Multiple chemical sensitivity (MCS)


Multiple chemical sensitivity (MCS) describes an allergy-like reaction or sensitivity to chemicals. Patients who have MCS experience symptoms, including headache, skin rash, dizziness, and nausea, after exposure to chemicals that most healthy individuals can tolerate. Symptoms may develop after exposure to chemicals from products, such as perfumes, gasoline, smoke, or chlorine.
The duration of exposure and quantity of the chemical that can elicit a reaction varies among patients. MCS may occur if a patient was exposed to high levels of toxins from a chemical spill. It may also occur after long-term contact with low-levels of chemicals, which may be present in an office with poor ventilation. If chemicals from inside a building appear to be causing the symptoms, the condition is often called sick building syndrome.
Several organizations, including the American Academy of Allergy and Immunology, the American Medical Association, the California Medical Association, the American College of Physicians, and the International Society of Regulatory Toxicology and Pharmacology, do not recognize MCS has an established disease. This is because a clear relationship between chemical exposure and symptoms has not been established. Even though symptoms develop after exposure to chemicals, researchers have not discovered how the chemicals trigger the reaction. It has been suggested that MCS may be an allergic or toxic reaction to chemicals, but there is no evidence to support either of these claims.
Some researchers believe that symptoms are caused by psychological factors rather than physiological factors. It has been reported that 50% of patients with symptoms of MCS meet the criteria for having anxiety or depressive disorders. However, it remains unclear whether these psychological disorders are simply associated with MCS or whether they cause the condition. Studies are being conducted to determine the pathology of the disease.
Despite limited information about the disease, MCS is considered a valid condition for workmen's compensation claims, liability, tort, and regulatory actions.
MCS appears to be most common among patients who are 30-50 years old. According to the U.S. Environmental Protection Agency (EPA), about one-third of individuals who work inside buildings claim to be sensitive to one or more common chemicals.
Since little is known about MCS, specific treatments are unknown. However, symptoms generally subside once the patient avoids exposure to known chemical irritants. Patients can minimize exposure by purchasing hypoallergenic products. Patients who have sick building syndrome should talk to their colleagues and/or bosses to find ways to improve ventilation in the building.

Related Terms

Allergen, allergic, allergic reaction, allergic response, annoyance reactions, anxiety, carbon monoxide, cigarette smoke, chemical irritants, chemical spill, chemicals, chlorine, depression, depressive disorder, formaldehyde, hypersensitive, hypersensitivity, immune hypersensitivity, indoor allergens, intoxication syndrome, irritational syndrome, limbic system, pollutants, TILT, toxic-induced loss of tolerance, toxins.

other types of chemical sensitivities

Annoyance reactions: Annoyance reactions occur when the patient is overly sensitive to unpleasant odors. Some patients are born with this sensitivity, while others become sensitive after they develop an infection, abuse tobacco, overuse nasal decongestants, or after the lining of the nose becomes inflamed.
Immune hypersensitivity (allergic reaction): An immune hypersensitivity is an allergic reaction to chemicals. This occurs when the body's immune system overreacts to chemicals that enter the body. The white blood cells launch an attack against chemicals because they are mistaken for harmful invaders, such as bacteria or viruses. This reaction causes allergy symptoms, such as hives, skin rash, and headache, to develop. Allergic reactions usually occur in response to chemicals that are found in pollens, dust mites, and molds. Only a few industrial chemicals, which are used to produce consumer goods, have been shown to cause an allergic reaction. Examples include acid anhydrides and isocyanates.
Intoxication syndrome: Intoxication syndrome is the most severe type of reaction to chemicals. This typically occurs after long-term exposure to harmful chemicals, which may be present in pesticides, cleaning fluids, or paints. Intoxication syndrome is not an allergic reaction because it does not involve the immune system. Intoxication syndrome may cause a serious illness, which may lead to death in some patients.
Irritational syndromes: Irritational syndromes may occur after a patient is exposed to significant amounts of irritating chemicals. These chemicals may affect nerves in the body involved with physical sensations. As a result, patients with irritational syndromes often experience burning sensations in the nose, eyes, and throat after exposure to certain chemicals. Symptoms usually come and go, and they do not cause permanent damage.

common triggers

General: Multiple chemical sensitivity (MCS) may occur after exposed to high levels of toxins from a chemical spill. It may also occur after long-term contact with low-levels of chemicals that may be present in an office with poor ventilation. If chemicals from inside a building appear to be causing the symptoms, the condition is often called sick building syndrome. Areas of poor ventilation increase the number of chemicals and irritants in the air.
Buildings: Sick building syndrome occurs most often in new buildings that are designed to be energy-efficient, have windows that do not open, and have poor ventilation. These buildings often have high levels of carbon dioxide, which is a frequent cause of sick building syndrome. Chemicals found in renovation supplies, cleaning agents, and office machinery may also cause the reaction.
Cigarette smoke: Cigarette smoke is one of the most common causes of MCS. The smoke from cigarettes contains many chemicals, irritants, and gases, including formaldehyde, nacrolein, polycyclic aromatic hydrocarbons, hydrogen cyanide, carbon monoxide, nitrogen dioxide, and acrolein. Exposure to smoke indoors or in areas of poor ventilation significantly increases the amount of chemicals and toxins in the air.
Formaldehyde: Formaldehyde, which is also present in cigarette smoke, is present in gasoline and diesel combustion as well. Individuals are often exposed to these chemicals when they are waiting in traffic, especially if the windows are rolled down.
Wood-burning stoves: A gas called carbon monoxide is released into the air when wood is burned. When wood is burned during cold temperatures (e.g. fireplaces during the winter months), the amount of carbon monoxide released into the air increases. Also, poorly ventilated stoves release carbon monoxide, nitrogen, sulfur oxides, formaldehyde, and benzopyrene. All of these chemicals can potentially trigger a reaction in MCS patients.
Other: Other common triggers include perfume, nail polish remover, newspaper ink, hairspray, paint or paint thinner, insecticides, artificial colors, artificial sweeteners, food preservatives, adhesive tape, new carpets, flame retardants on clothing and furniture (such as mattresses), felt tip pens, chlorine in swimming pools, as well as chemicals from dust, pollens, animal dander, and molds.