Lymphoblastoid Cells Exposed to Low-Frequency Magnetic Fields: Study by Atomic Force Microscopy

Since the appearance of the first pioneering article in the 1970s, particular efforts have been made to study the effect of exposure to electric and magnetic fields (EMFs) on living matter (1 –10 ). The initial interest in radio frequency and microwaves has shifted to include the nonthermal, and essentially magnetic, effect of extremely low frequencies (ELF, 1–300 Hz), in particular the 50 and 60 Hz of the electric power system (3 ,4 ,9 ). The density of normal ELF fields is usually below 0.1 μT, but values of 0.5 μT may be found in front of television sets and computer monitors (11 ) as well as at a distance of 50 m from 300-kV high-voltage power lines (12 ). Values up to two to three orders of magnitude higher can be found near some domestic appliances or in some industrial processes, and pulsed magnetic fields in the range 1–10 mT are used in nuclear magnetic resonance imaging and for the therapy of soft tissue or nonhealing bone fractures (1 ).The increasing interest in ELF fields has been partially motivated by epidemiological reports of an increase in some types of cancer and leukemia in children (13 ,14 ) and workers exposed to high levels of ambient fields. Carcinogenesis is considered to be a multistep process consisting of initiation-promotion-progression stages (15 ). Although ELF magnetic fields are not considered sufficiently energetic to interact with DNA and initiate a cancerous process, they could, by acting on cellular receptors, affect cell proliferation and modulate the promotion or progression stage.