Evaluation of DNA damage in lymphocytes of radiology personnel by comet assay

Effects of low-dose ionizing radiation on genomic instability in interventional radiology workers

Interventional radiologists are chronically exposed to low-dose ionizing radiation (IR), which may represent a health risk. The aim of the present study was to evaluate genomic instability by analyzing chromosomal aberrations, micronuclei, and 53BP1 DNA repair foci in peripheral blood lymphocytes of radiologists. Based on the IAEA guidelines on biodosimetry using dicentrics, the average protracted whole-body dose in radiologists were estimated. Since preleukemic fusion genes (PFG) are the primary events leading to leukemia, we also studied their presence by RT-qPCR and FISH. No significant difference in 53BP1 foci and incidence of PFG (MLL-AF4, MLL-AF9, AML1-ETO, BCR-ABL p190) was found in cells of interventional radiologists in comparison to controls. However, our results showed an increased frequency of micronuclei and various types of chromosomal aberrations including dicentrics in interventional radiologists. The average protracted whole body estimated dose was defined at 452.63 mGy. We also found a significantly higher amplification of the MLL gene segment and increased RNA expression in cells of interventional radiologists in comparison to controls. In conclusion, our results showed that long-term low-dose IR induces genomic instability in interventional radiologists.

Effect of simultaneous exposure to inhalational anesthetics and radiation on the adaptive response in operating room personnel

Some operating room personnel, such as orthopedic surgeons, are exposed simultaneously to inhalational anesthetics (IAs) and radiation that both can cause DNA damage. Some studies have shown that low doses of radiation reduce DNA damage when the cells are followed by a higher dose of the same or related agent. This study, therefore, set out to compare DNA damage in the anesthesiologists, radiologists, orthopedic surgeons, and healthcare staff (non-exposed group). In this cross-sectional study, breathing zone concentrations of anesthetic gas nitrous oxide (N₂O) were measured in the studied groups using standard method. Additionally, DNA damage was measured by micronucleus (MN) assay. The mean concentrations of N₂O in the anesthesiologists and orthopedic surgeons were 450.27 ± 327.44 ppm and 313.64 ± 216.14 ppm, respectively. The mean annual exposure to X-rays radiation in radiologists and orthopedic surgeons was 15.65 ± 8.46 mSy/year and 3.56 ± 1.32 mSy/year, respectively. MN frequencies were significantly higher in anesthesiologists and radiologists exposed to IAs and X-rays radiation respectively than in the non-exposed healthcare staff. While, there were no statistically significant differences between MN frequencies of orthopedic surgeons exposed to both IAs and radiation and healthcare staff. These findings suggest that an earlier exposure of orthopedic surgeons to a small dose of ionizing radiation can increase their resistance to genotoxicity caused by high doses of N₂O, a phenomenon that is called adaptive response.

Biomarkers of Genotoxicity in Medical Workers Exposed to Low-Dose Ionizing Radiation: Systematic Review and Meta-Analyses

Medical staff represent the largest group of workers occupationally exposed to ionizing radiation (IR). Chronic exposure to low-dose IR may result in DNA damage and genotoxicity associated with increased risk of cancer. This review aims to identify the genotoxicity biomarkers that are the most elevated in IR-exposed vs. unexposed health workers. A systematic review of the literature was performed to retrieve relevant studies with various biomarkers of genotoxicity. Subsequent meta-analyses produced a pooled effect size for several endpoints. The search procedure yielded 65 studies. Chromosome aberrations (CA) and micronuclei (MN) frequencies were significantly different between IR-exposed and unexposed workers (θ_pooled = 3.19, 95% CI 1.46–4.93; and θ_pooled = 1.41, 95% CI 0.97–1.86, for total aberrant cells and MN frequencies, respectively), which was not the case for ring chromosomes and nucleoplasmic bridges. Although less frequently used, stable translocations, sister chromatid exchanges (SCE) and comet assay endpoints were also statistically different between IR-exposed and unexposed workers. This review confirms the relevance of CA and MN as genotoxicity biomarkers that are consistently elevated in IR-exposed vs. unexposed workers. Other endpoints are strong candidates but require further studies to validate their usefulness. The integration of the identified biomarkers in future prospective epidemiological studies is encouraged.

Scalp Hair Metal Analysis Concerning DNA Damage in Welders of Peshawar Khyber Pakhtunkhwa Pakistan

Welding is used throughout the world in refineries, thermal power plants, chemical facilities, and pressurized containers, and the welders are exposed to toxic heavy metals, electromagnetic fields, polycyclic aromatic hydrocarbon, and ultraviolet radiations. In the present study, 59 welders and an equal number of control subjects were assessed for DNA damage in the lymphocytes using the comet assay. Heavy metals such as lead (Pb), iron (Fe), nickel (Ni), chromium (Cr), manganese (Mn), and cadmium (Cd) levels in the scalp hair of the subjects were evaluated by using atomic absorption spectroscopy (AAS). The results of the current study showed that DNA damage in the lymphocytes of welders (121.8 ± 10.7) was significantly higher as compared with controls (56.5 ± 17.6) (P < 0.001). Besides, the levels of Pb, Fe, Ni, Cr, Mn, and Cd were remarkably higher in the scalp hair of workers as compared with the control group (P < 0.001). Regression analysis showed a prominent association between the heavy metals and total comet score (TCS) in the exposed subjects. Age and duration of occupational exposure had significant effects (P < 0.05) on TCS values. Our results concluded that occupational exposure to welding fumes may cause DNA damage and can lead to important health hazards in the workers.

Gasoline-station workers in Brazil: Benzene exposure; Genotoxic and immunotoxic effects

Chronic exposure to benzene is a risk factor for hematological malignancies. Gasoline-station workers are exposed to benzene in gasoline, via both inhalation and dermal contact (attendants and managers) or inhalation (workers in the on-site convenience stores and offices). We have studied the exposure of these workers to benzene and the resulting genotoxic and immunotoxic effects. Levels of urinary trans, trans-muconic acid were higher among gasoline-station workers than among office workers with no known exposure to benzene (comparison group). Among the exposed workers, we observed statistically significant biological effects, including elevated DNA damage (comet assay); higher frequencies of micronuclei and nuclear buds (CBMN assay); lower levels of T-helper lymphocytes and naive Th lymphocytes; lower CD4 / CD8 ratio; and higher levels of NK cells and memory Th lymphocytes. Both groups of exposed workers (inhalation and inhalation + dermal routes) showed similar genotoxic and immunotoxic effects.

Biomonitoring of DNA Damage in Photocopiers' Workers From Peshawar, Khyber Pakhtunkhwa, Pakistan

OBJECTIVES

The study was performed to know about the extent of occupational DNA damage in photocopiers' workers.

METHODS

Blood samples were collected from 136 exposed group and 74 control group. Comet assay was performed to assess the DNA damage caused by emissions from photocopiers.

RESULTS

The results indicated that there was a significant increase (P < 0.05) in DNA damage in persons working in photocopiers (122.1 ± 60.7) than the controls (56.6 ± 17.2). Duration of occupational exposure had positive correlation (r = 0.793, P < 0.001) with DNA damage. Age had significant effects on the total comet score (TCS) of the exposed group as compared to the control group (P < 0.05).

CONCLUSIONS

In conclusion, these findings indicate significant genotoxicity in photocopiers' workers.

Polymorphism in GSTM1 and GSTT1 genes influence DNA damage in personnel occupationally exposed to volatile anaesthetics (VA), from Peshawar, Pakistan

Objectives

The objective of this study was to assess the influence of antioxidant gene GSTM1 and GSTT1 on DNA damage in personnel occupationally exposed to volatile anaesthetics (VA).

Methods

The study groups were composed of 50 exposed subjects (anaesthesia workers) and 49 controls. Blood samples were collected from both subjects. DNA damage was analysed through the comet assay technique. Biomarker genes GSTM1 and GSTT1 were inspected through PCR technique for polymorphism.

Results

The comet assay technique showed that the Total Comet Score (TCS) in exposed subjects was significantly higher (p=0.0001) than the control. Age and smoking had significant effects on TCS in the study groups (p<0.05). Duration of occupational exposure had significant positive correlation (r=0.755, p<0.001) with DNA damage. The null polymorphism in GSTM1 and GSTT1 gene showed a significant effect (p<0.001 and p<0.000) on the DNA damage.

Conclusions

The polymorphism in GSTM1 and GSTT1 gene significantly damage DNA in personnel occupationally exposed to VA.

Smoking index, lifestyle factors, and genomic instability assessed by single-cell gel electrophoresis: a cross-sectional study in subjects from Yucatan, Mexico

BACKGROUND

It is widely accepted that genomic instability is associated with several mechanisms involving oxidative stress, which can increase the rate of DNA breaks. Such factors include smoking, impairments in body composition, an unhealthy lifestyle, and a hereditary history of cancer. The aim was to evaluate the degree of association of genomic instability in smokers and non-smokers, and how the risk could change depending on the lifestyle and other causes. For this purpose, a survey of tobacco consumption, dietary patterns, physical activity, antecedents of cancer, and body composition assessment was carried out. Genomic instability was evaluated through a single-cell gel electrophoresis using peripheral blood mononuclear cells in three different conditions of oxidative stress. The analysis of genomic damage degree was performed through a dimension reduction procedure (principal component analysis) from 16 parameters per treatment (adding up 48 parameters of genomic damage per subject) and a binary logistic regression model for DNA fragmentation risk.

RESULTS

The sample consisted of 82 participants, divided into three age groups: young adults (18-35 years), adults (36-59 years), and older adults (60-95 years). As expected, the results showed a significant positive correlation of age with genomic damage rates, represented by 2 PCA groups (p = 0.027, p = 0.004). There were consistent significant positive associations of genomic damage rates with smoking index and three PCA groups (p = 0.007, p = 0.004, p = 0.009). The smoking status and age group analysis revealed that there were significant differences for adult smokers with the same aforementioned PCA groups (p = 0.002, p = 0.001, p = 0.010). In addition, higher DNA damage rates were found in subjects with incorrect diet patterns, long sitting hours, and previous exposure to radiation. The analysis with binary logistic regression displayed two models in which lifestyles (age, diet, and/or sedentarism) did not change the significance of smoking index for DNA fragmentation risk; however, when physical activity was present in the model, the smoking index was not a significant factor for DNA damage risk.

CONCLUSIONS

Although it is well known that smoking affects human health in different ways, DNA fragmentation can be analyzed by a damage phenotypic analysis and integrate a risk analysis reshaped by diet and lifestyle in general.

Absence of mutations in the human interferon alpha-2b gene in workers chronically exposed to ionising radiation

Individuals chronically exposed to low-level ionising radiation (IR) run the risk of harmful and long-term adverse health effects, including gene mutations and cancer development. The search for reliable biomarkers of IR exposure in human population is still of great interest, as they may have a great implementation potential for the surveillance of occupationally exposed individuals. In this context, and considering previous literature, this study aimed to identify mutations in the human interferon alpha-2b (hIFNα-2b) as a potential biomarker of occupational chronic low-dose IR exposure linking low-IR exposure to the effects on haematopoiesis and reduced immunity. The analysis was performed in the genomic DNA of 51 uranium miners and 38 controls from Kazakhstan, and in 21 medical radiology workers and 21 controls from Italy. hIFNα-2b gene mutations were analysed with the real-time polymerase chain reaction (PCR) or Sanger sequencing. However, none of the investigated workers had the hIFNα-2b mutation. This finding highlights the need for further research to identify biomarkers for early detection of health effects associated with chronic low-dose IR exposure.

Bioaccumulation of Heavy Metals and their Genotoxic Effect on Freshwater Mussel

Contamination of fresh water bodies like riverine system is utmost concerned environmental issue. This study was aimed to assess the concentration of heavy metals in River Kabul and their bioaccumulation by freshwater mussel. Comet assay was used to evaluate the genotoxic effect of heavy metals on hemocytes of freshwater mussel. The concentration of heavy metals in water was in the order of Zn > Pb > Ni > Cu > Mn > Fe > Cr > Cd, in sediments were Fe > Zn > Cr > Ni > Mn > Pb > Cu > Cd and in the soft tissues of freshwater mussel were in order of Fe > Zn > Mn > Pb > Cu > Cr > Ni > Cd. The hemocytes of mussels from polluted sites showed significantly higher (p < 0.05) DNA damage as compared to reference site. The study showed that pollutants from industries, municipal, domestic and agricultural sources cause heavy metals contamination in River Kabul.

Bio-monitoring of DNA damage in matchstick industry workers from Peshawar Khyber Pakhtunkhwa, Pakistan

BACKGROUND

Safety protocols are usually neglected in most of the matchstick industries rendering the laborer prone to various occupational hazards.

OBJECTIVE

The present study highlights DNA damage among matchstick factory workers (n = 92) against a control group (n = 48) of healthy individuals.

METHODS

Genotoxicity was measured in peripheral blood lymphocytes of the test subjects using a Single Cell Gel Electrophoresis assay (SCGE/comet assay).

RESULTS

Our results substantiate a high Total Comet Score (TCS) for factory workers (74.5 ± 47.0) when compared to the control group (53.0 ± 25.0) (P ≤ 0.001). Age and duration of occupational exposure had no significant effect (P > 0.05) on TCS value. As for job function, the TCS value was greatest in sweepers (91.0 ± 56.1) and lowest in box-making operators (26.0 ± 25.0) indicating that waste disposal poses the higher risk of DNA damage.

CONCLUSIONS

Our study corroborates that matchstick chemicals can potentially damage the DNA of exposed subjects.

Bio-monitoring of Tissue Accumulation and Genotoxic Effect of Heavy Metals in Cyprinus carpio from River Kabul Khyber Pakhtunkhwa Pakistan

The study explored (I) the concentration of heavy metals in water samples (II) their bioaccumulation in common carp Cyprinus carpio (III) and the subsequent genotoxicity in the selected organs of carp; from river Kabul, Khyber Pakhtunkhwa Pakistan. Except for Mercury (Hg) the water samples had all the heavy metals within permissible limits of recommended dietary allowance (RDA). Nonetheless a number of heavy metals (Zn, Ni, Cr, Cd, Pb and Hg) showed bioaccumulation at levels higher than permissible. Zinc (Zn) was the most while Cadmium (Cd) was the least accumulated metal in all tissue samples analyzed. The metal burden in different organs of C. carpio was in sequence of intestine > skin > liver > gills > muscle. The Comet assay established DNA damage in selected organs to be in accordance with metal burden; the most to least damage being in sequence of blood > intestine > skin > liver > gills > muscle. In conclusion assessment of DNA damage in the organs of C. carpio appears to be a useful bio-marker to evaluate genotoxic effects of heavy metal pollution.