Jacob “Joop” Willem Thiessen passed away on January 3, 2020 at the Immanuel Lutheran Home in Kalispell, Montana at the age of 91. He was born April 22,1928, in Hillegersberg, (presently City of Rotterdam), the Netherlands to Jacob Willem Thiessen and Suzanne Maria Thiessen. He was preceded in death by his parents and his sister, Margaret Thiessen Mulder. He is survived by two daughters, Suzanne L. Thiessen of Terschuur, the Netherlands, and Corinne M. Thiessen of Capelle aan den Ijssel, the Netherlands, his son, Diederik G. Thiessen of Bel Air, Maryland, and one grandson Ernst Lucas.
Joop Thiessen was raised in The Netherlands and was living there with his parents for the entire period when Germany occupied his native country during the 2nd World War.
He attended the University of Utrecht School of Medicine from1947 to1953 where he received his medical degree. After graduating, he served in the Royal Netherlands Army from 1953 to 1970. During that period, he performed post-doctoral studies in radiation pathology and dosimetry at the University of Leyden.
After completing his post-doctoral studies, Dr. Thiessen served as a consultant to the Surgeon General of the Netherlands Army and to the Netherlands’ National Health Council when environmental and health effects of radiation from above-ground nuclear testing were subjects of national concern. He was an expert on the metabolism and dosimetry of internally deposited radionuclides, and was intimately involved in the development for the Netherlands Government of standards for the protection of the population from food and water contaminated by radioactivity from above-ground nuclear testing.
In 1970, Joop Thiessen was invited to come to the U.S., where he served until 1976 as Medical Director of the Radiation Management Corporation, a consultant to the nuclear energy industry. In that position, he was involved in planning of the medical response to and management of nuclear accidents.
From 1976 to 1981, he was Director of Occupational and Environmental Health at the U.S. Army’s Environmental Hygiene Agency where he worked on medical aspects of the military use and disposal of radioactive materials and chemical warfare agents.
He served as Deputy Associate Director for Health and Environmental Research in the U.S. Department of Energy from 1981 to 1987 where he was involved in the funding and oversight of research on the health and environmental effects of energy technologies.
In 1987, he became Vice Chairman of the American/Japanese Radiation Effects Research Foundation in Hiroshima and Nagasaki, Japan, where he was intimately involved in medical follow-up studies of the atomic bomb survivors in Japan. He retired from that position in 1993, and moved to the Flathead Valley in Montana where he resided until his passing.
Joop Thiessen was Board Certified in Preventive Medicine (Occupational Medicine) and in Health Physics, a non-medical specialty. He was a Fellow of the American College of Preventive Medicine of the College of Physicians of Philadelphia. He was also, a Fellow of the Health Physics Society, Consociate Member of the National Council on Radiation Protection, and member of the Academy of Health Physics.
While living in Japan, he became a member of the Rotary Club of Nagasaki South, and upon return to the U.S., of the Rotary Club of Kalispell, Montana. He served as its President from 2006-2007, as Assistant Governor of District 5390 from 2007-2009, and then as Dean of the District Leadership Academy. He was the recipient of multiple Rotary awards, including the Rotary Foundation District Service Award, the Rotary ‘Service Above Self’ Award, the Rotarian Of The Year Award for 2007-2008, and the Rotary Lifetime Service Award in 2014. He was a Paul Harris Fellow of Rotary International. As a Rotarian, he was especially interested and involved in projects that provided medical equipment to communities in undeveloped countries.
Joop Thiessen was an avid reader throughout most of his life. He enjoyed symphony music and served on the Board of Directors of the Glacier Symphony. He was a firm believer in the application of reason and science to the solving of human problems, to the betterment of human life, and to the protection of our environment. His abounding optimism, generosity, and sense of humor will be missed by all who knew and enjoyed his company.
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