Do Patients with Complaints Attributed to Chemicals in the Environment Trust in Biomonitoring as a Valid Diagnostic Tool? A Prospective, Observational Study from a German University Outpatient Clinic

Biomonitoring often yields normal results in patients who report environmental sensitivities, such as in multiple chemical sensitivity. This study examined whether biomonitoring results influence disease attribution and perception. Patients over 18 presenting for the first time to the University Environmental Medicine Outpatient Clinic in Freiburg with suspected complaints linked to heavy metals, wood preservatives, pesticides, solvents, or mold spores were included. Illness perceptions were assessed before and after biomonitoring using the Illness Perception Questionnaire (IPQ-R). Of 358 patients, 51 met inclusion criteria; 3 showed relevant findings, and 15 did not attribute their symptoms to environmental causes at baseline. The remaining 33 patients were analyzed. After receiving a normal biomonitoring result, only seven patients (21%) altered their illness attribution. These individuals also reported milder perceived consequences, less personal control over the illness, and showed lower levels of somatization and compulsiveness than those who maintained their original attribution. Most patients remained convinced of an environmental cause despite unremarkable findings. This suggests that a substantial subset of patients is strongly attached to an environmental explanation for their symptoms, with stable attribution linked to higher psychological symptom burden and a belief in personal control over the illness.