Joint Toxicity of Copper and Zinc to a Terrestrial Nematode Community in an Acid Sandy Soil

Heavy metal toxicity to an indigenous nematode community was examined following the addition of Cu and Zn, alone or in combination, to agricultural soil. The dissolved Cu or Zn concentrations measured after equilibrating soil samples with a 0.01 M solution of CaCl₂ showed that the metal concentrations found in soils with combined metal additions were not significantly different from those with single metal additions. After an exposure period of six months, many nematode community parameters and individual nematode taxa were significantly affected by increasing concentrations of Cu and Zn up to 200 mg kg^–1. Some nematode taxa, such as Thonus, Alaimus and Aporcelaimellus were very sensitive and disappeared at Cu and Zn concentrations exceeding 50 mg kg^–1. For several nematode community parameters and nematode taxa, EC₅₀ values for single metal exposures were used to calculate TU₅₀ values for the joint toxicity of Cu and Zn. Based on these calculations, it is concluded that the effects of a combined exposure to Cu and Zn were additive or less than additive. Before this conclusion can be generalised, however, more data are needed on other types of soil, other pH values and other combinations of pollutants.     

Effects of Diet and Soil on the Toxicity of Lead in Mallards

Captive game-farm mallards (Anas platyrhynchos) were dosed with five No. 4 lead (Pb) shot and placed on a diet of shelled corn or commercial duck food (6 ducks). Half of the ducks on each diet was dosed daily with 10 g of soil. The commercial duck food provided more protection from the effects of Pb toxicity than the 10 g of soil dosed daily. Ducks on corn only died a mean of 7 days after dosing, ducks receiving commercial duck food, with and without soil, survived to the end of the study (21 days after dosing), and ducks receiving a diet of corn and soil survived an average of 17 days. Although ducks receiving corn only dissolved less Pb, excreted less Pb in their feces, and retained less dissolved Pb than the ducks receiving the other three treatments, they retained more dissolved Pb per day than the other ducks.     

Effects of Diet and Soil on the Toxicity of Lead in Mallards

Captive game-farm mallards (Anas platyrhynchos) were dosed with five No. 4 lead (Pb) shot and placed on a diet of shelled corn or commercial duck food (6 ducks). Half of the ducks on each diet was dosed daily with 10 g of soil. The commercial duck food provided more protection from the effects of Pb toxicity than the 10 g of soil dosed daily. Ducks on corn only died a mean of 7 days after dosing, ducks receiving commercial duck food, with and without soil, survived to the end of the study (21 days after dosing), and ducks receiving a diet of corn and soil survived an average of 17 days. Although ducks receiving corn only dissolved less Pb, excreted less Pb in their feces, and retained less dissolved Pb than the ducks receiving the other three treatments, they retained more dissolved Pb per day than the other ducks.     

Toxicity of Organic Compounds to Marine Invertebrate Embryos and Larvae: A Comparison Between the Sea Urchin Embryogenesis Bioassay and Alternative Test Species

This study investigated the toxic effects of the insecticides lindane and chlorpyrifos, the herbicide diuron, the organometallic antifoulant tributyltin (TBT), and the surfactant sodium dodecyl sulfate (SDS) on the early life stages of Paracentrotus lividus (Echinodermata, Euechinoidea), Ciona intestinalis (Chordata, Ascidiacea), Maja squinado and Palaemon serratus (Arthropoda, Crustacea) in laboratory acute toxicity tests. The assays studied embryogenesis success from fertilized egg to normal larvae in P. lividus (48 h incubation at 20 °C) and C. intestinalis (24 h incubation at 20 °C), and larval mortality at 24 and 48 h in M. squinado and P. serratus. For P. lividus, the median effective concentrations (EC₅₀) reducing percentages of normal larvae by 50% were: 350 g l^–1 for chlorpyrifos, 5500 g l^–1 for diuron, 4277 g l^–1 for SDS, and 0.309 g l^–1 for TBT. For C. intestinalis, the EC₅₀ values affecting embryogenesis success were 5666 g l^–1 for chlorpyrifos, 24,397 g l^–1 for diuron, 4412 g l^–1 for lindane, 5145 g l^–1 for SDS, and 7.1 g l^–1 for TBT. The median lethal concentrations (LC₅₀) for M. squinado larval survival were 0.84 g l^–1 (24 h) and 0.79 g l^–1 (48 h) for chlorpyrifos, 2.23 g l^–1 (24 h) and 2.18 g l^–1 (48 h) for lindane, and 687 g l^–1 (48 h) for SDS. For P. serratus the LC₅₀ values obtained were 0.35 g l^–1 (24 h) and 0.22 g l^–1 (48 h) for chlorpyrifos, 3011 g l^–1 (24 h) and 3044 g l^–1 (48 h) for diuron, 5.20 g l^–1 (24 h) and 5.59 g l^–1 (48 h) for lindane, and 22.30 g l^–1 (24 h) and 17.52 g l^–1 (48 h) for TBT. Decapod larvae, as expected, were markedly more sensitive to the insecticides than sea urchins and ascidians, and SDS was the least toxic compound tested for these organisms. Lowest observed effect concentrations (LOEC) of TBT for sea urchin and ascidian embryos, chlorpyrifos and lindane for crustacean larvae, and SDS, were similar to those found in many coastal areas indicating that there would be a risk to invertebrate embryos and larvae from exposure in the field to these pollutants.     

Impacts on reproduction of Enchytraeus crypticus in fertilized soils with chicken litter treated with synthetic and natural insecticide

Poultry litter is used as a fertilizer due to the high concentration of nutrients. However, this material receives application of medicines, whether they are used to treat animals or the litter itself. Thus, the objective was to evaluate if the application in soils of poultry litter doses treated with two insecticides (cypermethrin and cinnamon oil) used to control of the Alphitobius diaperinus, affect the reproduction of Enchytraeus crypticus, and the insecticides effects over time, trough of ecotoxicological tests using soils with different textural classes an Entisol and an Oxisol. In the Oxisol the application of poultry litter stimulated the E. crypticus reproduction regardless of the insecticide and the collection time. In Entisol the poultry litter showed a toxicity at 10 t ha⁻¹ when treated with cypermethrin and at 30 t ha⁻¹ with cinnamon oil. Entisol results show that cypermethrin affects non-target edaphic organisms soon after spraying, but over time has reduced toxicity unlike cinnamon oil.     

Application of the Tukey Trend Test Procedure to Assess Developmental and Reproductive Toxicity: I. Measurement Data

Developmental and reproductive (DAR) toxicity studies typicallyinclude a series of increasing doses of a compound and a zerodose control. Given this framework, Tukey et al. (Biometrics,41, 295–;301, 1985) proposed a procedure (referred toas either the Tukey trend or TCH test procedure) for detectinga nonzero trend in response to increasing doses of the testcompound. The procedure considers three candidate dosage scalingsto ensure high power against relatively common dose-responsepatterns and appreciable power against most reasonable patterns.For toxicologic effects with near monotonic dose-response patterns,simulation studies have shown the TCH test to be overall morepowerful than pairwise comparison procedures. The TCH test canbe applied sequentially, eliminating the highest dose each timea statistically significant trend is observed, until a no-statistical-significance-of-trenddose is reached. This is the highest dose through which thereis no statistically trustworthy evidence of the compound's impacton the response. Since DAR toxicity usually exhibits a progressive(monotonic) dose-response, we advocate routine use of Tukey'strend test for the evaluation of treatment effects in thesestudies. In this article, we discuss the procedure in detailand apply it to fetal body weight, a continuous measurementvariable, from a developmental toxicity study.     

Influence of Garlic on the Disposition and Toxicity of Lead and Cadmium in the Rat

Garlic (Allium sativum L., Liliaceae) was investigated for its potential to prevent the accumulation of lead or cadmium, major environmental pollutants, and to reduce their toxic effects in rats. The oral feeding of minced fresh garlic during intraperitoneal injection of lead acetate or cadmium chloride, daily for 6 weeks significantly decreased the accumulation of these toxic metals and prevented the metal sensitive biochemical alterations in blood, liver and kidney. The ability of garlic to provide glutathione, biosynthesize metallothionein or similar protein, and its antioxidant properties appear to protect against potential oxidative damage to tissues by lead or cadmium. The regular intake of garlic may be beneficial in reducing the toxic effects of these heavy metals in the exposed population.     

Toxicity of phenanthrene and lindane mixtures to marine invertebrates

Surface waters near industrialized and agricultural areas are contaminated with hundreds of different pollutants from a variety of sources. Methods for measurement of sediment, surface water, and porewater toxicity in marine environments include the sea urchin (Arbacia punctulata) fertilization and embryological development tests and copepod (Schizopera knabeni) survival and hatching success assessment. The concentration addition model was applied to determine whether toxicity of two compounds, phenanthrene (polycyclic aromatic hydrocarbon) and lindane (organochlorine pesticide), when combined can be accurately assessed because of similar modes of action. Mixture analysis determined the sea urchin fertilization test to exhibit additivity (TU(mix) = 1.13), while the copepod test exhibited a synergistic effect (TU(mix) = 0.22). Mixture toxicity data for the sea urchin embryological test were not conclusive because of the lack of toxicity of the individual chemicals. The synergistic effect to copepods is a concern as it indicates that greater toxic effects may occur when the compounds are present in mixtures. Results from this research suggest that increased toxicity to some categories of organisms should be expected near agricultural and industrial areas where pesticides and other types of compounds may occur simultaneously.     

Antioxidant and neurotoxicity markers in the model organism Enchytraeus albidus (Oligochaeta): mechanisms of response to atrazine,dimethoate and carbendazim

The present study aimed to investigate the effects of dimethoate, atrazine and carbendazim on the antioxidant defences and neuronal function of the soil organism Enchytraeus albidus. Effects were studied at concentrations known to affect their reproduction (EC₂₀, EC₅₀ and EC₉₀) and along time (2, 4, 8, 14 and 21 days). In general, responses were more pronounced at periods of exposure longer than 8 days and at the highest concentrations. Multivariate statistics (RDA-PRC) clearly displayed that exposure duration had an effect itself, biomarkers’ responses showed interaction for all pesticides and catalase scored consistently high, indicating its relevancy in the group of measured markers. Univariate analysis indicated oxidative stress for all pesticides and atrazine induced oxidative damage in lipids. Atrazine seems to be effectively metabolized by GST of the biotransformation system, as its activity significantly increased after exposure to this pesticide. Dimethoate caused ChE inhibition, indicating an impairment of the neuronal function. Carbendazim impaired the antioxidant system, but no oxidative damage was observed, along with any effects on the ChE activity. The integrated biomarker response analysis was performed but we suggest modifications due to limiting artefacts.     

Influence of copper treatment on bioaccumulation,survival, behavior,and fecundity in the fruit fly Drosophila melanogaster: Toxicity of copper oxide nanoparticles differ from dissolved copper

Copper oxide (CuO) NPs are widely used and subsequently released into terrestrial ecosystems. In the present study, bioaccumulation and effects of CuO NPs and dissolved Cu was examined in the fruit fly Drosophila melanogaster after 7 and 10 days dietary exposure at concentrations ranging between 0.09 and 1.2 mg Cu ml⁻¹ for dissolved Cu and between 0.2 and 11 mg Cu ml⁻¹ for CuO NPs. Both Cu forms were bioaccumulated and affected survival and climbing in flies, but not egg-to-adult development. Dissolved Cu caused higher mortality than CuO NPs (CuO NPs 10-days LC₅₀ was 2 times higher), whereas NPs affected climbing and decreased the number of eggs laid per female, potentially affecting fruit fly population size in terrestrial environments. Thus, the study indicates that CuO NPs might cause effects that are different from dissolved Cu due to differences in the mechanism of uptake or toxicity. Therefore, we need to consider relevant sublethal endpoints when assessing these CuO NPs to ensure that we do not overlook long-term effects.     

The Use of Integrated Soil Microcosms to Assess the Impact of Carbendazim on Soil Ecosystems

Our investigation used carbendazim as a representative pesticide for testing an integrated soil microcosm (ISM) test protocol. Microcosms, set up in a greenhouse, consisted of cylinders made from high-density polyethylene (HDPE) pipe, 7.5 cm (i.d.) × 15 cm high. A fine nylon mesh was placed across the bottom of each microcosm for leachate collection. Field soil, (silty clay loam), collected from Flörsheim, Germany, was sieved through a 5 mm screen and mixed thoroughly. Earthworms, enchytraeids, and microarthropods were added to each microcosm. Each microcosm contained five wheat seedlings, and was maintained at a 12 h–12 h light–dark cycle. Artificial rainwater was used to water microcosms as required. Soil microcosms were treated with carbendazim at concentrations 1, 3, 9, 27, and 81 times higher than the predicted environmental concentration (PEC) of 0.76 mg a.i./kg soil dry weight. A water-only control treatment was also used. The key soil processes used as endpoints were microbial activity, nitrogen mineralization, soil enzymatic activity, ammonium and nitrate leaching, organic matter decomposition and biological feeding activity. Key structural parameters measured were microbial biomass, nematode communities, microarthropod populations and diversity, enchytraeid and earthworm populations and plant growth. Pesticide degradation, leaching and uptake into plants and earthworms were also assessed. Carbendazim had significant effects on several key soil processes including soil ammonium-N and nitrate-N concentrations and soil dehydrogenase activity. Wheat growth, nematode and earthworm populations, and invertebrate feeding activity were soil structural parameters affected significantly by carbendazim. Earthworm biomass was the most sensitive parameter measured with an EC₅₀ of 1.9 mg a.i./kg soil dry weight 28 days after treatment. A comparison of these results with results from single-species tests, small microcosms, large terrestrial model ecosystems, and field tests indicated that the ISM protocol may adequately predict environmental effects.     

Aquatic Insects and Trace Metals: Bioavailability,Bioaccumulation, and Toxicity

Abstract

The uptake of metals from food and water sources by insects is thought to be additive. For a given metal, the proportions taken up from water and food will depend both on the bioavailable concentration of the metal associated with each source and the mechanism and rate by which the metal enters the insect. Attempts to correlate insect trace metal concentrations with the trophic level of insects should be made with a knowledge of the feeding relationships of the individual taxa concerned. Pathways for the uptake of essential metals, such as copper and zinc, exist at the cellular level, and other nonessential metals, such as cadmium, also appear to enter via these routes. Within cells, trace metals can be bound to proteins or stored in granules. The internal distribution of metals among body tissues is very heterogeneous, and distribution patterns tend to be both metal and taxon specific. Trace metals associated with insects can be both bound on the surface of their chitinous exoskeleton and incorporated into body tissues. The quantities of trace meals accumulated by an individual reflect the net balance between the rate of metal influx from both dissolved and particulate sources and the rate of metal efflux from the organism. The toxicity of metals has been demonstrated at all levels of biological organization: cell, tissue, individual, population, and community. Much of the literature pertaining to the toxic effects of metals on aquatic insects is based on laboratory observations and, as such, it is difficult to extrapolate the data to insects in nature. The few experimental studies in nature suggest that trace metal contaminants can affect both the distribution and the abundance of aquatic insects. Insects have a largely unexploited potential as biomonitors of metal contamination in nature. A better understanding of the physico-chemical and biological mechanisms mediating trace metal bioavailability and exchange will facilitate the development of general predictive models relating trace metal concentrations in insects to those in their environment. Such models will facilitate the use of insects as contaminant biomonitors.     

Effect of Varying Physicochemistry of European Surface Waters on the Copper Toxicity to the Green Alga <Emphasis Type="Italic">Pseudokirchneriella subcapitata</Emphasis>

Most standard toxicity test results, used in present environmental risk assessment and water quality criteria (WQC) setting procedures are obtained with standard test media that are not representative for natural surface waters when metal toxicity modifying factors like pH, water hardness and dissolved organic carbon (DOC) are considered. The aim of this study was, using the green alga Pseudokirchneriella subcapitata, (1) to investigate the individual effects of Ca, Mg (the hardness cations) and pH on the toxicity of copper in reconstituted artificial test waters and (2) to study the copper toxicity in 13 spiked surface waters originating from different European eco-regions. Surface waters were selected such that a broad range of DOC (1.55–20.4 mg/l), pH (5.52–8.30) and water hardness (7–238 mg CaCO₃/l) was covered. Tests in reconstituted artificial waters demonstrated that the 72 h-E_bC50 (expressed as dissolved Cu) increased by about a factor of 3 when the Ca and Mg concentrations increased from 0.25 to 2.5 mM. When pH was increased from 5.8 to 8.0, dissolved 72 h-E_bC50 decreased by a factor of 3. It is suggested that competition between Cu²⁺, Ca²⁺, Mg²⁺ and H⁺ ions at the cell surface are the most likely explanation for these observations. Dissolved 72 h-E_bC50s in the natural surface waters varied between 32.0 and 245 μg Cu/l and were up to a factor 15 higher than the 72 h-E_bC50 in standard artificial medium (16.5±4.8 μg Cu/l). Consequently, Water Effect Ratio’s (WER, the ratio between the EC50 in natural water to the EC50 in standard test water) ranged from 1.9 to 14.8. Linear regression analysis revealed that higher E_bC50 were significantly related to higher DOC-concentration of the natural waters (R ² = 0.69), but that water hardness and pH did not show a significant relation with copper toxicity in these surface waters. In European surface waters, a positive correlation is observed between water hardness and pH. As a result, hardness and pH effects on copper toxicity are counteractive in European surface waters, resulting in the highly significant relation between the 72 h-E_bC50 and DOC-concentration. Normalisation of the obtained effect concentrations using a Biotic Ligand based predictive Cu-toxicity model revealed that variation in DOC and pH are mainly responsible for the observed differences of Cu-toxicity in natural waters.     

Comparison of the Effect of Different pH Buffering Techniques on the Toxicity of Copper and Zinc to <Emphasis Type="Italic">Daphnia Magna</Emphasis> and <Emphasis Type="Italic">Pseudokirchneriella Subcapitata</Emphasis>

During the time-course of ecotoxicity tests with algae and chronic (reproductive) toxicity tests with daphnids, in which algae are present as a food source, pH can dramatically increase due to photosynthetic activity. As pH changes can significantly affect metal speciation and thus its bioavailability, it may be necessary to buffer the pH of the exposure medium. One class of buffers (Goods N-subtituted aminosulfonic acids) are increasingly being used in biological and chemical applications, including ecotoxicity testing. However, the potential effect of these buffers on metal toxicity has, so far, scarcely been examined. In this study we investigated if MOPS (3-N morpholino propane sulfonic acid) affected the toxicity of copper and zinc to two standard test organisms: the cladoceran Daphnia magna and the green alga Pseudokirchneriella subcapitata. First, we demonstrate that up to a concentration of 750 mg l^–1 (which proved to be sufficient for pH buffering) MOPS did not affect 21-day net reproduction of D. magna or the 72-h population growth of P. subcapitata. Second, we conducted bioassays in copper and zinc spiked standard media for the pH range 6 – 8. For D. magna the possible effect of 750 mg l^–1 MOPS on acute copper and zinc toxicity was investigated by performing parallel 48-h toxicity tests in NaHCO₃ and MOPS buffered test media. Seventy-two hour growth inhibition assays with P. subcapitata were performed in parallel in MOPS and NaHCO₃ buffered test media and in test media with daily manual pH adjustment with HCl. For daphnids no significant differences in copper and zinc toxicity were observed between MOPS or NaHCO₃ buffered test media. For algae no significant differences in metal toxicity were observed between MOPS and HCl buffered media, but in test media buffered with NaHCO₃ an increased copper and zinc toxicity was observed as a consequence of pH increases during the test. Clearly, the results of this study demonstrate the importance of pH buffering in metal toxicity testing and the suitability of the MOPS buffer for that purpose.     

Exposure of a Tropical Soil to MG/KG of Oxytetracycline Elicits Hormetic Responses in the Catabolic Activities of Its Microbial Community

Many farmers in developing countries protect their crops with oxytetracycline and fertilize their farmlands with manure from animals that received this drug as growth promoter. In this study, a tropical soil was exposed to 0.1 mg kg(-1), 1 mg kg(-1), and 10 mg kg(-1) of oxytetracycline for 22 days to evaluate whether this antibiotic alters the capacity of a soil microbial community to metabolize 31 carbon sources. The communities exposed to 1 and 10 mg kg(-1) of oxytetracycline exhibited reduced catabolic activities for 3 and 6 substrates, respectively. In contrast, the communities exposed to 0.1 mg kg(-1) of oxytetracycline showed higher catabolic activities than the controls and the other two treatments for 19 substrates. These data reveal a hormetic response at the community level not previously described for soil bacteria and oxytetracycline.     

Influence of food on the absorption of phenytoin in man

Summary The influence of food intake on the absorption of phenytoin was examined in eight healthy volunteers, by study of single-dose kinetics following ingestion of phenytoin 300 mg either with a standardized breakfast or on an empty stomach. Blood samples were collected at regular intervals from 0 to 48 h, and serum concentrations of unmetabolized phenytoin were determined by gas chromatography. Serum concentrations of the major metabolite of phenytoin, 4-hydroxyphenytoin, were measured by mass fragmentography. Concurrent intake of food and phenytoin appeared to accelerate absorption of the drug from the formulation used, and the peak concentrations were significantly higher (mean increase 40%) in the postprandial than in the preprandial state. As reflected by the AUC (area under the curve), the amount of drug absorbed was increased during postprandial conditions, although the difference only reached borderline significance. It is suggested that phenytoin should always be taken in a defined relation to meals.     

壳聚糖对重金属离子Cu和Pb的吸附研究

目的处理实验室废水中的重金属离子。方法本文对壳聚糖对模拟废水中的微量重金属离子Cu和Pb的吸附进行了研究,确定了最佳吸附条件。结果在实验室条件下,Cu2＋的最佳pH=9,Pb2＋的最佳pH=6,壳聚糖最佳用量均为10g/L,最佳吸附时间均为20min,温度均为常温,壳聚糖脱乙酰度均为85%。结论壳聚糖对水中微量重金属离子有较好的吸附效果,可作为重金属离子的吸附剂用于实验室重金属离子废水的处理。     

Influence of PEG coating on the oral bioavailability of gold nanoparticles in rats

Metallic nanoparticles can be produced in a variety of shapes, sizes, and surface chemistries, making them promising potential tools for drug delivery. Most studies to date have evaluated uptake of metallic nanoparticles from the GI tract with methods that are at best semi-quantitative. This study used the classical method of comparing blood concentration area under the curve (AUC) following intravenous and oral doses to determine the oral bioavailability of 1, 2 and 5?kDa PEG-coated 5?nm gold nanoparticles (AuNPs). Male rats were given a single intravenous dose (0.8?mg/kg) or oral (gavage) dose (8?mg/kg) of a PEG-coated AuNP, and the concentration of gold was measured in blood over time and in tissues (liver, spleen and kidney) at sacrifice. Blood concentrations following oral administration were inversely related to PEG size, and the AUC in blood was significantly greater for the 1?kDa PEG-coated AuNPs than particles coated with 2 or 5?kDa PEG. However, bioavailabilities of all of the particles were very low (相似文献   

Toxicity of arsenic species to Lemna gibba L. and the influence of phosphate on arsenic bioavailability

The toxicity of arsenic (As) species to Lemna gibba L. and the influence of PO(4) (3-) on As bioavailability and uptake were tested in batch culture. L. gibba were exposed to six test concentrations of NaHAsO(4). 7H(2)O and NaAsO(3), with 0, 0.0136, 13.6, and 40 mg L(-1) KH(2)PO(4). In batch culture As toxicity to L. gibba did not relate linearly to As concentration. The growth rate, related to frond number as recommended by OECD and ISO/DIN, was significantly inhibited in fronds exposed to 20-50 microg L(-1) As(III) compared with fronds exposed to As(V). The growth rate was stimulated when plants were exposed to 50-250 microg L(-1) of both As(III) and As(V). After exposure to 300-800 microg L(-1) growth inhibition was significantly higher for As(III) than for As(V), whereas above 800 microg L(-1) As(V) was inhibited the most. The bioaccumulation of As(III) and As(V) was significantly higher for P-deficient cultures (0.98 +/- 0.08 and 1.02 +/- 0.19 g kg(-1), respectively for 0.0136 mg L(-1) PO(4) (3-)) than for P-sufficient cultures (243 and 343 mg kg(-1) for 40 mg L(-1), respectively). Plants exposed to As(V) had uptake and accumulation values slightly higher than did plants exposed to As(III). No significant differences in bioaccumulation were found between plants exposed to a concentration of As(III) >1 mg L(-1) and those exposed to As(V) at the same concentration. This indicates a direct relationship to P content in the culture. Toxicity may result from the uptake of As(V) instead of PO(4) (3-) as a result of ion competition during uptake because of close thermodynamic properties, which may change the interaction among components in the media. The toxicity pattern is interpreted as a manifestation of changing speciation in the batch culture and of the oxidation of As(III) to As(V) in an oxygen-rich environment.