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Multiple Chemical Sensitivity (MCS) - What Is It?





by Dr. Sarah Myhill


MCS - What Is It?

The body is daily exposed to substances which have the ability to damage or even kill it. From an evolutionary point of view, these substances have traditionally included viruses, bacteria, yeasts and fungi, poisonous foods, and other such nasties. The body reacts against these substances via the immune system. The immune system learns to recognize the substances and react against them with inflammation, which effectively kills or denatures that substance.

The problem is that in recent years man has developed a new range of toxic substances, such as pesticides and solvents. These chemicals are equally toxic to the body and the body recognizes this. To cause damage the chemical either has to be particularly toxic or present in a high concentration, and this appears to switch on the immune mechanism for identifying and reacting against chemicals.

Everybody knows that once you have had measles you are protected against future attacks because the immune system has learned to recognize the measles virus and attacks it vigorously before the numbers can build up and cause an infection.

Exactly the same principle (but possibly a different mechanism) applies with chemical sensitivity. Once the body has been damaged by an overwhelming dose or a toxic dose of a chemical, the body learns to recognize very tiny amounts of this chemical and reacts against it accordingly. This is probably the first step in developing chemical sensitivity.


The ‘Spreading Phenomenon’

However, chemicals are often related - and the next step which happens is that the body then starts to react against other, related chemicals. This is called the spreading phenomenon and results in multiple chemical sensitivity, whereby one reacts to lots of different chemicals.

The body has more than one line of defense. The immune system is just one, but we are intelligent beings and just as one might choose to avoid spending time with somebody who has got influenza, one also chooses to avoid inadvertent exposure to chemicals.

The presence of these chemicals can often be sensed by smell, and the body quickly learns that smelling a substance will subsequently result in severe symptoms. Indeed this quickly becomes a conditioned response (just as with Pavlov’s dogs), whereby just the smell of a chemical will induce the symptoms.

So multiple chemical sensitivity is:

  • An acquired sensitivity to chemicals
  • Which may be noxious initially, but often innocuous subsequently,
  • Which is triggered by a tiny exposure to a chemical,
  • Which may result in a multiplicity of symptoms,
  • Which may take hours or even days to clear.


A Matter of Degree

There are many degrees of multiple chemical sensitivity. In a random telephone survey of United States citizens, it was shown that 7.8% of the population said that they were intolerant of certain chemicals and avoided them.

Many people will tell you that:

  • Perfume makes them sneeze,
  • Petrol fumes cause nausea,
  • Alcohol makes them feel spaced out and dizzy,
  • Paint fumes may cause headache.

These are the minor and easily avoidable chemical incitants. However, for some people their sensitivity is so severe that they are unable to tolerate even the slightest exposure to chemicals, as a result of which they have to live in carefully controlled clean environments. The slightest exposure to chemicals causes severe symptoms and they are simply unable to go into an uncontrolled environment.

These people are made prisoners in their own home, being unable to go out into cars, travel into any public place, or meet other people who may be wearing the very cosmetics, perfumes and fabrics which make them ill.


MCS – What are the Symptoms?

Multiple chemical sensitivity is the great mimic. It can produce almost any symptom. In her paper "Toxicent-Induced Loss of Tolerance" [TILT], Professor Claudia S. Miller, MD [a leading chemical exposure and sensitivity expert at the University of Texas Health Science Center] gives the following list of general symptoms:

Neuromuscular; Cardiac; Loss of consciousness; Heart pounding; Stumbling/dragging foot; Rapid heart rate; Seizures; Irregular heart rate; Print moving/vibrating on page; Chest discomfort; Feeling off balance; Affective Tingling in fingers/toes; Feeling tense/nervous; Double vision; Uncontrollable crying; Muscle jerking; Feeling irritable/edgy; Fainting; Depressed feelings; Numbness in fingers/toes; Thoughts of suicide; Clumsiness; Nerves feel like vibrating; Problems focusing eyes; Sudden rage; Cold or blue nails/fingers; Loss of motivation; Uncontrollable sleepiness; Trembling hands; Head-related: Insomnia; Head fullness/pressure Airway: Tender face/sinuses; Cough; Sinus infections; Bronchitis; Tightness in face/scalp; Asthma or wheezing; Brain feels swollen; Post nasal drainage; Ringing in ears; Excessive mucus production; Headache; Shortness of breath; Feeling groggy; Eye burning/irritation; Musculoskeletal; Susceptible to infections; Joint pain; Dry eyes; Muscle aches; Enlarged/tender lymph nodes; Weak legs; Hoarseness; Weak arms; Cognitive; General stiffness; Memory difficulties; Cramps in toes/legs; Problems with spelling; Painful trigger points; Slowed responses; Gastrointestinal; Problems with arithmetic; Abdominal gas; Problems with handwriting; Foul gas; Difficult concentration; Problems digesting food; Difficulty making decisions; Abdominal swelling/bloating; Speech difficulty; Foul burping; Feelings of unreality/spacey; Diarrhoea; Other Abdominal pain/cramping; Feeling tired/lethargic; Constipation; Dizziness/lightheadedness.

My experience is that:

  • The most common systemic symptoms are foggy brain (inability to think clearly), headache, fatigue and dizzy spells.
  • The most common local symptoms are rhinitis (runny nose), conjunctivitis (itchy eyes) and asthma.


MCS – Who Gets It?

Multiple chemical sensitivity can occur in anybody, but very often there is some overwhelming exposure to a toxic substance which triggers it in that person. The groups of workers with well documented chemical sensitivity following occupational exposure are as follows:

  • Gulf war veterans;
  • Homeowners exposed to pentachlorophenol wood preservatives;
  • Homeowners/Office workers exposed to organophosphate/carbamate pesticides;
  • Hospital workers;
  • Sheep dippers exposed to organophosphate pesticides;
  • Radiology workers exposed to film developing chemicals;
  • Solvent-exposed workers;
  • Office workers and teachers (various indoor air exposures) - otherwise known as sick building syndrome;
  • Homeowners/office workers exposed to volatile organic compounds associated with remodeling - such as new carpets, new paint and new office furniture;
  • Casino workers exposed to mixed pesticides;
  • Implant recipients;
  • Chemical weapons production workers;
  • Agricultural workers exposed to organophosphate pesticides.

In all these cases there has been excessive exposure to chemicals with MCS resulting. It is quite clear from inspection of these lists that the reason MCS is denied by the establishment is because all these illnesses are caused by exposures in the workplace. To admit that MCS exists and is as a result of these exposures would result in major litigation.

View the very BEST Environmental Illness Videos!

1. Your Health is Governed by Your Environment | Prof. BM Hegde | TEDx Talk

2. Demystifying Multiple Chemical Sensitivity

3. Social Determinants of Health - An Introduction 



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