Testing Electromagnetic Fields for Potential Carcinogenic Activity: A Critical Review of Animal Models

McCann, Joyce; Kavet, Robert; Rafferty, Charles N.

doi:10.2307/3433399

Cited by 11 publications

(17 citation statements)

References 85 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Because epidemiologic studies linking EMF exposure to human cancer are generally considered not to be definitive (2), the results of animal cancer tests conducted under controlled laboratory conditions and over a wide range of exposure conditions are likely to be important in a risk assessment of EMF. The results of a number of such studies will soon be available [see McCann et al (8) for review]. Therefore, in developing a risk assessment strategy for EMF, it will be important to consider the degree to which new developments in risk assessment may affect assumptions made as to the qualitative and quantitative predictivity of animal tests for results in humans and whether the unique features of EMF require specific attention.…”

Section: Extrapolation Between Animal Cancer Tests and Humansmentioning

confidence: 99%

“…As these groups point out, because of difficulties in assessing exposures, potential bias and confounding, as well as the inconsistency of epidemiologic studies, much uncertainty remains. Recent animal studies point to the possibility that EMF, though most likely nongenotoxic (5-7), may have some potential to enhance the development of neoplasia [reviewed by the National Research Council (NRC) (2) and McCann et al (8)]. These promotion studies are currently undergoing independent replication (9).…”

mentioning

confidence: 99%

“…These promotion studies are currently undergoing independent replication (9). In the next few years, results from other carcinogenesis bioassays in animals [see McCann et al (8) for recent review], as well as from new epidemiologic and in vitro studies are also expected to become available. With such a comprehensive database available, it should be possible to conduct a more definitive analysis of the carcinogenic potential of EMF.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Cancer Risk Assessment of Extremely Low Frequency Electric and Magnetic Fields: A Critical Review of Methodology

McCann¹,

Kheifets²,

Rafferty³

1998

Environmental Health Perspectives

Self Cite

View full text Add to dashboard Cite

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. The National Institute of Environmental Health Sciences (NIEHS) and Brogan & Partners are collaborating with JSTOR to digitize, preserve and extend access to Environmental Health Perspectives. a strategy for extremely low frequency electric and magnetic fields (EMF). Approaches taken for chemical agents or ionizing radiation in six key topic areas are briefly reviewed, and then those areas are examined from the perspective of EMF, identifying issues to be addressed in developing a risk assessment strategy. The following recommendations are offered: 1) risk assessment should be viewed as an iterative process that informs an overall judgment as to health risk and consists of a complex of related activities incorporating both positive and negative data, tumor and nontumor end points, and human and nonhuman sources of information; 2) a hazard identification resulting in a condusion of weak or null effects, such as may be associated with EMF, will need to assign significant weight to animal cancer bioassays conducted under defined exposure conditions as well as to human epidemiologic studies; 3) a default factor to account for possible age differences in sensitivity to carcinogenesis should be induded in an EMF risk assessment; 4) lack of evidence of dose response and the apparent lack of DNA reactivity of EMF suggest that a safety (or uncertainty) factor or margin of exposure type of risk characterization may be most appropriate; and 5) an EMF risk assessment should permit at least tentative conclusions to be reached as to the limits of carcinogenic risk from exposure to EMF, and should also define an efficient research agenda aimed at clarifying uncertainties appropriate to a more complete assessment. Reviews * McCann et al.exposure to EMF. We discuss six key topic areas: 1) variability between different human populations or individuals; 2) extrapolation between animals and humans; 3) the choice of an appropriate dose metric; 4) dose-response assessment and risk characterization; 5) the use of nontumor response data in risk assessment; and 6) the uses of epidemiology in risk assessment. [Exposure assessment, an area critical to developing a risk assessment strategy for EMF, is not addressed in this review. For recent discussion of this topic, see Bracken et al. (25).] In a concluding section we offer several general recommendations that may help to guide the selection of risk assessment strategies for EMF.

show abstract

Section: Extrapolation Between Animal Cancer Tests and Humansmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Cancer Risk Assessment of Extremely Low Frequency Electric and Magnetic Fields: A Critical Review of Methodology

McCann¹,

Kheifets²,

Rafferty³

1998

Environmental Health Perspectives

Self Cite

View full text Add to dashboard Cite

show abstract

“…Because all known human carcinogens, including cocarcinogenic and cancer promoting agents, are also carcinogenic in experimental animals [Huff, 1993;Vainio and Wilbourn, 1993], various ELF MF cancer studies have been performed in animals [Holmberg, 1995;McCann et al, 1997;Lo Èscher and Liburdy, 1998;Portier and Wolfe, 1998]. Long-term bioassays in rodents demonstrated no unequivocal carcinogenic response [Portier and Wolfe, 1998].…”

Section: Introductionmentioning

confidence: 99%

“…Long-term bioassays in rodents demonstrated no unequivocal carcinogenic response [Portier and Wolfe, 1998]. Similarly, experimental models of multistage carcinogenesis failed to provide convincing evidence for a promoting effect of MF on chemically induced cancers [McCann et al, 1997;Lo Èscher and Liburdy, 1998;Portier and Wolfe, 1998]. However, when the multistep mammary cancer DMBA (7,12-dimethylbenz[a]anthracene) model in rats was used with a different approach than that used traditionally (i.e., repeated administrations of DMBA over a period of 4 weeks versus one administration of DMBA), our group previously found consistent and dose-dependent cocarcinogenic effects of ELF MF exposure [for review see Lo Èscher and Lo Èscher, 2001], indicating that alternative approaches are needed for testing the possible cocarcinogenic effects of MF.…”

Section: Introductionmentioning

confidence: 99%

Do cocarcinogenic effects of ELF electromagnetic fields require repeated long‐term interaction with carcinogens? Characteristics of positive studies using the DMBA breast cancer model in rats

Löscher

2001

Bioelectromagnetics

View full text Add to dashboard Cite

The carcinogenic or cocarcinogenic potential of extremely low frequency (ELF; 50 or 60 Hz) magnetic fields (MFs) has been evaluated worldwide in diverse animal model systems. Though most results have been negative, weakly positive or equivocal results have been reported in several cancer models, including the rat DMBA (7,12-dimethylbenz[a]anthracene) model of mammary cancer. Based on the experimental conditions used in studies in which cocarcinogenic effects of ELF MF were found, it was recently proposed that MF exposure may potentiate the effects of known carcinogens only when the animals are exposed to both MF and carcinogen during an extended period of tumor development, i.e., when the carcinogen is given repeatedly during MF exposure. This review summarizes a series of experiments from our group, showing cocarcinogenic MF effects in the DMBA breast cancer model in rats, to test whether the above proposal is confirmed by existing data. Flux densities of 50 or 100 microT significantly increased the growth of mammary tumors, independent of whether DMBA was given in a single administration or repeatedly over a prolonged period. Thus, these data do not substantiate the hypothesis requiring repeated doses of DMBA during MF exposure. Instead, several other aspects of study design and experimental factors are identified that seem to be critical for the detection of cocarcinogenic effects of MF exposure in the rat DMBA mammary cancer model. These include the rat subline used, the dose of DMBA, the duration of MF exposure, the flux density, the background (sham control) tumor incidence, and the location of mammary tumors in the mammary gland complex. These and other experimental aspects may explain why some laboratories did not detect cocarcinogenic MF effects in the DMBA model. We hope that direct comparison of MF bioeffects in different rat sublines and further evaluation of other experimental differences between studies on MF exposure in the DMBA model will eventually determine which genetic and environmental factors are critical for potential carcinogenic or cocarcinogenic effects of ELF MF exposure.

show abstract

Clinical progression of transplanted large granular lymphocytic leukemia in Fischer 344 rats exposed to 60 Hz magnetic fields

Morris

Sasser

Miller

et al. 1999

Bioelectromagnetics

View full text Add to dashboard Cite

The purpose of this study was to determine if 60 Hz magnetic fields can alter the clinical progression of leukemia in an animal model. Large granular lymphocytic (LGL) leukemia cells from spleens of leukemic rats were transplanted into young male Fischer 344 rats, producing signs of leukemia in approximately 2–3 months. The animals were randomly assigned to 4 treatment groups (108/group) as follows: 1) 10 G (1.0 mT) linearly polarized 60 Hz magnetic fields, 2) sham exposed [null energized unit with residual 20 mG (2 μT) fields], 3) ambient controls [<1 mG (0.1 μT)], and 4) positive controls (a single 5 Gy whole body exposure to 60Co 4 days prior to initiation of exposure). All rats were injected intraperitoneally (ip) with 2.2 × 107 LGL leukemic cells at the initiation of exposure or sham exposure. The magnetic fields were activated for 20 h/day, 7 days/week, allowing time for animal care. The experimental fields were in addition to natural ambient magnetic fields. Eighteen rats from each treatment group were bled, killed, and evaluated at 5, 6, 7, 8, 9, and 11 weeks of exposure. Peripheral blood hematological endpoints, changes in spleen growth, and LGL cell infiltration into the spleen and liver were measured to evaluate the leukemia progression. No significant or consistent differences were detected between the magnetic field exposed groups and the ambient control group, although the clinical progress of leukemia was enhanced in the positive control animals. These data indicate that exposure to sinusoidal, linearly polarized 60 Hz, 10 G magnetic fields did not significantly alter the clinical progression of LGL leukemia. Furthermore, the data are in general agreement with previous results of a companion repeated‐bleeding study in which animals were exposed for 18 weeks. Bioelectromagnetics 20:48–56, 1999. © 1999 Wiley‐Liss, Inc.

show abstract

Testing Electromagnetic Fields for Potential Carcinogenic Activity: A Critical Review of Animal Models

Abstract: In order to assess the potential of electromagnetic fields (EMF) 81-103 (1997)

Cited by 11 publications

References 85 publications

Cancer Risk Assessment of Extremely Low Frequency Electric and Magnetic Fields: A Critical Review of Methodology

Cancer Risk Assessment of Extremely Low Frequency Electric and Magnetic Fields: A Critical Review of Methodology

Do cocarcinogenic effects of ELF electromagnetic fields require repeated long‐term interaction with carcinogens? Characteristics of positive studies using the DMBA breast cancer model in rats

Clinical progression of transplanted large granular lymphocytic leukemia in Fischer 344 rats exposed to 60 Hz magnetic fields

Contact Info

Product

Resources

About