Multiple Chemical Sensitivity (MCS) – Refuting the Skeptics

Even though millions of people are sensitive to certain chemicals, some members of the medical establishment have long viewed multiple chemical sensitivity (MCS) with skepticism.

At a physicians’ conference last year, one immunologist told me that MCS is “all in their heads.” At the same conference, another physician told me that he has suffered from MCS ever since medical school, when he was exposed to high levels of formaldehyde during dissections.

I know that MCS exists because I have suffered from it. When I was a child with severe allergies, my mom picked up one of my friends on the way to school every morning. My friend wore perfume (quite a bit of it), and every time she got in the car, I got a headache and started sneezing. I often had to roll down my window to avoid the chemical odor.

Even though some doctors still think it’s “all in your head,” several years ago Martin Pall, professor of biochemistry at Washington State University wrote a paper that describes mechanims of MCS.

Professor Martin explains, “Multiple Chemical Sensitivity (MCS), where people report being exquisitely sensitive to a wide range of organic chemicals, is almost always described as being ‘controversial.’ The main source of this supposed controversy is that there has been no plausible physiological mechanism for MCS and consequently, it was difficult to interpret the puzzling reported features of this condition. As discussed below, this is no longer true and consequently the main source of such controversy has been laid to rest.”

“The descriptions of MCS made by a several different research groups are remarkably consistent. MCS sufferers report being hypersensitive to a wide variety of hydrophobic organic solvents, including gasoline vapor, perfume, diesel or jet engine exhaust, new or remodeled buildings where building materials or carpeting has outgassed various solvents, vapors associated with copy machines, many solvents used in industrial settings, cleaning materials and cigarette and other smoke. Each of these is known to have volatile hydrophobic organic compounds as a prominent part of its composition.”

Without going into too much scientific detail, Martin put together a theory of MCS and answered the most puzzling questions about this widespread condition:

How do pesticides (organophosphates and carbamates) and hydrophobic organic solvents act to induce cases of MCS? Each acts to initiate a vicious cycle mechanism involving NMDA receptors, nitric oxide and peroxynitrite in the brain, with organophosphates/carbamates acting via one known mechanism and hydrophobic organic solvents acting by another mechanism.

How do hydrophobic organic solvents act to trigger the symptoms of MCS? They act by the same mechanism proposed for such solvents in #1 above.

Why is MCS chronic? Presumably for two reasons: Because of the several positive feedback loops that maintain the elevated nitric oxide/peroxynitrite/NMDA activity and also because changes in the synapses of the brain may be long term.

How can MCS victims be so exquisitely sensitive to organic solvents? Because there are four different mechanisms by which nitric oxide or peroxynitrite act to produce the response, with the combination of all four acting synergistically to produce such exquisite sensitivity. The mechanisms of all four are well documented although their relevance to MCS can be questioned.

How can we explain the overlaps of MCS with chronic fatigue syndrome, fibromyalgia, posttraumatic stress disorder and Gulf War syndrome? All of these are proposed to involve excessive nitric oxide and peroxynitrite and all may also involved excessive NMDA activity.

To see Martin’s full explanation, see his entire paper at

vapor steam cleanerIf you suffer from MCS, eliminate chemicals like pesticides and cleaning agents from your home. Use traps for pest control, and replace chemical cleaners with a vapor steam cleaner.

MCS Air PurifiersEliminate off-gassed chemicals in the air with an air purifier. Some air purifiers are specially made for people who suffer from multiple chemical sensitivity. For more information, see Air Purifiers for MCS.

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