Evaluation of the cytotoxic and genotoxic potential of water from the River Paraíba do Sul, in Brazil, with the Allium cepa L. test

A comprehensive overview on solid waste leachate effects on terrestrial organisms

Leachate is a highly complex waste with high toxicological potential that poses a significant threat to the terrestrial environment. Determining leachate physicochemical parameters and identifying xenobiotics alone is, however, not enough to determine the real environmental impacts. In this context, the use of terrestrial model organisms has been highlighted as a tool in ecotoxicological leachate assessments and as a guiding principle in risk assessments. In this context, this review aimed to present the most current state of knowledge concerning leachate toxicity and the bioassays employed in this evaluation concerning terrestrial plants and animals. To this end, a literature search on leachate effects on terrestrial organisms was carried out using ten search terms, in 32 different combinations, at the Web of Science and Scopus databases. A total of 74 eligible articles were selected. The retrieved studies analyzed 42 different plant and animal species and employed nine endpoints, namely phytotoxicity, genotoxicity, bioaccumulation, antioxidant system, cytotoxicity, reproduction, physiological changes, behavior and lethality. A frequent association of toxic leachate effects with metals was observed, mainly Pb, Cd, Cr, Mg, Zn and Cr, which can cause antioxidant system alterations and cyto- and genotoxicity. These elements have also been associated to reproductive effects in earthworms and mice. Specifically concerning plants, most of the retrieved studies employed Allium cepa in toxicity assays, reporting phytotoxic effects frequently associated to metals and soil parameter changes. Animal studies, on the other hand, mostly employed mice and evaluated genotoxicity and antioxidant system effects. Even with the description of toxic leachate effects in both plants and animals, a lack of knowledge is still noted concerning reproductive, physiological, cytotoxic, and behavioral effects in terrestrial species. We, thus, suggest that further studies be carried out on other animals, advancing our understanding on potential environmental leachate effects, also allowing for human health risk assessments.

Impact of Arieş River Contaminants on Algae and Plants

The Arieş River (Western Romania) represents one of the most important affluents of the Mureş River, with great significance in the Mureş Tisza basin. The environmental quality of the Arieş basin is significantly affected by both historic mining activities and contemporary impacts. Thus, an evaluation of the effects of the main contaminants found in water (organochlorine pesticides-OCPs, monocyclic aromatic hydrocarbons-MAHs, polycyclic aromatic hydrocarbons-PAHs, and metals) on cyanobacteria and plants was performed. Among OCPs, hexachlorocyclohexane isomers, dichlorodiphenyltrichloroethane, and derivatives were detected in plants while admissible concentrations were detected in water. Among MAHs, high levels of benzene were detected both in water and in plants. The levels of PAHs exceeded the allowable values in all samples. Increased concentrations of metals in water were found only at Baia de Arieş, but in plants, all metal concentrations were high. The pH, nitrates, nitrites, and phosphates, as well as metals, pesticides, and aromatic hydrocarbons, influenced the physiological characteristics of algae, test plants, and aquatic plants exposed to various compounds dissolved in water. Considering that the Arieş River basin is the site of intense past mining activities, these data provide information about the impact on water quality as a consequence of pollution events.

Genotoxicity of surface waters in Brazil

Brazil has abundant surface water resources, huge aquatic biodiversity and is home to 213 million people. Genotoxicity assays are sensitive tools to detect the effects of contaminants in surface waters and wastewaters, as well as to determine potential risks of contaminated waters to aquatic organisms and human health. This work aimed to survey the articles published in 2000-2021 that evaluated the genotoxicity of surface waters within Brazilian territory to unveil the profile and trends of this topic over time. In our searches, we considered articles focused on assessing aquatic biota, articles that conducted experiments with caged organisms or standardized tests in the aquatic sites, as well as articles that transported water or sediment samples from aquatic sites to the laboratory, where exposures were performed with organisms or standardized tests. We retrieved geographical information on the aquatic sites evaluated, the genotoxicity assays used, the percentage of genotoxicity detected, and, when possible, the causative agent of aquatic pollution. A total of 248 articles were identified. There was a trend of increase in the number of publications and annual diversity of hydrographic regions evaluated over time. Most articles focused on rivers from large metropolises. A very low number of articles were conducted on coastal and marine ecosystems. Water genotoxicity was detected in most articles, regardless of methodological approach, even in little-studied hydrographic regions. The micronucleus test and the alkaline comet assay were widely applied with blood samples, mainly derived from fish. Allium and Salmonella tests were the most frequently used standard protocols. Despite most articles did not confirm polluting sources and genotoxic agents, the detection of genotoxicity provides useful information for the management of water pollution. We discuss key points to be assessed to reach a more complete picture of the genotoxicity of surface waters in Brazil.

Evaluation of effect of hazardous contaminants in areas for the abstraction of drinking water

The lower portion of Taquari River is influenced by compounds from anthropic activities causing concern about the drinking water supplied to cities in the region. The study objective was to investigate the presence of contaminants at drinking water abstraction sites, defining the mutagenic effects of these stressors as an ecosystem quality parameter and its possible effects on human health. Geographic Information System techniques were used to investigate sources of contamination and it was found that agricultural activities predominated with a few medium and high potential pollutant agricultural activities, besides a soil area that was contaminated and undergoing an intervention process. Mutagenic effects were evaluated by Salmonella/microsome assay using TA98, TA97a, TA100, YG1041 and YG1042 strains in the presence and absence of metabolic activation (S9). Mutagenesis found in organic sediment extracts and surface water samples showed the prevalence of direct-acting mutagens at the drinking water abstraction sites. Taquari (Ta032, the sampling points were named according to the initial letters of the river (Ta), followed by the number of kilometers from the mouth) showed the highest mutagenic potency in sediment, while Ta063, at Bom Retiro do Sul, presented it in the water sample. In the Triunfo region (Ta011) there were significant responses in sediment and in water samples. The samples at General Câmara (Ta006) showed the least presence of contaminants. The Allium cepa test applied to sediments in natura showed significant micronucleus induction in Ta032 in accordance with the Salmonella/microssome assay. The test performed on Danio rerio embryos (FET) in the in natura water samples did not present significant responses. Chemical analyses of polycyclic aromatic hydrocarbons and metals already identified as chemical markers in the area indicated a small contribution to the mutagenic potency, calling attention to the fact that other direct-acting pollutants may be present at the drinking water abstraction sites.

Toxicological study of aqueous-methanol solvent fraction of methanol extract of Dacryodes edulis leaves

Dacryodes edulis (G. Don) H.J. Lam) is the most popular species under the genus Dacryodes. It is well known for its nutritional and ethno-medicinal uses in South-eastern and South-western Nigeria. This study was aimed to evaluate the toxicity of the aqueous-methanol fraction of crude methanol extract of Dacryodes edulis leaves (AMDE). The test rats were randomized to groups of single oral treatment of AMDE (10-5000 mg/kgbw) for the acute toxicity study. They were monitored for obvious signs of behavioural change and mortality. For the subacute toxicity study, the rats were randomized to three daily treatment groups (of 200, 400 and 600 mg/kgbw of AMDE) for 28 days. The fourth group (control) received 2.5 %v/v DMSO. At the end of the experiment, blood samples were collected for hematology and clinical chemistry evaluation. The histopathology of the livers and kidneys were assessed using the excised organs. The cytotoxicity and genotoxicity of AMDE were also evaluated using Allium cepa model. The result showed that acute administration of AMDE, up to a dose of 5000 mg/kgbw did not result in mortality of the test rats. The observed median lethal dose (LD50) was greater than 5000 mg/kgbw. The subacute oral administration of AMDE for 28 days showed no significant (p > 0.05) effect on liver function, kidney function indices, organ - body weight ratio, but significantly (p < 0.05) decreased erythrocytic indices: red blood cells, haematocrit, and haemoglobin at 600 mg/kgbw. The Allium cepa assay revealed a non-significant reduction in mitotic index and low chromosomal aberrations of the treated groups. In conclusion, the aqueous-methanol solvent fraction of methanol extract of Dacryodes edulis leaves, AMDE is relatively safe. However, there are strong indications that it may contain compounds that are cytotoxic and reduces erythrocytic indices including red blood cells at high doses. Thus, adequate care should be taken in dosing and administering the extract to avert anaemic condition.

Assessment of surface water using Allium cepa test and histological analysis in Rhamdia quelen

This study aimed to assess the cytotoxic, genotoxic, and mutagenic potentials of water samples collected in the Alegre River Basin, located in a predominantly rural area with no sewage treatment facilities in the Espírito Santo State, Brazil, using Allium cepa test. Also, gills and liver of Rhamdia quelen, a common fish species of the region, were histologically analyzed. A semi-quantitative analysis was performed and a histopathological alterations index (HAI) was determined. Our findings indicated that the waters of this river basin were cytotoxic (mitotic index reduction) and/or genotoxic (chromosomal abnormalities induction). Mutagenicity (micronuclei induction) was not observed for any water sample. The values for HAI showed that the waters caused moderate histological alterations in R. quelen. Liver was more sensitive than gills. It is necessary to implement a sewage treatment system and raise awareness on inappropriate management and disposal of agrochemicals in order to allow the recovery of Alegre River.

Antimitotic and antimutagenic action of the Hymenaea stigonocarpa bark on dividing cells

Abstract The objective of this study was to evaluate the action of Hymenaea stigonocarpa bark hydroalcoholic extract against a mutagenic compound using A. cepa meristematic root cells as a test system. The treatment groups were: Negative Control (NC) – distilled water; Positive Control (PC) – paracetamol at a concentration of 0.008 mg/mL, Jatoba Control (JC) – aqueous fraction jatobá-do-cerrado at 0.5 or 1.0 or 1.5 mg/mL, and Simultaneous Treatment (ST) - jatobá-do-cerrado aqueous fraction at a concentration of 0.5 or 1.0 or 1.5 mg/mL associated with paracetamol solution at a concentration of 0.008 mg/mL. All groups were analyzed at 24 and 48 h. Five onion bulbs (five replications) were used for each treatment group. The root tips were fixed in Carnoy and slides prepared by the crush technique. Cells were analyzed throughout the cell cycle, totaling 5,000 for each treatment group at each exposure time. Mitotic indices were subjected to statistical analysis using the chi-square test (p<0.05). From the results it was found that the ST group, at the three concentrations, significantly potentiated the antiproliferative effect of the test system cells when compared to PC, NC and TJ at the three concentrations. Furthermore, the three ST concentrations significantly reduced the number of cell aberrations when compared to the number of aberrant cells obtained for the PC, demonstrating antimutagenic action on the A. cepa test system cells.

Monitoring Genotoxicity Potential in the Mumbuca Stream, Minas Gerais, Brazil

Rivers are sites for water catchment to supply metropolitan areas but also serve as receptors for discharge of urban sewage, wastewater, and agri-industrial effluents. Bioindicators or sentinel organisms are widely used as markers of pollution in various environments. The objective of this study was to evaluate the genotoxic potential and consequent quality of the water from the Mumbuca stream, which supplies the city of Monte Carmelo, located in the Minas Triangle region, Minas Gerais, Brazil. This was achieved using two variable response bioindicators (Rhamdia quelen and Geophagus brasiliensis), the micronucleus (MN) test, and determining the presence of metals by flame atomic absorption spectrometry. Results showed that site 3 water (region of residential flow and intense industrial pottery activity) presented a greater possibility for induction of genotoxic activity, as evidenced by the increase in the MN frequency in Rhamdia quelen and Geophagus brasiliensis in comparison with the reference-site water. The water of the Mumbuca stream was influenced by genotoxic agents, especially lead and chromium, assessed by the rise in MN rate. Data suggested that discharge of industrial effluents in a specific stretch of the stream interfered with biota functions.

Standardization of bulb and root sample sizes for the Allium cepa test

Although the Allium cepa test has been widely used to identify potentially cytotoxic and genotoxic pollutants in aquatic environments, variable non-standardized choices have been made regarding the number of plant bulbs and roots analyzed. We propose numbers for bulbs and roots per bulb when comparing the frequencies of micronuclei, mitotic anomalies and mitotic index with this test. Roots that had been treated with aqueous solutions, such as water samples collected in August 2007 from the Paraíba do Sul River at the Brazilian cities of Tremembé and Aparecida; negative and positive controls were used for bioassays. The presence of pollutants in the river water had been presumed based on our previous cytological data and an official report by the São Paulo State Environmental Agency (Brazil) on presence of fecal contaminants (Tremembé and Aparecida) and elevated dissolved aluminium (Aparecida) in the water under study. The sampling of ten bulbs and five roots per bulb was found adequate for comparative studies to evaluate with the A. cepa test the potential damage inflicted by pollutants in aquatic environments. Furthermore, even one bulb and one root per bulb was sufficient in discerning this damage, thereby shortening the time required to attain a statistically confident comparative evaluation. However, to allow for the use of statistical programs based on the evaluation of average values, and to avoid criticism based on genetic variability, we propose that three bulbs and three roots per bulb be considered as standard sample sizes for the A. cepa test.

Hospital waste incinerator bottom ash leachate induced cyto-genotoxicity in Allium cepa and reproductive toxicity in mice

The potentials of hospital incinerator bottom ash leachate (HIBAL) to induce cyto-genotoxicity in Allium cepa and reproductive anomalies in the mouse were investigated. The leachate obtained from simulation of the bottom ash was analyzed for some physico-chemical parameters. The A. cepa, mouse sperm morphology and histopathological tests were carried out at concentrations ranging from 1% to 50% of the leachate sample. In A. cepa, HIBAL caused significant (p < 0.05) inhibition of root growth and induction of chromosomal aberrations. In the animal assays, there was 100% mortality at the 50% concentrations. The leachate caused insignificant (p > 0.05) concentration-dependent induction of various types of sperm morphology. There was accumulation of fluid in the seminiferous tubule lumen and necrosis of stem cells in the testes. These effects were believed to be provoked by the somatic and germ cell genotoxins, particularly the heavy metals in the leachate. Our finding is of environmental and public health significance.