The analysis of the possibility of using biological tests for assessment of toxicity of leachate from an active municipal landfill

One of the consequence of municipal waste deposition is the production of landfill leachate. Its volume and composition is determined by numerous factors, including waste composition, landfill age and the volume of precipitation. Leachate may contain a number of mineral and organic compounds, the volume of which must be controlled regularly. One of the methods of determining the toxicity of substances contained in landfill leachate is the use of biological tests, based − among others − on aquatic organisms sensitive to environmental contamination. The purpose of this study was to analyse the possibility of using ecotoxicological tests (supplementing the physical and chemical tests) for the purpose of assessment of landfill leachate toxicity. The tests were conducted at an operating municipal landfill in Stary Sącz (southern Małopolska Region, Poland N: 49°55’33”76, E: 20°65’68’70) from December 2015 to October 2016. The scope of the tests included the analysis of physical and chemical indicators as part of the landfill monitoring process, and also the analysis of additional selected indicators: namely the boron, barium and vanadium content. The selected ecotoxicological tests included tests using Daphnia magna Straus (Cladocera, Crustacea).Leachate tests conducted with the use of physical and chemical indicators have, for nearly twenty years, mainly demonstrated changes related to the age of the used landfill; besides increased boron and barium values, no evident contamination has been found, excluding the case of boron. However, a statistically significant correlation between the B and Ba contents and the amount of precipitation was determined. In two cases, the used biological tests have confirmed the toxicity of the leachate: in January and June 2016. In the same months, the highest and abnormal boron contents were measured, which could cause a toxic effect of leachates.     

Acute aquatic toxicity of tire and road wear particles to alga,daphnid, and fish

Previous studies have indicated that tire tread particles are toxic to aquatic species, but few studies have evaluated the toxicity of such particles using sediment, the likely reservoir of tire wear particles in the environment. In this study, the acute toxicity of tire and road wear particles (TRWP) was assessed in Pseudokirchneriella subcapita, Daphnia magna, and Pimephales promelas using a sediment elutriate (100, 500, 1000 or 10000 mg/l TRWP). Under standard test temperature conditions, no concentration response was observed and EC/LC₅₀ values were greater than 10,000 mg/l. Additional tests using D. magna were performed both with and without sediment in elutriates collected under heated conditions designed to promote the release of chemicals from the rubber matrix to understand what environmental factors may influence the toxicity of TRWP. Toxicity was only observed for elutriates generated from TRWP leached under high-temperature conditions and the lowest EC/LC₅₀ value was 5,000 mg/l. In an effort to identify potential toxic chemical constituent(s) in the heated leachates, toxicity identification evaluation (TIE) studies and chemical analysis of the leachate were conducted. The TIE coupled with chemical analysis (liquid chromatography/mass spectrometry/mass spectrometry [LC/MS/MS] and inductively coupled plasma/mass spectrometry [ICP/MS]) of the leachate identified zinc and aniline as candidate toxicants. However, based on the high EC/LC₅₀ values and the limited conditions under which toxicity was observed, TRWP should be considered a low risk to aquatic ecosystems under acute exposure scenarios.     

Acute toxicity tests using rotifers. III. Effects of temperature,strain, and exposure time on the sensitivity of Brachionus plicatilis

As part of the development of a standardized acute toxicity test, the effect of cyst age, strain, temperature, and exposure time on the toxicity of 21 chemicals to the estuarine rotifer Brachionus plicatilis was investigated. Toxicity was chemical specific, with LC₅₀s ranging from 0.061 mg · L^?1 for mecury to 598 mg · L^?1 for 2,4-dichlorophenoxyacetic acid. Intralaboratory coefficients of variation averaged 11%, at least three times lower than for other aquatic invertebrate acute tests. The age of rotifer cysts stored up to 27 months had no effect on the sensitivity of test animals, but significant differences in sensitivity were detected among rotifer strains. Test temperatures of 25, 30, and 35°C generally yielded lower LC₅₀s than at 20°C. LC₅₀s decreased by 80–90% for cadmium and pentachlorophenol when toxicant exposure time was increased from 24 to 72 h. Life table analysis of rotifer survival in the controls revealed that 72 h is the longest acute test possible without feeding. A comparison of the sensitivity of the rotifer test to that of sea urchin (Arabacia punctulata) early embryo, sea urchin sperm cell, Microtox®, and Mysidopsis bahia tests revealed comparability for several compounds. However, no species is consistently the most sensitive to all compounds.     

The Microtox as an alternative assay in the acute toxicity assessment of water pollutants

The toxicity of 15 chemicals was determined with the Microtox Assay System (MAS). Subsequently the sensitivity of the MAS was compared with that of standard aquatic toxicity tests, comprising 20 different species including recommended test species. The MAS yielded fairly replicable results which were comparable with those obtained with the standard tests. As the MAS does not require the culturing of test organisms and takes about 5% of the actual work involved in the standard procedures, it is suggested to use the MAS as a prescreening tool in the hazard assessment of chemicals.     

An assessment of the potential of the microbial assay for risk assessment (MARA) for ecotoxicological testing

Rapid microscale toxicity tests make it possible to screen large numbers of compounds and greatly simplify toxicity identification evaluation and other effect directed chemical analyses of effluents or environmental samples. Tests using Vibrio fischeri (such as Microtox?) detect toxicants that cause non-specific narcosis, but are insensitive to other important classes of contaminants. The microbial assay for risk assessment (MARA) is a 24 h multi-species test that seeks to address this problem by using a battery of ten bacteria and a fungus. But there has been little independent evaluation of this test, and there is no published information on its sensitivity to pesticides. Here, we assess the performance of MARA using a range of toxicants including reference chemicals, fungicides and environmental samples. Mean MARA microbial toxic concentrations and IC₂₀s (20% Inhibitory concentrations) indicate the toxicant concentrations affecting the more sensitive micro-organisms, while the mean IC₅₀ (50% Inhibitory concentration) was found to be the concentration that was toxic to most MARA species. For the two fungicides tested, the yeast (Pichia anomalia) was the most sensitive of the ten MARA species, and was more sensitive than the nine other yeasts tested. The test may be particularly valuable for work with fungicides. Mean MARA IC₅₀s were comparable to values for nine other yeast species and the lowest individual IC₅₀s for each toxicant were comparable to reported IC₅₀s for Daphnia magna, Selenastrum capricornutum and Microtox? bioassays. MARA organisms exhibited more variable sensitivities, with the most sensitive organism being different for different samples, enhancing the likelihood of toxicity detection and giving a toxicity “fingerprint” that may help identify toxicants. The test, therefore, has great potential and would be valuable for ecotoxicological testing of pollutants.     

Chemical fate,bioconcentration, and environmental effects testing: Proposed testing and decision criteria

Chemicals should have a minimum amount of available chemical fate, bioconcentration, and environmental effects data to identify those chemicals with potentially problematic environmental partitioning or persistence, or those with potential to bioconcentrate or cause adverse effects. Professional judgment, estimates of a chemical's mode(s) of action or mechanism of action, and its susceptibility to rapid transport or transformation should be utilized to determine the types of chemical fate, bioconcentration, and environmental effects data that should be available. Data-supported decision criteria should be used to develop additional data to characterize the persistence, bioconcentration, and adverse effects of chemicals that have been identified as potentially problematic. To facilitate an understanding of minimum chemical fate and bioconcentration data that should be available, recommended chemical fate and bioconcentration data from previously published testing schemes or approaches were evaluated. For environmental effects data, the types of organisms recommended for developing aquatic toxicity data in previously published testing schemes or approaches were evaluated. To facilitate an understanding of available testing decision criteria, those criteria that were used (as of December 31, 1988) to propose or require chemical fate, bioconcentration, on aquatic toxicity tests under section 4 of the Toxic Substances Control Act and those criteria recommended in previously reported testing schemes were evaluated. Based on this comprehensive evaluation it was possible to propose (1) a base set of chemical fate and aquatic toxicity tests, (2) organisms for conducting aquatic toxicity tests, and (3) decision logic and testing scheme for developing chemical fate and aquatic toxicity test data.     

Comparison of the susceptibility of 11 freshwater species to 8 chemical compounds. II. (Semi)chronic toxicity tests

The relative susceptibility of 11 taxonomically different species (bacteria, algae, plants, crustaceans, insects, hydrozoans, molluscs, fish and amphibians) to chemicals was determined by comparing the (semi)chronic toxicity data of 8 test substances. Marked differences were observed in the susceptibility among the species with respect to the individual test compounds (up to a factor 10 000). In contrast to this, differences were smaller (less than a factor 50) when the relative susceptibility based on all separate toxicity data of the compounds was taken into account. The results showed that a test set with an alga, a crustacean and an egg-laying fish species will generally give a good impression of the toxic potential of chemicals to aquatic life.Additionally, the use of data derived from acute and chronic toxicity tests to estimate the impact of chemical substances on aquatic ecosystems is briefly discussed. It is concluded that for most chemicals the difference in short- and long-term toxicity data on the same species is less than the difference in the susceptibility of various species.     

Using Proales similis (Rotifera) for toxicity assessment in marine waters

There is a need to develop more animal species for assessing toxicity in marine environments. Cyst‐based toxicity tests using invertebrates are especially fast, technically simple, cost‐effective, and sensitive to a variety of toxicants. Over the past 30 years, a variety of toxicity endpoints have been measured using the marine rotifer Brachionus plicatilis hatched from cysts, including mortality, reproduction, ingestion, swimming, enzyme activity, and gene expression. A consensus has developed that the most ecologically relevant toxicity measurements should be made using more than one species. Furthermore, it has been noted that the rotifer species toxicant sensitivity distribution is much broader than which endpoint is measured. This implies that toxicity should be measured with the simplest, fastest, least expensive test available on as many species as feasible. If a battery of test species is to be used to estimate toxicity, diapause egg‐based toxicity tests that do not require culturing of test animals will be key. In this paper, we describe how diapause eggs of a new marine rotifer, Proales similis, can be produced, stored and hatched under controlled conditions to produce animals for toxicity tests. Methods are described for quantifying the toxicity of copper, mercury and cadmium based on mortality, ingestion, reproduction, and diapause egg hatching endpoints. We found that reproduction and ingestion endpoints were generally more sensitive to the metals than mortality or diapause egg hatching. When the copper sensitivity of P. similis was compared to Brachionus manjavacas and B. plicatilis using an ingestion test, similar EC50s were observed. In contrast, the B. rotundiformis ingestion EC50 for copper was about 4× more sensitive. Although diapause egg hatching was not the most sensitive endpoint, it is the most ecologically relevant for assessing sediment toxicity. Our discovery of diapausing eggs in the P. similis life cycle has created a conundrum. We have not observed males or sex in P. similis populations, which is a direct contradiction to the orthodox view of the monogonont rotifer life cycle. Work is needed to clarify how diapause egg production is accomplished by P. similis and whether sexual reproduction is involved.     

Differences in susceptibility of five cladoceran species to two systemic insecticides, imidacloprid and fipronil

Differences in susceptibility of five cladocerans to the neonicotinoid imidacloprid and the phenyl-pyrazole fipronil, which have been dominantly used in rice fields of Japan in recent years, were examined based on short-term (48-h), semi-static acute immobilization exposure tests. Additionally, we compared the species sensitivity distribution (SSD) patterns of both insecticides between two sets of species: the five tested cladocerans and all other aquatic organisms tested so far, using data from the ECOTOX database of U.S. Environmental Protection Agency (USEPA). The sensitivity of the test species to either imidacloprid or fipronil was consistent, spanning similar orders of magnitude (100 times). At the genus level, sensitivities to both insecticides were in the following descending order: Ceriodaphnia > Moina > Daphnia. A positive relationship was found between body lengths of each species and the acute toxicity (EC₅₀) of the insecticides, in particular fipronil. Differences in SSD patterns of imidacloprid were found between the species groups compared, indicating that test cladocerans are much less susceptible than other aquatic species including amphibians, crustaceans, fish, insects, mollusks and worms. However, the SSD patterns for fipronil indicate no difference in sensitivity between cladocerans tested and other aquatic organisms despite the greater exposure, which overestimates the results, of our semi-static tests. From these results, Ceriodaphnia sp. should be considered as more sensitive bioindicators (instead of the standard Daphnia magna) for ecotoxicological assessments of aquatic ecosystems. In addition, we propose that ecotoxicity data associated with differences in susceptibility among species should be investigated whenever pesticides have different physicochemical properties and mode of action.     

Which is most sensitive? Assessing responses of mice and rats in toxicity bioassays

Rodent species are commonly used in traditional toxicology testing guidelines to predict human health toxicity outcomes. The use of a consistent species in test guidelines is important for maintaining consistency and comparability between tests and testing guidelines. This recommendation was operationalized for this study as the implicit assumption of uniform species and species-sex sensitivities. This investigation analyzed the uniformity assumption using data from National Toxicology Program Technical Reports (and where applicable Toxicity Reports), which provide data from both short-term and chronic rodent toxicity tests. These data were extracted and modeled using the Environmental Protection Agency’s Benchmark Dose Software. Minimum best-fit benchmark doses (BMD) and benchmark dose lower limits (BMDL) were determined and a minimum best-fit BMD10 and BMDL10 estimated for every chemical and study duration. Endpoints of interest included non-neoplastic lesions, final mean body weights, and mean organ weights. The distribution of findings was then assessed to determine the most sensitive species and species-sex combinations associated with the minimum best-fit BMDL10. Data indicated that species and species-sex sensitivity for this group of chemicals is not uniform and that rats are significantly more sensitive than mice for non-cancerous outcomes observed, depending upon study duration. There are also indications that male rats may be more sensitive than other species-sex groups in certain situations.     

Comparison of respiration and luminescent tests in bacterial toxicity assessment

The toxicity assessment of chemicals on complex microbial communities are generally preferred to toxic tests conducted with pure cultures of bacteria. The purpose of this study is to compare the “Respiration” test studying metabolic criteria of mix bacterial populations and the “Microtox” test using lyophilized cultures of luminescent bacteria. The inhibition of oxygen consumption was compared with the inhibition of the bioluminescence of Photobacterium phosphoreum. In the first part of this study, the methodology of the “Respiration” test and the “Microtox” test was improved to optimize their performance in toxicity assessment. In the second part, toxicity of an organic chemical, the 3,5-Dichlorophenol, and an inorganic chemical, copper sulfate, was evaluated with the two tests. Results were compared and characteristics of the testing methods are discussed according to their sensitivity, reproducibility, representativity and ease of execution. The repeatability study for the “Respiration” test and the “Microtox” test gives variation coefficients less than 15% and 10% respectively. The variation coefficients concerning the reproducibility study are found to be 15% or 18% for the “Respiration” test, 5% or 28% for the “Microtox” test, depending on the tested toxicant. These two toxicity tests are easy to perform. But the “Microtox” test offers the advantage of being more sensitive and much faster. On the other hand, the “Respiration” test which was conducted on a microbial community is probably more representative of microflora in rivers.     

Antiestrogenicity and estrogenicity in leachates from solid waste deposits

A great deal of effort has been devoted to developing new in vitro and in vivo methods to identify and classify endocrine disrupting chemicals that have been identified in environmental samples. In this study an in vitro test based on recombinant yeast strains transfected with genes for the human estrogen receptor α was adapted to examine the presence of estrogenic and antiestrogenic substances in six Swedish landfill leachates. Antiestrogenic effects were measured as inhibition of the estradiol induced response with the human estrogen receptor α, and quantified by comparison with the corresponding inhibitory effects of a known antiestrogen, hydroxytamoxifen. The estrogenicity was within the range of that determined in domestic sewage effluents, from below the limit of detection to 29 ng estradiol units L^?1. Antiestrogenicity was detected in some of the investigated landfill leachates, ranging between <38 and 3800 μg hydroxytamoxifen equivalents L^?1. There was no apparent relation between the type of waste deposited on the landfills and the antiestrogenic effect. Fractionation of a landfill leachate showed that estrogenic compounds were located in two dominant fractions. Three estrogenic compounds were found that accounted for the estrogenic activity in extracts of leachates: bisphenol A, estradiol, and ethinylestradiol. The bisphenol may have been released from decomposing plastic waste and the estrogenic steroids from earlier deposits of municipal sewage sludge and pharmaceutical waste. Fractionation of leachates from three parts of a landfill showed that the antiestrogenic activity was distributed in at least four fractions and somewhat different in different flows of leachate. This indicated a heterogeneous mixture of antiestrogenic substances. © 2009 Wiley Periodicals, Inc. Environ Toxicol, 2011.     

Toxicity analysis of leachates from hazardous wastes via microtox and daphnia magna

One of the most common ways of surface and ground water contamination from hazardous wastes is through its leachates. Toxicity is a meaningful parameter allowing an integrated evaluation of the potential danger of leachates. Two bioassays were considered for measuring toxicity: Microtox and Daphnia magna. The toxicity was measured on leachates obtained, using different leaching procedures, from wastes of a pesticide manufacturing industry and sludge from electroplating wastewater. Twenty-two tests were carried out, measuring IC50 for D. magna and EC50 for Microtox. Both bioassays were compared using three toxicity criteria. The first criterium is classification on toxic/non-toxic at 25 and 50% leachate concentration. The second criterium is classification on percent ranks, and the third on log ranks. Considering these criteria, the agreement between both bioassays is within a 75–85%. It is shown that both, Microtox and D. magna assays could be used as toxicity indicators for the wastes considered. The sensitivity of the bioassays is different depending on leachate composition. In all samples, the leachate concentration of chemicals was measured.     

Cyst-based toxicity tests. IX. The potential of Thamnocephalus platyurus as test species in comparison with Streptocephalus proboscideus (crustacea: Branchiopoda: Anostraca)

The potential of the larvae of the freshwater anostracan crustacean Thamnocephalus platyurus has been evaluated as an alternative to those of the related species Streptocephalus proboscideus, used so far as the test organism in the standard Streptoxkit F test. In line with the former cyst-based toxicity test method, the hatching of dried T. platyurus eggs, the molting of larvae, and the sensitivity of the latter to toxicants were assessed. The acute toxicity of 10 pure chemicals, 4 solid waste leachates, and 5 sediment pore waters to T. platyurus nauplii was determined according to the standard Streptoxkit F test protocol. Hatching success and reliability of T. platyurus cysts proved better than that of S. proboscideus cysts after 20 h incubation in standard conditions; the hatching percentage after 24 h was slightly improved by diluting the Environmental Protection Agency medium to 1:8 with deionized water. The sensitivity of T. platyurus nauplii to pure toxicants and wastes was at least equal to, and in many cases even higher than, that of S. proboscideus larvae. Generally, precision of the toxicity tests with T. platyurus was better than that of the S. proboscideus assay, especially for the pure chemicals tested. Consequently, the standard operational testing protocol of the Streptoxkit F has been slightly modified with replacement of S. proboscideus by T. platyurus as a test species. The Streptoxkit F has consequently been renamed to Thamnotoxkit F for use in cost-effective routine acute toxicity testing of chemicals and wastes. © by John Wiley & Sons, Inc.     

Increased reproductive toxicity of landfill leachate after degradation was caused by nitrite

Leachate from the landfill Lindbodarna was suspected to cause reproductive effects on fish in a Swedish lake, called Molnbyggen. The acute toxicity of this landfill leachate is caused by ammonia. In the present study the acute and chronic toxicity of the leachate from the landfill was tested with Ceriodaphnia dubia before and after treatment, either with (inoculated) or without addition of microorganisms from activated sludge, in both 2000 and 2001. On both occasions, the acute toxicity decreased after treatment, more rapidly with inoculum than without, and the cause of the decrease was mainly explained by decreasing concentrations of ammonia. However, the chronic toxicity decreased after treatment with inoculum but increased after treatment without inoculum. Therefore, we performed a series of acute and reproductive tests with ammonia, nitrite and nitrate on C. dubia, and the 24-h EC50s were 1.0, 2.7 and 59 mM, respectively, which are consistent with literature data. However, the chronic toxicity of these compounds gave quite a different picture with 8-day EC50s for reproduction of 3.0 mM for ammonia, 0.016 mM for nitrite and 1.5 mM for nitrate. Thus, the acute-chronic ratios for these compounds were 0.33 for ammonia, 170 for nitrite and 39 for nitrate. These findings show that reproduction is more sensitive than survival for both nitrite and nitrate, and that nitrite is the more hazardous of the two. This implies that the chronic and reproductive toxicity of nitrite and nitrate on zooplankton may in fact increase effects of eutrophication. In this study the toxicity of the fresh leachate was dominated by ammonia, but after treatment the contribution of nitrite increased, and especially the chronic toxicity of the treated landfill leachate was dominated by nitrite toxicity.     

Acute aquatic toxicity of two commonly used fungicides to midwestern amphibian larvae

Fungicide usage has increased globally in response to the rise in fungal pathogens, especially in the agricultural sector. However, research examining the toxicity of fungicides is still limited for many aquatic species. In this study, we examined the acute toxicity of two widely used fungicides, chlorothalonil and pyraclostrobin, on six North American larval amphibian species across multiple families using 96-h LC50 tests. We found that pyraclostrobin was approximately 3.5x more toxic than chlorothalonil; estimated LC50 values ranged from 5–18?µg/L for pyraclostrobin and 15–50?µg/L for chlorothalonil. Comparing across amphibian groups, we found that salamanders were 3x more sensitive to pyraclostrobin than anuran species and equally as sensitive to chlorothalonil. Notably, our estimated LC50 values within the range of the expected environmental concentration for these fungicides suggesting environmental exposures could lead to direct mortality in these species. Given the widespread and increasing usage of fungicides, additional work should be conducted to assess the general risk posed by these chemicals to amphibian and their associated aquatic habitats.

     

Evaluation of the toxic and genotoxic potential of landfill leachates using bioassays

Landfill leachates are liquid effluents with elevated concentrations of chemical compounds that can cause serious environmental pollution. In the south of the state of Santa Catarina, Brazil, a sanitary landfill was installed that employs a system of anaerobic/facultative lagoons for the treatment of its leachate. The present work examined the toxic and genotoxic potential of untreated and treated landfill leachates using bioassays. The chemical, toxic, genotoxic and mutagenic properties of the untreated leachate and the treated leachate were determined. Examination of the chemical properties showed a marked decrease in parameters after treatment, as well as in toxicity towards all the organisms tested. The results of the comet assay demonstrated that both leachates showed genotoxicity in all of the organisms tested, indicating the persistence of genotoxic substances even after treatment. A significant decrease in micronucleated cells was detected in Geophagus brasiliensis exposed to the treated leachate compared to untreated.     

Genotoxicity assay of landfill leachates

Environmental burden with genotoxic chemicals is increasingly becoming a serious problem mainly due to hazardous waste dumping and industrial effluents. The Mutatox® mutagenicity assay was validated with known mutagen for its efficacy in the detection of direct mutagens and S-9 activated promutagens and applied to the complex environmental samples of landfill leachates from the Al-Sulaibiyah solid waste disposal site in Kuwait. The leachate samples from borehole 3 collected between December 1994 and May 1995 (cold and rainy months) showed genotoxic response in direct assay, indicating the presence of direct acting mutagens, whereas the samples collected between June and September 1995 (hot and dry months) were active in both direct and S-9 activated assay, also showing the presence of promutagens. Thus the leachate from the landfill, which is not equipped with a leachate collection and treatment facility, was found capable of exerting genotoxic effects that may influence the biota of the receiving system. © 1998 John Wiley & Sons, Inc. Environ Toxicol Water Qual 13: 127–131, 1998     

The interaction effects of toxic chemical combinations on chlorella ellipsoidea

The hazardous chemicals that have been released into the aquatic environment may disturb the balance of the aquatic ecosystem. Chemicals do not exist in single pure form, but occur in mixtures in the environment. Consequently, their effects on organisms living in the aquatic environment are primarily due to the combined toxicities. In this study, the interaction effects between chemicals such as copper, cadmium, chromium and pentachlorophenol on the growth of green algae Chlorella ellipsoidea, were investigated using a batch culture. Growth rate was a more sensitive index than standing crop at a given time for detecting the toxicity of chemicals. The EC₅₀ values obtained from dry weight, were higher than those obtained from ATP, chlorophyll-a, chlorophyll-b, carotenoid as growth indices for algal density. The toxicity of each chemical was dependent on the test period. The inhibition rate of PCP and Cu in comparison with the control for the exposure time of 24 hours was higher than that for the exposure time of 48 hours. The inhibition rate of Cr and Cd for 48 hours was higher than that for 24 hours. The toxic intensity of chemicals was, in order, PCP, Cu, and Cr, without exception. The toxicity of Cd was changeable depending upon the indices used. The method modified by Stratton (1983) and the isobologram method were used to determine the modes of interaction effects of the chemical combinations. These two methods led to the same results, with three exceptions. A synergistic effect was observed for combinations between Cr and PCP, between Cu and Cd, and between Cu and Cr; while an antagonistic effect was observed for combinations between Cd and PCP, between Cu and PCP, and between Cd and Cr within some concentration ranges.     

Toxicity assessment of industrial effluents from S. Paulo state,Brazil, using short-term microbial assays

Microorganisms have demonstrated several attributes that make them attractive for use in quick screening of effluents and chemicals for toxicity. The aim of this study was to evaluate the acute toxicity and mutagenicity of industrial effluents from São Paulo State using short-term microbial bioassays. Samples of industrial effluents and receiving waters were analyzed for acute toxicity by the Microtox system, a motility test using Spirillum volutans, growth inhibition of Pseudomonas fluorescens, and dehydrogenase assay; for mutagenicity, these samples were analyzed by Salmonella typhimurium (Ames test), Escherichia coli WP₂, and Saccharomyces cerevisiae reversion mutation assays. Among the acute toxicity assays carried out in this study, the Microtox and S. volutans tests showed good sensitivity and general good agreement with the Daphnia similis assay, which demonstrates that these tests are potentially useful as toxicity indicators for the industrial effluents and receiving waters considered. In relation to mutagenicity assays, good results were obtained with the three methods tested. The detection of mutagens in the industrial effluents considered indicates that some constituents of these waste waters discharged in receiving waters can cause adverse biological effects and could be deleterious from a public health standpoint. The data of this research emphasize the importance of acute toxicity and mutagenicity assays as supplementary approaches for a rapid and efficient action in water pollution control, and for evaluation of potential toxic chemical effects.