Maurice Goldhaber, who died in May 2011, shortly after his 100th birthday (PHYSICS TODAY, May 2011, page 40, and October 2011, page 65), was not only a great nuclear and particle physicist but also a witty and engaging speaker. Many years ago, when someone asked him if he was yet retired from Brookhaven National Laboratory, he said, “How can I be re-tired; I am not even tired yet.”

On the occasion of the 50th anniversary of his mentor James Chadwick’s 1932 discovery of the neutron, Goldhaber gave talks about the early days of nuclear physics. When he spoke at the University of Michigan, someone drew his attention to a radioactive toothpaste, named Doramad, that was produced in Germany from the 1920s to the 1940s. At a later talk I attended at Duke University, he showed a poster advertising Doramad. I told him that the toothpaste had been manufactured as a byproduct by the industrial firm Auergesellschaft near Berlin; my father, an organic chemist, worked there until our emigration from Nazi Germany in 1935. During my entire childhood I brushed my teeth with Doramad!

Naturally occurring thorium has a half-life of 14 billion years and emits 4-MeV alpha particles—a very mild activity. It was extracted by my father’s company from monazite sand, imported from India primarily as a source of rare-earth elements. Those rare-earth materials were used by the company’s founder, Austrian scientist Carl Auer von Welsbach, to impregnate the mantles in gas lanterns, so they would shine brightly, and for a number of other products, including tinted sunglasses and dyes. As one of the companies involved in the production of nuclear fuel for potential German weapons, the Auergesellschaft also figured in the report of the Alsos Mission, led by Goldhaber’s colleague Samuel Goudsmit. After the war, the company was taken over by Degussa.

The health benefits of Doramad were touted on the toothpaste tube: “Its radioactive radiation increases the defenses of teeth and gums. The cells are loaded with new life energy, the bacteria are hindered in their destroying effect. This explains the excellent prophylaxis and healing process with gingival diseases. It gently polishes the dental enamel so it turns white and shiny. Prevents dental calculus.”1 

Maurice Goldhaber never forgot that I grew up using radioactive toothpaste.