Reference Values for Hair Cotinine as a Biomarker of Active and Passive Smoking in Women of Reproductive Age, Pregnant Women, Children, and Neonates: Systematic Review and Meta-Analysis

Abstract:Exposure to environmental tobacco smoke (ETS) is most often estimated using questionnaires, but they are unreliable. Biomarkers can provide valid information on ETS exposure, the preferred biomarker being cotinine. However, no reference range of hair cotinine exists to distinguish among act