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(Database last updated on Mar 27, 2024)
| ID Number | 1884 | |
| Study Type | Epidemiology | |
| Model | 60 Hz ELF exposure to residents near overhead power lines and correlation with childhood leukemia. | |
| Details | Children with acute lymphoblastic leukemia (n = 482) were evaluated for ELF exposure using personal 24-hour monitoring. The authors report the odds ratio associated with 5-yr relaps in children exposed to 0.3 microT (as compared with children exposed to less than 0.1 microT) was 1.9; 95% CI 0.8-4.9. The results were based upon only four deaths in 19 children. In a subsequent study, the authors investigated prognostic factors in this same childhood ALL population and could find no obvious trends between ELF exposure and adverse clinical or tumor specific prognostic factors or recurrent cytogenetic abnormalities in leukemic blast cells. As a possible mechanism to explain other observed correlations, the authors suggest coupling with metal water pipes and grounding by the earth may offer a possible explanation for increased exposures (due to field coupling and voltage running to the ground). The authors report that in several residential homes (n = 15), the environmental magnetic field levels correlated with voltage readings off water pipes and bathtub fixtures. The authors suggest that the relevant exposure in prior childhood leukemia studies may have been due to magnetic field induced contact current in the bathtub and not necessarily due to the magnetic field itself. The currents produced in the grounding system can also produce neutral-to-earth voltages that may (re-)produce new magnetic fields, all in some proportion to the overline magnetic field levels. Authors' abstract: Kavet et al. 2011 (IEEE #5120): It has been suggested that residential exposure to contact currents may be more directly associated with the potential for an increased risk of leukemia in childhood than magnetic fields. Contact current exposure occurs when a child contacts a bathtub's water fixtures, which are usually contiguous with a residence's electrical ground, and when the drainpipe is conductive. The Northern California Childhood Leukemia Study (NCCLS) is the only epidemiological study known to address whether contact current may confound the reported association between residential magnetic fields and childhood leukemia. The study contributed contact voltage and magnetic-field data for over 500 residences of leukemia cases and control children. We combined these data with the results of previous measurement studies of contact voltage in other communities to conduct an analysis of the relationship of magnetic fields with contact voltage for a total sample of 702 residences. The Spearman correlation of magnetic field with contact voltage was 0.29 (Spearman, P < 0.0001). Magnetic-field and contact voltage data were both divided into tertiles, with an upper magnetic-field cutpoint of 0.3 ¼T suggested by values used in epidemiological results and an upper contact voltage cutpoint of 60 mV based on dosimetric considerations. Expressed as an exposure odds ratios (EOR), we report an association of contact voltage with magnetic fields of 15.1 (95% CI 3.6-61) as well as a statistically significant positive trend across magnetic-field strata (EOR of 4.2 per stratum with 95% CI 2.4-7.4). The associations appear to be large enough to support the possibility that contact current could be responsible for the association of childhood leukemia with magnetic fields. AUTHORS' ABSTRACT: Kavet, Tell and Olsen 2014 (IEEE #5405): The process of setting science-based exposure standards (or guidelines) for radiofrequency (RF) contact current exposure has been disadvantaged by a lack of relevant data. The authors first review the essential features and results of the available studies and illustrate the apparent discrepancies among them. Then, they examine the manner in which current was administered in these studies and suggest as to how the physical relationship of a contacting finger to the current electrode may play a role in affecting sensory thresholds specific to those configurations. A major factor in this analysis relates to whether current density is uniformly distributed across the contact area or whether an electrode's 'edge effects' enhance currents with a net effect of decreasing apparent thresholds, when expressed as the bulk current entering a subject. For an exposure with a clear hazard potential, thresholds of human sensory response to RF currents require further investigation. AUTHORS' ABSTRACT: Kheifets et al. 2015 (IEEE #5995): We conducted a large epidemiologic case-control study in California to examine the association between childhood cancer risk and distance from the home address at birth to the nearest high-voltage overhead transmission line as a replication of the study of Draper et al. in the United Kingdom. We present a detailed description of the study design, methods of case ascertainment, control selection, exposure assessment and data analysis plan. A total of 5788 childhood leukemia cases and 3308 childhood central nervous system cancer cases (included for comparison) and matched controls were available for analysis. Birth and diagnosis addresses of cases and birth addresses of controls were geocoded. Distance from the home to nearby overhead transmission lines was ascertained on the basis of the electric power companies' geographic information system (GIS) databases, additional Google Earth aerial evaluation and site visits to selected residences. We evaluated distances to power lines up to 2000 m and included consideration of lower voltages (60-69 kV). Distance measures based on GIS and Google Earth evaluation showed close agreement (Pearson correlation >0.99). Our three-tiered approach to exposure assessment allowed us to achieve high specificity, which is crucial for studies of rare diseases with low exposure prevalence. |
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| Findings | No Effects | |
| Status | Completed With Publication | |
| Principal Investigator | Public Health Institute, Oakland, California - dfoliart@hospicecc.org | |
| Funding Agency | Private/Instit. | |
| Country | UNITED STATES | |
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