Letters Sent to Dr. Cecil K. Drinker, March 12, 1924

March 12, 1924. Dr. Cecil K. Drinker, c/o School of Public Health, Harvard University, 55 Van Dyke St., Boston, Mass. Dear Dr. Drinker:- Some days ago, Mr. J. A. Singmaster of the New Jersey Zine Company was good enough to call your attention to a problem that we have at our Plant. He informed me yesterday that the situation interests you and I am, therefore, sending you this brief sketch of the situstion. We manufacture phosthorescent zine sulphide that is used as a base for Undark radium luminous material. The fins. product is the zinc sulchide combined with vary small amounts of Radíum and Mesothorium. The radio-sctive element is measured in micrograms, the amounts varying in different grades of materials. Otherwise the material is the same. Undark powder sells for $1.00 to $10.00 per gram. I sm mentioning this since the price limits the amount of radio-active element that can be used. For a number of years, up until 191 9 or 1920, we maintained a large force of operators - girls - who applied Undark to watch dials, bands, and other articles. The process is atrictly a painting operation. The powder is mixed with tree gum adhesives and applied by hand with fine brushes. Some time ago, one of the operators developed a jaw condition which later became S. necrosis, and the young lady subsequently died. I am told that this could bs.ve been caused by phosphorus, tubercular infection, or other tooth condition. Ye use no phosphorus thatever in Undark. It is E highly purified zine sulphide and contains microscopic traces of impurities which make it phosphorescent. This is principally copper. Late last year, another operator developed a mouth condition which at first was thought to be similar. I understand, however, now that the girl is very much improved, indicating that the condition is not progressive in this instance. I have also been informed that her family have and considerable tubercular trouble. Those whom re have consulted can report nothing to us in the literature on these subjects that would indicate any form of poisoning from zine sulphide. Nevertheless, we must determine definitely and finally if there is any ingredient or if the material is any way harmful.