Mutagenicity and genotoxicity assessment of industrial wastewaters

Toxicogenetic profile of the monoterpene alpha-terpineol on normal and tumor eukaryotic cells

Alpha-terpineol is a monoterpene alcohol found in essential oils from medicinal plants with some well-known pharmacological activities and widely used in cosmetics. However, the toxicological effects and additional pharmacological activities need to be clarified. Thus, the study evaluated the toxic, cytotoxic, genotoxic, hemolytic, and oxidative potential of alpha-terpineol in non-clinical bioassays. Different concentrations of alpha-terpineol were used in bioassays, including MTT (50, 100, 200, and 400 μg/mL), Artemia salina (6.25-400 μg/mL), Allium cepa (10, 50, and 100 μg/mL), comet assay (100, 200, and 500 μg/mL), cytokinesis-block micronucleus (100, 250, and 500 μg/mL), confocal microscopy for apoptosis quantification (100 and 500 μg/mL), hemolysis and Saccharomyces cerevisiae central disk test (10, 35, and 75 μg/mL). For the MTT test, alpha-terpineol was more cytotoxic on melanoma murine B16-F10 cells rather than macrophages. For A. salina test, alpha-terpineol showed LC50 of 68.29 and 76.36 μg/mL for 24 h and 48 h of exposure time, respectively. Meanwhile, alpha-terpineol was also cytotoxic to meristematic cells, which revealed inhibition of cellular division and mutagenic action by formation of bridges and delayed anaphases. The compound increased damage index and frequency of damage corroborated by the presence of micronuclei, bridges and nuclear buds at 500 μg/mL, but it caused neither hemolysis, oxidative damage on the S. cerevisiae nor cell death in normal fibroblasts. The findings indicate alpha-terpineol has cytotoxic potential by cytogenetic and molecular mechanisms associated with apoptosis and probable target effects against melanoma cells.

Bacterial worth in genotoxicity assessment studies

Bacterial-based genotoxicity test systems play a significant role in the detection and evaluation of genotoxicity in vitro and have gained importance due to attributes like wide applicability, speed, high sensitivity, good reproducibility, and simplicity. The Salmonella microsomal mutagenicity assay was created by Ames and colleagues at the beginning of the 1970s, and it was based on the fundamental notion that in auxotrophic bacterial strains with inhibited growth, a mutant gene would revert to its original state on exposure to genotoxicants. This is the most successful and widely used in vitro genotoxicity test. Later, a number of additional test systems that incorporated DNA repair mechanisms including the bacterial SOS response were created. Genetic engineering has further provided significant advancement in these test systems with the development of highly sophisticated bacterial tester strains with significantly increased sensitivity to evaluate the chemical nature of hazardous substances and pollutants. These bacterial bioassays render an opportunity to detect the defined effects of compounds at the molecular level. In this review, all the aspects related to the bacterial system in genotoxicity assessment have been summarized and their role is elaborated concerning real-time requirements and future perspectives.

Genotoxicity and mutagenicity in blood and drinking water induced by arsenic in an impacted gold mining region in Colombia

Arsenic (As) is one of the most dangerous substances that can affect human health and long-term exposure to As in drinking water can even cause cancer. The objective of this study was to investigate the concentrations of total As in the blood of inhabitants of a Colombian region impacted by gold mining and to evaluate its genotoxic effect through DNA damage by means of the comet assay. Additionally, the concentration of As in the water consumed by the population as well as the mutagenic activity of drinking water (n = 34) in individuals were determined by hydride generator atomic absorption spectrometry and the Ames test, respectively. In the monitoring, the study population was made up of a group of 112 people, including inhabitants of four municipalities: Guaranda, Sucre, Majagual, and San Marcos from the Mojana region as the exposed group, and Montería as a control group. The results showed DNA damage related to the presence of As in blood (p < 0.05) in the exposed population, and blood As concentrations were above the maximum allowable limit of 1 μg/L established by the ATSDR. A mutagenic activity of the drinking water was observed, and regarding the concentrations of As in water, only one sample exceeded the maximum permissible value of 10 μg/L established by the WHO. The intake of water and/or food containing As is potentially generating DNA damage in the inhabitants of the Mojana region, which requires surveillance and control by health entities to mitigate these effects.

Cyto-genotoxic potential of petroleum refinery wastewater mixed with domestic sewage used for irrigation of food crops in the vicinity of an oil refinery

Petroleum refinery wastewater combined with domestic sewage were collected from the open channel in the vicinity of Mathura oil refinery, UP (India) and analysed by inductively coupled plasma optical emission spectrometry (ICP-OES) and gas chromatography-mass spectrometry (GC-MS) for elemental analysis and organic pollutants, respectively. Several potentially toxic and non-toxic elements were found to be present in the wastewater samples. GC-MS analysis revealed the presence of several organic contaminants including pesticides. Wastewater samples were extracted using amberlite XAD4/8 resins and liquid-liquid extraction procedures using different organic solvents. The extracts were tested for their cyto-genotoxic potential using bacterial (Salmonella mutagenicity test, E. coli K-12 DNA repair defective mutants, Bacteriophage λ assay) and plant (Vigna mungo phytotoxicity test, Allium cepa chromosomal aberration assay) systems. A significant increase was observed in the number of revertants of TA97a, TA98 and TA100 strains with the test samples and XAD concentrated samples were found to be more mutagenic than liquid-liquid extracts. Colony forming units (CFUs) of DNA repair defective mutants of E. coli K-12 recA, lexA and polA declined significantly as compared to their isogenic wild-type counterparts with the test samples. Significant reduction in plaque forming units (PFUs) of bacteriophage λ was also found on treatment with the solvent extracts. Presence of several toxic pollutants in the wastewater apply prohibitive action on the seed germination process. Germination rate of Vigna mungo seeds as well as radicle and plumule lengths were found to be affected when treated with different concentration of wastewater as compared to control. Present study also indicated concentration dependent reduction in mitotic index of A. cepa i.e., 16.38% at 5% and 9.74% at 100% wastewater and percentage of aberrant cells were highest at 100% effluent. Present findings indicated that mutagenicity/genotoxicity of wastewater is due to the mixture of genotoxins; poses serious hazards to the receiving waterbodies which require continuous monitoring and remedial measures for their improvement.

Evaluation of the raw water quality: physicochemical and toxicological approaches

Environmental degradation has increased, mainly as a result of anthropogenic effects arising from population, industrial and agricultural growth. Water pollution is a problem that affects health, safety and welfare of the whole biota which shares the same environment. In Goiânia and metropolitan region, the main water body is the Meia Ponte River that is used for the abstraction of water, disposal of treated wastewater and effluents. In addition, this river receives wastewater from urban and rural areas. The aim in this present study was to evaluate the quality of raw water by some physical, chemical and toxicological tests. The physicochemical results found high levels of turbidity, conductivity, aluminum, phosphorus and metal iron, manganese, copper and lithium when compared to the standards of the Brazilian legislation. The values found of toxicity demonstrated a high degree of cytotoxicity and genotoxicity. Therefore, it was concluded that the Meia Ponte River has been undergoing constant environmental degradation, causing the poor quality of its waters. Thus, measures for the prevention and recovery should be adopted for the maintenance of the Meia Ponte River.

Mutagenicity, genotoxicity and oxidative stress induced by pesticide industry wastewater using bacterial and plant bioassays

Atomic absorption spectrophotometer and gas chromatography analysis revealed the presence of heavy metals, organochlorine and organophosphate pesticides in industrial wastewater. XAD, Dichloromethane and n-Hexane extracted wastewater were analysed for genotoxic potential using Ames Salmonella/mammalian microsome test. The XAD concentrated sample displayed remarkable mutagenic activity compared to solvent assisted liquid-liquid extraction. Strain TA98 was found utmost sensitive towards all extracts. Wastewater induced chromosomal aberrations in roots of Allium cepa showed significant (p < 0.05) decrease in mitotic index. Seeds of Vigna radiata germinated on soft agar plates treated with different concentration of wastewater showed significant reduction in germination (52 %), seedling vigor index (76 %), radicle length (56 %), plumule length (47 %), biomass of radicle (64 %) and plumule (57%) at highest wastewater concentration. Propidium iodide stained V. radiata roots showed oxidative stress induced by wastewater under CLS microscopy. Further, genotoxicity of wastewater was confirmed by plasmid nicking assay using pBR322 plasmid.

Mutagenicity and genotoxicity evaluation of textile industry wastewater using bacterial and plant bioassays

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XAD concentrated sample was more mutagenic than the liquid-liquid extracted samples.

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TA98 was the most responsive strain, indicating presence of frameshift mutagens in textile effluent.

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Cell damage was found to be maximum in case of polA mutants (SOS defective mutants).

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The wastewater contained cytotoxic chemicals that resulted in reduction of mitotic index.

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The sample also induced chromosomal aberrations in the root meristematic cells of A. cepa.

Textile industrial wastewater samples were taken from the Panki site 5 industrial area of Kanpur city, India. Atomic Absorption spectrophotometer and Gas Chromatography-Mass spectrometry techniques have shown that the wastewater contained several heavy metals and organic pollutants (Khan and Malik, 2017) [1]. Further, in order to explore the potential toxicity of these pollutants present in the effluent, a battery of short-term biological assays (Ames test, DNA repair defective mutation assay and Allium cepa chromosomal aberration test) were used. Wastewater samples were concentrated with XAD-4/8 resins and liquid-liquid extraction procedure. XAD-concentrated samples were more mutagenic than the liquid-liquid extracted samples. Ames TA98 and polA (SOS defective) strains were the most responsive strains. The wastewater also resulted in significant decline in mitotic index and induced chromosomal aberrations in A. cepa roots. The findings thus showed that the combination of physico-chemical analysis alongwith the toxicity assessment (using short term biological assays) would provide valuable and more realistic information about the joint toxicity of chemical pollutants present in the textile effluent.

Enhanced degradation of micropollutants by zero-valent aluminum activated persulfate: assessment of toxicity and genotoxic activity

Advanced oxidation of the aqueous Triton™ X-45 (TX-45), iopamidol (IOPA), ciprofloxacin (CIP) and bisphenol A (BPA) solutions via activation of persulfate (PS) with zero-valent aluminum (ZVA) was investigated. The study aimed at assessing the effectiveness of the PS/ZVA process in terms of target micropollutants (MPs) and toxicity abatements in raw surface water (RSW) and distilled water (DW). TX-45, CIP and BPA were completely degraded after 90-minute, 120-minute and 40-minute treatment, respectively, with PS/ZVA in DW, whereas 95% IOPA removal was achieved after 120-minute (MPs = 2 mg/L; ZVA = 1 g/L; PS = 0.25 mM for CIP and BPA; PS = 0.50 mM for TX-45 and IOPA; pH = 3). TX-45 (59%), IOPA (29%), CIP (73%) and BPA (46%) removal efficiencies decreased after 120-minute PS/ZVA treatment in RSW. In DW, Vibrio fischeri toxicities of original (untreated) MPs were found as: CIP (51%) > BPA (40%) > TX-45 (15%) > IOPA (1%), and as BPA (100%) > CIP (66%) > IOPA (62%) > TX-45 (35%) in RSW. Acute toxicities of MPs and their degradation products fluctuated during PS/ZVA treatment both in DW and RSW samples and resulted in different relative inhibition values after 120-minute. The original and PS/ZVA-treated TX-45, IOPA and BPA in DW exhibited neither cytotoxic nor genotoxic effects, whereas CIP oxidation ended up in degradation products with genotoxic effects.

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.

Cytotoxicity and genotoxicity of Guaribas river water (Piauí, Brazil), influenced by anthropogenic action

In general, tropical rivers have a great impact on human activities. Bioaccumulation of toxins is a worldwide problem nowadays and has been, historically, overlooked by the supervisory authorities. This study evaluated cytogenotoxic effects of Guaribas river (a Brazilian river) water during dry and rainy seasons of 2014 by using the Allium cepa test system. The toxicogenetic variables, including root growth, mitotic index, and chromosomal aberrations, were analyzed in meristematic cells of A. cepa exposed to water samples taken from the up-, within, and downstream of the city Picos (state: Piauí). The physical-chemical parameters were also analyzed to explain water quality and possible anthropogenic action. Additionally, the presence of heavy metals was also analyzed to explain water quality and possible damaging effects on eukaryotic cells. The results suggest that the river water exerted cytotoxic, mutagenic, and genotoxic effects, regardless of the seasons. In addition, Guaribas river presented physico-chemical values outside the Brazilian laws, which can be a characteristic of human pollution (domestic sewage, industrial, and local agriculture). The genetic damage was positively correlated with higher levels of heavy metals. The pollution of the Guaribas river water may link to the chemical contamination, including the action of heavy metals and their impacts on genetic instability in the aquatic ecosystem. In conclusion, necessary steps should be taken into account for further toxicogenetic studies of the Guaribas river water, as it has an influence in human health of the same region of Brazil.

Mutagenicity of cigarette butt waste in the bacterial reverse mutation assay: The protective effects of β-caryophyllene and β-caryophyllene oxide

Cigarette filters pose a serious litter and toxic waste disposal problem, because of their not biodegradability and to the leaching of toxins in the environment. Therefore, cigarette butts need to be manipulated as special waste, with potential risks to human health and environment. In the present study, the genotoxic potential of a methanol extract from commonly discharged cigarette butts (CBE) was evaluated in the bacterial reverse mutation assay on Salmonella typhimurium TA98 and TA100 and Escherichia coli WP2uvrA strains, both in the absence and presence of the S9 exogenous metabolic activator. Furthermore, the ability of the natural sesquiterpenes β-caryophyllene (CRY) and β-caryophyllene oxide (CRYO) to inhibit the mutagenicity of CBE was studied as a possible preventive strategy. In order to identify the potential antimutagenic mechanisms, three different protocols (pretreatment, cotreatment, and posttreatment) were applied. CBE showed to increase the number of revertant colonies in all the strains tested in presence of S9, so resulting mutagenic. In the antimutagenicity assay, both CRY and CRYO significantly reduced the revertant colonies induced by CBE, although with different potency and specificity. For both sesquiterpenes, the antimutagenicity was strong in all experimental conditions, except for the cotreatment of CRY with CBE in WP2uvrA, which produced a moderate inhibition. Both desmutagenic and bioantimutagenic mechanisms seem to be involved in the antimutagenicity of the test substances. Taking into account the potential genotoxicity of cigarette butts, CRY and CRYO appear as possible further candidates as environmental decontaminants against this hazardous waste. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1319-1328, 2016.

Genotoxicity reduction in bagasse waste of sugar industry by earthworm technology

The aim of the present study was to assess the genotoxicity reduction in post vermicompost feed mixtures of bagasse (B) waste using earthworm Eisenia fetida. The genotoxicity of bagasse waste was determined by using Allium cepa root chromosomal aberration assay. Bagasse was amended with cattle dung in different proportions [0:100 (B0) 25:75 (B25), 50:50 (B50), 75:25 (B75) and 100:0 (B100)] on dry weight basis. Genotoxic effects of initial and post vermicompost bagasse extracts were analysed on the root tips cells of Allium cepa. Root length and mitotic index (MI) was found to be increased in post vermicompost extracts when compared to initial bagasse waste. The maximum percent increase of root length was observed in the B50 bagasse extract (96.60 %) and the maximum MI was observed in B100 mixture (14.20 ± 0.60) 6 h treatment which was similar to the control. Genotoxicity analysis of post vermicompost extracts of bagasse revealed a 21-44 % decline in the aberration frequencies and the maximum reduction was found in B75 extract (44.50 %). The increase in root length and mitotic index, as well as decrease in chromosomal aberrations indicates that E. fetida has the ability to reduce the genotoxicity of the bagasse waste.

The assessment of WWTP performance: Towards a jigsaw puzzle evaluation?

A chemical and bio-analytical protocol is proposed as a holistic monitoring framework for the assessment of WWTPs (Wastewater Treatment Plants) performance. This combination of tests consists of: i) an analysis of emerging contaminants, to be added to the established physico-chemical parameters in order to understand the causes of (new) pollution phenomena and ii) some of the bio-analytical tools most widely applied in the field of wastewater research, which provide information on groups of chemicals with a common mode of toxic action (baseline toxicity, estrogenicity and mutagenicity/genotoxicity, selected as the most representative for human health). The negative effects of the discharge can thus be highlighted directly and used to assess the global environmental impact of WWTPs. As a validation, this multi-tiered approach was applied to a full-scale WWTP (150,000 p.e.), where different measurements were carried out: EDCs (Endocrine Disrupting Compounds) detection; algal growth inhibition, bioluminescence inhibition and acute toxicity test (for baseline toxicity); an E-Screen-like assay (for estrogenic activity); Ames, Allium cepa and Comet tests (for mutagenic/genotoxic activity). As a result, the WWTP showed good performance for all these issues, displaying its ability to enhance effluent quality, except for residual mutagenic behaviour, probably due to the by-products generated by the tertiary ozonation.

Phthalate esters contamination in soils and vegetables of plastic film greenhouses of suburb Nanjing, China and the potential human health risk

The contamination of phthalate esters (PAEs) has become a potential threat to the environment and human health because they could be easily released as plasticizers from the daily supply products, especially in polyethylene films. Concentration levels of total six PAEs, nominated as priority pollutants by the US Environmental Protection Agency (USEPA), were investigated in soils and vegetables from four greenhouse areas in suburbs of Nanjing, East China. Total PAEs concentration ranged from 930 ± 840 to 2,450 ± 710 μg kg(-1) (dry weight (DW)) in soil and from 790 ± 630 to 3,010 ± 2,130 μg kg(-1) in vegetables. Higher concentrations of PAEs were found in soils except in Suo Shi (SS) area and in vegetables, especially in potherb mustard and purple tsai-tai samples. Risk assessment mainly based on the exposures of soil ingestion and daily vegetable intake indicated that bis(2-ethylhexyl) phthalate (DEHP) in the samples from Gu Li (GL) and Hu Shu (HS) exhibited the highest hazard to children less than 6-year old. Therefore, the human health risk of the PAEs contamination in soils and vegetables should greatly be of a concern, especially for their environmental estrogen analog effects.

Genotoxic assessment and optimization of pressmud with the help of exotic earthworm Eisenia fetida

Genotoxicity of pressmud (PM) to Allium cepa was investigated to assess its toxic potential and to elucidate the effect of vermicomposting to reduce its toxicity. The PM produced as a waste by product of the sugar cane industry was mixed with cow dung (CD) at different ratios of 0:100 (V₀), 25:75 (V₂₅), 50:50 (V₅₀), 75:25 (V₇₅) and 100:0 (V100) (PM:CD) on a dry weight basis for vermicomposting with Eisenia fetida. Different concentrations of 100% PM sludge extract (10%, 20%, 40%, 60%, 80% and 100%) and negative control (distilled water) and positive control (maleic hydrazide) were analyzed with A. cepa assay to evaluate frequency of chromosomal aberrations before and after vermicomposting. Percent aberration was greatest (30.8%) after exposure to 100% PM extract after 6 h but was reduced to 20.3% after vermicomposting. Exposure to the extract induced c-mitosis, delayed anaphase, laggards, stickiness and vagrant aberrations. Microscopic examination of root meristem exposed to PM sludge extract showed significant inhibition of mitotic index. Also, the mitotic index decreased with increase in concentration of PM sludge extract. After vermicomposting the mitotic index was increased. However, increasing percentages of PM significantly affected the growth and fecundity of the worms and maximum population size was reached in the 25:75 (PM:CD) feed mixture. Nitrogen, phosphorus, sodium, electrical conductivity (EC) and pH increased from initial feed mixture to the final products (i.e., vermicompost), while organic carbon, C/N ratio and potassium declined in all products of vermicomposting. Scanning electron microscopy (SEM) was recorded to identify the changes in texture with numerous surface irregularities and high porosity that proves to be good vermicompost manure. It could be concluded that vermicomposting could be an important tool to reduce the toxicity of PM as evidenced by the results of genotoxicity.