Cellular detection of 50Hz magnetic fields and weak blue light: effects on superoxide levels and genotoxicity

Purpose: We tested the hypothesis that the effects of 50Hz magnetic fields (MFs) on superoxide levels and genotoxicity depend on the presence of blue light.Materials and methods: Human SH-SY5Y neuroblastoma cells were exposed to a 50Hz, 100T MF with or without non-phototoxic level of blue light for 24h. We also studied whether these treatments alter responses to menadione, an agent that induces mitochondrial superoxide (O-2(center dot -)) production and DNA damage. Micronuclei, proliferation, viability, cytosolic and mitochondrial O-2(center dot -) levels were assessed.Results: MF (without blue light) increased cytosolic O-2(center dot -) production and blue light suppressed this effect. Mitochondrial O-2(center dot -) production was reduced by both MF and blue light, but these effects were not additive. Micronucleus frequency was not affected by blue light or MF alone, but blue light (significantly when combined with MF) enhanced menadione-induced micronuclei.Conclusions: The original simple hypothesis (blue light is needed for MF effects) was not supported, but interaction of MF and blue light was nevertheless observed. The results are consistent with MF effects on light-independent radical reactions.