Radon and lung cancer: a cost-effectiveness analysis.
OBJECTIVES: This study examined the cost-effectiveness of general and targeted strategies for residential radon testing and mitigation in the United States. METHODS: A decision-tree model was used to perform a cost-effectiveness analysis of preventing radon-associated deaths from lung cancer. RESULTS: For a radon threshold of 4 pCi/L, the estimated costs to prevent 1 lung cancer death are about $3 million (154 lung cancer deaths prevented), or $480,000 per life-year saved, based on universal radon screening and mitigation, and about $2 million (104 lung cancer deaths prevented), or $330,000 per life-year saved, if testing and mitigation are confined to geographic areas at high risk for radon exposure. For mitigation undertaken after a single screening test and after a second confirmatory test, the estimated costs are about $920,000 and $520,000, respectively, to prevent a lung cancer death with universal screening and $130,000 and $80,000 per life-year for high risk screening. The numbers of preventable lung cancer deaths are 811 and 527 for universal and targeted approaches, respectively. CONCLUSIONS: These data suggest possible alternatives to current recommendations. (+info
Radiation exposure from gallium-67-citrate patients.
OBJECTIVE: Serial monitoring of patients was performed to determine the radiation exposure contributed by patients injected with 67Ga-citrate to their surroundings. Radiology and nursing staff distance exposure estimates were made for various patient care tasks and imaging tests. METHODS: Fifteen adult patients were surveyed early (mean 4.3 min) and 11 of the 15 were surveyed at 3 d (mean 68.8 h) postinjection. The standard adult lymphoma imaging activity of 333-407 MBq (9-11 mCi) resulted in a range of 3.7-8.1 MBq/kg (0.1-0.22 mCi/kg). Dose rate measurements were made in the anterior, posterior, and left and right lateral projections at the level of the umbilicus, at distances of patient's surface and at 30.5 cm and 100 cm with a calibrated ion chamber. Time of contact-routine task analyses also were obtained for nursing and radiology personnel. Using a radiation survey-derived biexponential pharmacokinetic relationship, radiation exposures were determined for hospital personnel and family members at various times after injection. RESULTS: Based on the study population survey results, the mean instantaneous exposures (microSv/h) for an administered activity of 370 MBq (10 mCi) 67Ga-citrate were determined. The task analyses revealed the maximum patient contact time for any procedure performed at a distance equal to, or less than, 30.5 cm was 30 min. CONCLUSION: The quantitation of radiation exposure scenarios from 67Ga-citrate patients has determined that no special precautions are necessary for medical personnel when performing routine tasks associated with these patients. (+info
Residential exposure to electromagnetic fields and childhood leukaemia: a meta-analysis.
Although individual epidemiological investigations have suggested associations between residential exposure to electromagnetic fields (EMFs) and childhood leukaemia, overall the findings have been inconclusive. Several of these studies do, however, lend themselves to application of the meta-analysis technique. For this purpose we carried out searches using MEDLINE and other sources, and 14 case-control studies and one cohort study were identified and evaluated for epidemiological quality and included in the meta-analysis. Relative risk estimates were extracted from each of the studies and pooled. Separate meta-analyses were performed on the basis of the assessed EMF exposure (wiring configuration codes, distance to power distribution equipment, spot and 24-h measures of magnetic field strength (magnetic flux density) and calculated magnetic field). The meta-analysis based on wiring configuration codes yielded a pooled relative risk estimate of 1.46 (95% confidence interval (CI) = 1.05-2.04, P = 0.024) and for that for exposure to 24-h measurements of magnetic fields, 1.59 (95% CI = 1.14-2.22, P = 0.006), indicating a potential effect of residential EMF exposure on childhood leukaemia. In most cases, lower risk estimates were obtained by pooling high-quality studies than pooling low-quality studies. There appears to be a clear trend for more recent studies to be of higher quality. Enough evidence exists to conclude that dismissing concerns about residential EMFs and childhood leukaemia is unwarranted. Additional high-quality epidemiological studies incorporating comparable measures for both exposure and outcomes are, however, needed to confirm these findings and, should they prove to be true, the case options for minimizing exposure should be thoroughly investigated to provide definitive answers for policy-makers. (+info
Radiological states around the Kraton-4 underground nuclear explosion site in Sakha.
A radiological survey around the site of Kraton-4, an underground nuclear explosion (Yield of 20 kt, depth of 560 m, 1978) in Sakha was carried out in March 1998. Gamma survey and in-situ spectroscopy on the ground exhibited quite normal levels: a dose rate of 0.022 microSv/h and Cs-137 surface contamination of less than 1.1 kBq/m2 around the hypocenter. The results suggested no remarkable leakage of radioactivity from the epicenter to the ground surface at least not for non-rare gas elements as of 1998. (+info
Radioactive contamination of packing materials from a xenon-133 shipment.
OBJECTIVE: We report on radioactive contamination of packing materials from a 133Xe shipment. METHODS: A 2-vial 133Xe shipment was monitored using a survey meter before opening. Both vials were immediately assayed in a dose calibrator. The packing materials were monitored and contamination was detected. RESULTS: The maximum surface reading of the shipment was 7.0 microSv/h. This was higher than previous shipments (1.1 +/- 0.3 microSv/h). One vial was 544 MBq while the other vial was only 474 MBq. Previous shipments were 565 +/- 13 MBq/vial. Monitoring and imaging revealed 133Xe contamination within the packing materials. Xenon-133 escaped from the packing materials over time. The lower activity vial continued to leak 133Xe over time. CONCLUSION: Careful monitoring of 133Xe shipments before and after opening along with assaying vials on receipt can indicate vial leakage and radioactive contamination so steps can be taken to minimize radiation exposure to the staff. (+info
Cytogenetic monitoring of hospital workers occupationally exposed to ionizing radiation using the micronucleus centromere assay.
A cytogenetic study was performed in lymphocytes of hospital workers occupationally exposed to X- and gamma-rays using the micronucleus centromere assay. A comparison of the data for the exposed group and an age-matched group of non-exposed hospital workers showed a significant (P < 0.05) increase in centromere-positive micronuclei for the radiation workers, while no effect on centromere-negative micronuclei was present. The observed systematic increase in micronucleus frequency with age was mainly due to increased chromosome loss, reflected in the centromere-positivity of the micronuclei. The micronucleus frequencies were 40% higher in females than in males, which can again be attributed to higher chromosome loss. Two exposed individuals showed exceptionally high micronucleus yields, 90% of which were centromere-positive. In situ hybridization with a centromeric probe for chromosome X shows that X chromosome loss is responsible for these high micronucleus yields. In the studied population, smoking had no significant effect on the micronucleus yields. The results obtained indicate that in contrast to the predominantly clastogenic action of acute exposure to ionizing radiation, the aneugenic properties of radiation may be important after long-term chronic low dose exposure. (+info
Does the endovascular repair of aortoiliac aneurysms pose a radiation safety hazard to vascular surgeons?
OBJECTIVES: Endovascular aortoiliac aneurysm (EAIA) repair uses substantial fluoroscopic guidance that requires considerable radiation exposure. Doses were determined for a team of three vascular surgeons performing 47 consecutive EAIA repairs over a 1-year period to determine whether this exposure constitutes a radiation hazard. METHODS: Twenty-nine surgeon-made aortounifemoral devices and 18 bifurcated devices were used. Three surgeons wore dosimeters (1) on the waist, under a lead apron; (2) on the waist, outside a lead apron; (3) on the collar; and (4) on the left ring finger. Dosimeters were also placed around the operating table and room to evaluate the patient, other personnel, and ambient doses. Exposures were compared with standards of the International Commission on Radiological Protection (ICRP). RESULTS: Total fluoroscopy time was 30.9 hours (1852 minutes; mean, 39.4 minutes per case). Yearly total effective body doses for all surgeons (under lead) were below the 20 mSv/y occupational exposure limit of the ICRP. Outside lead doses for two surgeons approximated recommended limits. Lead aprons attenuated 85% to 91% of the dose. Ring doses and calculated eye doses were within the ICRP exposure limits. Patient skin doses averaged 360 mSv per case (range, 120-860 mSv). The ambient (> 3 m from the source) operating room dose was 1.06 mSv/y. CONCLUSIONS: Although the total effective body doses under lead fell within established ICRP occupational exposure limits, they are not negligible. Because radiation exposure is cumulative and endovascular procedures are becoming more common, individuals performing these procedures must carefully monitor their exposure. Our results indicate that a team of surgeons can perform 386 hours of fluoroscopy per year or 587 EAIA repairs per year and remain within occupational exposure limits. Individuals who perform these procedures should actively monitor their effective doses and educate personnel in methods for reducing exposure. (+info
Residential randon exposure and lung cancer risk in Misasa, Japan: a case-control study.
In order to investigate an association between residential radon exposure and risk of lung cancer, a case-control study was conducted in Misasa Town, Tottori Prefecture, Japan. The case series consisted of 28 people who had died of lung cancer in the years 1976-96 and 36 controls chosen randomly from the residents in 1976, matched by sex and year of birth. Individual residential radon concentrations were measured for 1 year with alpha track detectors. The average radon concentration was 46 Bq/m3 for cases and 51 Bq/m3 for controls. Compared to the level of 24 or less Bq/m3, the adjusted odds ratios of lung cancer associated with radon levels of 25-49, 50-99 and 100 or more Bq/m3, were 1.13 (95% confidence interval; 0.29-4.40), 1.23 (0.16-9.39) and 0.25 (0.03-2.33), respectively. None of the estimates showed statistical significance, due to small sample size. When the subjects were limited to only include residents of more than 30 years, the estimates did not change substantially. This study did not find that the risk pattern of lung cancer, possibly associated with residential radon exposure, in Misasa Town differed from patterns observed in other countries. (+info