Bioavailability of Lead to Juvenile Swine Dosed with Soil from the Smuggler Mountain NPL Site of Aspen, Colorado

Bioavailability of lead (Pb) has become an issue in quantifyingexposure of sensitive populations and, where necessary, establishingcleanup levels for contaminated soil. Immature swine were usedas a model for young children to estimate the degree to whichPb from two fully characterized composite samples from the SmugglerMountain Superfund Site in Aspen, Colorado may be bioavailableto resident children. The composite soils contained 14,200 and3870 µg Pb/g of soil. Relative and absolute enteric bioavailabilitiesof Pb in soil (oral dose groups of 75,225, and 675 µgPb/kg body wt/day) were estimated by comparison with an orallyadministered soluble Pb salt (lead acetate = PbAc₂·3H₂O)(dose groups of 0, 75, and 225 µg Pb/kg body wt/day) andan intravenously administered aqueous solution of Pb (100 µgPb/kg/day) from the same trihydrate salt administered dailyfor 15 days to 50 juvenile swine. The biological responses (areaunder the blood Pb concentration-time curve, and the terminalliver-, kidney-, and bone-lead concentrations) produced by Pbfrom PbAc₂·3H₂O and lead-contaminated soils were determined.This study revealed Pb from soil containing 14,200 µgPb/g of soil had a bioavailability relative to Pb from PbAc(RBA), ranging from 56% based on the area under the blood leadconcentration-time curve (AUC) versus dose, to 86% based oncalculations from liver- Pb loading versus dose. Similarly,Pb from soil containing 3870 µg Pb/g of soil had an RBAranging from 58% based on the AUC versus dose, to 74% basedon calculations from liver- and kidney- Pb loading versus dose.Bioavailability of Pb in soils may be more or less than EPA'sdefault RBA of 60%, therefore, measuring site- specific RBAsprovides a basis for improved exposure and risk assessment.     

An assessment of DDT and other chlorinated compounds and the reproductive success of American robins (Turdus migratonrius) breeding in fruit orchards

Although DDT was banned in the 1970s, American robins (Turdus migratorius) breeding in fruit orchards of the Okanagan Valley, British Columbia, continue to be contaminated with DDT and its metabolites. The objectives of our study were (1) to assess organochlorine (OC) contamination in robins breeding in Okanagan orchards (1993–1995, 1997–1998) and (2) to determine if exposure affected reproductive success when compared to robins from non-orchard habitat (lower mainland, British Columbia). Robins in orchards had total DDT egg residues of 48.64 mg/kg (geometric mean; n=92) while those in non-orchard habitat had 1.10 mg/kg (geometric mean; n=26), wet weight. The probability of nest survival during the incubation period was 96.7% (confidence interval: 95.7–97.5%; n=165) in orchard habitat and 96.7% (confidence interval: 94.6–98.1%; n=28) in non-orchard habitat. During the nestling period the probability of nest survival was 98.2% (confidence interval: 97.2–98.9%; n=123) in orchard habitat and 96.2% (confidence interval: 92.8–98.0%; n=34) in non-orchard habitat. Clutch (p<0.0001) and brood size (p=0.0133) were larger in orchards (n=150 and n=93, respectively) compared to non-orchard nests (n=42 and n=23, respectively) with no difference in fledge rate. DDE (r ²=0.11, p=0.0030, n=68) and dieldrin (r ²=0.29, p<0.0001, n=68) were negatively correlated with fledge rate in robin eggs collected from orchard habitat, however, low r ² values signify minimal biological significance. Although American robins nesting in Okanagan orchards are exposed to high OC levels, reproductive success does not appear to be negatively impacted.     

Ecotoxicity of riverbank spring water along the Hanford Reach,Columbia River

The purpose of this study was to evaluate potential ecotoxicity of riverbank springs along the Columbia River on the Hanford site where nuclear materials were historically produced. Water samples from seven springs were collected during 1994–1995. Bioassays were conducted with Pimephales promelas (fathead minnows) for survival and growth and with Ceriodaphnia dubia (daphnids) for survival and reproduction. Synoptic chemical data were used to supplement interpretation of bioassay results. Significant decreases (p<0.05) in survival were observed for two springs in both P. promelas and C. dubia at separate locations during 1994. Significant reductions (p<0.05) in C. dubia reproduction were found for six springs in 1994 and one in 1995. A stimulatory effect (p<0.05) was also observed for this endpoint at another spring in 1995. Reproduction was the most sensitive endpoint evaluated in terms of both number of adverse effects identified and test water concentration, while growth was the least sensitive endpoint. One or more toxicological benchmarks were equaled or exceeded for all riverbank spring samples where toxicity was observed. For the contaminants evaluated, heavy metals (e.g., Cr, Cu, Ni, Zn) may have contributed to the observed toxicity. Despite limitations of employing synoptic chemical data to supplement sample characterization and extrapolating laboratory bioassay data to the field, results of this study demonstrated ecotoxicity associated with several riverbank springs, presumably reflecting contamination of groundwater on the Hanford site. ©1999 John Wiley & Sons, Inc. Environ Toxicol 14: 473–480, 1999     

Persistence of cyclic peptide toxins in dried Microcystis aeruginosa crusts from lake Mokoan,Australia

Dried Microcystis aeruginosa Kuetzing emend. Elenkin crusts estimated to be 5–6 months old from the shore of Lake Mokoan were toxic by mouse bioassay (LD₁₀₀ 100–140 mg dry wt/kg mouse). Fresh bloom material from the lake was also highly toxic (LD₁₀₀ 25–35 mg dry wt/kg mouse). Microcystin high performance liquid chromatography (HPLC) profiles of the crust and fresh material were very similar, with 24 compounds having UV spectra consistent with microcystin LR. Five of the major microcystins were purified and analysed by electrospray/mass spectrometry. The molecular weights of these microcystins [910, 924, 982, 982 (two compounds), and 986] do not correspond with known microcystins. All five compounds were hepatotoxic to mice with LD₁₀₀ values ranging from 85 to 140 μg microcystin/kg mouse). Total microcystin contents (expressed as microcystin LR aquivalents) determined by HPLC correlated with the mouse bioassay analyses (crust 2.1 μg microcystin/mg dry wt; fresh 4.1 μg microcystin/mg dry wt). These results suggest that microcystin is protected from degradation while encapsulated within the dried Microcystis crusts. Leaching experiments demonstrated that re-wetting of the crust material leads to rapid release of microcystins into the surrounding water. These observations have important management implications for lakes and reservoirs where crusts of cyanobacterial material form on the shoreline. © by John Wiley & Sons, Inc.     

Quinolone-induced arthropathy: exposure of magnesium-deficient aged rats or immature rats, mineral concentrations in target tissues and pharmacokinetics

Quinolone treatment or magnesium deficiency induce identical cartilage lesions in juvenile rats and show additive arthropathogenic effects. It has been shown previously that neither condition is arthropathogenic in 8-week-old rats. Joint cartilage from aged individuals is rather prone to pathological alterations but information on prolonged quinolone treatment and/or dietarily induced magnesium deficiency in aged animals is not available. We treated magnesium-deficient (n = 9) aged Wistar rats (age 15 months) and age-matched controls with daily doses of 600 mg ofloxacin/kg body wt. by gastric intubation for 28 days. Further groups of magnesium-deficient and control rats (n = 9 and n = 10, respectively) received the vehicle only. Peak plasma concentrations of ofloxacin in adult rats were 20.5 ± 5.6 mg/l (mean ± SD) following treatment with a single dose of 600 mg/kg body wt. At the end of the experiment the degree of magnesium deficiency was most pronounced in plasma (Mg²⁺-def., 0.33 ± 0.12 mmol/l; control, 0.97 ± 0.08 mmol/l) and less pronounced in sternal cartilage (Mg²⁺-def., 10.8 ± 3.6 mmol/kg dry wt; control, 13.3 ± 2.8 mmol/kg dry wt), whereas the magnesium concentration in femoral bone remained unchanged (Mg²⁺-def., 201 ± 13 mmol/kg dry wt; control, 204 ± 11 mmol/kg dry wt). Histological investigation of the knee joints revealed no cartilage lesions following ofloxacin treatment, magnesium deficiency or a combination of both conditions. By contrast, cartilage lesions such as scars and erosions of the joint surface, chondrocyte clusters within acellular areas of the cartilage matrix and persisting clefts were detectable in knee joints from 7 of 10 adult rats (age 9 months) which had been treated with 4 × 600 mg fleroxacin/kg body wt. at 5 weeks of age. Mean plasma concentration of fleroxacin in juvenile rats was approx. 50 mg/l between 1.5 and 6 h after dosing and the drug was still detectable in plasma 48 h after dosing (0.4 ± 0.1 mg/l). Our data indicate that joint cartilage in aged rats is not altered by a 4-week quinolone treatment, even during magnesium deficiency. Cartilage lesions in adult rats were only detectable if the animals had been treated during the sensitive phase at 5 weeks postnatally. Received: 3 March 1997 / Accepted: 15 May 1997     

Toxicity of selenate and selenite to the potworm <Emphasis Type="Italic">Enchytraeus albidus</Emphasis> (Annelida: Enchytraeidae): a laboratory test

Little information is available about the toxicity of inorganic selenium forms in soil animals. Therefore, the effects of selenate and selenite on the mortality and reproduction of Enchytraeus albidus were examined in standard laboratory tests with chronic exposure. Total and available amount of selenate and selenite were tested in a calcareous loamy chernozem soil. The LC₅₀ of selenate was 5.69 (2.7–8.12) mg kg^-1 dry wt. for total Se and 4.74 (2.14–6.98) mg kg^-1 dry wt. for available Se. Selenite LC₅₀ was as high as 22.5 (19.6–25.7) mg kg^-1 dry wt. for total Se and 8.10 (6.8–9.6) mg kg^-1 dry wt. for available Se. The EC₅₀ of selenate was 0.41 (0.35–0.48) mg kg^-1 dry wt. for total Se and 0.28 (0.24–0.34) mg kg^-1 dry wt. for available Se. Selenite EC₅₀ was as high as 7.3 (6.2–8.5) mg kg^-1 dry wt. for total Se and 2.46 (2.05–2.91) mg kg^-1 dry wt. for available Se. The response in reproduction was more sensitive to Se toxicity than the response in mortality. Selenate proved to be more toxic than selenite. Available data show that E. albidus may function as a biological indicator for some inorganic selenium forms in the soil.     

Cadmium toxicity for terrestrial invertebrates: taking soil parameters affecting bioavailability into account

Acute and chronic ecotoxicity tests with cadmium were conducted with the earthworm Eisenia fetida, the potworm Enchytraeus albidus and the springtail Folsomia candida. To assess the influence of the soil type on cadmium bioavailability, these tests were carried out in a standard artificial soil, in a sandy and a loamy field soil. It was not possible to evaluate the influence of soil parameters on the bioavailability on the basis of the experiments that were conducted in only three different soil types, therefore, literature data were also included. However, even in the same standard artificial soils, toxicity data in the literature for Eisenia fetida and Folsomia candida varied considerably. Consequently, no models could be developed that allow a normalization of the ecotoxicity of cadmium to parameters controlling bioavailability. In contrast to zinc, effect concentrations of cadmium for terrestrial invertebrates were always much higher than background concentrations. As the effect of aging on the bioavailability of cadmium was never taken into account, because toxicity experiments were always carried out in freshly spiked soils, these effect concentrations may even be regarded as conservative. Furthermore, the zinc–cadmium ratio in soils is usually so high that the risk of zinc ecotoxicity for terrestrial invertebrates will usually be much greater in comparison to cadmium ecotoxicity.     

Quantity and quality of natural organic matter influence the ecotoxicity of titanium dioxide nanoparticles

Nanoparticles’ fate is amongst other parameters determined by the quantity and quality of natural organic matter (NOM). Consequently, the ecotoxicity of nanoparticles is modified, while only little information is available on the NOM characteristics triggering this interplay. This study systematically examined how NOM quantity and quality influences the acute ecotoxicity of titanium dioxide nanoparticles (nTiO₂) towards Daphnia magna. Therefore, two nTiO₂ products (A-100 and P25; ～100?nm) were investigated in combination with seven NOM types of variable quality at four levels each (up to 4.00?mg total organic carbon/L). The results showed that – independent of the applied nTiO₂ product and NOM type – nTiO₂ ecotoxicity decreased up to a factor of?>18 with increasing NOM concentration. More importantly, increasing levels of aromaticity and hydrophobicity of the NOM decreased the magnitude of toxic effects caused by nTiO₂, which was again independent of the nTiO₂ product tested. In the light of the ubiquitary presence of NOM, the ecotoxicological risk of nTiO₂ in surface waters with high NOM loads is likely moderate. However, interactions of nTiO₂ and NOM in combination with other natural or chemical stressors are not well-understood but seem to be fundamental for a reliable risk assessment of nanoparticles.     

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 lead on Na+, K+‐ATPase and hemolymph ion concentrations in the freshwater mussel Elliptio complanata

Freshwater mussels are an imperiled fauna exposed to a variety of environmental toxicants such as lead (Pb) and studies are urgently needed to assess their health and condition to guide conservation efforts. A 28‐day laboratory toxicity test with Pb and adult Eastern elliptio mussels (Elliptio complanata) was conducted to determine uptake kinetics and to assess the toxicological effects of Pb exposure. Test mussels were collected from a relatively uncontaminated reference site and exposed to a water‐only control and five concentrations of Pb (as lead nitrate) ranging from 1 to 245 μg/L in a static renewal test with a water hardness of 42 mg/L. Endpoints included tissue Pb concentrations, hemolymph Pb and ion (Na⁺, K⁺, Cl^?, Ca²⁺) concentrations, and Na⁺, K⁺‐ATPase enzyme activity in gill tissue. Mussels accumulated Pb rapidly, with tissue concentrations increasing at an exposure‐dependent rate for the first 2 weeks, but with no significant increase from 2 to 4 weeks. Mussel tissue Pb concentrations ranged from 0.34 to 898 μg/g dry weight, were strongly related to Pb in test water at every time interval (7, 14, 21, and 28 days), and did not significantly increase after day 14. Hemolymph Pb concentration was variable, dependent on exposure concentration, and showed no appreciable change with time beyond day 7, except for mussels in the greatest exposure concentration (245 μg/L), which showed a significant reduction in Pb by 28 days, suggesting a threshold for Pb binding or elimination in hemolymph at concentrations near 1000 μg/g. The Na⁺, K⁺‐ATPase activity in the gill tissue of mussels was significantly reduced by Pb on day 28 and was highly correlated with tissue Pb concentration (R² = 0.92; P = 0.013). The Na⁺, K⁺‐ATPase activity was correlated with reduced hemolymph Na⁺ concentration at the greatest Pb exposure when enzyme activity was at 30% of controls. Hemolymph Ca²⁺ concentration increased significantly in mussels from the greatest Pb exposure and may be due to remobilization from the shell in an attempt to buffer the hemolymph against Pb uptake and toxicity. We conclude that Na⁺, K⁺‐ATPase activity in mussels was adversely affected by Pb exposure, however, because the effects on activity were variable at the lower test concentrations, additional research is warranted over this range of exposures. © 2010 Wiley Periodicals, Inc. Environ Toxicol, 2012.     

Prevalence and associated demographic characteristics of exposure to multiple metals and their species in human populations: The United States NHANES, 2007–2012

Lead (Pb), cadmium (Cd), mercury (Hg), and arsenic (As) are among the top 10 pollutants of global health concern. Studies have shown that exposures to these metals produce severe adverse effects. However, the mechanisms underlying these effects, particularly joint toxicities, are poorly understood in humans. The objective of this investigation was to identify and characterize prevalent combinations of these metals and their species in the U.S. NHANES population to provide background data for future studies of potential metal interactions. Exposure was defined as urine or blood levels ≥ medians of the NHANES 2007–2012 participants ≥6 years (n = 7408). Adjusted-odds ratios (adj-OR) and 95% confidence intervals were determined for covariates (age, gender, and race/ethnicity, cotinine and body mass index). Species-specific analysis was also conducted for As and Hg including iAs (urinary arsenous acid and/or arsenic acid), met-iAs (urinary monomethylarsonic acid and/or dimethylarsinic acid), and oHg (blood methyl-mercury and/or ethyl-mercury). For combinations of As and Hg species, age- and gender-specific prevalence was determined among NHANES 2011–2012 participants (n = 2342). Data showed that approximately 49.3% of the population contained a combination of three or more metals. The most prevalent unique specific combinations were Pb/Cd/Hg/As, Pb/Cd/Hg, and Pb/Cd. Age was consistently associated with these combinations: adj-ORs ranged from 10.9 (Pb/Cd) to 11.2 (Pb/Cd/Hg/As). Race/ethnicity was significant for Pb/Cd/Hg/As. Among women of reproductive age, frequency of oHg/iAs/met-iAS and oHg/met-iAs was 22.9 and 40.3%, respectively. These findings may help prioritize efforts to assess joint toxicities and their impact on public health.     

Toxicity of abamectin to the terrestrial isopod <Emphasis Type="Italic">Porcellio</Emphasis> <Emphasis Type="Italic">scaber</Emphasis> (Isopoda,Crustacea)

To determine effects of the antiparasitic veterinary drug abamectin on the isopod Porcellio scaber, animals were exposed for 21 days to Lufa 2.2 soil spiked at concentrations of 3–300 mg/kg dry soil. After exposure, abamectin residues in the isopods were analysed using a novel analytical method. Toxicity was evaluated on different levels of biological organisation: biochemical, cellular and the individual organism. Measurements included glutathione S-transferase (GST) activity and stability of cell membranes in the digestive gland, animal mass gain or loss, food consumption, behaviour and mortality. LC50 for the effect of abamectin on survival of P. scaber was 71 mg/kg dry soil. The most obvious sublethal effects were reduced food consumption and decreased body mass (NOEC 3 mg/kg dry soil). Additionally, loss of digging activity and reduced GST activity (NOEC 30 mg/kg dry soil) and cell membrane destabilization (NOEC 10 mg/kg dry soil) were recorded. Abamectin only slightly accumulated in the isopods, with bioaccumulation factors always being <0.1. Based on these results and current information on environmental levels of abamectin, it is not likely that isopods will be affected by abamectin, but further studies with exposure through faeces are recommended.     

Environmental risk assessment for the polycyclic musks, AHTN and HHCB. II. Effect assessment and risk characterisation

Reports of the polycyclic musks AHTN and HHCB in surface water and fish, primarily in Europe, have prompted studies of their environmental effects. These effects then are used, along with the predicted environmental concentrations in a risk assessment according to the approach developed under European Union Regulation 793/93, in line with the Technical Guidance Document for risk assessment of new and existing chemicals. In 72-h studies with algae (Pseudokirchneriella subcapitata), NOECs were 0.374 mg/l (AHTN) and 0.201 mg/l (HHCB). In 21-day reproductive tests with daphnia (Daphnia magna) NOECs were 0.196 (AHTN) and 0.111 mg/l (HHCB). In 21-day growth tests with bluegill sunfish (Lepomis macrochirus), NOECs were 0.067 (AHTN) and 0.068 mg/l (HHCB). And, finally 35-day early life stage tests with fathead minnows (Pimephales promelas) resulted in NOECs of 0.035 (AHTN) and 0.068 mg/l (HHCB). These results lead to Predicted No Effect Concentrations (PNEC) of 3.5 microg/l (AHTN) and 6.8 microg/l (HHCB) for aquatic organisms. For the soil compartment, 8-week studies with earthworms (Eisenia fetida) resulted in NOECs of 105 (AHTN) and 45 mg/kg (HHCB) and 4-week studies with springtails (Folsomia candida) resulted in a NOECs of 45 mg/kg for both substances. These values lead to a PNEC of 0.32 mg/kg dw for both materials. Using mammalian studies, PNECs for fish or worm eating predators of 10 mg/kg fw (AHTN) and 100 mg/kg fw (HHCB) can be derived. For sediment dwelling organisms, PNECs were derived by equilibrium partitioning using the aquatic PNECs. Comparing PNECs with the measured or predicted environmental exposures leads to risk characterisation ratios as follows: aquatic species: AHTN 0.086, HHCB 0.074; sediment organisms: AHTN 0.44, HHCB 0.064; soil organisms: AHTN 0.091, HHCB 0.10; fish eating predators: AHTN 0.012, HHCB 0.001; worm eating predators: AHTN 0.007, HHCB 0.001.     

Antidiabetic,antioxidant, and TNF-α lowering properties of extract of the traditionally used plant Ixeris gracilis in alloxan-induced diabetic mice

Abstract

Context: Ixeris gracilis DC. Stebbins (Asteraceae) is a plant considered to be medicinal by local communities of Meghalaya, India.

Objective: To evaluate the antidiabetic potential, antioxidant activity, and effect of the 80% methanolic extract of the leaves of Ixeris gracilis on tumor necrosis factor-α (TNF-α) expression.

Materials and methods: Varying doses (250–1000?mg/kg body weight) were administered intraperitoneally to normoglycemic mice and their hypoglycemic properties noted for 24?h; the optimum dose observed was used to evaluate its antihyperglycemic activity and effect on glucose tolerance. In vitro antioxidant activity was analyzed by assessing the DPPH radicals scavenging ability of the extract and the total polyphenols, flavonoid, carbohydrate, and protein contents were determined. Diabetic mice were then subjected to daily intraperitoneal injections of the extract for 12 days after which the antioxidant enzyme activities in the tissues were assayed and serum TNF-α was evaluated by ELISA.

Results: The extract displayed varying hypoglycemic activity. The dose of 250?mg/kg body weight exhibited potent antihyperglycemic activity and improved glucose tolerance. The extract was able to scavenge free radicals (IC₅₀ 57.544?µg/ml) and contained polyphenol (76.269?±?0.204?mg GAE/g dry wt), flavonoid (70.070?±?0.626?mg rutin equivalent/g dry wt), protein (4.368?±?8.916?mg/g dry wt), and carbohydrate (558.189?±?0.002?mg/g dry wt). TNF-α level and overall activity of glutathione peroxidase and superoxide dismutase in the liver, kidney, and brain of extract-treated diabetic mice were improved.

Conclusion: The study supports the inclusion of Ixeris gracilis in the list of plants with antidiabetic potential.     

Lead toxicity in Brassica pekinensis Rupr.: effect on nitrate assimilation and growth

Lead is a major heavy-metal contaminant in the environment that has various anthropogenic and natural sources. To study the phytotoxic effects of Pb on the popular vegetable Chinese cabbage (Brassica pekinensis Rupr.) via depression of nitrogen assimilation, pot culture experiments with three concentrations of treatment with Pb (0, 4, and 8 mmol/kg dry soil) were carried out. Our results demonstrated adverse effects of Pb on nitrogen assimilation and plant growth. The addition of Pb in the soil resulted in elevated accumulation of Pb in the shoots of the plants: Pb concentrations of 14.3, 202.3, and 418.2 mg/kg (DW) in the shoots were detected with the 0, 4, and 8 mmol/kg treatments, respectively. Compared to the control, Pb exposure (4 and 8 mmol/kg) significantly decreased shoot nitrate content (71% and 80% of the control), nitrate reductase activity (104% and 49% of the control), and free amino acid content (81% and 82% of the control), indicating decreased nitrogen assimilation in the plants. The effect of Pb also was shown by the progressive decline in shoot biomass with increasing Pb concentration in plant shoots and in the soil. However, at the treatment levels used in this study, lead did not induce visible toxic symptoms. The lowest-concentration Pb treatment (4 mmol/kg) stimulated chlorophyll b content but did not influence chlorophyll a content. The results suggested that the toxicity of Pb to the plants occurred at least partly via depression of nitrogen assimilation.     

基于生物可给性和靶器官毒性剂量法的乌梢蛇中铅和砷联合暴露评估

目的 通过考察乌梢蛇Zaocys dhumnades（Cantor）中铅（Pb）和砷（As）的生物可给性,并探索靶器官毒性剂量（TTD）法在评估中药中重金属联合暴露风险中的应用,为限量标准的制定提供参考。方法 通过胃-肠两步模拟消化（in vitro PBET）联合电感耦合等离子体质谱（ICP-MS）法对乌梢蛇中Pb和As的生物可给性进行考察,根据其生物可给性计算其日暴露量。采用危害指数（HI）法对于Pb和As联合暴露产生的健康风险进行初步筛查;进一步针对不同毒理学终点,采用TTD法对Pb和As的累积风险进行更加精确的评估。结果 8批乌梢蛇中Pb和As的合格率为100%。HI法的初步评估结果表明,所有批次乌梢蛇中Pb和As的HI值均＜1。TTD法评估结果表明,作用终点心血管系统、神经系统、肾脏、血液和睾丸,所有批次乌梢蛇的HI值均＜1,健康风险可接受。结论 基于生物可给性,探索乌梢蛇中Pb和As的累积风险评估方法,为中药外源性有害残留物风险评估的方法开发提供新的思路,为制定更加科学的限量标准提供技术支撑。     

人工养殖赤子爱胜蚓中重金属及有害元素的测定

目的 建立人工养殖赤子爱胜蚓中铅、镉、砷、汞、铜含量测定的方法,并测定6批赤子爱胜蚓药材中铅、镉、砷、汞、铜的含量。方法 采用微波消解样品,用石墨炉原子吸收法测定铅、镉的含量;火焰原子吸收法测定铜的含量;原子荧光光谱法测定砷、汞含量。结果 铅的回收率为103.6%（RSD=6.4%）,镉的回收率在92.0%（RSD=7.7%）,铜的回收率在101.6%（RSD=8.1%）,砷的回收率在94.4%（RSD=4.7%）,汞的回收率在93.6%（RSD=5.4%）。结论 本方法操作简便、快速,且准确度和精密度高,适合于赤子爱胜蚓药材中铅、镉、铜、汞和砷的含量测定。     

In vitro and in vivo effects of lead,methyl mercury and mercury on inositol 1,4,5-trisphosphate and 1,3,4,5-tetrakisphosphate receptor bindings in rat brain

In vitro and in vivo effects of mercury (Hg), methyl mercury (MM) and lead (Pb) on [³H]inositol 1,4,5-trisphosphate (IP₃) and [³H]linositol 1,3,4,5-tetrakisphosphate (IP₄) receptor binding in the Sprague-Dawley rat brain cerebellar membranes were studied. In vitro studies indicate that binding of [³H]IP₃ and [³H]IP₄ to cerebellar membranes was inhibited by Hg while they were stimulated by MM or Pb in a concentration-ependent manner. MM was more potent (EC₅₀ 3,4 μM) than Pb (EC₅₀ 18.2 μM) in stimulating the [³H]IP₃ receptor binding activity whereas Pb (IC₅₀ 30 μM) was more potent than MM (IC₅₀ 133 μM) in stimulating the [³H]IP₄, receptor binding. When the rats were treated (i.p) with Hg (5 mg/kg body wt.) or MM (5 mg/kg body wt.) or Pb (25 mg/kg body wt.) for 3 or 24 h, no significant alterations in[³H]IP₃ receptor binding were observed in cerebellum and cerebral cortex. But the above treatment of Pb or MM for 3 or 24 h to rats resulted in an increase of [³H]IP₄ receptor binding in the membranes of cerebral cortex. However, the rats treated with Hg (1 mg/kg body wt./day) or Pb (25 mg/kg body wt./day) for 7 days did not show any alteration in binding of [³H]IP₃ to its receptors in cerebellar membranes but an increase in this receptor binding was noticed with the treatment of MM (2.5 mg/kg body wt./day) for 7 days. The cerebellum and cerebral cortex of rats with the above treatment of MM or Pb for 7 days exhibited an increase in [³H]IP₄ receptor binding. These in vitro and in vivo data suggest that alterations in inositol polyphosphate receptor binding by metals could result in alterations in intracellular calcium levels which may influence neuronal activity.     

Assessment of bioavailability and human health exposure risk to heavy metals in surface soils (Klang district,Malaysia)

In urban area surface soil the heavy metal concentrations followed the order: Pb (76.15?mg/kg) >?Fe (12.96?mg/kg)?>?Cu (11.58?mg/kg)?>?Al (10.3?mg/kg)?>?Zn (6.42?mg/kg)?>?Co (0.21?mg/kg) >?Cd (0.18?mg/kg)?>?Cr (0.07?mg/kg). For the industrial area surface soil, heavy metal concentrations followed the sequence: Pb (55.28?mg/kg)?>?Al (15.5?mg/kg)?>?Fe (14.73?mg/kg)>?Cu (14.68?mg/kg) >?Zn (4.48?mg/kg) >?Co (0.26?mg/kg) >?Cr (0.11?mg/kg)?>?Cd (0.11?mg/kg). PCA output showed that the first and second principal components are attributed due to the presence of “urban metals” in the urban areas while third principal component reflects the anthropogenic factor in the industrial areas. Total Cancer Risk values are more than the incremental lifetime (1.0E???05), showing the likelihood of a cancer threat for adults and children. For non-carcinogenic risks, Hazard Index values <1 one indicating no potential risks.