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  • Occupational Health and Environmental Toxicology
  • Wiley-Blackwell  (511)
  • 1990-1994  (288)
  • 1980-1984  (223)
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  • Wiley-Blackwell  (511)
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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 15 (1994), S. 483-487 
    ISSN: 0197-8462
    Keywords: ELF magnetic field ; dosimetry ; electric field probe ; tissue conductivity ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Measuring internal induced electric fields in animals with a miniaturized probe involves a potential error related to the difference between the hole conductivity (σh) and the surrounding tissue conductivity (σt). Theory was developed to describe this phenomenon and checked by probe measurements in agar-filled petri dishes. The value measured in the hole is 2σt/(σh + σt) times the actual field in the tissue. For example, a probe hole in muscle, which is filled with blood, could yield a measurement only about 22% of the true value in the muscle. This potential source of error can be mitigated to some extent by not actually cutting a hole, by using a low-conductivity (e.g., 0.2 S/m) coupling medium in the hole, or by ensuring contact between the probe's electrodes and the tissue. © 1994 Wiley-Liss, Inc.
    Additional Material: 1 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 15 (1994), S. 513-518 
    ISSN: 0197-8462
    Keywords: subchronic exposure ; rotating magnetic fields ; neuroendocrine hormone ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: We exposed rats to circularly polarized 50 Hz magnetic fields to determine if plasma testosterone concentration was affected. Previous experiments indicate that magnetic fields suppress the nighttime rise in melatonin, suggesting that other neuroendocrine changes might occur as well. Male Wistar-King rats were exposed almost continuously for 6 weeks to magnetic flux densities of 1,5, or 50 μT. Blood samples were obtained by decapitation at 12:00 h and 24:00 h. Plasma testosterone concentration showed a significant day-night difference, with a higher level at 12:00 h when studied in July and December, but the day-night difference disappeared when concentrations were studied in April. In three experiments, magnetic field exposure had no statistically significant effect on plasma testosterone levels compared with the sham-exposed groups. These findings indicate that 6 weeks of nearly continuous exposure to circularly polarized, 50 Hz magnetic fields did not change plasma testosterone concentration in rats. © 1994 Wiley-Liss, Inc.
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  • 3
    ISSN: 0197-8462
    Keywords: magnetic fields ; micelles ; photolysis ; triplet radical pair ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: The influence of 60-Hz magnetic fields on free radical reactions can be quantitatively predicted from the knowledge of the effect of static fields on free radical behavior. Studies of radical reactions in micellar systems show that the behavior under a 60-Hz field is identical to that under a static field at any given point in time. © 1994 Wiley-Liss, Inc.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 15 (1994), S. 519-529 
    ISSN: 0197-8462
    Keywords: electromagnetic fields ; occupational hazards ; fetal development ; carcinogenesis ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Given the current interest in potential carcinogenic and developmental effects of exposure to extremely-low-frequency electromagnetic fields, there is a need to identify cohorts of exposed female workers for future epidemiologic investigations. This study was designed to test the hypothesis that nurses working in neonatal intensive care units (NICU) may be significantly exposed to power-frequency magnetic fields. An electromagnetic field monitor was used to measure magnetic fields at distances of 5, 15, 30, and 60 cm from the surfaces of each device used in the NICU. Six female nurses assigned to the NICU (the “exposed” group) and six female nurses working in the normal newborn nursery (the “referent” group) wore EMDEX dosimeters for the entire duration of their 12 h shifts. An investigator kept a detailed log of each NICU subject's whereabouts for the first one-third of her shift. Magnetic fields at 5 cm from the front (defined by the nurses' usual work area) of the NICU devices ranged from less than 0.1 to 114 μT and in all cases decreased considerably with increasing distance. The geometric mean of the shift-time-weighted average exposure of the NICU nurses was 0.17 μT compared with 0.11 μT for the normal newborn nurses. The percentage of time when subjects were exposed to magnetic fields of 0.4 μT or greater ranged from 5.8% to 15.6% for the NICU nurses, 0.4% to 2.9% for five of the comparison group nurses, and was 9.4% for one of the normal newborn nurses with unidentified aberrantly high exposures. Log data revealed that the vast majority of observed peaks among NICU nurses occurred while subjects were in close proximity to infant bed units. We conclude that NICU nurses represent one female-intensive job sector with intermittent high exposures to ELF magnetic fields and encourage larger exposure studies of nurses in a variety of medical settings. © 1994 Wiley-Liss, Inc.
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  • 5
    ISSN: 0197-8462
    Keywords: cancer promotion ; initiation ; tumor incidence ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: The purpose of this study was to investigate the effects of 2.45 GHz microwave (MW) radiation on dimethylhydrazine (DMH)-induced colon cancer in mice. The subjects were 115 Balb/c mice 4 weeks of age. The animals were divided into group A (control), group B (DMH), group C (DMH + MW), and group D [DMH + 12-O-tetradecanoylphorbol-13-acetate (TPA)]. Radiation (10 mW/cm2) was delivered dorsally with the E field parallel to the mouse's long body axis in an anechoic chamber. Radiations were administered 3 hr daily, 6 days per week, over a period of 5 months. The average SAR was estimated to be 10-12 W/kg. During the course of radiation treatments, DMH was injected once per week. The tumor promoter TPA was administered once per week for 10 weeks, from the third week on, after the initial treatment. The incidence of tumors did not significantly differ between the three test groups (groups B, C, and D; P 〉 0.25). However, the number of tumors, the size of the tumors, and the incidence of protuberant and infiltrative types in tumor-bearing animals were higher in group D compared to groups B and C (P 〈 0.05). No difference was found between groups B and C (P 〉 0.25). The study indicates that 2.45 GHz microwave radiation at 10 mW/cm2 power density did not promote DMH-induced colon cancers in young mice. The study also showed that TPA could accelerate colon tumor production if a tumor was initiated. © 1994 Wiley-Liss, Inc.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 15 (1994), S. 217-238 
    ISSN: 0197-8462
    Keywords: AC/DC magnetic fields ; mathematical models ; ionic resonance ; IPR ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Theoretical models proposed to date have been unable to clearly predict biological results from exposure to low-intensity electric and magnetic fields (EMF). Recently a predictive ionic resonance model was proposed by Lednev, based on an earlier atomic spectroscopy theory described by Podgoretskii and Podgoretskii and Khrustalev. The ion parametric resonance (IPR) model developed in this paper corrects mathematical errors in the earlier Lednev model and extends that model to give explicit predictions of biological responses to parallel AC and DC magnetic fields caused by field-induced changes in combinations of ions within the biological system. Distinct response forms predicted by the IPR model depend explicitly on the experimentally controlled variables: magnetic flux densities of the AC and DC magnetic fields (Bac and Bdc, respectively); AC frequency (fac); and, implicitly, charge to mass ratio of target ions. After clarifying the IPR model and extending it to combinations of different resonant ions, this paper proposes a basic set of experiments to test the IPR model directly which do not rely on the choice of a particular specimen or endpoint. While the fundamental bases of the model are supported by a variety of other studies, the IPR model is necessarily heuristic when applied to biological systems, because it is based on the premise that the magnitude and form of magnetic field interactions with unhydrated resonant ions in critical biological structures alter ion-associated biological activities that may in turn be correlated with observable effects in living systems. © 1994 Wiley-Liss, Inc.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 15 (1994), S. 239-260 
    ISSN: 0197-8462
    Keywords: AC/DC magnetic fields ; neurite outgrowth ; nerve growth factor ; IPR ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: A companion paper describes a predictive ion parametric resonance (IPR) model of magnetic field interactions with biological systems based on a selective relation between the ratio of the flux density of the static magnetic field to the AC magnetic field and the charge-to-mass ratio of ions of biological relevance. Previous studies demonstrated that nerve growth factor (NGF)-stimulated neurite outgrowth (NO) in PC-12 cells can be inhibited by exposure to magnetic fields as a function of either magnetic field flux density or AC magnetic field frequency. The present work examines whether the PC-12 cell response to magnetic fields is consistent with the quasiperiodic, resonance-based predictions of the IPR model. We tested changes in each of the experimentally controllable variables [flux densities of the parallel components of the AC magnetic field (Bac) and the static magnetic field (Bdc) and the frequency of the AC magnetic field] over a range of exposure conditions sufficient to determine whether the IPR model is applicable. A multiple-coil exposure system independently controlled each of these critical quantities. The perpendicular static magnetic field was controlled to less than 2 mG for all tests. The first set of tests examined the NO response in cells exposed to 45 Hz Bac from 77 to 468 mG(rms) at a Bdc of 366 mG. Next, we examined an off-resonance condition using 20 mG Bdc with a 45 Hz AC field across a range of Bac between 7.9 and 21 mG(rms). Finally, we changed the AC frequency to 25 Hz, with a corresponding change in Bdc to 203 mG (to tune for the same set of ions as in the first test) and a Bac range from 78 to 181 mG(rms). In all cases the observed responses were consistent with predictions of the IPR model. These experimental results are the first to support in detail the validity of the fundamental relationships embodied in the IPR model. © 1994 Wiley-Liss, Inc.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 15 (1994) 
    ISSN: 0197-8462
    Keywords: Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 15 (1994), S. 275-282 
    ISSN: 0197-8462
    Keywords: EMF ; exposure assessment ; wire codes ; 60 Hz ; epidemiology ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Wire codes, introduced by Wertheimer and Leeper as a surrogate for residential magnetic fields, divide imputed exposure into several categories based on the configurations of electrical wiring within 40 m of homes. Using the data set gathered by Savitz et al. in the Denver, Colorado, area of the United States, we determined which of the wiring attributes that contribute to Wertheimer-Leeper coding are actually associated with lowpower magnetic fields measured in bedrooms of subjects. The results led us to propose a considerably simplified three-category form of the Wertheimer-Leeper code that 1) drops the distinctions between thick and thin primary wires and between first-span and other secondary lines, 2) adds a new distinction between open (i.e., conductors not in physical contact) and spun secondaries, and 3) explains as much of the between-home variability in log-transformed bedroom fields as does the five categories of the original Wertheimer-Leeper code. The data necessary to classify residences using the modified code are considerably simpler to obtain and should lead to more reliable results. A separate reanalysis of the Denver data set of Savitz et al. shows that the modified code yields risk estimates that are both precise and markedly elevated for the highest exposure category, suggesting that this code may be useful in other studies. © 1994 Wiley-Liss, Inc.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 15 (1994), S. 283-291 
    ISSN: 0197-8462
    Keywords: electromagnetic field ; protein synthesis ; Escherichia coli ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Escherichia coli JM83 {F- ara Δ(lac-proAB) rpsL [φ80dΔ(lacZ)M15]} in midlog growth phase at 30 °C were exposed to 60 Hz sinusoidal magnetic field of 3 mT of nonuniform diverging flux, inducing a nonuniform electric field with a maximum intensity of 32 μV/cm using an inductor coil. Exposed and unexposed control cells were maintained at 30.8 ± 0.1 °C and 30.5 ± 0.1 °C, respectively. Quadruplicate samples of exposed and unexposed E. coli cells were simultaneously radiolabeled with 35S-L-methionine at 10 min intervals over 2 hr. Radiochemical incorporation into proteins was analyzed via liquid scintillation counting and by denaturing 12.5% polyacrylamide gel electrophoresis. The results showed that E. coli exposed to a 60 Hz magnetic field of 3 mT exhibited no qualitative or quantitative changes in protein synthesis compared to unexposed cells. Thus small prokaryotic cells (less than 2 μm × 0.5 μm) under constant-temperature conditions do not alter their protein synthesis following exposure to 60 Hz magnetic fields at levels at 3 mT. © 1994 Wiley-Liss, Inc.
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