Using Quantitative Structure–Activity Relationships to Support the Assessment of the Environmental Fate and Aquatic Toxicity of a Series of Methacrylic Acid Esters

Methacrylic acid esters or methacrylates (with C1 to 8 alkyl side-chains) are a group of compounds used in the manufacture of resins and plastics. Releases to the atmosphere, surface waters, or soil can come about during manufacturing, use, transport, and storage activities. Given the potential for environmental exposures, an examination into factors that control the distribution, fate, and toxicity of methacrylates is warranted. Methacrylates are relatively volatile compounds that are easily and rapidly degraded in the atmosphere and in oxic surface waters and sediments, and so are not considered persistent. Aquatic organisms are also able to metabolize methacrylates as demonstrated by estimated bioconcentration factors of < 45 for the acid and the C1-4 esters, and a measured bioconcentration factor (BCF) for 2-EHMA. Thus, the methacrylates are not considered bioaccumulative. Acute and chronic aquatic toxicity data for the methacrylates were assembled. Quantitative structure–activity relationships (QSARs) were developed with the acute and chronic fish, invertebrate, and algal datasets to support the toxicity assessment of the methacrylates (with log octanol-water partition coefficients used as surrogates for structures). The data show the methacrylates to be of low to moderate toxicity with all acute LC/EC50 values and chronic no observed effect concentrations ranging from about 2 to 170 mg/l for the acid and C1-4 esters, and 0.1 mg/l up to the aqueous solubility limit (about 2 mg/l) for the C8 ester. The measured toxicity data and the data estimated from the QSARs were used to develop predicted no effect concentrations in water and sediment for methacrylic acid and the C1-C8 esters.     

水环境中工程纳米颗粒物的生态毒理学机理及理想模式生物的筛选

随着纳米技术产业的高速发展,大量工程纳米颗粒物(Engineering nano-particles,ENPs)被排放到自然水环境中,因此对其进行生态毒性及环境风险的研究尤为迫切。综述了ENPs在水环境中的毒理学机理及理想模式生物筛选的研究进展。目前的研究表明ENPs的毒性作用机制主要包括两方面:一是影响细胞信号通路,二是氧化应激造成基因表达的变化。此外,光催化活性、细胞表面附着、溶解特性、表面特征、赋存形态、溶剂效应及与其他环境污染物的协同作用也是可能的毒性作用机理。模式生物的筛选与确定在纳米生态毒理学研究中极为重要。鱼类作为水环境中普遍存在的脊椎动物,群落庞大,其具有行为端点敏感性高、且在生物毒性实验中存在明显的量效关系等特征,被认为是研究ENPs生态毒理学最适合的水生模式生物。研究表明针对在ENPs影响下的未成年鱼类的行为特征研究比传统的胚胎发育及致死率研究更为有效。无脊椎动物和浮游植物同样在各种水环境中普遍存在,对环境污染物极为敏感,且对有害物质具有显著的富集放大效应,因此作为模式生物也具有一定的优势。     

Are Pharmaceuticals with Evolutionary Conserved Molecular Drug Targets More Potent to Cause Toxic Effects in Non-Target Organisms?

The ubiquitous use of pharmaceuticals has resulted in a continuous discharge into wastewater and pharmaceuticals and their metabolites are found in the environment. Due to their design towards specific drug targets, pharmaceuticals may be therapeutically active already at low environmental concentrations. Several human drug targets are evolutionary conserved in aquatic organisms, raising concerns about effects of these pharmaceuticals in non-target organisms. In this study, we hypothesized that the toxicity of a pharmaceutical towards a non-target invertebrate depends on the presence of the human drug target orthologs in this species. This was tested by assessing toxicity of pharmaceuticals with (miconazole and promethazine) and without (levonorgestrel) identified drug target orthologs in the cladoceran Daphnia magna. The toxicity was evaluated using general toxicity endpoints at individual (immobility, reproduction and development), biochemical (RNA and DNA content) and molecular (gene expression) levels. The results provide evidence for higher toxicity of miconazole and promethazine, i.e. the drugs with identified drug target orthologs. At the individual level, miconazole had the lowest effect concentrations for immobility and reproduction (0.3 and 0.022 mg L⁻¹, respectively) followed by promethazine (1.6 and 0.18 mg L⁻¹, respectively). At the biochemical level, individual RNA content was affected by miconazole and promethazine already at 0.0023 and 0.059 mg L⁻¹, respectively. At the molecular level, gene expression for cuticle protein was significantly suppressed by exposure to both miconazole and promethazine; moreover, daphnids exposed to miconazole had significantly lower vitellogenin expression. Levonorgestrel did not have any effects on any endpoints in the concentrations tested. These results highlight the importance of considering drug target conservation in environmental risk assessments of pharmaceuticals.     

Genetically modified crops and aquatic ecosystems: considerations for environmental risk assessment and non-target organism testing

Environmental risk assessments (ERA) support regulatory decisions for the commercial cultivation of genetically modified (GM) crops. The ERA for terrestrial agroecosystems is well-developed, whereas guidance for ERA of GM crops in aquatic ecosystems is not as well-defined. The purpose of this document is to demonstrate how comprehensive problem formulation can be used to develop a conceptual model and to identify potential exposure pathways, using Bacillus thuringiensis (Bt) maize as a case study. Within problem formulation, the insecticidal trait, the crop, the receiving environment, and protection goals were characterized, and a conceptual model was developed to identify routes through which aquatic organisms may be exposed to insecticidal proteins in maize tissue. Following a tiered approach for exposure assessment, worst-case exposures were estimated using standardized models, and factors mitigating exposure were described. Based on exposure estimates, shredders were identified as the functional group most likely to be exposed to insecticidal proteins. However, even using worst-case assumptions, the exposure of shredders to Bt maize was low and studies supporting the current risk assessments were deemed adequate. Determining if early tier toxicity studies are necessary to inform the risk assessment for a specific GM crop should be done on a case by case basis, and should be guided by thorough problem formulation and exposure assessment. The processes used to develop the Bt maize case study are intended to serve as a model for performing risk assessments on future traits and crops.     

Toxicity analysis of freshwater and marine sediments with meio- and macrobenthic organisms: a review

Benthic metazoans play a key role as test organisms in toxicity analyses of aquatic ecosystems. This report gives an overview of the species of benthic metazoans used for the assessment of toxicity in freshwater and marine sediments, as well as of the criteria relevant to the choice between test species and procedures. The main applications of these organisms are mono-species bioassays, test-batteries, analyses of benthic communities and bioaccumulation studies. Sediment toxicity assays, including acute and chronic exposures, have been developed for nematodes, insects, oligochaetes, polychaetes, crustaceans, molluscs and echinoderms. At least 30 species of freshwater and 71 species of marine and estuarine benthic metazoans have thus far been used in sediment toxicity bioassays. Although aquatic pollution is a world-wide problem, most sediment toxicity bioassays have been developed for organisms native to Europe and North America. The most common bioassay endpoints are mortality, development, growth and behavioural responses. The value of genetic, biochemical, physiological and pathological responses as toxicity endpoints is currently being investigated. The quest for additional test species and protocols is still a worthwhile endeavour in sediment ecotoxicology.     

Progress of research on the toxicology of antibiotic pollution in aquatic organisms

Antibiotics are widely used to improve human and animal health and treat infections. Antibiotics are often used in livestock farms and fisheries to prevent diseases and promote growth. Recently, there has been increasing interest in the presence of antibiotics in aquatic environments. Low levels of antibiotic components are frequently detected in surface water, seawater, groundwater, and even drinking water. Antibiotics are consistently and continually discharged into the natural environment as parent molecules or metabolites, which are usually soluble and bioactive, and this results in a pseudo and persistent pollution. The effects of environmental antibiotic toxicity on non-target organisms, especially aquatic organisms, have become an increasing concern. Although antibiotics have been detected worldwide, their ecological and developmental effects have been poorly investigated, particularly in non-target organisms. This review describes the toxicity and underlying mechanism of antibiotic contamination in aquatic organisms, including the effects on vertebrate development. A considerable number of antibiotic effects on aquatic organisms have been investigated using acute toxicity assays, but only very little is known about the long-term effects. Aquatic photosynthetic autotrophs, such as Pseudokirchneriella subcapitata, Anabaena flos-aquae, and Lemna minor, were previously used for antibiotic toxicity tests because of low cost, simple operation, and high sensitivity. Certain antibiotics show a different degree of potency in algal toxicity tests on the basis of different test algae. Antibiotics inhibit protein synthesis, chloroplast development, and photosynthesis, ultimately leading to growth inhibition; some organisms exhibit growth stimulation at certain antibiotic concentrations. Daphnia magna and other aquatic invertebrates have also been used for checking the toxicity priority of antibiotics. When investigating the acute effect of antibiotics (e.g., growth inhibition), concentrations in standard laboratory organisms are usually about two or three orders of magnitude higher than the maximal concentrations in the aquatic environment, resulting in the underestimation of antibiotic hazards. Vertebrate organisms show a promising potential for chronic toxicity and potentially subtle effects of antibiotics, particularly on biochemical processes and molecular targets. The adverse developmental effects of macrolides, tetracyclines, sulfonamides, quinolones, and other antibiotic groups have been evaluated in aquatic vertebrates such as Danio rerio and Xenopus tropicalis. In acute toxicity tests, low levels of antibiotics have systematic teratogenic effects on fish. The effects of antibiotics on oxidative stress enzymes and cytochrome P450 have been investigated. Cytotoxicity, neurotoxicity, and genotoxicity have been observed for certain antibiotic amounts. However, there are no firm conclusions regarding the chronic toxicity of antibiotics at environmentally relevant levels because of the lack of long-term exposure studies. Herein, future perspectives and challenges of antibiotic toxicology were discussed. Researchers should pay more attention to the following points: chronic toxicity and potentially subtle effects of environmentally relevant antibiotics on vertebrates; effects of toxicity on biochemical processes and mode of action; combined toxicity of antibiotics and other antibiotics, metabolites, and heavy metals; and environmental factors such as temperature and pH.     

A Weight of Evidence Approach to the Aquatic Hazard Assessment of Bisphenoi A

Bisphenol A (BPA; 4,4-isopropylidene diphenol) is a chemical intermediate used primarily in the production of epoxy resins and polycarbonate products. BPA has been identified in surface waters and, hence, has been the subject of considerable research into its potential effects on aquatic organisms. Available literature on the aquatic toxicity of BPA was reviewed for quality against European Union TGD and Organization of Economic Cooperation and Development GLP principles. From this review, studies of suitable quality covering numerous ecologically relevant endpoints were identified to evaluate the survival, growth, and reproductive success of aquatic organisms exposed to BPA. Those studies yielded approximately 70 no observed effect concentrations (ranging from 16 to 3640 μg/L) and lowest observed effect concentrations (160 to 11,000 μg/L) that were considered in this weight of evidence assessment. Across all data, adverse effects on survival, growth, and reproduction occurred only at concentrations of 160 μg/L and above. Secondary biochemical (e.g., vitellogenin induction) and morphological (e.g., gonad histology) data provide insight into mechanisms of action, but do not correlate with apical endpoints related to survival, growth, and reproduction. Comparing the weight of the evidence of the aquatic toxicity data that showed chronic effects at 160 μg/L and higher with typical surface water concentrations in the range of 0.001 to 0.10 μg/ L, BPA is unlikely to cause adverse effects on aquatic populations or ecosystems.     

使它隆对草鱼、鲢鱼和鲫鱼的急性毒性

【背景】有关农药对水生生物的毒性和影响已有大量的报道,但关于使它隆对水生生物影响的研究较少。【方法】采用半静态法测试了使它隆对草鱼、鲢鱼和鲫鱼的急性毒性,并计算使它隆对草鱼、鲢鱼和鲫鱼的安全浓度。试验过程中,水温保持在25℃±1℃。【结果】随着受试鱼苗在药液中暴露时间的延长,LC50值逐渐减小。使它隆对草鱼、鲢鱼和鲫鱼的96h LC50值分别为0．4764、0．3962和0．6918mg·L^-1。使它隆对草鱼、鲢鱼和鲫鱼的安全浓度分别为0．0476、0．0392和0．0692mg·L^-1【结论与意义】使它隆对草鱼、鲢鱼和鲫鱼表现高毒,这为使它隆的风险评估和环境安全管理提供了依据。     

Sediment-Associated Phototoxicity to Aquatic Organisms

Phototoxicity is a two to greater than 1000-fold increase in chemical toxicity caused by ultraviolet radiation (UV), which has been demonstrated in a broad range of marine and freshwater fish, invertebrates, and other aquatic organisms in water column exposures. Field collected sediments containing polycyclic aromatic hydrocarbons (PAHs) and other contaminants are phototoxic to sediment-dwelling organisms in laboratory tests, but in situ or field investigations of phototoxicity have not been reported. Sediment provides a pathway for the bioaccumulation of phototoxic chemicals through contact with and ingestion of bedded and suspended sediment, and maternal transfer, but risks are uncertain. Risks from sediment-associated phototoxicity will be greatest in areas of both high contaminant exposure (e.g., surficial and suspended sediments in harbors, outfall areas, and spill sites), and high UV exposure (e.g., high optical clarity or shallow depths). Organisms and life-stages most at risk will be those translucent to UV that inhabit the photic zone and near shore areas, but benthic organisms may have generally low UV exposure because of life history and morphological characteristics. Site-specific assessments are needed to characterize risks both spatially and temporally because of heterogeneous sediment contamination and large differences in species sensitivity and exposure pathways.     

Physiological interactions of silver and humic substances in Daphnia magna: effects on reproduction and silver accumulation following an acute silver challenge

Silver (Ag) in aquatic environments mediates its toxic actions by inhibiting sodium influx. Humic substances protect against silver toxicity by complexing the toxic, ionic form of the metal, but may also directly stimulate sodium influx in aquatic organisms. This study investigated the effects of silver and humic substances on the water flea Daphnia magna. Acute silver challenge (24 h; 1 microg L(-1)) and the chronic exposure to humic substances (Aldrich humic acid; 7 mg C L(-1)) had considerable influence on daphnid physiology and reproduction. In particular silver exposure in the absence of humic substances stimulated reproduction, resulted in enhanced adult mass, and altered both the response of the animal to subsequent silver exposure and a physiological surrogate measure of silver toxicity (whole body sodium concentration). The presence of humic substances countered the effects on adult mass and reproduction, returning these parameters to control levels. Humic substances also lowered silver body burden, but with significantly improved whole body sodium status than previously silver-exposed animals. These changes may distort the correlation between silver body burden and indicators of toxic action, an important tenet of site-specific risk assessment tools such as the biotic ligand model.     

The influence of algal densities on the toxicity of chromium for Ceriodaphnia dubia Richard (Cladocera, Crustacea)

Food availability may affect metal toxicity for aquatic organisms. In the present study, the influence of high, medium and low densities of the algae Pseudokirchneriella subcapitata (10(6), 10(5) and 10(4) cells.mL(-1), respectively) on the chronic toxicity of chromium to the cladoceran Ceriodaphnia dubia was investigated. C. dubia was exposed to a range of chromium concentration from 2.71 to 34.04 microg.L(-1) and fed with algae at various densities. In another experiment, the green alga was exposed to chromium concentrations (94 to 774 microg.L(-1)) and supplied as food in different densities to zooplankton. The survival and reproduction of the cladoceran were measured in these toxicity tests. The IC50 for Cr to P. subcapitata and metal accumulated by algal cells were determined. The results of a bifactorial analysis (metal versus algal densities) showed that metal toxicity to zooplankton was dependent on algal densities. Significant toxic effects on the reproduction and survival of C. dubia were observed at 8.73, 18.22 and 34.04 microg.L(-1) Cr when the test organisms were fed with 10(6) cells.mL(-1) of P. subcapitata. Although the chlorophyta retain low chromium content, a decrease in the reproduction and survival of C. dubia occurred when they were fed with high algal density contaminated with 774 microg.L(-1) Cr. It was concluded that high algal density have an appreciable influence on chromium toxicity to daphnids.     

Invited Debate/Commentary: Selenium — A Potential Time Bomb or Just Another Contaminant?

Environmental issues related to selenium are complex and not universally understood. This paper provides detailed information regarding selenium and associated aquatic environmental issues, and then introduces and comments on five debate/commentary papers discussing selenium in the context of the title of this paper. Selenium has a complex and not fully understood biogeochemistry in the aquatic environment as well as an unusual mode of toxicity (acute via water column exposure; chronic via food chain exposure). It has the narrowest range between nutritional requirements and toxicity of any essential element, and chronic toxicity is not readily predictable. Selenium contamination of waters or even of tissues does not necessarily indicate a ticking time bomb; there are no generally accepted or universally accepted threshold values for chronic toxicity. Assessing risk must be done site-specifically in a risk assessment framework, focusing on reproductive effects to sensitive exposed fish and waterfowl and on “worst case” hydrologic units. Unless selenium inputs decrease or site-specific biogeochemistry can be shown not to change, continued biological monitoring and testing are required. Provided the necessary investigative and monitoring studies are done, any potential selenium time bombs can be defused.     

Complex interactions among a nematode parasite (Daubaylia potomaca), a commensalistic annelid (Chaetogaster limnaei limnaei), and trematode parasites in a snail host (Helisoma anceps)

Many biotic interactions can affect the prevalence and intensity of parasite infections in aquatic snails. Historically, these studies have centered on interactions between trematode parasites or between trematodes and other organisms. The present investigation focuses on the nematode parasite Daubaylia potomaca and its interactions with a commensal, Chaetogaster limnaei limnaei , and a variety of trematode species. It was found that the presence of C. l. limnaei indirectly increased the mean intensity of D. potomaca infections, apparently by acting as a restraint for various trematode parasites, particularly the rediae of Echinostoma sp. In turn, Echinostoma sp. rediae adversely affected the mean intensity of D. potomaca by their consumption of both juvenile and adult nematodes present in tissues of the snail. These organisms not only belong to 3 different phyla but occupy distinct trophic levels as well. The complex interactions among these 3 organisms in the snail host provide an excellent example of biotic interactions influencing the infection dynamics of parasites in aquatic snails.     

Potential use of Lemna minor for the phytoremediation of isoproturon and glyphosate

Pesticides are being detected in water bodies on an increasingly frequent basis. The present study focused on toxicity and phytoremediation potential of aquatic plants to remove phytosanitary products from contaminated water. We investigated the capacity of Lemna minor (L. minor) to eliminate two herbicides isoproturon and glyphosate from their medium. Since phytoremediation relies on healthy plants, pesticide toxicity was evaluated by exposing plants to 5 concentrations (0-20 microg L(-1) for isoproturon and 0-120 microg L(-1) for glyphosate) in culture media for 4 d using growth rate and chlorophyll a fluorescence as endpoints. At exposure concentrations of 10 microg x L(-1) for isoproturon and 80 microg x L(-1) for glyphosate, effects on growth rate and chlorophyll fluorescence were minor (< 25%), so that this initial concentration was selected to study herbicide removal After a 4-d incubation, removal yields were 25% and 8% for isoproturon and glyphosate, respectively.     

Bio‐safety evaluation of Cry1Ac,Cry2Ab,Cry1Ca,Cry1F and Vip3Aa on Harmonia axyridis larvae

Dietary exposure studies are initial steps in environmental risk assessments of genetically engineered plants on non‐target organisms. These studies are conducted in the laboratory where surrogate species are exposed to purified and biologically active insecticidal compounds at higher concentrations than those expected to occur in transgenic crops foliage. Thus, dietary exposure (early tier) tests provide robust data needed to make general conclusions about the susceptibility of the surrogate species to the test substance. For this, we developed suitable artificial diet and used it to establish a dietary exposure test for assessing the toxicity of midgut‐active insecticidal compounds to the larvae of the Asian ladybird beetle Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae). Using boric acid as a model compound, we validated the bioassay established for H. axyridis larvae. An artificial diet containing boric acid which negatively affected survival, development and adult weights was offered to larvae and indicated that the bioassay was able to detect toxic effects of insecticidal substances incorporated in diets. Using this dietary exposure test, environmental risk assessment of Cry1Ac, Cry2Ab, Cry1Ca, Cry1F and the non‐Cry protein Vip3Aa was evaluated by analysing pupation rates, adult emergence rates, 7‐day larval weights, and freshly emerged male and female weights among the toxin treatments and a pure artificial diet. These life‐table parameters did not vary among artificial diets containing 200 μg/g Bt proteins or pure artificial diet. In contrast, boric acid adversely affected all life‐table parameters. Thus on these bases, we concluded H. axyridis larvae are not sensitive to these Bt proteins expressed in genetically engineered crops.     

Potential Importance of Inhalation Exposures for Wildlife Using Screening-Level Ecological Risk Assessment

Ecological risk assessments (ERAs) have largely ignored exposure to wildlife via inhalation on the assumption that it is negligible compared to the ingestion route of exposure. The assessment of inhalation risk also has been limited due to a paucity of relevant ecotoxicity data. This article presents toxicity reference values (TRVs) for small mammals based on chronic or subchronic exposure studies for a range of organic and trace metal contaminants and ecologically relevant inhalation endpoints. Potential risk to small mammals due to ingestion and inhalation exposure were compared in two hypothetical air emission scenarios for a point source (incinerator) and non-point source emissions (vehicular emissions). Using two screening-level ERAs, we conclude that it may now be time to reconsider inhalation risk to wildlife in the case of atmospheric emissions of some metals and volatile organic compounds (VOCs). In the case of birds, the toxicological database remains too small to assess risks via this pathway. However, for mammals, we suggest that inhalation exposures to contaminants such as cadmium, benzene, and other VOCs could be important.     

Qualitative detection of the NSAIDs diclofenac and ibuprofen in the hair of Eurasian otters (Lutra lutra) occupying UK waterways with GC�CMS

The pervasiveness of pharmaceuticals such as nonsteroidal anti-inflammatory drugs (NSAIDs) in the aquatic ecosystem through the discharge of wastewater, and their potential to biomagnify within this ecosystem, is now recognised. Residues of diclofenac and ibuprofen are currently being detected in surface waters and aquatic organisms throughout the UK and Europe. However, the levels of these residues in fish and other aquatic organisms, particularly lower trophic level prey species, have not yet been determined. While exposure to diclofenac is known to adversely affect fish, the degree to which other aquatic organisms are exposed and impacted through continuous ingestion of contaminated prey and interaction with the aquatic habitat remains unknown. The extent and effects of exposure to ibuprofen also remain largely unknown. As an exploratory subset of a broader study to investigate the detectability of diclofenac in alternative biological matrices, we analysed hair samples from Eurasian otters (Lutra lutra, n?=?28) for residues of the two NSAIDs using GC?CMS. The otters were collected from six counties in England as part of an ongoing otter health monitoring project at the Wildlife Veterinary Investigation Centre in Chacewater, UK. Diclofenac was qualitatively detected in five hair wash and 15 extract samples, and ibuprofen was determined to be present in at least two of the hair extract samples. Here, we provide preliminary evidence that otters are exposed to both NSAIDs and argue for further studies to identify residue loads in the otters and their prey to fully assess the pervasiveness of these compounds and potential risks of ongoing exposure to them.     

Developmental and neurobehavioural toxicity study of arsenic on rats following gestational exposure

To characterize developmental and behavioral alterations induced by arsenic exposure, Albino rats were exposed to arsenic (0, 1.5, 3.0 and 4.5 mg/kg/day/po) from gestation day 8 to till parturition and the offspring were observed over the first 3 postnatal weeks, until they were weaned on post-natal day (PND) 21. Once the pups were delivered (PND0), the treatment was discontinued. All pups were assessed for physical development, reflex development, strength and motor coordination from standard neurobehavioural developmental test batteries beginning on PND1. Gestational administration of arsenic at tested dose levels, showed no significant changes in the day of appearance of eye opening, startle reflex, negative geotaxis and spontaneous alteration performance in comparison to the control group. The number of live fetuses, mean fetal body weight and percentages of resorptions or malformations per litter were not affected by arsenic exposure. No treatment-related malformations or developmental variations were noted at any exposure level, suggesting that arsenic exposure at this dose level did not adversely affect behavioural endpoints of developmental toxicity.     

Photosynthetic and biochemical responses of the freshwater green algae <Emphasis Type="Italic">Closterium ehrenbergii</Emphasis> Meneghini (Conjugatophyceae) exposed to the metal coppers and its implication for toxicity testing

The freshwater green algae Closterium is sensitive to water quality, and hence has been suggested as ideal organisms for toxicity testing. In the present study, we evaluated the photosynthetic and biochemical responses of C. ehrenbergii to the common contaminants, coppers. The 72 h median effective concentrations (EC₅₀) of CuSO₄ and CuCl₂ on the test organism were calculated to be 0.202 mg/L and 0.245 mg/L, respectively. Exposure to both coppers considerably decreased pigment levels and photosynthetic efficiency, while inducing the generation of reactive oxygen species (ROS) in cells with increased exposure time. Moreover, the coppers significantly increased the levels of lipid peroxidation and superoxide dismutase (SOD) activity, even at relatively lower concentrations. These suggest that copper contaminants may exert deleterious effects on the photosynthesis and cellular oxidative stress of C. ehrenbergii, representing its powerful potential in aquatic toxicity assessments.