• Multiple chemical sensitivity involves sensitivity to low concentrations of various chemicals; however, its existence has not been scientifically confirmed.

Multiple chemical sensitivity (MCS) refers to a condition in which a person is considered to be sensitive to a number of chemicals at very low concentrations. It is often discussed in relation to indoor air quality (IAQ).

Symptoms of MCS involve more than one organ and seem to be brought on by exposure to very low levels of chemicals. Some symptoms include fatigue, loss of concentration, depression, and joint and muscle pain. However, no physical signs have been found consistently in MCS patients.

Stimuli that are believed to bring on the effects include pesticides, paints, adhesives, carpets and carpet cleaning materials, fragrances in perfumes and personal hygiene products, molds and fungi, petroleum products, electromagnetic fields, dental fillings, trauma, and industrial chemicals. Odors are often thought to be triggers.

Employers are responsible for helping employees who complain about symptoms that seem to come from the air. They have to find ways to accommodate complainants and work with them to help alleviate the symptoms.

MCS may affect a small percentage of the population and is not currently recognized by the major medical organizations. Medical opinion is divided, however, and further research is needed.

Proposed theories to explain the cause of MCS include allergy, dysfunction of the immune system, neurobiological sensitization, and various psychological theories. There is insufficient scientific evidence to confirm a relationship between any of these possible causes and symptoms. Due to the lack of definite information, an evaluation must be performed by a physician knowledgeable of the symptoms of this condition.