Search

Uptake, transport and toxicity of engineered nanomaterials (ENMs) into plant cells are complex processes that are currently still not well understood. Parts of this problem are the multifaceted plant anatomy, and analytical challenges to visualize and quantify ENMs in plants. We critically reviewed the currently known ENM uptake, translocation, and accumulation processes in plants. A vast number of studies showed uptake, clogging, or translocation in the apoplast of plants, most notably of nanoparticles with diameters much larger than the commonly assumed size exclusion limit of the cell walls of ∼5–20 nm. Plants that tended to translocate less ENMs were those with low transpiration, drought-tolerance, tough cell wall architecture, and tall growth. In the absence of toxicity, accumulation was often linearly proportional to exposure concentration. Further important factors strongly affecting ENM internalization are the cell wall composition, mucilage, symbiotic microorganisms (mycorrhiza), the absence of a cuticle (submerged plants) and stomata aperture. Mostly unexplored are the roles of root hairs, leaf repellency, pit membrane porosity, xylem segmentation, wounding, lateral roots, nodes, the Casparian band, hydathodes, lenticels and trichomes. The next steps towards a realistic risk assessment of nanoparticles in plants are to measure ENM uptake rates, the size exclusion limit of the apoplast and to unravel plant physiological features favoring uptake. [ABSTRACT FROM PUBLISHER]

Abstract: Polychlorinated biphenyls (PCBs) can be metabolized to hydroxylated polychlorinated biphenyls (OH-PCBs) as reported in a number of animal studies. However, there are few studies on OH-PCBs in vivo in whole plants. In order to explore the formation of OH-PCBs in whole plants in detail, poplars (Populus deltoides × nigra, DN34) were exposed to 3,3′,4,4′-tetrachlorobiphenyl (CB77) in hydroponic solution. Poplars are widely used in phytoremediation applications and the complete genome has been sequenced. In this research, a HPLC-MS method was developed to directly determine the hydroxylated metabolites of CB77 (OH-CB77s), avoiding the experimental errors introduced by derivatization pretreatments required by gas chromatography-based methods. Three potential hydroxylated metabolites of CB77, including 6-hydroxy-3,3′,4,4′-tetrachlorobiphenyl (6OH-CB77), 5-hydroxy-3,3′,4,4′-tetrachlorobiphenyl (5OH-CB77) and 4′-hydroxy-3,3′,4,5′-tetrachlorobiphenyl (4′OH-CB79), were determined in poplar tissues. The major product, 6OH-CB77, was detected in the roots, bottom bark, bottom wood, middle bark and middle wood for the whole poplar plants, but the minor product, 5OH-CB77, was detected only in the poplar roots. The concentration of 6OH-CB77 was about 10 times greater than that of 5OH-CB77 in the roots. However, the major mammalian metabolite, 4′OH-CB79 was not detected in any of the samples. The results suggest that the hydroxylated metabolic pathway of CB77 is via an epoxide intermediate in poplar. [ABSTRACT FROM AUTHOR]

Abstract: A novel on-line coupled HPLC–hydride generation (HG)–ICP/MS system was developed for rapid, direct and sensitive speciation of methyltins in seawater without any pretreatment step. Methyltin compounds were separated by reversed phase HPLC, and then on-line reacted with potassium borohydride and acetic acid to generate volatile hydride products. The volatile derivatization products were separated in the spray chamber of ICP/MS and then introduced into ICP/MS by argon gas for detection. Monomethyltin (MMT), dimethyltin (DMT) and trimethyltin (TMT) were baseline separated in less than 15min by reversed phase HPLC. The influence of KBH4 concentration and type of acid on the system performance was investigated and optimized. Calibration curves, based on peak heights against concentration, were linear in the range of 0.5–50ng (Sn) mL−1 of methyltins with correlation coefficients of 0.9990, 0.9990 and 0.9996 for MMT, DMT and TMT, respectively. The relative standard deviations measured at 10ng (Sn) mL−1 for these three methyltins were in the range of 0.6–1.4% (n =5), and the calculated detection limits (S/N=3) for MMT, DMT and TMT were 0.266, 0.095 and 0.039ng (Sn) mL−1, respectively. This method was successfully applied to the speciation of methyltins in seawater with spiked recovery in the range of 95.4–106.9%. MMT and DMT were detected in all the seawater samples with concentrations in the range of 1.0–1.5 and 0.30–0.57ng (Sn) mL−1 for MMT and DMT, respectively. [Copyright &y& Elsevier]

The photodegradation of methyltins, as environmental pollutants, has scarcely been studied so far because of the shortage of rapid and sensitive speciation methods, even though they have very simple structures. The photodegradation of monomethyltin trichloride (MMT), dimethyltin dichloride (DMT) and trimethyltin chloride (TMT) was studied with our new developed HPLC-FPD hyphenated system, which enables rapid and sensitive detection of methyltins. The half-life times and kinetic rate constants of their degradation at different pH were calculated. The results suggest that MMT, DMT and TMT can be degraded under the UV irradiation rapidly at different pH, with a degradation rate sequence of TMT [Copyright &y& Elsevier]

Hormonally active compounds may move with agricultural runoff from fields with applied manure and biosolids into surface waters where they pose a threat to human and environmental health. Riparian zone plants could remove hormonally active compounds from agricultural runoff. Therefore, sorption to roots, uptake, translocation, and transformation of 3 estrogens (17β-estradiol, 17α-ethinylestradiol, and zeranol) and 1 androgen (trenbolone acetate) commonly found in animal manure or biosolids were assessed by hydroponically grown hybrid poplar, Populus deltoides x nigra, DN-34, widely used in riparian buffer strips. Results clearly showed that these hormones were rapidly removed from 2 mg L-1 hydroponic solutions by more than 97% after 10 d of exposure to full poplar plants or live excised poplars (cut-stem, no leaves). Removals by sorption to dead poplar roots that had been autoclaved were significantly less, 71% to 84%. Major transformation products (estrone and estriol for estradiol; zearalanone for zeranol; and 17β-trenbolone from trenbolone acetate) were detected in the root tissues of all 3 poplar treatments. Root concentrations of metabolites peaked after 1 d to 5 d and then decreased in full and live excised poplars by further transformation. Metabolite concentrations were less in dead poplar treatments and only slowly increased without further transformation. Taken together, these findings show that poplars may be effective in controlling the movement of hormonally active compounds from agricultural fields and avoiding runoff to streams. Environ Toxicol Chem 2015;34:2906-2913. © 2015 SETAC [ABSTRACT FROM AUTHOR]

BACKGROUND: Because of the vital importance of the proteasome pathway, chemicals affecting proteasome activity could disrupt essential cellular processes. Although the toxicity of organotins to both invertebrates and vertebrates is well known, the essential cellular target of organotins has not been well identified. We hypothesize that the proteasome is a molecular target of environmental toxic organotins. OBJECTIVES: Our goal was to test the above hypothesis by investigating whether organotins could inhibit the activity of purified and cellular proteasomes and, if so, the involved molecular mechanisms and downstream events. RESULTS: We found that some toxic organotins [e.g., triphenyltin (TPT)] can potently and preferentially inhibit the chymotrypsin-like activity of purified 20S proteasomes and human breast cancer cellular 26S proteasomes. Direct binding of tin atoms to cellular proteasomes is responsible for the observed irreversible inhibition. Inhibition of cellular proteasomes by TPT in several human cell lines results in the accumulation of ubiquitinated proteins and natural proteasome target proteins, accompanied by induction of cell death. CONCLUSIONS: The proteasome is one of the molecular targets of environmental toxic organotins in human cells, and proteasome inhibition by organotins contributes to their cellular toxicity. [ABSTRACT FROM AUTHOR]

Recently, increasing regulatory and public attention has been paid to the exposure risks of antibiotics due to their occurrence and antibiotic resistance worldwide. However, limited information on antibiotic levels in general populations is available. Forty antibiotics, including 9 sulfonamides, 5 fluoroquinolones, 4 macrolides, 4 tetracyclines, 3 chloramphenicols, 12 β-lactams and 3 others, were analyzed in 107 serum samples of normal adults collected from a hospital in Dalian, North China, between 2015 and 2016 using solid-phase extraction (SPE) coupled with HPLC-MS/MS. The results clearly showed that antibiotics were present in the serum of these adults. Specifically, 28 antibiotics were detected in the samples, with detection frequencies ranging from 0.9% to 17.8%. The total antibiotic concentrations in 26.2% of the serum samples were between the LOD and 20.0 ng/mL. Importantly, the maximum concentrations of 5 antibiotics (trimethoprim, ciprofloxacin, cefaclor, lincomycin and erythromycin) were above 1000 ng/mL in 3.7% of the samples. Furthermore, the detection frequencies of 5 veterinary antibiotics, 7 human antibiotics and 16 human/veterinary antibiotics in the serum samples were 23.4%, 17.8% and 29.0%, respectively. Significant differences of the veterinary antibiotics between female and male adults and of the sulfonamides between different BMI (body mass index) groups were observed ( p < 0.05). The concentrations of sulfonamides in elderly individuals were significantly higher ( p < 0.05) than those in young people. Finally, our results showed that almost all of the adults had no health risks related to exposure to antibiotics at such levels despite the high effect ratio ( ER = 1.74) for azithromycin in one sample. This study is the first to report the current status of antibiotics in human blood, which can help in better understanding the long-term effects of antibiotics on general populations and in identifying susceptible populations that are at high risk to antibiotic exposure. [ABSTRACT FROM AUTHOR]

Seven polybrominated diphenyl ethers (PBDEs) and eleven hydroxylated PBDEs (OH-PBDEs) were selected to investigate their contamination status in 32 female serum samples from Dalian, China. These studied PBDEs and OH-PBDEs were found in most of the serum samples with the concentrations of ΣPBDEs and ΣOH-PBDEs ranging from 1.07 to 38.7ng/g lipid (median: 5.56ng/g lipid) and from 0.011 to 0.436ng/g lipid (median: 0.069ng/g lipid), respectively. More impressively, BDE-47 and OH-BDE-47 were the predominant congeners in female serum, accounting for 52% of ΣPBDEs and 46% of ΣOH-PBDEs, respectively. Correspondence analysis indicated that significant (p<0.05) positive correlations were observed between BDE-47 and its metabolites such as 6-OH-BDE-47, 3-OH-BDE-47 and 4'-OH-BDE-49. In addition, the positive significant (p<0.05) correlation was shown between ∑PBDEs and lipid contents but between concentrations of ∑PBDEs and ages or BMIs, as well as for ∑OH-PBDEs. [ABSTRACT FROM AUTHOR]

E-wastes in China are growing dramatically. Since 2009, the Chinese government has continuously issued a series of laws and regulations and established a preliminary e-waste management system based on extended producer responsibility (EPR) principles, so as to protect the environment and improve resource utilization. In this paper, effectiveness of current e-waste management in China is analyzed in detail from the government policy, enterprise and public awareness perspective. Government regulations and amendments of relevant policies, which are consistent with the status to promote the emergence and development of formal e-waste recycling enterprise, are introduced and examined. Chinese current e-waste recycling technology, capacity and equipment are discussed as well as the construction and operation of several leading enterprises and a national industrial park. Chinese people׳s awareness of e-waste hazards, disposal habits and participation in environmental initiatives are also surveyed to guide the future measures. Promoted by the efforts of the government, enterprises and citizens, Chinese e-waste management has been improving for the past six years and it continues to develop. Finally, potential remaining problems of e-waste management are examined and their possible solutions are proposed. [ABSTRACT FROM AUTHOR]

A recent challenge faced by China is to cope with the huge amount of waste electrical and electronic equipment (WEEE) being generated all over the country. With increased pressure of environmental protection and resource conservation, laws and regulations based on extended producer responsibility (EPR) principles have been enacted by the government to promote and support for developing formal WEEE recycling enterprises. While the WEEE management system is an extensive reverse logistics system involving consumers, collectors, dismantlers, recyclers, and even EEE producers and remanufacturers, any problem in every entity may hinder the effective operation of the whole system. This paper aims to demonstrate current status of WEEE treatment and to give suggestions for improving WEEE reutilization in China, as well as provide references for countries with similar experiences as China in WEEE recycling. The actual WEEE generation, collection and recycling situation along with public awareness on WEEE treatment are investigated in Zhejiang Province, China. The survey results show that although there is consensus in the hazards of WEEE among residents, a few of them can distinguish between formal (legal) channels and informal (illegal) ones to deal with WEEE and a considerable part of populations even choose informal collection channels. Furthermore, we present a model of WEEE reverse logistics system including private trader, second-hand store, retailer adopting “Old for New” activity, classified recovery station, informal recycling enterprise, formal recycling enterprise, etc., to observe practical operation of all the entities and their inter-relations in detail. We summarize some recommendations for the government, enterprises and consumers to promote WEEE treatment more efficiently in China. [ABSTRACT FROM AUTHOR]