Involvement of eddy currents in the mutagenicity of ELF magnetic fields

Possible carcinogenic and/or mutagenic activity of extremely low frequency magnetic fields was examined using somatic mutation and recombination test system of Drosophila melanogaster. An X-linked semi-dominant DNA repair def ective mutation mei-41(D5) was introduced into the conventional mwh/flr tes t system to enhance mutant spot frequency. Virgin females of w mei-41(D5)/F M6; flr/TM6 were crossed with w mei-41(D5)/Y; mwh jv; spa(pol) males. The F -1 third instar larvae were exposed to a 50 Hz, 20 mT sinusoidal AC magneti c field for 24 h. After moulting from pupal cases, their wings were examine d under a bright field microscope to detect hair spots with mwh or flr muta nt morphology. The exposure caused a statistically significant enhancement in somatic recombination spot frequency. Mutant spots arising due to chromo somal non-disjunction or terminal deletion also increased but the frequency of spots resulting from point mutation was not altered. The enhancement in the recombination spot frequency was suppressed to the control level when a culture medium without electrolytes was used during exposure. When larvae were exposed to a magnetic field in an annular dish, flies from the outer ring showed more mutant spots compared to those from the inner ring. These results suggest that the detected mutagenic activity was that of the induce d eddy current, rather than that of the magnetic field itself. (C) 2001 Els evier Science B.V. All rights reserved.