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Multiple Chemical Sensitivity

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

Rossi, Sabrina MSc

Journal of Occupational and Environmental Medicine: August 2018 - Volume 60 - Issue 8 - p e430
doi: 10.1097/JOM.0000000000001368

Department of Environmental and Health, National Italian Institute of Health, Viale Regina Elena, Rome, Italy.

Address correspondence to: Sabrina Rossi, MSc, Department of Environmental and Health, National Italian Institute of Health, Viale regina Elena 299-00161 Rome, Italy (

The authors have no conflicts of interest.

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To the Editor:

We make a premise: we have set up a review just to analyze some topics related to the multiple chemical sensitivity (MCS), although aware that they were not exhaustive.

First of all, since our review is an update, we focused (on the basis of the results obtained from the bibliographic research), on providing a general overview of the articles, placing greater emphasis on the latest evidence in the epidemiological and diagnostic field.

On the other side, both therapies and the rights of patients to have the maximum available care, at present, were out of the scope of our review. Sick Building Syndrome and Multiple Drug Intolerance Syndrome1 are others topics probably related to MCS that we have not investigated.

Being a “systematical” review, some reviews such as those of Dr. WJ Rea and Dr. Martin Pall have not been cited directly, although they are present indirectly in the bibliographic references of the articles we cited and in the introduction. The relevant theories have been expressed, analyzed, and retraced in the various articles we cited.

On the other hand, regarding the fact that it is not a question of chronic low-dose intoxication but of super sensitivity of the sensory receptors with inflammation and imbalance of the redox system, it is absolutely not in contrast with what the authors have assumed so far, because in the continuity of exposure, deterioration can occur.

I take this opportunity to say that in the scientific community, not everyone agrees that there is necessarily a deterioration even in the event that the exhibition proceeds. This question could be an evident problem for a “chemiofobic diagnosis” and psichosomatic theory.

We agree that, depending on the stage and in the absence of abstention from exposure as far as possible, the MCS moves from a stage of partial reversibility to overt disease that will then be diagnosed as such, with the risk that the path that led to the disease is not identified. At the bottom of our response we have included one reference in which you can find known (chapter 33—occupational toxicology—Peter S. Thorne) an occupational toxicology scheme that explains the path and provide for a careful control in the workplace.2

We have noted a fairly small number of articles related to the professional sector in which there could be greater control and analysis. We have suggested refocusing attention on occupational exposure because it could be a more suitable mean to perform both epidemiological and clinical analysis on MCS, without having to perform ad hoc experimental studies on patients.

Of course, restricting the reference sample does not mean also denying the environmental nature. The business implications can be very painful, because they expose individuals to repercussions of various order and degree that add to the diagnosis difficulty: lack of respect and understanding at working level, with relative loss of the job, the labeling of mental illness, which further affects the accuracy of the analysis in addition to all the ethical, social, and care consequences that could derive from it.

You ask me how high has to be the incidence or prevalence of a syndrome so to be considered as a clinical entity. It can also concern a limited but well identified number of cases …. with accurate evaluation case by case! The vagueness that you find in the conclusions of our article is what clearly emerge from the several articles we read. Our considerations are instead expressed in the part of the discussion in which we have not at all thought to deny MCS, but we have underlined that it is currently still considered an idiopathic syndrome and that has not yet been assigned a precise code in the International Classification of Diseases.

Your further criticism that our article would not help patients to seek valid medical help and reimbursement when the illness is of a professional nature can’t be accepted because, having not ourselves performed specific research in this direction, we can’t express. We, therefore, specify that our intent was and is exactly the opposite: to aid the prevention, the correct diagnosis, the recognition, and the care of MCS, in favor of the wellness of the person, intended in physical, mental, social, and working terms! It is, therefore, necessary that the MCS gets more into the common scientific language and that internationally accepted diagnostic criteria be defined, avoiding potential dangerous diagnostic errors.

We, therefore, hope that a proper diagnosis, that links work exposure and MCS in a clear relationship of cause–effect, will help patients to request compensation (eg, see also chapter 24 toxic effects of solvents and vapors).2

We hope to read a relevant work of you on the argument.

Best regards.

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1. Niedoszytko M, Chelminska M, Buss T, Roik E, Jassem E. Drug intolerance in patients with idiopathic environmental intolerance syndrome. Int J Clin Pract 2006; 60:1327–1329.
2. Casarett L, Doull's Essen J. In: Curtis DK, ed. Toxicology, 7th ed. The McGraw-Hill Companies, Inc. (2009) Copyright. All rights reserved.
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