In Vitro Developmental Neurotoxicity Following Chronic Exposure to 50 Hz Extremely Low-Frequency Electromagnetic Fields in Primary Rat Cortical Cultures

Exposure to 50-60Hz extremely low-frequency electromagnetic fields (ELF-EMFs) has increased considerably over the last decades. Several epidemiological studies suggested that ELF-EMF exposure is associated with adverse health effects, including neurotoxicity. However, these studies are debated as results are often contradictory and the possible underlying mechanisms are unknown. Since the developing nervous system is particularly vulnerable to insults, we investigate effects of chronic, developmental ELF-EMF exposure in vitro. Primary rat cortical neurons received 7 days developmental exposure to 50 Hz block-pulsed ELF-EMF (0-1000 mu T) to assess effects on cell viability (Alamar Blue/FDA assay), calcium homeostasis (single cell fluorescence microscopy), neurite outgrowth (beta(III)-Tubulin immunofluorescent staining), and spontaneous neuronal activity (multi-electrode arrays). Our data demonstrate that cell viability is not affected by developmental ELF-EMF (0-1000 mu T) exposure. Depolarization-and glutamate-evoked increases in intracellular calcium concentration ([Ca2+](i)) are slightly increased at 1 mu T, whereas both basal and stimulation-evoked [Ca2+](i) show a modest inhibition at 1000 mu T. Subsequent morphological analysis indicated that neurite length is unaffected up to 100 mu T, but increased at 1000 mu T. However, neuronal activity appeared largely unaltered following chronic ELF-EMF exposure up to 1000 mu T. The effects of ELF-EMF exposure were small and largely restricted to the highest field strength (1000 mu T), ie, 10 000 times above background exposure and well above current residential exposure limits. Our combined data therefore indicate that chronic ELF-EMF exposure has only limited (developmental) neurotoxic potential in vitro.