Multiple Chemical Sensitivity

Multiple Chemical Sensitivity (MCS) is sometimes referred to as TILT the prevalence is
Around 1% of people are affected by MCS to varying degrees on a more ongoing basis, up to 16% of people report heightened sensitivities to some chemicals [SA Health Department] [Caress][Genius]


Multiple chemical sensitivity; also referred to as Toxicant Induced Loss of Tolerance TILT is not an allergy. However it can be likened to an allergy in that people with chemical sensitivity can experience very unpleasant symptoms from exposures to low levels of a substance that would not normally be a problem for most people.

“Some people are more sensitive (i.e. hypersensitive) to formaldehyde effects than others. For the general population, skin exposure to formaldehyde solutions with concentrations of around 1-2% is likely to irritate skin. However, hypersensitive people can develop contact dermatitis after exposure to concentrations of formaldehyde as low as 0.003%.” SA Health

While people with allergies have a hypersensitive immune system (IgE antibodies); people with chemical sensitivities have a hypersensitive nervous system. And while people with allergies generally feel symptoms immediately this is not always the case for people with sensitivities sometimes sensitivity reactions are delayed and masked; making the trigger difficult to identify.

“Many patients, perhaps the majority, are not even aware they have intolerances, due to a phenomenon called “masking”. Masking tends to hide the relationship between an individual’s symptoms and triggering exposures. It has several interactive components. One masking component, apposition, occurs when people become intolerant to many different substances. As these individuals go through the day multiple symptoms, triggered by fragrances, hair spray, vehicle exhaust, foods, medications, etc. overlap, creating a confusing array of symptoms. No one cause can be isolated because there is too much background noise. Addiction to caffeine, nicotine, or alcohol can also mask the effects of chemical inhalant exposures. People exposed to the same substance more than once every 4–7 days tend to habituate to that substance. Habituation also masks responses. Masking helps explain why symptoms vary from person to person, and from day to day in the same individual.” (Miller C.S., Toxicant-induced loss of tolerance, Addiction, 96 (1): 115 – 139 (2000))

Often reactions experienced by people with chemical sensitivity are dose and exposure related

and are only experienced after repeated exposures to substances and once they exceed their tolerance levels which vary from person to person. However, people with more severe chemical sensitivity (multiple chemical sensitivity) may notice symptoms immediately; for example when they enter a fragranced shop and find they can not breathe very well or their eyes burn.

Symptoms experienced by people with chemical sensitivity vary in type; duration and severity and symptoms can be just about anything. It depends on a persons individual genetic vulnerability and the level to which they have become neurally sensitized. With symptoms varying depending on the level of toxicity; inflammation (particularly nerve inflammation) and stress they are experiencing at any given point in time.

In regards to toxicity this can mean a build up toxic compounds or metabolic by-products periodically due to impaired liver detoxification (FLDP Test or Detoxi Genomics not standard liver test) and enzyme depletion. Or a toxic buildup of neurotoxic substances like solvents; mercury or pesticides in the nervous system; organs and brain (neurotoxicity) or neurotoxicity due to very heightened levels of stress hormones; or very heightened NMDA activity and glutamine (excitotoxicity) or a combination of these.

People with more severe toxicity; inflammation and stress often also have nerve injury or toxic neuropathy (also see Chemicals and Nervous System - Dana Guide). This can often be reversed by reducing chemical exposures and stress when combined with appropriate medical treatment; but not always, The more ongoing and severe the injury the more difficult (sometimes extremely difficult and even impossible) this can be. For these people exposures and symptoms will most likely need to be managed for life, however symptoms can be significantly reduced by reducing chemical and stimuli exposures.

The most common symptoms experienced by people with chemical sensitivity are:

Heightened anxiety
Random Aches and pains
Digestive upsets
Memory and Concentration difficulties
Sleep difficulties
Joint and muscular pain

These symptoms are very similar to those experienced by people with chronic fatigue syndrome and fibromyalgia because these are related conditions that many people with chemical sensitivity also experience. The symptoms are also very similar to those experienced by people with depression and stress disorders. This is because exposures to chemicals (once a person has become sensitized to them - particularly if injury at a cellular level or toxicity is occuring) not only affects specific organs and system but also the same areas of the brain and the same nervous system; immune system and endocrine (hormone) system pathways as stress does.

Often people with chemical sensitivities are also experiencing a stress disorders (no wonder!) and for some people getting treatment for the stress disorder (particularly in the earlier stages of chemical sensitivity) may reduce and even completely alleviate sensitivities. However once sensitivities are severe and coupled with hypocortisolism - low levels of cortisol and more severe liver detoxification impairment standard treatments for stress disorders such as cognitive behavioural therapy (CBT) or medications for depression are generally not helpful and in fact may make matters worse. This is particularly true; if the person is also experiencing nerve injury known as neuropathy. This typically causes a wide range of symptoms as well. Including nerve pain; stabbing; tingling or burnng.

Causes of multiple chemical sensitivity

Multiple chemical sensitivity also known as Toxicant Induced Loss of Tolerance (TILT) is thought to be initiated by toxicity; enzyme depletion and chemical injury in people who have been exposed to high levels of certain chemicals; (e.g. pesticides; certain solvents; carbon monoxide; formaldehyde; mercury; other) or in people with a genetically vulnerable profile where enzymes required for efficient liver detoxification may be missing when they are exposed to chemicals at non toxic doses but above their capacity to effectively detoxify them for a long period of time. As people experiencing heightened stress due to infection; ongoing illness; physical injury or unresolved psychological trauma often experience imbalances to their autonomic nervous system which can affect enzyme production; nutrient absorption and liver detoxification; these people are also more vulnerable to chemical injury and developing chemical sensitivity.

While the causes of ongoing chemical sensitivities are not fully understand it is thought that once initiated people get stuck on a self perpetuating loop. Dr Martin Pall postulates that elevated nitric oxide; peroxynitrite; NMDA; glutamine and depletion of ATP required for sufficient energy production maintains the loop and sensitivities. He calls this the Nasty NO/OONO Disease cycle. To date Pall's models seems to be the most comprehensive and accepted according to the researchers at James Madison University.

To treat multiple chemical sensitivity it appears important to:

reduce toxicity; inflammation (particularly nerve inflammation) and stress as these will all elevate nitric oxide; peroxynitrite; NMDA activity; glutamine and neural sensitisations (sensitisations are simply changes to the nervous system that heightens pain and stimuli sensitivity that may worsen over time due to repetitive exposures to stressors and irritants due to time dependent sensitisation). However treatment generally needs to be PACED quite slowly; particularly in the later stages of MCS [See MCS categories] in order to calm the hyper-responsiveness of the nervous system; HPA axis and aspects of the immune system - all of which can have a cascading effect on multiple systems.

The following in summary form were advised to me by my various health professionals - and have now alleviated 50 of my symptoms and still counting

Work with a health professional with a good understanding of chemical sensitivities; usually a doctor trained in Nutrition and Environmental Medicine; who can guide treatment and identify and treat any other health conditions that may be contributing to ill health

Reduce a persons overall stress load: (I follow my R.E.S.H.A.P.E guidelines for ease of memory based on Treatment Protocols and have found taking a goal setting approach best - my R.E.S.H.A.P.E guidelines can be found at

Improve indoor air quality at home and choose safer products

Eat a healthy balanced wholefood diet adjusted for food intolerance

Sometimes medications and supplements can be helpful and may even reduce sensitivities. However this needs to be assessed on an individual basis by a health professional taking into consideration a person’s level of sensitivities to medicines and substances in supplements; particularly plant substances if a person is also salicylate intolerant.

Learn to effectively manage symptom flare-ups, in fact create a symptom management plant

Photo Source: Article Extreme Chemical Sensitivity Makes Sufferers Allergic to Life by Jill Neimark Discovery Magazine [Click Here to view article]

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For full bibliography click here