Ecotoxicological study of arsenic and lead contaminated soils in former orchards at the Hanford site,USA

The purpose of this study was to assess ecotoxicity of former orchard soils contaminated with lead arsenate pesticides at the Hanford Site in Washington state (USA). Surface soil, plant, and invertebrate samples were collected from 11 sites in former orchard areas. Mean (standard deviation [SD]) for As and Pb in soil were 39.5 (40.6) and 208 (142) mg/kg dry wt, respectively (n = 11). These concentrations exceeded Hanford background levels but were similar to orchard soils elsewhere. In our study, As and Pb soil concentrations were positively and significantly correlated (r = 0.87, Bonferroni P < 0.05). Speciation of total inorganic As in soil (n = 6) demonstrated that As+5 was the dominant form (>99%). Mean (SD) for As and Pb in cheatgrass were 3.9 (7.9) and 12.4 (20.0) mg/kg dry wt, respectively (n = 11), while mean (SD) for As and Pb in darkling beetles were 5.4 (2.6) and 3.9 (3.0) mg/kg dry wt, respectively (n = 8). Linear regressions were constructed to estimate soil to cheatgrass and soil to darkling beetle uptake for As and Pb. These were significant (Bonferroni P < 0.05) only for cheatgrass versus soil (As) and darkling beetle versus soil (Pb). Standardized lettuce seedling and earthworm bioassays were performed with a subset of soil samples (n = 6). No significant effects (P > 0.05) were observed in lettuce survival or growth nor in earthworm survival or sublethal effects. Based on these bioassays, unbounded no observed effect concentrations (NOECs) in soil for As and Pb were 128 and 390 mg/kg dry wt, respectively. However, our range of soil concentrations generally overlapped a set of ecotoxicological benchmarks reported in the literature. Given uncertainty and limited sampling related to our NOECs, as well as uncertainty in generic benchmarks from the literature, further study is needed to refine characterization of As and Pb ecotoxicity in former orchard soils at the Hanford Site. © 2011 Wiley Periodicals, Inc. Environ Toxicol 29: 10–20, 2014.     

A subchronic in situ exposure method for evaluating effects in small‐bodied fish at contaminated sites

In situ fish‐caging studies at contaminated sites can provide information that is more realistic compared to traditional laboratory‐based studies. However, few methods have been developed for exposing sentinel fish species for subchronic durations, and fewer still are optimized for exposing small‐bodied fish while maintaining fish health and growth throughout the caging trial. Those methods typically lack a feeding regimen during the fish caging trial. While that may be acceptable or even appropriate for typical short‐term toxicity testing, it does limit the duration of the exposure, and may not be suitable when post‐caging trials or observations are necessary. Returning healthy fish to the lab following the in situ exposure would be important, for example, in studies designed to examine long‐term or multigenerational effects following an in situ exposure. In this article we describe a subchronic method for caging small fish at contaminated sites while maintaining growth and reproductive development. Fathead minnow (Pimephales promelas) were caged in situ for 6 weeks, after which time they were returned to the lab where they were evaluated for health and reproductive performance. Growth and reproductive endpoints revealed no adverse effect on fish due to fish caging and related handling, demonstrating the suitability of our caging and feeding method for long‐term caging studies. © 2011 Wiley Periodicals, Inc. Environ Toxicol 29: 54–63, 2014.     

Immunological and physiological effects of chronic exposure of Peromyscus leucopus to Aroclor 1254 at a concentration similar to that found at contaminated sites

Polychlorinated biphenyls (PCBs) are environmental contaminants known to cause adverse health effects to biological systems. Limited data are available on their effects on the immune system of wildlife species. Previously, we found that 4 and 6-week-old white-footed mice (Peromyscus leucopus) born from dams injected with a single dose (300 mg/kg) of Aroclor 1254, had altered immunological, hematological, and biochemical responses. Here, we examined the effect of transplacental, lactational and postnatal exposure to Aroclor 1254, at a concentration similar to that found at contaminated sites, on various physiological parameters of 22-week-old white-footed mice. Liver weight and liver somatic index of PCB treated animals were significantly higher, the combined weights of the adrenal glands were significantly lower and EROD and BROD enzyme activity was significantly higher compared to control values. The number of thymocytes of the treated mice was significantly lower than that of the controls; however, thymocytes of treated mice had a higher proliferative response to the mitogen Con A. These alterations were correlated with the PCBs body burdens. Some toxic effects of chronic exposure to PCBs, at levels comparable to exposure found in contaminated sites in the USA, are still evident in adult P. leucopus.     

Ecotoxicological evaluation of contaminated soil using the legume root nodule symbiosis as effect parameter

The legume root nodules are the site of biological nitrogen fixation in the legume—rhizobium symbiosis. They are a structure unique to this symbiosis and morphologically as well as physiologically distinct from other plant organs. We will present evidence that the formation of nodules (nodulation) may serve for ecotoxicological evaluation of contaminated soil. Substances affecting the macro- and/or microsymbionts vitality, such as certain heavy metals or polycyclic aromatic hydrocarbons (PAHs), reduce nodulation before visible damage of the plant occurs. Tests were performed in petri dishes that were planted with alfalfa seedlings and inoculated with Rhizobium meliloti. Mineral agar served as substrate. Test substances were added to the mineral agar before pouring it into petri dishes (application of heavy metals), or were sprayed as etheral solutions onto the surface of solidified medium (application of PAHs). For investigation of contaminated soil, the soil material was first mixed with mineral agar and then poured into petri dishes. Appropriate controls were made by extracting an aliquot of soil with methylene chloride to remove hazardous substances. Data from stressed plants were taken after 15 days of cultivation on contaminated substrate. A dose-responsive decrease in nodulation was found after application of CdCl₂, NaAsO₂, fluoranthene, and other PAHs. PAH-contaminated soil (75 mg/kg) caused only a slight reduction in nodulation of alfalfa. But when PAHs were extracted and restored into the extracted soil material, toxicity and uptake of PAHs into roots and shoots dramatically increased. Toxicity and uptake of PAHs were also enhanced by reducing the amount of humic matter added to the test system. © by John Wiley & Sons, Inc.     

Assessment methods for concerns about contaminated sites

The management and protection of environmental resources from anthropogenic stressors require public support. Understanding the concerns of the public with respect to environmental problems allows policymakers and managers to make wise decisions. In this study, three methods of assessing public concerns about Brookhaven National Laboratory, a Department of Energy facility on Long Island, NY, were compared using (1) an open-ended question about concerns, (2) a rating of a list of concerns, and (3) a ranking of the highest and lowest concern from a list provided. The greatest global and local concerns (as expressed as an open-ended question) were pollution and environmental health, while the greatest concerns about Brookhaven National Laboratory (BNL) also included human health. Accidents, loss of public and ecological health, and nuclear material were rated the highest concerns on a rating scale. However, when asked to pick out the most important issue about BNL from a list, protecting human health and protecting ecology were the problems of most concern; protecting economic interests was rated the lowest. The three methods gave congruent results. No new concerns of major significance turned up on the open-ended question, suggesting that if a method is inclusive, a list of concerns can be given to stakeholders for quantitative analysis of public perceptions. Understanding of public concerns is critical to making sound management decisions, and this article contributes to our understanding of how to evaluate concerns about contaminated sites, particularly in urban areas.     

Applying whole water samples to cell bioassays for detecting dioxin-like compounds at contaminated sites

Methodology was developed in order to rapidly and cost-efficiently screen whole water samples without extraction for the presence of dioxin-like compounds using a cell bioassay approach. Presence of dioxin-like compounds was indicated by the induction in the rainbow trout (Oncorhynchus mykiss) liver cell line, RTL-W1, of cytochrome CYP1A, which was measured as 7-ethoxyresorufin-O-deethylase (EROD) activity. Two simple culture media, L-15/ex and Earle's-G, prepared in tissue culture water and supplemented with 5% serum, proved suitable for supporting RTL-W1 cell viability and induction of EROD activity by the model inducers, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and benzo[a]pyrene (BaP). Preparation of the same simplified media using whole surface and ground water instead of tissue culture water again allowed EROD induction by spiked TCDD and BaP to be detected but higher concentrations of inducers were necessary. Despite this reduced sensitivity, RTL-W1 cells responded to 4 out of 40 ground water samples from a former oil and lignite processing site with significant EROD induction. In the future, the value of the bioassay is as an inexpensive means of quickly screening ground and surface water samples to identify high contaminant levels particularly at industrial sites, where detailed site-investigations and long-term monitoring programs are required.     

Ecotoxicological effects of selected cyanobacterial secondary metabolites: a short review

Cyanobacteria are one of the most diverse groups of gram-negative photosynthetic prokaryotes. Many of them are able to produce a wide range of toxic secondary metabolites. These cyanobacterial toxins can be classified in five different groups: hepatotoxins, neurotoxins, cytotoxins, dermatotoxins, and irritant toxins (lipopolysaccharides). Cyanobacterial blooms are hazardous due to this production of secondary metabolites and endotoxins, which could be toxic to animals and plants. Many of the freshwater cyanobacterial blooms include species of the toxigenic genera Microcystis, Anabaena, or Plankthotrix. These compounds differ in mechanisms of uptake, affected organs, and molecular mode of action. In this review, the main focus is the aquatic environment and the effects of these toxins to the organisms living there. Some basic toxic mechanisms will be discussed in comparison to the mammalian system.     

Atrazine contaminated sites and bullfrog tadpoles: evasive trends and biochemical consequences

Atrazine (ATZ) is one of the most used active principles in agricultural systems. This pesticide has the ability to easily accumulate in terrestrial and aquatic environments, causing impacts with chronic adverse effects. Avoidance tests are tests that seek to assess the concentration from which a given organism escapes, that is, migrates to another habitat. They are being used as a modality of innovative and minimally invasive ecotoxicological tests. Our objective was to evaluate the sensitivity and possible toxic effects of ATZ in bullfrog tadpoles (Lithobates catesbeianus), through avoidance tests and oxidative stress analyses. We performed the behavioral avoidance test lasting 12 h, with observations every 60 min in a linear multi-compartment system with seven compartments. Each compartment corresponded to a concentration: negative control, 1, 2, 20, 200, 2000, 20,000 µg L⁻¹. After the selection of habitat, organisms were forcedly maintained in the chosen concentrations for 48 h and then, metabolic effects were measured assessing the blood plasma amino acid profile and liver protein degradation. We also determined the effective concentrations of ATZ tested at 0 h and 48 h. The results showed that there was an effect of the treatment on the distribution of tadpoles, but not on the hours or on the combined effect (interaction). The biochemical analyses also showed a concentration-dependent relationship which caused significant toxic effects even in a short period of time. In conclusion, these frogs were able to avoid places with high concentrations of ATZ in the first hours of exposure, which suggests that in the natural environment these animals can migrate or avoid areas contaminated by this herbicide; however, depending on the selected concentration, serious biochemical consequences can occur.

     

A novel "by difference" method for assessing dermal absorption of polycyclic aromatic hydrocarbons from soil at federal contaminated sites

A highly precautionary cost-effective method for estimating dermal absorption using data from 24-h skin soap washes from in vitro dermal absorption tests in Bronaugh flow-through diffusion cells with human skin is reported. Skin was dosed with 16 U.S. Environmental Protection (EPA) priority polycyclic aromatic hydrocarbons (PAH) applied in mixture each at 2 μg/ml (ppm) in acetone without soil. Concurrent tests were conducted with an unspiked aqueous suspension of PAH-contaminated soil obtained from a Canadian federal contaminated site. Percentage dermal absorption was estimated "by difference" from the applied dose and that detected by high-performance liquid chromatography (HPLC) in 24-h skin soap washes. The dermal absorption for 11 PAH ranged from 71 to 88.3% without and with soil, respectively. Lower absorption was found for 5 PAH in soil, in the range of 26.4 to 60.8%. Data could not be corrected for evaporative loss due to inconsistent data from Tenax adsorbent. Corroboratory gas chromatography/mass spectroscopy (GC/MS) tests are needed. Previously published in vitro data from the authors' laboratory supported use of the "by difference" method.     

Ecotoxicological effects of human and veterinary antibiotics on water flea (Daphnia magna)

In the present study, we assessed the ecotoxicological effects of selected human and veterinary antibiotics to D. magna. Ecological risk assessment was done by calculating the risk quotients (RQs) of the antibiotics to the species. Results showed that enrofloxacin, a veterinary fluoroquinolone antibiotic, was the most toxic against D. magna with a 48 h EC₅₀ value of 28.59 mg/l. The binary mixture of fluoroquinolones was also more toxic to the species than binary mixtures of macrolides. Fecundity in organisms in negative control was higher than fecundity in organisms exposed to environmentally relevant concentrations of the four antibiotics. Enrofloxacin also has a moderate risk to the species with RQ values of 0.199 and 0.416 in surface waters and wastewaters, respectively. Antibiotics pose a greater ecological risk when present in mixtures in the aquatic environment. Environmental standards for pharmaceuticals should incorporate mixture toxicity data to ensure accurate protection of non-target organisms in polluted environments.     

Sodium phenobarbitone reverses the anxiogenic effects of compounds acting at three different central sites

Sodium phenobarbitone was tested for its ability to antagonise the anxiogenic effects of compounds acting at three different central sites. These compounds were: FG 7142, a beta-carboline which acts at the benzodiazepine binding site on the GABA-benzodiazepine receptor complex; pentylenetetrazole, which acts at the picrotoxinin site on the GABA-benzodiazepine receptor complex; and yohimbine which is an antagonist at the alpha 2-adrenoceptor. The experiments were carried out in two tests of anxiety using rats. In the social interaction test (the test arena was familiar and dimly lit), FG 7142 (5 mg/kg) and pentylenetetrazole (15 mg/kg) reduced the time spent in social interaction (indicating anxiogenic activity); these effects were reversed by sodium phenobarbitone (35 mg/kg). Sodium phenobarbitone (35 mg/kg) alone decreased locomotor activity as measured in the social interaction test, which was reversed by pentylenetetrazole (15 mg/kg). In the elevated plus-maze, FG 7142 (6.7 mg/kg) pentylenetetrazole (20 mg/kg) and yohimbine (4 mg/kg) reduced the percentage of open-arm entries and the percentage of time spent on the open arms (indicating anxiogenic activity); these effects were reversed by sodium phenobarbitone (35 mg/kg). Sodium phenobarbitone (35 mg/kg) alone significantly increased the percentage of open-arm entries and the percentage of time spent on the open arms (indicating anxiolytic activity). This study, together with previous studies using other clinically-effective anxiolytic drugs, suggests that the ability of a compound to antagonise the effects of anxiogenic agents may be a useful indirect means of predicting anxiolytic activity.     

U50,488H differentially antagonizes the bladder effects of mu agonists at spinal sites

The mu antagonist property of the kappa agonist U50,488H was studied at the spinal level, using motility of the rat urinary bladder as an endpoint in vivo. Intrathecal (i.th.) administration of the mu agonists [D-Ala2,NMePhe4,Gly-ol]enkephalin (DAGO), [N-MePhe3,D-Pro4]enkephalin (PL017), morphine and normorphine, as well as the delta agonist [D-Pen2,D-Pen5]enkephalin (DPDPE), resulted in an equieffective inhibition of volume-initiated contractions of the urinary bladder. In contrast, i.th. administration of U50,488H, a highly selective kappa agonist, had no effect on bladder motility. Pretreatment of rats with i.th. U50,488H prior to agonist administration, blocked the suppression of spontaneous bladder activity induced by equieffective i.th. does of morphine and normorphine, but failed to alter the inhibitory effect of the mu agonists DAGO and PL017, or that of the delta agonist DPDPE. The finding that U50,488H differentially antagonized the identical bladder effects of several mu agonists suggests the presence of mu receptor subtypes (mu isoreceptors) in the rat spinal cord, which may be involved in the regulation of bladder function.     

Ecotoxicological effects of creosote contamination on benthic microbial populations in an estuarine environment†

Ecotoxicological effects of creosote contamination on benthic bacterial communities in the Elizabeth River, Virginia were investigated using both structural and functional microbial parameters. Parameters included direct counts, viable counts of heterotrophs and “cresol-utilizers”, and bacterial production determined using the tritiated thymidine uptake method. Ancillary data included temperature, salinity, Eh profiles, concentrations of polycyclic aromatic hydrocarbons (PAHs), sediment granulometry and total organic carbon. Two reference stations in relatively nonpolluted areas were sampled for comparative data. Results indicated that cell specific and total heterotrophic bacterial production were depressed in a dose-dependent manner with increasing sediment PAH concentrations. Sediment properties and seasonal changes in temperature appeared to modify the effects of PAHs on bacterial production. Direct bacterial counts and viable counts of total heterotrophs were depressed in the most contaminated sediments. Evidence of creosote adaptation was equivocal, with cresol-utilizer densities not significantly elevated at contaminated stations. The presence of creosote was associated with shifts of Eh toward more negative values compared to nonpolluted sediments. Toxicants which reduce benthic bacterial production may indirectly impact other trophic groups through aberrant cycling of carbon or nutrients. Of the parameters examined, the tritiated thymidine production assay was found to be the most sensitive for detection of ecotoxicological effects.     

Ecotoxicological effects of jute retting on the survival of two freshwater fish and two invertebrates

Severe deterioration of water quality occurs during jute retting in ponds, canals, floodplain lakes, and other inland water bodies in the rural areas of West Bengal in India. Attempts were made to evaluate changes in the physicochemical parameters of water caused by jute retting, and their impact on the survival of two species of freshwater fish (Labeo rohita and Hypophthalmicthys molitrix) and two species of freshwater invertebrate (Daphnia magna, a Cladocera, and Branchiura sowerbyi, an Oligochaeta). Results showed that jute retting in a pond for 30 days resulted in a sharp increase in the BOD (>1,000 times) and COD (>25 times) of the water, along with a sharp decrease in dissolved oxygen (DO). Free CO₂, total ammonia, and nitrate nitrogen also increased (three to five times) in water as a result of jute retting. Ninety-six-hour static bioassays performed in the laboratory with different dilutions of jute-retting water (JRW) revealed that D. magna and B. sowerbyi were not susceptible to even the raw JRW whereas fingerlings of both species of fish were highly susceptible, L. rohita being more sensitive (96 h LC₅₀ 37.55% JRW) than H. molitrix (96 h LC₅₀ 57.54% JRW). Mortality of fish was significantly correlated with the percentage of JRW.     

An evaluation of contaminated estuarine sites using sediment quality guidelines and ecological assessment methodologies

Toxic contaminants may enter estuarine ecosystems through a variety of pathways. When sediment contaminant levels become sufficiently high, they may impact resident biota. One approach to predict sediment-associated toxicity in estuarine ecosystems involves the use of sediment quality guidelines (ERMs, ERLs) and site-specific contaminant chemistry while a second approach utilizes site-specific ecological sampling to assess impacts at the population or community level. The goal of this study was to utilize an integrated approach including chemical contaminant analysis, sediment quality guidelines and grass shrimp population monitoring to evaluate the impact of contaminants from industrial sources. Three impacted sites and one reference site were selected for study. Grass shrimp populations were sampled using a push-netting approach. Sediment samples were collected at each site and analyzed for metals, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and pesticides. Contaminant levels were then compared to sediment quality guidelines. In general, grass shrimp population densities at the sites decreased as the ERM quotients increased. Grass shrimp densities were significantly reduced at the impacted site that had an ERM exceedance for chromium and the highest Mean ERM quotient. Regression analysis indicated that sediment chromium concentrations were negatively correlated with grass shrimp density. Grass shrimp size was reduced at two sites with intermediate levels of contamination. These findings support the use of both sediment quality guidelines and site-specific population monitoring to evaluate the impacts of sediment-associated contaminants in estuarine systems.     

Ecotoxicological effects of bisphenol A and nonylphenol on the freshwater cladocerans Ceriodaphnia silvestrii and Daphnia similis

Toxicities of bisphenol A (BPA) and nonylphenol (NP) to the neotropical freshwater cladocerans Ceriodaphnia silvestrii and Daphnia similis were studied under laboratory conditions. Acute exposures to BPA generated mean 48-h EC₅₀ values of 14.44 (6.02–22.85) mg L^?1 for C. silvestrii and 12.05 (1.73–22.37) mg L^?1 for D. similis. When the organisms were exposed to acute doses of NP, mean 48-h EC₅₀ values were 0.055 (0.047–0.064) mg L^?1 (C. silvestrii) and 0.133 (0.067–0.200) mg L^?1 (D. similis). Ceriodaphnia silvestrii was also tested in chronic bioassays, which resulted in mean 8-d IC₂₅ values of 2.43 (2.16–2.69) mg L^?1 BPA [no observed effect concentration (NOEC): 1.38?mg L^?1] and 0.020 (0.015–0.026) mg L^?1 NP (NOEC: 0.015?mg L^?1). These laboratory tests are valuable to broaden the understanding of the environmental threat posed by BPA and NP in aquatic ecosystems, and to increase the knowledge about the sensitivity of neotropical indigenous species to these contaminants. In addition to the laboratory bioassays, species sensitivity distributions were used to suggest protective concentrations of BPA and NP to prevent adverse effects on freshwater organisms. According to the obtained results, concentrations lower than 36.47?µg L^?1 BPA and 1.39?µg L^?1 NP are not expected to adversely impact aquatic organisms in natural ecosystems.     

Histamine releasing peptide (HRP) has proinflammatory effects and is present at sites of inflammation

Albumin, the most abundant plasma protein, readily enters sites of inflammation during the period of increased vascular permeability. There it encounters proteases released from mast cells and invading leukocytes which earlier work has shown can act on albumin to liberate the peptide, histamine releasing peptide (HRP), first identified and named by its ability to stimulate histamine release from isolated mast cells. In this report we show that HRP releases histamine from cutaneous mast cells in vivo resulting in increased vascular permeability and persistent edema while in vitro, HRP promotes chemotaxis of leukocytes and enhances macrophage phagocytosis. Moreover, we show that the level of HRP is increased with the induction of an acute cutaneous inflammatory response in rats, that HRP is present at sites of acute and chronic inflammation in humans and that HRP is rapidly degraded by proteases thereby limiting its action to the area of its generation. We suggest that HRP is a pro-inflammatory peptide that helps amplify and perpetuate the inflammatory response. Inhibitors of inflammatory proteases or antagonists that block the action of peptides like HRP may, therefore, be useful in breaking the cycle of inflammation.     

Stimulation of defense factors for oysters deployed to contaminated sites in Pensacola Bay,Florida

A positive association between chemical contaminants and defense factors has been established for eastern oysters (Crassostrea virginica) from Florida, but it is unknown whether such factors can be stimulated through short-term exposure to contaminants in the field. Hatchery oysters were deployed at two contaminated sites and one reference site near Pensacola, Florida, during spring and summer in 1998. Putative defense measurements, notably hemocyte count and bactericidal activity, were significantly elevated after 12-week deployment during summer at the most contaminated site. This site exhibited a dramatic increase in chemical concentrations in oyster tissue relative to both the initial concentrations in hatchery oysters and to oysters deployed at the reference site. Hemocyte activity was not stimulated after 16-week deployment of hatchery oysters in spring, despite similar increases in tissue chemical concentrations, so defense activation by short-term exposure may covary with other unmeasured environmental or physiological parameters. Using the converse approach, Pensacola Bay oysters were collected from two contaminated sites and deployed at the reference site for 16 weeks during spring. Results from this converse deployment were ambiguous; serum lysozyme concentrations were reduced for oysters transplanted from both sites, but hemocyte activities were not significantly changed. The principal outcome from this study was the demonstration of enhanced defense activities for oysters upon short-term summer deployment at a contaminated site.     

Ecotoxicological evaluation of the antimalarial drug chloroquine

There is limited information available about the potential environmental effects of chloroquine (CQ), a widely used antimalarial agent and a promising inexpensive drug in the management of HIV disease. The acute effects of CQ were studied using four ecotoxicological model systems. The most sensitive bioindicator was the immobilization of the cladoceran Daphnia magna, with an EC50 of 12 microM CQ at 72 h and a non-observed adverse effect level of 2.5 microM CQ, followed very closely by the decrease of the uptake of neutral red and the reduction of the lysosomal function in the fish cell line PLHC-1 derived from the top minnow Poeciliopsis lucida, probably due to the selective accumulation of the drug into the lysosomes. There was significant cellular stress as indicated by the increases on metallothionein and glucose-6P dehydrogenase levels after 24 h of exposure and succinate dehydrogenase activity mainly after 48 h. No changes were observed for ethoxyresorufin-O-deethylase (EROD) activity. The least sensitive model was the inhibition of bioluminescence in the bacterium Vibrio fischeri. An increase of more than five-fold in the toxicity from 24 to 72 h of exposure was observed for the inhibition of the growth in the alga Chlorella vulgaris and the content of total protein and MTS tetrazolium salt metabolization in PLHC-1 cells. At the morphological level, the most evident alterations in PLHC-1 cultures were hydropic degeneration from 25 microM CQ after 24h of exposure and the presence of many cells with pyknotic nuclei, condensed cytoplasm and apoptosis with concentrations higher than 50 microM CQ after 48 h of exposure. In conclusion, CQ should be classified as harmful to aquatic organisms.     

Ecotoxicological effects of alpha-cypermethrin on freshwater alga Chlorella sp.: Growth inhibition and oxidative stress studies

Alpha-cypermethrin (ACy) is a synthetic pyrethroid insecticide commonly used in agricultural practices for controlling a broad range of insect pests particularly belonging to the order Lepidoptera and Coleoptera. The present study aims to evaluate the toxic effect of ACy on microalgae by studying its influence on Chlorella sp. According to our knowledge, this is the first detailed study of ACy toxicity on microalgae. Significant growth inhibition of Chlorella sp. was observed at high ACy concentration (6−48 mg L⁻¹) during the entire 96 h bioassay. The 96 h median effective concentration (EC₅₀) of ACy was estimated to be 11.00 mg L⁻¹. Flow cytometry analysis showed an enhanced generation of reactive oxygen species (ROS) and intracellular lipid accumulation after 96 h exposure to 11.00 mg L^-1 of ACy. Further, the same ACy concentration showed a significant decrease in photosynthetic pigment content and an increase in antioxidant enzyme activity and malondialdehyde (MDA) content in Chlorella sp.