MCS): History, Epidemiology and Mechanism". Nihon Eiseigaku Zasshi [Japanese Journal of Hygiene] (in Japanese). 73 (1): 1–8. doi:10.1265/jjh.73.1. ISSN 1882-6482. PMID 29386440.
- ^ Carrier G, Tremblay M, Allard R (June 2021). Syndrome de sensibilité chimique multiple, une approche intégrative pour identifier les mécanismes physiopathologiques (PDF) (Synthèse) (in Canadian French). Institut national de santé publique du Québec. ISBN 978-2-550-88675-4.
- ^ "Time for Leadership: Recognizing and Improving Care for Those with ME/CFS, FM and ES/MCS" (PDF), Task Force on Environmental Health, Toronto, Ontario: Ministry of Health and Long-Term Care, 2017
- ^ "Time for leadership: recognizing and improving care for those with ME/CFS, FM and ES/MCS" (PDF), Task Force on Environmental Health, Toronto, Ontario: Ministry of Health and Long-Term Care, p. 53, 2017
- "Safety and Health Topics | Multiple Chemical Sensitivities". Osha.gov. Retrieved 2014-06-08.
- ^ Viziano A, Micarelli A, Pasquantonio G, Della-Morte D, Alessandrini M (November 2018). "Perspectives on multisensory perception disruption in idiopathic environmental intolerance: a systematic review". Int Arch Occup Environ Health. 91 (8): 923–935. Bibcode:2018IAOEH..91..923V. doi:10.1007/s00420-018-1346-z. PMID 30088144. S2CID 51936485.
- ^ Harrison R (2014). "Multiple Chemical Sensitivity". Current Occupational & Environmental Medicine (Fifth ed.). New York: McGraw-Hill Education/Medical. pp. 819–826. ISBN 978-0-07-180816-3. OCLC 898477589.
controversial methods have been used ... including elimination or rotary diversified diets, vitamins or nutritional supplements, oxygen, antifungal and antiviral agents, thyroid hormone supplement, supplemental estrogen or testosterone, transfer factor, chemical detoxification through exercise and sauna treatment, intravenous gamma-globulin, and intracutaneous or subcutaneous neutralization. A specially designed chemical-free environmental control unit has been used as a method to decrease blood pesticide levels and ... Controversial treatment methods offer hope of improvement to many individuals with MCS, and some patients do report symptom improvement over time. Many ... are expensive and rarely are covered by health insurance. These treatment methods have not been validated through carefully designed, controlled trials, may have unwanted side effects ... page 826
- Miller and Prihoda Ca (March 1999). "The Environmental Exposure and Sensitivity Inventory (EESI): a standardized approach for measuring chemical intolerances for research and clinical applications". ResearchGate, Toxicology and Industrial Health.
- "Chemical Intolerance Self Assessment". Hoffman Program for Chemical Intolerance. Retrieved 2024-12-29.
- Harter K, Hammel G, Fleming M, Traidl-Hoffmann C (February 2020). "Multiple chemical sensitivity (MCS) - a guide for dermatologists on how to manage affected individuals". J Dtsch Dermatol Ges. 18 (2): 119–130. doi:10.1111/ddg.14027. PMID 32026633.
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efinition of the phenomenon is elusive and its pathogenesis as a distinct entity is not confirmed....The current consensus is that in cases of claimed or suspected MCS, complaints should not be dismissed as psychogenic, and a thorough workup is essential. Primary care givers should determine that the individual does not have an underlying physiological problem and should consider the value of consultation with allergists and other specialists.
- Interagency Workgroup on Multiple Chemical Sensitivity (1998-08-24), A Report on Multiple Chemical Sensitivity (MCS), Web.health.gov, archived from the original on 2014-07-18, retrieved 2014-06-08
- ^ Hsu HL (2020-12-31), ""Every Crime Has Its Peculiar Odor": Detection, Deodorization, and Intoxication", The Smell of Risk, New York University Press, pp. 27–55, doi:10.18574/nyu/9781479807215.003.0002, ISBN 978-1-4798-0537-2 – via De Gruyter
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- ^ Harter K, Hammel G, Fleming M, Traidl-Hoffmann C (February 2020). "Multiple chemical sensitivity (MCS) – a guide for dermatologists on how to manage affected individuals". JDDG: Journal der Deutschen Dermatologischen Gesellschaft. 18 (2): 119–130. doi:10.1111/ddg.14027. ISSN 1610-0379. PMID 32026633.
Further reading
- Molot J, Sears M, Marshall LM, Bray RI (December 2022). "Neurological susceptibility to environmental exposures: pathophysiological mechanisms in neurodegeneration and multiple chemical sensitivity". Rev Environ Health (review). 37 (4): 509–530. doi:10.1515/reveh-2021-0043. PMID 34529912.
- Palmieri B, Corazzari V, Vadala' M, Vallelunga A, Morales-Medina JC, Iannitti T (September 2021). "The role of sensory and olfactory pathways in multiple chemical sensitivity". Rev Environ Health. 36 (3): 319–326. doi:10.1515/reveh-2020-0058. PMID 33070122.
External links
- Multiple Chemical Sensitivity Syndrome at the Merck Manual Professional Edition