Genotoxic hazard evaluation in welders occupationally exposed to extremely low-frequency magnetic fields (ELF-MF)

Genotoxic effects of electromagnetic field radiations from mobile phones

The use of wireless communication technology in mobile phones has revolutionized modern telecommunication and mobile phones have become so popular that their number exceeds the global population. Electromagnetic field radiations (EMR) are an integral part of wireless technology, which are emitted by mobile phones, mobile tower antennas, electric power stations, transmission lines, radars, microwave ovens, television sets, refrigerators, diagnostic, therapeutic, and other electronic devices. Manmade EMR sources have added to the existing burden of natural EMR human exposure arising from the Sun, cosmos, atmospheric discharges, and thunder storms. EMR including radiofrequency waves (RF) and extremely low-frequency radiation (ELF) has generated great interest as their short-term exposure causes headache, fatigue, tinnitus, concentration problems, depression, memory loss, skin irritation, sleep disorders, nausea, cardiovascular effects, chest pain, immunity, and hormonal disorders in humans, whereas long-term exposure to EMR leads to the development of cancer. The review has been written by collecting the information using various search engines including google scholar, PubMed, SciFinder, Science direct, EMF-portal, saferemr, and other websites from the internet. The main focus of this review is to delineate the mutagenic and genotoxic effects of EMR in humans and mammals. Numerous investigations revealed that exposure in the range of 0-300 GHz EMR is harmless as it did not increase micronuclei and chromosome aberrations. On the contrary, several other studies have demonstrated that exposure to EMR is genotoxic and mutagenic as it increases the frequency of micronuclei, chromosome aberrations, DNA adducts, DNA single and double strand breaks at the molecular level in vitro and in vivo. The EMR exposure induces reactive oxygen species and changes the fidelity of genes involved in signal transduction, cytoskeleton formation, and cellular metabolism.

Electromagnetic Fields Change the Expression of Suppressor of Cytokine Signaling 3 (SOCS3) and Cathepsin L2 (CTSL2) Genes in Adenocarcinoma Gastric (AGS) Cell Line

Background: Gastric cancer is one of the most prevalent and deadliest cancers in the world. Environmental factors including chemicals, sunlight, and electromagnetic fields can induce changes in gene expression. Though the resizing mechanism of its effect has not been fully recognized, free radicals are seen as the possible mechanism involved. Although low-frequency electromagnetic fields are not considered a carcinogenic factor, some studies have shown disruption in deoxyribonucleic acid (DNA) and gene expression in different cell categories. Objectives: This study was intendant to examine the effects of low-frequency electromagnetic flux densities of 0.2 and 2 mT on the expression of cathepsin L2 (CTSL2) and suppressor of cytokine signaling 3 (SOCS3) genes in adenocarcinoma gastric (AGS) cell lines. Methods: The AGS cell line was cultured in Hamas12 and was exposed to electromagnetic fields continuously and discontinuously for 18 hours. Moreover, Cell viability was assessed by the MTT (3-(4, 5-Dimethylthiazol-2-yl)) assay. The change in the expression of genes was measured by real-time polymerase chain reaction (PCR). Results: Low-frequency electromagnetic fields increased gene expression compared to the control group. The changes in the expression are directly associated with the electromagnetic field strength. Expression levels of CTSL2 were increased under the exposure of electromagnetic fields and this increase was significant when discontinuous exposure was applied (33.26 ± 7.4 fold change for 0.2mT and 64.4 ± 7.7 for 2mT, p- value

DNA effects of low level occupational exposure to extremely low frequency electromagnetic fields (50/60 Hz)

AIMS

Exposure to extremely low frequency magnetic fields (ELF-MF) occurs from natural and artificial sources. Although ELF-MF has been classified as a suspected humans carcinogen agent by the International Agency for Research on Cancer, little is known of the effects of ELF-MF at lower exposure levels of the recommended range. In the present study, DNA damage in the peripheral blood cells of power line workers was investigated.

MATERIALS AND METHODS

Occupational exposure to ELF-MF in a power plant was measured using the National Institute for Occupational Safety and Health (NIOSH) manual. Single-strand breaks (SSBs) in DNA were evaluated in 29 male utility workers as the exposed population and 28 male support personnel as the control subjects using the comet assay. Effects of ELF-MF on subjects were evaluated using DNA percent in tails, tail length, olive length, and tail moment.

RESULTS

Occupational exposure levels to ELF-MF in the utility workers were less than the threshold limit values (TLV) recommended by the American Conference of Government Industrial Hygienist (ACGIH). The median value of the magnetic field at the working sites was 0.85 µT. Induction of DNA damage was observed for the exposed workers compared with the controls. Olive length, tail moment, and tail DNA percent increased significantly (p < 0.05) in the utility workers.

CONCLUSIONS

Exposure to ELF-MF at levels less than the ACGIH exposure limit can produce DNA strand breaks.

Short-term Exposure to 50-Hz Electromagnetic Field and Alterations in NQO1 and NQO2 Expression in MCF-7 Cells

AIM:

Extremely low-frequency electromagnetic fields (ELF-EMFs) have some genotoxic effects and it may alter the mRNA levels of antioxidant genes. The NAD(P)H: quinone oxidoreductase-1 (NQO1) and NQO2 are ubiquitously expressed. Considering that there is no published data on the effect(s) of ELF-EMF (50-Hz) exposure and expression levels of NQO1 and NQO2 in the human MCF-7 cells, the present study was carried out.

METHODS:

The ELF-EMF (0.25 and 0.50 mT) exposure patterns were: 5 min field-on/5 min filed-off, 15 min field-on/15 min field-off, and 30 min field-on continuously. In all exposure conditions, total exposure time were 30 minutes. The RNA extraction was done at two times; immediately post exposure and two hours post exposure. The effect of ELF-EMF on gene expression was assessed by real-time PCR.

RESULTS:

The NQO1 mRNA level (at 0h) decreased in the cells exposed to 5 min field-on/5 min filed-off condition at 0.25 mT EMF when compared with the unexposed cells. The NQO2 mRNA level (at 0h and 2h) increased in the cells exposed to 5 min field-on/5 min filed-off condition at 0.50 mT EMF when compared with the unexposed cells.

CONCLUSIONS:

Alterations in the NQO1 and NQO2 mRNA levels seem at the “5 min field-on/5 min field-off” condition.

Assessment of genotoxic and cytotoxic hazards in brain and bone marrow cells of newborn rats exposed to extremely low-frequency magnetic field

The present study aimed to evaluate the association between whole body exposure to extremely low frequency magnetic field (ELF-MF) and genotoxic , cytotoxic hazards in brain and bone marrow cells of newborn rats. Newborn rats (10 days after delivery) were exposed continuously to 50 Hz, 0.5 mT for 30 days. The control group was treated as the exposed one with the sole difference that the rats were not exposed to magnetic field. Comet assay was used to quantify the level of DNA damage in isolated brain cells. Also bone marrow cells were flushed out to assess micronucleus induction and mitotic index. Spectrophotometric methods were used to measure the level of malondialdehyde (MDA) and the activity of glutathione (GSH) and superoxide dismutase (SOD). The results showed a significant increase in the mean tail moment indicating DNA damage in exposed group (P < 0.01, 0.001, 0.0001). Moreover ELF-MF exposure induced a significant (P < 0.01, 0.001) four folds increase in the induction of micronucleus and about three folds increase in mitotic index (P < 0.0001). Additionally newborn rats exposed to ELF-MF showed significant higher levels of MDA and SOD (P < 0.05). Meanwhile ELF-MF failed to alter the activity of GSH. In conclusion, the present study suggests an association between DNA damage and ELF-MF exposure in newborn rats.