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Multiple Chemical Sensitivity

Review of the State of the Art in Epidemiology, Diagnosis, and Future Perspectives

Tuuminen, Tamara MD, PhD

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Journal of Occupational and Environmental Medicine: August 2018 - Volume 60 - Issue 8 - p e429
doi: 10.1097/JOM.0000000000001369
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To the Editor:

Sabrina Rossi and Alessio Pitidis performed an extensive literature survey on nearly 100 publications and combined the latest knowledge on multiple chemical sensitivity (MCS).1 However, their paper is highly contradictory, and it seems that the authors do not believe themselves what they have written.

First, the authors described the natural course of the disease going in stages from the zero which means tolerance to various environmental factors. The tolerance may be lost by increasing sensitization to multiple chemical substances. This is called toxicant induced loss of tolerance.2 The end stage of the disease is the Stage three which is a devastating condition called deterioration with chronic inflammation that involves almost all organs.

Secondly, the authors cited many papers pointing to the fact of oxidative stress reaction and a misbalance in detoxification system. The authors cited the papers showing neurogenic inflammation and hyperreactivity to stimuli detected by accurate modern imaging techniques. The authors made a very fair conclusion that in case of occupational nature of MCS, avoidance of the inflicting substances should be pursued. The authors even proposed the use of an electronic Nose, a portable device to help the workers stay at bay from the possible triggers. Importantly, the authors suggested that “sensitization trials on humans could be hazardous because of the possible damage and stress….” The authors also pointed out that there are metabolic and genetic predispositions to develop MCS.

Aren’t these statements sufficient to draw a conclusion about the somatic nature of MCS?

For the sake of objectiveness of their review, papers claiming the psychiatric origin of MCS were cited too. However, I would expect the author's more critical position on the use of provocation tests, many of them performed in a very poor study design which was not discussed in the paper.

Regretfully, the authors ended up with a statement that “… the absence of stronger evidence in MCS diagnosis protocols, based on specific measures of exposure to chemicals and their biological and physiological effects, could lead to erroneous estimation of the impact of MCS ….” With this phrase the authors have revoked all the evidence they have retrieved from the literature. Again, we hear about insufficient evidence for the disease. May I ask the authors: what is the sufficient evidence and how high the incidence and prevalence of the disease should rise to make the authors accept MCS as a clinical entity? Are we living Déjà vu when health hazards of tobacco smoking did not reach sufficient evidence?

It seems that the authors have no clues to the pathogenesis of MCS. They wrote about suspicion of intoxication at low dosages, which is not the case with MCS. MCS is not intoxication. It is an overwhelmed hypersensitivity of sensory receptors with insidious chronic inflammation and a break-up of the body's redox system.3–5 The major flaw of the paper is that the authors dropped from their review the fundamental research of Professor Martin Pall3,4 and clinical expertise of Doctor William Rea.5

In conclusion, because of the ambiguous position of the authors with no clear message the mission of their paper remained vague. At least, it does not improve patients’ rights to get appropriate medical help and reimbursement when the disease is of occupation nature.


1. Rossi S, Pitidis A. Multiple chemical sensitivity: review of the state of the art in epidemiology, diagnosis, and future perspectives. J Occup Environ Med 2018; 60:138–146.
2. Miller CS. Toxicant-induced loss of tolerance. Addiction 2001; 96:115–137.
3. Pall ML. “Explaining ‘Unexplained Illness’: Disease Paradigm for Chronic Fatigue Syndrome, Multiple Chemical Sensitivity, Fibromyalgia, Post-Traumatic Stress Disorder, Gulf War Syndrome and Others”, 16 Chapter book. New York: Harrington Park (Haworth) Press; 2007.
4. Pall ML. Ballantyne B, Marrs TC, Syversen T. General and applied toxicology (Chapter XX). John Wiley & Sons, Multiple Chemical Sensitivity: Toxicological Questions and Mechanisms. London: 2009.
5. Rea WJ. Chemical Sensitivity Vol. 3-Clinical Manifestation of Pollutant Overload; 1996: 1105–2015. Available at: Accessed May 5, 2018.
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