Chemical sensitivity is a physical reality that our society will have to recognize and address. The word "sensitivity" implies that tiny exposures lead to big problems. The 90,000 chemicals commonly circulating in our modern world appear to be causing considerably more problems for humans than are typically recognized. Chemically sensitive persons, when reacting to even small chemical exposures, suffer with various symptoms that range in intensity from being unpleasant to being temporarily or even permanently disabling. Only too frequently this condition is unrecognized as it progressively leads to poor health, reduced activity, stressed social relationships and reduced job productivity.

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Chemical sensitivity is a very real chronic medical condition that has been only slowly gaining the public recognition it deserves. Recent estimates suggest that chemical sensitivity, that is, hyperreactivity to various environmental agents (also known as incitants or triggers), may afflict something like 10-15% of the American population. Increasing awareness of this frequently annoying, often quite devastating and at times completely disabling illness has been due, in large part, to the efforts of environmental medicine practitioners, who have long appreciated the damaging impact - to both body and brain of certain highly susceptible individuals - of exposures to the myriad environmental toxins being manufactured at ever-increasing rates around the world.

It is believed that these chemically vulnerable modern-day "canaries in a coal mine" have an important lesson to teach us, if we would but listen - namely, that the hyperreactivity manifested by those with chemical sensitivity is an early warning sign of the alarming potential for eventual poisoning of our entire population by the numerous man-made chemical pollutants to which we are being continuously exposed. In other words, the fact that chemically sensitive individuals demonstrate exquisite vulnerability to toxic injury should serve to alert us to the disturbing reality that our modern industrial society, despite its many advantages, may ultimately compromise the health of us all.

Depending upon the severity of sensitivity, symptoms precipitated by exposures to toxic compounds can range from the subtle to the dramatic, the mild to the extreme. And any organ system in the body can be affected. The most common symptoms include headache, fatigue, weakness, muscle and joint pain, depression and irritability, anxiety and panic attacks, insomnia, dizziness, nausea, impaired memory and mental focus, difficulties breathing and swallowing, cough, gas and bloating, urinary frequency and urgency, visual disturbances, palpitations and chest pain, nasal congestion and sinus pressure, burning of the eyes and nose, and skin rashes.

Very sobering is the reality that certain man-made chemicals, like pesticides, were specifically designed to kill living things by poisoning their nervous systems. It should be no surprise that they wreak havoc on the brains of humans as well.

Common incitants include the following:

• Those substances widely recognized as toxic, e.g., the aforementioned pesticides; natural gas; petroleum-based solvents like toluene and benzene; volatile organic compounds (VOCs) like formaldehyde; heavy metals like mercury and aluminum; molds and the potentially dangerous mycotoxins they release; tobacco smoke; the phthalates and other endocrine-disrupting compounds, like bisphenol A, found in plastics; flame retardants like PBDEs; and automobile exhaust fumes;


• Those substances less often recognized as toxic, e.g., synthetic fragrances like perfumes, air fresheners, and other "pleasant-scented" products; newspaper print; personal care products; laundry detergents and fabric softeners; household cleaners; and fluoride-containing water and toothpaste; and


• More generally, the many pollutants found in the air we breathe, the water we drink, and the food we eat.

Sometimes sensitization develops because of a sudden, catastrophic exposure to a chemical pollutant; but sometimes it arises from the cumulative impact of repeated, low-dose exposures to chemicals over an extended period of time. Curiously, only certain individuals manifest obvious symptoms in response to these toxic exposures; others may be adversely affected on a subclinical level but manifest no overt symptomatology; still others may experience no ill effects whatsoever. We know that multiple factors (including genetic and environmental) contribute to the overall clinical outcome, but we do not yet fully understand either the underlying causes of sensitization to environmental toxins or why it is that some individuals develop chemical sensitivity and others appear not to.

Not surprisingly, however, we do know that sensitivity to low-level chemical exposures seems to be increasing at an alarming rate in our modern world. Over the past decade it has been estimated by various investigators that susceptibility to chemical exposures is becoming ever more pervasive and that the symptoms these exposures produce are becoming ever more crippling, resulting often in impaired work productivity and sometimes in job loss. A recent randomized population study conducted by Caress and Steinemann (Journal of Occupational and Environmental Medicine 2005;47(5):518-522) reported that 11.2% of those studied demonstrated a hypersensitivity to chemicals. Another randomized population study conducted by these same research scientists (Environmental Health Perspectives 2003;111(1):1490-1497) discovered that 1.8% of their entire sample not only manifested diminished work capacity but had lost their jobs because of their hypersensitivity to the chemicals to which they were being exposed in the workplace.

More generally, the scientific literature offers abundant support for the concept that the initial induction, and later triggering, of chronic health problems can occur as a result of chemical exposures. All the previously mentioned incitants (from pesticides to perfumes) can initiate a cascade of physiologic reactions that can devastate and disable individuals susceptible to sensitization from chemical injury. More generally, any environmental stressor (from infections to physical traumas to psychological stressors) can precipitate hyperreactivity in any of the regulatory organ systems in the individual's brain or body. It is extremely unfortunate that, despite the growing body of research literature in highly respected, peer-reviewed journals that demonstrates very clearly the physical/biochemical reality of both chemical toxicity and chemical sensitization, many persons in positions of authority remain unaware of the widespread prevalence and seriousness of environmental illness and are still oblivious to the adverse health effects of the multitude of man-made toxins contaminating our air, our water, and our food.

Early recognition of chemical sensitivity can spare affected individuals tremendous physical and mental distress and can prompt initiation of specialized treatments specifically designed to reduce the total body load of toxic pollutants and to replenish the total body reserves. Minimizing subsequent exposures, strengthening the body's nutrition, calming an over active immune system, and other supportive measures will afford considerable symptomatic relief and go a long way towards restoring quality of life to those afflicted with this unfortunate illness. Although such treatments do indeed help many with mild to moderate symptoms, there are some individuals who have been so seriously injured that (unable to work or even function on their own) they must rely for their very survival upon outside help to acquire "less toxic" water, food, and housing.

Even though most research scientists and clinical practitioners would agree that exposures to high levels of toxic chemicals will make most people sick, controversy arises when the exposures are to low levels of such chemicals. It should be recognized, however, that individuals who are susceptible to toxic injury (whether that susceptibility derive from genetic and/or environmental factors) may, after chronic exposure to low levels of toxins, become so sensitized that subsequent exposures to even tiny amounts of common chemicals not generally considered "toxic" will trigger a cascade of reactivity. In fact, an exposure to less than 1% of what would bother the "average" person may have devastating consequences for the chemically injured individual.

Whereas the fact of chemical sensitivity is indeed becoming an increasingly recognized reality, affected individuals may still find it difficult or even impossible to function in either a school or a work setting. Unfortunately, the concerns of students and workers who are affected by low-dose chemical exposures are not always taken seriously; such individuals may be criticized or even ostracized for giving voice to their concerns. Furthermore, they may be treated as if their condition were "all in their head." Although those with chemical sensitivity may also either have, or later develop, psychological difficulties, the consequences may well be tragic if "management" of the chemically susceptible patient considers only the psychological and not the physical.

A compounding factor in the evaluation of chemically susceptible patients is the fact that many such patients not only will look healthy but may also experience themselves as healthy. Appearances, however, can be deceptive, which makes it easy for practitioners to miss the diagnosis of chemical sensitivity. The seeming good health of such patients may actually be a result of the body's ability to adapt to environmental challenge by expending whatever resources it has available to return the system to a state of homeostatic balance - in which case, the body's adaptations will serve (temporarily) to mask the underlying sensitivities. Ultimately, however, the system's reserves will become depleted, overt symptoms of hyperreactivity to toxic exposures will develop as unmasking occurs, and the patient's health will begin to deteriorate. This highlights the importance of early detection and intervention to halt a downward spiraling of ever broader-based sensitization and compromised quality of life.

In truth, every effort must be made to reduce the patient's ongoing chemical exposures and to support the patient's self-healing capacities. If these corrective measures are not taken, the patient's health may well continue to deteriorate from continued exposures to everyday toxins.

Given the unfortunate reality of chemical sensitivity, the American Academy of Environmental Medicine (AAEM) offers the following:

1. We recognize the reality of chemical sensitivity as a primarily physical, not psychological, condition.
   
2. We espouse the treatment of chemically sensitive patients from a primarily physical, not psychological, perspective.
   
3. We support the education of healthcare professionals in the diagnosis and treatment of patients with chemical sensitivity.
   
4. To prevent induction, or subsequent triggering, of chemical sensitivity, we advocate the creation and maintenance of clean ("less polluted") environments in the home, the school, the work place, and the car.
   
5. We advocate the enforcement, by both public and private regulatory agencies, of fragrance-free classrooms, work sites, and other public places.
   
6. To that end, we believe that those people responsible for air, water, and food quality must be educated with respect to both the toxic and the sensitizing effects of environmental chemicals.
   
7. More generally, we support measures by both public and private agencies to do all within their power to reduce significantly the potential for toxic exposures to environmental chemicals.
   
8. We encourage academic institutions and public authorities to do all that they can to advance the public's awareness of this condition.
   
9. We advocate the creation of guidelines for the prevention, diagnosis, and treatment of chemical sensitivity.
   
10. We support continued research into the underlying causes, diagnosis, and treatment of chemical sensitivity.
    

For more than 40 years, the AAEM has been one of the few professional voices drawing attention to this problem of chemical sensitization. As a service to the healthcare community, the AAEM offers regular opportunities for formal training in Environmental Medicine; and, for those interested, we can provide an extensive bibliography of supporting medical research through our Central Office at AAEMonline.org.

The views expressed in this document are intended to be neither exhaustive nor conclusive. Our sincere and urgent hope is simply that more and more people in medicine, academia, government, and industry will come to understand and appreciate the very real issues of environmental toxicity and chemical sensitization.

(This statement was reviewed and approved by the Board of the American Academy of Environmental Medicine on October 29, 2008.)

Submitted by Philip Ranheim, M.D., who wishes to express his gratitude to Stephen Genuis and Larry Plumlee for suggestions offered during the initial phase of producing this paper and Jed Natzke, Jennifer Armstrong, Martha Stark, and Meg Sears for the many hours of hard creative work and serious editing required to create the final product.