Application of micronucleus test and comet assay to evaluate BTEX biodegradation

BTEX and PAH contributions to Lake Kinneret water: a seasonal-based study of volatile and semi-volatile anthropogenic pollutants in freshwater sources

Benzene , toluene, ethylbenzene, and xylenes (BTEX) BTEX molecules are toxic components, ubiquitous in the environment, often found in concentrations- a few orders of magnitude higher than the well-studied PAHs levels. This fact is demonstrated in either crude oil, fuels, water, and air samples. BTEX studies focus mainly on the airborne levels of these molecules, while their waterborne presence is understudied. In this study, BTEX levels were assessed at Lake Kinneret, Israel. As a result, 0-1.5 ppb of BTEX was recorded in five stations (2021-2022). Elevated BTEX levels (3-10 ppb) were recorded at the northern rivers nourishing this lake, implying the existence of remote polluting sources. Transect air samplings of BTEX conducted at the lake next to the bathing season of 2021 revealed airborne BTEX levels between 0.8 and 10 µg/m³, peaking up close to the bathing season, yet inconsistent with the BTEX water level trend. Lake water samples collected next to Tiberias city outfalls following the "Carmel" rainstorm showed elevated concentrations of BTEX up to 35 ppb and PAHs up to 0.47 ppb with an urban isotopic signal. The remote station's PAHs levels were less than one order of magnitude, with a distinct rural isotopic signal. Additionally, a human-specific microbial marker revealed increased sewer contributions at some of the urbansites. The results of this study show that a wide area dispersion of low atmospheric BTEX levels exists in the lake's perimeter. The dispersion rate is most likely influenced by season-based factors, e.g., motors and biomass fires. The unstudied waterborne BTEX levels in this lake are influenced by rivers, city runoff, and other yet unknown factors that may contribute to the sedimentation of these components. This process may result in a chronic pollution state. Despite the BTEX's medium-low solubility and high volatility, its under-evaluated waterborne transportation may lead to high toxic levels following bioaccumulation.

Expression level and function analysis of serum miRNAs in workers with occupational exposure to benzene series

Benzene series are ubiquitous in industrial production and daily life, and can have an impact on health even at low concentrations. miRNAs have been proved to be a biomarker of a variety of diseases and carcinogens. The purpose of this study was to explore the distribution characteristics and biological function of miRNAs in subjects exposed to benzene series. In this study, serum miRNAs were measured in 247 occupationally exposed subjects and 256 controls. The relationship between cumulative exposure dose of benzene series and miRNAs was analyzed by Generalized linear model, Spearman's rank correlation, and chi-square test for trend. The function of MiRNAs target gene was analyzed by means of bioinformatics method. The results showed that the expressions of miR-181a-5p, 221-3p, 223-3p, and 342-3p were down-regulated, whilst the expression of miR-638 was up-regulated in the occupational exposure group. miR-181a-5p, 221-3p, 223-3p, 342-3p, and 638 showed dose-response relationship with benzene series, and were closely related to multiple tumor pathways. miR-181a-5p, 221-3p, 223-3p, 342-3p, and 638 may be involved in the carcinogenic process of benzene series, and can be used to evaluate the early biological effects and monitor the exposure level of benzene series. miRNAs are potential biomarkers of benzene series exposure.

Evaluation of joint toxicity of BTEX mixtures using sulfur-oxidizing bacteria

Benzene (B), toluene (T), ethylbenzene (E), and xylenes (X) are petrochemicals vital in various industrial and commercial processing but identified as priority pollutants due to their high toxicity. The objective of this study was to investigate the toxicological nature of BTEX mixtures under controlled laboratory aquatic conditions using sulfur-oxidizing bacteria (SOB). Results from individual BTEX tests demonstrated that the order of toxicity among BTEX was X ≥ E > T > B. Comparisons of dose-effect curves for BTEX suggest that the biochemical mode of action of B in SOB was different from those of T, E, and X. Toxicological interactions of BTEX in mixtures were studied using concentration addition (CA), independent action (IA), and combination index (CI)-isobologram models. The CI model approximated the actual toxicity of BTEX mixtures better than the CA and IA models. In most cases, BTEX induced synergistic interactions in mixtures. However, in some B-containing mixtures, antagonism was observed at low effective levels. The effective level (fa)-CI plots and polygonograms illustrate that synergistic interactions of BTEX became stronger with an increase in effective levels. In addition, ternary and quaternary mixtures were found to provoke stronger synergism than binary mixtures. The present study suggests that the CI-isobologram model is a suitable means to evaluate diverse toxicological interactions of contaminants in mixtures.

Evaluating the aerobic xylene-degrading potential of the intrinsic microbial community of a legacy BTEX-contaminated aquifer by enrichment culturing coupled with multi-omics analysis: uncovering the role of Hydrogenophaga strains in xylene degradation

To develop effective bioremediation strategies, it is always important to explore autochthonous microbial community diversity using substrate-specific enrichment. The primary objective of this present study was to reveal the diversity of aerobic xylene-degrading bacteria at a legacy BTEX-contaminated site where xylene is the predominant contaminant, as well as to identify potential indigenous strains that could effectively degrade xylenes, in order to better understand the underlying facts about xylene degradation using a multi-omics approach. Henceforward, parallel aerobic microcosms were set up using different xylene isomers as the sole carbon source to investigate evolved bacterial communities using both culture-dependent and independent methods. Research outcome showed that the autochthonous community of this legacy BTEX-contaminated site has the capability to remove all of the xylene isomers from the environment aerobically employing different bacterial groups for different xylene isomers. Interestingly, polyphasic analysis of the enrichments disclose that the community composition of the o-xylene-degrading enrichment community was utterly distinct from that of the m- and p-xylene-degrading enrichments. Although in each of the enrichments Pseudomonas and Acidovorax were the dominant genera, in the case of o-xylene-degrading enrichment Rhodococcus was the main player. Among the isolates, two Hydogenophaga strains, belonging to the same genomic species, were obtained from p-xylene-degrading enrichment, substantially able to degrade aromatic hydrocarbons including xylene isomers aerobically. Comparative whole-genome analysis of the strains revealed different genomic adaptations to aromatic hydrocarbon degradation, providing an explanation on their different xylene isomer-degrading abilities.

Genetic variations in ATM and H2AX loci contribute to risk of hematological abnormalities in individuals exposed to BTEX chemicals

Background

Loci controlling DNA double‐strand breaks (DSBs) repair play an important role in defending against the harmful health effects of benzene, toluene, ethylbenzene, and xylene (BTEX), but their gene variants may alter their repair capacity. The aim of the current study was to determine the relationship of functional polymorphisms ATM‐rs228589 A>T, WRN‐rs1800392 G>T and H2AX‐rs7759 A>G in DBS repair loci with the abnormal hematological indices in workers who exposed to BTEXs.

Methods

We included 141 cases with one or more abnormal hematological parameters, who had been occupationally exposed to BTEX chemicals and 152 controls with a similar exposure condition but without any abnormal hematological parameters. Atmospheric concentrations of BTEXs were measured and whole blood samples were taken from the participants to determine hematologic parameters and SNP genotyping.

Results

Results showed that T allele of ATM‐rs228589 and G allele of H2AX‐rs7759 had a higher frequency in cases than controls (p = 0.012 and p = 0.001, respectively). Also, AT and TT genotypes of ATM‐rs228589 and AG and GG genotypes of H2AX‐rs7759 were higher in cases compared to controls. The AT and TT genotypes of ATM‐rs228589 have significant associations with a risk of hematological abnormalities in the codominant (AT vs. AA, p = 0.018), dominant (AT + TT vs. AA, p = 0.010) and overdominant (AT vs. AA + TT, p = 0.037) models. The GG and AG genotypes of H2AX‐rs7759 were in relation with increased risk of abnormal hematological indices under codominant (GA vs. AA, p = 0.009 & GG vs. AA, p = 0.005), dominant (AG + GG vs. AA, p = 0.001), and recessive (GG vs. AA + AG, p = 0.025) models.

Conclusions

These observations may help to understand the mechanisms of BTEX hematotoxicity and identify useful biomarkers of risk assessment for workers exposed to BTEX.

Biodegradation of p-xylene-a comparison of three psychrophilic Pseudomonas strains through the lens of gene expression

p-Xylene is considered a recalcitrant compound despite showing a similar aromatic structure to other BTEXs (benzene, toluene, ethylbenzene, xylene isomers). This study evaluated the p-xylene biodegradation potential of three psychrophilic Pseudomonas strains (Pseudomonas putida S2TR-01, Pseudomonas synxantha S2TR-20, and Pseudomonas azotoformans S2TR-09). The p-xylene metabolism-related catabolic genes (xylM, xylA, and xylE) and the corresponding regulatory genes (xylR and xylS) of the selected strains were investigated. The biodegradation results showed that the P. azotoformans S2TR-09 strain was the only strain that was able to degrade 200 mg/L p-xylene after 60 h at 15 °C. The gene expression study indicated that the xylE (encoding catechol 2,3-dioxygenase) gene represents the bottleneck in p-xylene biodegradation. A lack of xylE expression leads to the accumulation of intermediates and the inhibition of biomass production and complete carbon recovery. The activity of xylene monooxygenase and catechol 2,3-dioxygenase was significantly increased in P. azotoformans S2TR-09 (0.5 and 0.08 U/mg, respectively) in the presence of p-xylene. The expression of the ring cleavage enzyme and its encoding gene (xylE) and activator (xylS) explained the differences in the p-xylene metabolism of the isolated bacteria and can be used as a novel biomarker of efficient p-xylene biodegradation at contaminated sites.

Genotoxicity, oxidative stress and lysozyme induction in Clarias gariepinus chronically exposed to water-soluble fraction of burnt tire ash

The safety of aquatic ecosystems has been compromised by numerous anthropogenic activities, especially leachates from non-point source toxicants, leaching into aquatic systems. This study evaluated the toxicity of the water-soluble fractions (WSFs) of burnt tire ash (BTA) on Clarias gariepinus via a battery of integrated biomarkers. Juvenile C. gariepinus were exposed to sublethal (0.56, 1.12, and 2.24 g/L) concentrations of BTA, derived from 11.2 g/L median lethal concentration (96 LC₅₀), at duration intervals of 1, 14, and 28 days, followed by a recovery trial that lasted for 14 days. Serum biochemical parameters, antioxidant enzyme activities of the gill and liver, lysozymes activity and erythron profile were assessed. The findings of the present study revealed that BTA-WSF induced prominent alterations on biochemical parameters, lysozymes activity and antioxidant enzymes activities in the exposed fish. Furthermore, toxicant exposure promoted oxidative stress, cellular damage and genotoxicity (erythrocytic nuclear and cellular abnormalities) in the exposed fish. In general, a post-exposure trial showed partial recovery from the exposure effects of the toxicant, following the evident modifications of serum enzymes and erythron pathopathology in the experimental model. Biomonitoring of BTA, using sentinel aquatic species such as C. gariepinus, provides insights into the ecotoxicological potency of this toxicant.

Cytotoxic impacts of treated electroplating industrial effluent and the comparative effect of their metal components (Zn, Hg, and Zn+Hg) on Danio rerio gill (DrG) cell line

Effluent produced during the electroplating process can contain high concentrations of heavy metals that can enter the environment and induce toxicity to aquatic organisms. Relatively high concentrations of zinc (Zn) and mercury (Hg) have been detected in treated electroplating industrial effluent (TEPIE), though the cytotoxic potential of these compounds has not been well assessed in fish gills. A novel cell line, Danio rerio gill (DrG), were exposed to TEPIE and concentrations of Zn, Hg, and Zn + Hg previously measured in treated effluent to evaluate the use of the DrG cell line following exposure to environmental pollutants. Several cytotoxic assays were employed to assess the effect of TEPIE, Zn, and Hg on this cell line. The percent cell viability was significantly reduced in a concentration-dependent manner following exposure to TEPIE, Zn, Hg, and Zn + Hg (p < 0.05) for 24 h, with additional morphological changes observed in exposure treatments relative to controls. Additionally, there was a significant induction of DNA damage detected in all exposure treatments determined through comet assay tail length. An increase in intracellular ROS generation was also observed in cells exposed to TEPIE, Zn, Hg, and Zn + Hg, corresponding to dose-dependent increases in apoptosis. Our study confirmed that TEPIE and the metals present in it induced cytotoxicity in the DrG cell line, demonstrating its usefulness as a model to explore relationships between pollutants and fish gills.

Combine effect of exposure to petrol, kerosene and diesel fumes: On hepatic oxidative stress and haematological function in rats

Petroleum product fumes (PPFs) containing toxic organic components are pervasive in the environment, emanating from anthropogenic activities, including petroleum exploration and utilization by end-user activities from petrol-gasoline stations. Petrol station attendants are exposed to PPF through inhalation and dermal contact with consequent toxicological implications. We investigated the effects of chronic exposure (60 and 90 days) to petrol (P), kerosene (K) and diesel (D) alone and combined exposure to petrol, kerosene and diesel (PKD) fumes on hepatotoxicity, haematological function and oxidative stress in rats. Following sacrifice, we evaluated hepatic damage biomarkers, blood glucose, oxidative stress and haematological function. Chronic exposure to PPF significantly increased organo-somatic indices, blood glucose, biomarkers of hepatic toxicity and oxidative stress in an exposure duration-dependent manner. There was a simultaneous decrease in the protective capacity of antioxidants. Furthermore, exposure to PPF increased pro-inflammatory biomarkers in rats (90 > 60 days). Regardless of exposure duration, plateletcrit, mean platelet volume, platelet distribution width and red cell distribution width in the coefficient of variation increased, whereas red blood cell count, haemoglobin, packed cell volume, mean corpuscular volume, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration, white blood cell, lymphocyte, monocyte-basophil-eosinophil mixed counts and platelet count decreased after 60 and 90 days exposure. Microscopic examination of the liver demonstrated hepatic pathological changes paralleling the duration of exposure to PKD fumes. However, the injury observed was lesser to that of rats treated with the diethylnitrosamine - positive control. Our results expanded previous findings and further demonstrated the probable adverse effect on populations' health occasioned by persistent exposure to PPF. Individuals chronically exposed by occupation to PPF may be at greater risk of developing disorders promoted by continuous oxido-inflammatory perturbation and suboptimal haematological-immunologic function - thereby enabling a permissive environment for pathogenesis notwithstanding the limitation of quantifying PPF absolute values in our model system.

PBAT biodegradable mulch films: Study of ecotoxicological impacts using Allium cepa, Lactuca sativa and HepG2/C3A cell culture

Biodegradable mulch films are an alternative to polyethylene films used in agriculture for weed control, improving crop productivity. This change could minimize the residue production and costs related to the final disposal. Nevertheless, the environmental safety of these biodegradable products is scarcely investigated. In this work, samples of poly(butylene adipate-co-terephthalate)-PBAT mulch films, with and without UV stabilizer additives, were prepared. Aqueous extracts of soil samples, where mulch films were disposed, were investigated using bioassays with Lactuca sativa, Allium cepa, and cell culture HepG2/C3A. As PBAT is expected to suffer photodegradation and biodegradation, soil samples mixed with films before and after these processes were evaluated. Soil aqueous extracts promoted root grown (mainly hypocotyl) of L. sativa, probably due to presence of nutrients. So, to evaluate toxicity potential, in this case it was necessary to use aqueous extract prepared with soil instead of ultrapure water as the control. After doing this analysis it was observed that no adverse impacts due to PBAT films occurred. No chromosomal abnormalities were observed in A. cepa bioassay for any of tested samples. The absence of genotoxic potential was confirmed by comet assay and micronucleus test using human hepatocarcinoma cell line HepG2/C3A. These results showed that the soil did not induce damage to the tested organisms, before and after degradation of PBAT films.

Toxicity of a mixture of monoaromatic hydrocarbons (BTX) to a tropical marine microcrustacean

This study evaluated the toxicity of benzene, toluene, and xylenes (BTX), isolated and in binary mixtures to Mysidopsis juniae. The organisms were exposed to BTX, and combined effect patterns were predicted by applying the theoretical models of Concentration Addition and Independent Action. According to the LC50 of the isolated compounds, xylene (16.1 ± 2.4 mg L^-1) was considered the most toxic, followed by toluene (38.0 ± 5.3 mg L^-1) and, lastly, benzene (78.0 ± 2.9 mg L^-1). The binary combinations showed deviations from additivity, with exposure to the xylene-benzene mixture presenting as antagonistic, while the xylene-toluene and toluene-benzene mixtures were better explained by a dose ratio deviation, with toluene being responsible for the antagonistic pattern. This study provides new insights into toxicity prediction of a BTX mixture, which adds value to the risk assessment procedure over evaluation of chemical hazards on a case-by-case basis.

Ecotoxicity tests with Allium cepa to determine the efficiency of rice husk ash in the treatment of groundwater contaminated with benzene, toluene, ethylbenzene, and xylene

The validation of adsorption treatment based on toxicity assays aims to assess the actual environmental impact caused by effluents after treatment. This study describes the use of rice husk ash as adsorbent and evaluates the efficiency of adsorption treatment to remediate groundwater contaminated with benzene, toluene, ethylbenzene, and xylene (BTEX). The synthetic effluent was prepared with standard benzene, toluene, ethylbenzene, and xylene solutions. Adsorption was assessed at treatment times 0, 60, 120, and 240 min. Compounds were quantified by gas chromatography with flame ionization detector. The treatment was validated based on ecotoxicity assays using Allium cepa as indicator organism. For the treatment times stipulated, samples containing 25, 50, and 100% of BTEX were used. The dilutions were carried out with drinking water according to Fiskesjö (1985). The relative growth index (RGI), root inhibition index (Ii), and germination index (GI) confirmed the efficiency of the treatment approach tested. The best adsorption time for an initial BTEX concentration of 3.378 mg/L was 60 min. Critical level (EC50) and critical concentration that induced phytotoxic effect on A. cepa germination was observed only for the undiluted effluent.

Evaluation of the potential agricultural use of biostimulated sewage sludge using mammalian cell culture assays

Among the bioremediation processes, biostimulation is an effective methodology for the decontamination of organic waste by the addition of agents that stimulate the indigenous microbiota development. Rice hull is a biostimulating agent that promotes the aeration of edaphic systems and stimulates the aerobiotic activity of soil microorganisms. The present study aimed to evaluate the efficacy of the bioremediation and biostimulation processes in reducing the toxicity of sewage sludge (SS) and to evaluate its possible application in agriculture using cytotoxic and genotoxic assays in human hepatoma cells (HepG2). SS of domestic origin was tested as both the pure product (PSS) and mixed with soil (S) and with a stimulating agent, such as rice hull (RH), in different proportions (SS + S and SS + S + RH); we also examined different remediation periods (3 months - T1 and 6 months - T2). For the PSS sample, a significant induction of micronucleus (MN) in T2 was observed with nuclear buds in all of the periods assessed, and we observed the presence of more than one alteration per cell (MN and nuclear bud) in T1 and T2. The PSS sample caused genotoxic effects in the HepG2 cells even after being bioremediated. For the samples containing soil and/or rice hull, no toxic effects were observed in the test system used. Therefore, the addition of SS to agricultural soils should be conducted with caution, and it is important that the SS undergoes a remediation process, such as bioremediation and biostimulation treatments.

The influence of heavy metals on toxicogenetic damage in a Brazilian tropical river

Anthropogenic activities in tropical rivers favor the eutrophication process, which causes increased concentration of heavy metals. The presence and bioaccumulation of metals are directly related to the presence of genotoxic damage in aquatic organisms. Thus, we evaluated the presence of heavy metals (Fe, Zn, Cr, Cu and Al) and performed toxicogenetic tests in surface (S) and bottom (B) of water samples of the Poti river (Piaui/Brazil). Cytotoxicity and genotoxicity tests were performed in Allium cepa, and micronucleus (MN) and comet assay were performed in Oreochromis niloticus. The chemical analysis showed concentrations above the limit for Cu, Cr, Fe and Al according to Brazilian laws, characterizing anthropogenic disturbance in this aquatic environment. Toxicogenetic analysis presented significant cytotoxic, mutagenic and genotoxic effects in different exposure times and water layers (S and B), especially alterations in mitotic spindle defects, MN formations, nuclear bud and DNA strand breaks. Correlations between Fe and cytotoxicity, and Al and mutagenicity were statistically significant and point out to the participation of heavy metals in genotoxic damage. Therefore, Poti river water samples presented toxicogenetic effects on all bioindicators analyzed, which are most likely related to heavy metals pollution.

Physico-chemical and genotoxicity analysis of Guaribas river water in the Northeast Brazil

River pollution in Brazil is significant. This study aimed to evaluate the physico-chemical and genotoxic profiles of the Guaribas river water, located in Northeast Brazil (State of Piauí, Brazil). The study conducted during the dry and wet seasons to understand the frequency of pollution throughout the year. Genotoxicity analysis was done with the blood of Oreochromis niloticus by using the comet assay. Water samples were collected from upstream, within and downstream the city Picos. The results suggest a significant (p < 0.05) genotoxic effect of the Guaribas river water when compared to the control group. In comparison to the control group, in the river water we found a significant increase in metals such as - Fe, Zn, Cr, Cu and Al. In conclusion, Guaribas river carries polluted water, especially a large quantity of toxic metals, which may impart the genotoxic effect.

Attesting the efficiency of monitored natural attenuation in the detoxification of sewage sludge by means of genotoxic and mutagenic bioassays

A viable alternative to the use of sewage sludge (SS) would be using it as a reconditioner of agricultural soils, due to its high content of organic matter and nutrients. However, this solution may contaminate the soil, since SS may contain toxic substances. Monitored natural attenuation is a process that can be used in the decontamination of SS before its disposal into the environment. The effectiveness of the natural attenuation of a domestic SS was evaluated over 12 months by assays of Salmonella/microsome and micronucleus (MN) in human hepatoma cells (HepG2). Mutagenic activity was observed for the Salmonella strain TA 100, with S9, for the extracts from periods 0-6 months of natural attenuation. Genotoxic effects were observed in HepG2 cells, for 0 and 2 months, in almost all tested concentrations. Comparing obtained data by MN test to chemical analyses, it is possible to observe a coincidence between the induction of MN and the quantity of the m- and p-cresol, since these compounds were present in the initial SS and after 2 months of natural attenuation, decreasing their concentrations in samples from 6 to 12 months. The positive results obtained with Salmonella/microsome (from 6 months) suggest a combined action of other substances in SS. These results indicated that this SS, in the earlier periods tested, is potentially genotoxic and mutagenic and that its disposal can lead to severe environmental problems. Thus, the use of the studied SS as reconditioner requires pre-processing for over than 6 months of natural attenuation.

Air-borne xylene degradation by Bougainvillea buttiana and the role of epiphytic bacteria in the degradation

The efficiency of xylene removal from contaminated air by thirteen perennial plants was studied. The results showed that Bougainvillea buttiana had the highest xylene removal efficiency. Different parts of B. buttiana such as stems, epicuticular waxes, and plant stomata (including microorganism-associated plant leaves) can uptake xylene 53.1±1.9%, 32.3±0.9, and 14.6±0.0%, respectively. Metabolite products found in treated plants may result from stress or defense compounds triggered by exposure to xylene. Moreover, possible degradation products in B. buttiana stems were analyzed after treatment with xylene at 100 ppm. Various metabolites in B. buttiana stems such as 2,6-dimethoxyphenol, 4-hydroxy-3,5-dimethoxy benzoic acid, 1-isopropyl-4-methylbenzene, p-tolualdehyde, 2,5-dimethoxy-4-methylbenzaldehyde, 2,4-dihydroxy-2,5-dimethyl-3(2H)-furanone, 3-methyl-2-butenal, dihydroxy acetone, propanedial, and many organic acids are related to the xylene degradation pathway. In addition, microorganism-associated B. buttiana leaves especially Enterobacter cloacae LSRC11, Staphylococcus sp. A1 and Pseudomonas aeruginosa enhanced the plant resulting in quicker xylene removal.

Evaluation of the genotoxicity/mutagenicity and antigenotoxicity/antimutagenicity induced by propolis and Baccharis dracunculifolia, by in vitro study with HTC cells

The ethanolic extract of propolis, especially the Brazilian green type, is widely and mainly used for therapeutic purposes despite the lack of knowledge about its effects and its cellular mode of action. This type of propolis, derived from Baccharis dracunculifolia (alecrim-do-campo), has been extensively commercialized and the consumers use it to enhance health. This work aimed to assess the genotoxic/mutagenic and antigenotoxic/antimutagenic potentials of the ethanolic extracts of Brazilian green propolis and of B. dracunculifolia, on mammalian cells. It was not observed genotoxic and mutagenic effects by both extracts. After evaluate the exposure of the cells to each extract with a recognized mutagen, simultaneously, the results showed a significant reduction on DNA damage. The experiment carried out with a pre-incubation period was more effective than without incubation test, showing that the tested extracts were able to inactivate the mutagen before it could react with the DNA.

DNA damage and cytotoxicity in pathology laboratory technicians exposed to organic solvents

The aim of this study was to evaluate potential DNA damage and cytotoxicity in pathology laboratory technicians exposed to organic solvents, mainly xylene. Peripheral blood and buccal cells samples were collected from 18 technicians occupationally exposed to organic solvents and 11 non-exposed individuals. The technicians were sampled at two moments: Monday and Friday. DNA damage and cytotoxicity were evaluated using the Comet Assay and the Buccal Micronucleus Cytome assay. Fifteen subjects (83.5%) of the exposed group to solvents complained about some symptom probably related to contact with vapours of organic solvents. DNA damage in the exposed group to solvents was nearly 2-fold higher on Friday than on Monday, and in both moments the individuals of this group showed higher levels of DNA damage in relation to controls. No statistical difference was detected in buccal cell micronucleus frequency between the laboratory technicians and the control group. However, in the analysis performed on Friday, technicians presented higher frequency (about 3-fold) of karyolytic and apoptotic-like cells (karyorrhectic and pyknotic) in relation to control group. Considering the damage frequency and the working time, a positive correlation was found in the exposed group to solvents (r=0.468; p=0.05). The results suggest that pathology laboratory workers inappropriately exposed to organic solvents have increased levels of DNA damage.

Analysis of the genotoxic potential of low concentrations of Malathion on the Allium cepa cells and rat hepatoma tissue culture

Based on the concentration of Malathion used in the field, we evaluated the genotoxic potential of low concentrations of this insecticide on meristematic and F1 cells of Allium cepa and on rat hepatoma tissue culture (HTC cells). In the A. cepa, chromosomal aberrations (CAs), micronuclei (MN), and mitotic index (MI) were evaluated by exposing the cells at 1.5, 0.75, 0.37, and 0.18mg/mL of Malathion for 24 and 48hr of exposure and 48hr of recovery time. The results showed that all concentrations were genotoxic to A. cepa cells. However, the analysis of the MI has showed non-relevant effects. Chromosomal bridges were the CA more frequently induced, indicating the clastogenic action of Malathion. After the recovery period, the higher concentrations continued to induce genotoxic effects, unlike the observed for the lowest concentrations tested. In HTC cells, the genotoxicity of Malathion was evaluated by the MN test and the comet assay by exposing the cells at 0.09, 0.009, and 0.0009mg/5mL culture medium, for 24hr of exposure. In the comet assay, all the concentrations induced genotoxicity in the HTC cells. In the MN test, no significant induction of MN was observed. The genotoxicity induced by the low concentrations of Malathion presented in this work highlights the importance of studying the effects of low concentrations of this pesticide and demonstrates the efficiency of these two test systems for the detection of genetic damage promoted by Malathion.

Fast identification and quantification of BTEX coupling by Raman spectrometry and chemometrics

Monoaromatic hydrocarbons (MAHs) monitoring is of environmental interest since these chemical pollutants are omnipresent.

Evaluation of the genotoxicity of waters impacted by domestic and industrial effluents of a highly industrialized region of São Paulo State, Brazil, by the comet assay in HTC cells

The problems that most affect the quality of the waters of rivers and lakes are associated with the discharges performed in these environments, mainly industrial and domestic effluents inappropriately treated or untreated. The comet assay is a sensitive tool and is recommended for studies of environmental biomonitoring, which aim to determine the genotoxicity potential of water pollutants. This study aimed to assess the genotoxic potential of the Ribeirão Tatu waters, region of Limeira, São Paulo (SP), by the comet assay with mammalian cells (hepatoma tissue culture (HTC)). Water samples were collected along the Ribeirão Tatu at three distinct periods: November 2008, February 2009 and August 2009, and five collection sites were established: P1, source of the stream; P2, site located downstream the urban perimeter of the municipality of Cordeirópolis and after receiving the pollution load of this city; P3, collection site located upstream the urban perimeter of the city of Limeira; P4, urban area of Limeira; and P5, rural area of Limeira, downstream the discharges of the city sewage. The results showed that for the November 2008 collection, there was no water sample-induced genotoxicity; for the February 2009 collection, the sites P1 and P2 were statistically significant in relation to the negative control (NC), and for the August 2009 collection, the site P5 was statistically significant. These results could be explained by the content of different metals during the different seasons that are under the influence of domestic, industrial and agricultural effluents and also due to the seasonality, since the water samples collected in the period of heavy rain (February 2009) presented a higher genotoxicity possibly due to the entrainment of contaminants into the bed of the stream promoted by the outflow of rainwaters. The comet assay showed to be a useful and sensitive tool in the evaluation of hydric resources impacted by pollutants of diverse origins, and a constant monitoring should be done in order to verify the influence of different factors (season, amount of contaminants) in the water quality.