title: Personal power-frequency magnetic field exposure in women recruited at an infertility clinic: association with physical activity and temporal variability.
abstract: Current epidemiologic approaches for studying exposure to power-frequency magnetic fields and the risk of miscarriage are potentially biased due to lack of attention to the relationship of exposure with physical activity and within-individual variability in exposures over time. This analysis examines these two issues using data from a longitudinal pilot study of 40 women recruited from an infertility clinic that contributed data for up to three 24-h periods separated by a median of 3.6 weeks. Physical activity was positively associated with peak exposure metrics. Higher physical activity within environments did not necessarily lead to higher peak exposures, suggesting that movement between and not within environments increases one's probability of encountering a high field source. Peak compared with central tendency metrics were more variable over time. Future epidemiology studies associated with peak exposure metrics should adjust for physical activity and collect more than 1 d of exposure measurement to reduce bias.
authors.affiliation: Department of Environmental Health Sciences, University of Michigan School of Public Health, 1835 SPH I, 1415 Washington Heights, Ann Arbor, MI 48109, USA.
authors.forename: Ryan C
authors.initials: RC
authors.lastname: Lewis
authors.affiliation: Department of Environmental Health, Harvard School of Public Health, Building I, 14th Floor, 665 Huntington Avenue, Boston, MA 02115, USA Vincent Memorial Obstetrics and Gynecology Service, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA.
authors.forename: Russ
authors.initials: R
authors.lastname: Hauser
authors.affiliation: Department of Biostatistics, University of Michigan School of Public Health, M4132 SPH II, 1415 Washington Heights, Ann Arbor, MI 48109, USA.
authors.forename: Lu
authors.initials: L
authors.lastname: Wang
authors.affiliation: Electric Power Research Institute, 3420 Hillview Avenue, Palo Alto, CA 94304, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Kavet
authors.affiliation: Department of Environmental Health Sciences, University of Michigan School of Public Health, 1835 SPH I, 1415 Washington Heights, Ann Arbor, MI 48109, USA meekerj@umich.edu.
authors.forename: John D
authors.initials: JD
authors.lastname: Meeker
mesh_terms: D000328:Adult; D004574:Electromagnetic Fields / Q000009:adverse effects*; D004781:Environmental Exposure / Q000032:analysis*; D005260:Female; D006801:Humans; D015994:Incidence; D007246:Infertility / Q000453:epidemiology* / Q000209:etiology; D009043:Motor Activity / Q000528:radiation effects*; D010865:Pilot Projects; D012307:Risk Factors; D014481:United States / Q000453:epidemiology