MCS/ES Symptoms and Environmental Incitants

sensitive to pollution 3

Information about the materials most likely to cause adverse health effects, and the kinds of symptoms commonly experienced from exposures, copied from the 2007 Canadian Human Rights Commission’s  document “The Medical Perspective on Environmental Sensitivities By: Margaret E. Sears (M.Eng., Ph.D.), and a few other resources and links follow:


PDF of document: 2007 CHRC The Medical Perspective on Environmental Sensitivities

Agents initiating the condition of environmental sensitivities and triggering reactions

People with sensitivities have individual susceptibilities to various environmental factors. As seen in Table 6, the more common agents that trigger reactions in susceptible people include pesticides, volatile organic compounds (VOCs) such as solvents, perfumes, formaldehyde and other petrochemicals, vehicle exhaust, moulds, pollens, foods, animal danders and electromagnetic phenomena. These may arise from the workplace structure, furnishings, equipment, exterior surroundings, cleaning products or from co-workers and clients. Other aspects of the environment, including electromagnetic radiation, currents and fields, lighting, humidity, heat, cold and noise may also exacerbate environmental sensitivities.

Once people are initially sensitized to low levels of environmental factors, if the condition is not recognised and addressed they may experience reactions triggered by a broader range of exposures. In this two-stage process, environmental sensitivities may develop gradually with chronic exposure to relatively low levels of chemicals as seen in “sick buildings,” or suddenly after a major exposure to an environmental disaster or a chemical spill.

Table 6: Typical agents that trigger reactions in susceptible individuals (and may contribute to initiation of environmental sensitivities)3,28,60,70,71


Type of Incitant

Examples of incitants

Examples of sources/products

Volatile organic compounds










Off-gassing mixtures




Urea formaldehyde foam insulation*

Wood glues (e.g plywood and chipboard)**



Paint thinner and stripper


Air fresheners

Perfumes, personal care products

Household cleaning agents – e.g. detergents

Fabric softeners

Equipment (e.g. computers)



Inks in books, periodicals

Fuel, Oil

Combustion products

Tobacco smoke

Vehicle exhaust

Barbeque or wood smoke


Buses, trucks, cars

Barbeques, wood stoves

Microbial products




Mould or bacterial metabolites

Mould or bacteria in structures

Mould or bacteria in air conditioning/air handling systems

Microbes in older documents

Musty furnishings

Soil (plants)






Products used to kill insects

Products used to kill weeds outside

Products used to kill fungi

Swimming pool chemicals, including chlorine

Natural inhalants



Animal dander

Tree pollens (spring)

Ragweed (August/September)

Dogs, cats, horses etc


Allergenic proteins



Individual-specific (e.g. pungent foods)

Peanuts, milk, gluten in grains

Sulphites in dried fruits and wine

Monosodium glutamate (MSG)

Curry, cinnamon

Electromagnetic radiation



Radiowaves and Microwaves




Very low frequency

   electromagnetic fields

Ground currents


Video display screens

Fluorescent light bulbs, “dirty electricity,” wiring problems, energy-efficient devices, computers, televisions, telecommunications equipment

Power lines


Power supply services that allow current

   to flow through the ground, pipes or


Other factors



Workplace infrastructure

* urea-formaldehyde insulation has been banned in Canada

**  formaldehyde-containing glues are banned in new products in many countries including Europe, Japan and China


Symptoms of environmental sensitivities are unique to the individual. Some possible symptoms are summarised in Table 7.

Sensitivity reactions to chemicals may vary for acute or chronic exposures. A single, isolated low-level exposure (e.g. perfume on someone several seats away in the theatre or bus, that is not obviously harming the wearer) may cause significant symptoms such as headache, confusion, breathing difficulties or loss of balance in a person with environmental sensitivities. These symptoms may take minutes, hours or days to resolve. However, regular exposure to something to which one is sensitive may lead to habituation or “masking,” and chronic ill-health that may even be accepted as normal.3  Habituation is also the reason why research into sensitivities would benefit from an environmental medical unit with high quality air, water, food and surroundings, so that affected people attain a “baseline” unmasked level of health.72,73  A study found that people with environmental sensitivities do not adjust as quickly as healthy volunteers to research situations, so deficiencies in trial design may explain inconclusive studies in the scientific literature.72,74

Table 7:  Environmental sensitivity symptoms/reactions5,60,75,76


Body System


Nervous System

Heightened sense of smell

Difficulty concentrating

Difficulty remembering

Apparent variability in mental processes

Feeling dull or groggy

Feeling “spacey”


Restlessness, hyperactivity, agitation, insomnia


Lack of coordination or balance




Upper Respiratory System

Stuffy nose, itchy nose (the “allergic salute”)

Blocked ears

Sinus stuffiness, pain, infections

Lower Respiratory System


Wheezing, shortness of breath, heavy chest


Frequent bronchitis or pneumonia


Red, watery eyes

Dark circles under eyes

Pain in eyes

Blurred, disturbed vision

Gastrointestinal System











Abdominal pain

Endocrine System

Fatigue, lethargy

Blood sugar fluctuations

Musculoskeletal System

Joint and muscle pain in the extremities and/or back

Muscle twitching or spasms

Muscle weakness

Cardiovascular System

Rapid or irregular heartbeat

Cold extremities

High or low blood pressure

(Dermatological System)

Flushing (whole body, or isolated, such as ears, nose or cheeks)



Other rashes


Genitourinary System

Frequency and urgency to urinate

Painful bladder spasms


Improving indoor environmental quality will potentially benefit many more people than the individual identified with sensitivities. Workers are more productive and general symptoms of “sick building syndrome” may improve when ventilation is improved 79-82 or a pollution source is removed from offices.83,84  Children are healthier and learn better when indoor environmental quality is improved in schools.8,85-87


“Sensitivities may be initiated by a range of environmental factors and once the condition is initiated, reactions may be triggered by a broadening array of incitants. Environmental sensitivities may affect every system in the body, so multiple symptoms are possible, with variation among individuals. Neurological symptoms are almost universal. Common incitants are summarised in Table 6 and symptoms are summarised in Table 7. The impact of environmental sensitivities on workers’ performance may range from mild (e.g. habituation to chronic exposures such that performance may be sub-optimal, although not “abnormal”) to severe impairment such that work is impossible. 

The health and ability to work for those with environmental sensitivities rests with the choices and actions of others, such as building managers, co-workers and clients.”

NOTE: that document was designed with those people in mind who have MCS/ES and are still well enough and able to work as long as accommodations are received. It does not take into consideration what happens to people if early diagnosis and accommodations are NOT received. In these cases, people are no longer able to work, the symptoms can become severe to life threatening, and recovery times from exposures can last from days to months. Of course, it is quite challenging to avoid certain types of exposures these days (fragrance chemicals, wireless technology), so the effects can be compounded in severity (not just masked).  Therefore, early diagnosis and steps to avoid exposures and exacerbation are required to prevent people (and their families)  from having to experience that high a level of suffering

See also:

the American Academy of Environmental Medicine

Chemical Sensitivity


Chemical sensitivity is a physical reality that our society will have to recognize and address. The word “sensitivity” implies that tiny exposures lead to big problems. The 90,000 chemicals commonly circulating in our modern world appear to be causing considerably more problems for humans than are typically recognized. Chemically sensitive persons, when reacting to even small chemical exposures, suffer with various symptoms that range in intensity from being unpleasant to being temporarily or even permanently disabling. Only too frequently this condition is unrecognized as it progressively leads to poor health, reduced activity, stressed social relationships and reduced job productivity.   …

“It is extremely unfortunate that, despite the growing body of research literature in highly respected, peer-reviewed journals that demonstrates very clearly the physical/biochemical reality of both chemical toxicity and chemical sensitization, many persons in positions of authority remain unaware of the widespread prevalence and seriousness of environmental illness and are still oblivious to the adverse health effects of the multitude of man-made toxins contaminating our air, our water, and our food.”

More at:

Multiple Chemical Sensitivity:
Toxicological and Sensitivity Mechanisms

Martin L. Pall
Professor Emeritus of Biochemistry and Basic Medical Sciences,
Washington State University and Research Director of the Tenth Paradigm Research Group

MCS Is a Reaction to Chemicals,
Not Odors

It should be clear from the above, that chemicals acting in MCS are not acting on the classic olfactory receptors (15,16), but rather are acting as toxicants.  This is opposite many published but undocumented claims that MCS is a response to odors.  There is additional evidence arguing against the view that MCS is a reaction to odors.  MCS sufferers who are acosmic, having no sense of smell, people who have intense nasal congestion and people whose nasal epithelia have been blocked off with nose clips can all be highly chemically sensitive (1,4).  This does not necessarily mean that MCS never impacts the olfactory system.  It simply  means that MCS is not primarily an olfactory response.  A recent study, confirmed this view, showing that the olfactory center in the brain in people with MCS was less sensitive to activation by chemical exposure than in normal controls, rather than being more sensitive (17).

The information there is apparently essentially the same as is found in the text

Pall M.L.  (2009)  Multiple chemical sensitivity:  toxicological questions and mechanismsWiley & Sons, New York, in press.

Having MCS/ES alone is bad enough, sadly though, too many people also have FM, and or CFS/ME along with MCS, in addition to other chronic conditions. Accessing health care to treat any of these is extremely difficult when one has MCS/ES.

Frequencies of MCS Co-diagnoses for Canadian Target Population*

– Chronic condition
– % of people with MCS having this additional diagnosis…
– % of target population having this diagnosis…

Other allergies (not food) 61.1   26.6
Other back problems (not arthritis or fibromyalgia) 39.7   18.8
Arthritis/rheumatism 38.5   16.4
Food Allergies 27.3   7.2
Migraine headache 26.3   10.5
Asthma 25.7   8.3
High blood pressure 24.5   14.9
Mood disorder 15.9   5.6
Anxiety Disorder 14.5   4.4
Thyroid condition 13.8   5.6
Bowel disorder 13.1   3.9
Bronchitis 11.4   2.5
Fibromyalgia 10.0   1.4
Chronic Fatigue Syndrome 9.9   1.2
Heart disease 9.8   4.7
Cataracts 9.1   4.2
Stomach/Intestinal ulcers 8.9   3.1
Diabetes 6.9   4.9
Glaucoma 3.9   1.5
Effects of stroke 2.5   1.1
Cancer 2.3   1.4
Epilepsy 1.3   0.6

* “Delegitimizing those with ES-MCS, who may be warning us all of the need for toxics reduction, also tends to impede development of practical, precautionary, potentially preventive and cost-saving public health strategies.”

The consequences of poor indoor environmental quality and outdoor pollution have been known for decades. We really need more action to require that environments on this little planet are safe for all of us.

11 responses to “MCS/ES Symptoms and Environmental Incitants

  1. Even with early diagnosis and accommodations, it’s difficult to not go downhill when there are so many chemical irritants in the air. And if there is no safe home to stay in, sadly, people get worse. It’s sad that people often have to get really sick, having to avoid most situations just to stay semi-well. It’s like we have the sickness, then the exclusion from society and all that goes with it. I’m thankful for the online community we have :)

  2. Pingback: MCS FYI | Life in the City with a Future

  3. Thanks So much for this. I am working with the people of the Gulf oil Spill and really need an intake form for them. I have been searching everywhere for Physicians to treat this. Thank You.


  5. Pingback: Are the Wrong People in Solitary Confinement? | Seriously "Sensitive" to Pollution

  6. A great, informative ,helpful and very complete summary. Many thanks as always my friend.

  7. Available on the CHRC website in March 2021

    Policy on Environmental Sensitivities

    Individuals with environmental sensitivities experience a variety of adverse reactions. This medical condition is a disability. This document is a policy on environmental sensitivities. It provides guidance and strategies to minimize or eliminate exposure to triggers in the environment.

    The Medical Perspective on Environmental Sensitivities

    Are you an employer or service provider? Do you understand, from a medical perspective, why you need to accommodate individuals with environmental sensitivities? Do you know what policies or guidelines you should implement to ensure your environment is safe for all? This report summarizes scientific information about environmental sensitivities and addresses issues such as recognition by medical authorities, education and training, impact of environmental sensitivities in the workplace, and guidelines for accommodation.

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