ULTRA-VIOLET RADIATIONS IN CONDITIONS OF EXTREhlE CALCIUM AND PHOSPHORUS DEFIClENCY

Definite research for the causative factors in the nutritional disturbance known as rickets was begun by various observations as to its distribution and occurrence. In 1890 T. A. Palm (1) showed by a geographical survey that lack of sunlight seemed to be one of the chief factors in the causation of rickets. This led to the use of the sun bath in the treatment of rachitic children. In 1914 Rollier also mentioned rickets as amenable to sunlight therapy but did not discuss the possible role played by ultra-violet rays in calcium metabolism. Later the work of Finsen demonstrated that the portion of sun light spectrum of greatest therapeutic value lay in the ultraviolet zone. Hess (2) in 1918 demonstrated that the prevalence of rickets in the negro race could be accounted for in part at least by the factor of diet, as well as the role of fat-soluble vitamin and its relation to rickets. McCollum (3) and others demonstrated that rickets can be produced in animals if fed on a diet containing an excess of calcium but deficient in phorphorus and vice versa. It is now established by the work of many investigators that there are four factors: calcium, phosphorus, vitamin D and light rays, lack of any one of which plays an important part in the production of rickets. More recent studies of McCollum and Huldschinsky (4) the have shown prophylaxis that and ultra-violet treatment rays from of rickets. artificial It has sources are of value in been definitely shown that rickets ultra-violet can be prevented in animals if they are routinely exposed to radiation, while being fed on a diet unbalanced in calciumphosphorus content, but otherwise adequate for growth. Our present problem is to present additional evidence in confirmation of the previous findings, using a dietary somewhat more deficient in calcium and phosphorus than that used in previous experimental work. Former observations had demonstrated that the diet was below the optimum in phosphorus and calcium. Our problem was to determine if the radiations from the air-cooled mercury vapor lamp were sufficient to prevent rickets in rats fed solely on this deficient diet. A distance of 36 inches was selected for radiation, since the work of Hess and Weinstock (5) and other observers