Human Biomonitoring of Environmental Chemicals among Elderly in Wuhan, China: Prioritizing Risks Using EPA's ToxCast Database.

In line with the "healthy aging" principle, we aim to assess the exposure map and health risks of environmental chemicals in the elderly. Blood samples from 918 elderly individuals in Wuhan, China, were analyzed using the combined gas/liquid-mass spectrometry technology to detect levels of 118 environmental chemicals. Cluster analysis identified exposure profiles, while risk indexes and bioanalytical equivalence percentages were calculated using EPA's ToxCast database. The detection rates for 87 compounds exceeded 70%. DEHP, DiBP, naphthalene, phenanthrene, DnBP, pyrene, anthracene, permethrin, fluoranthene, and PFOS showed the highest concentrations. Fat-soluble pollutants varied across lifestyles. In cluster 2, which was characterized by higher concentrations of fat-soluble substances, the proportion of smokers or drinkers was higher than that of nonsmokers or nondrinkers. Pesticides emerged as the most active environmental chemicals in peroxisome proliferator-activated receptor gamma antagonist, thyroid hormone receptor (TR) antagonist, TR agonist, and androgen receptor (AR) agonist activity assays. Additionally, PAEs and polycyclic aromatic hydrocarbons played significant roles as active contaminants for the corresponding targets of AR antagonists and estrogen receptor alpha. We proposed a list of priority pollutants linked to endocrine-disrupting toxic effects in the elderly, which may provide the groundwork for further research into environmental etiology.

POSS(epoxy)8 reinforced poly (butylene adipate-co-terephthalate)/lignin biodegradable films: Fabrication, enhanced mechanical properties and UV aging resistance.

To reduce the white pollution, the eco-friendly biodegradable poly (butylene adipate-co-terephthalate) (PBAT)-based films had attracted increasing interests worldwide. However, the high-cost of the PBAT had limited the large-scale development and application. In this work, 10 wt% low-cost lignin was introduced into the PBAT to prepare composite films by melt blending and blow molding, and the POSS(epoxy)8 was selected as the compatibilizer to improve the compatibility of PBAT and lignin. The maximum tensile strength and the nominal strain at break subsequently increased by 48.2 % and 21.4 % respectively, while the water vapor permeability enhanced by 9.9 %. Furthermore, the UV aging resistance of PBAT/lignin films were significantly improved, with only 1 wt% POSS(epoxy)8 content. This work provides an efficient strategy to foster the end-user confidence in the low-cost and eco-friendly biodegradable polymer materials with efficient performance.

Production of Gypenoside XVII from Ginsenoside Rb1 by Enzymatic Transformation and Their Anti-Inflammatory Activity In Vitro and In Vivo.

The enzymatic transformation of the sugar moiety of the gypenosides provides a new way to obtain more pharmacologically active components. A gene encoding a family 1 glycosyl hydrolase from Bifidobacterium dentium was cloned and expressed in Escherichia coli. The recombinant enzyme was purified, and its molecular weight was approximately 44 kDa. The recombinant BdbglB exhibited an optimal activity at 35 °C and pH 5.4. The purified recombinant enzyme, exhibiting ß-glucosidase activity, was used to produce gypenoside XVII (Gyp XVII) via highly selective and efficient hydrolysis of the outer glucose moiety linked to the C-3 position in ginsenoside Rb1 (G-Rb1). Under the optimal reaction conditions for large scale production of gypenoside XVII, 40 g ginsenoside Rb1 was transformed by using 45 g crude enzyme at pH 5.4 and 35 °C for 10 h with a molar yield of 100%. Furthermore, the anti-inflammatory effects of the product gypenoside XVII and its conversion precursor ginsenoside Rb1 were evaluated by using lipopolysaccharide (LPS)-induced murine RAW 264.7 macrophages and the xylene-induced acute inflammation model of mouse ear edema, respectively. Gypenoside XVII showed improved anti-inflammatory activity, which significantly inhibited the generation of TNF-α and IL-6 more effectively than its precursor ginsenoside Rb1. In addition, the swelling inhibition rate of gypenoside XVII was 80.55%, while the rate of its precursor was 40.47%, the results also indicated that gypenoside XVII had better anti-inflammatory activity than ginsenoside Rb1. Hence, this enzymatic method would be useful in the large-scale production of gypenoside XVII, which may become a new potent anti-inflammatory candidate drug.

The Performance Characterization and Optimization of Fiber-Optic Acoustic Pressure Sensors Based on the MOEMS Sensitized Structure.

In order to investigate the factors affecting the acoustic performance of the extrinsic Fabry-Perot interferometer (EFPI) fiber-optic acoustic pressure sensor and to effectively improve its detection capability, this paper enhances the sensor's detection sensitivity by adding more sensitized rings to its acoustic pressure-sensitive film. Furthermore, a novel real-time coupled acoustic test method is proposed to simultaneously monitor the changes in the spectral and acoustic metrics of the sensor to characterize its overall performance. Finally, an EFPI-type fiber-optic acoustic pressure sensor was developed based on the Micro-Optical Electro-Mechanical System (MOEMS). The acoustic tests indicate that the optimized fiber-optic acoustic pressure sensor has a sensitivity as high as 2253.2 mV/Pa, and the acoustic overload point (AOP) and signal-to-noise ratios (SNRs) can reach 108.85 dB SPL and 79.22 dB, respectively. These results show that the sensor produced through performance characterization experiments and subsequent optimization has a very high acoustic performance index, which provides a scientific theoretical basis for improving the overall performance of the sensor and will have broad application prospects in the field of acoustic detection.

Improving the sensitivity and selectivity of sulfonamides electrochemical detection with double-system imprinted polymers.

The extensive use of antibiotics leading to the rapid spread of antibiotic resistance poses high health risks to humans, but to date there is still lack of an on-site detection method of SA residues. In this study, we integrated radical polymerization using sodium p-styrenesulfonate as a functional monomer and the self-polymerization of dopamine to prepare double-system imprinted polymers (DIPs) using sulfonamide antibiotics as templates. We found that the DIPs were semi-interpenetrating polymer networks and introduction of poly(dopamine) improved the selectivity of the imprinted cavities as well as the conductivity. The selectivity and sensitivity of the sensor using DIPs were much higher than those using single-system MIPs. This sensor could determine sulfonamides in complex samples in the presence of structural analogues. The linear range was from 0.01 to 10.00 µmol L-1 with a detection limit of 4.00 nmol L-1. Furthermore, based on the highly selective DIPs and statistics analysis, this method could be used for simultaneous analysis of 4 sulfonamide types in real samples with an accuracy of 94.87 %. This work provides a strategy to improve the selectivity and sensitivity of MIPs based-sensor that can serve as tool for the simultaneous analysis of antibiotic residues in environment samples.

Specific nanoantibiotics for selective removal of antibiotic-resistant bacteria: New insights in bacterial imprinting based on interfacial biomimetic mineralization.

Antibiotic resistance has been a worsening global concern and selective elimination of antibiotic-resistant bacteria (ARB) while retaining the co-existed beneficial bacteria has been essential in environmental protection, which having attracted considerable interest. In this work, by integrating the whole cell imprinting and epitope imprinting strategy, magnetic bacterial imprinted polymers (BIPs) towards ARB were synthesized with interfacial biomimetic mineralization followed by a screening process. The binding data showed that the BIPs owned highly specific affinity towards the target bacteria. Taking advantage of this specific binding ability of BIPs, a two-step selective antimicrobial approach was developed. Remarkably, the BIP nanoantibiotics (nAbts) could efficiently destroy ARB without harming the beneficial bacteria. In comparison with the non-bacterial imprinted polymers, the biocompatible BIP nAbts showed a 12.5-fold increase in the survival percentage for the beneficial bacteria in wastewater. To the best of our knowledge, this is the first time that bacterial imprinting via interfacial biomimetic mineralization was developed, and also the first report of killing ARB without harming the beneficial bacteria in wastewater. We believe that this strategy provides a new insight into the design of novel affinity materials for the selective elimination of ARB in biological treatment for environmental protection.

Circ_0007099 upregulates GNG7 to function as a tumor inhibitor in gastric carcinoma by interacting with miR-425-3p.

Background: Circular RNAs (circRNAs) are usually dysregulated in human tumors and affect the malignant progression of tumors. Circ_0007099 is known to be downregulated in gastric carcinoma (GC), and this research was performed to investigate the regulatory function of circ_0007099 in GC progression. Methods: The detection of circ_0007099, miR-425-3p, and G protein γ subunit 7 (GNG7) was performed via reverse transcription-quantitative polymerase chain reaction assay. Cell proliferation was determined by EdU and colony formation assays, and angiogenesis was assessed via a tube formation assay. Glucose metabolism was evaluated with commercial kits, and protein expression was measured by western blot. Dual-luciferase reporter and RNA immunoprecipitation assays were performed to validate the target interaction. An in vivo exploration of circ_0007099 was conducted using a xenograft tumor assay. Results: Circ_0007099 was downregulated in GC patients and cells. Overexpression of circ_0007099 repressed cell proliferation, angiogenesis, and glucose metabolism while enhancing apoptosis in GC cells. Circ_0007099 exhibited a sponge effect on miR-425-3p, and the anti-tumor function of circ_0007099 was achieved by sponging miR-425-3p. Furthermore, miR-425-3p directly targeted GNG7, and miR-425-3p inhibition suppressed malignant progression by reducing GNG7 expression in GC cells. Circ_0007099 sponged miR-425-3p to upregulate the level of GNG7. We also found that in vivo tumor growth was reduced by circ_0007099 mediating the miR-425-3p/GNG7 axis. Conclusions: This study demonstrated that circ_0007099 inhibits the malignant behavior of GC cells by binding to miR-425-3p, thus regulating the expression of GNG7.

ZIF-8/nitrogen-doped reduced graphene oxide as thin film microextraction adsorbents for simultaneous determination of novel halogenated flame retardants in crayfish-aquaculture water systems.

Novel halogenated flame retardants (HFRs) have attracted much attention due to their environmental hazard and adverse effects on human health. In this study, a sensitive and simultaneous method for the determination of six novel HFRs was developed, including tetrabromobisphenol A (TBBPA), tetrachlorobisphenolA, TBBPA bis(2-hydroxyethyl ether), TBBPA bis(allyl ether), TBBPA bis(2,3-dibromopropyl ether) and 2,4,6-tris(2,4,6-tribromophenoxy)-1,3,5-triazine. ZIF-8 modified nitrogen-doped reduced graphene oxide (ZIF-8@N-rGO) was synthesized and coated onto a syringe filter to prepare a thin film microextraction (TFME) device. The adsorption capacities of ZIF-8@N-rGO for novel HFRs ranged from 50.98 to 112.84 mg g-1, exhibiting good extraction efficiency through a combination of π-π, hydrophobic, and hydrogen bonding interactions. The TFME device was coupled to a high-performance liquid chromatography-ultraviolet detection system to simultaneously determine target HFRs in crayfish-aquaculture water systems. Under the optimal extraction parameters, the linearities ranged from 0.1 to 100 ng mL-1. The method detection limits ranged from 0.030 to 0.14 ng mL-1 and relative recoveries ranged from 88.6 to 106.2%. We found that novel HFRs were detected in water and crayfish samples and were primarily distributed in the viscera and head shell of the crayfish. The bioconcentration factors ranged from 0.25 to 19.20 L kg-1, indicating non-bioaccumulation in the crayfish. This study provides valuable technology and information for potential health risks of exposure to novel HFRs from consuming crayfish.

Identification of hub genes and functional modules in colon adenocarcinoma based on public databases by bioinformatics analysis.

BACKGROUND: Colon adenocarcinoma (COAD) is one of the most common cancers in the world. Although an extensive effort has been made to elucidate its pathogenesis, the underlying molecular mechanisms and genetic characteristics remain elusive. METHODS: In this study, protein-coding transcript expression profiles of COAD were downloaded from the Cancer RNA-Seq Nexus (CRN) database. They were then integrated to identify the overlapping transcripts expressed in every COAD RNA sequencing (RNA-seq) subset. The functional annotation of these overlapping genes (OLGs) involved noting their biological process (BP), cellular components (CC), molecular function (MF) for Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway in the Database for Annotation, Visualization and Integrated Discovery (DAVID). Protein-protein interaction (PPI) networks were then constructed and analyzed using Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) and Cytoscape 3.8.2. RESULTS: A total of 10 hub genes and 3 functional modules were screened by the plugin cytoHubba and MCODE, respectively. The plugin ClueGO and DAVID were used for the functional enrichment analyses of both hub genes and modules. The expression of hub genes was verified through the gene expression profiling interactive analysis (GEPIA) database. Survival analysis of the hub genes revealed that low expressions of ADCY5, GNG2, and PTPRC were significantly associated with an improved COAD prognosis. Furthermore, the expression level of ADCY5 in stages I/II was lower than that in stages III/IV, which seems to explain why the low expression of ADCY5 results in a better prognosis. CONCLUSIONS: The identification of hub genes, functional modules, and pathways have the potential to improve our understanding of the causes and underlying molecular events of COAD. The hub gene ADCY5 could also be a prognostic monitoring indicator or therapeutic target in the treatment of COAD.

Molecularly imprinted polymer-capped wrinkled silica-quantum dot hybrid particles for fluorescent determination of tetra bromo bisphenol A.

A fluorescent probe has been developed for tetra bromo bisphenol A (TBBPA) detection based on molecularly imprinted polymers (MIPs) combined with wrinkled silica nanoparticles (WSNs) and CdTe quantum dot (QD) hybrid particles. The WSNs with large pore sizes were employed as a structural support platform for QD embedding, and MIPs were synthesized on the surface of QD-embedded WSNs. The synthetic procedure was characterized using transmission electron microscopy, Brunauer-Emmett-Teller measurements, X-ray photoelectron spectrometry, Fourier transform infrared spectroscopy, and zeta potential analysis. The MIP-capped wrinkled silica-QD hybrid particles (WSNs-QDs-MIPs) possessed an adsorption capacity of 96.5 mg g-1 with an imprinting factor of 7.9 towards TBBPA. Under the optimum incubation conditions, the fluorescence intensity (λex = 340 nm, λem = 605 nm) was quenched in proportion to added TBBPA in the range 0.025 to 5 µM with a limit of detection of 5.4 nM. The developed probe was successfully applied to the detection of TBBPA in plastic electronic waste samples and the results of this method agreed with those obtained using high-performance liquid chromatography. This method presented a satisfactory selectivity, stability, and reproducibility indicating its potential as a promising probe for TBBPA detection.

Simultaneous fluorescence determination of bisphenol A and its halogenated analogs based on a molecularly imprinted paper-based analytical device and a segment detection strategy.

Bisphenol A (BPA) and its halogenated analogs tetrabromobisphenol A (TBBPA) and tetrachlorobisphenol A (TCBPA) are common environmental contaminants and a method for their simultaneous determination is urgently needed. A paper-based analytical device (PAD) was prepared using a metal-organic framework of UiO-66-NH2 coated with molecularly imprinted polymers (MIPs) using TBBPA as a template. The maximum adsorption capacity was 120.94 mg g-1 and the imprinting factor was 4.07. The selective recognition ability of this PAD enabled the effective separation of TBBPA, TCBPA and BPA based on paper chromatography. Subsequently, the PAD cut into segments were used individually to determine the presence of target chemicals using a highly sensitive fluorescent method. Under ultraviolet light irradiation, UiO-66-NH2 acts as a photocatalyst to produce reactive oxygen species (ROS) that degrade TBBPA, TCBPA or BPA in the imprinted cavities and the fluorescent signal of 2',7'-dichlorodihydrofluorescein diacetate (H2DCFDA) added as a ROS probe enabled the indirect determination of target chemicals. This method could determine BPA and its halogenated analogs in dust samples simultaneously with detection limits ranging from 0.14 to 0.30 ng g-1. The intraday relative standard deviation (RSD) was ≤6.8% and interday RSD was ≤8.1%. The recoveries ranged from 91.0 to 105.6% with RSD values that were ≤7.5%. The results stemmed from this method were consistent with those obtained from LC-MS/MS. It is an environmentally-friendly approach due to the degradation of target pollutants and possesses many advantages such as high selectivity, low cost and easy-to-fabrication.

HIV-1 viral cores enter the nucleus collectively through the nuclear endocytosis-like pathway.

It is recognized that HIV-1 capsid cores are disassembled in the cytoplasm, releasing their genomes into the nucleus through nuclear pores, but there is also evidence showing the capsid (CA) exists in the nucleus. Whether HIV-1 enters the nucleus and how it enters the nucleus through the undersized nuclear pore remains mysterious. Based on multicolor labeling and real-time imaging of the viral and cellular components, our observations via light and electron microscopy suggest that HIV-1 selectively gathered at the microtubule organization center (MTOC), leading the nearby nuclear envelope (NE) to undergo deformation, invagination and restoration to form a nuclear vesicle in which the viral particles were wrapped; then, the inner membrane of the nuclear vesicle ruptured to release HIV-1 into the nucleus. This unexpected discovery expands our understanding of the complexity of HIV-1 nuclear entry, which may provide new insights to HIV-1 virology.

Accurate assessment of parabens exposure in healthy Chinese female adults: Findings from a multi-pathway exposure assessment coupled with intervention study.

Exposure of humans to parabens is widespread and urinary parabens are widely used as exposure biomarkers. However, are the levels of these chemicals suitable to assess exposure to parabens? We conducted an intervention study by controlling the use of personal care products (PCPs) to explore the exposure of parabens. Ten female participants were recruited who were treated with different types of PCPs during the 18-day study period. The concentrations of parabens and their metabolites in matrices of different exposure pathways (dust, drinking water and dietary food) and urine samples were determined. We demonstrated that PCPs were the major sources of parabens, accounting for >99% of total exposure. The metabolites were nonspecific to individual parabens and could not be used as exposure biomarkers. Urinary paraben concentrations were positively correlated with external exposure levels. However, poor reproducibility was observed, with intraclass correlation coefficients (ICC) ranging from 0.125 to 0.295 in unadjusted urinary concentrations. Creatinine-adjusting could not significantly improve the ICC values in random spot samples. After adjusting for both creatinine and kinetic models, the ICC values ranged from 0.695 to 0.886, indicating a good reproducibility. So, toxicokinetic parameters may be taken into consideration for precise monitoring of exposures for the non-persistent pollutants.

Optimizing interfacial adhesion in PBAT/PLA nanocomposite for biodegradable packaging films.

Biodegradable films poly(butylene adipate-co-butylene terephthalate) (PBAT)/poly(lactic acid) (PLA) incorporated with nano-polyhedral oligomeric silsesquioxane (POSS(epoxy)8) as a reactive compatibilizer were developed by melt processing. Structural, morphological, mechanical, and gas permeability properties of the films were determined. 1H NMR and GPC demonstrated that the POSS(epoxy)8 was chemically bound at the PBAT/PLA boundary phase via an epoxide ring opening reaction. SEM micrographs of impact fracture surfaces demonstrated the POSS(epoxy)8 improved interfacial adhesion between PBAT and PLA matrix. The mechanical properties of the PBAT/PLA films containing POSS(epoxy)8 were enhanced relative to pristine PBAT/PLA films. The water vapor, CO2 and O2 permeability of the PBAT/PLA films were improved by POSS(epoxy)8 addition. PBAT/PLA films containing POSS(epoxy)8 were shown to be superior to pristine PBAT/PLA films and polyethylene films in food storage tests. Results suggest that POSS(epoxy)8 addition during PBAT/PLA film production offers a simple strategy for the production of high performance biodegradable plastic packaging films.

Structure-Directed Screening and Analysis of Thyroid-Disrupting Chemicals Targeting Transthyretin Based on Molecular Recognition and Chromatographic Separation.

Exposure to thyroid-disrupting chemicals (TDCs) poses a great threat to human health. However, the screening and analysis of TDCs in environmental samples remain a tough work. In this study, we reported a structure-directed strategy for analyzing TDCs targeting transthyretin (TTR) based on molecular imprinting and chromatographic separation. The imprinted composites were prepared using l-thyroxine (T4) as a template and a tryptophan-like monomer screened from the amino acid library. The imprinted composites exhibited an adsorption capacity of 22.2 µmol g-1 for T4 and an imprinting factor of 2.1. Chromatographic testing was then conducted among 72 chemicals using the imprinted composites-packed column. High retention factors were observed for chemicals that were structurally similar to T4. The chromatographic results were compared with a data set of 45 chemicals with known activities toward TTR. The results suggested that chemicals can be distinguished as TTR binders and nonbinders by retention factors, with a predictive accuracy of more than 90%. Moreover, the retention factors of chemicals were highly correlated with the reported relative potencies obtained from TTR assays. Thus, screening of TTR-binding chemicals can be realized through this simple chromatographic method. The imprinted composites were applied for target analysis and nontarget analysis of TTR-binding chemicals in dust samples. Three new TTR binders were successfully identified and verified by this method. The combination of molecular imprinting and chromatography opens up a new approach for screening TDCs targeting TTR.

Colorimetric determination of tetrabromobisphenol A based on enzyme-mimicking activity and molecular recognition of metal-organic framework-based molecularly imprinted polymers.

A sol-gel method is presented to synthesize molecularly imprinted polymers (MIPs) composed with a copper-based metal-organic framework (referred to as MIP/HKUST-1) on a paper support to selectively recognize tetrabromobisphenol A (TBBPA). The imprinting factor is 7.6 and the maximum adsorption capacity is 187.3 mg g-1. This is much better than data for other MIPs. The degradation of TBBPA is introduced in the procedure. Due to the selective recognition by the MIP, the enzyme-mimicking properties of HKUST-1 under the MIP layer became weak due to the decrease of residue imprinted cavities. And adsorbed TBBPA can be degraded under consumption of hydrogen peroxide (H2O2). The combined effect of H2O2 and HKUST-1 cause the coloration caused by catalytic oxidation of 3,3',5,5'-tetramethylbenzidine to become less distinct. This amplification strategy is used for the ultrasensitive and highly selective colorimetric determination of TBBPA. The gray intensity is proportional to the logarithm concentration of TBBPA in the range of 0.01-10 ng g-1. The limit of detection is as low as 3 pg g-1, and the blank intensities caused by TBBPA analogues are <1% of that caused by TBBPA at the same concentration, this implying excellent selectivity. The spiked recoveries ranged from 94.4 to 106.6% with relative standard deviation values that were no more than 8.6%. Other features include low costs, rapid response, easy operation and on-site testing. Graphical abstractSchematic representation of colorimetric determination of tetrabromobisphenol A (TBBPA) by paper-based metal-organic framework-based molecularly imprinted polymers (MIP/HKUST-1 composites) using 3,3',5,5'-tetramethylbenzidine (TMB) as a substrate.

Electrochemical determination of tetrabromobisphenol A in water samples based on a carbon nanotubes@zeolitic imidazole framework-67 modified electrode.

Carbon nanotubes@zeolitic imidazole framework-67 (CNTs@ZIF-67), a conductive composite was prepared from carboxylic carbon nanotubes and a cobalt-imidazole framework. It possesses an excellent adsorption capacity (92.12 mg g-1) for the flame retardant tetrabromobisphenol A (TBBPA). The composite was characterized by transmission and scanning electron microscopy, FTIR and X-ray diffractometry. It was then used to modify an acetylene black electrode. Electrochemical studies showed the current response of the modified electrode to be larger than that of electrodes modified with CNTs-COOH or ZIF-67 only. Electrochemical impedance spectroscopy showed this material combination to improve the conductivity of ZIF-67. The addition of perfluorodecanoic acid further improves the response. The sensor is stable, reproducible, and has a linear range of 0.01-1.5 µM TBBPA concentration, with a 4.2 nM detection limit (at S/N = 3). The sensor was successfully applied to the detection of TBBPA in spiked rain and pool water samples.

Coiled molecularly imprinted polymer layer open-tubular capillary tube for detection of parabens in personal care and cosmetic products.

Personal care and cosmetic products (PCPs) are the primary exposure pathway of humans to parabens and their safety has become a public concern. However, sample pretreatment of PCPs is a great challenge due to their complexities and diversity. In this study, epoxide modified molecularly imprinted polymers (MIPs) were synthesized using ethylparaben as a template, methacrylic acid and isobutyl vinyl ether as co-monomers and glycidilmethacrylate as a post-modified monomer. MIP layer open-tubular tubes were prepared by modifying branched polyethylenimine and then grafting MIPs onto the inner surface of Teflon capillary tubes. The tube was coiled to effectively increase mass transfer and coupled to an HPLC-UV system for parabens detection in PCPs. Matrix interference was significantly decreased while efficient enrichment and recoveries were obtained. Under optimized conditions, the linear range for parabens detection was 0.5-600 ng mL-1 with detection limits of 0.2 to 0.3 ng mL-1. The system was used to study the contents of parabens in popular PCPs. The concentrations of parabens in 108 PCPs ranged from <0.5 ng g-1 to 2856 µg g-1 with geometric mean of 250.3 µg g-1. Almost all of the products contained at least one kind of parabens; methyl paraben (geometric mean: 182.9 µg g-1) and n-propyl paraben (geometric mean: 42.5 µg g-1) were the predominant compounds had been found in the samples. This method could be useful for human exposure assessment towards parabens.

Mediation of the relationship between phthalate exposure and semen quality by oxidative stress among 1034 reproductive-aged Chinese men.

BACKGROUND: Emerging evidence from animals indicates that oxidative stress plays a crucial role in the effects of phthalate exposure on male reproductive dysfunctions, which has never been thoroughly explored in humans. OBJECTIVE: To explore the potential mediating role of oxidative stress in the association of phthalate exposure with semen quality among 1034 Chinese men. METHOD: Repeated urine samples gathered from the male partners of sub-fertile couples were analyzed for 3 oxidative stress markers [8-hydroxy-2-deoxyguanosine (8-OHdG), 8-iso-prostaglandin F2α (8-isoPGF2α) and 4-hydroxy-2-nonenal-mercapturic acid (HNE-MA)], using a liquid chromatography-tandem mass spectrometry. Multivariate regression models were constructed to evaluate the associations of urinary oxidative stress markers with urinary phthalate metabolites and semen quality. We also explored the potential mediation effects by oxidative stress markers. RESULTS: Significantly positive dose-dependent relationships were observed between each individual phthalate metabolite and all analyzed oxidative stress markers (all p for trend<0.05), except for monoethyl phthalate (MEP) in relation to HNE-MA. Additionally, significantly or suggestively inverse dose-dependent relationships were exhibited between urinary 8-isoPGF2α and sperm concentration (p for trend = 0.05), and between urinary 8-OHdG and percent of normal sperm morphology (p for trend = 0.01). Mediation analysis showed that urinary 8-isoPGF2α suggestively mediated 12% of the inverse association between monobutyl phthalate (MBP) and sperm concentration, and that urinary 8-OHdG suggestively mediated 32% of the inverse association of MEP with percent of normal sperm morphology (both p < 0.10). CONCLUSIONS: Although further investigations are required, our results suggest that oxidative stress may play a mediating role in the effects of phthalate exposure on impaired semen quality.