Differential toxicity of silver and titanium dioxide nanoparticles on Drosophila melanogaster development, reproductive effort, and viability: size, coatings and antioxidants matter

Silver and titanium dioxide nanoparticles are known to induce oxidative stress in vitro and in vivo. Here we test if they impact development, mating success, and survivorship in Drosophila melanogaster, and if so, if these effects are reversible by antioxidants. Ingestion of nanotitanium dioxide during the larval stage of the life cycle showed no effects on development or survivorship, up to doses of 200 μg mL⁻¹. Conversely, ingestion of nanosilver had major dose, size, and coating-dependent effects on each of these aspects of life history. Each of these effects was partially or fully reversible by vitamin C. Larvae growing on nanosilver supplemented with vitamin C showed a greater than twofold increase in survivorship compared to flies reared on nanosilver alone, and a threefold increase in mating success. Vitamin C also rescued cuticular and pigmentation defects in nanosilver fed flies. Biochemical assays of superoxide dismutase and glutathione show these markers respond to nanotitanium dioxide and nanosilver induced oxidative stress, and this response is reduced by vitamin C. These results indicate that life history effects of nanosilver ingestion result from oxidative stress, and suggest antioxidants as a potential remediation for nanosilver toxicity. Conversely, the lack of nanotitanium dioxide life history toxicity shows that oxidative stress does not necessarily result in whole organism effects, and argues that nanoparticle toxicity needs to be examined at different levels of biological organization.     

Comparison of heavy metal toxicity in life stages (spermiotoxicity, egg toxicity, embryotoxicity and larval toxicity) of Hydroides elegans

A toxicity test was developed to examine the effects of heavy metal contaminants on the early life stages of the marine polychaete. We have studied the effects of metals on fertilization and early development of marine polychaete Hydroides elegans. These heavy metals have often been found in polluted ground and water near industrial discharges, and have therefore been detected from time to time in the food chain. They have been reported to alter various reproduction functions in various animals including marine populations. The toxic effect of mercury, cadmium, lead, nickel and zinc on sperm viability, fertilization, embryogenesis and larvae of H. elegans was examined. We observed that the rate of fertilization decreased when the sperm was incubated with heavy metals. Treatment of eggs with each metal did not prevent fertilization, but delayed or blocked the first mitotic divisions, and altered early embryonic development. All these effects were observed at relatively high concentrations. However, bio-accumulation in sediments and aquatic organisms have been reported. Polychaete eggs may then be in contact with very high concentrations of these heavy metals in areas where these metals are not handled or stocked properly, and then develop into abnormal embryos. In addition to bivalves and sea-urchins, polychaete embryos can provide biological criteria for seawater quality standards taking into account the sensitivity of the invertebrates and their contribution in detection of harmful chemicals with no marked effect on the species. Our results indicate that the early development of H. elegans is highly sensitive to heavy metals and this polychaete can be routinely employed as a test organism for ecotoxicity bioassays in tropical and subtropical regions.     

饮用水的有机锡问题及对策

有机锡类化合物对环境生态和人类有很强内分泌毒性.其主要来源包括有机锡产品的生产和消耗、生物和化学甲基化效应.当前饮用水日益受到有机锡污染的严重威胁,主要原因有水源水的有机锡污染、PVC管材稳定剂的渗出和管网生物甲基化作用.通过分析提出解决饮用水有机锡问题应从3方面考虑,一是采用紫外光解或化学氧化处理受污染水源水,破坏水中有机锡化合物并消除其毒性;二是加强PVC管材质量要求,尽量采用低毒管材;三是定期更换给水管段以减少管网中生物甲基化导致的二次污染.     

Environmental conditions enhance toxicant effects in larvae of the ground beetle Pterostichus oblongopunctatus (Coleoptera: Carabidae)

The wide geographical distribution of ground beetles Pterostichus oblongopunctatus makes them very likely to be exposed to several environmental stressors at the same time. These could include both climatic stress and exposure to chemicals. Our previous studies demonstrated that the combined effect of nickel (Ni) and chlorpyrifos (CHP) was temperature (T)-dependent in adult P. oblongopunctatus. Frequently the different developmental stages of an organism are differently sensitive to single stressors, and for a number of reasons, such as differences in exposure routes, their interactions may also take different forms. Because of this, we studied the effects of the same factors on the beetle larvae. The results showed that all factors, as well as their interactions, influenced larvae survival. The synergistic effect of Ni and CPF was temperature-dependent and the effect of Ni × T interaction on the proportion of emerged imagines indicated stronger toxicity of Ni at 25 °C than at 10 °C.     

Effect of fluorescent silica nanoparticles in embryo and larva of Oryzias latipes: sonic effect in nanoparticle dispersion

We characterized fluorescent silica nanoparticles (FNPs), which had been applied in many biological systems, in fish embryo rearing media (ERM) solution and evaluated the potential toxicity to the early development of Oryzias latipes embryos. Distribution of FNPs in embryos and larvae of O. latipes was studied by fluorescent and confocal laser scanning microscopic studies. Embryos exposed to three different concentrations of FNPs in stirred or sonicated ERM solutions were observed up to 2 d after hatching. FNPs had a negligible effect on the hatchability of O. latipes embryos; however, compared to controls, more than 30% of eggs were abnormal in 10 and 50 mg FNP L⁻¹ solutions. We found that the toxic effect was increased in sonicated FNP solution, which seems to be related with the dissolution of FNPs in ERM solutions that could be accelerated by sonication. Further study found that the CaCl₂ included in ERM solution might enhance the dissolution of the FNPs and the silicate ion released from FNPs partially contributed to larval toxicity. This study showed that some nanoparticles may not be stable in biological fluids even if they are stable in water. Dissolution factors such as sonication and cellular components should be considered in biological application of nanoparticles.     

Relationship between blood concentrations of heavy metals and cytogenetic and endocrine parameters among subjects involved in cleaning coastal areas affected by the 'Prestige' tanker oil spill

The sinking of the 'Prestige' oil tanker in front of the Galician coast (NW of Spain) in November 2002 offered a unique opportunity to analyze intermediate cytogenetic and endocrine effects among people exposed to the complex mixture of substances that oil constitutes, including several toxic heavy metals. In this work we evaluated the relationship between exposure to heavy metals (blood concentrations of aluminium, cadmium, nickel, lead and zinc) and genotoxic parameters (sister chromatid exchanges, micronucleus test and comet assay) or endocrine parameters (plasmatic concentrations of prolactin and cortisol) in subjects exposed to 'Prestige' oil during cleaning tasks developed after the spillage. Concentrations of lead were significantly related to the comet assay even after adjusting by age, sex and smoking. Cortisol concentrations were significantly influenced by aluminium, nickel (both, inversely) and cadmium (positively). Women had clearly higher concentrations of prolactin and cortisol, even when adjusting by age, smoking, cadmium, aluminium or nickel. Plasmatic cortisol was jointly influenced by gender, smoking and aluminium or nickel (all p<0.05). In women there was a strong relationship between concentrations of cadmium and prolactin (beta=0.37, p=0.031). When the effects of cadmium, aluminium and nickel on cortisol were simultaneously assessed, only the latter two metals remained statistically significant. Among parameters analysed, cortisol appeared to be the most sensitive to the effects of metal exposure. Plasma levels of cortisol deserve further evaluation as a potentially relevant biomarker to assess the effects of exposure to heavy metals.     

Selenium assimilation and loss by an insect predator and its relationship to Se subcellular partitioning in two prey types

Subcellular selenium (Se) distributions in the oligochaete Tubifex tubifex and in the insect Chironomus riparius did not vary with Se exposure duration, which was consistent with the observations that the duration of prey Se exposure had little influence on either Se assimilation or loss by a predatory insect (the alderfly Sialis velata). However, these two prey types differed in how Se was distributed in their cells. Overall, the predator assimilated a mean of 66% of the Se present in its prey, which was similar to the mean percentage of Se in prey cells (62%) that was theoretically available for uptake (that is, Se in the protein and organelle fractions). Likewise, data for cadmium, nickel and thallium suggest that predictions of trace element transfer between prey and predator are facilitated by considering the subcellular partitioning of these contaminants in prey cells.     

Acute and chronic toxicities of tributyltin to various life stages of the marine polychaete Hydroides elegans

Experiments were performed to determine the acute and chronic toxicities of tributyltin (TBT) (nominal concentrations) to polychaete Hydroides elegans. Firstly, static tests were performed to examine the lethal effect of TBT on five life stages of H. elegans. The 48-h LC(50) (95% CI) for the eggs, 2-cells, trochophores, juveniles and adults was 0.18 (0.15-0.20), 0.97 (0.77-1.23), 2.36 (2.11-2.65), 2.86 (2.63-3.12) and 4.36 (4.04-4.71) microg TBT l(-1), respectively. Secondly, a 17-d static renewal chronic test was conducted to study sensitivity of the early development (egg to juvenile) to TBT. The survivorship, percent settlement and time to reach settlement were significantly reduced at 0.01 microg TBT l(-1). Effects of TBT on the juvenile growth and maturation were also studied through a 44-d chronic test. Lower survivorship and reduced tube growth were observed only at >or= 1 microg TBT l(-1), however, only H. elegans exposed to or= 0.1 microg TBT l(-1). Our results indicate that the early development of H. elegans is highly sensitive to TBT and this polychaete can be routinely employed as a test organism for both acute and chronic ecotoxicity bioassays in tropical and subtropical regions such as southern China.     

Graduate Education for Air Pollution Control Personnel

Tendergreen bean plants were grown from seeding to seed maturity under continuous exposure to HF gas at fairly uniform concentrations averaging 0.58, 2.1, 9.1, and 10.5 µg F/m³. Progeny of these plants and of comparable control plants were grown in a clean atmosphere to determine if subsequent generations were affected by HF treatment of the parents.

No effects of HF were found among the progeny of the plants grown at 0.58 µg F/m³. The F₁ generation progeny of the other HF treated plants were less vigorous than control plant progeny, as shown by later emergence, smaller primary leaves, and slower stem growth. This probably was a consequence of the lower starch content of the seed of the HF treated plants. The primary leaves of some F₁ progeny of the plants grown in the three highest HF treatments were severely stunted and distorted. This also may have been due to the low starch content of the seed, or perhaps it resulted from damage to the plumules in shriveled, distorted seed produced in these treatments.

Some of the early trifoliate leaves of many F₁ generation progeny of the plants grown at 2.1 µg F/m³ and higher were abnormal in the separation and number of their leaflets. This abnormality apparently was heritable, for in the next (F₂) generation it occurred most frequently among plants whose parents were abnormal. However, considerably fewer F₃ generation plants had abnormal trifoliate leaves, indicating rapid reversal to the normal form.     

Developmental dental defects in children exposed to PCBs in eastern Slovakia

The effects of long-term exposure to polychlorinated biphenyls (PCBs) on developmental dental defects of deciduous and permanent teeth in children in eastern Slovakia, where PCBs from a chemical plant manufacturing Delors contaminated the surrounding district were evaluated. Four hundred and thirtytwo children, lifelong residents, aged 8-9 years were examined. Children's caries susceptibility and gingival health was assessed by standard dental indices, and developmental enamel defects by the FDI index. Data from the PCBRISK project data set and questionnaires completed by the parents provided information on exposure and various confounding factors. The proportion of teeth with different types and extensions of developmental enamel defects correlated with serum PCB concentration. The proportion of deciduous teeth affected with enamel defects was significantly higher in higher exposed children (chi(2)=8.35; p=0.03) according to their serum PCB concentration (group 0: <200; group 1: 200-600; group 2: >600 ng PCBs g(-1) serum lipids). The proportion of permanent teeth affected with any enamel defect was significantly higher in higher exposed children (chi2=7.237; p=0.027). Furthermore, the extent of the enamel defects was also greater (chi2=10.714; p=0.005). In multivariate linear regression analysis PCB exposure was significantly related to developmental enamel defects of permanent teeth only. No associations between PCB exposure and caries susceptibility, gingival health or number of teeth were observed. This study demonstrated a dose-response relationship between PCB exposure and developmental enamel defects of permanent teeth in children, the evidence for deciduous teeth was not conclusive.     

Toxic and developmental effects of organophosphorus insecticides in embryos of the South African clawed frog

Four organophosphorus insecticides and the active metabolites of two phosphorothionate insecticides were tested for their toxic and teratogenic effects on embryos of Xenopus laevis. All compounds caused dose-dependent developmental defects, such as abnormal pigmentation, abnormal gut development, notochordal defects and reduced growth. Malathion, malaoxon, parathion, and paraoxon produced severe defects, while monocrotophos and dicrotophos produced considerably milder defects. All compounds reduced NAD+ levels to a similar extent, regardless of the severity of the defects induced. Thus some commonly used organophosphorus insecticides and their metabolites are teratogenic to Xenopus embryos, but reduced NAD+ level does not appear to be important in causing the developmental defects.     

Multigenerational cadmium acclimation and biokinetics in Daphnia magna

A Cd exposure (3 microg L(-1)) experiment was conducted for six successive generations to investigate the responses to chronic Cd stress in Daphnia magna. We observed a biphasic accumulation of Cd in the six generations and suggested a similar pattern with respect to daphnids' tolerance. Cd assimilation efficiencies, daphnid growth, and reproduction corresponded to the changes of tolerance, which was partially accounted for by metallothionein induction. When maternally exposed neonates grew in Cd-free water for one or two generations, their growth, MT concentration and biokinetic parameters partially or totally recovered. The rapid recovery suggests the high potential for ecological restoration from Cd pollution. Our results indicate that the tolerance of sensitive D. magna clones to Cd was dependent on long-term or multigenerational exposure. The tolerance developed within the first several generations might not be maintained, and the animals may become even more sensitive to Cd stress in subsequent generations.     

Development of a novel mathematical model using a group contribution method for prediction of ionic liquid toxicities

A new mathematical model has been developed that expresses the toxicities (EC₅₀ values) of a wide variety of ionic liquids (ILs) towards the freshwater flea Daphnia magna by means of a quantitative structure-activity relationship (QSAR). The data were analyzed using summed contributions from the cations, their alkyl substituents and anions. The model employed multiple linear regression analysis with polynomial model using the MATLAB software. The model predicted IL toxicities with R² = 0.974 and standard error of estimate of 0.028. This model affords a practical, cost-effective and convenient alternative to experimental ecotoxicological assessment of many ILs.     

Use of blood parameters in fish to assess acidic stress and chloride pollution in French running waters

The study investigated whether plasmatic parameters in fish such as Cl- content could serve as physiological indicators to evaluate water quality. The variations of plasma Cl- content in two fish species caught in a wide range of rivers representative of the hydrographic system of Lorraine (N-E France) were investigated. First, we studied autochthonous populations of chub (Leuciscus cephalus) which is a widespread species in the rivers of Lorraine. Organisms living in highly mineralised rivers (>1500 microScm(-1))--either naturally or due to salt mine contamination--showed plasma Cl- content significantly greater than organisms living in river with a lower mineralisation. Second, we investigated plasma Cl- content of brown trout (Salmo trutta fario) in poorly mineralised streams (<80 microS cm(-1)) with different degrees of acidification, both on autochthonous and transferred organisms. While indigenous trout maintained their Cl- content even in the acidic streams, transferred trout exhibited an important decrease of Cl- content after 48 h of exposure under acidic conditions.     

Assessing benzene-induced toxicity on wild type Euglena gracilis Z and its mutant strain SMZ

Benzene is a representative member of volatile organic compounds and has been widely used as an industrial solvent. Groundwater contamination of benzene may pose risks to human health and ecosystems. Detection of benzene in the groundwater using chemical analysis is expensive and time consuming. In addition, biological responses to environmental exposures are uninformative using such analysis. Therefore, the aim of this study was to employ a microorganism, Euglena gracilis (E. gracilis) as a putative model to monitor the contamination of benzene in groundwater. To this end, we examined the wild type of E. gracilis Z and its mutant form, SMZ in their growth rate, morphology, chlorophyll content, formation of reactive oxygen species (ROS) and DNA damage in response to benzene exposure. The results showed that benzene inhibited cell growth in a dose response manner up to 48 h of exposure. SMZ showed a greater sensitivity compared to Z in response to benzene exposure. The difference was more evident at lower concentrations of benzene (0.005–5 μM) where growth inhibition occurred in SMZ but not in Z cells. We found that benzene induced morphological changes, formation of lipofuscin, and decreased chlorophyll content in Z strain in a dose response manner. No significant differences were found between the two strains in ROS formation and DNA damage by benzene at concentrations affecting cell growth. Based on these results, we conclude that E. gracilis cells were sensitive to benzene-induced toxicities for certain endpoints such as cell growth rate, morphological change, depletion of chlorophyll. Therefore, it is a potentially suitable model for monitoring the contamination of benzene and its effects in the groundwater.     

Accumulation of heavy metals and antioxidant responses in Vicia faba plants grown on monometallic contaminated soil

The purpose of this study was to explore the effects of soil contamination by selected metals (cadmium, copper, nickel, lead or zinc) on the antioxidant response of Vicia faba plants. The levels of the antioxidants: glutathione, proline, non-protein thiols, as well as guaiacol peroxidase and catalase activities were measured in the upperparts of plants. Additionally, the potential bioavailability of metals in the soil and their concentrations in V. faba plants were compared. Treatment with metal caused the problem of an elevation in its bioavailability in soil and its concentration in leaves and stems. The most serious problems seemed to be metal elevations in soil, especially Zn and Ni as well as in the aerial parts of V. faba plants. The antioxidant responses appeared to be metal specific. The elevation of guaiacol peroxidase activity in leaves and stems as well as the proline in leaves was the only more general reaction to metal exposure. Upon analysis of the effects of soil metal contamination on V. faba plants, we recommend the use of some measurements such as guaiacol peroxidase activity and proline level as useful tools in biological monitoring.     

Histopathological changes in the earthworm Eisenia andrei associated with the exposure to metals and radionuclides

Earthworms were exposed for 56 d to a contaminated soil, from an abandoned uranium mine, and to the natural reference soil LUFA 2.2. Histological changes in earthworm’s body wall (epidermis, circular and longitudinal muscles) and gastrointestinal tract (chloragogenous tissue and intestinal epithelium) were assessed, after 0, 14 and 56 d of exposure. Results have shown alterations in all the studied tissues after 14 d of exposure (except for the intestinal epithelium), yet more severe effects were registered after 56 d of exposure. Herein we report histopathological alterations as a good biomarker for the evaluation of soil quality. We also demonstrate that morphological changes in the body wall and gastrointestinal tract, are important endpoints that could be added to earthworm’s standardized tests, for the evaluation of soil toxicity, as part of the risk assessment of contaminated areas.     

Chemical sensitivity of the male daphnid, Daphnia magna, induced by exposure to juvenile hormone and its analogs

It was reported that males daphnid Daphnia magna that have been induced by methyl farnesoate exposure exhibit higher tolerance to chemical compounds such as potassium dichromate and pentachlorophenol than females. Male neonates are also known to be induced by exposure to juvenile hormone analogs, such as fenoxycarb and pyriproxyfen. If these analogs can be used to produce male progeny, the biological and physiological studies of daphnid male would be progressed since the effects of these analogs were several hundred times higher than that of methyl farnesoate. Therefore, in the present study, it was investigated that the chemical sensitivity of male neonates induced by exposure to juvenile hormone (methyl farnesoate) and its analogs. The minimum concentrations of methyl farnesoate, fenoxycarb and pyriproxyfen to induce 100% male-reproduction were 200nM (50microg/l), 0.23nM (70ng/l) and 0.31nM (100ng/l), respectively. In addition, no reduction of relative reproduction was observed at the juvenoid concentrations in 24h exposure producing 100% male progeny. The median effective concentrations (EC50) of potassium dichromate for immobility of male neonates, established by a standardized method for investigating sensitivity to chemicals, were significantly higher (12-29%) than that of females at least after 24h exposure in all the male neonates induced by juvenoids used in this study (P<0.05). This study demonstrated that the male daphnids induced by exposure to juvenile hormone and its analogs exhibit similar chemical tolerance.     

Towards a renewed research agenda in ecotoxicology

New concerns about biodiversity, ecosystem services and human health triggered several new regulations increasing the need for sound ecotoxicological risk assessment. The PEER network aims to share its view on the research issues that this challenges. PEER scientists call for an improved biologically relevant exposure assessment. They promote comprehensive effect assessment at several biological levels. Biological traits should be used for Environmental risk assessment (ERA) as promising tools to better understand relationships between structure and functioning of ecosystems. The use of modern high throughput methods could also enhance the amount of data for a better risk assessment. Improved models coping with multiple stressors or biological levels are necessary to answer for a more scientifically based risk assessment. Those methods must be embedded within life cycle analysis or economical models for efficient regulations. Joint research programmes involving humanities with ecological sciences should be developed for a sound risk management.     

Assessment of the effects of nickel on benthic macroinvertebrates in the field

A field-based evaluation of the biological effects of potential nickel (Ni) exposures was conducted using monitoring data for benthic macroinvertebrates and water chemistry parameters for streams in England and Wales. Observed benthic community metrics were compared to expected community metrics under reference conditions using RIVPACS III+?software. In order to evaluate relationships between Ni concentrations and benthic community metrics, bioavailable Ni concentrations were also calculated for each site. A limiting effect from Ni on the 90th percentile of the maximum achievable ecological quality was derived at “bioavailable Ni” exposures of 10.3 μg l^?1. As snails have been identified as particularly sensitive to nickel exposure, snail abundance in the field in response to nickel exposure, relative to reference conditions, was also analysed. A “low effects” threshold for snail abundance based on an average of spring and autumn data was derived as 3.9 μg l^?1 bioavailable Ni. There was no apparent effect of Ni exposure on the abundance of Ephemeroptera (mayflies), Plecoptera (stoneflies) or Tricoptera (caddisflies) when expressed relative to a reference condition within the range of “bioavailable Ni” exposures observed within the dataset. Nickel exposure concentrations co-vary with the concentrations of other stressors in the dataset, and high concentrations of Ni are also associated with elevated concentrations of other contaminants.