Effect of 26 week magnetic field exposures in a DMBA initiation–promotion mammary gland model in Sprague–Dawley rats

Boorman, Gary A.; Anderson, Larry E.; Morris, James E.; Sasser, L. B.; Mann, Peter C.; Grumbein, Sondra L.; Hailey, James R.; McNally, Alan; Sills, Robert C.; Haseman, Joseph K.

doi:10.1093/carcin/20.5.899

Cited by 28 publications

(22 citation statements)

References 23 publications

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“…Driven by concerns raised by epidemiologic studies suggesting a potential cancer risk after exposures to ELF-EMF field strengths above the average exposure of 2 mG (0.2 µT) (6,7,30), this study was designed to determine whether there was a biological effect relevant to the carcinogenic process. We used an in vitro cell differentiation system to determine if ELF-EMF could alter chemically induced differentiation and proliferation of Friend erythroleukemia cells.…”

Section: Discussionmentioning

confidence: 99%

Effect of electromagnetic field exposure on chemically induced differentiation of friend erythroleukemia cells.

Chen

Upham

Sun

et al. 2000

Environ Health Perspect

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Whether exposure of humans to extremely low frequency electromagnetic fields (ELF-EMF) can cause cancer is controversial and therefore needs further research. We used a Friend erythroleukemia cell line that can be chemically induced to differentiate to determine whether ELF-EMF could alter proliferation and differentiation in these cells in a manner similar to that of a chemical tumor promoter. Exposure of this cell line to 60 Hz ELF-EMF resulted in a dose dependent inhibition of differentiation, with maximal inhibition peaking at 40% and 40 mG (4 microT). ELF-EMF at 10 mG (1.0 microT) and 25 mG (2.5 microT) inhibited differentiation at 0 and 20%, respectively. ELF-EMF at 1.0 (100) and 10.0 G (1,000 microT) stimulated cell proliferation 50% above the sham-treated cells. The activity of telomerase, a marker of undifferentiated cells, decreased 100[times] when the cells were induced to differentiate under sham conditions, but when the cells were exposed to 0.5 G (50 microT) there was only a 10[times] decrease. In summary, ELF-EMF can partially block the differentiation of Friend erythroleukemia cells, and this results in a larger population of cells remaining in the undifferentiated, proliferative state, which is similar to the published results of Friend erythroleukemia cells treated with chemical-tumor promoters.

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Section: Discussionmentioning

confidence: 99%

Effect of electromagnetic field exposure on chemically induced differentiation of friend erythroleukemia cells.

Chen

Upham

Sun

et al. 2000

Environ Health Perspect

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“…Then, as before, these animals were continuously exposed to the MF during mating, gestation, and birth of the third generation. The total numbers of mice in the MF-exposed group evaluated in each generation were (29)(30)(31)(32)(33)(34)(35). The conditions under which these newly available experiments were conducted and the results obtained are in Table 2.…”

Section: Resultsmentioning

confidence: 99%

“…The 26-week study (33,35) was conducted using a single dose of DMBA (10 mg/rat) prior to MF exposure in contrast to the fractionated dose protocol used previously. This exposure protocol resulted in a tumor incidence (as determined by palpation) at 13 weeks of approximately 65% and at 26 weeks of 100%.…”

Section: Resultsmentioning

confidence: 99%

“…These include four pairs of lifetime or multigeneration exposure studies [(11-13) vs (16), (11-13) vs (14), (11)(12)(13) vs (15), and (14) vs (16)]; four pairs of studies using the rat mammary carcinoma promotion model [(29) vs (28), (32,38) vs (25)(26)(27), (33)(34)(35) vs (25,26,32,38), and (33,34) (the second 13-week study) vs (33,35) (the 26-week study)]; three pairs of studies using the mouse skin promotion/co-promotion model [(54) vs (58,59), (50) As shown in Table 6, aspects of the comprehensive 2-year chronic bioassay conducted by the NTP (11-13) overlap three independently conducted long-term chronic bioassays (14)(15)(16), and two of the latter three studies also have overlapping aspects (14,16 (28), (32,38) vs (25)(26)(27), and (33,34) (the second 13-week study) vs (33,35)…”

Section: Discussionmentioning

confidence: 99%

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Assessing the Potential Carcinogenic Activity of Magnetic Fields Using Animal Models

McCann¹,

Kavet²,

Rafferty³

2000

Environmental Health Perspectives

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We update our 1997 publication by reviewing 29 new reports of tests of magnetic fields (MFs) in six different in vivo animal models of carcinogenesis: 2-year, lifetime, or multigeneration exposure studies in rats or mice; and promotion/progression models (rat mammary carcinoma, rat liver focus, mouse skin, several models of human leukemia/lymphoma in rats and mice, and brain cancer in rats). Individual experiments are evaluated using a set of data quality criteria, and summary judgments are made across multiple experiments by applying a criterion of rough reproducibility. The potential for carcinogenicity of MFs is discussed in light of the significant body of carcinogenesis data from animal bioassays that now exists. Excluding abstracts, approximately 80% of the 41 completed studies identified in this and our previous review roughly satisfy data quality criteria. Among these studies, the criterion for independent reproducibility is not satisfied for any positive results but is satisfied for negative results in chronic bioassays in rats and mice and for negative results in both promotion and co-promotion assays using the SENCAR mouse skin model. Results of independent replication studies using the rat mammary carcinoma model were conflicting. We conclude that long-term exposure to continuous 50-or 60-Hz MFs in the range of 0.002-5 mT is unlikely to result in carcinogenesis in rats or mice. Though results of most promotion/progression assays are negative, a weak promoting effect of MFs under certain exposure conditions cannot be ruled out based on available data.

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“…However, attempts of other groups to replicate our findings failed [19,20,21], which led us to suggest that genetic differences between substrains of SD rats used in our and other studies may be involved [22]. This prompted us to compare different substrains of SD outbred rats in our laboratory in respect to MF effects on cell proliferation in the mammary gland, susceptibility to DMBA-induced mammary cancer, and MF effects on mammary tumor development and growth in the DMBA model [18].…”

Section: Introductionmentioning

confidence: 84%

Power Frequency Magnetic Fields Increase Cell Proliferation in the Mammary Gland of Female Fischer 344 Rats but Not Various Other Rat Strains or Substrains

Fedrowitz

Löscher²

2005

Oncology

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Epidemiological data have raised concerns about the relationship between exposure to power frequency magnetic fields (MFs) and breast cancer. We have shown previously that 50-Hz MFs at microtesla flux densities enhance mammary gland tumor development and growth in the 7,12-dimethylbenz[a]anthracene (DMBA) model of breast cancer in female Sprague-Dawley (SD) rats. We also demonstrated that MF exposure results in an enhanced proliferative activity of the mammary epithelium of SD rats, which is a likely explanation for the cocarcinogenic or tumor-promoting effects of MF exposure in the DMBA model. Comparison of different SD substrains indicated that the genetic background plays a pivotal role in these effects of MF exposure. This prompted us to compare the effects of MF exposure (100 µT, 2 weeks) on cell proliferation in the mammary gland in eight different strains and substrains of outbred and inbred rats. Proliferation of epithelial cells in the mammary tissue and adjacent skin was examined by labeling proliferating cells with bromodeoxyuridine (BrdU). In addition to the MF-sensitive SD substrain (SD1) previously used in our experiments, Fischer 344 rats were the only strain in which MF exposure significantly enhanced BrdU labeling in the mammary epithelium, indicating a marked increase in cell proliferation. The MF-induced increase in BrdU labeling in Fischer 344 rats was similar to that seen after DMBA application. Furthermore, whole mount analysis of mammary tissue from Fischer 344 rats demonstrated that MF exposure increased the number of terminal end buds, i.e. the site of origin of mammary carcinomas. By comparison with MF-insensitive inbred rat strains, Fischer 344 rats may serve to evaluate the genetic factors underlying sensitivity to cocarcinogenic or tumor-promoting effects of MF exposure.

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Effect of 26 week magnetic field exposures in a DMBA initiation–promotion mammary gland model in Sprague–Dawley rats

Cited by 28 publications

References 23 publications

Effect of electromagnetic field exposure on chemically induced differentiation of friend erythroleukemia cells.

Effect of electromagnetic field exposure on chemically induced differentiation of friend erythroleukemia cells.

Assessing the Potential Carcinogenic Activity of Magnetic Fields Using Animal Models

Power Frequency Magnetic Fields Increase Cell Proliferation in the Mammary Gland of Female Fischer 344 Rats but Not Various Other Rat Strains or Substrains

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