 Unable to obtain a stipend, he was offered to reorient toward pharmacology and toxicology, which he did, earning his M.Sc.in 1956 and his Ph.D. in 1958.Plaa went to teach at Tulane University, then the University of Iowa, before in 1968 he was hired by Université de Montréal (UdeM) as Chairman of the Department of Pharmacology, a young promising scientist who the previous year had become the first recipient of the newly created Achievement Award of the American Society of Toxicology.