The impacts of bisphenol A (BPA) on abalone (Haliotis diversicolor supertexta) embryonic development

The effects of bisphenol A (BPA) on abalone (Haliotis diversicolor supertexta) embryonic development were investigated by exposing the fertilized eggs to four different concentrations of BPA (0.05, 0.2, 2 and 10 μg mL⁻¹). Toxicity endpoints including the embryo development parameters, the physiological features and the expression profile of several reference genes (prohormone convertase 1, PC1; cyclin B, CB; and cyclin-dependent kinase 1, CDK1) were assessed. The results showed that BPA could markedly reduce embryo hatchability, increase developmental malformation, and suppress the metamorphosis behavior of larvae. The possible toxicological mechanisms hidden behind of these effects (i.e. disturbing the embryogenesis) might result from three aspects: (1) BPA disturbance the cellular ionic homeostasis and osmoregulation of abalone embryos by changing the Na⁺-K⁺-ATPase and Ca²⁺-Mg²⁺-ATPase levels; (2) BPA induced oxidative damage of embryos by significantly alterating the peroxidase (POD) activities and the malondialdehyde (MDA) production; and (3) the RT-PCR analysis further demonstrated that BPA perturbed the cellular endocrine regulation and cell cycle progression by down-regulating the PC1 gene, as well as over-expressing the CB and CDK1 genes. This is the first comprehensive study on the developmental toxicity of BPA to the marine abalone at morphological, physiological and molecular levels. The results in this study also indicated that the embryo tests can contribute to the ecological risk assessment of the endocrine disruptors in marine environment.     

Photoenhanced toxicity of a weathered oil onCeriodaphnia dubia reproduction

Traditionally, the toxic effects of petroleum have been investigated by conducting studies in the absence of ultraviolet radiation (UV). Photomediated toxicity is often not considered, and the toxic effects of an oil spill can be grossly underestimated. The toxicity of a weathered oil collected from a monitoring well at an abandoned oil field toCeriodaphnia dubia was examined in the presence of UV. A solar simulator equipped with UVB, UVA, and cool white lamps was used to generate environmentally comparable solar radiation intensities.C. dubia were exposed to six concentrations of water accommodated fractions (WAF) of weathered oil in conjunction with three levels of laboratory simulated UV (Reference = < 0.002 μW/cm²UVB; 3.0 μW/cm² UVA; Low = 0.30 μW/cm² UVB; 75.0 μW/cm² UVA; High = 2.0 μW/cm² UVB; 340.0 μW/cm² UVA) and visible light. Seven day static renewal bioassays were used to characterize WAF/UV toxicity. WAF toxicity significantly (p < 0.05) increased when the organisms were exposed to WAF in the presence of UV. The photoenhanced toxicity of the WAF increased with WAF concentration within each UV regime. Relative to the reference light regime, the average number of neonates from adults exposed to 1.6 mg TPH/L decreased significantly by 20% within the low light regime, and by 60% within the high light regime. These results indicate that organisms exposed to dissolved-phase weathered oil in the presence of environmentally realistic solar radiation, exhibit 1.3–2.5 times greater sensitivity, relative to organisms exposed under traditional laboratory fluorescent lighting.     

Cypermethrin has the potential to induce hepatic oxidative stress, DNA damage and apoptosis in adult zebrafish (Danio rerio)

Cypermethrin (CYP), a widely used Type II pyrethroid pesticide, is one of the most common contaminants in the freshwater aquatic system. We studied the effects of CYP exposure on the induction of hepatic oxidative stress, DNA damage and the alteration of gene expression related to apoptosis in adult zebrafish. Hepatic mRNA levels for the genes encoding antioxidant proteins, such as Cu/Zn-Sod, Mn-Sod, Cat, and Gpx, were significantly upregulated when zebrafish were exposed to various concentrations of CYP for 4 or 8 days. In addition, the main genes related to fatty acid β-oxidation and the mitochondrial genes related to respiration and ATP synthesis were also significantly upregulated after exposure to high concentrations (1 and 3 μg L⁻¹) of CYP for 4 or 8 days. Moreover, in a comet assay of zebrafish hepatocytes, tail DNA, tail length, tail moment and Olive tail moment increased in a concentration-dependent manner. The significant induction (p < 0.01) of all four parameters observed with CYP concentrations of 0.3 μg L⁻¹ or higher suggests that heavy DNA damage was induced even at low levels. Furthermore, several apoptosis- related genes, such as p53, Apaf1 and Cas3, were significantly upregulated after CYP exposure, and Bcl2/Bax expression ratio decreased, especially in groups treated with 1 and 3 μg L⁻¹ CYP for 8 days. Taken together, our results suggested that CYP has the potential to induce hepatic oxidative stress, DNA damage and apoptosis in zebrafish. This information will be helpful in fully understanding the mechanism of aquatic toxicology induced by CYP in fish.     

Metallothionein induction, antioxidative responses, glycogen and growth changes in Tubifex tubifex (Oligochaete) exposed to the fungicide, fenhexamid

Laboratory studies were conducted to determine the effects of different concentrations of fenhexamid (0.1, 1, and 10 mg L(-1)) on growth, oxidative stress, protein, glycogen, and metallothionein (MT) contents in Tubifex tubifex after an exposure of 2, 4, and 7 days. In addition, residues of the fungicide were followed in water and in the worms. In water, fenhexamid concentration decreased slowly (maximum -2 +/- 0.03% after 2 days for 1 mg L(-1)). In the worms, it increased after 4 days and decreased thereafter, confirming that the worms were exposed to the fungicide and not to a degradation product. LC50 values were between 95.22 +/- 5.36 and 32.11 +/- 1.8 mg L(-1) depending on exposure time. Exposure to fenhexamid had a negative effect on T. tubifex growth (maximum effect -12.2 +/- 0.8% after 7 days with 10 mg L(-1)) demonstrating the toxic effect of the pesticide. This growth rate decrease was accompanied by a reduction in protein and glycogen contents. The activity of catalase (CAT), and glutathione reductase (GR) increased in response to the fungicide demonstrating an oxidative stress in the worms. In contrast glutathion-S-transferase activity (GST) decreased. Exposure to fenhexamid also induced synthesis of MT (maximum +78 +/- 8% after 2 days for 10 mg L(-1)). The specificity of MT concentration increase in response to metals is discussed.     

Effect of cement dust on the growth and yield of Brassica campestris L

Plants of Brassica campestris L. var. G-S20 were treated with cement dust, at rates of 3 (B(1)), 5 (B(2)) and 7 (B(3)) gm(-2) day(-1) for 90 days. Treated plants showed a consistent reduction in growth, photosynthetic pigments, yield and oil content over control plants. The overall phytomass of treated plants was significantly decreased, the maximum reduction being 64.8% in B(3) plants, followed by B(2) plants (55.3%) and B(1) plants (43.69%) at 60 days. The effect on oil content was also greatest in B(3) plants, where it was decreased by 6.13%.     

Cadmium stress alters gene expression of DNA mismatch repair related genes in Arabidopsis seedlings

Cadmium (Cd) is a non essential element, and is a widespread environmental pollutant. Exposure to Cd can result in a variety of adverse health effects in plant and humans. In the current study, Arabidopsis seedlings were used as a bio-indicator of Cd pollution. Seedlings were grown on MS media containing 0-6.0 mg L(-1) Cd for 18 days, and the gene expression patterns were used to link increased Cd exposure with progressive biological effects. Reduction of total soluble protein content in shoots of the Arabidopsis seedlings occurred with increase in Cd concentrations. For the gene expression patterns, seven genes known to be involved in cell division and DNA mismatch repair (MMR) system were investigated by semi-quantitative RT-PCR, and normalized using 18S rRNA gene expression. Expression of the proliferating cell nuclear antigen 2 (atPCNA 2), MutS 3 homolog (atMSH 3) and MutL1 homolog (atMLH1) genes in shoots of Arabidopsis was strongly induced by exposure to 0.75 mg L(-1) Cd, but were repressed by other Cd concentrations whereas exposure to 0.75-6 mg L(-1) of Cd resulted in a decreased expression of atPCNA1, atMSH 2, 6 and 7 genes independently of any observable biological effects, including survival, fresh weight and chlorophyll level of shoots. This work demonstrated that specific gene expression changes could serve as useful molecular biomarkers indicative of Cd exposure and related biological effects.     

UDS-test with freon 11 (R-11)

Trichlorofluoromethane, in concentrations of 80, 400, 2 000, 10 000 and 50 000 ppm, was administered to rats of both sexes (Sprague Dawley) by inhalation exposure. 2 000 ppm in air (= 11 200 mg/m³) amount to twice the MAK value of 1 000 ppm. At exposure times of 4 hours this corresponds to the MAK value defined for an 8 hour workday. Unscheduled DNA synthesis (UDS) was measured in single-cell suspensions of hepatocytes, pulmonary epithelial cells and lymphocytes of the spleen, respectively. In the pulmonary cells concentrations of 2 000, 10 000 and 50 000 ppm of freon 11 lead to a significantly increased mean silver grain count compared to a negative control group. In spleen and liver cells increasing concentrations of R 11 tend to increase the incorporation of thymidine into the DNA of the cells. These changes of the extent of unscheduled DNA synthesis can, however, not be statistically verified.     

Chronic effects of Cd on reproduction of Polypedilum nubifer (Chironomidae) through water and food

Chronic effects of Cd on reproduction of Polypedilum nubifer (Chironomidae) were investigated by Cd-exposure from the egg stage using a flow-through aquarium. No significant effect of Cd on reproduction was observed in the midge larvae which had been exposed to 10 or 20 microg Cd litre(-1). Emergence of the Cd-exposed larvae peaked several days before that of the control, although growth was impaired in 1st and/or 2nd instars. The percentage emergence success decreased to about 46% of the control at 40 microg Cd litre(-1). However, other reproductive processes (adult sex ratio, oviposition success and egg hatchability) were not impaired. The emergence success decreased to less than 3% of the control at 80 microg Cd litre(-1). The emergence success of midge larvae which had been fed Cd-contaminated food with 220 or 1800 microg Cd g(-1) decreased to nearly 60% of the control. However, other reproductive processes were not impaired. Emergence success of larvae exposed to food containing 22 microg Cd g(-1) was unaffected.     

Electrocatalytic oxidation of methyl tert-butyl ether (MTBE) in aqueous solution at a nickel electrode

This study utilized the electrocatalytic characteristics of nickel electrode to perform degradation of methyl tert-butyl ether (MTBE) in aqueous solution. Lab experiments were conducted in a spiltless bath type cell equipped with a nickel electrode as working electrode, a platinum wire as counter electrode, and an Ag/AgCl electrode as reference electrode. Effects of controlled potential, supporting electrolyte, and solution pH on the efficiency of MTBE removal were examined under the control of the constant-potential conditions. Experiment results showed that the optimum electrolytic condition was operated at 0.35 V in a 1M KOH electrolyte solution, and the initial 20 mgl(-1) MTBE was reduced by 73% within 180 min under the optimum control. As using 1M Na2SO4 and 1M KCl as electrolyte, the efficiency of MTBE removal dropped to 60% and 50% under the similar controls. Comparing with various pH controls, the strong basic condition is favorable for electrocatalytic oxidation of MTBE in the Ni-electrolytic system. The efficiency of MTBE removal showed a rising trend with increasing initial pH of the solution. The formation of a redox NiOOH/Ni(OH)2 layer on the anode surface, which was observed on the SEM image, can explain that nickel plays a mediator role on improving electrocatalytic oxidation of MTBE at 0.35 V in a strong basic condition. The by-products of MTBE degradation were identified as acetone and CO(2) by GC/MS, and the distributions of carbon atoms in acetone, CO2, and MTBE were found 22%, 51%, and 27% through the optimum control of electrochemical oxidation.     

Removal of pyrene and benzo(a)pyrene from contaminated water by sequential and simultaneous ozonation and biotreatment.

The removal of pyrene and benzo(a)pyrene from contaminated water by sequential and simultaneous ozonation-bioremediation techniques was investigated. During the sequential treatment, ozonation using 0.5 or 2.5 mg/L ozone was used as a pretreatment process, whereas, during the simultaneous treatment process, ozonation of hydrocarbon-contaminated water at a predetermined duration using 0.5 mg/L ozone was made in the presence of microbial biomass. Ozonation was not beneficial for the removal of pyrene. However, despite a decreased specific biodegradation rate, ozonation improved the overall elimination of benzo(a)pyrene during both treatment processes. The overall removal of benzo(a)pyrene increased from 23 to 91% after exposure of the water to 0.5 mg/L ozone for 30 minutes during the simultaneous treatment process and further to 100% following exposure to 2.5 mg/L ozone for 60 minutes during the sequential treatment mode, demonstrating the benefits of combined ozonation-biological treatment for the removal of polycyclic aromatic hydrocarbons.     

Effect of coumaphos on cholinesterase activity, hematology, and biochemical blood parameters of bovines in tropical regions of Mexico

To assess the effect of coumaphos [O-(3-chloro-4-methyl-2-oxo-2H-1-benzopyran-7-yl) O,O-diethyl phosphorothioate] exposure on physiological responses during bovine production, acetylcolinesterase (AChE) and butyrylcholinesterase (BuChE) activities were measured in whole blood, erythrocytes, and plasma of healthy male steers (Bos Taurus x Bos indicus) sprayed with coumaphos at a non-lethal dose of 1 mg kg(- 1) body weight per day once every 14 (in vivo group) or 21 days (southern and central groups). Coumaphos topically administered at 1 mg/kg body weight per day to cattle under normal management practices in tropical areas produced a significant inhibition in erythrocyte (RBC) AChE and BuAChE activities when compared to baseline levels. RBC-AChE activity for the in vivo group decreased 71.3% (P < 0.05) and BuChE activity 59.1% (P < 0.05); RBC-AChE activity decreased 55.1% (P < 0.05) (southern group) and 43.4% (P < 0.05) (central group). Compared to the control specimens, steers from in vivo, southern, and central groups after 150 days of exposure had lower (P < 0.05) leukocyte count, absolute lymphocyte, erythrocyte, and platelet counts. Decreases in RBC-AChE activities correlated with decreased lymphocyte (r = 1.000, p = 0.01), erythrocyte (r = 1.000, p = 0.003), and platelet counts (r = 0.841, p = 0.036). Significantly increased BUN levels (P < 0.05) correlated with the decrease in RBC-AChE activities (r = - 0.997, p = 0.047) and with the decrease in absolute red blood cell (r = - 0.883, p = 0.020) and lymphocyte (r = - 0.825, p = 0.043) counts; increased (P < 0.05) total plasma protein levels correlated with the decrease in RBC-AChE activities (r = -0.998, p = 0.043), absolute red blood cell (r = - 0.998, p = 0.040), lymphocyte (r = - 0.893, p = 0.017), and platelet (r = -0.855, p = 0.030) counts. The physiological responses correlated with the erythrocyte acetylcholinesterase inhibition could be considered as early indicators or warning responses of bovine exposures to organophosphorus pesticides (OPs).     

Toxicity of uranium and copper individually, and in combination, to a tropical freshwater macrophyte (Lemna aequinoctialis)

Copper (Cu) and uranium (U) are of potential ecotoxicological concern to tropical freshwater biota in northern Australia, as a result of mining activities. Few data are available on the toxicity of U, and no data are available on the toxic interaction of Cu and U, to freshwater biota. This study determined the toxicity of Cu and U individually, and in combination, to a tropical freshwater macrophyte, Lemna aequinoctialis (duckweed), in a synthetic soft water (27 degrees C; pH, 6.5; hardness, 40 mg CaCO3 l-1, alkalinity, 16 mg CaCO3 l-1), typical of many fresh surface waters in coastal northern Australia. The growth rate of L. aequinoctialis decreased with increasing Cu or U concentrations, with the concentration of Cu inhibiting growth by 50% (EC50) being 16+/-1.0 microg l-1, with a minimum detectable effect concentration (MDEC) of 3.2 microg l-1. The concentration of U inhibiting growth by 50% (EC50) was 758+/-35 microg l-1 with a MDEC of 112 microg l-1. The EC50 value for the exposure of L. aequinoctialis to equitoxic mixtures of Cu and U was significantly (P0.05) higher than one toxic unit (1.35; 95% confidence interval, 1.18-1.52), indicating that the combined effects of Cu and U are less than additive (antagonistic). Therefore, inhibition of the growth rate of L. aequinoctialis was reduced when Cu and U were present in equitoxic mixtures, relative to individual metal exposures. Since non-additive (e.g. antagonistic) interactions of metal mixtures cannot be predicted using current mixture models, these results have important potential implications for the protection of freshwater ecosystems through the derivation of national water quality guidelines.     

Cell cycle stage specific application of municipal landfill leachates to assess the genotoxicity in root meristem cells of barley (Hordeum vulgare)

Municipal solid wastes (MSW) are unavoidable sources of environmental pollution. Improper disposal of municipal waste results in the leaching of toxic metals and organic chemicals, which can contaminate the surface and ground water leading to serious health hazard. In this study, the toxic effects of the leachate prepared from municipal solid waste samples were examined in root meristem cells of barley (Hordeum vulgare L.) at various stages of cell cycle, i.e., G₁, S, and G₂. Seeds of barley were exposed to 2.5, 5, and 10 % of leachates in soil and aqueous media in 48 h at different cell cycle stages. The physicochemical data of the present study revealed that municipal solid waste leachate contains high amount of heavy metals, which significantly affected growth and physiological activities of barley. Significant inhibition in hypocotyl length, germination, and mitotic index were observed at all concentration of leachate treatment. Induction of chromosomal aberrations (CA’s) and micronuclei (MN) formation were also observed with different concentrations of leachate treatment at 7, 17, and 27 h of presoaking durations, which falls in G₁, S, and G₂ phase of the cell cycle, respectively. Also, exposure of leachate at S phase of the cell cycle had significant effects in barley through chromosomal aberration and micronuclei formation.     

Parts-per-trillion LC-MS(Q) analysis of herbicides and transformation products in surface water

The goal of this study was to develop a robust method of analyzing surface water samples for S-triazine herbicides, chloroacetanilide herbicides, and their transformation products (TPs) using solid-phase extraction (SPE) followed by liquid chromatograph-mass spectrometry (LC-MS) with electrospray ionization (ESI) by in-source collision-induced dissociation (ISCID) capability of an orthogonal electrospray ionization probe on a single quadrupole LC-MS system. The method developed here met the goals of the study and yielded estimated method detection limits (EMDLs) averaging 0.3 ± 0.1 ng L(-1) for S-triazines and their TPs and 0.7 ± 0.4 ng L(-1) for chloroacetanilides and TPs. Spiked filtered river water yielded SPE recoveries ranging from 94.2 % ± 4.8 % for S-triazines and TPs after eliminating three compounds with less that 65 % recovery from analysis and 95.9 % ± 19 % for chloroacetanilides and their TPs. The method was field-tested with filtered water samples collected from four sites over a four-month period. Detectible values of S-triazines and TPs ranged from 0.3 to 1540 ng L(-1) with a mean of 79.3 and a median of 19.4 ng L(-1). Detectible values for chloroacetanilides and TPs ranged from 0.31 to 3780 ng L(-1) with a mean of 252 and a median of 25.6 ng L(-1). An additional goal was to determine if the method was useful for microbial degradation studies using native bacterial communities. The bacteria transformed atrazine (2-chloro-4-ethylamino-6-isopropylamino-S-triazine) solely into 2-hydroxy atrazine (2-hydroxy-4-ethylamino-6-isopropylamino-S-triazine) with concentrations of 78.4, 63.3 and 32.5 ng L(-1) after 12 days of incubation compared with 6.3 and 7.1 ng L(-1) for control dark and control sunlight respectively.     

Use of sensitive methods for detection of DNA damage on human lymphocytes exposed to p,p'-DDT: Comet assay and new criteria for scoring micronucleus test

Wide distribution, stability and long persistence in the environment of dichlorodiphenyltrichloroethane (DDT), probably the best-known and most useful insecticide in the world, imposes the need for further examination of the effect of this chemical on human health and especially on the human genome. In this study, peripheral blood human lymphocytes from a healthy donor were exposed to 0.025 mg/L concentration of p,p'-DDT at different time periods (1, 2, 24 and 48 h). For the assessment of genotoxic effect, the new criteria for scoring micronucleus test and alkaline comet assay were used. Both methods showed that p,p'-DDT induces DNA damage in low concentration used in this research. Results of micronucleus test showed a statistically significant (p < 0.05) genotoxic effect of p,p'-DDT on human lymphocytes compared with corresponding control and a different exposure time. A comet assay also showed increased DNA damage caused in p,p'-DDT-exposed human lymphocytes than in corresponding control cells for the tail length. Results obtained by measuring the level of DNA migration and incidence of micronuclei (MN), nucleoplasmic bridges (NPBs) and nuclear buds (NBUDs) indicate the sensitivity of these tests and their application in detection of primary genome damage after long-term exposure to establish the effect of p,p'-DDT on human genome.     

Distribution of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in human serum from urban areas in Korea

Concentrations of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were determined in serum samples from residents of a Korean urban area (Seoul). This study was performed on 40 Koreans in the general population, aged 27-58, who had resided in urban areas for more than 10 years without occupational exposure to organochlorine pollutants. To our knowledge, this study was the first report on serum concentrations of OCPs in Korean residents. p,p'-DDE, beta-HCH, p,p'-DDT, HCB, and trans-nonachlor were the dominant OCPs in most samples. In addition, concentrations of 22 OCPs were measured by the isotope dilution method with GC-HRMS, which gave accurate and precise data for investigations of trend and international comparisons. The dominant PCBs were PCB153, 138, 180, 187, and PCB118, which contributed 60% to total PCBs. The median concentrations of total OCPs and total PCBs were 315 ng g(-1) lipid and 104 ng g(-1) lipid, respectively. In females, the serum concentrations of all determined organochlorine compounds except beta-HCH were positively correlated with age, and higher concentrations of organochlorine pollutants were found in males than in females. Compared to our previous studies, PCB concentrations in serum from urban areas have substantially decreased during the last decade leading to the observation that the strict regulation of PCBs was helpful in controlling the concentration of PCBs in the environment. Extensive monitoring programs are required for evaluating the concentrations of OCPs and PCBs in serum samples of the general population as an indicator of possible adverse health effects.     

The use of active metabolism and swimming activity to evaluate the toxicity of dodecyl benzene sodium sulfonate (LAS-C12) on the Mugil platanus (Mullet) according to temperature and salinity.

Active metabolism and swimming activity were used to study the effects of dodecyl benzene sodium sulfonate (LAS-C12) in Mugil platanus, a species traditionally considered as estuarine. The effects of exposure to different concentrations of LAS-C12 (0.0, 1.0, 2.5, and 5.0 mg/L) on the active metabolism and swimming activity of Mugil platanus were evaluated. The active metabolism and swimming activity were estimated through experiments conducted on each of 9 possible combinations of three temperatures (35, 20, and 15 degrees C) and three salinities (35, 20, and 5 per thousand). The results show that the active metabolism increases according to the LAS-C12 concentration in all temperatures and salinities studied. At the highest tested concentration (5.0 mg/L), the active metabolism was 111%; 84.8 and 105% higher than the control, at 35 per thousand salinity at the three temperatures. However, the swimming activity decreased according to the LAS-C12 concentration in all temperatures and salinities studied. At the highest tested concentration, the swimming activity was 78.6, 73.6, and 78.7% less than the control, at 25 degrees C at the three salinities. The active metabolism and swimming activity averages, achieved in the different salinities studied, were not significantly different, as a result of the LAS-C12 concentration.