Evaluation of the genotoxic, mutagenic and oxidant stress potentials of municipal solid waste incinerator bottom ash leachates

Health risk assessment of toxic metals and DNA damage in somatic and germ cells by soil and groundwater of a major cement factory in Nigeria

The waste generated from cement manufacturing is an important source of heavy metal contamination of groundwater and soil. This study investigated the concentration of toxic metals in the soil of a major cement factory and nearby groundwater. Ecological and carcinogenic risks of the metals were calculated. Potential reproductive toxicity and genotoxic effects of the samples were assessed in the sex and somatic cells of male mice using sperm abnormalities and bone marrow micronucleus (MN) assays, respectively. Also, the serum ALP, ALT, AST, total testosterone (TT), luteinizing hormone (LH), and follicle-stimulating hormone (FSH); and liver SOD and CAT activities were measured in the treated mice. Cr, Cu, Ni, Zn, Mn, Cd, and Pb levels in the soil and groundwater exceeded the allowable maximum standard. Ingestion and dermal contact were the most probable routes of human exposure with children having about 3 times higher probability of exposure to the metals than adults. Ni, Pb, and Cr presented carcinogenic risks in children and adults. In the MN result, nuclear abnormalities in the studied mice especially micronucleated polychromatic erythrocytes increased significantly (P < 0.05). Compared to the negative control, the ratio of PCE/NCE showed the cytotoxicity of the 2 samples. Data further showed a significant increase in the serum ALP, AST, and ALT while the liver CAT and SOD activities concomitantly decreased in the exposed mice. Sperm morphology results showed that the samples contained constituents capable of inducing reproductive toxicity in exposed organisms, with alterations to the concentrations of TT, LH, and FSH. Toxic metal constituents of the samples were believed to induce these reported reproductive toxicity and genotoxic effects. These results showed the environmental pollution caused by cement factories and the potential effects the pollutants might have on exposed eukaryotic organisms.

Health risk and germ cell toxicity of five commercially available sachet waters in Nigeria: a public health concern

Background

Sachet water is the most common form of portable water commercially available in Nigeria.

Methodology

Using the murine sperm count and sperm abnormality assay, the germ cell toxicity of five common commercially available sachet waters in Nigeria was assessed in this study. The levels of hormones such as Follicle Stimulating Hormone (FSH), Luteinizing Hormone (LH) and Total Testosterone (TT); and activities of catalase (CAT), alanine aminotransferase (ALT), superoxide dismutase (SOD), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) were evaluated. The heavy metal and physicochemical parameters of the sachet waters were also analyzed. Healthy male mice were allowed to freely drink the sachet waters for 35 days after which they were sacrificed.

Results

The findings indicated that the concentrations of some heavy metals (As, Cr, and Cd) in the sachet waters exceeded the limit by regulatory organizations. The data of the total carcinogenic risk (TCR) and total non-carcinogenic risk (THQ) of some heavy metals associated with the ingestion of sachet water for adults and children showed that the values exceeded the acceptable threshold, and thus, is indicative of a high non-carcinogenic and carcinogenic risks. The data of the sperm abnormality assay showed that in the exposed mice, the five sachet waters induced a statistically significant (P < 0.05) increase in abnormal sperm cells and a significantly lower mean sperm count. Additionally noted were changes in the serum activities of TT, FSH, ALP, AST, ALT, and LH.

Conclusion

Thus, the sachet waters studied contained agents that can induce reproductive toxicity in exposed humans. This is of public health importance and calls for immediate action by regulatory bodies.

Biomarker response index in earthworms following chronic exposure to leachate from a closed dumpsite: Behavioral, cytotoxicity and antioxidant system alterations

Leachate, an effluent produced during solid waste decomposition, interacts directly with soil, mainly in dumpsite areas. Studies on terrestrial animal exposure to leachate are, however, lacking. Plants are the most frequently studied organisms, while animal studies, especially earthworms, are limited. Nevertheless, ecotoxicological assessments involving earthworms are crucial due to their role in soil health and ecosystem maintenance, which are paramount in understanding potential terrestrial ecosystem leachate effects. In this context, this study aimed to evaluate behavioral effects, sublethal cytotoxicity and antioxidant system alterations in Eisenia andrei earthworms chronically exposed to leachate from a closed dumpsite. Cytotoxicity was determined by coelomocyte density, viability and cell typing, while antioxidant system alterations were assessed through superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST), reduced glutathione (GSH) and metallothionein (MT) determinations. Malondialdehyde (MDA) and protein carbonylation (PTC) levels were also determined as oxidative effect markers. Finally, the Biomarker Response Index (BRI) was assessed, aiming to quantitatively integrate the results of the investigated endpoints and establish a biological health state (BHS) for each leachate concentration. Leachate exposure led to leak responses at concentrations of up to 50%, but attraction at higher concentrations. Decreased cell density (28%) was observed after 48 days and reduced viability (50%), after 14 days of leachate exposure. The observed cell typing changes indicate anti-inflammatory immune system effects. Leachate exposure led to several antioxidant system alterations, increasing SOD (2-6 %), CAT (5-35 %) and GST (5-70 %) activities and GSH (7-37%) and MT (3-67%) levels. Earthworm antioxidant defenses were, however, able to prevent lipid peroxidation, which decreased (11-37%) following leachate exposure to concentrations above 12.5%, and PTC, which increased at 42 days (26%) and reduced at 56 days (12 %). This is the first PTC assessment in leachate-exposed earthworms. The increased carbonylation levels observed after 42 days alongside MDA decreases highlight the need for further research employing oxidative effect biomarkers other than MDA. Finally, an integrated approach employing the BRI was carried out, revealing mild initial changes evolving to moderate to major effects at the highest leachate exposure concentration, with an effect attenuation detected at the end of the experiment. In this sense, this study brings forth a significant novelty, employing a biomarker previously not assessed in earthworms, demonstrating an oxidative effect, alongside the use of the BRI as an integrative tool for the endpoints applied in this assessment.

Mitochondrial dysfunctions elicited by solid waste leachates provide insights into mechanisms of leachates induced cell death and pathophysiological disorders

Emissions (mainly leachates and landfill gases) from solid waste facilities are laden with mixtures of dangerous xenobiotics implicated with significant increase in various pathophysiological disorders including cancer, and eventual mortality of exposed wildlife and humans. However, the molecular mechanisms of solid waste leachates induce pathophysiological disorders and cell death are still largely unknown. Although, evolving evidence implicated generation of reactive oxygen species and oxidative stress as the possible mechanism. Recent scientific reports are linking reactive oxygen species and mitochondrial dysfunctions as the player mechanism in pathophysiological disorder and apoptosis induced by xenobiotics in solid waste leachates. This systematic review presents an explicit discussion of recent scientific findings on the structural and functional alterations in mitochondria induced by solid waste leachates as the molecular mechanisms plausibly responsible for the pathophysiological disorders, cancer and cell death reported in landfill toxicology and epidemiological studies. This review aims to increase scientific understanding on solid waste leachate induced mitochondria dysfunctions as the key player in molecular mechanisms of solid waste induced toxicity. The findings in this review were mainly from using primary cells, cell lines, Drosophila and fish. Whether the findings will similarly be observed in mammalian test systems in vivo and particularly in exposed humans, remained to be investigated. Improvement in technological advancements, enforcement of legislation and regulations, and creation of sophisticated health surveillance against exposure to solid waste leachates, will expectedly mitigate human exposure to solid waste emissions and contamination of the environment.

Comparative study of the reproductive toxicity and modulation of enzyme activities by crude oil-contaminated soil before and after bioremediation

Contamination of soil with crude oil is a serious ecological problem with potential adverse public health effects. This study assessed the germ cell toxicity of simulated leachates from crude oil-contaminated soil before and after bioremediation using the murine sperm abnormality assay, sperm count, and testes histopathology. The levels of Total Testosterone (TT), Follicle Stimulating Hormone (FSH), and Luteinizing Hormone (LH); and activities of catalase (CAT), alkaline phosphatase (ALP), superoxide dismutase (SOD), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) were determined. The physicochemical, Total Petroleum Hydrocarbon (TPH), and heavy metal analyses of the leachates were also carried out. Male mice were exposed to 50, 25, 10, 5, and 1% (v/v; leachate:distilled water) of the leachate samples for five consecutive days, and were sacrificed after 35 days. The result showed a statistically significant (p < 0.05), concentration-dependent increase in abnormal sperm cells in exposed mice, with aberrations such as folded sperm, amorphous head, wrong tail attachment, distal droplet, no hook, and looped tail. Data further showed a concentration-dependent significant reduction in mean sperm count in the exposed mice. Alterations of seminiferous tubules with different lesions and activities of ALT, AST, ALP, FSH, LH, and TT were also recorded. The high level of selected heavy metals (As, Cr, Cd, Cu, and Pb) and TPH was believed to contribute to the observed reproductive toxicity and modulated enzyme activities in the treated mice. It is therefore concluded that the microbial remediation of the crude oil contaminated soil produced a reduction in the levels of heavy metals and TPH in the soil, reduced reproductive toxicity, and modulation of enzyme activities. However, the induced reproductive toxicity by the bioremediated soil is still significant, hence, further work could be done to employ a consortium of bacteria and extend the period of the bioremediation process to ensure complete removal of the contaminants.

Long-term landfill leachate exposure modulates antioxidant responses and causes cyto-genotoxic effects in Eisenia andrei earthworms

It is estimated that approximately 0.4% of the total leachate produced in a landfill is destined for treatment plants, while the rest can reach the soil and groundwater. In this context, this study aimed to perform leachate toxicity evaluations through immune system cytotoxic assessments, genotoxic (comet assay) appraisals and antioxidant system (superoxide dismutase - SOD; catalase - CAT, glutathione-S-transferase - GST; reduced glutathione - GSH and metallothionein - MT) evaluations in Eisenia andrei earthworms exposed to a Brazilian leachate for 77 days. The leachate sample contained high organic matter (COD - 10,630 mg L^-1) and ammoniacal nitrogen (2398 mg L^-1), as well as several metals, including Ca, Cr, Fe, Mg, Ni and Zn. Leachate exposure resulted in SOD activity alterations and increased CAT activity and MT levels. Decreased GST activity and GSH levels were also observed. Antioxidant system alterations due to leachate exposure led to increased malondialdehyde levels as a result of lipid peroxidation after the 77 day-exposure. An inflammatory process was also observed in exposed earthworms, evidenced by increased amoebocyte density, and DNA damage was also noted. This study demonstrates for the first time that sublethal effect assessments in leachate-exposed earthworms comprise an important tool for solid waste management.

Characterization of leachates from waste landfill sites in a religious camp along Lagos-Ibadan expressway, Nigeria and its hepatotoxicity in rats

Landfill sites near human settlements are known to have adverse health effects. Here, we investigated the effect of different concentrations of leachates from the Redemption Camp landfill (RCLL, 10%, 30%, 50%) on the liver of adult female rats after 21 days of exposure in their drinking water. The physicochemical and metal analyses showed that biochemical oxygen and chemical oxygen demand, zinc and magnesium levels were significantly high, whereas copper level was low in RCLL when compared to water samples from residential areas close to the landfill site, and were higher than the acceptable limits (p < 0.05). The predominant bacteria isolates recovered from the leachate and drinking water samples were Escherichia coli, Salmonella spp and Shigella spp. At the end of the 21-day exposure, RCLL increased the weight of the liver. Malondialdehyde concentrations were increased and glutathione levels were decreased significantly in the liver of treated animals at all concentrations of leachates tested. Furthermore, the activities of serum alanine amino transferase, aspartate amino transferase, gamma glutamyl transferase and cholesterol concentrations were increased whereas bilirubin and albumin levels were decreased dose-dependently. Histological examination of the liver was characterized by accumulation of inflammatory cells around hepatocytes, and extended sinusoids. The histo-pathological alterations and oxidative damage observed in the liver of treated rats and occurrence of pathogenic species and metals in the RCLL may suggest possible impaired hepatic health in subjects with occupational or environmental exposure.

Response of Zea mays to multimetal contaminated soils: a multibiomarker approach

Heavy metals present in mine tailings pollute agroecosystems, put the integrity of the environment at risk and become a major route of exposure to humans. The present study was carried out in Taxco, Guerrero, Mexico, where millions of tons of mine tailings have been deposited. Soils from this region are used for agricultural activities. Maize (Zea mays) was selected as a test plant, because it is one of the most common and important cereal crops in Mexico and worldwide. Thirteen metals were selected and their bioaccumulation in roots, leaves and fruits were measured in plants cultivated in soils contaminated with mine tailings and those cultivated in non-contaminated soils. The effect of metal bioaccumulation on: macro and micromorphology, size, biomass, coloration leaf patterns and on DNA damage levels in different structures were determined. The bioaccumulation pattern was: root > leaf > fruit, being only Mn and Cr bioaccumulated in all three structures and V in the roots and leaves. A significant effect of metal bioaccumulation on 50% of the size and leaf shape and 55% of the biomass characters in Z. mays exposed plants was detected. Regarding micromorphological characters, a significant effect of metal bioaccumulation on 67% of the leaf characters and on 100% of the color basal leaf characters was noted. The effect of metal bioaccumulation on the induction of DNA damage (leaf > fruit > root) was detected employing single cell gel electrophoresis analysis. An approach, in which multi endpoints are used is necessary to estimate the extent of the detrimental effects of metal pollution on agroecosystem integrity contaminated with mine tailings.

Antioxidant biomarkers in Gammarus pulex to evaluate the efficiency of electrocoagulation process in landfill leachate treatment

The discharge of landfill leachate into the environment without effective treatment poses a serious threat for the aquatic ecosystems. This present study was undertaken to evaluate whether electrocoagulation process is efficient for treatment landfill leachate (LL) or not by using antioxidant biomarkers in Gammarus pulex. Glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), and catalase (CAT) activities and malondialdehyde (MDA) and glutathione (GSH) levels in G. pulex exposed to untreated, treated, and diluted rates 1/10 and 1/20 in both LL during 24 and 96 h were tested. Physiochemical characteristics of leachate (chemical oxygen demand, electrical conductivity, pH, phosphate, turbidity, NH₃, Cl^-, and color) were determined pre and post treatment. All physiochemical characteristics of LL decreased after treatment process. GSH-Px and CAT activities and GSH and MDA levels were increased in untreated groups when compared to control (p < 0.05). After treatment by electrocoagulation, MDA and GSH levels and CAT activities were returned to control values. In conclusion, the abilities of LL to stimulate oxidative stress in G. pulex have been proven. The results revealed that antioxidant parameters are useful biomarkers for determining the treatment efficiency of the electrocoagulation process.

Phytotoxicity and groundwater impacts of leaching from thermal treatment residues in roadways

The use of coal fly ash (CFA), municipal solid waste incinerator bottom ash (MSWIBA) and flue gas desulfurization residue (FGDR) in road construction has become very common owing to its economical advantages. However, these residues may contain toxic constituents that pose an environmental risk if they leach out and flow through the soil, surface water and groundwater. Therefore, it is necessary to assess the ecotoxicity and groundwater impact of these residues before decisions can be made regarding their utilization for road construction. In this study, the physico-chemical characteristics, leaching and phytotoxicity of these residues were investigated. Specifically, multivariate analyses were used to evaluate the contributions of the leaching constituents of the CFA, MSWIBA and FGDR leachates to the germination index of wheat seeds. B, Ba, Cr, Cu, Fe and Pb were found to be more toxic to the wheat seeds than the other heavy metals. Furthermore, the leached concentrations of the constituents from the CFA, MSWIBA and FGDR were below the regulatory threshold limits of the Chinese identification standard for hazardous wastes. Analyses conducted using a numerical groundwater model (WiscLEACH) indicated that the predicted field concentrations of metals from the CFA, MSWIBA and FGDR increased with time up to about 30years at the point of compliance, then decreased with time and distance. Overall, this study demonstrated that the risks resulting from MSWIBA, CFA and FGDR leaching could be assessed before its utilization for road construction, providing crucial information for the adoption of these alternative materials.

Genetic damage induced by electronic waste leachates and contaminated underground water in two prokaryotic systems

The inappropriate and unsafe management practices related to disposal and recycling of electronic wastes in Nigeria has led to environmental and underground water contamination. Reports on the level and type of contamination as well as the possible DNA damage effects of this contamination are insufficient. This study evaluated the DNA damaging potential of e-waste simulated and raw leachates, and its contaminated underground water using the SOS chromotest on Escherichia coli PQ37 and the Ames Salmonella fluctuation test on Salmonella typhimurium strains TA98 and TA100, without and with metabolic activation. Physico-chemical parameters of the samples were also analyzed. The result of the Ames test showed induction of base pair substitution and frameshift mutation by the test samples. However, the TA100 was the more responsive strain for the three samples in terms of mutagenic index in the absence and presence of metabolic activation. The SOS chromotest results were in agreement with those of the Ames Salmonella fluctuation test. Nevertheless, the E. coli PQ37 system was slightly more sensitive than the Salmonella assay for detecting genotoxins in the tested samples. Lead, cadmium, manganese, copper, nickel, chromium, arsenic, and zinc contents analyzed in the samples were believed to play a significant role in the observed DNA damage in the microbial assays. The results of this study showed that e-waste simulated and raw leachates, and its contaminated underground water are of potential mutagenic and genotoxic risks to the exposed human populace.

Occupational exposure to Mount Etna's basaltic dust: Assessment of mutagenic and cytotoxic effects

Basalt and volcanic ash are natural constituents of the ground surrounding volcanic areas such as Mount Etna. The dust may be daily inhaled by the general population as well as by several types of workers, such as construction workers. In this experiment, we analyzed the potential mutagenic and cytotoxic effects of the materials used in construction industry, excavated from Mt. Etna. Ground basalt (A), volcanic ash (B), mixed basalt and cement (C) and cement (D) were studied with Ames test, for mutagenic assessment and with MMT assay for cytotoxic evaluation. The Ames test revealed that cement (sample D), showed a higher and significant mutagenicity than the samples A, B and C. MTT assay showed that samples C and D had a slightly more negative impact on cell viability than A and B. In conclusion, no particular risks seem to exist for construction industry workers, while the exploitation of cement and cement mixed with basalt seems to be a risk for workers, given the high percentage of silica and iron.

In vivo micronucleus test in the assessment of cytogenotoxicity of landfill leachates in three animal models from various ecological habitats

The in vivo micronucleus (MN) test, a standard test for the genotoxicity screening of xenobiotics, was used to evaluate the cytotoxic and genotoxic activities of landfill leachates in Clarias gariepinus, Coturnix coturnix japonica and Rattus norvegicus. These organisms were exposed to various sub-lethal concentrations (1-50%) of Olusosun and Aba Eku landfill leachates. At post exposure, peripheral erythrocytes from catfish and quail, and bone marrow cells of quail and rat were subjected to MN analysis following standard protocols. The leachates induced significant increase in MN formation and total nuclear abnormalities (NAs) in the peripheral erythrocytes of catfish and quail. NAs occurred in the order; BN > BL > LB > NT in the catfish and BN > BudN > TLN > TN in quail. There was significant increase in MN formation in the bone marrow cells of quail, and micronucleated polychromatic erythrocytes and micronucleated normochromatic erythrocytes formation in the bone marrow of rats. The concentration dependent significant (p < 0.05) decrease in the PCE/NCE ratio in the bone marrow of the leachate treated rats suggest alterations in the bone marrow cell proliferation, leading to the suppression of immature erythrocytes (PCE). MN induction showed positive corrections with leachate concentrations in the test organisms; and it increased with exposure duration in the catfish. Indiscriminate disposal of solid waste generates leachates containing multiple xenobiotics that are capable of increasing genomic instability among vertebrates inhabiting various ecological habitats.

Variation of the phytotoxicity of municipal solid waste incinerator bottom ash on wheat (Triticum aestivum L.) seed germination with leaching conditions

Municipal solid waste incinerator bottom ash (MSWIBA) has long been regarded as an alternative building material in the construction industry. However, the pollutants contained in the bottom ash could potentially leach out and contaminate the local environment, which presents an obstacle to the reuse of the materials. To evaluate the environmental feasibility of using MSWIBA as a recycled material in construction, the leaching derived ecotoxicity was assessed. The leaching behavior of MSWIBA under various conditions, including the extractant type, leaching time, liquid-to-solid (L/S) ratio, and leachate pH were investigated, and the phytotoxicity of these leachates on wheat (Triticum aestivum L.) seed germination was determined. Moreover, the correlation between the germination index and the concentrations of various chemical constituents in the MSWIBA leachates was assessed using multivariate statistics with principal component analysis and Pearson's correlation analysis. It was found that, heavy metal concentrations in the leachate were pH and L/S ratio dependent, but were less affected by leaching time. Heavy metals were the main pollutants present in wheat seeds. Heavy metals (especially Ba, Cr, Cu and Pb) had a substantial inhibitory effect on wheat seed germination and root elongation. To safely use MSWIBA in construction, the potential risk and ecotoxicity of leached materials must be addressed.

Vicia faba bioassay for environmental toxicity monitoring: A review

Higher plants are recognized as excellent genetic models to detect cytogenetic and mutagenic agents and are frequently used in environmental monitoring studies. Vicia faba (V. faba) bioassay have been used to study DNA damages i.e., chromosomal and nuclear aberrations induced by metallic compounds, pesticides, complex mixtures, petroleum derivates, toxins, nanoparticles and industrial effluents. The main advantages of using V. faba is its availability round the year, economical to use, easy to grow and handle; its use does not require sterile conditions, rate of cell division is fast, chromosomes are easy to score, less expensive and more sensitive as compared to other short-term tests that require pre-preparations. The V. faba test offers evaluation of different endpoints and tested agents can be classified as cytotoxic/genotoxic/mutagenic. This test also provides understanding about mechanism of action, whether the tested agent is clastogenic or aneugenic in nature. In view of advantages offered by V. faba test system, it is used extensively to assess toxic agents and has been emerged as an important bioassay for ecotoxicological studies. Based on the applications of V. faba test to assess the environmental quality, this article offers an overview of this test system and its efficiency in assessing the cytogenetic and mutagenic agents in different classes of the environmental concerns.

The genotoxicity and systemic toxicity of a pharmaceutical effluent in Wistar rats may involve oxidative stress induction

There is scarcity of information on the possible mechanisms of pharmaceutical effluent induced genotoxicity and systemic toxicity. This study investigated the genotoxicity and systemic toxicity of a pharmaceutical effluent in Wistar rats. Rats were orally treated with 5-50% concentrations of the effluent for 28 days. At post-exposure, blood, liver, kidney and bone marrow cells were examined for alterations in serum biochemical parameters and hematological indices, histopathological lesions and micronucleated polychromatic erythrocytes formation (MNPCE). The effluent caused concentration independent significant (p < 0.05) alterations in aspartate (AST) and alanine (ALT) aminotransferases, superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), total and direct bilirubin and creatinine. There was reduction in red blood count (RBC), hemoglobin concentration (HGB), platelets, percentage hematocrit (HCT), white blood count (WBC) and mean corpuscle hemoglobin (MCH) except mean corpuscle hemoglobin concentration (MCHC), which increased in the treated rats. Histopathological lesions observed in the liver and kidney of the effluent treated rats were thinning of the hepatic cord, kuffer cell hyperplasia, vacuolation of the hepatocytes and renal cells, multifocal inflammatory changes, necrosis and congestion of the renal blood vessels and central vein. MNPCE significantly increase in the bone marrow of the treated rats compared to the negative control. The concentration of some toxic metals and anions in the effluent were above standard permissible limits. These findings showed that the pharmaceutical effluent caused somatic DNA damage and systemic toxicity in rats may involve induction of oxidative stress, suggesting environmental contamination and health risks in wildlife and humans.

Evaluating the mutagenicity of leachates obtained from the bottom ash of a municipal solid waste incinerator by using a Salmonella reverse mutation assay

The mutagenic potential of leachates derived from the bottom ash of a municipal solid waste incinerator in Taiwan were evaluated using an Ames Salmonella mutagenicity assay with three standard tester strains, TA98, TA100, and TA1535. Three types of leachants, leachant A (pH 4.93), leachant B (pH 2.88), and leachant C (deionized water, pH 6.0), were carried out according to toxicity characteristic leaching procedure (TCLP). Moreover, two types of bottom ash, nonsieved and sieved bottom ash (particle size <4.75 mm), were analyzed with the TCLP and the Ames assay. The concentrations of five heavy metals (Cd, Cr, Cu, Pb, and Zn) in the leachates were also estimated with an ICP-OES. The results indicated that the metal concentrations in the TCLP leachates of bottom ash were all below the limits set by Taiwanese regulations. However, leachate A from nonsieved and <4.75-mm-sieved bottom ash showed mutagenicity. Moreover, leachate A from <4.75 mm-sieved bottom ash displayed stronger mutagenicity than that from nonsieved ash. The leachate A from <4.75-mm-sieved bottom ash, that were diluted by 100-fold showed no mutagenicity. In conclusion, our results suggested that the chemical composition and mutagenic potential of leachates should be monitored to evaluate the safety of bottom ash.

Soil genotoxicity assessment--results of an interlaboratory study on the Vicia micronucleus assay in the context of ISO standardization

The Vicia micronucleus assay was standardized in an international protocol, ISO 29200, "Assessment of genotoxic effects on higher plants-Vicia faba micronucleus test," for soil or soil materials (e.g., compost, sludge, sediment, waste, and fertilizing materials). The aim of this interlaboratory study on the Vicia micronucleus assay was to investigate the robustness of this in vivo assay in terms of its applicability in different countries where each participant were asked to use their own seeds and reference soil, in agreement with the ISO 29200 standard. The ISO 29200 standard protocol was adopted for this study, and seven laboratories from three countries (France, Italy, and Brazil) participated in the study. Negative and positive controls were correctly evaluated by 100 % of the participants. In the solid-phase test, the micronucleus frequency (number of micronuclei/1,000 cells) varied from 0.0 to 1.8 for the negative control (i.e., Hoagland's solution) and from 5.8 to 85.7 for the positive control (i.e., maleic hydrazide), while these values varied from 0.0 to 1.7 for the negative control and from 14.3 to 97.7 for the positive control in the case of liquid-phase test. The variability in the data obtained does not adversely affect the robustness of the protocol assessed, on the condition that the methodology described in the standard ISO 29200 is strictly respected. Thus, the Vicia micronucleus test (ISO 29200) is appropriate for complementing prokaryotic or in vitro tests cited in legislation related to risk assessment of genotoxicity potential.

Mitigation mechanism of Cd-contaminated soils by different levels of exogenous low-molecular-weight organic acids and Phytolacca americana

Phytolacca americana L. (pokeweed) is a promising plant for phytoremediation of cadmium (Cd)-contaminated soil, with its large biomass and fast growth rate.

Toxicity of sulcotrione and grape marc on Vicia faba cells

The cell toxicity of sulcotrione, a selective triketone herbicide, was evaluated on Vicia faba. Sulcotrione, trademark Mikado, grape marc, and mixtures of sulcotrione or Mikado with grape marc induced cell death. Addition of grape marc to either sulcotrione or Mikado enhanced cell death, especially with Mikado. Addition of grape marc to herbicides, sulcotrione, or Mikado resulted in different expression of genes usually associated with cell stress. Mixtures of grape marc and herbicides enhanced transcript accumulation for ubiquitin, hsp 70, and cytosolic superoxide dismutase, but did not change ascorbate peroxidase transcript accumulation. The results thus provide evidence that sulcotrione, Mikado, and mixtures with grape marc can trigger cell death and specific gene expressions. Cocktails of products with sulcotrione, such as commercial additives and grape marc, can modify biological features of pesticide. Moreover, grape marc differently enhanced cell toxicity of sulcotrione and Mikado, suggesting a synergy between pesticide products and grape marc.

Pb-inhibited mitotic activity in onion roots involves DNA damage and disruption of oxidative metabolism

Plant responses to abiotic stress significantly affect the development of cells, tissues and organs. However, no studies correlating Pb-induced mitotic inhibition and DNA damage and the alterations in redox homeostasis during root division per se were found in the literature. Therefore, an experiment was conducted to evaluate the impact of Pb on mitotic activity and the associated changes in the oxidative metabolism in onion roots. The cytotoxic effect of Pb on cell division was assessed in the root meristems of Allium cepa (onion). The mitotic index (MI) was calculated and chromosomal abnormalities were sought. Pb-treatment induced a dose-dependent decrease in MI in the onion root tips and caused mitotic abnormalities such as distorted metaphase, fragments, sticky chromosomes, laggards, vagrant chromosomes and bridges. Single Cell Gel Electrophoresis was also performed to evaluate Pb induced genotoxicity. It was accompanied by altered oxidative metabolism in the onion root tips suggesting the interference of Pb with the redox homeostasis during cell division. There was a higher accumulation of malondialdehyde, conjugated dienes and hydrogen peroxide, and a significant increase in the activities of superoxide dismutases, ascorbate peroxidases, guaiacol peroxidases and glutathione reductases in Pb-treated onion roots, whereas catalases activity exhibited a decreasing pattern upon Pb exposure. The study concludes that Pb-induced cytotoxicity and genotoxicity in the onion roots is mediated through ROS and is also tightly linked to the cell cycle. The exposure to higher concentrations arrested cell cycle leading to cell death, whereas different repair responses are generated at lower concentrations, thereby allowing the cell to complete the cell cycle.

Electronic waste leachate-mediated DNA fragmentation and cell death by apoptosis in mouse fibroblast (NIH/3T3) cell line

This study investigated the apoptotic effect of electronic waste on fibroblast cell line. Cells were treated with different concentrations of the leachate for 24h. Cell viability was detected by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) test, nuclear morphology of cells was explored by acridine orange (AO)/ethidium bromide (EB) double staining, mitochondrial membrane potential was evaluated using JC-1 probe while cell cycle analysis was conducted using flow cytometry. The oxidative status was detected using DCFH-DA (dichlorofluorescin diacetate) probe and the relationship between cell death and ROS (reactive oxygen species) was investigated using N-acetylcysteine. Results showed an increased cell death as detected by MTT assay and AO/EB staining. Cell cycle analysis indicated an induction of sub/G1 events while JC-1 probe showed significant disruption of mitochondrial membrane potential. There was significant induction of ROS, while N-acetylcysteine protected the cells from DNA damage. These suggest apoptotic pathway as a possible mechanism of e-waste induced cyto-genotoxicity.

Determination of the mutagenic and genotoxic potential of simulated leachate from an automobile workshop soil on eukaryotic system

Contamination of soil and water bodies with spent engine oil and petroleum products is a serious ecological problem, primarily in the automobile workshops and garages. This has potential short and chronic adverse health risks. Information is currently scarce on the potential mutagenicity and genotoxicity of such wastes. In this study, the potential mutagenic and genotoxic effects of simulated leachate from automobile workshop soil in Sagamu, Ogun state, Nigeria, were investigated. The assays utilized were bone marrow micronucleus (MN) and chromosome aberration (CA), sperm morphology and sperm count in mice. The physicochemical analysis of the leachate was also carried out. Experiments were carried out at concentrations of 1, 5, 10, 25, 50, 75 and 100% (volume per volume; leachate:distilled water) of the leachate sample. MN analysis showed a concentration-dependent induction of micronucleated polychromatic erythrocytes across the treatment groups. In the CA test, there was concentration-dependent significant reduction in mitotic index and induction of different types of CAs. Assessment of sperm shape showed a significant increase in sperm abnormalities with significant decrease in mean sperm count in treated groups. Heavy metals analyzed in the tested sample are believed to contribute significantly to the observed genetic damage. This indicates that automobile workshop soil-simulated leachate contains potential genotoxic agents and constitutes a genetic risk in exposed human population.

Improvement of Vicia-micronucleus test for assessment of soil quality: a proposal for international standardization

The Viciafaba root tip micronucleus test is one of the most employed plant genotoxicity assays, and has been used on various types of contaminated materials. This test has been standardized by AFNOR, the French member organization of ISO. However, this test is usually performed with a water extraction step but soil genotoxicity assessment would be more relevant when performed directly in the soil itself. In order to harmonize these protocols, an ISO standard for the V.faba micronucleus test in both liquid phase (exposure of plants to different liquid matrix, including soil water extracts) and solid phase (direct exposure of plants to the soil) would be very useful. In this context, we compared two exposure durations in the solid phase (48 h and 5 d) for the V.faba micronucleus test with two different well-known genotoxicants, maleic hydrazide and copper sulfate. We concluded that these two durations induced equivalent sensitivity: the micronucleus frequency was significantly increased with 5 μmol maleic hydrazide per kg dry soil and with 2 mmol copper sulfate per kg dry soil with both exposure durations. However, exposing roots to soil during 48 h is more practical. Moreover, organically and conventionally cultured seeds were employed to determine whether the seed provenance influenced the test sensitivity. Organic seeds were less sensitive to copper, possibly because copper-based treatments are permitted, and often applied, in organic farms. Therefore, in the absence of completely non-treated seeds, organically-cultured seeds did not appear to offer any advantages over conventional seeds.

DNA and oxidative damage induced in somatic organs and tissues of mouse by municipal sludge leachate

Pollution by waste landfill leachate has prompted a number of studies on the toxic and potential health effects. This study assessed the genotoxicity of a municipal sludge leachate (MSL) in the somatic tissues (blood and bone marrow) and organs (liver, kidney, and spleen) of mice using the alkaline Comet assay. The possible cause of DNA damage via the study of antioxidant system (lipid peroxidation [LPO]; catalase [CAT]; reduced glutathione [GSH]; and superoxide dismutase [SOD]) responses in mouse liver was also investigated. Different concentrations (2.5%, 5%, 10%, and 15%) of the leachate were administered intraperitoneally for 5 consecutive days to male Swiss albino mice (4 mice/group). A significant (p < 0.05) increase in DNA damage in organs and tissues of treated mice compared to the negative control was observed as evident from the Comet assay parameters: olive tail moment (OTM, arbitrary units) and tail DNA (%). Bone marrow showed maximum DNA damage followed by liver > spleen > kidney > blood as evident by the OTM. A significant increase (p < 0.05) in the level of antioxidant enzymes (CAT and SOD) and LPO with a concurrent decrease in GSH in the liver of treated mice was also observed. Our finding demonstrates that the MSL induces DNA damage in the somatic tissues and organs of mouse as well as induces oxidative stress in the liver. These tissues and organs may be the potential targets in animal and human populations exposed to MSL. This is of relevance to public health; as such exposure could lead to adverse health effects via systemic genotoxicity.

Environmental impact of sunscreen nanomaterials: ecotoxicity and genotoxicity of altered TiO2 nanocomposites on Vicia faba

Mineral sunscreen nanocomposites, based on a nano-TiO(2) core, coated with aluminium hydroxide and dimethicone films, were submitted to an artificial ageing process. The resulting Altered TiO(2) Nanocomposites (ATN) were then tested in the liquid phase on the plant model Vicia faba, which was exposed 48 h to three nominal concentrations: 5, 25 and 50 mg ATN/L. Plant growth, photosystem II maximum quantum yield, genotoxicity (micronucleus test) and phytochelatins levels showed no change compared to controls. Oxidative stress biomarkers remained unchanged in shoots while in roots, glutathione reductase activity decreased at 50 mg ATN/L and ascorbate peroxidase activity decreased for 5 and 25 mg ATN/L. Nevertheless, despite the weak response of biological endpoints, ICP-MS measurements revealed high Ti and Al concentrations in roots, and X-ray fluorescence micro-spectroscopy revealed titanium internalization in superficial root tissues. Eventual long-term effects on plants may occur.

Municipal landfill leachate induces hepatotoxicity and oxidative stress in rats

Human beings are more often exposed to complex mixtures of hazardous chemicals than single toxicant. The present study investigated the effects of Olushosun municipal landfill leachate (OMLL) from Ojota in Lagos State of Nigeria on hepatic function and some biomarkers of oxidative stress in adult rats. Physicochemical characteristic analysis of OMLL showed that while total alkalinity, total acidity, total hardness, biochemical oxygen demand and chemical oxygen demand were 3-fold, 2-fold, 4-fold and 1-fold, respectively, concentrations of heavy metals analysis showed that copper, lead, cadmium, arsenic, cobalt, chromium and mercury were 9-fold, 4-fold, 21-fold, 1320-fold, 7-fold, 5-fold and 4-fold, respectively, higher than acceptable limits by regulatory authorities. The OMLL was administered at 0, 10, 20, 30 and 40% concentrations to adult male rats for 14 days. Following exposure, serum was collected for serum biochemistry assays and liver was collected to determine the antioxidant status. Exposure of animals to 10, 20, 30 and 40% OMLL resulted in 3%, 31%, 52% and 83% increase in aspartate aminotransferase activity, whereas it elevated alanine aminotransferase activity by 10%, 25%, 30% and 49%, respectively, when compared with the control. While OMLL administration significantly increased catalase activity, a sequential decrease in reduced glutathione level and in superoxide dismutase and glutathione- S-transferase activities with concomitant increase in malondialdehyde level were observed, when compared with the control. Collectively, the hepatotoxicity of OMLL could be due to the induction of oxidative stress and may suggest possible health hazards in subjects with occupational or environmental exposure.

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.

Bioassays for evaluating the water-extractable genotoxic and toxic potential of soils polluted by metal smelters

Physicochemical analyses of polluted soils are limited in their ability to determine all hazardous compounds, their bioavailability, and their combined effects on living organisms. Bioassays, on the other hand, can evaluate environmental quality more accurately. This study assesses the genotoxic potential of water extracts from soil polluted with metals (Pb, Cd, and Zn) by the former lead smelter in zerjav, Slovenia using comet assay with Tetrahymena thermophila and human hepatoma cells (HepG2). In addition, the toxicity of soil samples and their extracts was evaluated using Vibrio fischeri and delayed fluorescence of Lemna minor. Chemical analyses of metals using atomic absorption spectrophotometry (AAS) was performed for comparison. Measurements of the total metal concentrations showed that four of five plots near the former lead smelter were highly contaminated with Pb, Cd, and Zn, but the amount of metals in water/soil extracts was low at all the sampling plots. Genotoxicity was demonstrated using T. thermophila for the majority of the extracts, and HepG2 cells for only some of the extracts. Whereas V. fischeri indicated a gradual decrease in soil toxicity with greater distance from the smelter, the toxicity of extracts did not correlate with proximity. Low concentrations of metals in water extracts stimulated L. minor growth. The results indicate that comet assay with T. thermophila and HepG2 cells and the BSPT with V. fischeri are suitable protocols for screening the genotoxic and toxic potential of water/soil extracts by comet assay, whereas chemical analyses of total metal concentrations in soil do not solely suffice for evaluating metal pollution in the environment. Biological assays are thus crucial for risk assessment.

Genotoxicity assessment of a pharmaceutical effluent using four bioassays

Pharmaceutical industries are among the major contributors to industrial waste. Their effluents when wrongly handled and disposed of endanger both human and environmental health. In this study, we investigated the potential genotoxicity of a pharmaceutical effluent, by using the Allium cepa, mouse- sperm morphology, bone marrow chromosome aberration (CA) and micronucleus (MN) assays. Some of the physico-chemical properties of the effluent were also determined. The A. cepa and the animal assays were respectively carried out at concentrations of 0.5, 1, 2.5, 5 and 10%; and 1, 5, 10, 25 and 50% of the effluent. There was a statistically different (p < 0.05), concentration-dependent inhibition of onion root growth and mitotic index, and induction of chromosomal aberrations in the onion and mouse CA test. Assessment of sperm shape showed that the fraction of the sperm that was abnormal in shape was significantly (p < 0.05) greater than the negative control value. MN analysis showed a dose-dependent induction of micronucleated polychromatic erythrocytes across the treatment groups. These observations were provoked by the toxic and genotoxic constituents present in test samples. The tested pharmaceutical effluent is a potentially genotoxic agent and germ cell mutagen, and may induce adverse health effects in exposed individuals.

Mutagenicity and genotoxicity of coal fly ash water leachate

Fly ash is a by-product of coal-fired electricity generation plants. The prevalent practice of disposal is as slurry of ash and water to storage or ash ponds located near power stations. This has lain to waste thousands of hectares of land all over the world. Since leaching is often the cause of off-site contamination and pathway of introduction into the human environment, a study on the genotoxic effects of fly ash leachate is essential. Leachate prepared from the fly ash sample was analyzed for metal content, and tested for mutagenicity and genotoxicity. Analyses of metals show predominance of the metals-sodium, silicon, potassium, calcium, magnesium, iron, manganese, zinc, and sulphate. The Ames Salmonella mutagenicity assay, a short-term bacterial reverse mutation assay, was conducted on two-tester strains of Salmonella typhimurium strains TA97a and TA102. For genotoxicity, the alkaline version of comet assay on fly ash leachate was carried in vitro on human blood cells and in vivo on Nicotiana plants. The leachate was directly mutagenic and induced significant (P<0.05) concentration-dependent increases in DNA damage in whole blood cells, lymphocytes, and in Nicotiana plants. The comet parameters show increases in tail DNA percentage (%), tail length (mum), and olive tail moment (arbitrary units). Our results indicate that leachate from fly ash dumpsites has the genotoxic potential and may lead to adverse effects on vegetation and on the health of exposed human populations.

Toxic reactivity of wheat (Triticum aestivum) plants to herbicide isoproturon

The herbicide isoproturon is widely used for controlling weed/grass in agricultural practice. However, the side effect of isoproturon as contaminants on crops is unknown. In this study, we investigated isoproturon-induced oxidative stress in wheat ( Triticum aestivum). The plants were grown in soils with isoproturon at 0-20 mg/kg and showed negative biological responses. The growth of wheat seedlings with isoproturon was inhibited. Chlorophyll content significantly decreased at the low concentration of isoproturon (2 mg/kg), suggesting that chlorophyll was rather sensitive to isoproturon exposure. The level of thiobarbituric acid reactive substances (TBARS), an indicator of cellular peroxidation, showed an increase, indicating oxidative damage to plants. The isoproturon-induced oxidative stress resulted in a substantial change in activities of the majority of antioxidant enzymes, including superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX). Activities of the antioxidant enzymes showed a general increase at low isoproturon concentrations and a decrease at high isoproturon concentrations. Activities of CAT in leaves showed progressive suppression under the isoproturon exposure. Analysis of nondenaturing polyacrylamide gel electrophoresis (PAGE) confirmed these results. We also tested the activity of glutathione S-transferase (GST) and observed the activity stimulated by isoproturon at 2-10 mg/kg.

Genotoxicity evaluation of water soil leachates by Ames test, comet assay, and preliminary Tradescantia micronucleus assay

Combining genotoxicity/mutagenicity tests and physico-chemical methodologies can be useful for determining the potential genotoxic contaminants in soil samples. The aim of our study was to evaluate the genotoxicity of soil by applying an integrated physico-chemical-biological approach. Soil samples were collected at six sampling points in a Slovenian industrial and agricultural region where contamination by heavy metals and sulphur dioxide (SO(2)) are primarily caused by a nearby power plant. The in vitro alkaline version of the comet assay on water soil leachates was performed with Caco-2 and HepG2 cells. A parallel genotoxicity evaluation of the samples was performed by Ames test using Salmonella typhimurium and the Tradescantia micronucleus test. Pedological analyses, heavy metal content determination, and different physico-chemical analyses, were also performed utilizing standard methodology. Water leachates of soil samples were prepared according to standard methods. Since only a battery of biotests with prokaryotic and eukaryotic organisms or cells can accurately estimate the effects of (geno)toxicants in soil samples and water soil leachates, a combination of three bioassays, with cells or organisms belonging to different trophic levels, was used. Genotoxicity of all six water soil leachates was proven by the comet assay on both human cell lines, however no positive results were detected by bacterial assay, Ames test. The Tradescantia micronucleus assay showed increase in micronuclei formation for three samples. According to these results we can assume that the comet assay was the most sensitive assay, followed by the micronucleus test. The Ames test does not appear to be sensitive enough for water soil leachates genotoxicity evaluations where heavy metal contamination is anticipated.

Genotoxic effects and induction of phytochelatins in the presence of cadmium in Vicia faba roots

This study investigates different effects in roots of Vicia faba (broad bean) after exposure to cadmium. Genotoxic effects were assessed by use of the well-known Vicia root tip micronucleus assay. Cytotoxic effects were evaluated by determining the mitotic index in root tip cells. Finally, molecular induction mechanisms were evaluated by measuring phytochelatins with HPLC. After hydroponical exposure of V. faba roots to a range of cadmium concentrations and during different exposure times, the results of this approach showed large variations, according to the endpoint measured: after 48 h of exposure, genotoxic effects were found between 7.5 x 10(-8) and 5 x 10(-7)M CdCl(2), and cytotoxic effects were observed between 2.5 x 10(-7) and 5 x 10(-7)M CdCl(2). Statistically significant phytochelatin (PC) concentrations were measured at >or=10(-6)M CdCl(2) for PC(2), and at >or=10(-5)M CdCl(2) for PC3 and PC4.

Induction of biochemical stress markers and apoptosis in transgenic Drosophila melanogaster against complex chemical mixtures: Role of reactive oxygen species

The study was aimed to investigate the effect of leachates of solid waste from a flashlight battery factory and a pigment plant on 70 kDa heat shock protein (Hsp70) expression, generation of reactive oxygen species (ROS), antioxidant enzymes activities and apoptosis in Drosophila. Third instar larvae of Drosophila melanogaster transgenic for hsp70 (hsp70-lacZ) were fed on diet mixed with leachates of solid wastes (0.05-2.0%, v/v) released from two industrial plants at three different pHs (7.00, 4.93 and 2.88) for 2-48 h. A concentration- and time-dependent significant change in Hsp70 expression, ROS generation, antioxidant enzymes activities and MDA content was observed in the exposed larvae preceding the antioxidant enzymes activities. Mitochondria-mediated, caspase-dependent apoptotic cell death in the larvae exposed to 1.0 and 2.0% leachates of flashlight battery factory was concurrent with a significant regression in Hsp70 expression and a higher ROS generation. A positive correlation drawn between ROS generation and apoptotic markers and a negative correlation between apoptotic markers and Hsp70 expression in these groups indicated the important role of ROS in the leachate-induced cellular damage. Hsp70 along with antioxidant enzymes offered protection to the organisms exposed to all the tested concentrations of the leachates of pigment plant waste and 0.5% leachate of flashlight battery factory in a cooperative manner when ROS generation was less induced. Conversely, higher levels of ROS generation in the organisms treated with 1.0 and 2.0% leachate of flashlight battery factory after 24 and 48 h resulted in regression of Hsp70 expression in them leading to cell death. The study suggests that (1) leachates of flashlight battery factory waste more adversely affected the organisms in comparison to the leachates of pigment plant waste. (2) Hsp70 may be used as a biomarker of cellular damage in organisms exposed to leachates. (3) Cell based assays using D. melanogaster as an in vivo model may provide important mechanistic information about the adverse effect of xenobiotics.

Micronucleus frequency and lipid peroxidation in Allium sativum root tip cells treated with gibberellic acid and cadmium

Gibberellic acid (GA(3)) is a very potent hormone whose natural occurrence in plants controls their development. Cadmium is a particularly dangerous pollutant due to its high toxicity and great solubility in water. In this study, the effect of GA(3) on Allium sativum root tip cells was investigated in the presence of cadmium. A. sativum root tip cells were exposed to CdNO(3) (50, 100, 200 microM), GA(3) (10-3 M), both CdNO(3) and GA(3). Cytogenetic analyses were performed as micronucleus (MN) assay and mitotic index (MI). Lipid peroxidation analysis was also performed in A. sativum root tip cells for determination of membrane damage. MN exhibited a dose-dependent increase in Cd treatments in A. sativum. GA(3) significantly reduced the effect of Cd on the MN frequency. MN was observed in GA(3) and GA(3) + 50 mum Cd treatments at very low frequency. MI slightly decreased in GA(3) and GA(3) + Cd treatments. MI decreased more in high concentrations of Cd than combined GA(3) + Cd treatments. The high concentrations of cadmium induce MN, lipid peroxidation and lead to genotoxicity in A. sativum. Current work reveals that the effect of Cd on genotoxicity can be partially restored with GA(3) application.

Effects of soil cadmium on growth, oxidative stress and antioxidant system in wheat seedlings (Triticum aestivum L.)

Effects of different concentrations of soil cadmium (0-33mg kg(-1)) on growth, oxidative stress, and antioxidant response of wheat seedlings (Triticum aestivum L.) were investigated using pot experiments. A slight stimulatory effect on seedling growth was observed, especially at low Cd concentrations (less than 3.3mg kg(-1)). Results of the electron paramagnetic resonance (EPR) determination showed a decrease in unstable free radical level in the leaves, followed by a significant increase with increasing Cd concentrations. Malondialdehyde (MDA) contents were significantly enhanced by a high Cd concentration. Activity levels of some antioxidant enzymes in the leaves, including superoxide dismutase (SOD, EC1.12.1.1), catalase (CAT, EC1.11.1.6), guaiacol peroxidase (GPX, EC1.11.1.7), ascorbate peroxidase (APX, EC1.11.1.11) and glutathione reductase (GR, EC1.6.4.2), did not change much at low Cd concentrations (less than 3.3mg kg(-1)), but fluctuated drastically at high Cd concentrations. GSH contents and GSH/GSSG ratios decreased at low Cd concentrations, then increased at high Cd concentrations. Wheat seedlings might overcompensate at low Cd concentrations, resulting in a low oxidative stress and a positive effect on growth. Changes in biochemical parameters would occur before any visible symptom of toxicity appeared, and the endpoint based on these parameters might be more sensitive or indicative than morphological observations in revealing the eco-toxicity of Cd. Based on the results of this study, we propose that the toxic critical value of soil Cd in inducing oxidative stress to wheat seedlings is between 3.3mg kg(-1) and 10mg kg(-1).

Leachates of municipal solid waste incineration bottom ash from Macao: heavy metal concentrations and genotoxicity

Heavy metals in municipal solid waste incineration bottom ash (MSWIBA) may leach into soil and groundwater and pose long-term risks to the environment. In this study, toxicity characteristic leaching procedure (TCLP) was carried out on the MSWIBA from Macao. Heavy metals in leachates were determined by inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma atomic emission spectrometry (ICP-AES), and genotoxicity of leachates was also evaluated by micronucleus (MN) assay with Vicia faba root tip cells. The results showed that the concentrations of aluminium (Al), manganese (Mn), cobalt (Co), cadmium (Cd) and mercury (Hg) in the leachates were less than 0.01 mg l(-1), and those of iron (Fe), copper (Cu) and molybdenum (Mo) were less than 0.1 mg l(-1). The concentrations of chromium (Cr), zinc (Zn), selemium (Se), strontium (Sr), barium (Ba) and caesium (Cs) were between 0.11 mg l(-1) and 2.19 mg l(-1). Lead (Pb) concentrations, in particular, reached as high as 19.6 mg l(-1), significantly exceeding the maximum concentration limit (5 mg l(-1) for lead by TCLP). Compared with the negative group, a significant increase of MN frequencies was observed in the leachate-exposed groups (P<0.05). With the increase of heavy metals in the leachates, the toxic effects on the Vicia faba root tip cells increased, implying that heavy metals were the main factors causing the genotoxic effects. Our results suggested that apart from chemical analysis, bioassays like the MN assay of Vicia faba root tip cells should also be included in a battery of tests to assess the eco-environmental risks of bottom ashes before decisions can be made on the utilization, treatment or disposal.

DNA damage induced in human peripheral blood lymphocytes by industrial solid waste and municipal sludge leachates

Exposure of humans to toxic compounds occurs mostly in the form of complex mixtures. Leachates, consisting of mixtures of many chemicals, are a potential risk to human health. In the present study, leachates of solid wastes from a polyfiber factory (PFL), an aeronautical plant (AEL), and a municipal sludge leachate (MSL) were assessed for their ability to induce DNA damage in human peripheral blood lymphocytes using the alkaline Comet assay. The leachates also were examined for their physical and chemical properties. Lymphocytes were incubated with 0.5-15.0% concentrations (pH range 7.1-7.4) of the test leachates for 3 hr at 37 degrees C, and treatment with 1 mM ethyl methanesulfonate served as a positive control. All three leachates induced significant (P < 0.05), concentration-dependent increases in DNA damage compared with the negative control, as measured by increases in Olive tail moment (arbitrary units), tail DNA (%), and tail length (mum). A comparison of these variables among the treatment groups indicated that the MSL induced the most DNA damage. Inductively coupled plasma emission spectrometry analysis of the leachates indicated that they contained high concentrations of heavy metals, viz. iron, manganese, nickel, zinc, cadmium, chromium, and lead. The individual, synergistic, or antagonistic effects of these chemicals in the leachates may be responsible for the DNA damage. Our data indicate that the ever-increasing amounts of leachates from waste landfill sites have the potential to induce DNA damage and suggest that the exposure of human populations to these leachates may lead to adverse health effects.

Analysis of mutations that alter HO sensing and transcription regulation properties of a global peroxide regulator OxyR in Xanthomonas campestris pv. phaseoli

OxyR5, from a Xanthomonas campestris pv. phaseoli H(2)O(2)-resistant mutant, contains the two mutations G197D and L301R. The protein exists in its oxidized-like form in the absence of oxidants as judged by the protein's ability to activate the ahpC promoter. Analysis of DNase I footprint patterns indicates that under reducing conditions OxyR5 and OxyRG197D bind to the target site in the ahpC promoter in a manner similar to oxidized wild-type OxyR. Site-directed mutagenesis showed that OxyR5 behaves like oxidized OxyR, independent of the highly conserved C residues at positions 199 and 208 where, in normal OxyR, a disulfide bond between these residues converts the protein from its reduced to the oxidized form. The presence of aspartic acid or valine residue at position 197 caused OxyR to behave like the oxidized form in uninduced cells. Changing D197 to A or T in OxyR5 resulted in proteins with similar properties to native OxyR. In vivo, OxyR5 probably locked in an oxidized-like conformation, resulting in continuous high-level activation of target genes in the OxyR regulon.

Cadmium-induced genotoxicity, cytotoxicity and lipid peroxidation in Allium sativum and Vicia faba

Cadmium (Cd) is one of the most toxic environmental pollutants affecting cytogenetically the various organisms. The cytogenetic damage in root tip cells exposed to cadmium nitrate (CdNO3) solutions at four different concentrations (1, 10, 100 and 200 microM) was evaluated with biological tests based on micronucleus (MN) assay in two plant species, Allium sativum and Vicia faba. Additionally to the cytogenetic analysis, lipid peroxidation analyses were performed in both A.sativum and V.faba roots. Cd enhanced the MN frequency in both A.sativum and V.faba root tip cells, but no dose-dependent. Induction of MN is not depending on CdNO3 concentrations. Besides, high concentrations of Cd decreased the mitotic index and caused the delay in mitosis stages in both plants, mainly in V.faba. On the other hand, lipid peroxidation was significantly enhanced with external Cd in V.faba. The results clearly indicate that high concentrations of cadmium induce the lipid peroxidation resulting in oxidative stress that may contribute to the genotoxicity and cytotoxicity of Cd ions.