Radiofrequency electromagnetic fields (UMTS, 1,950 MHz) induce genotoxic effects in vitro in human fibroblasts but not in lymphocytes

Objective Universal Mobile Telecommunication System (UMTS) was recently introduced as the third generation mobile communication standard in Europe. This was done without any information on biological effects and genotoxic properties of these particular high-frequency electromagnetic fields. This is discomforting, because genotoxic effects of the second generation standard Global System for Mobile Communication have been reported after exposure of human cells in vitro. Methods Human cultured fibroblasts of three different donors and three different short-term human lymphocyte cultures were exposed to 1,950 MHz UMTS below the specific absorption rate (SAR) safety limit of 2 W/kg. The alkaline comet assay and the micronucleus assay were used to ascertain dose and time-dependent genotoxic effects. Five hundred cells per slide were visually evaluated in the comet assay and comet tail factor (CTF) was calculated. In the micronucleus assay 1,000 binucleated cells were evaluated per assay. The origin of the micronuclei was determined by fluorescence labeled anticentromere antibodies. All evaluations were performed under blinded conditions. Results UMTS exposure increased the CTF and induced centromere-negative micronuclei (MN) in human cultured fibroblasts in a dose and time-dependent way. Incubation for 24 h at a SAR of 0.05 W/kg generated a statistically significant rise in both CTF and MN (P = 0.02). At a SAR of 0.1 W/kg the CTF was significantly increased after 8 h of incubation (P = 0.02), the number of MN after 12 h (P = 0.02). No UMTS effect was obtained with lymphocytes, either unstimulated or stimulated with Phytohemagglutinin. Conclusion UMTS exposure may cause genetic alterations in some but not in all human cells in vitro.     

槲皮素在体外哺乳动物细胞中遗传毒性研究

目的研究槲皮素对体外哺乳动物的细胞遗传毒性。方法采用80、40、20、10、5 mg/L5个剂量组的槲皮素在有或无代谢活化条件下处理体外培养的中国地鼠肺成纤维细胞（CHL）3 h后更换新鲜培养液,恢复生长21 h后收获细胞制片,观察槲皮素对哺乳动物细胞染色体的影响。采用200、100、50、25和12.5 mg/L 5个剂量组的槲皮素在有或无代谢活化条件下处理中国仓鼠肺成纤维细胞（V79）3 h后,经过7 d的次黄嘌呤鸟嘌呤磷酸核糖转移酶（HGPRT）突变基因表达和7 d突变基因选择后计数集落形成率并计突变频率,观察槲皮素对哺乳动物HGPRT基因位点的影响。结果在有或无代谢活化条件下槲皮素在浓度〉10 mg/L均能够诱导CHL细胞染色体断裂和交换等,染色体细胞畸变率显著增加（P〈0.01）;而在有或无代谢活化与溶剂对照组相比较槲皮素各剂量组均未发生基因突变频率显著增加（P〉0.05）。结论在体外试验条件下,槲皮素对哺乳动物细胞显示出明显致突变性,存在潜在的遗传毒性。     

Micronuclei Assay in Exfoliated Buccal Cells from Individuals Exposed to Arsenic in Argentina

Drinking arsenic (As)-laden water for a long time affects a population’s health and leads to chronic hydroarsenicism, which is associated with an increased incidence of different types of cancer. To determine the potential genotoxic risk associated with different degrees of environmental exposure to inorganic As by way of drinking water, micronuclei (MN) frequency in exfoliated buccal cells was evaluated in Argentina among rural populations of Santiago del Estero and urban populations of Buenos Aires. The exposed group in Santiago del Estero (La Firmeza and Santos Lugares localities) showed a significant increase in MN frequency in epithelial cells compared with controls (Monte Quemado and Urutau localities) (p = 0.0005). With regard to the Buenos Aires groups, Navarro individuals (the exposed group) exhibited a significant difference compared with controls (Ciudad Autónoma de Buenos Aires) (p = 0.0002). Comparison of MN frequencies between Santiago del Estero and Buenos Aires individuals showed that genotoxic effects of As in drinking water exhibit variation between rural and urban groups, probably due to individual susceptibility being an important incidence factor. The results clearly show that MN assay in buccal mucosa cells is an ideal methodology with which to measure potential genetic risk related to environmental As exposure in humans.     

农药鱼藤酮的遗传毒性鉴定

目的检测农药鱼藤酮的遗传毒性。方法用Ames实验检测回复突变作用，以CHL细胞实验和微核实验检测染色体畸变效应。结果阳性对照剂能诱导显著的突变效应，鱼藤酮在所选用剂量范围内不能诱导显著的突变效应。结论本实验室条件下鱼藤酮不显示明确的致突变作用。     

昆明山海棠雄性抗生育活性提取物TH5的毒性评价

目的:对昆明山海棠雄性抗生育活性提取物TH5的毒性试验结果进行评价。方法:TH5的毒性试验用急性毒性试验(LD50)、Ames试验、CHL细胞染色体畸变试验及微核试验方法进行检测。结果:TH5之ID_(50)为3.27g/kg;Ames试验在0.5～5000μg/皿5个剂量范围内加与不加S9条件下,4个菌株的回变菌落数均未有2倍增加;TH5之CHL细胞染色体畸变试验在其最终浓度为1/4IC50、1/2IC50及IC50(11～44μg/ml)时无论加S9与否,细胞畸变率与溶剂对照组无显著差异(P>0.05);TH5在30～300mg/kg3个剂量水平其微核率与溶剂对照组也均无显著差异(P>0.05)。结论;TH5的抗生育有效剂量(116mg/kg)范围内3种诱变试验结果均为阴性,仍不失其开发价值。     

Structurally related mycotoxins ochratoxin A, ochratoxin B, and citrinin differ in their genotoxic activities and in their mode of action in human-derived liver (HepG2) cells: implications for risk assessment

To elucidate the effects of three structurally related mycotoxins, namely, ochratoxin A (OTA), ochratoxin B (OTB), and citrinin (CIT), on human health, we investigated their acute toxic, mitogenic, and genotoxic effects in the human-derived liver cell line (HepG2). These compounds are found in moldy foods in endemic areas of nephropathy, which is associated with urinary tract cancers. In agreement with previous experiments, we found that OTA causes a dose-dependent induction of micronuclei (MN) and DNA migration in the single-cell gel electrophoresis (SCGE) assay, which was statistically significant at concentrations of > or =5 microg/ml. In contrast, OTB was devoid of genotoxic activity under identical conditions, but the compound caused pronounced inhibition of cell division even at doses lower than OTA (10 microg/ml). CIT caused an effect similar to that of OTA in MN assays (significant at dose levels of > or =2.5 microg/ml) but was negative in the SCGE test. All compounds failed to induce mutations in Salmonella/microsome assays in strains TA 98 and TA 100 after addition of HepG2-derived enzyme homogenate (S9-mix). By use of DNA-centromeric probes we found that induction of MN by OTA involves chromosome breaking effects (55-60% of the MN were centromere negative), whereas CIT-induced MN were predominantly centromere positive (78-82%). Our findings indicate that OTB is devoid of genotoxic activity in human-derived cells and therefore probably not a genotoxic carcinogen in humans. In contrast, CIT was an equally potent inducer of MN in HepG2 cells as OTA, but this effect is caused by a different mechanism, namely, aneuploidy. Furthermore, our data suggest that combined exposure to structurally related mycotoxins that cause DNA damage via completely different mechanisms may significantly increase the cancer risk of humans consuming moldy foods.     

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

Electric arc welding is known to involve considerable exposure to extremely low-frequency magnetic fields (ELF-MF). A cytogenetic monitoring study was carried out in a group of welders to investigate the genotoxic risk of occupational exposure to ELF-MF. This study assessed individual occupational exposure to ELF-MF using a personal magnetic-field dosimeter, and the cytogenetic effects were examined by comparing micronuclei (MN) and sister chromatid exchange (SCE) frequencies in the lymphocytes of the exposed workers with those of non-exposed control subjects (blood donors) matched for age and smoking habit. Cytogenetic analyses were carried out on 21 workers enrolled from two different welding companies in Central Italy and compared to 21 controls. Some differences between the groups were observed on analysis of SCE and MN, whereas replication indices in the exposed were found not to differ from the controls. In particular, the exposed group showed a significantly higher frequency of MN (group mean ± SEM: 6.10 ± 0.39) compared to the control group (4.45 ± 0.30). Moreover, the increase in MN is associated with a proportional increase in ELF-MF exposure levels with a dose-response relationship. A significant decrease in SCE frequency was observed in exposed subjects (3.73 ± 0.21) compared to controls (4.89 ± 0.12). The hypothesis of a correlation between genotoxic assays and ELF-MF exposure value was partially supported, especially as regards MN assay. Since these results are derived from a small-scale pilot study, a larger scale study should be undertaken.     

Genotoxic Effects and LC<Subscript>50</Subscript> Value of NaOCl on <Emphasis Type="Italic">Orthrias angorae</Emphasis> (Steindachner 1897)

Studies show that different organisms used as bio-indicators have indicated several genotoxic and mutagenic effects of disinfected waters. In this study, the 96 h LC(50 )mean value of NaOCl for Orthrias angorae was calculated to be 0.5509 mg/L. The results showed that NaOCl is highly toxic to O. angorae specimens. Statistical analysis demonstrated a significant increase in micronuclei after the induction of 0.5 mg/L NaOCl concentration after 36 h. The same increase has been reported for 0.37 and 0.5 mg/L NaOCl concentrations after 72 h. Even though the MN frequency of 0.37 mg/L was similar after 36 and 72 h, only 72 h micronuclei frequency was statistically significant. The 72 h MN frequency of the negative control group was smaller than 36 h MN frequency of the negative control group. This discrepancy has led to 72 h MN frequency being statistically significant. MN frequency of 0.25 mg/L NaOCl concentration was insignificant when compared to negative test groups. The benzene treatment also caused a significant increase (p < 0.01) in the frequency of micronucleated erythrocytes.     

The effects of thymol on sister chromatid exchange,chromosome aberration and micronucleus in human lymphocytes

The genotoxic effects of thymol were investigated in human peripheral lymphocytes treated with 25, 50, 75, and 100 μg/ml concentrations of thymol for 24 and 48 h treatment periods by using sister chromatid exchange (SCE), chromosome aberration (CA), and micronucleus (MN) tests. Nuclear division index (NDI), replication index (RI), and mitotic index (MI) were also calculated in order to determine the cytotoxicity of thymol. Thymol significantly increased the SCE, especially at the lower concentrations. Thymol also increased the SCE at the highest concentrations without statistical significance. Thymol induced both the structural CA and frequency of MN at all concentrations. Thymol dose-dependently decreased the NDI for two treatment periods. Thymol decreased the RI for the 24 h treatment time without any statistical significance. However, thymol decreased the RI for the 48 h treatment time in a dose-dependent manner. Thymol also decreased the MI at the higher concentration without dose-dependent effect.     

Negative results of<Emphasis Type="Italic">umu</Emphasis> genotoxicity test of fluorotelomer alcohols and perfluorinated alkyl acids

Objectives  Recently, perfluorooctanoate (PFOA) has been ubiquitously detected in the environment as well as in human serum. Fluorotelomer alcohols (FTOHs), a precursor of PFOA, undergo biodegradation via several metabolic routes which leads to formation of various biodegradation products. The degradation of FTOHs produces an α,β-unsaturated aldehyde that seems possibly to be electrophilic and may react with cellular macromolecules including DNA. Methods  We investigated the genotoxicity of three FTOHs (6∶2 FTOH, 8∶2 FTOH and 10∶2 FTOH), PFOA and perfluorooctane sulfonate (PFOS) using theumu test. Results  The FTOHs, PFOA and PFOS showed no significant increases in β-galactosidase activity at 0–1000 μM in the absence of S9 mix. The results were unchanged by the metabolic activation with S9 mix. Conclusion  The genotoxicities of FTOHs, PFOA or PFOS are not detectable using the present method, suggesting that they are unlikely mutagens.     

Exposure to organic solvents and cytogenetic damage in exfoliated cells of the buccal mucosa from shoe workers

Purpose  We determined the solvents mainly used in shoe making and their genotoxic effects. Methods  Thirty-four exposed shoe workers and 34 unexposed control subjects, paired by age and sex, were compared. Occupational exposure was determined by using monitors 3M. Solvents were assessed by gas chromatography. Exfoliated buccal cells were obtained from each subject to determine the incidence of micronuclei and other nuclear abnormalities. One thousand cells were counted in each subject. Results  Solvents detected were acetone, ethyl acetate, methyl ethyl ketone, and toluene. The incidence of nuclear abnormalities was significatively higher in the exposed group when compared to the control group. A positive relationship between the incidence of micronuclei and the toluene concentration in the environment was found. Conclusions  Toluene shows an important genotoxic effect. As the micronuclei test is an effective, fast, simple and low cost biomarker to identify cytogenetic effects, we suggest its utilization as a preventive test of genotoxicity.     

Micronucleus test using cultured new born rat astrocytes

Micronuclei is induced in cytoplasm as a consequence of the formation of chromosomal fragments or remaining chromosomes during cell division by the cause of clastogens or spindle poisons, and is used as an indicator of genotoxicity screening tests. There are few short-term genotoxicity screening tests using brain cells. We attempted to establish a new in vitro micronucleus test (MN test) system by use of central nervous system cells. Primary cultured astrocytes were prepared from newborn male Sprague-Dawley (SD) rats. In growth curve of astrocytes, doubling time was determined to be 31 h. In time study, the highest frequency of micronuclei was observed at 48 h, 72 h and 6 h-exposure-66 h-recovery by vincristine (VCR), mitomycin C (MMC) without metabolic activation system and cyclophosphamide (CPM) with metabolic activation system, respectively. Dose-response relationships between micronucleus frequency and concentrations of MMC, VCR and CPM were observed, respectively. It is suggested that the in vitro MN test using new born rat-astrocytes could be used as a screening test of environmental and occupational genotoxic chemicals in the central nervous system cells.     

Differential induction of micronuclei in peripheral lymphocytes and exfoliated urothelial cells of workers exposed to 4,4'-methylenebis-(2-chloroaniline) (MOCA) and bitumen fumes

Cytogenetic end-points used to estimate risk of genotoxic events in workers include the measurement of micronuclei (MN) in exfoliated cells, lymphocytes, and other tissues. Micronuclei are chromatin-containing bodies outside the cell nucleus resulting from contaminant-induced DNA damage. A review of 71 reports of human genotoxic responses to chemical or physical agents published between 1999 and 2001 revealed that 14% of such studies measured genotoxicity endpoints in specific target tissues relevant to the site of disease for the agent examined; 18% used endpoints in surrogate or non-target tissues but considered the relations between endpoints in surrogate and disease target tissues, and 68% measured genotoxicity endpoints in accessible tissues without reference to specific targets for disease. Methylenebis-(2-chloroaniline) (MOCA), used in polyurethane manufacture, is a suspected bladder carcinogen. Bitumen, used in road surfacing, contains skin and lung carcinogens. In this study, we aimed to compare genotoxicity in urothelial cells and in lymphocytes of workers exposed to these materials. Twelve men employed in polyurethane manufacture, twelve bitumen road layers, and eighteen hospital stores personnel (controls) were recruited and all provided blood and urine samples on the same day. Blood cultures were prepared using a cytochalasin B-block method. Exfoliated urothelial cells were collected from urine and stained for light microscopy. The number of MN in urothelial cells was higher in MOCA-exposed (14.27 +/- 0.56 MN/1000, 9.69 +/- 0.32 MN cells/1000) than in bitumen exposed workers (11.99 +/- 0.65 MN/1000, 8.66 +/- 0.46 MN cells/1000) or in control subjects (6.88 +/- 0.18 MN/1000, 5.17 +/- 0.11 MN cells/1000). Conversely, in lymphocytes, MN were higher in bitumen-exposed (16.24 +/- 0.63 MN/1000, 10.65 +/- 0.24 MN cells/1000) than in MOCA-exposed workers (13.25 +/- 0.48 MN/1000, 8.54 +/- 0.14 MN cells/1000) or in control subjects (9.24 +/- 0.29 MN/ 1000, 5.93 +/- 0.13 MN cells/1000). The results of this study suggest that genotoxins can cause different rates of micronuclei formation in different tissues. Thus, the sensitivity and relevance to cancer risk may be greater if the tissues selected for genotoxicity studies reflect the target tissue for the chemicals concerned.     

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

Electric arc welding is known to involve considerable exposure to extremely low-frequency magnetic fields (ELF-MF). A cytogenetic monitoring study was carried out in a group of welders to investigate the genotoxic risk of occupational exposure to ELF-MF. This study assessed individual occupational exposure to ELF-MF using a personal magnetic-field dosimeter, and the cytogenetic effects were examined by comparing micronuclei (MN) and sister chromatid exchange (SCE) frequencies in the lymphocytes of the exposed workers with those of non-exposed control subjects (blood donors) matched for age and smoking habit. Cytogenetic analyses were carried out on 21 workers enrolled from two different welding companies in Central Italy and compared to 21 controls. Some differences between the groups were observed on analysis of SCE and MN, whereas replication indices in the exposed were found not to differ from the controls. In particular, the exposed group showed a significantly higher frequency of MN (group mean ± SEM: 6.10 ± 0.39) compared to the control group (4.45 ± 0.30). Moreover, the increase in MN is associated with a proportional increase in ELF-MF exposure levels with a dose-response relationship. A significant decrease in SCE frequency was observed in exposed subjects (3.73 ± 0.21) compared to controls (4.89 ± 0.12). The hypothesis of a correlation between genotoxic assays and ELF-MF exposure value was partially supported, especially as regards MN assay. Since these results are derived from a small-scale pilot study, a larger scale study should be undertaken.     

Micronuclei induced by municipal landfill leachate in mouse bone marrow cells in vivo

The induction of micronuclei (MN) in polychromatic erythrocytes (PCE) of mouse bone marrow by municipal landfill leachate was studied in vivo. Results showed that mouse exposure via drinking water containing various concentrations of leachate caused a significant increase of MN frequencies in a concentration (Chemical oxygen demand measured with potassium dichromate oxidation, COD(Cr))-dependent manner. MN induction in female and male mice was different at higher concentrations. This implies that leachate is a genotoxic agent in mammalian cells and that exposure to leachate in an aquatic environment may pose a potential genotoxic risk to human beings.     

Investigation of the Genotoxicity of Malathion to Freshwater Teleost Fish Channa punctatus (Bloch) Using the Micronucleus Test and Comet Assay

Malathion [S-(1,2-dicarboethoxyethyl) O, O-dimethyl phosphorodithioate] is a widely used organophosphorus insecticide throughout the world. However, limited efforts have made to study its genotoxic effect in different fish tissues. The present investigation was aimed to assess the genotoxic potential of the pesticide to the freshwater teleost fish Channa punctatus at sublethal concentrations using the micronucleus test and comet assay. Initially, the 96-h LC₅₀ value of commercial-grade malathion (50% EC) was determined as 5.93 ppm in a semistatic system. Based on LC₅₀, three test concentrations (viz. sublethal I, sublethal II, and sublethal III) were determined to be 1.48, 0.74, and 0.59 ppm, respectively, and the fish specimens were exposed to these concentrations. Tissue samplings were done on days 0, 1, 3, 7, 15, 22 and 29 of malathion exposure for assessment of the induction of micronuclei (MN) frequency and DNA damage. The MN formation in the peripheral blood cells was found to be significantly higher (p < 0.05) in the treated specimens at all sampling intervals compared to the control. The MN frequency reached maximum on days 3 and 7 at sublethal I and II concentrations, respectively, followed by a nonlinear decline with the progression of the experiment. Similarly, significant effects (p < 0.05) of both concentration and time of exposure were observed on DNA damage in the gill, kidney, and lymphocytes. All of the tissues exhibited a concentration-dependent increase in DNA damage up to day 3, followed by a nonlinear decrease with the duration of exposure. A comparison of the extent of DNA damage among the tissues showed the sensitivity of gill tissue to malathion.     

Effect of sulfur dioxide hydrates on cell cycle, sister chromatid exchange, and micronuclei in barley

The effects of sulfur dioxide (SO(2)) hydrates exposure on cell cycle, sister chromatid exchange (SCE), and micronuclei (MN) were investigated in barley (Hordeum vulgare) roots. A mixture of sodium bisulfite and sodium sulfite (1:3), at various concentrations from 1x10(-5) to 3x10(-2)M, was used for the treatments. The results showed that the mixture induced the formation of SCE and MN in barley root cells with different effective concentrations and with different trends as treatment concentrations increased. At high concentrations of 0.5-30.0mM, SO(2) hydrates inhibited the mitotic activity and the growth of barley roots by cell cycle delay and cell death, but at 0.1mM, the chemicals slightly stimulated mitotic activity and root growth. These remarkable effects in causing DNA damage and consequent chromosome damage suggest that SO(2) is genotoxic agent and its genotoxicity may influence the mitotic activity and plant growth under SO(2) stress.     

Geonotoxicity study of illegal drug MDMA and its nitroso derivative N-MDMA by micronucleus and chromosomal aberration tests using Chinese hamsger lung fibroblast cell line

Objectives An increase in incidence of the illegal use of tablets containing 3,4-methylenedioxymethamphetamine hydrochloride (MDMA) has recently become a widespread social problem. MDMA ingested orally reacts with nitrite in the stomach and is synthesized intoN-nitroso-3,4-methylenedioxymethamphetamine (N-MDMA). The aim of this study is to investigate the genotoxic effects of MDMA and N-MDMA on the basis of the results of an in vitro micronucleus (MN) test and an in vitro chromosomal aberration (CA) test using a Chinese hamster lung fibroblast cell line (CHL/IU). Methods Tablets containing MDMA obtained from the Regional Bureau of the Ministry of Health, Labor and Welfare were purified, and N-MDMA was synthesized from MDMA in our laboratory. To evaluate the effects of MDMA and N-MDMA, the MN test established by our laboratory and the CA test in accordance with the guidelines for toxicity studies of drugs recommended by the Ministry of Health, Labor and Welfare were performed. Results In the MN test, no increased frequency of MNs was not found for MDMA. On the other hand, an apparently increased frequency of MNs was observed for N-MDMA. In the CA test, no CA was found for MDMA, but CA was observed for N-MDMA apparently. Conclusion N-MDMA genotoxicity was observed in the MN and CA tests. However, no MDMA genotoxicity was observed.     

Micronuclei and Other Nuclear Lesions as Genotoxicity Indicators in Rainbow Trout Oncorhynchus mykiss

The induction of micronuclei and other nuclear abnormalities in renal erythrocytes of rainbow trout Oncorhynchus mykiss by six genotoxic compounds is evaluated. Colchicine, mitomycin, cyclophosphamide, acrylamide, methyl-methanesulfonate, and N-ethyl-N-nitrosourea were intraperitoneally injected in trout. Our results show that cyclophosphamide induces the formation of micronuclei and also the other nuclear abnormalities; N-ethyl-N-nitrosourea, acrylamide, and colchicine induce only micronuclei; mitomycin-C induces only other nuclear abnormalities but not micronuclei. Methyl-methanesulfonate does not induce nuclear abnormalities in rainbow trout at the dose assayed in this work. The possible genotoxic origin for the different nuclear abnormalities is discussed.     

Genotoxic Effects of Water from São Francisco River,Brazil, in Astyanax paranae

Aquatic monitoring is an important tool for identifying potential compounds in rivers that may damage the environment. Here, we evaluate the potential genotoxic effects of water samples from São Francisco River (Brazil) using the micronuclei (MN) assay in resident species, Astyanax paranae. Four seasonal collections occurred between the years 2009 and 2010, at three locations between two nearby cities in the region. It was clearly observed an increase of MN frequency in fish caught in the river. This result is most likely due to the sewage contamination from the treatment plant, the waste pesticides from crops and the lack of riparian vegetation along the river, especially during the winter when there was a significant increase in the frequencies of MN. These results indicate that compounds in waters from São Francisco River may have genotoxic effects and consequently, cause damage to the environment as well as to human health.