Unlike the solid scientific and epidemiological bases for the causal relationship between ioniz- ing and UV radiation and the genesis of human cancer, the association of radio frequency, mi- crowave, and visible radiation and magnetic fields with the causation of human cancer has been driven largely by legal, political, and social factors, with little or no scientific and epidemiologi- cal base. Perhaps the initial driving force attempting to relate exposure to such energy fields and long wavelengths was the mere fact that these represented some form of radiation, and some perhaps influential individuals made little or no distinction between such radiation and ionizing and UV radiation. As noted in Chapter 3, this is clearly not correct. Furthermore, Valberg et al. (1997) have argued with sound scientific basis that biological effects in humans from extremely low-frequency electromagnetic fields of the order of those found in residential environments are “implausible based on current understanding of physics and biology.” There is little or no repro- ducible evidence that such radiation and magnetic fields induce any mutational damage to DNA in living cells in a direct manner, such as evident with exposure to ionizing and UV radiation. Furthermore, evidence of overall carcinogenic effects induced by radio frequency and/or micro- wave radiation and magnetic fields is predominantly negative and/or irreproducible (McCann et al., 1998; Kavet, 1996). A more reproducible effect of extremely low frequency (ELF) electro- magnetic fields is on gene transcription in experimental studies, as listed in Table 12.5. Epidemi- ological investigations have in some areas been somewhat more reproducible, although in virtually all reported studies associations reported may well be due to factors and variables not controlled for or even considered in the investigation when one is looking for only a single asso- ciation regardless of other factors (Lacy-Hulbert et al., 1998).
Many scientists in cancer research have viewed the publicity given to the potential of car- cinogenesis by nonionizing, non-UV radiation and magnetic fields as excessive, misleading, and unscientific. However, the effects of electromagnetic fields on specific experimental systems of
Table 12.5 Effects of ELF Electromagnetic Fields on Gene Transcription in Vitro and in Vivo
Adapted from Pitot, 1998, with permission of publisher. See Kaune (1993) for details on units of measurement.
the living cells or organism (Table 12.5) offer the potential that continued chronic exposure of humans and other mammals to such forms of energy may produce altered health effects, of which carcinogenesis is perhaps the least likely.