Stefan is currently Chief Science Officer of the American Botanical Council, an independent, nonprofit research and education organization. He is also technical director of the ABC-AHP-NCNPR Botanical Adulterants Program, a large-scale collaborative program initiated by the American Botanical Council (ABC), the American Herbal Pharmacopoeia (AHP), and the National Center for Natural Product Research (NCNPR) at the University of Mississippi to educate members of the herbal and dietary supplement industry about ingredient and product adulteration. Prior to working for ABC, Gafner served as a Director of Analytical Chemistry in the R&D department of natural personal care products company Tom’s of Maine.

Stefan received his degree in pharmacy at the School of Pharmacy, University of Berne, in Berne, Switzerland. He obtained a PhD in pharmaceutical sciences, with a focus on the chemistry of medicinal plants, from the University of Lausanne in Switzerland, and conducted postdoctoral research on cancer chemopreventive natural products at the University of Illinois – Chicago in the College of Pharmacy’s Department of Medicinal Chemistry and Pharmacognosy. Stefan is author or co-author of over 70 peer-reviewed scientific publications and holds 5 patents. He is a member of the advisory board of the Society for Medicinal Plant and Natural Product Research (GA) and of the editorial boards of the Journal of Ethnopharmacology and Planta Medica .