Validation of a screening instrument for multiple chemical sensitivity (MCS): the chemical odor sensitivity scale (COSS)

Multiple Chemical Sensitivity (MCS) -- also known as Idiopathic Environmental Intolerances (IEI) -- is defined as a disorder with multiple somatic and psychological symptoms attributed to low levels of various, chemically unrelated substances in the environment. Self-reported chemical odor sensitivity is an important feature of MCS. We describe the construction and the reliability and validity properties of a short questionnaire for the assessment of chemical odor sensitivity (COSS). The 11 items of the COSS were factor analytically derived from the Questionnaire of Chemical and General Environmental Sensitivity (CGES). Test statistical properties of the COSS were examined in college students, unselected community members, environmental medicine outpatients and chemically sensitive subjects. The COSS achieved good internal consistency in all samples (Cronbach's alpha = 0.89 - 0.93). Women and subjects from samples with higher MCS risk showed elevated COSS scores. The scale showed adequate construct validity and proved useful as an economic screening instrument for persons at risk for MCS.