Qunfang Zhou

High levels of heavy metals in rice (Oryza sativa L.) from a typical E-waste recycling area in southeast China and its potential risk to human health

Very few studies have investigated the heavy metal contents in rice samples from a typical E-waste recycling area. In this study, 10 heavy metals (As, Ba, Cd, Co, Cr, Cu, Hg, Mn, Ni and Pb) in 13 polished rice and relevant hull samples, six relevant paddy soil samples were investigated. The geometric mean concentrations of Cd, Cu and Hg in soil samples were 1.19, 9.98 and 0.32 microg g(-1), respectively, which were 4.0, 2.0 and 1.1-folds of the maximum allowable concentration (MAC) (0.30, 50.00, 0.30 microg g(-1), respectively) for Chinese agricultural soils. The analyzed metal concentrations were significantly different between rice and relevant hull except for As, Cd and Hg (p<0.05). All metal concentrations, except for Co, in rice hull were higher than those in polished rice. The geometric mean of Pb in polished rice reached 0.69 microg g(-1), which was 3.5-folds higher than the MAC (0.20 microg g(-1)) by the safety criteria for milled rice. Cd contents in 31% of the rice samples exceeded the national MAC (0.20 microg g(-1)), and the arithmetic mean also slightly exceeded national MAC. In addition, Cd and Pb contents in local rice were much higher than commercial rice samples examined in this work and previous studies. Comparing the tolerable daily intakes given by FAO/WHO with the mean estimated daily intakes; Pb daily intake through rice consumption in this area was 3.7 microg day(-1)kg(-1) body weight (bw), which already exceeded the FAO tolerable daily intake, and the Cd daily intake (0.7 microg day(-1)kg(-1) bw) through rice had already taken up 70% of the total tolerable daily intake (1 microg day(-1)kg(-1) bw). The daily intake of Hg and As through rice was much lower than the tolerable daily intakes, but bioaccumulation of Hg through the food chain and intake of As from other food stuff should also be of concern.

Effects of waterborne nano-iron on medaka (Oryzias latipes) : antioxidant enzymatic activity, lipid peroxidation and histopathology

Toxicity tests were performed to investigate possible harmful effects on medaka exposed to nano-iron. Dose-dependent decreases of superoxide dismutase (SOD) and increases of malondialdehyde (MDA) were induced in the medaka embryo, suggesting that oxidative damage was induced by nano-iron. For adult medaka, the disturbance of antioxidative balance was observed during the early exposure period based on the monitoring of the hepatic and cerebral SOD and reduced glutathione (GSH). No terminal oxidative damage occurred during the whole exposure period, probably due to the high self-recovering capability of the adult fish. Some histopathological and morphological alterations (cell swelling, hyperplasia, and granulomas, etc.) were observed in gill and intestine tissues, which confirmed that deleterious effects occurred as a result of direct contact with nano-iron. It is suggested that further evaluation should be made concerning the risk assessment of waterborne nano-iron on aquatic life.

Effects of silver nanoparticles on the development and histopathology biomarkers of Japanese medaka (Oryzias latipes) using the partial-life test

Silver nanoparticles (AgNPs) have emerged as an important class of nanomaterials and are currently used in a wide range of industrial and commercial applications. This has caused increasing concern about their effects on the environment and to human health. Using Japanese medaka (Oryzias latipes) at early-life stages as experimental models, the developmental toxicity of silver nanoparticles was investigated following exposure to 100-1000 μg/L homogeneously dispersed AgNPs for 70 days, and developmental endpoints were evaluated by microscopy during embryonic, larval and juvenile stages of development in medaka. Meanwhile, histopathological changes in the larval eye were evaluated. Retarded development and reduced pigmentation were observed in the treated embryos by AgNPs at high concentrations (≥ 400 μg/L). Maximum width of the optic tectum, as an indicator of midbrain development, decreased significantly in a dose-related manner. Furthermore, silver nanoparticles exposure at all concentrations induced a variety of morphological malformations such as edema, spinal abnormalities, finfold abnormalities, heart malformations and eye defects. Histopathological observations also confirmed the occurrence of abnormal eye development induced by AgNPs. The data showed non-linear or U-shaped dose-response patterns for growth retardation at 5 days of postfertilization, as well as the incidence of abnormalities. Preliminary results suggested that the developmental process of medaka may be affected by exposure to silver nanoparticles. Morphological abnormalities in early-life stages of medaka showed the potential developmental toxicities of silver nanoparticles. Further research should be focused on the mechanisms of developmental toxicity in fish exposed to silver nanoparticles.

Organotin pollution in China: an overview of the current state and potential health risk.

In recent years, considerable amounts of organotin compounds have entered the environment due to the wide industrial applications in China. Organotins were found in various environmental media. An overview of organotin contamination and distribution in China from various environmental samples, including waters and sediments, is presented to better understand the current state of organotin pollution in China and to improve environmental monitoring and management of organotin contamination. Exposure to organotin contaminated water and sediments induces accumulation of organotins in molluscs and biological effects such as imposex. Potential harmful effects on human health may also result from consumption of contaminated seafoods. Detailed information on distribution, impacts and assessment of risk to human health and marine ecosystems is discussed and monitoring of TBT using biomarkers is described. This review highlights the serious organotin contamination of coastal cities in China and emphasizes the need for long-term monitoring and the development of an effective regulatory program.

Elemental selenium particles at nano-size (Nano-Se) are more toxic to Medaka (Oryzias latipes) as a consequence of hyper-accumulation of selenium: A comparison with sodium selenite

Recent studies have shown that elemental selenium particles at nano-size (Nano-Se) exhibited comparable bioavailability and less toxicity in mice and rats when compared to sodium selenite, selenomethinine and methylselenocysteine. However, little is known about the toxicity profile of Nano-Se in aquatic animals. In the present study, toxicities of Nano-Se and selenite in selenium-sufficient Medaka fish were compared. Selenium bioaccumulation and subsequent clearance in fish livers, gills, muscles and whole bodies were examined after 10 days of exposure to Nano-Se and selenite (100 microg Se/L) and again after 7 days of depuration. Both forms of selenium exposure effectively increased selenium concentrations in the investigated tissues. Surprisingly, Nano-Se was found to be more hyper-accumulated in the liver compared to selenite with differences as high as sixfold. Selenium clearance of both Nano-Se and selenite occurred at similar ratios in whole bodies and muscles but was not rapidly cleared from livers and gills. Nano-Se exhibited strong toxicity for Medaka with an approximately fivefold difference in terms of LC(50) compared to selenite. Nano-Se also caused larger effects on oxidative stress, most likely due to more hyper-accumulation of selenium in liver. The present study suggests that toxicity of nanoparticles can largely vary between different species and concludes that the evaluation of nanotoxicology should be carried out on a case-by-case basis.

Silver Nanoparticle Exposure Attenuates the Viability of Rat Cerebellum Granule Cells through Apoptosis Coupled to Oxidative Stress

The impact of silver nanoparticles (AgNPs) on the central nervous system is a topic with mounting interest and concern and the facts remain elusive. In the current study, the neurotoxicity of commercial AgNPs to rat cerebellum granule cells (CGCs) and the corresponding molecular mechanism are closely investigated. It is demonstrated that AgNPs induce significant cellular toxicity to CGCs in a dose-dependent manner without damaging the cell membrane. Flow cytometry analysis with the Annexin V/propidium iodide (PI) staining indicates that the apoptotic proportion of CGCs upon treatment with AgNPs is greatly increased compared to the negative control. Moreover, the activity of caspase-3 is largely elevated in AgNP-treated cells compared to the negative control. AgNPs are demonstrated to induce oxidative stress, reflected by the massive generation of reactive oxygen species (ROS), the depletion of antioxidant glutathione (GSH), and the increase of intracellular calcium. Histological examination suggests that AgNPs provoke destruction of the cerebellum granular layer in rats with concomitant activation of caspase-3, in parallel to the neurotoxicity of AgNPs observed in vitro. Taken together, it is demonstrated for the first time that AgNPs substantially impair the survival of primary neuronal cells through apoptosis coupled to oxidative stress, depending on the caspase activation-mediated signaling.

Permission to enter cell by shape: nanodisk vs nanosphere.

Changing polystyrene nanoparticles from three-dimensional spherical shape to two-dimensional disk shape promotes their cell surface binding with significant reduction of cell uptake. As a result of lower cell uptake, nanodisks show very little perturbations on cell functions such as cellular ROS generation, apoptosis and cell cycle progression compared to nanospheres. Therefore, disk-shaped nanoparticles may be a promising template for developing cell membrane-specific and safer imaging agents for a range of biomedical applications such as molecular imaging, tissue engineering, cell tracking, and stem cell separation.

Silver nanoparticles cause oxidative damage and histological changes in medaka (Oryzias latipes) after 14 days of exposure

Silver nanoparticles (AgNPs) can exert negative effects on cell lines and embryos of freshwater fish. However, information on their distribution and long-term toxicity in adult species is limited. In the present study, a subchronic (14-d) toxicity test was designed to evaluate the bioaccumulation of AgNPs and their effects on the antioxidant defense system and histology of adult medaka. Purified AgNPs were well dispersed in water, and stability was maintained during the exposure period. After 14 d of exposure, a significant accumulation of Ag in the AgNP-dosed group was observed in the gill and intestinal tissues, with the highest levels found in the liver. Biochemical analysis indicated a dose-related decrease in the activity of lactate dehydrogenase and antioxidant enzymes in the liver, but not in the gills. However, dose-dependent increases in glutathione depletion and lipid peroxidation in the liver and gills were observed. Exposure to a graded dose of AgNPs also resulted in varying degrees of histological lesions in the tissues. Toxicological endpoints combined with metal distribution analysis suggested that AgNPs induced tissue-specific toxicity and that the liver is the organ most damaged by the Ag that might have been released from NPs. The oxidative damage caused by AgNPs may be associated with a large number of histological changes in the fish.

Determination of perfluorooctanesulfonate and perfluorooctanoic acid in sewage sludge samples using liquid chromatography/quadrupole time-of-flight mass spectrometry

A new method is developed for the determination of perfluorooctanesulfonate (PFOS) and perfluorooctanoic acid (PFOA) in sewage sludge samples. The analytes in sewage sludge samples are extracted by methanol and formic acid, cleaned by C18 solid-phase extraction, then separated, identified and quantitated by liquid chromatography/quadrupole time-of-flight mass spectrometry (LC-QTOF-MS). A C18 column (150 mm x 2.1 mm, 3.5 microm) with gradient elution of MeOH-H(2)O (60:40) containing 5 mmol/L ammonium acetate and MeOH-H(2)O (80:20) is used for the chromatographic separation. [M-K](-) ions at m/z 498.93 for PFOS and [M-COOH](-) ion at m/z 368.97 for PFOA are selected for QTOF-MS in the negative electrospray ionization mode. The detection limits for PFOS and PFOA in sewage sludge samples are 0.5 and 0.8 ng/g, respectively. The spiked recoveries are in the range of 85-114 and 71-98% for PFOS and PFOA, respectively. The proposed method is successfully applied to the analysis of PFOS and PFOA in 16 sewage sludge samples from China. PFOS and PFOA are detected in most sewage sludge samples and the concentrations of PFOS and PFOA are up to 5383 and 4780 ng/g (oven dry weight), respectively.

Dose- and time-related changes in aerobic metabolism, chorionic disruption, and oxidative stress in embryonic medaka (Oryzias latipes): underlying mechanisms for silver nanoparticle developmental toxicity.

Silver nanoparticles (AgNPs) are widely employed in commercial products, and are thus inevitably released into the aquatic environment. Many studies have indicated that AgNPs could induce toxicological effects on embryonic fish. To understand the mechanism of AgNP developmental toxicity, we determined the effects of AgNPs on the egg membrane, aerobic metabolism, antioxidant system, lipid peroxidation, as well as reactive oxygen species (ROS) and singlet oxygen ((1)O(2)) generation in early-life medaka fish (Oryzias latipes). AgNP treatment at 62.5-1000 μg/L caused significant increase in retarded development and abnormalities. Destruction of the surface ornamentation and egg envelope was observed at a higher AgNP concentration (≥125 μg/L) using light microscopy and scanning electron microscopy. A dose-dependent increase in lactate dehydrogenase activity, an indicator of anaerobic metabolism, and superoxide dismutase activity was observed in the treated embryos. In contrast, the total reduced glutathione level decreased. A high thiobarbituric acid reactive substance concentration was generated upon AgNP exposure from day 1 to day 7 postfertilisation. The biochemical parameters suggested that oxidative stress was induced by the AgNPs. Unexpectedly, a dose-dependent reduction in ROS and (1)O(2) generation upon high AgNP exposure (≥250 μg/L) was observed. Although the morphological damages induced by the AgNPs were irreversible, restorable antioxidant defenses were noted in the well-developed embryos. This finding supported the idea that the stage of morphogenesis and organogenesis is a critical window to chemical exposure or environmental stress. Overall, the results suggested that hypoxia, disturbed egg chorion, and oxidative stress are mechanistically associated with AgNP toxicity in embryonic fish.