RESUMEN
PURPOSE: To study geographical variations in the level of naturally occurring 210Pb-supported 210Po in permanent teeth of juveniles in the UK. MATERIALS AND METHODS: Permanent teeth extracted from 278 juveniles for orthodontic purposes were obtained from 48 counties in the UK. 210Po activity concentration was measured on the outer enamel surface using TASTRAK alpha-particle-sensitive plastic track detectors. RESULTS: Geometric mean +/- SE activity concentrations in teeth from urban, suburban and rural areas, excluding the high radon area of Devon, were 8.41 + 0.25/-0.24, 7.76 + 0.37/-0.35 and 7.20 +0.49/-0.46 Bq kg(-1), respectively. Overall, there was no significant association between alpha-activity on the outer enamel surface of permanent teeth and proximity to the major UK motorways. However, when the data were considered with respect to the prevailing south-westerly wind on the western side of the UK, a statistically significant association with respect to donors living downwind (on the easterly side) of the motorways was found. This effect was greater for sections of the M5 and M6 motorways that traverse urban areas. 210Po levels in teeth were also associated with domestic radon concentration. This effect was comparable with that from traffic and urban pollution. CONCLUSIONS: Higher levels of 210Pb-supported 210Po are seen in permanent teeth of juveniles near sources of increased exposure in the UK. Inhalation uptake is an important pathway of exposure, especially with respect to domestic radon exposure. The results might be important in assessing integrated exposure to 210Po in the skeleton and consequent high linear energy transfer dose to bone marrow.
Asunto(s)
Dentición Permanente , Exposición por Inhalación , Radioisótopos de Plomo/análisis , Polonio/análisis , Adolescente , Niño , Exposición a Riesgos Ambientales , Humanos , Efectos de la Radiación , Radón/análisis , Población Rural , Población Suburbana , Reino Unido , Población UrbanaRESUMEN
PURPOSE: To examine the microdistribution of natural alpha-radioactivity in deciduous teeth of children and the permanent teeth of juveniles extracted for orthodontic purpose from across the UK. MATERIALS AND METHODS: The microdistribution of 210Pb-supported 210Po and 226Ra in 708 deciduous and permanent teeth and 32 foetal teeth was measured on 1442 TASTRAK alpha-particle track detectors. RESULTS: Of the various findings, a number are of special interest. Around half of the 210Pb activity in the outer enamel of deciduous teeth appears to have been acquired in utero as a result of transplacental transfer. In deciduous and permanent teeth, 226Ra is concentrated mainly in the circumpulpal region, while the highest levels of 210Po are on the highly calcified outer enamel surface. Furthermore, activity concentrations recorded on this surface were In-normally distributed. CONCLUSIONS: 210Pb-supported 210Po activity on the outer enamel surface of permanent teeth constitutes an assay of cumulative environmental exposure with which to assess exposure in bone, both in utero and in childhood. Such assessment can be used to study geographical variations in the alpha-activity in teeth. More work is also required to determine the concentrations of both 210Po and 210Pb in the foetal skeleton.
Asunto(s)
Dentición Permanente , Exposición a Riesgos Ambientales , Diente Primario/efectos de la radiación , Adolescente , Adulto , Niño , Preescolar , Femenino , Humanos , Radioisótopos de Plomo/análisis , Masculino , Polonio/análisis , Efectos de la Radiación , Radio (Elemento)/análisis , Reino UnidoRESUMEN
PURPOSE: 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. MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.