Multiple Chemical Sensitivies An Iatrogenically Perpetuated Disorder and Example of The Nocebo Effect

Modern Public Health Traces The Origin of multiple chemical sensitivities to Snow’s mapping of cholera cases and his subsequent removal of the handle of the Broad Street pump. Reducing the public’s exposure to environmental pollutants has long been a major role of public health practice. In earlier years pollutants were found to be biological pathogens and other toxicological substances of natural origin. In today’s in Industrialized societies, substances introduced by human activities have emerged as the natural contaminants have been brought under control. 

Abstract: “Multiple chemical sensitivities” (MCS) or “idiopathic environmental intolerances” (IEI) are diagnostic labels that have been given to patients with a variety of symptoms that they connect to chemical exposures. A small group of clinicians subscribe to the notion that these patients are being poisoned by low levels of chemicals. They transmit that belief to their patients, thereby perpetuating symptoms in response to chemical odors and perceived environmental threats. Their unfortunate role adds an iatrogenic component to their patients’ illnesses through the nocebo effect. This paper describes the clinical phenomenon of multiple chemical sensitivities, its likely causes, and examples of patients seen by one of the authors (R.E.G.) who have become disabled, in part due to the negative messages provided by physicians who view it as an organic disease.

Paradoxically, public health programs themselves have been accused of being the source of environmental contamination. Programs aimed at controlling mosquitoes, controlling insects that attack food crops or stored grains, weed abatement, water fluoridation, and the like have been the targets of actions by people who allege harm. However, unlike cholera or other biological pathogens, the putative harm caused by these public health programs is often very difficult to detect or prove. A field of pseudomedicine has arisen that claims to be able to diagnose and treat those who suffer from illnesses due to environmental contamination. For the purposes of this paper, we will focus on one of them, multiple chemical sensitivity disorder (MCS), which has been recently been termed idiopathic environmental intolerances (IEI). 

Defining MCS an Organic Floxicodynamic or Psychogenic Phenomenon? 

Multiple chemical sensitivities is a clinical phenomenon in which a patient experiences a wide variety of subjective symptoms in conjunction with low-level chemical exposures, either real or perceived.1 That such a phenomenon exists is undeniable. That individuals with such symptoms exist can be proven conclusively by merely asking them. Thus, the argument and debate surrounding MCS does not center on whether “it” exists but, rather, on what the “it” 

The MCS movement is driven by a zealous fervor to have MCS codified as an organic disease rather than a psychological phenomenon. Acrimonious debates center about this issue of cause. Is this perceived sensitivity to chemicals primarily a psychologically determined phenomenon or is it rooted in an actual interaction between the offending chemical and a structural body part? This issue is central to practitioners in the movement, activist organizations, and the entrepreneurs who profit from people’s fears. Why? Because a psychologically based disorder in which a sufferer merely “believes” that he or she is sensitive to chemicals will not be covered by workers’ compensation funds, cannot lead to successful lawsuits, and will not permit medical expenses to be paid by insurers. Moreover, it will not produce special accommodations for the sufferer, it will produce a different view of the sufferer by society and loved ones, and it will occasion an entirely different form of treatment. 

The diagnosis of MCS often begins a downward spiral of fruitless treatments, often culminating in withdrawal from society, condemning the sufferer to a life of misery and disability. This is a phenomenon in which the diagnosis is far more disabling than the symptoms. That is sad enough for adults, sadder still when children are involved, as many are. Yet rather than being dismissed as just another unusual belief, the concept of multiple chemical sensitivities has occasioned serious debate and spawned international medical conferences, programs sponsored by the National Academy of Sciences, innumerable articles in prestigious journals, and mainstream study in university medical centers.+!’ It has also gained increasing acceptance and recognition in our courts, legislature, regulatory agencies, and workers’ compensation commissions.12 

The Importance of The Physical Psychogenic Distinction

Dr. Mark Cullen from Yale University, who first employed the name “multiple chemical sensitivities,” has avoided taking a position on the question of cause and, in fact, argues that this issue of cause is irrelevant, for a sufferer is a sufferer regardless. 1•13 In fact, this is not true. It is true that one who suffers from the belief that chemicals are causing illness and one who suffers from an actual physical response to a chemical are both sufferers requiring care and deserving our compassion and understanding. Yet, those divergent causes generate entirely different remedies: most critically treatment, as well as legal, public policy, compensation, and workplace modification.’! We believe, therefore, that such distinctions are essential to proper clinical practice and rational societal response. 

Newer concepts of mind-body relationships suggest that clear distinctions between psychogenic and organic disorders are not readily made. We know, of course, that mood, feelings, stressors, fears, and worries can have profound impacts upon symptom development and even disease. This has led to a current trend to consider the mind and body as integrated rather than as functionally separate. While this argument does have some merit, it does not eliminate the need to identify the primary or predominant etiologic factors, whether they be emotional or organic. Every psychogenic symptom can also have a physical cause. Headaches may be caused by depression or by a brain tumor. Dizziness may be associated with anxiety or a middle ear infection. Trouble concentrating may be a symptom of stress or of Alzheimer’s disease. Nausea, respiratory distress, palpitations, and fatigue are all symptoms either of organic disease or of psychogenic stimuli. (Table 1 presents a list of symptoms that can have either organic or psychogenic causes.) Determining whether the symptoms arise from dysfunctional organs or from mind-body relationships is neither trivial nor unnecessary. 

One would not manage a brain tumor with psychotropic drugs any more than one would treat stress-related headaches with neurosurgery. Dizziness due to a middle ear infection is managed with antibiotics; the same symptom caused by stage fright might be treated with anxiolytics and behavior modification. Proper treatment is dependent on proper categorization. 

Regulatory, legislative, judicial, and occupational control responses are also dependent upon the critical distinction between psychogenic and organic etiologies. If people are truly being poisoned by low levels of chemicals, a certain set of responses follows. If, on the other hand, MCS sufferers are symptomatic for emotional reasons, the response is entirely different. This is not, as MCS activists argue, because we have no compassion for behavioral or psychologically induced dysfunction. Rather, public policy and general societal response is necessarily tied to the cause. One cannot accommodate public places or workplaces to variable and unpredictable individual responses. It would be both unreasonable and impossible to expect regulatory agencies, legislative bodies, and the courts to attempt to prevent or to compensate for idiosyncratic reactions and experiences. On the other hand, certain disability programs, such as Social Security, may provide benefits notwithstanding the emotional versus organic etiology, if dis-ability can be shown. Thus, while many responses will depend upon this critical distinction, others may not. 


Recognized Examples of Physical and Emotional Causes of Identical Symptoms 

Symptom Physical Cause Emotional Cause 

Headache Meningioma Stress 

Palpitations Myocardiopathy Anxiety 

Fatigue Lymphoma Depression 

Dizziness Middle ear infection Height in acrophobic 

Nausea Ulcer disease Conditioned response 

to a smell 

Abdominal pain Pancreatic tumor Somatization reaction 

Paralysis Spinal cord injury Conversion reaction 

Psychological Aspects of MCS 

A recent article in the New England Journal of Medicine notes that, worldwide, depression often manifests itself primarily with somatic symptoms.14 Others have written about depression as one of the psychological underpinnings of MCS. MCS patients form a heterogeneous group with a variety of psychiatric diagnoses and psychodynamic causes. These causes include panic attacks, 17•18 conditioned response, 19·21 chemical agoraphobia,8 and childhood trauma.22 Whatever the specific diagnosis or underlying cause, it is clear that a common thread of somatization is found in all these patients. 

The term “somatization disorder” describes a recognized psychiatric syndrome characterized by multiple organ system complaints without identifiable physical causes. The age of onset is, by definition, before thirty years.23 

Somatization, by contrast, is not a specific disorder. Rather, it is an endpoint, a set of symptoms arising from a wide variety of emotional factors. 23·24 Somatization may be a manifestation of depression, anxiety disorders, phobias, or various other life stressors. It may also be the expression of a subconscious troubled by early life events, such as child abuse.25·26 Somatization can have a mild endpoint, for example, occasional gastrointestinal distress; or somatization may be severe and disabling. 

Media Influence

Recent research indicates that somatization appears to be increasing.27·28 The authors cite the rise in “functional somatic syndromes,” such as “chronic fatigue syndrome, total allergy syndrome, food hypersensitivity, reactive hypoglycemia, systemic yeast infection, Gulf War syndrome, fibromyalgia, sick building syndrome, and mitral valve prolapse.” (Note: Total allergy syndrome is a synonym for multiple chemical sensitivities.) It is noted that while the medical bases of these syndromes remains unclear, they are portrayed by the media as major public health problems. Such publicity fosters self-diagnosis. 

There is currently a deluge of coverage of medical or medically related issues in the mass media, especially on television. It seems that every week brings with it another cause to champion, another population of sufferers in desperate need of the immediate attention of medical science. The medicalization of popular culture has not been devoid of positive consequences: The degree of celebrity and media attention to the AIDS epidemic made possible an enormous amount of funding that sped up the development of drugs such as AZT and the protease inhibitors. By contrast, trivial, unproven, and unlikely health threats also garner media attention. While putatively toxic carpets, sick buildings, toxic dental amalgams, and the supposed ill effects of exposure to computer monitor screens may be portrayed as hazards, in comparison to AIDS they remain both minor and unproven. Furthermore, a continual barrage of reports of environmental dangers engenders worry and primes sus-ceptible individuals to associate symptoms with environmental exposures. 

The Nocebo Effect  and Iatrogenesis

Though the nocebo effect was first described by Western medicine in the 1960s, its roots in other cultures extend back much further. 29 Anthropologists have described such phenomena as “voodoo death,” deaths believed caused by black magic, sorcery, and the like. 29 The power of the mind-body relationship is undeniable, and a patient’s expectations can have dramatic influences on clinical outcomes. Hence the present need for double-blinded placebo-controlled studies in order to achieve scientific legitimacy. Though there has been far more study of placebo effect, the nocebo effect can be just as deleterious to a patient’s health as the placebo effect is beneficial.30-34 

The nocebo effect, by creating negative expectations on the part of the patient, creates harmful effects that impair a patient’s clinical well-being.29 As in the placebo effect, the doctor alone does not usually create a nocebo phenomenon. Type A personalities (on the Bortner Rating Scale) and those who exhibit aggressive, competitive behavior are more likely to exhibit a nocebo response than their more placid, Type B counterparts.35 However, doctors rarely evaluate the personality types of their patients; rather, physicians can only hope to provide care that does no harm. 

A story is told about a doctor who was examining a patient with cancer. She asked the doctor, “Do I have a male cancer or a female cancer?” When asked by the doctor why she was inquiring about the gender of the cancer the patient replied, “Because I have heard that male cancers hurt much worse.” The doctor said to her, “You have a female cancer.”31 

Without directly posing the ethical question of whether it was “right” for the doctor not to disabuse the patient regarding the gender of malignant neoplasms, this story is illustrative of three important points. First, the patient looked to the doctor to tell her whether she would have a very painful cancer or a less severe form. Second, the ability of the doctor to influence the patient’s perceptions of illness are entrenched in the doctor-patient relationship. Third, by choosing to reply, “You have a female cancer” rather than saying that cancers have no gender or, sadistically, that the patient had a male cancer, the doctor decided that the most benign response was preferable to the truth for this patient. 

Sadly, not all clinicians faced with such situations act on the best interests of the patients. This is particularly so in the case of patients complaining of environmental sensitivities. Whether they are motivated by sheer greed or are actually deluded into believing scientifically incredulous theories, MCS physicians are routinely harming these “chemically sensitive” patients by confirming their false beliefs.36-37 These patients are often among the most susceptible to suggestion and are primed for confirmation that their symptoms are “genuine,” that is, not “all in their heads.” What follows is a series of case reports demonstrating how physician-induced nocebo effects may lead to iatrogenic chemical avoidance and its attendant disability. 

Case Reports

Cases 1-3 

Three women were working in a newly constructed day care center when they noted the intermittent and very brief smell of sewer gas. In fact, there had been an improper connection between the sewer exhaust and stack so that some sewer gas was released into the stack. At the time they smelled this they felt burning in their eyes and noses. They claimed that they were nauseated but did not vomit. About two weeks later one developed what she thought was a bad cold, characterized by pharyngitis and hoarseness. At approximately the same time, her two colleagues also had upper respiratory infections, which persisted and which they believed were related to chemicals in the school. Their physicians told them that they had either sinusitis, which could be treated with antibiotics, or other upper respiratory infections. Within a couple weeks of noting the sewer gas smell, the connection to the vent was repaired. The patients, however, had persistent respiratory infections, which they believed had something to do with chemicals associated with the odor. Sampling data provided no evidence of hydrogen sulfide or other chemicals. Because they perceived inattention from school officials, the three contacted an attorney, who sent them to a university medical center occupational medical clinic. They all described sinus problems, some depression, and some symptoms that they believed were odor related. They were diagnosed as having multiple chemical sensitivities (MCS) and were told that this was an incurable disorder and there was nothing that this medical group had to offer them. Consequently, they all found their way to an “alternative” MCS practitioner who claimed to be able to help them with sauna treatments, a variety of megavitamins, and avoidance of all chemicals. 

By the time they were seen by one of the authors, they were all wearing masks. All avoided leaving their homes for fear of developing an “attack,” and when they did go out they experienced dizziness, hyperventilation, tingling in the extremities, and severe anxiety. Thus they were, at this point, significantly disabled. 

On physical and laboratory examination, they were found to be entirely normal. The diagnosis in all cases was panic attacks, iatrogenically induced. 


A school was undergoing renovation. During the school year the school was in disarray and there was a white powder (ammonium phosphate from a fire extinguisher discharge) in one of the rooms. There were rare smells associated with carpet laying and painting. There was also one instance in which some diesel exhaust infiltrated the school and necessitated an evacuation. No abnormalities (including evidence of carbon monoxide toxicity) were identified. One of the teachers, chronically depressed with significant family problems, had a variety of symptoms, which she connected to the workplace. These included headaches, rashes, memory changes, muscle aching, painful joints, and tightness of her chest. Except for a single diagnosis of sinusitis, treated successfully with antibiotics, she had no clinical findings. Extensive testing of the school identified no elevated levels of mold, volatile organic chemicals, or any other problematic environmental agents. Later in the school year, a physician practitioner of chemical sensitivities and a “sick school” activist gave a lecture at the school and explained how and why the school would be expected to make everybody ill and sensitive to various other chemicals. This teacher was then referred to a similar practitioner who ordered a wide array of nonconventional tests and told her that her immune system was destroyed and that she could not be exposed to any chemicals in the future. 

By the time one of the authors examined her, her symptom complex had expanded and she largely avoided leaving her home for fear of chemical exposures and as-sociated symptoms. Her examination was essentially normal except for obvious depression. Diagnoses included depression with associated somatoform symptomatology and iatrogenic agoraphobia and chemical sensitivities. 

Case 5 

A 40-year-old woman had her home treated with an organophosphate pesticide. When she returned home 10 hours later there remained some residual odor from the petroleum-based diluent. The odor caused her to feel nauseated and to develop a headache. She moved into a motel for the night. When she returned home she again developed a headache and nausea, although the odor had dissipated. She saw her physician who tested her for organophosphate toxicity (negative) and found no abnormal physical or laboratory findings. She again attempted to return home, but each time she felt ill. At a friend’s house she explored the Internet discussions of pesticide poisoning and learned about multiple chemical sensitivities and physicians who specialized in that field. She went to one in a different state, who told her that she had been poisoned and elicited, through leading questions, reports of a wide variety of symptoms associated with various perceived chemical exposures. He told her that her immune system was damaged, gave her sauna treatments and megavitamins, and told her to avoid all chemical exposures. 

By the time one of the authors saw her she was significantly dysfunctional and never left her home without a respirator, bottled oxygen, and a full-body protective suit. She was clearly agoraphobic and iatrogenically dysfunctional. 


Physicians can powerfully influence patients’ perceptions and, therefore, their health. Reassurance can have a powerful placebo effect. Dire predictions and frightening diagnoses and terms such as “immune destruction,” “toxic responses,” and “permanent disability” do just the opposite. In fact, such nocebo suggestions become self-fulfilling prophecies, almost guaranteed to ensure dysfunction in all but the most emotionally resilient of patients. Moreover, most of the patients who seek advice of zealous MCS practitioners are not resilient. They are often emotionally fragile, primed to believe that their symptoms are toxicogenic and pleased to learn that they are not “all in their heads.” 

Thus, “alternative” MCS practitioners, unlike many other “alternative” practitioners who actually offer hope (placebo-based or not), offer little but a life of seclusion and a perpetuation of the sick role. Their impact, therefore, is far more pernicious than that of the majority of “alternative” practitioners. 


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