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.

Cullen, et al, of Yale Environmental Medicine has published a definition of MCS, making diagnosis possible. However, etiology is hotly debated. MCS is a non-standard medical diagnosis in the US for people with unexplained allergy-like symptoms. Conventional medicine does not typically recognize this diagnosis [Yale Environmental Medicine, among others, provides diagnosis of MCS], because to date there is no definitive test for diagnosis or proven scientific mechanism. Symptoms may be explainable by other means such as more conventional allergies, infectious disease, or psychological reaction to stress.

There is argument [1] ( that MCS is a purely psychosomatic disease. In tests of dozens of people who where diagnosed (by alternative health practitioners) as having MCS, none of them showed any reaction to suspected substances when exposed to them without their knowledge, though they did show allergic reactions when they knew they were being exposed. They also showed allergic reactions to injections of (biologically inert) saline solution or exposure to purified air when they were falsely told they were being exposed to suspect substances. In short, there was no correlation between actual exposure and reaction, only between perceived exposure and reaction.

It should be noted that illnesses such as asthma and (normal) allergies were also once considered to be psychosomatic.

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

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.

People diagnosed with MCS suffer widely assorted symptoms blamed on exposure to trace levels of environmental chemicals. No two MCS patients will experience exactly the same symptoms.


Common symptoms of MCS

MCS patients often suffer from depression, anxiety and other psychological problems, leading some experts to believe that MCS is a physical manifestation of psychological disturbance (a psychosomatic illness) which should be treated with psychotherapy and anti-depressants. It is however difficult to judge cause and effect. Irritable Bowel Syndrome provides an example of an illness 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 improvement, with disappearance of MCS symptoms, though it would be non-sequitur reasoning to conclude that this will work for all patients.

Treatments, offered by practitioners of alternative medicine, usually revolve around avoiding exposure to suspect substances, which 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 certains type 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.

Supporters of MCS sufferers argue that MCS should be taken seriously, and most importantly, that people suffering from it (again, regardless whether it is a 'real' or psychosomatic problem) should not be treated with disdain or labeled fakers because they suffer from real problems. They say that the debate on MCS is about the cause and not about the effects.

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 garden chemicals
  • shampoos, hairsprays and personal care products
  • dishwashing liquid
  • most glues (including carpet glue), varnishes, polishes, paints, solvents and paint-thinners
  • petroleum-based products (petroleum jelly etc)

In particular, offgassing chemicals (some odorless, some not) are suspect. Solvents are very suspect, because there is no debate in medical science that these can cause permanent braindamage 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.

The list is actually endless. Since one basic belief is that buildup of trace-levels of chemicals is the cause of MCS, almost any substance is suspect, since every substance is fatal if the dose is high enough. The minerals in mineral water for instance will are fatal if about 7200 liters of it are drunk within one hour. This is of course physically impossible, but with a buildup up over time of substances, causing traces of substances to be able to trigger effects, as claimed by Clinical Ecologists, it is obvious that any substance becomes suspect.

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.

See also Gulf War syndrome, migraine.

Further reading

  • An Alternative Approach to Allergies: Revised Edition by Theron G. Randolph, M.D., and Ralph W. Moss, Ph.D. ISBN 0060916931
  • Allergic to the Twentieth Century by Peter Radetsky, ISBN 0316732214
  • Chemical Exposures:Low Levles and High Stakes Second Edition by Nicholas Ashford and Claudia Miller ISBN 0471292400

External links



  • Art and Cultures
    • Art (
    • Architecture (
    • Cultures (
    • Music (
    • Musical Instruments (
  • Biographies (
  • Clipart (
  • Geography (
    • Countries of the World (
    • Maps (
    • Flags (
    • Continents (
  • History (
    • Ancient Civilizations (
    • Industrial Revolution (
    • Middle Ages (
    • Prehistory (
    • Renaissance (
    • Timelines (
    • United States (
    • Wars (
    • World History (
  • Human Body (
  • Mathematics (
  • Reference (
  • Science (
    • Animals (
    • Aviation (
    • Dinosaurs (
    • Earth (
    • Inventions (
    • Physical Science (
    • Plants (
    • Scientists (
  • Social Studies (
    • Anthropology (
    • Economics (
    • Government (
    • Religion (
    • Holidays (
  • Space and Astronomy
    • Solar System (
    • Planets (
  • Sports (
  • Timelines (
  • Weather (
  • US States (


  • Home Page (
  • Contact Us (

  • Clip Art (
Personal tools