Magnetic fields and mammary cancer in rodents: a critical review and evaluation of published literature.
Epidemiological data suggesting a possible increase in breast cancer risk in male electricians have raised concerns about the relationship between exposure to power-frequency magnetic fields and breast cancer. In this paper, we review the results of animal studies that are relevant to identifying possible increases in breast cancer risk resulting from exposure to 50 or 60 Hz magnetic fields. Three large-scale chronic bioassays of carcinogenesis in rats or mice exposed to magnetic fields for 2 years demonstrated no increases in the incidence of mammary cancer; it is generally accepted that power-frequency magnetic fields have little or no activity as a complete carcinogen in the rodent mammary gland. Findings from one laboratory, though inconsistent, suggest that magnetic fields may stimulate mammary neoplasia in rats treated with a chemical carcinogen. However, studies conducted in two other laboratories failed to confirm these findings; rats exposed to magnetic fields demonstrated patterns of tumor incidence, multiplicity, size and latency that were generally similar to those in sham-exposed controls. Where differences were seen, the groups exposed to magnetic fields generally had fewer mammary tumors than did sham-exposed controls. On this basis, evaluations of the activity of 50 or 60 Hz magnetic fields in models of multistage mammary cancer in rodents have generally been negative; positive findings have been reported from only one laboratory. The totality of rodent data does not support the hypothesis that power-frequency magnetic-field exposure enhances mammary cancer in rodents, nor does it provide experimental support for possible epidemiological associations between magnetic-field exposure and increased breast cancer risk.
Boorman
G A
GA
National Institute of Environmental Health Sciences, P.O. Box 12233, Research Triangle Park, North Carolina 27709, USA.
McCormick
D L
DL
Ward
J M
JM
Haseman
J K
JK
Sills
R C
RC
D015127:9,10-Dimethyl-1,2-benzanthracene; D000236:Adenoma / Q000139:chemically induced / Q000209:etiology; D000818:Animals; D001681:Biological Assay; D002273:Carcinogens; D002277:Carcinoma / Q000209:etiology*; D002471:Cell Transformation, Neoplastic / Q000528:radiation effects*; D004195:Disease Models, Animal; D004574:Electromagnetic Fields / Q000009:adverse effects*; D005260:Female; D018226:Fibroadenoma / Q000139:chemically induced / Q000209:etiology; D008297:Male; D008321:Mammary Glands, Animal / Q000528:radiation effects*; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced / Q000209:etiology*; D051379:Mice; D051381:Rats
D002273:Carcinogens; D015127:9,10-Dimethyl-1,2-benzanthracene