Chromosome studies on women formerly employed as luminous-dial painters.

In man the study of the harmful effects in bone of internally deposited radioactive material has been made either on subjects who have been given radium compounds internally for medicinal purposes, a practice now discontinued, or on subjects who have accidentally ingested-radium, and sometimes mesothorium, while working as luminous-dial painters. The use of self-luminous paints for watch dials developed in Germany and Switzerland before the first world war and followed the discovery that scintillations of light were produced by individual alpha-particles impinging on a screen of zinc sulphide. Self-luminous paints were made by mixing radium sulphate with zinc sulphide, and sometimes mesothorium was added to the mixture. During and immediately after the first world war increasing use was made of luminous paints, and from about 1925 reports based on the experience of early American dial-painters led to the recognition of the serious consequences that could follow the accidental ingestion of these compounds. There have also been a number of reports of the hazards associated with the internal use of radium compounds for medicinal purposes. It is clear that the accumulation in the body-over a short period of time of large amounts of radium or mesothorium leads to the early production of extensive bone damage with pathological fractures, to septic necrosis of the mandible and maxilla, and in many instances to the later development of bone tumours. Severe anaemia and leucopenia are also features of the acute and subacute forms of poisoning with radium or mesothorium, as originally reported by Martland, Conlon, and Knef (1925) and Martland (1929) from studies of the dial-painters who had worked in New Jersey. In the United Kingdom luminizing has been carried on continuously since the 1914-18 war period, and reached a peak, in terms of workers employed, during the second world war. At the beginning of the 1939-45 war it was realized that the luminizing industry would be considerably expanded during wartime, and, in view of the serious sequelae known to have occurred among early American workers, the occupation of luminizing was brought under the official supervision of the Ministry of Labour. In addition to laying down regulations designed to protect the worker against excessive radiation, this supervision took the form of periodic clinical and blood examinations , together with the maintenance of a careful watch for any symptoms that might be related to radiation exposure. British dial-painters, both before and after the introduction of …