Assessing the Potential Carcinogenic Activity of Magnetic Fields Using Animal Models

Abstract

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.

Population-Based Case-Control Study of Occupational Exposure to Electromagnetic Fields and Breast Cancer

“…Given that the referent group was not working at all, and the absence of dose-response gradients, it seems unlikely that exposure to EMFsplayed a role in the lower risk experienced by the referent group. In addition, the time period of 10-20 years between exposure and diagnosis could .be considered inconsistent with the hypothesis that exposure to EMFs acts as a rumor promotor (26,27), which would predict that relevant exposure to EMFs would be close in time to diagnosis. Exposure levels experienced in this study population are considerably lower than those encountered by electric utility workers (45), and may well have been too low to detect moderately increased breast cancer risks if any truly exist.…”

“…The time windows were chosen to consider possible latency of the effect of magnetic field exposure on breast cancer, and to evaluate the hypothesis that magnetic field exposure has a tumor promoting effect (26,27).…”

Magnetic field exposure and long-term survival among children with leukaemia

“…However, in vitro studies and in vivo animal experiments have not produced evidence of adverse effects at or near the MF levels associated with residential environments, nor has a biophysical basis for such effects been established (NIEHS, 1998;McCann et al, 2000). While earlier studies have examined potential effects of MF exposure on leukaemia incidence, MF research has not focused on the progress of disease.…”

Influence of a 50 Hz magnetic field and of all-trans‑retinol on the proliferation of human cancer cell lines

“…However, in the lack of adequate knowledge on the mechanism through which these fields might intervene in cancer processes, the international standards for non-ionizing radiation protection have considered the epidemiological evidence as non demonstrative. In fact, the current experimental evidence on in vivo responses to magnetic flux densities (B) below 500 µT, which corresponds to the reference level for protection of workers against potential harmful effects of short-term exposure to 50 Hz MF (7,8), has been repeatedly described as scarce and limited (9,10). Similarly, the results of in vitro studies investigating potential effects of weak MF on cell proliferation are considered inconsistent altogether [see Santini et al (11) for a review] due in part to the fact that a number of physical (magnetic flux density, exposure time, exposure cycle) and biological factors (cell type, cell genetics and/or cell physiology) seem to be critical to the cellular response (12,13).…”