Childhood cancer and residential proximity to power lines. UK Childhood Cancer Study Investigators.
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In the United Kingdom Childhood Cancer Study, a population-based case-control study covering the whole of England, Scotland and Wales, measured power-frequency magnetic fields were not found to be associated with risk for any malignancy. To examine further the risk associated with residential proximity to electricity supply equipment, distances to high-voltage lines, underground cables, substations and distribution circuits were collected for 3380 cases and 3390 controls. Magnetic field exposure from this equipment was calculated using distance, load and other circuit information. There was no evidence that either proximity to electrical installations or the magnetic field levels they produce in the UK is associated with increased risk of childhood leukaemia or any other cancer. Odds ratios of 0.73 (95% CI = 0.42-1.26) for acute lymphoblastic leukaemia, 0.75 (95% CI = 0.45-1.25) for all leukaemias, 1.08 (95% CI = 0.56-2.09) for central nervous system cancers and 0.92 (95% CI = 0.64-1.34) for all malignancies were obtained for residence within 50 m of an overhead line. When individuals with a calculated magnetic field exposure > or = 0.2 microT were compared to those in a reference category of exposure <0.1 microT, odds ratios of 0.51 (95% CI = 0.11-2.33) for acute lymphoblastic leukaemia, 0.41 (95% CI = 0. 09-1.87) for total leukaemia, 0.48 (95% CI =0.06-3.76) for central nervous system cancers and 0.62 (95% CI = 0.24-1.61) for all malignancies were obtained. (+info)
Results of a multisite study of U.S. residential magnetic fields.
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This paper describes the study design, measurement protocols, and results of a project examining residential magnetic-field exposures at eight sites across the contiguous United States. The goal of the project was to investigate surrogates that have been used in epidemiologic studies to characterize residential magnetic-field exposure. These surrogates include: personal-exposure (PE), fixed-location long-term (LT), and outside and inside point-in-time (PIT) magnetic-field measurements; net-service (or ground current) measurements; and the "wire-code category" of the residence. (The latter is a surrogate for magnetic-field exposure based on the nature and proximity of electric power lines outside the house.) Measurements were conducted on four visits to each of eight sites between January 1994 and June 1997 for a study population of 218 single-unit detached dwellings. Information on the residence, residents, and neighborhood was collected. A simple random sample of 392 single-unit detached dwellings at the sites was used to create a weighted sample of houses representative of the population of single-unit residences. The correlations among the various types of 60-Hz magnetic-field measures were relatively strong (Pearson r>0.74, Spearman rho>0.78). Variability of PE and LT measurements, as measured by the standard deviations during a visit, was independent of wire-code category. Visit means for PE, LT, and outside and inside PIT were well correlated over periods between visits of from 1.5 to 20 months (r>0.62, rho>0.76). These results support the use of survey measurements (less demanding than personal monitoring) to represent exposure that occurred up to 20 months in the past. The principal component of the total variance in PE measurements was the between-house variance; between-visit and between-site variances were generally less important. This supports the sampling of many houses with relatively few visits in residential exposure characterization studies. There was a trend for presumably higher wire-code categories to be associated with higher field summary measures for all summary measures related to magnetic-field magnitude, including PE and LT resultant, and inside and outside resultant (60 Hz) and harmonics. However, because of the overlap in field levels between categories, wire code was not a good predictor of magnetic-field levels, accounting for less than 21% of the variance in magnetic-field measurements. (+info)
Temperature measurement on neurological pulse generators during MR scans.
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According to manufacturers of both magnetic resonance imaging (MRI) machines, and implantable neurological pulse generators (IPGs), MRI is contraindicated for patients with IPGs. A major argument for this restriction is the risk to induce heat in the leads due to the electromagnetic field, which could be dangerous for the surrounding brain parenchyma. The temperature change on the surface of the case of an ITREL-III (Medtronic Inc., Minneapolis, MN) and the lead tip during MRI was determined. An anatomical realistic and a cubic phantom, filled with phantom material mimicking human tissue, and a typical lead configuration were used to imitate a patient who carries an IPG for deep brain stimulation. The measurements were performed in a 1.5 T and a 3.0 T MRI. 2.1 degrees C temperature increases at the lead tip uncovered the lead tip as the most critical part concerning heating problems in IPGs. Temperature increases in other locations were low compared to the one at the lead tip. The measured temperature increase of 2.1 degrees C can not be considered as harmful to the patient. Comparison with the results of other studies revealed the avoidance of loops as a practical method to reduce heating during MRI procedures. (+info)
Fire fatalities among children: an analysis across Philadelphia's census tracts.
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OBJECTIVE: This study investigates the possible causes of high levels of residential fire deaths to children younger than 15 years of age in Philadelphia from 1989 to 2000. METHODS: The authors analyzed 246 deaths from 146 residential fires by census tract in Philadelphia using both individual level data and aggregate level data drawn from the records of the Fire Marshall's Office. Death rates by age and sex were calculated using the 1990 Census. Data on fires from official records were combined with aggregate level data by census tract from the 1990 Census and analyzed using logistic regression. Newspaper articles on the fires analyzed were used to identify residences with possible fire code violations. The authors used data from the Philadelphia Bureau of Licenses and Inspections to provide evidence of code violations. RESULTS: The statistically significant variables that resulted from the logistic regression were census tracts in the highest quartile for low income households, census tracts in the highest quartile for single-parent households with children younger than age 18, census tracts in the highest quartile for houses built before 1939, and the number of children younger than 15 years of age in a census tract. CONCLUSION: Population characteristics by census tract are useful in identifying risk factors for residential fire deaths of children. Census tracts identified as at highest risk can provide fire prevention units with opportunities to take preventative measures such as the distribution of smoke detectors, and the education of residents about the dangers of careless smoking and planning for the rescue of children in the event of a fire. (+info)
Wire coding in the EMF and Breast Cancer on Long Island Study: relationship to magnetic fields.
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The Electromagnetic Fields and Breast Cancer on Long Island Study (EBCLIS) is a large population-based case-control study investigating possible associations between magnetic fields and breast cancer, and includes a comprehensive set of in-home measurements. We investigated the reproducibility of wire codes, their relation to 24-h measurements of residential magnetic fields, and potential influences, such as housing characteristics, in homes of the 1161 EBCLIS participants. Replicate wire coding was performed in homes originally categorized as having very high current configurations (VHCC) in the Wertheimer-Leeper (W-L) wire coding scheme, and a random sample of other homes (235 residences). Reproducibility was very high, with a kappa statistic of 0.83 (95% confidence interval (CI)=0.77-0.89) for the five-category W-L wire codes and 0.91 (95% CI=0.86-0.95) for the three-category Kaune-Savitz (K-S) codes. As levels of W-L and K-S wire codes increased, the mean and median 24-h levels of broadband and harmonic fields in the residences also increased, indicating an association between wire codes and magnetic fields measurements. Regions of Long Island with the highest percentage of homes built before 1950 had the highest percentage of higher current configuration homes, as well as the highest average 24-h broadband and harmonic measurements. Adjustment for age of the home and region did not affect the relation between wire codes and measured magnetic fields. Our results indicate that: (a). a high reproducibility in wire coding was achieved, (b). wire codes were correlated with magnetic fields, and (c). wire code levels were related to the age of the home. The high level of reproducibility suggests that, in our case-control analyses, there will be minimal bias due to misclassification of wire code categories. Results also suggest that wire codes are a proxy measure, to some degree, for current in-home magnetic field measurements in this study. (+info)
Residential magnetic field exposure and breast cancer risk: a nested case-control study from a multiethnic cohort in Los Angeles County, California.
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Some experimental and epidemiologic evidence suggests that residential exposure to power-frequency magnetic fields can increase breast cancer risk. This association was investigated in a nested case-control study of female breast cancer within a cohort of African Americans, Latinas, and Caucasians in Los Angeles County, California. Incident breast cancer was ascertained from 1993 to 1999 by linkage to county and state tumor registries. Controls were selected from a random sample of cohort members without breast cancer at baseline. Exposure was assessed in 1995-2001 by means of wiring configuration coding (an indirect measure of magnetic field exposure that has been associated with increased risk of childhood leukemia in Los Angeles and elsewhere in North America) in all homes occupied over the previous 10 years for 743 cases and 699 controls and by measurement of magnetic fields in the bedroom over a 7-day period for 347 cases and 286 controls. The estimated risk of breast cancer was not higher among women with wiring configuration codes associated with the highest magnetic fields (for a very high current configuration relative to very low, the adjusted odds ratio was 0.76 (95% confidence interval: 0.49, 1.18)). Stronger measured fields were not significantly associated with increased risk. These data suggest that residential magnetic field exposures commonly experienced by US women do not influence risk of breast cancer. (+info)
Risk of selected birth defects by maternal residence close to power lines during pregnancy.
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AIMS: To evaluate selected birth outcomes from a published Norwegian cohort study in a nested case-control design with improved exposure data. METHODS: Two controls matched for sex, year of birth, and municipality were selected randomly for children with the following defects: central nervous system (CNS) defects, cardiac defects, respiratory system defects, oesophageal defects, and clubfoot. The distances between maternal addresses, during pregnancy, and power lines were obtained from maps mainly of scale 1:5000. The magnetic fields in the residences were estimated based on distance, current, voltage, and configuration. RESULTS: The highest increased risks were seen for hydrocephalus (OR 1.73, 95% CI 0.26 to 11.64) and for cardiac defects (OR 1.54, 95% CI 0.89 to 2.68). CONCLUSION: This study does not support the hypothesis that residential exposure to electromagnetic fields from power lines causes any of the investigated outcomes. (+info)
Long-term follow-up of transvenous defibrillation leads: high incidence of fracture in coaxial polyurethane lead.
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BACKGROUND: As a result of longer follow-up after implantation of cardioverter defibrillators (ICD), fatigue of the leads has become a concern. The aim of this study was to determine the incidence and clinical presentation of ICD lead failures. METHODS AND RESULTS: The study population consisted of 241 patients with 249 ICD leads who underwent implantation of an ICD with a transvenous lead system. After device implantation, the patients were routinely followed up every 4 months. Five lead failures (2.0%) occurred as an oversensing of artifact during the follow-up period (2.6+/-2.1 years); 4 of those 5 patients received inappropriate shocks and 1 case of lead failure was identified in a patient with frequent episodes of non-sustained ventricular fibrillation. In particular, the right ventricular polyurethane transvenous lead in the Medtronic model 6936 failed in 4 (13%) of 31 cases. Percutaneous lead extraction was not available in all cases, so an additional ICD lead was inserted through the same site of the subclavian vein. CONCLUSIONS: Lead failures may occur 5 years after ICD implantation and polyurethane leads have an especially high incidence of failure. However, there were no follow-up parameters observed that predicted lead failures. (+info)