Article: Multiple chemical sensitivity

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


Mark R. Cullen [1], et al, of Yale Environmental Medicine have published a definition of MCS, making diagnosis possible. Yale Environmental Health provides a comprehensive evaluation, considering differential diagnosis as well Yale Environmental Health Clinical Services.

MCS etiology is hotly debated among physicians: some believe that MCS is the result of increase in exposure to irritants or a toxic injury, some believe that MCS is a physical illness with a yet-to-be-determined mechanism, and some believe that MCS is psychosomatic. Despite this debate, there is consensus that patients who complain of symptoms should avoid chemical irritants as best as possible. Respect in care and recommendation of avoidance of irritants is now standard protocol recommended by the American Medical Association. [2]

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

Some people with MCS say that they were injured by a single exposure to chemicals. Others say that they developed an intolerance to chemicals over time. Others are uncertain as to how their intolerance to chemicals developed. However, all agree that exposure to chemical irritants precipitates sometimes disabling symptoms such as migraine headache, sinus congestion, itchy eyes and throat, nausea and vomiting, indigestion, irritable bowel, constipation, bloating, rashes, asthma, muscle aches, joint aches, fatigue, flu like symptoms, depression, irritability, anxiety, mania, inability to concentrate, stupor, sleepiness, insomnia.

Conventional medicine does not typically recognize the MCS diagnosis, because to date there is no definitive test for diagnosis or proven scientific mechanism. Symptoms may be explainable by allergic, metabolic, enzymatic, inflammatory,infectious, or psychological mechanism. Because the nature and cause(s) of MCS are still unanswered, conventional medical testing for legal purposes is not yet available.

Unknown chemicals in the testing environment may confuse researchc results. In one blinded test, patients appeared to show no reaction to suspected substances. The same patients also seemed to react to saline solution injections and purified air injected into their environment. Chemical contamination of the testing environment may have affected results.

Allergist Theron G. Randolph (1906-1995) coined the term “multiple chemical sensitivities.” He observed in his clinical patients that exposure to low levels to modern synthetic chemicals caused a wide range of symptoms. His observations challenged the toxicology maxim that there must be a correlation between level chemical dose and the level of symptom effect.

Randolph theorized that the human body is like a barrel filling up with chemicals until it is full. Any further exposure to chemicals causes allergic reactions, like the straw that broke the camel's back.

Science recognizes that there are chemicals that build up in the body (such as mercury), but these are not yet recognized to cause allergic reactions. However, some people claim that after a meal of fish, they have an immediate bout of diarrhea. This may be another chemical sensitivity reaction.

Chemicals such as mercury can also cause organ failure, such as failure of the liver (which is involved in storing these chemicals) or the kidneys (involved in filtering them out). Some chemicals are also stored in body fat. These effects have never been found in MCS patients, either suggesting that they actually do not suffer from the effects of chemicals or that there is another mechanism (possibly the one Randolph proposed) to blame for their symptoms.

Medical doctors who treat MCS are called "clinical ecologists", and many belong to the American Academy of Environmental Medicine, which Randolph founded in 1965 as the Society for Clinical Ecology. Clinical Ecology is not recognized by the American Medical Association.

An alternative sensitization mechanism has been proposed by H.R. Eriksen and H. Ursin in a paper publicized April 2004. They propose the term 'subjective health complaints' for MCS and a number of other conditions that are similarly “vague”, such as epidemic fatigue, chronic musculoskeletal pain, chronic low back pain, chronic fatigue syndrome, and fibromyalgia. According to them: 'These complaints are particularly common in individuals with low coping and high levels of helplessness and hopelessness'. They suggest that: 'These complaints are based on sensations from what in most people are normal physiological processes. In some individuals these sensations become intolerable. In some cases it may signal somatic disease, in most cases not'. In their conclusion they suggest that the psychobiological mechanisms for this is sensitization in neural loops maintained by sustained attention and arousal. This Erikson-Ursin “suggestion” is unproven.

It may be that chemical sensitivities and exposure cause low coping mechanisms rather than that low coping mechanisms cause chemical sensitivities. One MCS patient had the mercury filling removed from her mouth, became outgoing, got a good job, and reversed a lifetime pattern of “low coping.”

For practical purposes, according to a patient survey by Alison Johnson, the most reliable way to achieve relief from symptoms and to create long term improvement in health is to avoid the offending chemicals.

People diagnosed with MCS suffer widely assorted symptoms blamed on exposure to trace levels of environmental chemicals. In one person, formaldehyde may cause arthritis, in another insomnia, in another sore throat. In one person, insomnia may be caused by phenols, in another by MSG, in another by sulfites. This lack of correltation between symptom and chemical trigger makes research difficult.


Common symptoms of MCS

  • anaphylactic shock
  • difficulty breathing, chest pains and asthma
  • skin irritation, contact dermatitis, and hives or other forms of skin rash
  • migraine headaches
  • "brain fog" (short term memory loss, cognitive dysfunction, including attention deficit)
  • digestive difficulties, nausea, indigestion/heartburn, vomiting, diarrhea
  • food intolerances, which may or may not be clinically identifiable (e.g., lactose intolerance, celiac disease). Commonly wheat and dairy.
  • joint and muscle pains
  • extreme fatigue, lethargy and lassitude
  • vertigo/dizziness
  • abnormally acute sense of smell (which may simply be the result of ridding one's home of strong masking scents, therefore purging olfactory neurons)
  • sensitivity to natural plant fragrance, pine turpines
  • insomnia
  • dry mouth, dry eyes
  • overactive bladder

Biological and chemical toxic injuries cause many systemic disturbances, especially within the functioning of the immune and central nervous systems. Although depression can occur as a consequence of a toxic injury, depression and other psychological illnesses do not cause toxic injuries. Unfortunately, the preponderance of physicians are not trained to properly diagnose or treat the chronic effects of toxic injuries and, in their ignorance, are quick to blame the patient, often misdiagnosed MCS patients as suffering from depression, anxiety and other psychological problems. This has mislead some pro-chemical and pro-pharmaceutical experts to erroneously posit that MCS is a physical manifestation of psychological disturbance (a psychosomatic illness) which should be treated with psychotherapy and anti-depressants, where, in fact, most chemically-injured people suffer no depression whatsoever.

Irritable Bowel Syndrome provides an example of an illness with no definitive diagnostic test that is often mistakenly seen as psychological. It is now known that when IBS patients are put on a special diet and improve, many of their "neurotic" symptoms clear.(Brostoff J. Irritable Bowel Syndrome. N Engl J Med 1994)

People can get anxious or depressed because of their illness, or their anxiety or depression can be the underlying cause. The use of anti-depressants [specifically, SSRIs] with a number of patients has shown dramatic, albeit temporary, improvement, as it further increases the body's toxic load and temporarily masks symptoms.

Treatments offered by practitioners of environmental medicine specify avoidance of known allergens and irritants, nutritional support to open up the body's various detoxification channels designed to purge the body of its toxic load, sauna detoxification, autolymphycyte factor treatment, allergy shots, experimental treatments and several other temporary and sometimes permanent lifestyle changes that can have a severe impact on peoples lives.

Enclosed air-conditioned buildings with a recycled air supply such as shopping centres, malls or large office buildings are deemed particularly bad environments for the chemically-sensitive. Patients avoid certain types of fabric for their clothing, hang printed paper outside for days (or avoid it all together), use only untreated wooden furniture, take only organic food etc. Some avoid contact with the outside world all together.

Commonly suspect chemicals

  • bleach, fabric softeners, wool-wash, and detergents
  • perfumes, air-fresheners and anything scented or perfumed
  • petrol or gasoline, diesel and exhaust fumes
  • pesticides, fertilisers, and other agricultural chemicals
  • shampoos, hairsprays and personal care products
  • dishwashing liquid and detergent (may cause migraine headaches for those without MCS)
  • most glues (including carpet glue), varnishes, polishes, paints, solvents and paint-thinners
  • petroleum-based products (including petroleum jelly)
  • Formaldyhyde and aldehyde

In particular, offgassing chemicals (some odorless, some not) are suspect.

Solvents are suspect, because there is no debate in medical science that these can cause permanent brain damage after long exposure. The associated illness is popularly known as painters' syndrome, since (professional) painters are exposed to paint-thinner fumes on a daily basis for many years. For this reason, many countries have banned thinner-based paints and replaced them with water-based paints. There is however no evidence thinner causes damage to people only occasionally exposed to them. Non VOC, healthier paints may be obtained.

One hypothesis is that buildup of trace levels of chemicals is the cause of MCS. This would seem to make almost any substance suspect, since every substance is fatal if the dose is high enough. However, some chemicals have a greater tendency to accumulate in the body than others.

Another hypothesis is that the chemicals triggers a coagulation response (which is also seen in [30% of allergic reactions) and that this is a non-IgE allergy response. In the case of MCS, there appears to be a genetic or acquire coagulation defect (for example Prothrombin 20210) resulting in a slow clearing of the coagulation products with the consequence of hypoxia symptoms and is some individuals, poor clearing of toxins from the body. Many individuals with MCS have triggers that are documented to be coagulation triggers:

  • Temperature
  • Electrical fields
  • Airline flights especially those longer than 2 hours
  • Fluorides and Fluoridation
  • Mercury
  • Exercise
  • Stress and Adrenaline
  • Fluorescent lighting (see with those with [Lupus] antibodies).

Many people with MCS also avoid exposure to inks, laser printers, and other potentially offgassing substances such as new furniture and plastic items.

MCS patients do not all agree about the possible etiology of the symptoms. While many believe that chemical or mold exposure is central to the etiology of MCS, others believe that their symptoms, including sensitivity to smell, are a part of a larger picture such as severe migraine with aura or depression -- both of which involve neurotransmitters.

MCS has been reported to be reduced significantly with 4000 IU of Vitamin D3 daily over 6+ months. It has been suggested that a Vitamin D deficiency is a significant contributor to many auto-immune illnesses (as it is with multiple sclerosis).

See also Gulf War syndrome

Further reading

  • Theron G. Randolph, M.D., and Ralph W. Moss, Ph.D (1990). An Alternative Approach to Allergies: Revised Edition ISBN 0060916931
  • Peter Radetsky (1997). Allergic to the Twentieth Century ISBN 0316732214
  • Nicholas Ashford and Claudia Miller (1998). Chemical Exposures:Low Levels and High Stakes. Second Edition. ISBN 0471292400
  • Bonnye L. Matthews, Ed. (1998). Defining Multiple Chemical Sensitivity. McFarland & Company. ISBN 0786404132
  • Sherry Rogers (1998). Chemical Sensitivity. McGraw-Hill. ISBN 0879836342


Author and motivational icon, Season BubbleGirl, has gone far into making the public aware of Multiple Chemical Sensitivity, relaying life with MCS in her autobiography, Absolute Individual: Life in a Bubble, her website, www.bubblegirl.net, and through press releases and articles worldwide.

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