Evaluation of the potential carcinogenicity of 60 Hz linear sinusoidal continuous‐wave magnetic fields in Fischer F344 rats

Abstract

Electric and magnetic fields (EMFs) associated with the production, transmission, and use of electricity are ubiquitous in industrialized societies. These fields are predominantly of low frequency (50/60 Hz) and are generally of low intensity. Review of the epidemiological evidence shows that the association between exposure to EMFs and cancer is weak and inconsistent, and generally fails to show a dose-response relationship. Moreover, in view of the methodological problems of these epidemiological studies, animal and laboratory studies are urgently needed to determine whether EMFs could be initiators and/or promoters of cancers. The objective of the present study was to determine whether chronic exposure to 60 Hz linear (single axis) sinusoidal, continuous-wave magnetic fields (MFs) of different intensities might increase the risk of leukemia and solid tumor development in rodents born and raised under these fields. Five groups of 50 female F344 rats were exposed for 20 h/day to 60 Hz MFs at intensities of <0.02 (sham controls), 2, 20, 200, and 2000 microT. Full body exposure to the different fields was administered for 104 wk starting from the prenatal period (2 days before birth) and continuing during lactation and weaning until late adult life. Body weight, survival, and clinical observations were evaluated in all groups of animals during in-life exposure. Necropsy was performed on all exposed and control animals that died, were found moribund, or were killed at termination of the study. To preserve and demonstrate the absence of any experimental bias, all clinical observations and pathological evaluations were conducted under "blinded" conditions. Fifty organs and tissues were evaluated in each animal, with special attention to the incidence of mononuclear cell leukemia, brain tumors, and mammary tumors. The findings from this chronic carcinogenicity study demonstrate that, under our defined experimental conditions, exposure to 60 Hz linear (single axis) sinusoidal, continuous wave MFs did not affect animal survival, solid tumor, or mononuclear cell leukemia development in female F344 rats. No statistically significant, consistent, positive dose-related trends with the number of tumor-bearing animals per study group could be attributed to MF exposure.

Chronic Toxicity/Oncogenicity Evaluation of 60 Hz (Power Frequency) Magnetic Fields in F344/N Rats

“…However, when considered together, long-term exposure of rodents to power frequency magnetic fields that are 5,000-to 10,000-fold (the present study), 10,000-to 20,000-fold (30), and 50,000-to 100,000-fold (56) higher than field levels that are routinely encountered in residential environments has demonstrated no pattern of increased cancer risk. These data, when considered as a whole, provide little or no evidence that exposure to pure 60 Hz linear magnetic fields at up to 10 G field intensities for up to 2 yr can affect neoplastic development in the F344/N rat.…”

“…In the Linet study, however, a small increase in risk for childhood leukemia was seen in residential exposures of about 3 mG (28). At (30). Similarly, a Japanese study involving exposure of male and female F344 rats to 50 Hz magnetic field strengths of up to 50 G for 2 yr was also negative for any correlation between exposure and cancer incidence (56).…”

Childhood leukemia: electric and magnetic fields as possible risk factors.

“…Using different exposure protocols, Yasui et al (1997) reported no differences in leukemia or lymphoma incidences in rats exposed to either 500 µT or 5,000 µT (5 or 50 G). Likewise, Mandeville et al (1997) reported no effects on the incidence of leukemia in female rats exposed to 2, 20, 200, or 2,000 µT (0.02, 0.2, 2, or 20 G). Finally, Babbitt et al (2000) saw no differences in total hematopoietic neoplasms or lymphomas in female mice exposed to 1,400 µT (14 G) (circularly polarized) EMFs.…”

“…Three large-scale, long-term studies of EMF exposure have been conducted in rats Mandeville et al 1997;Yasui et al 1997) and two in mice (Babbitt et al 2000;McCormick et al 1999). Descriptions and findings from these investigations are summarized in Table 2.…”

Champs magnétiques 50–60 Hz et santé : quoi de neuf ?

“…En expérimentation animale, les études d'initiation (Mandeville et al, 1997 ;Yasui et al, 1997 ;McCormick et al, 1998McCormick et al, , 1999 et de promotion tumorale (Bernard et al, 2008 ;SCENIHR, 2009SCENIHR, , 2013, qui n'ont pas montré d'effet du champ magnétique, s'intègrent dans cette analyse.…”