Paramjit Grover

DNA damage in workers exposed to lead using comet assay.

Lead (Pb) is a ubiquitous and toxic metal. Secondary Pb recovery unit workers are prone to possible occupational Pb exposure. Hence, this investigation was conducted to assess the genotoxic effect of Pb exposure in these workers. In the study, 45 workers were monitored for DNA damage in blood leucocytes. Simultaneously 36 subjects were used as control group in this study. All the subjects were estimated for Pb content in whole blood by ICP-MS. The alkali single cell gel electrophoresis assay (comet assay) was adopted for detecting the DNA damage. The air inside the premises of the unit had Pb concentrations of 4.2 microg/m(3). The level of DNA damage was determined as the percentage of cells with comets. The mean Pb content was found to be significantly higher in the study group (248.3 microg/l) when compared with the controls (27.49 microg/l). Significantly more cells with DNA damage (44.58%) were observed in the study group than in the control persons (21.14%). Smoking had a significant effect on DNA damage in the control group whereas an insignificant effect was noticed in the exposed workers. Study as well as the control group failed to show a significant effect on DNA damage with age (P>0.05). Pb content and years of exposure significantly correlated with DNA damage in the study group (r=0.602, r=0.690; P<0.01). The increased levels of DNA damage observed in the exposed workers, justifies the use of the comet assay for the evaluation of genotoxic effects in humans exposed to Pb.

Assessment of genotoxic effects of chloropyriphos and acephate by the comet assay in mice leucocytes.

Two organophosphorus (OP) pesticides (chloropyriphos and acephate) and cyclophosphamide (CP) (positive control) were tested for their ability to induce in vivo genotoxic effect in leucocytes of Swiss albino mice using the single cell gel electrophoresis assay or comet assay. The mice were administered orally with doses ranging from 0.28 to 8.96 mg/kg body weight (b. wt.) of chloropyriphos and 12.25 to 392.00 mg/kg b.wt. of acephate. The assay was performed on whole blood at 24, 48, 72 and 96 h. A significant increase in mean comet tail length indicating DNA damage was observed at 24h post-treatment (P<0.05) with both pesticides in comparison to control. The damage was dose related. The mean comet tail length revealed a clear dose dependent increase. From 48 h post-treatment, a gradual decrease in mean tail length was noted. By 96 h of post-treatment the mean comet tail length reached control levels indicating repair of the damaged DNA. From the study it can be concluded that the comet assay is a sensitive assay for the detection of genotoxicity caused by pesticides.

Semen quality of Indian welders occupationally exposed to nickel and chromium

The semen quality of 57 workers from a welding plant in South India and 57 controls was monitored. Blood nickel and chromium concentrations were determined by ICP-MS. Analysis of semen samples was performed in accordance with World Health Organization criteria. The blood level of nickel and chromium for the 28 exposed workers was 123.3 +/- 35.2 and 131.0 +/- 52.6 microg/l, resepctively, which was significantly higher than the 16.7 +/- 5.8 and 17.4 +/- 8.9 microg/l for the control group (n=27). Sperm concentrations of exposed workers were 14.5 +/- 24.0 millions/ml and those of the control group were 62.8 +/- 43.7 millions/ml. Rapid linear sperm motility was decreased in exposed workers compared to controls. There was a significant positive correlation between the percentage of tail defects and blood nickel concentration in exposed workers. The sperm concentration showed a negative correlation with blood chromium content in workers. More abnormal characteristics were found in the semen of exposed workers. Semen abnormalities correlated with the number of years of exposure to welding fumes containing nickel and chromium.

Genotoxicity evaluation in workers occupationally exposed to lead

Lead (Pb) is a widely used heavy metal with a broad industrial usage. Nevertheless, Pb is a serious public health issue as it is one of the most widespread environmental and industrial toxins. The aim of this investigation was to assess the genotoxicity of Pb using the comet assay, micronucleus (MN) and chromosomal aberrations (CA) test. Blood and urinary Pb content, levels of delta-aminolevulinic acid dehydratase in the erythrocytes (E-ALAD) and delta-aminolevulinic acid in urine (U-ALA) were determined. The exposure associated oxidative stress was also studied. The study group comprised of 90 male Pb recovery unit workers and 90 matched controls. The results indicated that the exposed workers had a significantly higher mean comet tail length than that of controls (P<0.05). Analysis of micronuclei in buccal epithelial cells (BECs) and peripheral blood lymphocytes (PBL) revealed that there was a significant increase in frequency of MN in exposed subjects than controls. The frequency of aberrant metaphases was also found to be significantly elevated in the Pb exposed workers. The levels of antioxidant enzymes were relatively reduced (P>0.05) while the rate of lipid peroxidation was higher in the exposed subjects. Blood and urinary Pb concentrations were found to be higher in exposed workers than in controls. E-ALAD levels were reduced and U-ALA levels were elevated in the exposed subjects in comparison to controls. Results of analysis, taking the confounding factors into consideration provide evidence for the association of Pb exposure and genotoxicity, and predict the increased risk of cancer to the exposed workers. In view of the observed results, it can be strongly concluded that the workers comprise the risk group and adequate safety, precautionary and preventive measures could only minimize exposure and the related health hazards.

In vivo genotoxicity assessment of aluminium oxide nanomaterials in rat peripheral blood cells using the comet assay and micronucleus test

Advances in nanotechnology and its usage in various fields have led to the exposure of humans to engineered nanomaterials (NMs) and there is a need to tackle the potential human health effects before these materials are fully exploited. The main purpose of the current study was to assess whether aluminium oxide NMs (Al(2)O(3)-30 nm and Al(2)O(3)-40 nm) could cause potential genotoxic effects in vivo. Characterization of Al(2)O(3)-30 nm and Al(2)O(3)-40 nm was done with transmission electron microscopy, dynamic light scattering and laser Doppler velocimetry prior to their use in this study. The genotoxicity end points considered in this study were the frequency of micronuclei (MN) and the percentage of tail DNA (% Tail DNA) migration in rat peripheral blood cells using the micronucleus test (MNT) and the comet assay, respectively. Genotoxic effects were evaluated in groups of female Wistar rats (five per group) after single doses of 500, 1000 and 2000 mg/kg body weight (bw) of Al(2)O(3)-30 nm, Al(2)O(3)-40 nm and Al(2)O(3)-bulk. Al(2)O(3)-30 nm and Al(2)O(3)-40 nm showed a statistically significant dose-related increase in % Tail DNA for Al(2)O(3)-30 nm and Al(2)O(3)-40 nm (P < 0.05). However, Al(2)O(3)-bulk did not induce statistically significant changes over control values. The MNT also revealed a statistically significant (P < 0.05) dose-dependent increase in the frequency of MN, whereas Al(2)O(3)-bulk did not show any significant increase in frequency of MN compared to control. Cyclophosphamide (40 mg/kg bw) used as a positive control showed statistically significant (P < 0.001) increase in % Tail DNA and frequency of MN. The biodistribution of Al(2)O(3)-30 nm and Al(2)O(3)-40 nm and Al(2)O(3)-bulk in different rat tissues, urine and feces was also studied 14 days after treatment using inductively coupled plasma mass spectrometry. The data indicated that tissue distribution of Al(2)O(3) was size dependent. Our findings suggest that Al(2)O(3) NMs were able to cause size- and dose-dependent genotoxicity in vivo compared to Al(2)O(3)-bulk and control groups.

Comparative study of genotoxicity and tissue distribution of nano and micron sized iron oxide in rats after acute oral treatment.

Though nanomaterials (NMs) are being utilized worldwide, increasing use of NMs have raised concerns over their safety to human health and environment. Iron oxide (Fe(2)O(3)) NMs have important applications. The aim of this study was to assess the genotoxicity of Fe(2)O(3)-30nm and Fe(2)O(3)-bulk in female Wistar rats. Fe(2)O(3)-30nm was characterized by using transmission electron microscopy, dynamic light scattering, laser Doppler velocimetry and surface area analysis. The rats were treated orally with the single doses of 500, 1000, 2000mg/kg bw of Fe(2)O(3)-30nm and Fe(2)O(3) -bulk. The genotoxicity was evaluated at 6, 24, 48 and 72h by the comet assay in leucocytes, 48 and 72h by micronucleus test (MNT) in peripheral blood cells, 18 and 24h by chromosomal aberration (CA) assay and 24 and 48h by MNT in bone marrow cells. The biodistribution of iron (Fe) was carried out at 6, 24, 48 and 72h after treatment in liver, spleen, kidney, heart, brain, bone marrow, urine and feces by using atomic absorption spectrophotometry. The % tail DNA, frequencies of micronuclei and CAs were statistically insignificant (p>0.05) at all doses. These results suggest that Fe(2)O(3)-30nm and Fe(2)O(3)-bulk was not genotoxic at the doses tested. Bioavailability of Fe was size and dose dependent in all the tissues from the groups exposed to Fe(2)O(3)-30nm. Fe(2)O(3) NMs were able to enter in the organs and the rats are biocompatible with much higher concentration of Fe. However, the accumulated Fe did not cause significant genotoxicity. This study provides additional knowledge about the toxicology of Fe(2)O(3) NMs.

Evaluation of genotoxic effects of oral exposure to aluminum oxide nanomaterials in rat bone marrow.

Nanomaterials have novel properties and functions because of their small size. The unique nature of nanomaterials may be associated with potentially toxic effects. The aim of this study was to evaluate the in vivo genotoxicity of rats exposed with Aluminum oxide nanomaterials. Hence in the present study, the genotoxicity of Aluminum oxide nanomaterials (30 and 40 nm) and its bulk material was studied in bone marrow of female Wistar rats using chromosomal aberration and micronucleus assays. The rats were administered orally with the doses of 500, 1000 and 2000 mg/kg bw. Statistically significant genotoxicity was observed with Aluminum oxide 30 and 40 nm with micronucleus as well as chromosomal aberration assays. Significantly (p < 0.05 or p < 0.001) increased frequency of MN was observed with 1000 and 2000 mg/kg bw dose levels of Aluminum oxide 30 nm (9.4 +/- 1.87 and 15.2 +/- 2.3, respectively) and Aluminum oxide 40 nm (8.1 +/- 1.8 and 13.9 +/- 2.21, respectively) over control (2.5 +/- 0.7) at 30 h. Likewise, at 48 h sampling time a significant (p < 0.05 or p < 0.001) increase in frequency of MN was evident at 1000 and 2000 mg/kg bw dose levels of Aluminum oxide 30 nm (10.6 +/- 1.68 and 16.6 +/- 2.66, respectively) and Aluminum oxide 40 nm (9.0 +/- 1.38 and 14.7 +/- 1.68, respectively) compared to control (1.8 +/- 0.75). Significantly increased frequencies (p < 0.05 or p < 0.001) of chromosomal aberrations were observed with Aluminum oxide 30 nm (1000 and 2000 mg/kg bw) and Aluminum oxide 40 nm (2000 mg/kg bw) in comparison to control at 18 and 24 h. Further, since there is need for information on the toxicokinetics of nanomaterials, determination of these properties of the nanomaterials was carried out in different tissues, urine and feces using inductively coupled plasma mass spectrometry (ICP-MS). A significant size dependent accumulation of Aluminum oxide nanomaterials occurred in different tissues, urine and feces of rats as shown by ICP-MS data. The results of our study suggest that exposure to Aluminum oxide nanomaterials has the potential to cause genetic damage.

Genotoxic effect of lead nitrate on mice using SCGE (comet assay).

Single stranded DNA breakage induced by lead nitrate in mice has been studied in vivo using alkaline single cell gel electrophoresis (comet assay). Mice were administered orally 0.7, 1.4, 2.8, 5.6, 11. 2, 22.4, 44.8 and 89.6 mg/kg body weight of lead nitrate and the assay was performed on whole blood at 24, 48, 72 h, 1st and 2nd week. Significant increase in mean tail-length of DNA was observed at all time intervals after treatment with lead nitrate when compared to controls. The mean tail-length did not show a dose-related increase and the elevation in the mean tail-length was of a fluctuating type. Increase in mean tail-lengths clearly gives evidence that lead nitrate causes DNA damage effectively. The study indicates that the alkaline comet assay is a sensitive and rapid method to detect DNA damage caused by heavy metals.

Toxicity Study of Cerium Oxide Nanoparticles in Human Neuroblastoma Cells

The present study consisted of cytotoxic, genotoxic, and oxidative stress responses of human neuroblastoma cell line (IMR32) following exposure to different doses of cerium oxide nanoparticles (CeO2 NPs; nanoceria) and its microparticles (MPs) for 24 hours. Cytotoxicity was evaluated by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide and lactate dehydrogenase assays whereas genotoxicity was assessed using the cytokinesis-block micronucleus and comet assays. A battery of assays including lipid peroxidation, reactive oxygen species (ROS), hydrogen peroxide, reduced glutathione, nitric oxide, glutathione reductase, glutathione peroxidase, superoxide dismutase, catalase, and glutathione S-transferase were performed to test the hypothesis that ROS was responsible for the toxicity of nanoceria. The results showed that nanosized CeO2 was more toxic than cerium oxide MPs. Hence, further study on safety evaluation of CeO2 NPs on other models is recommended.

In vitro mutagenicity assessment of aluminium oxide nanomaterials using the Salmonella/microsome assay

The aim of the current study was to evaluate the potential mutagenicity of aluminium oxide nanomaterials (NMs) (Al(2)O(3)-30 nm and Al(2)O(3)-40 nm). Characterization of the NMs was done before the initiation of the study. The mutagenicity of the NMs was studied by the Ames test with Salmonella typhimurium TA100, TA1535, TA98, TA97a and TA102 strains, in the presence and absence of the S9 mixture. Based on a preliminary cytotoxicity study conducted on the strains, different concentrations of Al(2)O(3)-30 nm, Al(2)O(3)-40 nm and Al(2)O(3)-bulk were selected. At all the concentrations tested, Al(2)O(3)-30 nm and Al(2)O(3)-40 nm did not significantly increase the number of revertant colonies compared to the Al(2)O(3)-bulk and control with or without S9 mixture. Our findings suggest that Al(2)O(3) NMs were devoid of any size and concentration dependent mutagenicity compared to the Al(2)O(3)-bulk and control.