type of study, country |
category/magnitude/exposure metric category |
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cases |
(95% CI) |
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| (Floderus et al., 1993); case- control, Sweden |
All male workers in a large region of mid-Sweden who were 20-64 years old in 1980. 346 brain cancer cases from cancer registry, 1121 controls matched on age from census records. | Exposures from JEMs for TWA and 3 other metrics in job held the longest in the 10 years before diagnosis. JEMs for 169 job categories based on 1015 magnetic field measurements taken at subject's workplace and job (or surrogate). |
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With 90th percentile of the median magnetic fields, risk for all brain tumors is 1.6 (1.0-2.6). No change significant in risks after adjustment for benzene, ionizing radiation, or solvent exposures | ||||||||||||||||||||||||||||||||||||||
| (Sahl et al., 1993); case- control, California (USA) |
36221 southern California Edison Company utility workers. Cancer mortality determined from 1960-88. 10 controls per case matched on date of birth, gender, and race with 32 brain cancer cases | Exposure based on job history and JEMs for TWA and 4 other metrics from 776 person-days of magnetic field measurements in the current electric utility working environment |
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OR increase per defined exposure magnitude calculated by conditional logistic regression | ||||||||||||||||||||||||||||||||||||||
| (Thériault et al., 1994); case- control, Canada and France |
Cohorts of male utility workers in 3 large companies: base population of 223292; 4151 cancer cases (250 brain cancer) determined from cancer registries, company records, etc. 6106 controls matched to cases by utility and date of birth | Cumulative exposure based on job history plus JEMs from 2066 work-week EMF measurements (50/60 Hz magnetic fields, electric fields and pulsed EMF). JEMs for TWAs adjusted for past practices constructed for 260 job titles |
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Trend calculated over 4 exposure groups. Astrocytoma OR in high exposure group much reduced when calculated by exact method for small sample. | ||||||||||||||||||||||||||||||||||||||
| (Savitz & Loomis, 1995); Historic cohort study, USA |
138905 men employed for > 6 months in 5 electric utilities followed for mortality 1950-86,; 144 deaths from brain and CNS cancers | Cumulative magnetic field exposure estimated from job history plus JEM based on 2842 magnetic field measurements. JEM constructed for 28 occupational categories (120 location-specific categories) collapsed into 5 exposure groups for TWA |
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Risks adjusted for PCB and solvent exposures. Ionizing radiation exposure insignificant. | ||||||||||||||||||||||||||||||||||||||
| (Feychting et al., 1997); case- control, Sweden |
Combined occupational and residential exposure assessment.: approximately 400000 subjects living within 300 m of transmission lines; 223 CNS tumor cases. | Residential magnetic field exposure from physical model of historical fields from transmission lines. Occupational exposure estimated from JEM developed by (Floderus et al., 1993) |
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| (Harrington et al., 1997); case- control, UK |
84018 utility workers at the Central Electricity Generating Board of England and Wales. 112 deaths from primary brain cancers matched to 654 controls by gender and date of birth. | Magnetic field exposure estimated from computerized job histories and a JEM based on limited measurements on 127 workers. Many subjects unclassifiable because of gaps in job records or JEM. |
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Unclassifiable cases and controls had an OR = 2.0 (CI = 1.1-4.4).No associations with 24 potential confounders | ||||||||||||||||||||||||||||||||||||||
| (Johansen & Olsen, 1998); Retrospective cohort, Denmark |
Male and female employees of 99 Danish utility companies, 46284 total. | Magnetic field exposures for subject's first job taken from a JEM based on expert judgment and 24-h measurements on 129 workers at 6 companies. JEM has 5 exposure categories (including background and unknown) |
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Risks calculated as SIR relative to background. For women employed> 10 years, the risk for low exposure is significant (SIR = 9.2 for 2 cases) | ||||||||||||||||||||||||||||||||||||||