Saruhashi became the first woman to receive a Doctor of Science degree from the University of Tokyo, for her dissertation on carbonic matter in natural water.
On March 25, 1957, Katsuko Saruhashi received her Doctor of Science degree from the University of Tokyo, becoming the first woman ever to earn this degree from the prestigious institution.
Her dissertation, titled "The Behavior of Carbonic Matter in Natural Water," built directly on her earlier research establishing methods to measure dissolved carbon dioxide and related compounds in seawater. At the time, Japanese academia was overwhelmingly male-dominated, and women faced significant structural and cultural barriers to pursuing advanced degrees in the sciences.
Saruhashi's achievement was groundbreaking not only as a personal milestone but as a powerful symbol that shattered assumptions about women's capabilities in rigorous scientific research. It came at a time when Japan was still rebuilding its scientific institutions in the post-war period, and opportunities for women to reach the highest levels of academic science were exceedingly rare.
This accomplishment paved the way for her subsequent leadership roles, including her founding of the Society of Japanese Women Scientists just a year later. It also established her scientific authority, which she would leverage extensively in her later, more politically significant work on radioactive fallout, and cemented her legacy as a trailblazer for women in Japanese STEM fields.