Comet Tail Length Research Articles

Single strand DNA breaks in rat brain cells exposed to microwave radiation

This investigation concerns with the effect of low intensity microwave (2.45 and 16.5 GHz, SAR 1.0 and 2.01 W/kg, respectively) radiation on developing rat brain. Wistar rats (35 days old, male, six rats in each group) were selected for this study. These animals were exposed for 35 days at the above mentioned frequencies separately in two different exposure systems. After the exposure period, the rats were sacrificed and the whole brain tissue was dissected and used for study of single strand DNA breaks by micro gel electrophoresis (comet assay). Single strand DNA breaks were measured as tail length of comet. Fifty cells from each slide and two slides per animal were observed. One-way ANOVA method was adopted for statistical analysis. This study shows that the chronic exposure to these radiations cause statistically significant ( p < 0.001) increase in DNA single strand breaks in brain cells of rat.

Protective effect of saffron (Crocus sativus L.) aqueous extract against genetic damage induced by anti-tumor agents in mice

The genotoxic potential of anti-tumor drugs limits their efficacy in the treatment of cancers. Since ancient times, saffron (dried stigmas of Crocus sativus L.) has been used as a spice and medicinal herb. Saffron is a rich source of carotenoids and is known for its anti-cancer and anti-tumor properties. The present study was designed to ascertain the chemoprotective potential of saffron against the genotoxicity of three well-known anti-tumor drugs-cisplatin (CIS), cyclophosphamide (CPH) and mitomycin-C (MMC)--using comet assay. Three doses of saffron (20, 40 and 80 mg/kg b.w.) were orally administered to mice for five consecutive days prior to the administration of anti-tumor drugs under investigation. Pre-treatment with saffron significantly inhibited anti-tumor drugs induced cellular DNA damage (strand breaks) as revealed by decreased comet tail length, tail moment and percent DNA in the tail. These findings, together with our previous results, suggest a potential role for saffron as an anti-genotoxic, anti-oxidant and chemopreventive agent and could be used as an adjuvant in chemotherapeutic applications.

Evaluation of genotoxicity in a group of workers from a petroleum refinery aromatics plant

Petroleum refinery workers are potentially exposed to a wide range of petroleum-derived hydrocarbons and chemical substances used in the manufacturing of petroleum derivatives. Benzene, toluene and xylene (BTX) are produced by distillation in the aromatics units and used as raw materials for petrol and petrochemical products. The aim of this study was to evaluate the genotoxic effects of occupational exposure to BTX in a petroleum refinery in the North of Portugal. The exposed group consisted of 48 workers from the aromatics plant and the control group consisted of 30 persons matched for various confounding factors. Chromosome aberrations (CA), micronuclei (MN), and DNA damage (evaluated by means of the comet assay) were measured in peripheral blood leukocytes. t, t-Muconic acid ( t, t-MA), hippuric acid (HA) and methylhippuric acid (MHA) concentrations were measured in urine samples collected at the end of the workshift. The results suggest that occupational exposure to toluene and xylene is very low. A statistically significant increase in t, t-MA excretion was found in the exposed group although t, t-MA levels were found to be lower than the biological exposure index (BEI). Significant increases were found for CA, MN and comet tail length (TL) in the exposed group ( p < 0.05). No association was found between tobacco smoking and the effect biomarkers analysed. A positive association was found between CA and MN with age in the control group ( p < 0.05).

Cytotoxicity and Genotoxicity Induced by the Pesticide Profenofos on Cultured Human Peripheral Blood Lymphocytes

Profenofos is a broad-spectrum organophosphate insecticide and acaricide used widely for agricultural and household purposes. The aim of this investigation was to determine its toxicity profile in vitro, using lymphocytes from peripheral blood samples of healthy human donors. We found the IC50 of profenofos to be 3.5 μM as measured by Trypan blue dye exclusion method. Chromosomal analyses of the metaphase plates of the samples treated with sublethal concentrations of profenofos revealed satellite associations and chromatid breaks and gaps, indicating its effect on chromosomes. The results were further supported by comet assay, where single-strand breaks in DNA were observed as comet tail lengths. The results were statistically significant (p < 0.01, ANOVA). Hence, it may be proposed that in vitro assays like the comet assay and chromosomal aberrations test, which indicate genetic damage, could be used to study the effect of organophosphorus pesticide poisoning in humans.

Lead-Induced Genotoxicity in Lymphocytes from Peripheral Blood Samples of Humans: In Vitro Studies

Lead is a known toxicant that has been implicated in encephalopathy in children and may affect the gastrointestinal and hematopoietic and other systems in adults. In fact, lead has been shown to compete with calcium for entry into the synaptosome and induce toxic effects. The aim of the current study was to evaluate the cytotoxic and genotoxic effects of lead by using lymphocytes from human peripheral blood in vitro. The LC50 for lead nitrate as determined by Trypan blue dye exclusion technique was found to be 3.14 mM. Chromosomal aberration frequency at sublethal doses (1/10 of LC50) as determined by examining the metaphase chromosomes (karyotyping) did not show significant aberrations except for some aneuploidy and about 2–4% gaps, breaks (3–4%), and about 5% satellite associations. However, significant DNA damage was determined by SCGE (Comet assay). The comet tail length proportionately increased with increasing lead nitrate concentration. Thus, Pb can induce single-strand DNA breaks, possibly by competing with metal binding sites.

Dose-dependent influence of genetic polymorphisms on DNA damage induced by styrene oxide, ethylene oxide and gamma-radiation

Styrene oxide (SO), ethylene oxide (EO) and gamma-radiation (G) are agents with a well-described metabolism and genotoxicity. EPHX1 and GSTs play an important role in the detoxification of electrophiles and oxidative stress. Enzymes involved in base excision repair (hOGG1, XRCC1), in rejoining single strand breaks (XRCC1) and in repair of cross-links and chromosomal double strand breaks (XRCC3) might have an impact on genotoxicity as well. In this study we assessed the dose-dependent effect of genetic polymorphisms in biotransforming ( EPHX (Tyr 113/His 113 and His 139/Arg 139), GSTP1 (Ile 105/Val 105), GSTM1 and GSTT1) and DNA repair enzymes ( hOGG1 (Ser 326/Cys 326), XRCC1 (Arg 194/Trp 194, Arg 280/His 280, Arg 399/Gln 399), XRCC3 (Thr 241/Met 241)) on the induced genotoxicity. Peripheral blood mononuclear cells from 20 individuals were exposed to 3 doses per agent (+control). Genotoxicity was evaluated by measuring comet tail length (TL) and micronucleus frequencies in binucleated cells (MNCB). Dose-dependent DNA damage was found for all agents and end-points, with the exception of MNCB induced by EO. Repeated measure ANOVA revealed a significant contribution of hOGG1 and XRCC3 genotypes to the inter-individual variability of TL and MNCB in cells exposed to EO and G. Homozygous hOGG1 326 wild cells showed significantly lower EO-induced TL than the heterozygous cells. Significantly higher TL and MNCB were found in EO-exposed cells carrying the XRCC3 241Met variant and the influence on TL was more pronounced at higher dose. In G-irradiated cells, TL was significantly higher in the hOGG1 326 homozygous wild types compared with mutated genotypes. The influence of hOGG1 326 on TL was borderline dose-dependent. We conclude that the influence of genetic polymorphisms of enzymes involved in DNA repair on induced genotoxicity depends on exposure dose.

Effects of extremely low frequency electromagnetic fields on DNA of testicular cells and sperm chromatin structure in mice

To study the effects of 50 Hz electromagnetic fields (EMFs) on DNA of testicular cells and sperm chromatin structure in mice. Mice were exposed to 50 Hz, 0.2 mT or 6.4 mT electromagnetic fields for 4 weeks. DNA strand breakage in testicular cells was detected by single-cell gel electrophoresis assay. Sperm chromatin structure was analyzed by sperm chromatin structure assay with flow cytometry. After 50 Hz, 0.2 mT or 6.4 mT EMFs exposure, the percentage of cells with DNA migration in total testicular cells increased from the control level of 25.64% to 37.83% and 39.38% respectively. The relative length of comet tail and the percentage of DNA in comet tail respectively increased from the control levels of 13.06% +/- 12.38% and 1.52% +/- 3.25% to 17.86% +/- 14.60% and 2.32% +/- 4.26% after 0.2 mT exposure and to 17.88% +/- 13.71% and 2.35% +/- 3.87% after 6.4 mT exposure (P < 0.05). Exposure to EMFs had not induced significant changes in S.D.alphaT and XalphaT, but COMPalphaT (cells outside the main population of alpha t), the percentage of sperms with abnormal chromatin structure, increased in the two exposed groups. 50 Hz EMFs may have the potential to induce DNA strand breakage in testicular cells and sperm chromatin condensation in mice.

Variability in fecal water genotoxicity, determined using the Comet assay, is independent of endogenous N‐Nitroso compound formation attributed to red meat consumption

Red meat consumption causes a dose-dependent increase in fecal apparent total N-nitroso compounds (ATNC). The genotoxic effects of these ATNCs were investigated using two different Comet assay protocols to determine the genotoxicity of fecal water samples. Fecal water samples were obtained from two studies of a total of 21 individuals fed diets containing different amounts of red meat, protein, heme, and iron. The first protocol incubated the samples with HT-29 cells for 5 min at 4 degrees C, whereas the second protocol used a longer exposure time of 30 min and a higher incubation temperature of 37 degrees C. DNA strand breaks were quantified by the tail moment (DNA in the comet tail multiplied by the comet tail length). The results of the two Comet assay protocols were significantly correlated (r = 0.35, P = 0.003), however, only the second protocol resulted in detectable levels of DNA damage. Inter-individual effects were variable and there was no effect on fecal water genotoxicity by diet (P > 0.20), mean transit time (P = 0.588), or weight (P = 0.705). However, there was a highly significant effect of age (P = 0.019). There was no significant correlation between concentrations of ATNCs in fecal homogenates and fecal water genotoxicity (r = 0.04, P = 0.74). ATNC levels were lower in fecal water samples (272 microg/kg) compared to that of fecal homogenate samples (895 microg/kg) (P < 0.0001). Failure to find dietary effects on fecal water genotoxicity may therefore be attributed to individual variability and low levels of ATNCs in fecal water samples.

Influence of a low-molecular-weight heparin derivative on the nitric oxide levels and apoptotic DNA damage in adriamycin-induced cardiac and renal toxicity

The spectrum of the anti-apoptotic potential of heparin is currently under scrutiny in various tissues and under various pathological situations. In this study, the role of a low-molecular-weight heparin derivative (LMWH), certoparin in adriamycin-induced oxidative DNA damage has been evaluated in the cardiac and renal tissues. Two groups of male albino rats of the Wistar strain (140 ± 10 g) received a single intravenous injection of adriamycin (7.5 mg/kg), and one of them received low-molecular-weight heparin (Certoparin Sodium, 300 μg/day/rat s.c.) treatment, commencing on day 8, continued for a week. The nitrosative stress in ADR cytotoxicity is indicated by the 1.51-fold cardiac and 2.36-fold renal increase in reactive nitrogen species (RNS), while LMWH treatment restores normalcy ( p < 0.001). The influence of LMWH on the pro-inflammatory and pro-apoptotic cytokine, TNF-α was studied. Renal and cardiac levels of TNF-α showed a significant rise ( p < 0.001) in the ADR cytotoxic group, while the TNF-α values departed towards control levels in the LMWH treated group ( p < 0.001). DNA damage indicated by the fragmentation pattern (agarose gel electrophoresis) and the significantly increased comet tail length ( p < 0.001) observed after alkaline single cell gel electrophoresis confirmed the toxicity induced by ADR on DNA in the untreated group. In the LMWH-treated group, the observation of intact DNA band after agarose gel electrophoresis, and the finding of comet tail length being comparable with that of the control substantiated the protection rendered by the LMWH, certoparin. In short, the results suggest that the low-molecular-weight heparin derivative, certoparin exerts beneficial effects on the nitrosative status, and on the biological macromolecules as DNA and curtails the rise of the pro-apoptotic and pro-inflammatory cytokine, TNF-α in the cardiac and renal tissues.

Evaluation of oxidative stress and genotoxicity in organophosphorus insecticide formulators

The aim of this study was to evaluate genotoxicity and oxidative stress in workers who formulate organophosphorus (OP) pesticides. In this survey, blood leukocytes and erythrocytes of a group of 21 pesticide formulating workers and an equal number of control subjects were examined for genotoxicity and oxidative stress parameters. The mean comet tail length and mean comet length were used to measure DNA damage. Lipid peroxidation level, catalase, superoxide dismutase (SOD) and glutathione peroxidase activities in erythrocytes were analysed as biomarkers of oxidative stress. In addition, the acetylcholinesterase activity was measured as a biomarker of toxicity. The average duration of employment of workers in the factory was 97 months. Results indicated that chronic exposure (multiple-dose, greater than or equal to 6 months duration) to OP pesticides was associated with increased activities of catalase, SOD and glutathione peroxidase in erythrocytes. The level of lipid peroxidation and acetylcholinesterase activity did not show any significant differences between the two groups. The results also indicated that chronic exposure to OP pesticides was associated with increased DNA damage. It is concluded that human chronic exposure to OP pesticides may result in stimulated antioxidant enzymes and increased DNA damage in the absence of depressed acetylcholinesterase levels. Routine genotoxicity monitoring concomitant to acetylcholinesterase activity in workers occupationally exposed to OP insecticides is suggested.

Monitoring of the impact of Prestige oil spill on Mytilus galloprovincialis from Galician coast

In November 2002, the Prestige oil tanker was wrecked in front of Galician coast (NW of Spain), spilling near 63,000 tons of heavy oil until February 2003. Contamination produced was very extensive (70% of Galician beaches were reached by the oil) but heterogeneous, alternating intensely affected zones with neighbour locations where the repercussion was minimal. The objective of this study was to monitor sea environment contamination caused by Prestige oil spill during an 11-month period (August 2003–June 2004, nine samplings) in two locations of Galician coast with different geographical properties (Lira and Ancoradoiro beaches), by means of chemical determination of total polycyclic aromatic hydrocarbons (TPAH) in seawater, and using as exposure biomarker TPAH content in mussel ( Mytilus galloprovincialis) tissues, and as effect biomarker DNA damage in mussel gills, evaluated by the comet assay. In addition, recovery ability of the mussels was determined after a 7-day stay in the laboratory. TPAH contents in seawater were very high in the earliest samplings, but then they maintained below 200 ng L − 1, similar to reference seawater. However, TPAH levels in mussel tissues were more variable: they increased again from January 2004, probably due to the adverse meteorological conditions that turned over the sea bottom and dispersed the oil accumulated in sediments. In most samplings, these levels decreased during the recovery stage. DNA damage in oil-exposed mussels was significantly higher than in reference mussels, both before and after the recovery phase, but they did not differ to one another. Comet tail length was slightly reduced during the recovery stage, indicative of a certain DNA repair in exposed mussels. This study showed up the importance of monitoring sea contamination events during an extended time, not only in evaluating the presence of the contaminants in the environment but also in determining their bioaccumulation and their effect on the exposed organisms.

DNA damage among thyroid cancer and multiple cancer cases, controls, and long-lived individuals

Variation in the detection, signaling, and repair of DNA damage contributes to human cancer risk. To assess capacity to modulate endogenous DNA damage among radiologic technologists who had been diagnosed with breast cancer and another malignancy (breast-other, n = 42), early-onset breast cancer (early-onset, age ≤35; n = 38), thyroid cancer ( n = 68), long-lived cancer-free individuals (hyper-normals, n = 20) and cancer-free controls ( n = 49) we quantified DNA damage (single strand breaks and abasic sites) in untreated lymphoblastoid cell lines using the alkaline comet assay. Komet™ software provided comet tail length, % DNA in tail (tail DNA), comet distributed moment (CDM), and Olive tail moment (OTM) summarized as the geometric mean of 100 cells. Category cut-points (median and 75th percentile) were determined from the distribution among controls. Tail length (for ≥75% versus below the median, age-adjusted) was most consistently associated with the highest odds ratios in the breast-other, early-onset, and thyroid cancer groups (with risk increased 10-, 5- or 19-fold, respectively, with wide confidence intervals) and decreased risk among the hyper-normal group. For the other three comet measures, risk of breast-other was elevated approximately three-fold. Risk of early-onset breast cancer was mixed and risk of thyroid cancer ranged from null to a two-fold increase. The hyper-normal group showed decreased odds ratios for tail DNA and OTM, but not CDM. DNA damage, as estimated by all comet measures, was relatively unaffected by survival time, reproductive factors, and prior radiation treatment. We detected a continuum of endogenous DNA damage that was highest among cancer cases, less in controls, and suggestively lowest in hyper-normal individuals. Measuring this DNA damage phenotype may contribute to the identification of susceptible sub-groups. Our observations require replication in a prospective study with a large number of pre-diagnostic samples.

DNA damage in lymphocytes of Indian rickshaw pullers as measured by the alkaline comet assay

Rickshaw pullers (RPs) engage in strenuous physical activity and are exposed to the air pollutants found in urban environments. Air pollutants and the reactive oxygen species generated by the physical activity both potentially can damage DNA. In the present study, the Comet assay, a sensitive tool for measuring DNA damage in single cells, was used to study genomic DNA damage in lymphocytes of Indian RPs. The study evaluated DNA damage in 118 healthy male volunteers, including 63 RPs whose work demanded high levels of physical activity for 7-9 hr/day, and 55 controls matched for age, habits, socio-economic status, and exposure to air pollution. A significant increase was found for the mean Olive tail moment (arbitrary units) among the RPs (4.13 +/- 0.11; P < 0.001) in comparison with the controls (3.21 +/- 0.10). Likewise, comet tail length (microm) (RPs: 58.98 +/- 1.01 vs. controls: 52.38 +/- 1.24) and tail DNA (%) (RPs: 13.52 +/- 0.31 vs. controls: 10.04 +/- 0.24) were also significantly higher for RPs compared with those of their matched controls (both, P < 0.001). To our knowledge, this is the first demonstration that physical activity due to occupation can produce DNA damage in peripheral lymphocytes.

A biomarker model of sublethal genotoxicity (DNA single-strand breaks and adducts) using the sentinel organism Aporrectodea longa in spiked soil

There is a need to develop risk biomarkers during the remediation of contaminated land. We employed the earthworm, Aporrectodea longa (Ude), to determine whether genotoxicity measures could be applied to this organism's intestinal tissues. Earthworms were added, for 24 h or 7 days, to soil samples spiked with benzo[ a]pyrene (B[ a]P) and/or lindane. After exposure, intestinal tissues (crop/gizzard or intestine) were removed prior to the measurement in disaggregated cells of DNA single-strand breaks (SSBs) by the alkaline comet assay. Damage was quantified by comet tail length (CTL, μm). B[ a]P 24-h exposure induced dose-related increases ( P<0.0001) in SSBs. Earthworm intestine was significantly ( P<0.0001) more susceptible than crop/gizzard to B[ a]P and/or lindane. However, both tissues appeared to acquire resistance following 7-day exposure. B[ a]P-DNA adducts, measured by 32P-postlabelling, showed a two-adduct-spot pattern. This preliminary investigation suggests that earthworm tissues may be incorporated into genotoxicity assays to facilitate hazard identification within terrestrial ecosystems.

Cylindrospermopsin Genotoxicity and Cytotoxicity: Role Of Cytochrome P-450 and Oxidative Stress

Cylindrospermopsin (CYN) is a cyanobacterial toxin found in drinking-water sources world wide. It was the likely cause of human poisonings in Australia and possibly Brazil. Although CYN itself is a potent protein synthesis inhibitor, its acute toxicity appears to be mediated by cytochrome p-450 (CYP450)-generated metabolites. CYN also induces genotoxic effects both in vitro and in vivo, and preliminary evidence suggests that tumors are generated by oral exposure to CYN. To understand the role of CYP450-activated CYN metabolites on in vitro genotoxicity, this study quantified the process in primary mouse hepatocytes using the COMET assay in both the presence and absence of CYP450 inhibitors known to block acute CYN cytotoxicity. CYN was cytotoxic at concentrations above 0.1 μM(EC50 = 0.5 μM) but produced significant increases in Comet tail length, area, and tail moment at 0.05 μM and above; hence genotoxicity is unlikely to be secondary to metabolic disruption due to toxicity. The CYP450 inhibitors omeprazole (100 μM) and SKF525A (50 μM) completely inhibited the genotoxicity induced by CYN. The toxin also inhibits production of glutathione (GSH), a finding confirmed in this study. This could potentiate cytotoxicity, and by implication genotoxicity, via reduced reactive oxygen species (ROS) quenching. The lipid peroxidation marker, malondialdehyde (MDA) was quantified in CYN-treated cells, and the effect of the reduced glutathione (GSSG) reductase (GSSG-rd.) inhibitor 1,3-bis(chloroethyl)-l-nitrosourea (BCNU) on both MDA production and lactate dehydrogenase (LDH) leakage was examined. MDA levels were not elevated by CYN treatment, and block of GSH regeneration by BCNU did not affect lipid peroxidation or cytotoxicity. It therefore seems likely that CYP450-derived metabolites are responsible for both the acute cytotoxicity and genotoxicity induced by CYN. This work was funded by the Cooperative Research Centre for Water Quality and Treatment. The authors thank Yvette de Graaf for help with the COMET assay, and Dr. Tanya Lewanowitsch for useful and timely advice.

Use of Comet and Micronucleus Assays to Measure Genotoxicity in Meadow Voles (Microtus pennsylvanicus) Living in Golf Course Ecosystems Exposed to Pesticides

The purpose of this study was to conduct a biomonitoring study to measure the effects of pesticide exposure in meadow voles (Microtus pennsylvanicus) living in golf courses of the Ottawa/Gatineau region of Canada. In this article we present the results from the comet and micronucleus assay. Voles were captured in 2001 and 2002 at five golf courses and two reference sites. Blood was collected from sedated voles. Three animals from each course were euthanized to determine body burdens of historically used organochlorine (OC) and metal-based pesticides. Exposure to in-use pesticides was determined from detailed golf course pesticide use records. Comet tail length and tail moment were not related to body burdens of OC pesticides and metals historically used on these golf courses. In generally, tail length and moment significantly decreased in relation to days since last application of a pesticide, and to days since the last application of a specific fungicide (Daconil) containing a potentially genotoxic active ingredient (chlorothalonil). The slopes of these curves in 2002 were not significantly different than the half-life decay curve of chlorothalonil on vegetation. Both comet assay parameters appeared to increase in a dose-dependent manner with the amount of the last application Daconil. The number of micronucleated polychromatic erythrocytes was not related to any pesticide application parameter.

Assessment of the in vivo genotoxicity of vanadate: Analysis of micronuclei and DNA damage induced in mice by oral exposure

Vanadium compounds are able to interact with living cells exerting a variety of biological effects. The pentavalent form is the most stable and toxic form of the element. In systems in vitro pentavalent vanadium is an effective genotoxic agent, inducing DNA damage and chromosome malsegregation at low doses. On the other hand, no adequate in vivo data are available for the characterization of the genotoxic hazard following oral intake, the most relevant route of human exposure. In this study, the genotoxic effects produced by the oral intake of sodium ortho-vanadate (Na 3VO 4) were investigated. Male CD-1 mice were treated for 5 weeks with a range of concentrations of Na 3VO 4 in drinking water (0.75–1500 mg/l). Both micronuclei and primary DNA lesions as detected by comet assay were assessed in several tissues. Statistically significant increases of micronuclei in bone marrow were observed in mice receiving the two highest concentrations of Na 3VO 4 (750 and 1500 mg/l). A significant increase of comet tail length was observed in splenocytes of mice receiving Na 3VO 4 at 1500 mg/l, whereas no effect was observed in bone marrow and testis cells. No treatment-related effect on sperm chromatin structure or on testis cell population was observed. The determination of vanadium content in mouse tissues at the end of treatment highlighted a very low internal exposure, especially in soft tissues. Overall, the results obtained indicate that the genotoxic activity of pentavalent vanadium is expressed in vivo only following high dose exposure, possibly as a consequence of the poor bioavailability of the element.

Detection of DNA damage by alkaline single cell gel electrophoresis in 2,4-dichlorophenoxyacetic-acid- and butachlor-exposed erythrocytes of Clarias batrachus

The alkaline single cell gel electrophoresis, also known as comet assay, is a rapid, simple and sensitive technique for measuring DNA strand breaks in individual cells. The present study was undertaken to evaluate the genotoxic potential of two widely used herbicides; 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-chloro-2,6-diethyl- N-(butoxymethyl) acetanilide (butachlor) in erythrocytes of freshwater catfish, Clarias batrachus. Fish were exposed by medium treatment with three sub-lethal concentrations of 2,4-D (25, 50, and 75 ppm) and butachlor (1, 2, and 2.5 ppm) and alkaline comet assay was performed on nucleated erythrocytes after 48, 72, and 96 h. The amount of DNA damage in cells was estimated from comet tail length as the extent of migration of the genetic material. A significant increase in comet tail length indicating DNA damage was observed at all concentrations of both the herbicides compared with control ( P<0.05). The mean comet tail length showed a concentration-related and time-dependent increase as the maximum tail length recorded at highest concentration and longer duration of 2,4-D (9.59 μm) and butachlor (9.28 μm). This study confirmed that the comet assay applied on the fish erythrocyte is a useful tool in determining potential genotoxicity of water pollutants and might be appropriate as a part of a monitoring program.

DNA damage in lymphocytes of rural Indian women exposed to biomass fuel smoke as assessed by the Comet assay

The Comet assay has found wide acceptance in monitoring human genotoxicity caused by lifestyle and occupational and environmental factors. In the present study, we have used the Comet assay to measure the DNA damage in a population of rural Indian women cooking with biomass fuels (BMFs; fire wood and cow dung cakes). Out of 144 volunteers, 70 used BMFs for domestic cooking, while the remaining 74 used liquefied petroleum gas (LPG) and served as a reference population. All the individuals had comparable socioeconomic backgrounds and were between 20 and 55 years of age. Significantly higher levels of DNA damage were observed for BMF users than for LPG users. For BMF users in comparison with the reference population, Olive tail moment was 3.83 +/- 0.15 (arbitrary units) vs. 2.77 +/- 0.07 (P < 0.001); % tail DNA was 11.19 +/- 0.35 vs. 8.29 +/- 0.20 (P < 0.001); and comet tail length (microm) was 51.15 +/- 1.37 vs. 40.26 +/- 0.88 (P < 0.001). Similar significant differences were found when the groups were stratified by age and length of exposure. This study suggests that exposure to BMF smoke leads to greater levels of DNA damage than exposure to LPG combustion products.

Genetic damage in mobile phone users: some preliminary findings

BACKGROUND: The impact of microwave (MW)/radio frequency radiation (RFR) on important biological parameters is probably more than a simply thermal one. Exposure to radio frequency (RF) signals generated by the use of cellular telephones have increased dramatically and reported to affect physiological, neurological, cognitive and behavioural changes and to induce, initiate and promote carcinogenesis. Genotoxicity of RFR has also been reported in various test systems after in vitro and/or in vivo exposure but none in mobile phone users. AIMS: In the present study, DNA and chromosomal damage investigations were carried out on the peripheral blood lymphocytes of individuals using mobile phones, being exposed to MW frequency ranging from 800 to 2000 MHz. METHODS: DNA damage was assessed using the single cell gel electrophoresis assay and aneugenic and clastogenic damage by the in vivo capillary blood micronucleus test (MNT) in a total of 24 mobile phone users. RESULTS: Mean comet tail length (26.76 ± 0.054 mm; 39.75% of cells damaged) in mobile phone users was highly significant from that in the control group. The in vivo capillary blood MNT also revealed highly significant (0.25) frequency of micronucleated (MNd) cells. CONCLUSIONS: These results highlight a correlation between mobile phone use (exposure to RFR) and genetic damage and require interim public health actions in the wake of widespread use of mobile telephony.