REFERENCE DATA
SHEET FOR
MULTIPLE CHEMICAL SENSITIVITY
By: William D. Sheridan, CIH, CHMM
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INTRODUCTION MCS is often considered enigmatic, partially because of lack of clear
definition of the disease.7 A common basis of most definitions is that of a multi-symptomatic, multi-organ syndrome elicited in response to levels of chemicals, common foods, and/or drugs not eliciting such an effect in most people.8 Generally, duration and level of exposure are not consistent with the known toxicological properties of the chemical(s) involved in the exposure.9 In addition, there are no published, validated population estimates of the prevalence of MCS.10
The lack of clarity in definition of MCS has resulted in a division
of opinion within the medical community.11 The American College of Physicians published an extensive report on MCS and the related practice of clinical ecology in 1989. The College concluded that existing literature offered "inadequate support for the beliefs and practices of clinical ecology" and that diagnoses and treatments for MCS were ineffective. The American College of Occupational and Environmental Medicine endorsed this report. Position papers of the American Academy of Allergy and Immunology state there are no immunologic data to support the beliefs of the clinical ecologists. The American Medical Association (AMA) in 1991 concluded MCS should not be considered a recognized clinical syndrome. The AMA stated MCS proponents should prove any new tests in appropriately
controlled, peer-reviewed clinical trials rather than shifting the burden
to MCS critics to demonstrate effective therapies.12 These views contrast those of the clinical ecologists and other physicians represented by the American Academy of Environmental Medicine.13
IMPLICATIONS
PROPOSED DEFINITION Diagnosis and clinical management should include a detailed history
and comprehensive medical and psychosocial evaluation of the patient. Of
critical importance is to rule out the presence of a physical disease caused
by defined occupational or environmental factors (e.g., asthma, lead poisoning, allergic alveolitis, etc.).18,19
CAUSAL INFERENCE The following aspects of association have been used in the scientific
community to distinguish causal from noncausal associations (although general consensus exists that, other than temporality, there is no singly reliable criterion for determining whether an association is a causal association; all aspects of the association should be considered before deciding the most likely interpretation of the association is causation):
IMPLICATIONS Recommendations in the scientific community have stated that when
temporality is indicated, the dose response characteristics must be carefully evaluated. People should be made aware that odor detection does not ordain toxicity. The mere fact that the subject may have smelled the vapors does not establish toxic assault. In a situation in which a pre-existing condition (asthma) is similar to the claimed injury, establishment of causation from a subsequent chemical exposure may be virtually precluded. Alternative explanations for the possibility of cause for the alleged injury should be assessed.22
There is no established and widely available test to diagnose MCS.
Appropriate organ function tests, biological monitoring to specific chemical
substances, controlled challenge testing with suspected causative agents
(using placebos and double blinds), quantitative encephalography, immunologic testing, and neuropsychological testing have been recommended to rule out other illnesses in a differential diagnosis, but are subject to interpretation.23,24,25 Medications have been noted to include a wide spectrum of effects and may affect biological monitoring of industrial chemicals.26
ROLE OF INDUSTRIAL HYGIENE IMPLICATIONS Industrial hygienists may aid in such investigations by performing
a review of records (such as OSHA records, monitoring records, material
safety data sheets, safety inspection reports, and medical records) or
a facility inspection. The facility inspection may include interviews with
the facility management and other employees, a tour of the facility, an
assessment of the facility's ventilation systems, and assessment of operational parameters of the facility (e.g., the number of employees, the production levels, observation of work practices, etc.). Such reviews and inspections may reveal more detailed information regarding the nature of the chemical exposure(s) involved in assessing MCS. REFERENCES
In the 1950's, Dr. Theron Randolph first observed in a patient an effect he termed a "chemical susceptibility problem." Dr. Randolph then proposed the theory of extremely low-level chemical exposures adversely affecting an individual. A wide range of symptoms were attributed to the condition, and various therapeutic approaches were proposed.1,2 This observation has also been termed "environmental illness," "20th Century disease," "immune system dysregulation," "total allergy syndrome," "chemically acquired immunodeficiency syndrome," "cerebral allergy," "environmental maladaptation
syndrome," "food chemical sensitivity," and "multiple
chemical sensitivity (MCS)."3,4,5 In addition, MCS has symptomatology similar to that reported in "sick building syndrome."6
Difficulties are associated with MCS as a scientifically diagnosable disease. MCS requires definition as a disease and such definition requires consensus in the medical community. Epidemiological studies need to be well-constructed to assess the causal inference between exposure and disease. Clinical tests require control and should be based on sound scientific design to remove bias. Confounding issues, such as idiosyncratic response, dietary status, concurrent use of medications, and underlying disease need to be carefully assessed. The physiological mechanism for MCS, if one exists, must eventually be understood and confirmed by recognized scientific and medical studies published in peer-reviewed journals.14 Unfounded worker's compensation claims and toxic tort actions may have resulted from the conflicting ideas and incomplete information regarding MCS.15 Legislators and regulators may not be basing decisions regarding MCS on scientifically supported claims.16 Courts have held widely differing views in allowing traditional scientific evidence and expert testimony in MCS cases.17
Dr. Mark R. Cullen, a professor of medicine and epidemiology, has attempted
to define MCS, primarily for research purposes, and his is the most widely
used clinical definition. Cullen's definition consists of points including:
Causal relationships cannot be determined on the basis of anecdotal
reports alone due to difficulties in determining if a reaction is truly
associated with a described exposure. Some reactions may be caused by any
number of chemical exposures, such as foods consumed/dietary habits, genetics/idiosyncratic factors, concurrent use of medication, or by underlying disease. Confounding and bias may occur, and it is necessary to use the scientific method rigorously in assessing a disease such as MCS.20
As previously mentioned, there are no published, well-conducted epidemiological studies to provide statistical association between chemical exposure and MCS. The lack of clear definition of the disease itself has precluded collection of this data. Cullen's definition of MCS, if followed, could help to provide a more manageable definition to conduct such studies.
Industrial hygienists seek to prevent occupational disease and injury
through the anticipation, recognition, evaluation and control of environmental hazards found in the work environment. Industrial hygienists have been incorporated into occupational health settings as clinical consultants. This role includes:
Increasing interaction between occupational health professionals
may provide a general methodology for objectively conveying scientific
information in matters concerning MCS. In any case study, a review of medical records, in conjunction with an industrial hygiene inspection, exposure estimation, and literature review may offer a more likely causal factor for explaining the subject's symptoms. Although some criteria for causal inference is subjective, dose response information, limited statistical data, temporality, and the weight of experimental evidence may indicate a more likely cause for the symptoms.
This is not a Material Safety
Data Sheet but rather a Reference Data Sheet that has been compiled from a number of sources,
and is intended to be a concise, relatively non-technical source of information on a particular
material or category of materials. It is provided in good faith and is
believed to be correct as of the date compiled; however, Meridian Engineering & Technology
makes no representation as to the comprehensiveness or accuracy of the information. It is
expected that individuals receiving the information will exercise their independent judgement
in determining its appropriateness for a particular purpose. Accordingly, Meridian
Engineering & Technology will not be responsible for damages of any kind resulting from the
use of or reliance upon such information.