Multiple Chemical Sensitivity (MCS) is a chronic medical condition characterized by symptoms that the affected person attributes to low-level chemical exposure. Commonly accused substances include smoke, pesticides, plastics, synthetic fabrics, scented products, petroleum products, and paint fumes. Symptoms are often vague and non-specific, such as nausea, fatigue, dizziness and headaches, but also commonly include inflammation of skin, joints, gastrointestinal tract and airways.
MCS is not recognized as an organic, chemical-caused illness by the American Medical Association and some other US based organisations. Blinded clinical trials have shown MCS patients react as often and as strongly to placebos, including clean air, as they do to the chemicals they say harm them. This has led some in the healthcare profession to believe MCS symptoms are due to odor hypersensitivity or are mainly psychological. Regardless of the etiology, some people with severe symptoms are disabled as a result.