- The M.S. in Toxicology is a research-oriented degree requiring a minimum of 30 credit hours and a written thesis. At least 20 credit hours must be graduate-level courses. The program may include no more than 6 credit hours of research and no more than 2 credit hours of seminar. Courses at the 400 level counted towards the minimum 30-hour requirement may not come from the major field. All courses must be approved by the student’s advisory committee.