In memoriam: Thomas Mack, MD, MPH

Dr. Thomas Mack passed away Sunday, June 22, after a long illness. Tom was a giant in the field of epidemiology and public health and made seminal contributions to smallpox epidemiology and transmission, cancer cluster investigation, and causes of cancer and chronic disease, first as a CDC Epidemiologic Intelligence Service officer, then as a faculty member at the Harvard School of Public Health and finally at the USC Keck School of Medicine, where he was a Professor in the Department of Population and Public Health Sciences for 47 years. He was a driven scientist with a profound intellect and insatiable curiosity, and a warm and dynamic personality, a dry sense of humor and exacting standards for evaluating evidence before reaching conclusions about anything. He was fascinating and charismatic and inspired others to think deeply about whatever topics he was discussing, be it the latest movie, a political situation, or a scientific discovery.

Tom was born in Reno, Nevada on April 20, 1936, and raised on a ranch in Minden at the foot of the Sierra Nevada mountain range, a town of less than 200 people at the time, which instilled a life-long love of the natural world. He received a scholarship to Carleton College in Minnesota at 16 years old and left his small town to pursue a degree in biology with the thought of working for the U.S. Forest Service. Instead, he decided on medical school and attended Columbia College of Physicians and Surgeons in New York City. Here, he was exposed to and embraced multiple cultures and the wider world, over his career, visiting 51 countries, living in 4 and speaking over 5 languages. He was intensely interested in people and cultures and delighted in discussing the origins of even the most casual acquaintances. He was always interested in hearing stories of their lives, challenges, and accomplishments. He was a polymath who loved music, art, photography, movies, nature and above all, ethnic food which he sought out in every corner of his beloved Los Angeles.

His scientific accomplishments were many and left an indelible mark on the local, national and international public health field including early studies of smallpox transmission in East Pakistan (now Bangladesh) as a CDC officer, which laid the groundwork for the CDC/WHO vaccination strategy to eradicate smallpox. He founded the USC Cancer Surveillance Program to count cancer cases in Los Angeles County in 1974 (still active), and the International Twin Study and California Twin Program as a basis for impactful studies of causes of breast cancer, malignant melanoma, Hodgkin lymphoma, pancreatic cancer, multiple sclerosis and other chronic diseases. For example, he was one of the first to demonstrate that estrogen in hormone replacement therapy caused endometrial cancer (progesterone was later added to counteract this effect), that young adult Hodgkin lymphoma is highly heritable, and that early life exposure to sunlight is protective for multiple sclerosis. He was the Chair of the Carcinogen Identification Committee of California (Proposition 65) appointed by Gov. Pete Wilson and reappointed by all successive governors until he retired from the position in 2022. He published over 250 papers, received numerous grant awards from NIH including an Outstanding Investigator Award, authored two volumes of Cancers in the Urban Environment describing cancer patterns in Los Angeles County, was a co-author of WHO/IARC Cancer in Five Continents, and was an inspiring teacher and mentor to many students at every level. Tom leaves a great legacy as a leader and a colleague.

He will be sorely missed as a loving husband, father and grandfather and friend. He is survived by his wife Dr. Wendy Cozen, his daughters Christiane Mack and Alexandra Mack, grandchildren John Mack, McCulloch MacPherson, Isla MacPherson, Stepdaughters Molly Davis, Rose Surnow, Stepson in law Jay Davis, step grandsons Sy Davis and Benny Davis, nephew Brian Parks, niece Kristin Parks, and pre-deceased by his first wife Brita Mack, son Peter Mack, sister Maureen Mack and son-in-law Marko MacPherson.

In lieu of flowers, please make a donation to the Vaccine Integrity Project at the Center for Infectious Disease Research and Policy at the University of Minnesota (https://www.cidrap.umn.edu/support) or the Center for Biological Diversity (https://www.biologicaldiversity.org).