Negative effects on a bioindicator by electromagnetic field exposures alone and in combination with UVC rays

Genotoxic effects of radiofrequency (RF)/microwave (MW) electromagnetic fields, by using s tandard protocol of single cell gel electrophoresis (SCGE) or comet assay, were investigated in the coelomocytes of the bioindicator Eisenia fetida exposed to both laboratory and field experiments. In particular, laboratory treatments were performed by a TEM microstrip (900MHz – 0.20mW/Kg) to reproduce the characteristics of the waves generated by RF anthropic sources found on field. In order to assess the potential oxidative damage caused by microwave electromagnetic exposure, two base excision repair enzymes, i.e. endonuclase III (Endo III) and formamidopyrimidine DNA glycosylase (FPG) were used in combination with a modified comet assay protocol. In addition, DNA fragmentation of combinative exposure of ultraviolet rays C (UVC) alone and in combination with microwaves was also studied; in order to assess the influence of electromagnetic fields on DNA repair mechanisms of UVC, T4 endonuclease V (T4PDG) enzyme, which specifically induces single-stranded breaks in ultraviolet-irradiated DNA, was used. Finally, a fieldwork was conducted in three electromagnetic hot-spots in the city of Milan, Italy; in addition, a negative control site with a low electromagnetic field intensity was considered. Loss of DNA integrity was detected by using two main comet assay parameters, i.e. Tail Moment (TM) and Tail Moment Olive (TMO). Data showed an initial increase in TM and TMO (expressed as differences between Tail Moment or Tail Moment Olive from exposed and respective controls averages) after EMF treatments, resulting the highest after the first minutes of recovery ( TM: 6.63±0.70, immediately after exposure and TMO: 4.43±0.38, after 30 minutes, respectively). However, a transient genotoxic damage was observed at 2 hours from exposure (p<0.01). The results, after adding EndoIII and FPG, showed higher values of TM after the combinative treatment with the two repair enzymes compared with microwave exposure (p<0.05) at all times of recovery. Concerning UVC exposure, we observed the highest value of TM after 1 hour from the exposure (5.94±0.42) and a significant diminish after 2 hours (1.73±0.33). In addition, T4 endonuclease V was able to increase the number of breaks after the exposure to UVC radiation at t0, for the damage was approximately four-fold the level of breaks from ultraviolet radiation alone ( TM of 3.42±0.36 and 13.88±1.61, respectively). The combinative effect of UVC and microwave exposure showed significant lower levels of DNA damage than those of corresponding UVC groups at 1 hour of recovery (3.02±0.26 and 5.91±0.54, p<0.01 for TM, respectively). However, DNA fragmentation from UVC plus radiofrequency treatments was significantly higher (p<0.05) than those of the corresponding UVC groups for the following times of recovery. T4PDG did not affect MW-induced DNA breaks (p>0.05); conversely, the action of the repair enzyme was affected by the presence of RF after UV exposure, because TM, after the combinative exposure of the two physical agents, resulted lower than that found by adding T4 Endonuclease V after ultraviolet rays exposure alone (p<0.05). Finally, field exposures revealed a significant difference between negative controls and exposed animals in all the hot spots (p<0.01); a positive correlation (p<0.001, R2 =0.56) between electric values and genotoxic parameters was found and no relationship between DNA damage and other environmental parameters, considered under field conditions, was observed