A Report on Multiple Chemical Sensitivity (MCS)

The Interagency Workgroup on
Multiple Chemical Sensitivity


August 24, 1998

Predecisional Draft

Agency for Toxic Substances and Disease Registry

Department of Defense

Department of Energy

Department of Veterans Affairs

National Center for Environmental Health, CDC

National Institute of Environmental Health Sciences, NIH

National Institute for Occupational Safety and Health, CDC

U.S. Environmental Protection Agency

Summary of Federal Actions

Table of Contents

VIII. Federal Actions

The following statements have been prepared by each of the agencies represented in the workgroup. They describe their past and current activities related to low-level chemical sensitivity research and any future initiatives. It is hoped that these overviews will help in coordinating plans and further actions. The presentations also show the range of federal activities with regard to MCS.

Agency for Toxic Substances and Disease Registry

ATSDR, under its authorities in the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA), has maintained interest for several years in issues surrounding sensitivity to low levels of chemicals because these kinds of exposures can occur in populations who live near hazardous waste sites, which are the focus of CERCLA. Given the need for additional scientific research, ATSDR provided financial support for two conferences focused on MCS: the first meeting was sponsored by the National Academy of Sciences (NAS) in March 1991, and the second was sponsored by the Association of Occupational and Environmental Clinics (AOEC) in September 1991.

In fiscal year 1993, Congress appropriated $250,000 to ATSDR for "[c]hemical sensitivity and low-level chemical and environmental exposure workshops." The first effort under this mandate was to convene an expert panel in April 1993. Out of the deliberations of this panel came a number of recommendations that resulted in the following actions: (1) a conference on Low Level Exposure to Chemicals and Neurobiologic Sensitivity, Baltimore, Maryland, April 1994; (2) publication of the proceedings from that conference, as well as an additional publication containing the proceedings from three federally sponsored conferences on MCS (i.e., the NRC 1991, AOEC 1991, and ATSDR 1994 conferences); and (3) an award to the California Department of Health Services "[t]o develop a controlled, scientifically acceptable research design which will test the hypothesis that there is a group of individuals with physiologically based susceptibility to low levels of chemical exposure."

Throughout these efforts, ATSDR has served as a conduit of information about the issues surrounding MCS and has encouraged clinical and other research to add to the knowledge base concerning low-level chemical sensitivity. ATSDR has no on-going or planned research activities specific to MCS.

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Department of Defense

The Department of Defense (DoD) is sponsoring several projects with significance for better understanding multiple chemical sensitivity. Studies include investigation of the dysregulation of the normal neuroendocrine-mediated stress response which may lead to a better understanding of common underlying pathophysiologic mechanisms in fibromyalgia, chronic fatigue syndrome, multiple chemical sensitivity and the undiagnosed illnesses of Gulf War veterans. Another study is examining neuropsychological function in a group of treatment-seeking Gulf War veterans and non-deployed Gulf era veterans. One of the objectives of this study is to ascertain the prevalence of multiple chemical sensitivity-like symptoms reported among the male and female study population, and to explore risk factors for development of this condition.

DoD employees operate in unique work environments. The Department will continue to provide appropriate occupational health and industrial hygiene programs to minimize potential workplace exposures to hazardous chemicals. DoD will also continue to design and conduct essential health education, and provide safety equipment and engineering controls to minimize or eliminate exposures to known chemical and other workplace hazards. The Department's highest priority is to continue to provide a safe work environment for all DoD employees.

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Department of Energy

As the employer of more than 100,000 federal and contractor employees, the Department of Energy (DOE) is interested in developments in MCS. An informal sampling of the Department's occupational health clinics revealed occasions of workers complaining of possible MCS symptoms. Some of the clinic medical directors suggested that MCS may become a larger concern for DOE and would value guidance from the workgroup. There are currently no uniform diagnostic criteria or treatment protocols in use at DOE sites.

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Department of Veterans Affairs

The Department of Veterans Affairs (DVA) has funded three Environmental Hazards Centers for the purpose of conducting research on environmental health and toxicology related to military service. At this time, these centers are all involved in research on Persian Gulf veterans' illnesses. Two of the centers include research involving MCS in their research protocols.

At the Boston Environmental Hazards Center, the physical and psychological health of a cohort of Gulf War veterans has been followed longitudinally since their return from the Persian Gulf. A subset of these veterans is being examined intensively with protocols addressing MCS and other conditions; diagnoses of MCS, based on the Cullen criteria, are being made as appropriate. Detailed studies of those diagnosed with MCS include psychiatric status, neuropsychological function, symptom reports, occupational and economic outcomes, pulmonary function, neurologic status (central nervous system [CNS], peripheral nervous system [PNS], autonomic nervous system [ANS] with sophisticated neuroimaging and neuropsychological assessment), and evaluation of stressors (i.e., social, war trauma, and/or exposure to environmental hazards).

At the East Orange Environmental Hazards Center, an epidemiologic study of Persian Gulf Registry and nonregistry veterans is being conducted that will allow diagnosis of MCS, CFS, and other disorders. A cross-sectional study is being done of several categories of veterans: those with MCS but without CFS, those with CFS without MCS, and those having both CFS and MCS. Control subjects are being tested for viral/immunologic measures; psychiatric, psychological, and neuropsychological function, and autonomic deregulation. An experimental study is also planned at East Orange in which 40 MCS subjects will be exposed to two stressors (i.e., exercise and exposure to phenyl ethyl alcohol) and will undergo several preexposure and postexposure measures, including assessment of symptoms, neurobehavioral performance, nasal lavage cellularity, RNA levels of cytokine gene expression, and autonomic reactivity.

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National Center for Environmental Health, CDC

CDC's National Center for Environmental Health (NCEH) was established to promote health and quality of life by preventing and controlling disease, injury, and disability associated with the interactions between people and their environment outside the workplace. The impact of its programs is amplified through close interaction with public health departments in every state and with many public, private, and international organizations. Its major activities include biomonitoring for environmental toxicants, lead poisoning surveillance and prevention, birth defects surveillance and prevention, and exigent public health investigations where environmental exposures may be involved.

NCEH does not have any programs directly devoted to MCS; however, a number of its activities are relevant to the issues surrounding MCS. Through its division of Environmental Health Laboratory Sciences (EHLS), NCEH has a unique leadership role in measuring more than 200 toxicants in human biologic samples. Analyses of samples from large population studies have established the extent of exposure in the U.S. population to volatile organic compounds, pesticides, halogenated aromatic compounds (e.g., PCBs), toxic metals (e.g., lead and cadmium), and environmental tobacco smoke. This information helps to clarify relationships between exposures to toxicants and human health effects.

NCEH has also addressed the use of laboratory tests as biomarkers of susceptibility and health effects, concentrating on target organs such as the liver, kidney, and immune system. NCEH provides national reference laboratory capability for tests of immune status and function, including lymphocyte phenotyping, serum mediator measurements, and various assays of actual immune function. Standardization of these tests for immune status has been a particular focus at NCEH, whose investigators have collaborated with NAS, ATSDR, and AOEC to establish guidelines for the proper use of these tests and apply them to public health studies.

A number of epidemiologic investigations conducted by NCEH have relevance to questions of chemical sensitivities. Epidemiologists in the Division of Environmental Health Hazards and Health Effects have investigated adverse health effects associated with tryptophan ingestion, inhalation of fuels and other air pollutants, and fetal alcohol exposure. A community-based program in asthma prevention will explore risk factors and intervention effectiveness for this increasingly important cause of morbidity and mortality. At present, there is no specific funding or legislative mandate within NCEH in the area of MCS.

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National Institute of Environmental Health Sciences, NIH

The mission of NIH's NIEHS is to reduce the burden of human illness and dysfunction from environmental exposures by understanding the interrelationship between exposure, individual susceptibility, and time. NIEHS has provided research support to studies related to MCS and to areas of research associated with MCS outcomes.

Research activities funded by NIEHS related to chemical sensitivity focus primarily on (1) exposure and organ and system toxicology and (2) genetic susceptibility of exposure. It appears that environmental agents can trigger a variety of disorders in susceptible persons. Some susceptible persons apparently respond to extremely low levels of chemicals in the environment by expressing multiple symptoms in one or more organ systems, frequently involving the central nervous system. Such chemical exposures and symptoms appear to be associated with proximity to hazardous waste sites, other community exposures, indoor air pollution, and industrial activities. Pesticides and solvents are the two major classes of chemicals most frequently reported by patients reporting low level sensitivities as having initiated their problems.

NIEHS has also supported a number of workshops and meetings concerning MCS. In September 1995, the NIEHS Superfund Hazardous Substances Basic Research and Training Program supported a workshop in Princeton, New Jersey, entitled Multiple Chemical Sensitivities: Controlled Exposure Studies. This workshop brought together a number of leading investigators in the field to assist NIEHS in developing new and innovative research ideas to better understand MCS. The overall objective of the meeting was to develop experimental approaches for testing the relationship between chemical exposures and the symptomatology expressed by patients with chemical sensitivities.

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National Institute for Occupational Safety and Health, CDC

CDC's National Institute for Occupational Safety and Health (NIOSH) receives hundreds of requests annually for information on MCS. An estimated 200-400 requests are received through NIOSH's toll-free telephone number. NIOSH sends information about MCS to these requestors.

NIOSH conducts workplace health hazard evaluations at the request of workers, employers, and government agencies. A small number of requests have included mention of MCS in combination with a variety of other concerns.

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U.S. Environmental Protection Agency

EPA has occasionally received reports from individuals of symptoms that they attributed to chemical sensitivity subsequent to pesticide or other chemical exposures. Some EPA employees have also reported complaints of chemical sensitivity that they attributed to workplace or other exposures to various substances. EPA is interested in understanding the scientific basis for the development of effects following exposures at much lower levels than average, the exposures that produce such effects, and the quantitative relationships between them.

Research activities related to chemical sensitivity are being conducted by EPA as part of the agency's health research program on indoor air pollutants. EPA's statutory authority for indoor-air issues and problems enables the agency to engage in research and information dissemination rather than regulation, enforcement, or other control activities. In the indoor air health research program, research is being performed to (1) understand the relationship between exposure to and effects of selected biocontaminants; (2) develop methods and understand the risks posed by low levels and mixtures of indoor organic vapors; and (3) understand the dimensions and characteristics of susceptible populations, including those who report multiple chemical sensitivity. The goals of the research on susceptible populations are to identify such populations and evaluate the determinants of susceptibility, with current emphasis on clinically characterizing those persons who report having chemical sensitivity.

Part of the difficulty with conducting MCS research is identifying objective, quantifiable indicators for classifying research subjects in order to study their conditions in greater depth. An NAS workshop was initiated and funded by EPA's Indoor Air Division to identify research needs for MCS. Scientists from EPA's National Health and Environmental Effects Research Laboratory (NHEERL) also participated in the workshop, from which emerged a recommendation that careful clinical characterizations be done on persons reporting MCS to identify cases for additional study. In response to this recommendation, NHEERL scientists developed a protocol and initiated a pilot study to evaluate persons reporting MCS symptomatology on the basis of exposure history and symptoms; medical history and examination; psychiatric evaluation; and a profile of clinical medical, psychological, and physiologic parameters and test results. The purpose of this pilot study was to generate hypotheses that are feasible to test. Data were collected over an extended period of time on a small group of subjects who self-reported chemical sensitivity. NHEERL has not yet reported its findings.

In addition, EPA scientists are communicating and coordinating with other organizations involved in research on MCS. Besides cosponsoring and participating in the NAS workshop, EPA has coordinated with ATSDR to ensure mutual understanding of both agencies' efforts on MCS. NHEERL scientists have made invited presentations about MCS to the Toxicology Forum (Summer 1993) and the American College of Allergy and Immunology (Fall 1993). EPA participated in the ATSDR-sponsored MCS meetings held in 1993 and 1994. NHEERL is actively pursuing collaborative exchanges of information with investigators from the academic community (e.g., the University of Medicine and Dentistry of New Jersey and Yale University). NHEERL scientists have also published articles addressing MCS-related research issues (Dyer and Sexton, 1996; Dyer, 1997).

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Summary of Federal Actions

This section summarizes past and current MCS-related activities conducted by the departments and agencies that constituted the workgroup. As noted in Section VII, there were four recommendations that had support from four or more of the meetings described in that section. It is possible to relate the MCS-related activities with the workshop recommendations, as denoted below.

  • Conduct basic epidemiology—ATSDR funded the California MCS prevalence study; no other epidemiologic studies are currently being sponsored by the workgroup's agencies.
  • Conduct case-comparison studies—EPA scientists have developed a protocol and initiated a pilot study to evaluate persons reporting MCS symptomatology on the basis of exposure history and symptoms; medical history and examination; psychiatric evaluation; and a profile of clinical medical, psychological, and physiologic parameters and test results. The Department of Veterans Affairs is sponsoring research at three Environmental Hazard Centers; a subset of veterans of the Gulf War are being followed longitudinally for health and psychological symptoms using protocols that address MCS.
  • Develop a case definition for MCS—The workshops and meetings sponsored by the departments and agencies have all addressed various case definitions. No department or agency is expressly sponsoring an effort to develop a case definition for MCS.
  • Conduct challenge studies—No agencies of the workgroup are sponsoring or conducting these studies.

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