Chemical and Other Environmental Sensitivities

A variety of vague and hard-to-pinpoint symptoms are experienced by an undetermined, but possibly sizeable number of adults and children. Occasionally, they may suggest allergy or asthma, but most often the symptoms are much wider in scope.

Not much is currently known about what is referred to as "chemical sensitivity," but it is a subject that is often mentioned as a growing problem in the popular media. Since there are considered to be a variety of adverse health effects from so-called "chemical sensitivities," the public and their health care providers are rightly confused about what it is all about.

Why are Chemical Sensitivities Gaining so Much Interest?

There are several reasons, among which are:

• A greater number of complex chemical compounds (polymers) in our natural environment than in the past.

• Less indoor air exchange in more highly insulated houses and buildings.

• Greater media coverage of news and opinions about chemical sensitivities and their possible ill effects on our health.

A few physicians who refer to themselves as "ecologically oriented" have proposed diagnoses such as the "Twentieth Century Disease," "Chemical AIDS," "multiple chemical sensitivities," or "Candida hypersensitivity." Intriguing as these labels may be to some whose symptoms seem to frustrate the attempts of a medical diagnosis and treatment, no single test or combination of tests has yet to clearly identify the causes of these symptoms.

Nevertheless, caring physicians are sensitive to patients with vague complaints. They endeavor to keep them from seeking in desperation care and "cures" that lack a medical-scientific basis or require much more study.

What Are Considered Chemical Sensitivities?

There are four general ways that we can classify chemical sensitivity:

Annoyance Reactions. These result from a heightened sensitivity to unpleasant odors, called olfactory awareness, in some susceptible individuals. Your ability to cope with offensive—but mostly nonirritating—odors has a lot to do with genetic or acquired factors, among which are infection and inflammation of the mucous membranes or polyps (growths of the nasal or sinus membranes), and abuse of tobacco and nasal decongestants.

Irritational Syndromes. These are caused by significant exposure to irritating chemicals that are more likely than others to penetrate the mucous membranes. These types of reactions can affect certain nerve endings and cause burning sensations in the nose, eyes and throat. They usually come and go, and can be reversed.

Immune Hypersensitivity. This is the basis of allergic diseases, such as allergic rhinitis (hay fever) and asthma. They are generally caused by naturally occurring organic chemicals found in pollens, molds, dust and animals. At present, only a relatively few industrial chemicals are known to have the capability of provoking a true immune system response. Among them are acid anhydrides and isocyanates and other chemicals that are able to bond to human proteins.

Intoxication Syndrome. In some cases, long-term exposure to noxious chemicals may cause serious illness, or even death. Permanent damage to health may be the outcome of such reactions, which are dependent on the nature and extent of the chemical exposure. Toxic pollutants are given off by a number of building products, such as furniture, cleaning fluids, pesticides and paints.

How Does Pollution Affect My Health?

Most people who believe they have symptoms from chemical sensitivity are concerned that they are related to their exposure to pollution, either outdoors or indoors. Outdoor pollution may result from natural causes (the eruption of volcanoes, dust storms, forest fires), or man-made causes (vehicle exhaust, fossil fuel combustion, petroleum refining). Other pollutants that may cause respiratory illness include:

Sulfur Dioxide

Substantial scientific evidence has linked specific air pollutants to increased respiratory illness and decreased pulmonary function, especially in children. People prone to allergy, especially those with allergic asthma, can be extremely sensitive to inhaled sulfur dioxide, for example. Symptoms may include bronchospasm, hives, gastrointestinal disorders and inflammation of the blood vessels (vasculitis-related disorder).

Ozone and Nitrogen Dioxide

Temporary or perhaps permanent bronchial hypersensitivity has been connected to inhaled ozone and nitrogen dioxide. Long-term exposure to nitrogen dioxide has been associated with the increased occurrence of respiratory illness.

Significant exposure to airborne pollution occurs inside homes, offices and non-industrial buildings. These settings have not received nearly the attention by pollution control agencies that they deserve.

Cigarette Smoke

One of the most disagreeable and potentially dangerous indoor pollutants is cigarette smoke. It is made up of a complex mixture of gases and particles that contain numerous chemicals. Indoor tobacco smoking substantially increases levels of carbon monoxide, formaldehyde, nitrogen dioxide, acrolein, polycyclic aromatic hydrocarbons, hydrogen cyanide, and many other substances and inhaled particles found in the air.

Formaldehyde is not only found indoors from cigarette smoke, but also outdoors from gasoline and diesel combustion. Data indicates that formaldehyde is capable of acting as a respiratory irritant. It also is known to cause an allergic skin rash. However, there is no convincing evidence that this pollutant is able to sensitize the respiratory system.

Wood burning Stoves

There are more than 11 million wood burning units in American homes today. Wood burning usually occurs in cold, oxygen-poor conditions that heighten the emission of carbon monoxide and other inhaled chemicals and particles. Increased use of wood as a heating fuel has raised concern because of its ability to contaminate a home. Poorly ventilated stoves give off increased levels of carbon monoxide, nitrogen and sulfur oxides, formaldehyde and benzopyrene.

Building-related Illness

Poor air quality in today's tightly insulated homes and other buildings has been associated with a variety of syndromes, or group of symptoms. The term "building-related illness" or "sick-building syndrome" is applied to an office building in which one or more occupants develop a generally accepted, well-defined syndrome for which a specific cause related to the building is found.

There are a variety of illnesses broadly known as hypersensitivity pneumonitis—in which one or more organic dusts can create complex immune system reactions and symptoms, including mucous membrane irritation, coughing, chest tightness, headache and fatigue. These are well defined, and there are validated tests for diagnosing these conditions. Building occupants with these symptoms have been identified as having "multiple chemical sensitivities" or other forms of environmental illness.

One study, however, showed that the majority of nonspecific complaints by office workers had developed before the worker began working in the building suspected of causing their symptoms. Collaboration between the physician, industrial hygienist and building engineer may be necessary to clearly establish a cause-and-effect relationship between any indoor air quality level and disease.

How is Chemical Sensitivity Diagnosed?

There are strategies that can produce reliable diagnoses with relatively low costs, reliable diagnoses at significant costs or questionable diagnoses at great expense. Obviously, the first alternative is preferable. It includes:

• A careful patient medical history that includes a review of all previous medical records and, when symptoms may be related to potentially hazardous substances in the workplace, reviewing a Materials Safety Data Sheet supplied by the employer.

• Upper respiratory tract and selective skin tests and a neurological examination.

• Routine laboratory studies, including nasal smear.

• Lung function measurements (spirometry and peak flow monitoring).

If these diagnostic procedures do not produce a definite diagnosis, more expensive—but worthwhile—evaluations may help. They include an industrial hygiene evaluation of the workplace, an evaluation of the home environment and psychiatric evaluations.

Diagnostic approaches are expensive and not effective in explaining suggested chemical sensitivity such as the RAST test, and tests for the Epstein-Barr virus, auto-immune disease, food allergies, and evaluations to determine airborne molds and bacteria.

SOURCE: This information should not substitute for seeking responsible, professional medical care. First created 1995; fully updated 1998; most recently updated 2005.
© Asthma and Allergy Foundation of America (AAFA) Editorial Board