RELATIVE DISSOLUTION RATES OF RADIOACTIVE MATERIALS USED AT AWE.

A simple in vitro dissolution test was used to provide a semi-quantitative comparison of the relative dissolution rates of samples of radioactive materials used at Atomic Weapons Establishment in a lung fluid surrogate (Ringer's solution). A wide range of dissolution rates were observed for aged legacy actinides, freshly produced actinide alloys and actinides from waste management operations.

Assessment of uranium exposure from total activity and 234U:238U activity ratios in urine.

Radiation workers at Atomic Weapons Establishment (AWE) are monitored for uranium exposure by routine bioassay sampling (primarily urine sampling). However, the interpretation of uranium in urine and faecal results in terms of occupational intakes is difficult because of the presence of uranium due to intakes from environmental (dietary) sources. For uranium in urine data obtained using current analytical techniques at AWE, the mean, median and standard deviation of excreted uranium concentrations were 0.006, 0.002 and 0.012 µg per g creatinine, respectively. These values are consistent with what might be expected from local dietary intakes and the knowledge that occupational exposures at AWE are likely to be very low. However, some samples do exceed derived investigation levels (DILs), which have been set up taking account of the likely contribution from environmental sources. We investigate how the activity and isotopic composition of uranium in the diet affects the sensitivity of uranium in urine monitoring for occupational exposures. We conclude that DILs based on both total uranium in urine activity and also (234)U:(238)U ratios are useful given the likely variation in dietary contribution for AWE workers. Assuming a background excretion rate and that the enrichment of the likely exposure is known, it is possible to assess exposures using (234)U:(238)U ratios and/or total uranium activity. The health implications of internalised uranium, enriched to <5-8 % by mass (235)U, centre on its nephrotoxicity; the DILs for bioassay samples at AWE are an order of magnitude below the conservative recommendations made by the literature.

Clinical and economic effect of ciprofloxacin as an alternative to injectable antimicrobial therapy.

The effect of the use of oral ciprofloxacin on patient outcome and the cost of antimicrobial therapy was investigated. In 1988 ciprofloxacin was placed on the antimicrobial formulary at a Veterans Affairs medical center. Patients with urinary tract infections, soft tissue infections, osteomyelitis, or pneumonia due to organisms that were documented as being susceptible to ciprofloxacin and either resistant to other oral antimicrobials or susceptible to other oral antimicrobials in patients allergic to such agents were monitored in a prospective open study over 12 months. When a patient was enrolled, the physician was asked to select the i.v. antimicrobial regimen that would have been used if ciprofloxacin were not available. Patient outcome was determined from medical records, and the difference in the costs of the oral and i.v. regimens was calculated. Clinical cure occurred in 96/100 (96%) of patients with urinary tract infection, 19/22 (86%) with soft tissue infection, 14/16 (88%) with osteomyelitis, and 10/12 (83%) with pneumonia. The overall cure rate was 139/150 (93%). The 11 clinical failures occurred in patients infected with methicillin-resistant Staphylococcus aureus (MRSA) alone, group D enterococcus alone, MRSA and Pseudomonas sp., and Pseudomonas sp. alone. The total cost avoidance achieved by using oral ciprofloxacin instead of i.v. antimicrobials was $77,158. Oral ciprofloxacin was an effective and cost-efficient alternative to traditional i.v. antimicrobial therapy in the patients studied.