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13616 views
08:44 Apr-19-1999

Godfrey Hands

Engineering,
PRI Nadcap,
United Kingdom,
Joined Nov 1998
281
Magnetic Particle Radiation Hazards

Can anyone please help me.
I am lookin for references to the electromagnetic radiation hazards that operators of MPI are exposed to.
If I remember correctly, there was an article in Materials Evaluation some years ago on the subject.
There is also study results from Sweden that show an increased incidence of cancer in the brian from drivers of electric locomotives. Does anybody have references to that?

Regards,
Godfrey Hands


 
08:13 Apr-19-1999

Robert (Rocky) A. Day

Engineering
Milky Way Jewels,
USA,
Joined Nov 1998
40
Re: Magnetic Particle Radiation Hazards I would recommend Kenneth R. Foster's "Phantom Risk: Scientific Inference and the Law" a common sense approach to this issue. Ken has an excellent discussion of the history of this issue.

Most studies relating to EM fields relate to low level exposure. Studies are controversial but the National Academy of Sciences recently concluded that there is no evidence to support a health effect for such exposures.

Magnetic Particle Inspection apparatus produce much larger fields and most operators spend significant time in these fields. As far as I know no health effects have been reported for this population.

Regards,
Robert (Rocky) A. Day
Second Sound
Ultrasonic Transducers
904 Cortland Avenue
San Francisco, CA 94110 - 5633
(415) 641-4947
Fax: (415) 641-5502

: Can anyone please help me.
: I am lookin for references to the electromagnetic radiation hazards that operators of MPI are exposed to.
: If I remember correctly, there was an article in Materials Evaluation some years ago on the subject.
: There is also study results from Sweden that show an increased incidence of cancer in the brian from drivers of electric locomotives. Does anybody have references to that?

: Regards,
: Godfrey Hands




 
01:14 Apr-25-1999

Michael Trinidad

Consultant, API 510 570 & 653
Marine Inspection Service Pty Ltd (MIS),
Australia,
Joined Jan 2003
138
Re: Magnetic Particle Radiation Hazards In Australia I know the electricity companies have set levels for electro magnetism emitted from transformers etc. An over zealous safety rep whilst I was in the army called in one of the electricty board inspectors to measure the output on the MPI bench.

The inspector's recommendation was that any further use of the coil that operators must use long handled tongs to manipulate the parts. Needless to say as soon as he was out the door he was dieregarded. The inspector did want to know if I ever experienced flashing in my eyes as he said the magnetic field can greatly effect the retina.

Regards

Michael Trinidad




 
02:45 Apr-25-1999

Robert (Rocky) A. Day

Engineering
Milky Way Jewels,
USA,
Joined Nov 1998
40
Re: Magnetic Particle Radiation Hazards Here is some review of the literature on the health effects of magnetic fields. The field strengths encountered in MT are unknown but the study of welders exposure may give some idea. Studies detailed here are largely for workers exposed to magnetic and electric fields. It is not known if exposure to only magnetic fields (MT is only magnetic fields) changes the risk factors, if any.

The selected abstracts are intended to provide a flavor of recent research on this subject. The National Academy of Science has concluded that EMF doesn't produce health effects at doses encountered in normal activities. A limited number of copies of the report entitled EMF Research Activities Completed Under the Energy Policy Act of 1992 are available from the Board on Radiation Effects Research of the Commission on Life Sciences, the National Research Council, 2101 Constitution Ave, NW, Washington, DC 20418. It is not clear what relationship this may have to MT exposure if any.

The National Institute of Healths web site on this subject may also be helpful:
http://www.niehs.nih.gov/emfrapid/home.htm

The principle of prudent avoidance states that risks that do not provide benefits should be avoided. The inconvenience of using tongs and keeping away from the fields we use in MT must be weighted against the possible harm magnetic field might have.

The genotoxic potential of electric and magnetic fields: an update.
McCann J, Dietrich F, Rafferty C
Mutat Res 1998 Aug 411:1 45-86

Abstract
We review 23 studies on the potential genotoxicity of electric and magnetic fields that have appeared in the published literature since our 1993 review of 55 published studies (McCann et al., Mutat. Res. 297 (1993) 61-95) and six additional studies published prior to 1993, which were not previously reviewed. As in our previous review, internal electric fields present in media (for in vitro experiments) and in the torso (for in vivo experiments) were estimated. Individual experiments are evaluated using basic data quality criteria. The potential for genotoxicity of electric and magnetic fields is discussed in light of the significant body of genotoxicity data that now exists. Three unsuccessful attempts to replicate previously reported positive results have appeared since our previous review. We conclude that, in spite of the 34 studies reviewed in this and our previous publication that report positive genotoxic effects, none satisfy all of three basic conditions: independent reproducibility, consistency with the scientific knowledge base, and completeness according to basic data quality criteria. As we discuss, these criteria are satisfied for several groups of negative studies in several exposure categories (ELF magnetic fields, 150 microT-5 mT, combined ELF electric and ELF magnetic fields, approx. 0.2 mT, 240 mV/m, and static magnetic fields, 1-3.7 T). The evidence reviewed here strengthens the conclusion of our previous review, that the preponderance of evidence suggests that ELF electric or magnetic fields do not have genotoxic potential. Nevertheless, a pool of positive results remains, which have not yet been tested by independent replication. Among the 12 studies reviewed here, which report statistically significant or suggestive positive results, we point particularly to results from five laboratories [J. Miyakoshi, N. Yamagishi, S. Ohtsu, K. Mohri, H. Takebe, Increase in hypoxanthine-guanine phosphoribosyl transferase gene mutations by exposure to high-density 50-Hz magnetic fields, Mutat. Res. 349 (1996) 109-114; J. Miyakoshi, K. Kitagawa, H. Takebe, Mutation induction by high-density, 50-Hz magnetic fields in human MeWo cells exposed in the DNA synthesis phase, Int. J. Radiat. Biol. 71 (1997) 75-79; H. Lai. N.P. Singh, Acute exposure to a 60-Hz magnetic field increases DNA strand breaks in rat brain cells, Bioelectromagnetics, 18 (1997) 156-165; H. Lai, N.P. Singh, Melatonin and N-tert-butyl-alpha-phenylnitrone block 60-Hz magnetic field-induced DNA single and double strand breaks in rat brain cells, J. Pineal Res. 22 (1997) 152-162; T. Koana, M. Ikehata, M. Nakagawa, Estimation of genetic effects of a static magnetic field by a somatic cell test using mutagen-sensitive mutants of Drosophila melanogaster, Bioelectrochem. Bioenergetics 36 (1995) 95-100; F.L. Tabrah, H.F. Mower, S. Batkin, P.B. Greenwood, Enhanced mutagenic effect of a 60-Hz time-varying magnetic field on numbers of azide-induced TA100 revertant colonies, Bioelectromagnetics 15 (1994) 85-93; S. Tofani, A. Ferrara, L. Anglesio, G. Gilli, Evidence for genotoxic effects of resonant ELF magnetic fields, Bioelectrochem. Bioenergetics, 36 (1995) 9-13], which satisfy most basic data quality criteria and may be of interest. Copyright 1998 Elsevier Science B.V. All rights reserved.

Hypothesis: the risk of childhood leukemia is related to combinations of power-frequency and static magnetic fields.
Bowman JD, Thomas DC, London SJ, Peters JM
Bioelectromagnetics 1995 16:1 48-59

Abstract
We present a hypothesis that the risk of childhood leukemia is related to exposure to specific combinations of static and extremely-low-frequency (ELF) magnetic fields. Laboratory data from calcium efflux and diatom mobility experiments were used with the gyromagnetic equation to predict combinations of 60 Hz and static magnetic fields hypothesized to enhance leukemia risk. The laboratory data predicted 19 bands of the static field magnitude with a bandwidth of 9.1 microT that, together with 60 Hz magnetic fields, are expected to have biological activity. We then assessed the association between this exposure metric and childhood leukemia using data from a case-control study in Los Angeles County. ELF and static magnetic fields were measured in the bedrooms of 124 cases determined from a tumor registry and 99 controls drawn from friends and random digit dialing. Among these subjects, 26 cases and 20 controls were exposed to static magnetic fields lying in the predicted bands of biological activity centered at 38.0 microT and 50.6 microT. Although no association was found for childhood leukemia in relation to measured ELF or static magnetic fields alone, an increasing trend of leukemia risk with measured ELF fields was found for subjects within these static field bands (P for trend = 0.041). The odds ratio (OR) was 3.3 [95% confidence interval (CI) = 0.4-30.5] for subjects exposed to static fields within the derived bands and to ELF magnetic field above 0.30 microT (compared to subjects exposed to static fields outside the bands and ELF magnetic fields below 0.07 microT). When the 60 Hz magnetic fields were assessed according to the Wertheimer-Leeper code for wiring configurations, leukemia risks were again greater with the hypothesized exposure conditions (OR = 9.2 for very high current configurations within the static field bands; 95% CI = 1.3-64.6). Although the risk estimates are based on limited magnetic field measurements for a small number of subjects, these findings suggest that the risk of childhood leukemia may be related to the combined effects of the static and ELF magneticfields. Further tests of the hypothesis are proposed.

Introduction to power-frequency electric and magnetic fields.
Kaune WT
Environ Health Perspect 1993 Dec 101 Suppl 4 73-81

Abstract
This paper introduces the reader to electric and magnetic fields, particularly those fields produced by electric power systems and other sources using frequencies in the power-frequency range. Electric fields are produced by electric charges; a magnetic field also is produced if these charges are in motion. Electric fields exert forces on other charges; if in motion, these charges will experience magnetic forces. Power-frequency electric and magnetic fields induce electric currents in conducting bodies such as living organisms. The current density vector is used to describe the distribution of current within a body. The surface of the human body is an excellent shield for power-frequency electric fields, but power-frequency magnetic fields penetrate without significant attenuation; the electric fields induced inside the body by either exposure are comparable in magnitude. Electric fields induced inside a human by most environmental electric and magnetic fields appear to be small in magnitude compared to levels naturally occurring in living tissues. Detection of such fields thus would seem to require the existence of unknown biological mechanisms. Complete characterization of a power-frequency field requires measurement of the magnitudes and electrical phases of the fundamental and harmonic amplitudes of its three vector components. Most available instrumentation measures only a small subset, or some weighted average, of these quantities. Hand-held survey meters have been used widely to measure power-frequency electric and magnetic fields. Automated data-acquisition systems have come into use more recently to make electric- and magnetic-field recordings, covering periods of hours to days, in residences and other environments.(ABSTRACT TRUNCATED AT 250 WORDS)

Exposure of welders and other metal workers to ELF magnetic fields.
Skotte JH, Hjøllund HI
Bioelectromagnetics 1997 18:7 470-7

Abstract
This study assessed exposure to extremely low frequency (ELF) magnetic fields of welders and other metal workers and compared exposure from different welding processes. Exposure to ELF magnetic fields was measured for 50 workers selected from a nationwide cohort of metal workers and 15 nonrandomly selected full-time welders in a shipyard. The measurements were carried out with personal exposure meters during 3 days of work for the metal workers and I day of work for the shipyard welders. To record a large dynamic range of ELF magnetic field values, the measurements were carried out with ''high/low'' pairs of personal exposure meters. Additional measurements of static magnetic fields at fixed positions close to welding installations were done with a Hall-effect fluxmeter. The total time of measurement was 1273 hours. The metal workers reported welding activity for 5.8% of the time, and the median of the work-period mean exposure to ELF magnetic fields was 0.18 microT. DC metal inert or active gas welding (MIG/MAG) was used 80% of the time for welding, and AC manual metal arc welding (MMA) was used 10% of the time. The shipyard welders reported welding activity for 56% of the time, and the median and maximum of the workday mean exposure to ELF magnetic fields was 4.70 and 27.5 microT, respectively. For full-shift welders the average workday mean was 21.2 microT for MMA welders and 2.3 microT for MIG/MAG welders. The average exposure during the effective time of welding was estimated to be 65 microT for the MMA welding process and 7 microT for the MIG/MAG welding process. The time of exposure above 1 microT was found to be a useful measure of the effective time of welding. Large differences in exposure to ELF magnetic fields were found between different groups of welders, depending on the welding process and effective time of welding. MMA (AC) welding caused roughly 10 times higher exposure to ELF magnetic fields compared with MIG/MAG (DC) welding. The measurements of static fields suggest that the combined exposure to static and ELF fields of MIG/MAG (DC) welders and the exposure to ELF fields of MMA (AC) welders are roughly of the same level.

Assessing human exposure to power-frequency electric and magnetic fields.
Kaune WT
Environ Health Perspect 1993 Dec 101 Suppl 4 121-33

Abstract
This paper reviews published literature and current problems relating to the assessment of occupational and residential human exposures to power-frequency electric and magnetic fields. Available occupational exposure data suggest that the class of job titles known as electrical workers may be an effective surrogate for time-weighted-average (TWA) magnetic-field (but not electric-field) exposure. Current research in occupational-exposure assessment is directed to the construction of job-exposure matrices based on electric- and magnetic-field measurements and estimates of worker exposures to chemicals and other factors of interest. Recent work has identified five principal sources of residential magnetic fields: electric power transmission lines, electric power distribution lines, ground currents, home wiring, and home appliances. Existing residential-exposure assessments have used one or more of the following techniques: questionnaires, wiring configuration coding, theoretical field calculations, spot electric- and magnetic-field measurements, fixed-site magnetic-field recordings, personal- exposure measurements, and geomagnetic-field measurements. Available normal-power magnetic-field data for residences differ substantially between studies. It is not known if these differences are due to geographical differences, differences in measurement protocols, or instrumentation differences. Wiring codes and measured magnetic fields (but not electric fields) are associated weakly. Available data suggest, but are far from proving, that spot measurements may be more effective than wire codes as predictors of long-term historical magnetic-field exposure. Two studies find that away-from-home TWA magnetic-field exposures are less variable than at-home exposures. The importance of home appliances as contributors to total residential magnetic-field exposure is not known at this time. It also is not known what characteristics (if any) of residential electric and magnetic fields are determinants of human health effects.

[Occupational risk among magnetic resonance workers. Analysis of the literature]
Magnavita N, Fileni A
Radiol Med (Torino) 1995 May 89:5 662-6

Vernaclular Title
Il rischio professionale negli addetti alla Risonanza Magnetica. Analisi della letteratura.

Abstract
It was observed that ''medical diagnosis utilizing Magnetic Resonance (MR) scanners may be one of the first modalities in which there is more risk for the operator of the equipment than for the patient'' (Young, 1984). Despite this statement, only a few studies have been devoted to the assessment of occupational hazard in MR imaging personnel. The principal features associated with MR systems are: static magnetic fields, time-varying magnetic fields, and radiofrequency irradiation. Potential medical effects related to these hazards are reviewed. Static magnetic fields are known to induce in vitro changes in enzyme kinetics, orientation changes of macromolecules and subcellular components, distortion of ion currents and magnetohydrodynamic effects. Possible mechanisms for static magnetic field bioeffects include the exertion of magnetic forces, the induction of voltages, and other mechanisms (proton tunneling, ion cyclotron resonance) that are yet scarcely known. Human epidemiological studies on static magnetic fields are mainly based on subjective observations, and lack adequate control for confounding factors. Time-varying magnetic fields in the extremely-low frequency range have been associated with both occupational and non-occupational adverse health effects. Exposure to electromagnetic fields in office workers has been related to an increased rate of abortion; the vast majority of studies in this field, however, did not reach any significant result. Many literature reports support the evidence of an elevation of cancer risk in subjects exposed to residential and occupational ELF fields. Although such observations are not yet proved, the alleged occupational risk in magnetic fields exposure should induce to optimize exposure in MR imaging workers.: Can anyone please help me.
: I am lookin for references to the electromagnetic radiation hazards that operators of MPI are exposed to.
: If I remember correctly, there was an article in Materials Evaluation some years ago on the subject.
: There is also study results from Sweden that show an increased incidence of cancer in the brian from drivers of electric locomotives. Does anybody have references to that?

: Regards,
: Godfrey Hands




 
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