Abstract
The potential health risks of extremely low frequency (ELF) magnetic fields are a public
concern. Investigations of the potential relationship(s) with human health are very important, and
many studies have been sought to elucidate the biological effects of ELF magnetic fields. Once, most
investigations have evaluated the effects of ELF magnetic field alone. In 2007, the World Health
Organization (WHO) with their Task Group concluded that ELF magnetic field alone have no
carcinogenic potential and recommended that further investigations include the evaluation of the
combined carcinogenic effects of ELF magnetic field in vitro. Ultraviolet (UV) irradiation can affect
many kinds of cellular targets, including nucleic acids, proteins and lipids. DNA is the most important
target of UV irradiation. In this study, we evaluated the combined effects of ELF magnetic field
exposure on cell survival and DNA damage induced by UV irradiation
The ELF magnetic field exposure was conducted with a Helmholtz coil-based exposure
system, which was designed to generate a sinusoidal magnetic field at 5 millitesla (mT) and 50/60 Hz.
UV irradiation was performed with specially designed apparatus with five UV-Clamps (mainly 253.7
nm) at room temperature.
Human embryo lung-derived SV40 virus transformed WI38VA13 subclone 2RA cells were
cultured in Eagle's minimum essential medium with non-essential amino acids, lmM sodium pyruvate
and 10% fetal bovine serum (FBS). Human xeroderma pigmentosum (valiant type )-derived XP2SA
cells were cultured in Dulbecco's modified Eagle's medium with 10% FBS. The cell survival, DNA
synthesis and DNA damage were assessed by WST assay, IdU assay and quantification of cyclobutane
pyrimidine dimer formation with ELISA method, respectively. WI38VA13 subclone 2RA cells were
exposed to magnetic field at 5 mT and 50/60 Hz for 24 hours before/after UV irradiation at 0, 2, 4, 6
and 8 J/m2
• XP2SA cells were analyzed as described for the WI38V A 13 subclone 2RA cells, except
that UV irradiation was performed at 0.5, 1, 1.5 and 2 J/m2 for cell survival assay and DNA synthesis
assay, and 1, 2, 3 and 4 J/m2 for DNA damage assay.
No significant differences were observed in cell survival between ELF magnetic field and
sham exposures. Similarly, DNA damages induced by UV irradiation were not changed significantly
by ELF magnetic field exposure. Our results suggest that ELF magnetic field exposure at 5 mT does
not affect cell survival and DNA damage induced by UV irradiation.
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