Input materials, products and by-products from a number of Florida phosphate mines and chemical plants were analyzed for '=Ra and 238U by high resolution gamma spectrometry. Concentrations were distinctly lower in North Florida than in Central Florida. In the matrix, the two nuclides were essentially in radioactive equilibrium (North Florida, 8 pCi/g; Central Florida, 38 pCi/g). Following beneficiation, concentrations in rock product, waste clays and sand tailings were approx. 100-300%, 100% and 10-25%, respectively, of those in the matrix. Radioactive equilibrium is markedly disrupted in phosphoric acid production; uranium follows the phosphoric acid while '=Ra appears in the by-product gypsum (North Florida, 14 pCi/g; Central Florida, 26 pCilg) and also in sediments and scales. Ammoniated phosphate fertilizers had relatively low levels of '=Ra but significant 238U (North Florida, 25 pCilg; Central Florida, 70 pcilg). On the other hand, triple superphosphate had significant concentrations of both (North Florida, 12 pCi/g; Central Florida, 20 pCilg) and u8U (North Florida, 26 pCi/g; Central Florida, 56 pcilg). In the electric furnace process, radioactivity is transferred to the slag (Central Florida, 61 pCilg of each nuclide). Within either region, nearly all sample types showed a considerable range of concentrations.

This paper reviews the data generated in studies of land radioactivity and indoor airborne radon progeny associated with mined and reclaimed phosphate lands in Florida. Highest indoor radon progeny levels are associated with the slab-on-grade type of construction. Concentrations exceeding 0.03 WL are associated with overburden soils, deposits and fill, while concentrations up to about 0.03 WL are associated with tailings. The lower limit for distinguishing increases above non-enhanced natural concentrations is on the order of 0.01-0.02 WL. Results of this study show that about 25% of the land produced by present methods of mining and reclamation practices would require restrictions on the type of construction or would require special construction methods. It is projected that with modification of mining and tailings disposal practices, virtually all of the land produced by mining and reclamation would be satisfactory for unrestricted construction use.

Florida beefwas sampled during May, 1966, and the first halfof 1967 and analyzed for 137Cs to help define the unusual radioecological situation first suggested by radionuclide levels observed in Florida milk. Cesium-I37 levels in grain-fed beef showed a geographic trend with the highest levels, 110-540 pCi/kg, occurring in the southern and south-central parts of the State and the lowest levels, 55-175 pCi/kg, occurring in the northwestern part. Levels in beef showed the same general geographic pattern shown by levels in milk.These findings and the results reported for Florida milk and dairy feeds indicate that this nuclide is concentrated to higher levels in biological materials in much of Florida than would be predicted from the distribution and levels of fallout deposition and from the average concentration by these media in other parts of the country.

Measurement of 137Cs body burdens in nearly 300 persons with the University of Florida whole-body counter from 1965 to date shows that Florida residents had levels of 137Cs two to three times as high as those reported elsewhere in the conterminous United States during the same time period. Analysis of the data by year shows that the levels did not drop with time as rapidly as levels reported in other areas of the United States.Cesium-137 levelsin Florida residents averaged 0.395,0.353, and0.318 nCi/kglean body mass in 1965, 1966 and 1967, respectively. For the entire 1965-1967 period these levels averaged 0.350 and had a range of 0.044-1.667nCi/kg lean body mass. In contrast, non-Florida residents measured at the same facility had an average of 0.151 nCi/kg lean body mass. Reproducibility of the measurements was within 10%.These levels correlate with the reported levels of 137Cs in Florida-produced foods, which in general are much higher than the average for the United States.