The Drosophila strain that is genetically sensitive to various mutagens was introduced in order to assess the genotoxic potential of extremely low frequency (ELF) magnetic field. The males of this strain have high sensitivity to mutagens, because they have double mutant alleles, one can't carry out a normal nucleotide excision repair against somatic mutations and the other fail to arrest cell cycle when the replicated chromosome has any aberration. If the males were exposed to mutagen, the fitness of the males would be lower than that of the females owing to accumulation of somatic mutations on single X chromosome. It is possible to estimate the genotoxic potential exposing larvae to the ELF magnetic field during the whole larval development and measuring the male-to-female ratio which would be less than that of the control group, if the genotoxic potential exists. Therefore, we exposed this strain to extremely low frequency (10μT and 100μT) magnetic field, and compared the sex ratio of the exposed groups with that of the control. The result showed that the number of males which were exposed to the 10μT ELF magnetic field reduced by about 5% compared with that of the control, however it was not the statistically significant level. The number of males exposed to the 100μT field significantly reduced by 14%. The numbers of females with two X chromosomes and normal repair genes hardly changed among those of control and exposed groups, but slight decrease (2%) was observed in the number of females exposed to 100μT.
These results suggest that the male X chromosomes in somatic cells that are deficient in two kinds of repair genes could accumulated mutations induced by the mutgenic effect of the extremely low frequency magnetic field.