Self-Reported Chemical Exposures at Onset and Symptom Provocation in Adults with Multiple Chemical Sensitivity: A Descriptive Cross-Sectional Survey

Multiple chemical sensitivity (MCS) is a chronic condition characterized by adverse reactions to low-level environmental chemicals, often resulting in multisystem symptoms triggered by volatile organic compounds (VOCs) emitted from fragranced personal care and household products. The condition raises public health and accessibility concerns, as people with MCS may face barriers to accessing workplaces, healthcare settings, educational institutions, and other public environments. This descriptive cross-sectional study aimed to characterize the chemical exposures participants attributed to the onset of MCS and to subsequent symptom provocation, and to describe the associated symptom patterns. A cross-sectional survey was administered to Canadian residents aged 18 years or older, living with MCS for at least 1 year, with 18 questions assessing exposure history and onset of MCS and symptom provocation. A total of 119 participants completed the survey. Participants most frequently attributed the onset of MCS to the workplace (55%) or home (35%), with (61%) reporting ongoing exposures over time as the most frequently reported circumstance associated with onset. Fragranced products, including perfumes, air fresheners, cleaning products, disinfectants, construction materials, and laundry products, were the exposures most frequently reported in relation to both onset and subsequent symptom triggering. Symptoms involved multiple organ systems, with nearly one-third of participants reporting 11 or more symptoms; cognitive and respiratory symptoms were most prevalent. Nearly three-quarters of participants (74%) reported symptoms associated with third-hand exposure, and 51% reported discarding contaminated items, suggesting that third-hand exposure may represent an underrecognized pathway for symptom provocation.