Multiple chemical sensitivity (MCS) and others: allergological, environmental and psychological investigations in individuals with indoor air related complaints.

Clinical observations point to an expanding group of individuals attributing hypersensitivity phenomena to indoor air pollution. It was the aim of this study to characterize such subjects by an interdisciplinary approach. Sixty-five individuals, recruited by a public campaign, were studied by a thorough allergological examination and a structured psychological interview. Measurements of common indoor pollutants in the air and in the dust were performed in rooms of several selected patients. Forty-two patients (65%) revealed a sensitization to common allergens, out of these 32 (49%) to house dust mites. Thirty-eight (58%) patients showed a psychosomatic or psychotic disorder. Increased concentrations of at least one of the measured indoor air pollutants were found in 11 out of 13 investigated houses. According to these results, four groups of patients could be identified: Seventeen patients (26%) had "classic" allergic diseases treated inadequately. In 19 patients (29%) allergic diseases were superimposed by strong psychosomatic interactions. An exclusive psychosomatic or psychotic cause of the complaints was found in 19 (29%). Ten subjects (16%) had "classic" allergic diseases (e.g. allergic rhinoconjunctivitis, urticaria), however, there were additional indications of hypersensitivity reactions to components other than classical allergens. Patients presenting with hypersensitivity phenomena attributed by themselves to indoor air pollution are a heterogeneous group and need a diligent work-up including intense allergological examination. The role of increased concentrations of indoor air pollutants has to be elucidated further.