polonium and Leukemia--Radiation-Induced

The international incidence of myeloid leukaemia, cancer of the kidney, melanoma, and certain childhood cancers all show significant correlation with radon exposure in the home. For myeloid leukaemia, analysis suggests that in the UK 6-12% of incidence may be attributed to radon. In Cornwall, where radon levels are higher, the range is 23-43%. For the world average radon exposure of 50 Bq.m-3, 13-25% of myeloid leukaemia at all ages may be caused by radon.

Topics: Adult; Alpha Particles; Background Radiation; Bone Marrow; Canada; Child; Evaluation Studies as Topic; Fetus; Global Health; Humans; Incidence; Leukemia, Myeloid; Leukemia, Radiation-Induced; Neoplasms, Radiation-Induced; Polonium; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Radon; Regression Analysis; Risk Factors; United Kingdom

To assess increased exposure to airborne pollutants near power lines by investigating theoretically and experimentally the behaviour of 222Rn decay product marker aerosols in the 50 Hz electric field under power lines.. The behaviour of aerosols in outdoor air including those carrying 222Rn decay products was modelled theoretically in the presence of an AC field. TASTRAK alpha-particle spectroscopy was used to characterize 218Po and 214Po aerosols outdoors. Sampling points were chosen along a line at right angles up to 200 m from a number of high voltage power (transmission) lines. Each sampling point comprised an arrangement of mutually orthogonal TASTRAK detectors. Exposures were carried out at different power line locations in various weather conditions.. The model predicts a two- to three-fold increase in deposition of aerosols on spherical surfaces mimicking the human head under high voltage power lines. Experimental measurements using detectors mounted on grounded metal spheres showed an enhanced deposition of both 218Po and 214Po aerosols. Enhanced 218Po deposition on 400 kV lines ranged from 1.96+/-0.15 to 2.86+/-0.32. Enhanced 214Po deposition on 275 kV and 132 kV lines were 1.43+/-0.07 and 1.11+/-0.21, respectively, where the latter value was not significant.. The observations demonstrate a mode of increased exposure to pollutant aerosols under high voltage power lines by increased deposition on the body. The total (indoor + outdoor) 218Po and 214Po dose to the basal layer of facial skin is estimated to be increased by between 1.2 and 2.0 for 10% of time spent outdoors under high voltage power lines.

Topics: Aerosols; Air Pollutants, Radioactive; Atmosphere; Calibration; Child; Electromagnetic Fields; Environmental Exposure; Head; Humans; Leukemia, Radiation-Induced; Mathematical Computing; Models, Chemical; Polonium; Radiation Dosage; Radiation Monitoring; Radon; Radon Daughters; Spectrum Analysis

To estimate, under atmospheric conditions, 218Po deposition on a sphere representing the human head and compare with the effects of the maximum electric field to be found under a transmission line.. The effect of the wind in the absence of electric fields was calculated using the Reynolds Analogy between heat and mass transfer. The effect of the electric field was shown to be large compared with that of turbulence. A 'capture radius' due to the field was then estimated and charged 218Po particles blown into this region were assumed to be captured.. The deposition ratio was proportional to gammaV0.4E0(0.67), where gamma = charged fraction of 218Po, V = velocity and E0 = surface electric field. With the charged fraction ranging from 0.9% to 3.2%, a surface field on 280 kV m(-1) and a wind speed of 3 m s(-1), the deposition ratio ranged from 3.4 to 9.3. The surface field is several orders of magnitude higher than the average personal exposures that have been measured in epidemiological studies and the effect does not appear to be of epidemiological significance. At low velocities, the predictions of this model are in agreement with the measurements of Henshaw et al.. 218Po deposition by environmental AC fields cannot be advanced as an explanation for the reported associations between childhood leukaemia and electrical installations.

Topics: Atmosphere; Child; Electromagnetic Fields; Environmental Exposure; Head; Humans; Leukemia, Radiation-Induced; Mathematical Computing; Models, Chemical; Polonium; Wind