The last edition of this Encyclopaedia did not contain articles on either sick building syndrome (SBS) or multiple chemical sensitivities (MCS) (the latter term was coined by Cullen, 1987). Most practitioners of occupational medicine are not comfortable with such symptomatically driven and frequently psychologically related phenomena, at least partly for the reason that patients with these syndromes do not respond reliably to the standard means of occupational health intervention, namely, exposure reduction. Non-occupational physicians in general medical practice also react similarly: patients with little verifiable pathology, such as those complaining of chronic fatigue syndrome or fibromyalgia, are regarded as more difficult to treat (and generally regard themselves as more disabled) than patients with deforming conditions such as rheumatoid arthritis. There is clearly less regulatory imperative for sick building syndrome and multiple chemical sensitivities than for the classic occupational syndromes such as lead intoxication or silicosis. This discomfort on the part of treating physicians and the lack of appropriate regulatory guidance is unfortunate, however understandable it may be, because it leads to minimization of the importance of these increasingly common, albeit largely subjective and non-lethal complaints. Since many workers with these conditions claim total disability, and few examples of cures can be found, multiple chemical sensitivities and sick building syndrome present important challenges to compensation systems.

In the developed world, since many classic occupational toxins are better controlled, symptomatic syndromes, such as those under present scrutiny that are associated with lower-level exposures, are assuming increasing recognition as significant economic and health concerns. Managers are frustrated by these conditions for a number of reasons. As there are no clear-cut regulatory requirements in most jurisdictions which cover indoor air or hypersusceptible individuals (with the important exception being persons with recognized allergic disorders), it is impossible for management to be certain whether or not they are in compliance. Agent-specific contaminant levels developed for industrial settings, such as the US Occupational Safety and Health Administration’s (OSHA’s) permissible exposure levels (PELs) or the American Conference of Governmental Industrial Hygienists’ (ACGIH’s) threshold limit values (TLVs), are clearly not able to prevent or predict symptomatic complaints in office and school workers. Finally, because of the apparent importance of individual susceptibility and psychological factors as determinants of response to low levels of contaminants, the impact of environmental interventions is not as predictable as many would like before a decision is taken to commit scarce building or maintenance resources. Often after complaints arise, a potential culprit such as elevated volatile organic compound levels with respect to outdoor air is found, and yet following remediation, complaints persist or reoccur.

Employees who suffer from symptoms of either sick building syndrome or multiple chemical sensitivities are often less productive and frequently accusatory when management or government is reluctant to commit themselves to interventions which cannot be reliably predicted to ameliorate symptoms. Clearly, occupational health providers are among the few key individuals who may be able to facilitate reasonable middle ground outcomes to the advantage of all concerned. This is true whether or not an underlying cause is low levels of contaminants, or even in the rare case of true mass hysteria, which may often have low-level environmental triggers. Using skill and sensitivity to address, evaluate and incorporate a combination of factors into solutions is an important approach to management.

Sick building syndrome is the more contained and definable of the two conditions, and has even had definitions established by the World Health Organization (1987). Although there is debate, both in general and in specific instances, about whether a given lesion is more attributable to individual workers or to the building, it is widely acknowledged, based on controlled exposure studies with volatile organic compounds, as well as survey epidemiology, that modifiable environmental factors do drive the kinds of symptom which are subsumed under the following article entitled Sick Building Syndrome. In that article, Michael Hodgson (1992) details the triad of personal, work activity and building factors which may contribute in various proportions to symptoms among a population of workers. A major problem is in maintaining good employee-employer communication while investigation and attempts at remediation take place. Health professionals will usually require expert environmental consultation to assist in the evaluation and remediation of identified outbreaks.

Multiple chemical sensitivities is a more problematic condition to define than sick building syndrome. Some organized medical entities, including the American Medical Association, have published position papers which question the scientific basis of the diagnosis of this condition. Many physicians who practise without a rigorous scientific basis have nevertheless championed the validity of this diagnosis. They rely on unproven or over-interpreted diagnostic tests such as lymphocyte activation or brain imaging and may recommend treatments such as sauna therapies and megadoses of vitamins, practices which have in large part engendered the animosity of groups such as the American Medical Association. However, no one denies that there is a group of patients who present with complaints of becoming symptomatic in response to low levels of ambient chemicals. Their constitutional symptoms overlap those of other subjective syndromes such as chronic fatigue syndrome and fibromyalgia. These symptoms include pain, fatigue and confusion, they worsen with low-level chemical exposure and they are reported to be present in a substantial percentage of patients who have been diagnosed with these other syndromes. Of great import, but still unresolved, is the question whether chemical sensitivity symptoms are acquired (and to what extent) because of a preceding chemical overexposure, or whether—as in the commonly reported situation—they arise without a major identified precipitating event.

Multiple chemical sensitivities is sometimes invoked as an outcome in certain sick building syndrome outbreaks which are not resolved or ameliorated after routine investigation and remediation. Here it is clear that MCS afflicts an individual or small number of people, rarely a population; it is the effect on a population that may even be a criterion for the sick building syndrome by some definitions. MCS seems to be endemic in populations, whereas sick building syndrome is often epidemic; however, preliminary investigations suggest that some degree of chemical sensitivity (and chronic fatigue) may occur in outbreaks, as was found among American veterans of the Persian Gulf conflict. The controlled exposure studies which have done much to clarify the role of volatile organic compounds and irritants in sick building syndrome have yet to be performed in a controlled manner for multiple chemical sensitivities.

Many practitioners claim to recognize MCS when they see it, but there is no agreed-upon definition. It may well be included as a condition which “overlaps” other non-occupational syndromes such as chronic fatigue syndrome, fibromyalgia, somatization disorder and others. Sorting out its relationship to both psychiatric diagnoses and to early reports suggests that when the onset of the syndrome is fairly definable, there is a much lower rate of diagnosable psychiatric co-morbidity (Fiedler et al. 1996). The phenomenon of odor-triggered symptoms is distinctive, but clearly not unique, and the extent to which this is an occupational condition at all is debated. This is important because Dr. Cullen’s (1987) definition, like many others, describes multiple chemical sensitivities as a sequel to a better-characterized occupational or environmental disorder. However, as stated above, symptoms following exposure to ambient levels of odorants are common among individuals both with and without clinical diagnoses, and it may be just as important to explore the similarities between MCS and other conditions as to define the differences (Kipen et al. 1995; Buchwald and Garrity 1994).

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