Jan O. Aaseth is a research adviser and professor at Innlandet Hospital & Inland Norway University of Applied Sciences. He is chair of the Nordic Trace Element Society and vice chair of the Committee for Geomedicine of The Norwegian Academy of Science. He graduated in medicine in 1968 from the University of Oslo. After the internship period, he became an authorized physician in 1970. In the period 1970–1977, he worked at the Department of Clinical Chemistry and Institute of Clinical Biochemistry, Oslo University Hospital, with a grant from the National Research Council. He completed his doctoral thesis on metal chelation in 1976, and became an authorized specialist in medical biochemistry. In the period 1977–1983, he continued his research on biochemical toxicology at the National Institute of Occupation Health of Norway. During this time he specialized in occupational medicine, and he chaired the Department of Experimental Toxicology for two years. After a subsequent period of specialization in internal medicine, he was appointed as chair and professor of the Department of Occupational Medicine, University of Tromsø, Norway. Later, he was head of the Department of Clinical Chemistry and Section on Endocrinology at Innlandet Hospital, and in recent years professor at Hedmark University College. His work is focused on endocrinology, nutrition and toxicology during all phases of life.