Prevalence of Multiple Chemical Sensitivity in Lebanon: A Cross-Sectional Study among the General Population Post Beirut Port Blast

Background: Multiple Chemical Sensitivity (MCS) is a complex and controversial syndrome characterized by heightened sensitivity to common chemicals, often resulting in debilitating symptoms affecting multiple organ systems. Growing evidence suggests that environmental pollutants, fragrances, and household chemicals contribute to MCS, making it a rising global public health concern. Despite this, no studies have assessed its prevalence in Lebanon, where large-scale chemical exposure occurred following the 2020 Beirut Port Blast. Objectives: To assess the prevalence of multiple chemical sensitivity (MCS) syndrome and hypersensitivity symptoms among the public community in Lebanon. Methods: This cross-sectional study involved 720 persons residing in 8 Lebanese provinces and investigated chemical sensitivity using the validated tools: Quick Environmental Exposure and Sensitivity Inventory (QEESI) and the Environmental Hypersensitivity Symptom Inventory (EHSI). Cross-tabulation and Chi-Square analyses were used to investigate the association between MCS scales and sociodemographic variables. Results: The study showed a prevalence of MCS represented by chemical intolerance (CI: 35.6%), other intolerance (OI: 18.2%), severity symptoms (SS: 34.9%) and masking index (MI: 43.9%). Female gender, older age (50 years old and above), residing in urban areas, history of clinical diagnoses, and an experience of MCS after Beirut Port Blast were positively associated with MCS scales (P < 0.05). Community-based interventions and clinical studies are recommended to raise the public awareness regarding the MCS and the implications of chemical exposure.