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.

Posterior atlas arch anomalies are relatively common, but have a variety of presentations ranging from partial clefts to complete agenesis of the posterior arch. Partial clefts are prevalent in 4% of patients and are generally asymptomatic. However, complete agenesis of the posterior arch is extremely rare. We report the case of a 46-year-old man who presented with upper cervical spine and occipital pain as well as left sided headaches. Imaging revealed congenital complete absence of the posterior arch of C1 (Type E) without any radiographic evidence of instability. We discuss our case in light of other reported cases and detail its management.

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