Multi-pathway exposure assessment of organophosphate flame retardants in a southern Chinese population: Main route identification with compound-specificity.

In this study, we conducted comprehensive organophosphorus flame retardant (PFR) exposure assessments of both dietary and non-dietary pathways in a rural population in southern China. Skin wipes were collected from 30 volunteers. Indoor and outdoor air (gas and particles), dust in the houses of these volunteers, and foodstuffs consumed by these volunteers were simultaneously collected. The total PFR concentrations in dust, gas, and PM2.5 varied from 53.8 to 5.14 × 105 ng/g, 0.528 to 4.27 ng/m3, and 0.390 to 16.5 ng/m3, respectively. The forehead (median of 1.36 × 103 ng/m2) and hand (median of 920 ng/m2) exhibited relatively high PFR concentrations, followed by the forearm (median of 440 ng/m2) and upper arm (median of 230 ng/m2). The PFR concentrations in the food samples varied from 0.0700 to 10.9 ng/g wet weight in the order of egg > roast duck/goose and vegetable > pork > chicken > fish. Tris(1-chloro-isopropyl) phosphate (TCPP) was the main PFR in the non-diet samples, whereas the profiles of PFR individuals varied by food type. Among the multiple pathways investigated (inhalation, dermal exposure, dust ingestion, and food ingestion), dermal absorption and dust ingestion were the predominant pathways for tris(2-chloroethyl) phosphate (TCEP) and bisphenol A-bis(diphenyl phosphate) (BDP), respectively, whereas dietary exposure was the most important route for other chemicals.

Newly Detected Transmission of blaKPC-2 by Outer Membrane Vesicles in Klebsiella Pneumoniae.

OBJECTIVE: The prevalence of carbapenem-resistant Klebsiella pneumoniae (CR-KP) is a global public health problem. It is mainly caused by the plasmid-carried carbapenemase gene. Outer membrane vesicles (OMVs) contain toxins and other factors involved in various biological processes, including ß-lactamase and antibiotic-resistance genes. This study aimed to reveal the transmission mechanism of OMV-mediated drug resistance of Klebsiella (K.) pneumoniae. METHODS: We selected CR-KP producing K. pneumoniae carbapenemase-2 (KPC-2) to study whether they can transfer resistance genes through OMVs. The OMVs of CR-KP were obtained by ultracentrifugation, and incubated with carbapenem-sensitive K. pneumoniae for 4 h. Finally, the carbapenem-sensitive K. pneumoniae was tested for the presence of blaKPC-2 resistance gene and its sensitivity to carbapenem antibiotics. RESULTS: The existence of OMVs was observed by the electron microscopy. The extracted OMVs had blaKPC-2 resistance gene. After incubation with OMVs, blaKPC-2 resistance gene was detected in sensitive K. pneumoniae, and it became resistant to imipenem and meropenem. CONCLUSION: This study demonstrated that OMVs isolated from KPC-2-producing CR-KP could deliver blaKPC-2 to sensitive K. pneumoniae, allowing the bacteria to produce carbapenemase, which may provide a novel target for innovative therapies in combination with conventional antibiotics for treating carbapenem-resistant Enterobacteriaceae.

Comparative in vitro metabolism of short chain chlorinated paraffins (SCCPs) by human and chicken liver microsomes: First insight into heptachlorodecanes.

Short chain chlorinated paraffins (SCCPs) are emerging persistent organic pollutants of great concern due to their ubiquitous distribution in the environment. However, little information is available on the biotransformation of SCCPs in organisms. In this study, a chlorinated decane: 1, 2, 5, 5, 6, 9, 10-heptachlorodecanes (HeptaCDs) was subjected to in vitro metabolism by human and chicken liver microsomes at environmentally relevant concentration. Using ultra-performance liquid chromatography-Q-Exactive Orbitrap mass spectrometry, two metabolites: monohydroxylated hexachlorodecane (HO-HexCD) and monohydroxy heptachlorodecane (HO-HeptaCD) were detected in human liver microsomal assays, while only one metabolite (HO-HexCD) was identified in chicken liver microsomal assays. The formation of HO-HexCD was fitted to a Michaelis-Menten model for chicken liver microsomes with a Vmax (maximum metabolic rate) value of 4.52 pmol/mg/min. Metabolic kinetic parameters could not be obtained for human liver microsomes as steady state conditions were not reached under our experimental conditions. Notwithstanding this, the observed average biotransformation rate of HeptaCDs was much faster for human liver microsomes than for chicken liver microsomes. Due to the lack of authentic standards for the identified metabolites, the detailed structure of each metabolite could not be confirmed due to the possibility of conformational isomers. This study provides first insights into the biotransformation of SCCPs, providing potential biomarkers and enhancing understanding of bioaccumulation studies.

Evaluation of root-knot nematode disease control and plant growth promotion potential of biofertilizer Ning shield on Trichosanthes kirilowii in the field

Abstract Biofertilizer Ning shield was composed of different strains of plant growth promotion bacteria. In this study, the plant growth promotion and root-knot nematode disease control potential on Trichosanthes kirilowii in the field were evaluated. The application of Ning shield significantly reduced the diseases severity caused by Meloidogyne incognita, the biocontrol efficacy could reached up to 51.08%. Ning shield could also promote the growth of T. kirilowii in the field by increasing seedling emergence, height and the root weight. The results showed that the Ning shield could enhance the production yield up to 36.26%. Ning shield could also promote the plant growth by increasing the contents of available nitrogen, phosphorus, potassium and organic matter, and increasing the contents of leaf chlorophyll and carotenoid pigment. Moreover, Ning shield could efficiently enhance the medicinal compositions of Trichosanthes, referring to the polysaccharides and trichosanthin. Therefore, Ning shield is a promising biofertilizer, which can offer beneficial effects to T. kirilowii growers, including the plant growth promotion, the biological control of root-knot disease and enhancement of the yield and the medicinal quality.

Characteristics and health risk assessment of heavy metals exposure via household dust from urban area in Chengdu, China.

To investigate the characteristics of heavy metals (Cr, Cd, Pb, Zn, Cu and Ni) in household dust in urban household environment of Chengdu, China, 90 household dust samples were collected from 6 districts of the city. The information of houses and residents were also recorded during dust sampling to identify the correlations between heavy metals in household dust and the house attributes. And also the principal component analysis and cluster analysis for sources and impactor factors. The concentrations of Pb (123mg·kg-1), Zn (675mg·kg-1), Cu (190mg·kg-1), Cr (82.7mg·kg-1), Cd (2.37mg·kg-1) and Ni (52.6mg·kg-1) in household dust are in low or moderate levels when compare with that from other counties or areas. The heavy metals of household dust samples from Chengdu is higher concentrations than that in the street dust from Chengdu, except for Cr. Statistical analysis result showed traffic sources and corrosion of alloys are important factors contributing to the rise concentrations of heavy metals in household dust. In addition, there is negative correlation (p<0.05) between the heavy metals concentrations and floor levels. The ingestion is the important pathway for Pb, Zn, Cu and Ni via household dust exposure to the residents, and the dermal contact was identified as a main route for Cr and Cd in household dust exposure to the residents. There are minor non-carcinogenic and carcinogenic risks from the heavy metals in household dust for the residents in Chengdu.

Evaluation of root-knot nematode disease control and plant growth promotion potential of biofertilizer Ning shield on Trichosanthes kirilowii in the field.

Biofertilizer Ning shield was composed of different strains of plant growth promotion bacteria. In this study, the plant growth promotion and root-knot nematode disease control potential on Trichosanthes kirilowii in the field were evaluated. The application of Ning shield significantly reduced the diseases severity caused by Meloidogyne incognita, the biocontrol efficacy could reached up to 51.08%. Ning shield could also promote the growth of T. kirilowii in the field by increasing seedling emergence, height and the root weight. The results showed that the Ning shield could enhance the production yield up to 36.26%. Ning shield could also promote the plant growth by increasing the contents of available nitrogen, phosphorus, potassium and organic matter, and increasing the contents of leaf chlorophyll and carotenoid pigment. Moreover, Ning shield could efficiently enhance the medicinal compositions of Trichosanthes, referring to the polysaccharides and trichosanthin. Therefore, Ning shield is a promising biofertilizer, which can offer beneficial effects to T. kirilowii growers, including the plant growth promotion, the biological control of root-knot disease and enhancement of the yield and the medicinal quality.

An improved strategy for stable biocontrol agents selecting to control rice sheath blight caused by Rhizoctonia solani.

Rice sheath blight caused by Rhizoctonia solani Kühnis increasingly threatening rice production in China. DNA fingerprints of 220 R. solani strains isolated in 11 provinces of China were established by random amplified polymorphic DNA (RAPD)-PCR. Cluster analysis of strains isolated from the same region showed high similarity, indicating that the genetic diversity of R. solani strains is significantly related to geographical origin. We assessed potential bio-control abilities of bio-control agents (BCAs) by values according to inhibition zones against R. solani, extracellular hydrolytic enzymes activity and siderophores production in vitro. Fourteen strains with diverse expected bio-control potential were tested for their bio-control efficacy against rice sheath blight caused by 11 pathogenic exemplars and for growth promoting ability, separately. Bio-control efficacy of single bacterium against various R. solani strains differed significantly (-36.23%∼88.24%), while Pseudomonas fluorescens 4aYN11 achieved a relatively stable control efficacy of 32.26%-78.79% and growth promotion of 18.43%. Pearson correlation coefficient between bio-control efficacy of each BCAs and their assessment is 0.717. In the present study, we established an improved strategy for screening stable bio-control agents based on an assessment system, their growth promotion potential and phylogenetic diversity of pathogen R. solani, and the result provides us not only one promising bio-control strain 4aYN11 with an average bio-control efficacy of 56.50%, but also a practical way for future screen of novel BCAs.

Pollution characteristics and risk assessment of human exposure to oral bioaccessibility of heavy metals via urban street dusts from different functional areas in Chengdu, China.

Urban street dusts were collected in commercial area (CA), traffic area (TA), educational area (EA), residential area (RA) and parks area (PA) of Chengdu, China, to investigate the concentrations of heavy metals (Pb, Zn, Cu, Ni, Cd and Cr), and analyzed to evaluated possible sources and health risk assessment. The average concentrations (mg/kg) of Pb (82.3), Zn (296), Cu (100), Cd (1.66) and Cr (84.3) in urban street dusts were all higher than the local soil background values. The concentrations of heavy metals in each functional area could be classified as follows: CA>TA>RA>EA>PA. Principal component analysis and Cluster analysis showed mainly derived from the mixed sources of nature and traffic (51.7%). The results of health risk assessment showed no non-carcinogenic and carcinogenic risks of the metals for inhabitants. However, higher concentrations and oral bioaccessibility of the heavy metals in the dusts from CA and TA, indicating there was more health risks to the inhabitants in than that in other functional areas.

[Study on chlorinated disinfection byproducts and the relevant health risk in tap water of J City].

J City lies in the downstream of Taihu Lake and its water source was micro-polluted by the well-developed industry and agriculture inside the city and in the upper stream. Tap water of J City is characterized as high concentrations of organics and ammonia nitrogen, and chlorinated disinfection byproducts (CDBPs), which has drawn many public concerns for the health risk. Tap water was sampled in May, August, October of 2012 and January of 2013. Four trihalomethanes (THMs) and five haloacetic acids (HAAs) were determined with the gas chromatography. Results revealed that THMs accounted for 88.1% of the sum of THMs and HAAs, with higher concentrations in May, August and January (39.34, 50.37 and 28.02 microg x L(-1), respectively) while obviously lower in October (19.19 microg x L(-1)), which were significantly higher than that of HAAs (2.58-4.02 microg x L(-1)). After boiled for three minutes, THMs were removed over 92.3% but HAAs were largely increased. The health risk of CDBPs was then calculated based on the health risk assessment model recommended by the USEPA. The health risk caused by carcinogenic CDBPs was within a range of 3.1 x 10(-6) - 7. 3 x 10(-6) in the tap water, all over the recommended level of 1 x 10(-6), but after boiled, the value significantly decreased to 7.9 x 10(-7), which is below the recommended level. The health risk caused by non-carcinogenic CDBPs absolutely increased from 2.1 x 10(-11) to 3.4 x 10(-9) after boiled, which is below the reference value of 10(-5).

[Mechanism of membrane fouling and filtration characteristics in a membrane bioreactor for industrial wastewater treatment].

The influence of mixed liquor suspended solids (MLSS), soluble microbial product (SMP), extracellular polymeric substance (EPS), colloidal particles and other factors contributed to membrane fouling was analyzed in this pilot test by membrane bioreactor (MBR) process for the leather printing and dyeing industrial park mixed wastewater treatment. The results showed that slight membrane fouling occurred after 120-day experiment with an observable increase in membrane resistance R20 from 1.5 x 10(12) m(-1) to 1.8 x 10(12) m(-1). Also, a linear correlation was found between the proportion of colloidal particles concentration in TOC of MBR former solution and membrane filtration resistance change. However, the change of MLSS, SMP, EPS and other factors was not correlated with the membrane filtration resistance change. Therefore, the colloidal particle was considered to be the main factor causing membrane fouling, which attached to the membrane surface and deposited to block the membrane pore.

Molecular epidemiology of HCV monoinfection and HIV/HCV coinfection in injection drug users in Liuzhou, Southern China.

BACKGROUND: Hepatitis C virus (HCV) mono-infection and HCV/HIV (human immunodeficiency virus) co-infection are growing problems in injection drug users (IDU). Their prevalence and genotypic patterns vary with geographic locations. Access to harm reduction measures is opening up opportunities for improving the HIV/HCV profiling of IDU in China, where IDUs account for a significant proportion of the two infections especially in the southern part of the country. METHODOLOGY/PRINCIPAL FINDINGS: A cross sectional study was conducted. Through the Liuzhou Methadone Clinic, a total of 117 injection drug users (IDUs) were recruited from Guangxi, Southern China. A majority of the IDUs (96%) were HCV antibody positive, of which 21% were HIV infected. Unlike HCV monoinfection, there was spatial heterogeneity in the distribution of HIV/HCV coinfection, the latter also characterized by a higher prevalence of needle-sharing. Phylogenetic analysis revealed that genotype 6a was predominant in the study population. There were shorter genetic distances among the 6a sequences compared to the other HCV subtypes-1a, 3a, and 3b. CONCLUSION/SIGNIFICANCE: The results suggested that HIV and HCV were introduced at around the same time to the IDU populations in Southern China, followed by their differential spread as determined by the biologic characteristics of the virus and the intensity of behavioural risk. This pattern is different from that in other South East Asian countries where HCV infections have probably predated HIV.