Power-Frequency Electric and Magnetic Fields and Risk of Childhood Leukemia in Canada

McBride, Mary L.; Gallagher, Richard P.; Thériault, Guylène; Armstrong, Ben; Tamaro, Sharon; Spinelli, John J.; Deadman, Jan-Erik; Fincham, Shirley; Robson, Dave; Choi, Won

doi:10.1093/oxfordjournals.aje.a009899

Cited by 203 publications

(168 citation statements)

References 16 publications

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“…We felt that if we could also incorporate new studies from non-European countries this pooled analysis would be up to date and presumably stay current for several years. We were aware of three more studies in other parts of the world with compatible information that were all nearly A pooled analysis of magnetic fields and childhood leukaemia completed or recently completed, so we could include those too (Linet et al, 1997;Dockerty et al, 1998Dockerty et al, , 1999McBride et al, 1999). Table 1 lists the studies and their relevant characteristics.…”

Section: Methodsmentioning

confidence: 99%

A pooled analysis of magnetic fields and childhood leukaemia

et al. 2000

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It is now twenty years since Wertheimer and Leeper (1979) published the first study suggesting an association between residential exposure to extremely low frequency magnetic fields (EMF) and childhood cancer. Ever since, this has been a controversial issue with the findings from several, but not all, subsequent epidemiological studies being consistent with an association, particularly with respect to residential exposure and childhood leukaemia (Portier and Wolfe, 1998). However, many of the reports have been based on small numbers of exposed cases, and despite intense experimental research no known biophysical mechanism to explain an effect has been established.We conducted a pooled analysis based on primary data from nine studies on EMF and childhood leukaemia, addressing three specific questions:1. Do the combined results of these studies indicate that there is an association between EMF exposure and childhood leukaemia risk, which is larger than one would expect from random variability?2. Does adjustment for confounding from socioeconomic class, mobility, level of urbanization, detached/not detached dwelling, and level of traffic exhaust change the results? 3. Do the combined data support the existence of the so-called wire code paradox, that is, a stronger association between proxy measures of EMF and cancer than between direct measurements and cancer? METHODSThe original plan for this project was to include all European studies that addressed the question of an association between EMF and childhood leukaemia and were based on either 24 or 48 hour magnetic field measurements or calculated fields. At the time five such studies were reported (Feychting and Ahlbom, 1993; Olsen et al, 1993;Verkasalo et al, 1993;Tynes and Haldorsen, 1997;Michaelis et al, 1998). In addition, a nationwide childhood cancer study was in progress and near completion in the UK (UKCCS, 1999). Since we were not aware of any other European study to be published in the near future, the inclusion of the UK study would give us a complete set of European studies. We felt that if we could also incorporate new studies from non-European countries this pooled analysis would be up to date and presumably stay current for several years. We were aware of three more studies in other parts of the world with compatible information that were all nearly A pooled analysis of magnetic fields and childhood leukaemia Summary Previous studies have suggested an association between exposure to 50-60 Hz magnetic fields (EMF) and childhood leukaemia. We conducted a pooled analysis based on individual records from nine studies, including the most recent ones. Studies with 24/48-hour magnetic field measurements or calculated magnetic fields were included. We specified which data analyses we planned to do and how to do them before we commenced the work. The use of individual records allowed us to use the same exposure definitions, and the large numbers of subjects enabled more precise estimation of risks at high exposure levels. For the 3203 children with leukae...

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Section: Methodsmentioning

confidence: 99%

A pooled analysis of magnetic fields and childhood leukaemia

et al. 2000

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“…More recent studies have reported no or little association between wire -code category and childhood cancer (Linet et al, 1997;McBride et al, 1999 ) and suggestive associations between childhood cancer and measured fields . Thus, the linkage among wire -code categories, magnetic -field attributes, and health remains inconsistent and uncertain.…”

Section: Introductionmentioning

confidence: 98%

Results of a multisite study of U.S. residential magnetic fields

Rankin

Bracken²,

Senior³

et al. 2002

J Expo Sci Environ Epidemiol

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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 > 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, > 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; betweenvisit 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.

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“…A study from New Zealand (Dockerty et al, 1998) found no significant increase in risk using as exposure metrics the means of two 24-h measurements made in the centre of the most used room and by the child's bed. Two recent Canadian studies (McBride et al, 1999;Green et al, 1999) found no increase in risk using 48-h personal monitoring. The influence of the body on the electric field during personal monitoring, together with the possibility that case children may have changed their behaviour since developing the disease make these results hard to interpret.…”

Section: Discussionmentioning

confidence: 90%

Exposure to power frequency electric fields and the risk of childhood cancer in the UK

Skinner

Mee²,

Blackwell³

et al. 2002

Br J Cancer

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The United Kingdom Childhood Cancer Study, a population-based case -control study covering the whole of Great Britain, incorporated a pilot study measuring electric fields. Measurements were made in the homes of 473 children who were diagnosed with a malignant neoplasm between 1992 and 1996 and who were aged 0 -14 at diagnosis, together with 453 controls matched on age, sex and geographical location. Exposure assessments comprised resultant spot measurements in the child's bedroom and the family living-room. Temporal stability of bedroom fields was investigated through continuous logging of the 48-h vertical component at the child's bedside supported by repeat spot measurements. The principal exposure metric used was the mean of the pillow and bed centre measurements. For the 273 cases and 276 controls with fully validated measures, comparing those with a measured electric field exposure 520 V m 71 to those in a reference category of exposure 510 V m 71 , odds ratios of 1.31 (95% confidence interval 0.68 -2.54) for acute lymphoblastic leukaemia, 1.32 (95% confidence interval 0.73 -2.39) for total leukaemia, 2.12 (95% confidence interval 0.78 -5.78) for central nervous system cancers and 1.26 (95% confidence interval 0.77 -2.07) for all malignancies were obtained. When considering the 426 cases and 419 controls with no invalid measures, the corresponding odds ratios were 0.86 (95% confidence interval 0.49 -1.51) for acute lymphoblastic leukaemia, 0.93 (95% confidence interval 0.56 -1.54) for total leukaemia, 1.43 (95% confidence interval 0.68 -3.02) for central nervous system cancers and 0.90 (95% confidence interval 0.59 -1.35) for all malignancies. With exposure modelled as a continuous variable, odds ratios for an increase in the principal metric of 10 V m 71 were close to unity for all disease categories, never differing significantly from one.

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Power-Frequency Electric and Magnetic Fields and Risk of Childhood Leukemia in Canada

Cited by 203 publications

References 16 publications

A pooled analysis of magnetic fields and childhood leukaemia

A pooled analysis of magnetic fields and childhood leukaemia

Results of a multisite study of U.S. residential magnetic fields

Exposure to power frequency electric fields and the risk of childhood cancer in the UK

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