Organic photoelectrochemical transistor aptasensor for dual-mode detection of DEHP with CRISPR-Cas13a assisted signal amplification

Emerging organic photoelectrochemical transistors (OPECTs) with inherent amplification capabilities, good biocompatibility and even self-powered operation have emerged as a promising detection tool, however, they are still not widely studied for pollutant detection. In this paper, a novel OPECT dual-mode aptasensor was constructed for the ultrasensitive detection of di(2-ethylhexyl) phthalate (DEHP). MXene/In2S3/In2O3 Z-scheme heterojunction was used as a light fuel for ion modulation in sensitive gated OPECT biosensing. A transistor system based on poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) converted biological events associated with photosensitive gate achieving nearly a thousand-fold higher current gain at zero bias voltage. This work quantified the target DEHP by aptamer-specific induction of CRISPR-Cas13a trans-cutting activity with target-dependent rolling circle amplification as the signal amplification unit, and incorporated the signal changes strategy of biocatalytic precipitation and TMB color development. Combining OPECT with the auxiliary validation of colorimetry (CM), high sensitivity and accurate detection of DEHP were achieved with a linear range of 0.1 pM to 200 pM and a minimum detection limit of 0.02 pM. This study not only provides a new method for the detection of DEHP, but also offers a promising prospect for the gating and application of the unique OPECT.

Adsorption Characterization of Lactobacillus sp. for Di-(2-ethylhexyl) phthalate

Di-(2-ethylhexyl) phthalate (DEHP) is the widely detected plasticizer in foods whose exposure is associated with a myriad of human disorders. The present study focused on identifying Lactobacillus strains with high adsorption potential towards DEHP and further elucidating the mechanism of binding using HPLC, FTIR and SEM. Two strains, Lactobacillus rhamnosus GG and Lactobacillus plantarum MTCC 25,433, were found to rapidly adsorb more than 85% of DEHP in 2 h. Binding potential remained unaffected by heat treatment. Moreover, acid pre-treatment enhanced the DEHP adsorption. Chemical pre-treatments, such as NaIO4, pronase E or lipase, caused reduction in DEHP adsorption to 46% (LGG), 49% (MTCC 25,433) and 62% (MTCC 25,433), respectively, attributing it to cell wall polysaccharides, proteins and lipids. This was also corroborated by stretching vibrations of C = O, N-H, C-N and C-O functional groups. Furthermore, SDS and urea pre-treatment, demonstrated the crucial role of hydrophobic interactions in DEHP adsorption. The extracted peptidoglycan from LGG and MTCC 25,433 adsorbed 45% and 68% of DEHP, respectively, revealing the imperative role of peptidoglycan and its integrity in DEHP adsorption. These findings indicated that DEHP removal was based on physico-chemical adsorption and cell wall proteins, polysaccharides or peptidoglycan played a primary role in its adsorption. Owing to the high binding efficiency, L. rhamnosus GG and L. plantarum MTCC 25,433 were considered to be a potential detoxification strategy to mitigate the risk associated with the consumption of DEHP-contaminated foods.

Rice straw-derived chitosan-enhanced plasticizers as biologically and environmentally friendly alternatives for sustainable materials

Plasticizers like Bis(2-ethylhexyl)phthalate (DEHP) are commonly used to enhance plastic properties but pose environmental and health risks. This study successfully derived plasticizers X and Y from rice straws, demonstrating efficacy in chitosan polymer coatings. Chitosan-based polymers exhibit exceptional hardness, with a value of 300 MPa, due to their enriched structure and robust chitosan bonding. This surpasses the hardness of DEHP. Zebrafish exposure over 5 days revealed that X and Y had no significant behavioral impact, while DEHP caused noticeable toxic effects. Maternal DEHP exposure reduced placental cell growth, unlike X and Y, which had no adverse effects on uterine differentiation or placenta formation, suggesting their safety in human pregnancy. The successful development of X and Y represents a crucial step towards greener plasticizers, addressing environmental concerns and promoting safer alternatives in various industries.

GC-MS Analysis of Persicaria bistorta: Uncovering the Molecular Basis of Its Traditional Medicinal Use

Persicaria bistorta is a perennial herb used traditionally in treating various ailments, including diarrhea, abdominal pain, and bleeding. In this study, we used gas chromatography-mass spectrometry (GC-MS) analysis to identify the chemical composition of Persicaria bistorta. The GC-MS analysis revealed the presence of several compounds, including flavonoids, tannins, saponins, and alkaloids. Among those, the most important from medicinal points of view are ethyl oleate (3%), cyclotetradecane (4.74%), dodecanoic acid (4.69%), hexadecanoic acid (5.61%), tetradecane (5.25%), cis-13-octadecenoic acid (10.91%), and bis(2-ethylhexyl) phthalate (32%). The GC-MS analysis of ethanolic fraction of Persicaria bistorta involved in antibacterial activity showed about 18 compounds. Among those, the most important from a medicinal and nutritional point of view are bis(2-ethylhexyl) phthalate (42.20%), 6-octadecenoic acid methyl ester, (Z)- (10.37%), ethyl oleate (6.84%), hexadecanoic acid methyl ester (6.67%), and methyl ester and oleic acid (5.27%). Reported biological antibacterial activity has shown that the main compound determined in both extracts was bis(2-ethylhexyl) phthalate, which has higher peak area percentage in ethanolic extract than in ethyl acetate fraction. Some oily compounds important for health because of their cis-conformation were also revealed in the given study like ethyl oleate and oleic acid. Overall, results suggest that Persicaria bistorta may have therapeutic potential and warrant further investigation. Further research is needed to confirm the efficacy and safety of Persicaria bistorta as a natural medicine and determine its active compounds' mechanisms of action.

Remediation of di(2-ethylhexyl) phthalate (DEHP) contaminated black soil by freeze-thaw aging biochar

Di(2-ethylhexyl) phthalate (DEHP), a complex structure with high toxicity, is a common organic pollutant. This study investigated the effects of fresh biochar (FBC), and freeze-thaw cycled aged biochar (FTC-BC) on DEHP-contaminated soils using a pot experiment. The specific surface area of FBC increased from 145.20 to 303.50 m2/g, and oxygen-containing functional groups increased from 1.26 to 1.48 mol/g after freeze-thaw cycles, greatly enhancing the adsorption of DEHP by biochar in the soil. The comprehensive radar chart evaluation showed that FBC and FTC-BC reduced DEHP growth stress and improved the soil properties. Compared with FBC, FTC-BC performed better in protecting the normal growth of pakchoi and improving soil properties. In addition, the application of biochar increased the diversity and abundance of bacteria in the DEHP-contaminated soil and changed the composition of the soil bacterial community. The partial least squares path model (PLS-PM) showed that adding biochar as a soil remediation agent significantly positively impacted soil nutrients and indirectly reduced the DEHP levels in soil and plants by increasing soil microbial diversity. Compared with FBC, FTC-BC creates a more satisfactory living environment for microorganisms and has a better effect on the degradation of DEHP in the soil. This study provides a theoretical basis for future biochar remediation of DEHP-contaminated soils in cold high-latitude regions.

Inhibitory effects of phthalate esters (PAEs) and phthalate monoesters towards human carboxylesterases (CESs)

Phthalate esters (PAEs), accompanied by phthalate monoesters as hydrolysis metabolites in humans, have been widely used as plasticizers and exhibited disruptive effects on the endocrine and metabolic systems. The present study aims to investigate the inhibition behavior of PAEs and phthalate monoesters on the activity of the important hydrolytic enzymes, carboxylesterases (CESs), to elucidate the toxicity mechanism from a new perspective. The results showed significant inhibition on CES1 and CES2 by most PAEs, but not by phthalate monoesters, above which the activity of CES1 was strongly inhibited by DCHP, DEHP, DiOP, DiPP, DNP, DPP and BBZP, with inhibition ratios exceeding 80%. Kinetic analyses and in vitro-in vivo extrapolation were conducted, revealing that PAEs have the potential to disrupt the metabolism of endogenous substances catalyzed by CES1 in vivo. Molecular docking results revealed that hydrogen bonds and hydrophobic contacts formed by ester bonds contributed to the interaction of PAEs towards CES1. These findings will be beneficial for understanding the adverse effect of PAEs and phthalate monoesters.

Fluorination of PVC medical devices to prevent plasticizers migration

Medical devices (MD) are often made of plasticized polyvinylchloride (PVC). However, plasticizers may leach out into infused solutions and expose the patients to a toxic risk. The aim of the present work is to fluorinate plasticized PVC tubular MDs to create a barrier layer on their internal surface, and to study the impact of such a chemical treatment on the migration of the plasticizers. Following fluorination by pure molecular fluorine, the physico-chemical characterization of these modified MDs was carried out using various spectroscopic and microscopic techniques or tensile tests, evidencing the formation of covalent C-F bonds on the surface of the treated samples without modification of their mechanical and optical properties. The migration of plasticizers from fluorinated MDs was assessed using gas chromatography coupled with mass spectrometry and was found considerably decreased in comparison with the pristine MDs. After 24 h, the amount of tri-octyltrimellitate plasticizer (TOTM) detected in migrates from fluorinated MDs was even lower than the limit of quantification. Complementary cytotoxicity assays were performed according to the ISO EN 10993-5 standard, showing that the new fluorinated material does not cause a cytotoxic effect on L929 cells.

Lurgi-Thyssen dust catalytic thermal desorption remediation of di-(2-ethylhexyl) phthalate contaminated soils

Fe2O3-assisted pyrolysis has been demonstrated to be a cost-effective thermal desorption (TD) technology. Lurgi-Thyssen dust (LTD) is a type of steel slag waste that contains a large amount of Fe2O3. In this study, to reduce energy consumption, LTD was added to contaminated soil to evaluate the feasibility of enhancing the TD removal efficiency of di-(2-ethylhexyl) phthalate (DEHP). The DEHP removal rate increased by 22.39% after adding 2% LTD at 200 °C for 20 min. Because of the catalytic pyrolysis of LTD, DEHP was pyrolyzed to form three types of short-chain esters: mono-(2-ethylhexyl) phthalate (MEHP), di (2-methylbutyl) ester, and methyl 2-ethylhexyl phthalate. The pyrolysis products of DEHP were less toxic and did not affect soil reuse. When the DEHP removal rate was 87.10%, LTD addition decreased the temperature and residence time of TD and alleviated the effect of TD on the soil physicochemical properties. Additionally, the desorption of DEHP from soil fitted the pseudo-second-order kinetic model well. Thus, the addition of LTD to contaminated soil enhanced the efficiency of TD remediation. Moreover, this study could provide a practical and economical strategy for LTD reuse.

Treatment of DEHP-rich PVC waste in subcritical urine wastewater: Efficient dechlorination, denitrification, plasticizer decomposition, and preparation of high-purity phthalic acid crystals

It is difficult to dispose diethylhexyl phthalate-rich polyvinyl chloride (DEHP-rich PVC) waste due to the high level of chlorine and plasticizer. On the other hand, the denitrification of urine wastewater with high nitrogen content also faces great challenges. In this study, a synergistic treatment strategy was developed for the DEHP-rich PVC waste and urine wastewater by a subcritical water process. Subcritical urine wastewater (SUW) was used as a reaction medium in the synergistic treatment. PVC dechlorination, DEHP decomposition, and denitrification of urine wastewater were synchronously achieved in the one pot SUW. Under the optimal conditions (300 °C, 15 min, 1:5 g/mL), the PVC dechlorination ratio, urine wastewater denitrification ratio and DEHP decomposition ratio could reach 98.4%, 64.9%, and 99.2%, respectively. The decomposition of DEHP mainly included hydrolysis, nucleophilic substitution, and acylation. DEHP could be converted into phthalic acid crystal at 220 °C with a yield of 66.25% due to the efficient hydrolysis action of SUW. All the removed Cl was transferred from PVC matrix to aqueous phase. Hydroxyl nucleophilic substitution is the principal dechlorination path of PVC. The reactions between N-containing species and DEHP in SUW resulted in the high-efficiency denitrification of urine wastewater, and the N element was fixed in solid residue or transferred to oil phase as amides compounds. It is believed that the proposed SUW process is a promising technology for the synergistic treatment of DEHP-rich PVC waste and urine wastewater.

Biochemical pathways and associated microbial process of di-2-ethyl hexyl phthalate (DEHP) enhanced degradation by the immobilization technique in sequencing batch reactor

A bacterial strain ASLT-13 was successfully isolated from activated sludge and identified as Pseudomonas amygdali. Gas chromatograph-mass spectrometer (GC-MS) analysis indicated that strain ASLT-13 could completely mineralize di 2-ethyl hexyl phthalate (DEHP). DEHP was first metabolized from the longer side chain of the benzene ring into shorter branches (Phatlalic mono-esters) like Dibutyl phthalate (DBP) under the action of degrading genes. DBP was then converted into di-methyl phthalate (DMP), and then hydrolysed to phthalic acid (PA). PA was eventually converted to CO₂ and H₂O through the TCA cycle. The optimal conditions for immobilization were the sodium alginate (SA) concentration of 6%, CaCl₂ concentration of 5%, ratio of bacteria and SA of 1:1, crosslinking time of 6 h. Bacterial quantity and community structure in sequencing batch reactors (SBRs) was investigated by q-PCR and high-throughput sequencing. The results indicated that DEHP removal efficiency was significantly enhanced by immobilization. Arthrobacter, Acinetobacter, Bacillus and Rhodococcus were the predominant genera for DEHP degradation. This study suggested that the cell immobilization technology had a potential application in DEHP wastewater treatment.

Toxicokinetics of mono-(2-ethylhexyl) phthalate with low-dose exposure applying fluorescence tracing technique

Di(2-ethylhexyl) phthalate (DEHP) belongs to environmental endocrine disrupting chemicals (EEDCs) and can be rapidly hydrolyzed into the ultimate toxicant mono-2-ethylhexyl phthalate (MEHP). In this study, we used 5-aminofluorescein modified MEHP (MEHP-AF) as a fluorescence tracer to explore the toxicokinetics, including toxicokinetic parameters, absorption and transport across the intestinal mucosal barrier, distribution and pathological changes of organs. While the dose was as lower than 10 mg/kg by intragastric administration, the toxicokinetic parameters obtained by fluorescence microplate method were similar to those with the literatures by chromatography. MEHP-AF can be rapidly absorbed through the intestinal mucosal barrier in rats. In situ organ distribution in mice showed that MEHP-AF was mainly concentrated in the liver, kidney and testis. Our results suggested that the fluorescence tracing technique had the advantages with easy processing, less time-consuming, higher sensitivity for the quantitative determination, In addition, this technology also avoids the interference of exogenous or endogenous DEHP and MEHP in the experimental system. It also can be utilized to the visualization detection of MEHP in situ localization in the absorption organ and the toxic target organ. The results show that this may be a more feasible MEHP toxicological research method.

Development and validation of a liquid chromatography/tandem mass spectrometry method to quantify metabolites of phthalates, including di-2-ethylhexyl terephthalate (DEHTP) and bisphenol A, in human urine

RATIONALE

Several phthalates and bisphenol A are endocrine-disrupting chemicals (EDCs). Recently, their use has been partially restricted and less toxic compounds, such as di-2-ethylhexyl terephthalate (DEHTP), have been placed on the market. The aim of this work was to develop and validate a method for the simultaneous quantitation of bisphenol A and urinary metabolites of phthalates, including DEHTP.

METHODS

An isotopic dilution high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC/ESI-MS/MS) method for the determination of bisphenol A (BPA), monobenzyl phthalate (MBzP), mono-2-ethyl-5-carboxypentyl phthalate (MECPP), mono-2-ethyl-5-carboxypentyl terephthalate (MECPTP), mono-2-ethyl-5-hydroxyhexyl terephthalate (MEHHTP), monoethyl phthalate (MEP), and mono-n/i-butyl phthalates (MnBP/MiBP) in human urine was developed. A complete validation was carried out and the method was applied to 36 non-occupationally exposed adults.

RESULTS

Limits of quantitation ranged from 0.02 (MECPP) to 1 μg/L (MnBP and MiBP). Relative standard deviations below 10% indicated a suitable precision; accuracy, evaluated using a standard reference material, ranged from 74.3% to 117.5%; isotopically labelled internal standards were suitable for correcting the matrix effect. The accuracy was confirmed by the successful participation in an external verification exercise. However, for terephthalates, the validation was incomplete due to the lack of reference materials and external verification. Levels of the investigated chemicals in subjects were in line with those previously reported.

CONCLUSIONS

An LC/MS/MS assay for the simultaneous measurement of BPA and phthalate metabolites in human urine was developed and validated; it is useful to investigate exposure in epidemiological studies involving the general population.

Placental Trophoblast-Inspired Lipid Bilayers for Cell-Free Investigation of Molecular Interactions

The placenta plays a key role in regulating the maternal-fetal transport but it is a difficult organ to study due to a lack of existing in vitro models. Lipid bilayers inspired by the placenta can provide a facile new in vitro tool with promise for screening molecular transport across this important organ. Here we developed lipid bilayers that mimic the composition of human placental trophoblast cells at different times during the course of pregnancy. Mass spectrometry identified five major lipid classes (phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, and sphingomyelin) present at varying concentrations in trophoblasts representative of the first and third trimesters and full-term placenta. We successfully developed supported and suspended lipid bilayers mimicking these trophoblast lipid compositions and then demonstrated the utility of these synthetic placenta models for investigating molecular interactions. Specifically, we investigated the interactions with di(2-ethylhexyl) phthalate (DEHP), a common plasticizer and environmental toxicant, and amphotericin B, a common yet toxic, antifungal therapeutic. Overall, we observed that DEHP adsorbs and potentially embeds itself within all placental lipid bilayers, with varying levels of interaction. For both amphotericin B and a liposomal formulation of amphotericin B, AmBisome, we noted lower levels of permeation in transport studies with bilayers and trophoblast cells compared with DEHP, likely driven by differences in size. AmBisome interacted less with both the supported and suspended placental lipid bilayers in comparison to amphotericin B, suggesting that drug delivery carriers can vary the impact of a pharmaceutical agent on these lipid structures. We found that the apparent permeability observed in suspended bilayers was approximately an order of magnitude less than those observed for trophoblast monolayers, which is typical of lipid bilayers. Ultimately, these placenta mimetic lipid bilayers can serve as a platform for the rapid initial screening of molecular interactions with the maternal-fetal interface to better inform future testing.

Electrochemical Quantitative Assessment of Labetalol Hydrochloride in Pure Form and Combined Pharmaceutical Formulations

This work describes how to utilize the electrochemical technique to determine labetalol hydrochloride (Lab) in pure form and combined pharmaceutical formulation for quality control purposes. Four membrane sensors were developed using two plasticizers, dioctyl phthalate with 2-hydroxypropyl-?-cyclodextrin and ammonium reineckate (RNC) for sensors 1a and 2a, and tributyl phthalate with 2-hydroxypropyl-?-cyclodextrin and ammonium reineckate for sensors 1b and 2b as ionophores in polyvinyl chloride (PVC) matrix. Fast response and stable Nernstian slopes of 59.60, 57.58, 53.00 and 55.00 mV/decade for sensors 1a, 2a, 1b, and 2b, respectively, were obtained by developed sensors within a concentration range 10-4 M-10-2 M over pH range 2.00-5.10. Developed sensors showed good selectivity for Lab in pure form, in the presence of co-administered drugs, many of interfering ions, and excipients present in pharmaceutical formulation. No remarkable difference was detected upon the statistical comparison between the results of proposed sensors and the official method.

DEHP degradation and dechlorination of polyvinyl chloride waste in subcritical water with alkali and ethanol: A comparative study

In this study, subcritical water-NaOH (CW-NaOH) and subcritical water-C₂H₅OH (CW-C₂H₅OH) processes were developed for diethylhexyl phthalate (DEHP) degradation and dechlorination of polyvinyl chloride (PVC) waste. The introduction of NaOH or C₂H₅OH in subcritical water had a noticeable influence on the mechanism of DEHP degradation and dechlorination. For both CW-NaOH and CW-C₂H₅OH treatments, the increase in temperature could increase dechlorination efficiency (DE) of PVC. The DE of CW-NaOH is much higher than that of CW-C₂H₅OH under the same conditions. The DE of CW-NaOH could exceed 95% at 300 °C. Hydroxyl nucleophilic substitution was the main dechlorination mechanism in CW-NaOH, while nucleophilic substitution and direct dehydrochlorination were equally important in CW-C₂H₅OH. In CW-NaOH treatment, 2-ethyl-1-hexanol, benzaldehyde, and toluene were obtained by hydrolysis and reduction reactions of DEHP. Acetophenone was produced by the further cyclization, dehydrogenation and rearrangement reactions of 2-ethyl-1-hexanol. Transesterification was the main degradation pathway of DEHP in CW-C₂H₅OH at 300 °C. The cyclization and dehydration of 2-ethyl-1-hexanol resulted in producing a high level of ethyl-cyclohexane and 1-ethyl-cyclohexene in CW-C₂H₅OH at 350 °C. Furthermore, high concentration of ethyl palmitate and ethyl stearate could be prepared in CW-C₂H₅OH system by the strong reactivity of C₂H₅OH with the lubricants in PVC.

Photolysis of bis(2-ethylhexyl) phthalate in aqueous solutions at the presence of natural water photoreactive constituents under simulated sunlight irradiation

The photolysis of bis(2-ethylhexyl) phthalate (DEHP) under simulated sunlight in the presence of the natural water photoreactive constituents was investigated. The presence of nitrate or ferric ions facilitated the photodegradation of DEHP via oxidation by generation of •OH. The fulvic acids (FAs), at low concentrations, promoted the photolysis of DEHP via energy transfer from the photoreaction-generated ³FA*. However, the DEHP photolysis was inhibited with high concentrations of FAs since the excess FAs at the surface of solution could act as light screening agents to keep FAs in bulk solution from the light irradiation, further reducing the ³FA* generation. When low concentrations of FAs and chloride ions coexist, the reactive chloride species Cl• and Cl₂•^- could generate via energy transfer from ³FA* to chloride ions and react with DEHP to enhance its degradation. Furthermore, the direct and •OH-initiated DEHP photodegraded intermediates and end products were identified by HPLC-MS² and its corresponding photolysis pathways were proposed.

Populus alba dioctyl phthalate uptake from contaminated water

Phthalates are micro-pollutants of great concern due to their negative effects on ecosystem functioning and human health. Thanks to its capability in uptake and accumulation of organic pollutants, Populus alba L. "Villafranca" clone could be a good candidate for reducing the impacts derived by the persistence of such compounds in the environment. We investigated plant response and uptake of dioctyl phthalate (DOP) by poplar, grown in hydroponics condition, for 21 days with 0, 40, and 400 μg L^-1 of d₄-DOP. Treated plants, after 21 days of 400 μg L^-1 d₄-DOP, showed an increase in root dry biomass (+ 29%) at the expense of aerial parts (- 8%) compared with control. The root development could be sustained by the increase of Mg uptake by poplar. LC-MS/MS analysis demonstrated the uptake and accumulation in roots of d₄-DOP starting from day one (3.5 ± 3.29 and 7.1 ± 3.28 in 40 and 400 μg L^-1 d₄-DOP respectively), despite volatilization of d₄-DOP was observed from nutritive solution. The chemical interaction between d₄-DOP and Zn occurred in roots of plants treated with the high d₄-DOP concentration, without limiting the Zn concentration in leaves. Results confirm the high tolerance of "Villafranca" clone to xenobiotic and suggest the poplar capability in d₄-DOP uptake and accumulation at root level.

Effect of biochars on the bioavailability of cadmium and di-(2-ethylhexyl) phthalate to Brassica chinensis L. in contaminated soils

Soil co-contamination of potentially toxic elements (PTEs) and phthalate esters has become prominent due to its potential adverse effect on human food supply. There is limited information on using wood- and animal-derived biochars for the remediation of co-contaminated soils. Therefore, a pot experiment was conducted using Brassica chinensis L. as a bio-indicator plant to investigate the effect of P. orientalis biochar and pig biochar application on the bioavailability of cadmium (Cd) and di-(2-ethylhexyl) phthalate (DEHP) and on plant physiological parameters (malondialdehyde, proline and soluble sugars). Biochar materials were applied to two soils containing low (LOC) and high (HOC) organic carbon content at rates of 0, 0.5, 1, 2, and 4%. To better understand the influence of biochar, physicochemical properties and X-ray diffraction (XRD), energy dispersive X-ray spectrometry (EDS), Fourier transform-infrared spectrometry (FTIR), scanning electron microscopy (SEM) were characterized. Biochar application increased soil pH, organic carbon content, and available phosphorus content. Increasing biochar application rates decreased DTPA-extractable Cd and extractable DEHP concentrations in both soils. Biochar application reduced the plant uptake of both Cd and DEHP from co-contaminated soils; the maximum reduction of Cd (92.7%) and DEHP (52.0%) was observed in 2% pig biochar-treated LOC soil. The responses of plant physiological parameters to increased biochar applications indicated that less Cd and DEHP were taken up by plants. Pig biochar was more effective (P < 0.05) at reducing the bioavailability of Cd and DEHP in both soils than P. orientalis biochar; therefore, pig biochar had greater potential for improving the quality of the crop. However, the highest application rate (4%) of pig biochar restricted plant seed germination. Key factors influencing the bioavailability of Cd and DEHP in soils were soil organic carbon content, biochar properties (such as surface alkalinity, available phosphorus content and ash content) and biochar application rates.

Biodegradation of Structurally Diverse Phthalate Esters by a Newly Identified Esterase with Catalytic Activity toward Di(2-ethylhexyl) Phthalate

Herein, we report a double enzyme system to degrade 12 phthalate esters (PAEs), particularly bulky PAEs, such as the widely used bis(2-ethylhexyl) phthalate (DEHP), in a one-pot cascade process. A PAE-degrading bacterium, Gordonia sp. strain 5F, was isolated from soil polluted with plastic waste. From this strain, a novel esterase (GoEst15) and a mono(2-ethylhexyl) phthalate hydrolase (GoEstM1) were identified by homology-based cloning. GoEst15 showed broad substrate specificity, hydrolyzing DEHP and 10 other PAEs to monoalkyl phthalates, which were further degraded by GoEstM1 to phthalic acid. GoEst15 and GoEstM1 were heterologously coexpressed in Escherichia coli BL21 (DE3), which could then completely degrade 12 PAEs (5 mM), within 1 and 24 h for small and bulky substrates, respectively. To our knowledge, GoEst15 is the first DEHP hydrolase with a known protein sequence, which will enable protein engineering to enhance its catalytic performance in the future.

Fate of di (2-ethylhexyl) phthalate and its impact on soil bacterial community under aerobic and anaerobic conditions

In this study, we examined the influence of oxygen on the degradation of di (2-ethylhexyl) phthalate (DEHP), the accumulation of its monoester metabolite mono (2-ethylhexyl) phthalate (MEHP) and their impact on soil bacterial communities. Soil microcosms artificially contaminated with DEHP (0, 100 and 1000 mg kg^-1) were incubated under aerobic and anaerobic flooded conditions, and sacrificed after 0, 21 and 42 days. The results indicated that DEHP degradation proceeded at similar rates in aerobic and anaerobic flooded soils, but accumulation of metabolite MEHP was more likely to occur in anaerobic soils. Moreover, MEHP generated from DEHP degradation seemed to be readily released into the water phase, which may arouse health concerns. Illumina Miseq sequencing showed that MEHP had a greater impact on soil bacterial community than DEHP at the same dosage, and a wide range of bacterial phylotypes were inhibited by MEHP under anaerobic conditions. High DEHP contamination (1000 mg kg^-1) significantly reduced bacterial diversity and altered bacterial community structure under anaerobic conditions, but not under aerobic conditions. Firmicutes was constantly inhibited by DEHP under both aerobic (Bacillus) and anaerobic (unclassified Clostridiales Family_XVIII) conditions. On the other hand, bacterial phylotypes belonging to Actinobacteria, β-Proteobacteria and Gemmatimonadaceae were constantly enriched by DEHP in anaerobic soils, however no such a clear pattern existed in aerobic soils. This work greatly expanded our understanding of the fate of DEHP and its modifying effect on bacterial communities under different environmental conditions.

Soil ecotoxicity study of DEHP with respect to multiple soil species

Di (2-ethylhexyl) phthalate or DEHP is classified as an endocrine-disrupting chemical. It is used as a plasticizer and pesticide additive. Moreover, it has a half-life of about 150-300 days. Thus, it is present in the soil environment and soil risk assessments for DEHP are needed. However, a number of studies have focused on the effects of DEHP in a single soil species. In this study, we conducted acute and chronic toxicity testing for DEHP using varied soil species, including plants, earthworms, soil algae, Collembola, and soil nematodes. In the plant toxicity test, no effect was observed at very high concentration except at some endpoints, and no effect was observed in the earthworm toxicity test. However, there were adverse effects on soil algae, Collembola, and nematodes. Notably, in the Collembola assays, the survival of adults decreased significantly at very high concentrations, whereas reproduction was hindered at low concentrations. Similar inhibition of reproduction was noted in the soil nematode assay. This suggests that DEHP has a greater influence on fertility than survival in the adult test species. However, besides hindered reproduction, no effect was observed on soil species at environmentally relevant concentrations.

Variations in microbial community and di-(2-ethylhexyl) phthalate (DEHP) dissipation in different rhizospheric compartments between low- and high-DEHP accumulating cultivars of rice (Oryza sativa L.)

Di-(2-ethylhexyl) phthalate (DEHP) is a typical endocrine disrupting chemical with relatively high concentrations in agricultural soils of China. Here, a rhizobox experiment was conducted to investigate the variations in microbial community and DEHP dissipation among different soil rhizospheric compartments between low (Fengyousimiao) and high (Peizataifeng) DEHP-accumulating cultivars of rice (Oryza sativa L.) grown in DEHP spiked soil (0, 20, 100 mg/kg). The dissipation rates of DEHP in rhizospheric soils of Peizataifeng were generally significantly higher than those of Fengyousimiao, with the highest removal rate in 0-2 mm rhizosphere. The results of Illumina-HiSeq high-throughput sequencing revealed that both bacterial and fungal diversity and community structure were significantly different in rhizospheric soils of the two cultivars. DEHP dissipation rates in 0-2 mm rhizosphere of Peizataifeng were positively correlated with bacterial and fungal diversity. The relative abundance of DEHP-degrading bacterial genera Acinetobacter, Pseudomonas and Bacillus of Peizataifeng was generally higher than those in the same rhizospheric compartment of Fengyousimiao in DEHP treatments, resulting in different rhizospheric DEHP dissipation. Cultivation of Peizataifeng in agricultural soil is promising to facilitate DEHP dissipation and ensure safety of agricultural products.

Disruption of ergosterol and tryptophan biosynthesis, as well as cell wall integrity pathway and the intracellular pH homeostasis, lead to mono-(2-ethylhexyl)-phthalate toxicity in budding yeast

Endocrine disrupting chemicals (EDCs) are substances in the environment, food, and consumer products that interfere with hormone homeostasis, metabolism or reproduction in humans and animals. One such EDC, the plasticizer di-(2-ethylhexyl)-phthalate (DEHP), exerts its function through its principal bioactive metabolite, mono-(2-ethylhexyl)-phthalate (MEHP). To fully understand the effects of MEHP on cellular processes and metabolism as well as to assess the impact of genetic alteration on the susceptibility to MEHP-induced toxicity, we screened MEHP-sensitive mutations on a genome-scale in the eukaryotic model organism Saccharomyces cerevisiae. We identified a total of 96 chemical-genetic interactions between MEHP and gene mutations in this study. In response to MEHP treatment, most of these gene mutants accumulated higher intracellular MEHP content, which correlated with their MEHP sensitivity. Twenty-seven of these genes are involved in the metabolism, twenty-two of them play roles in protein sorting, and ten of them regulate ion homeostasis. Functional categorization of these genes indicated that the biosynthetic pathways of both ergosterol and tryptophan, as well as cell wall integrity and the intracellular pH homeostasis, were involved in the protective response of yeast cells to the MEHP toxicity. Our study demonstrated that a collection of yeast gene deletion mutants is useful for a functional toxicogenomic analysis of EDCs, which could provide important clues to the effects of EDCs on higher eukaryotic organisms.

Characterization of a di-n-butyl phthalate-degrading bacterial consortium and its application in contaminated soil

Dibutyl phthalate (DBP), as a plasticizer, is widely used in China, and it is easily released into diverse environments. In this study, we have obtained a stable bacterial consortium (B1) enriched from municipal sewage treatment plant activated sludge. The obtained bacterial consortium B1 was capable of degrading DBP and was mainly composed of Pandoraea sp. and Microbacterium sp. From the initial concentrations of 35-500 mg L^-1, DBP was efficiently degraded by the consortium, with the degradation rates above 92% within 3 days. The optimal temperature for DBP degradation was 30 °C and consortium B1 could adapt to a wide range of pH (5.5-8.5). The analysis of Illumina sequencing further showed that the relative abundance of Pandoraea was increased at the beginning of the degradation, while Microbacterium was decreased. In the later stage of the degradation, the change of the relative abundance of Pandoraea and Microbacterium was opposite. Apart from DBP, consortium B1 could also utilize dimethyl phthalate (DMP), di-2-ethylhexyl phthalate (DEHP), and phthalic acid (PA) as the sole carbon. Moreover, adding B1 to DBP-contaminated soil could greatly improve the removal rate of DBP, suggesting that B1 has a great potential for the bioremediation of DBP-contaminated environments.

Phthalate exposure and high blood pressure in adults: a cross-sectional study in China

Widespread phthalate exposure has been recently documented and is hypothesized to increase blood pressure (BP) in humans. However, current studies have provided inconclusive evidence for an association between phthalate exposure and BP. Human epidemiologic studies on the topic remain lacking. Therefore, this study aims to examine the association between serum phthalate concentrations and BP in a Chinese population. We measured several parameters of BP (systolic BP, diastolic BP, total cholesterol, and triglyceride) and the concentrations of 16 phthalates (dimethyl phthalate (DMP), diethyl phthalate, diisobutyl phthalate, dibutyl phthalate (DBP), bis (2-methoxyethyl) phthalate, bis (4-methyl-2-pentyl) phthalate, bis (2-ethoxyethyl) phthalate, diamyl phthalate, dihexyl phthalate, benzyl butyl phthalate, bis (2-nbutoxyethyl) phthalate (DBEP), dicyclohexyl phthalate, bis (2-ethyl hexyl) phthalate (DEHP), diisononyl phthalate, diphenyl phthalate, and di-n-octyl phthalate) in the serum of 474 adults recruited from a primary health care clinic. The relationship between serum phthalate concentrations and BP parameters was assessed with multivariate linear regressions. DBP was the most ubiquitous and dominant contaminant in the study population. The systolic BP of subjects in the median-exposure DEHP group significantly increased by 2.96 mmHg (p < 0.05) relative to that of subjects in the low-exposure group. Significant positive dose-related associations of DMP and DBEP with the levels of total cholesterol in serum (p for trend < 0.05) were also found. These associations persisted even when considering exposure to multiple phthalates. Our results suggested that phthalate exposure might increase BP in adults. However, our findings warrant further studies in a larger and more general population.

Phthalate esters distribution in coastal mariculture of Hong Kong, China

The aim of the study is to evaluate the impact of mariculture on phthalate esters speciation and distribution in sediments and cultured fish in the Hong Kong regions and near mainland China. Concentrations of ∑phthalate esters in mariculture surface sediments (0 to 5 cm) ranged from 0.20 to 54.3 mg/kg dw (mean 10.3 mg/kg dw), with the highest recorded at M2 (20.4 mg/kg dw). Concentrations of phthalate esters were not significantly (p > 0.05) enriched in surface and sediment cores at mariculture sites relative to the reference sediments, 1 to 2 km away in areas without mariculture activities. Among different congeners, only butyl benzyl phthalate (BBP) concentrations demonstrated a significant correlation (R² = 0.40, p < 0.05) with TOC values of sediments. The median concentrations of di-2-ethylhexyl phthalate (DEHP) and di-n-butyl phthalate (DBP) in the sediments were 1.57 and 6.96 times higher than the environmental risk levels (ERL), which may pose environmental risks. Results of health risk assessments revealed that the cultured fish (snubnose pompano, orange-spotted grouper, and red snapper) were safe for consumption, in terms of phthalate esters. This is the first study to assess the differences of phthalate esters contamination between mariculture and natural coastal sediments.

Fate of four phthalate plasticizers under various wastewater treatment processes

The fate of four phthalate plasticizers during wastewater treatment processes at six different wastewater treatment plants (WWTPs) was investigated. Concentrations of benzyl butyl phthalate (BBP), di(2-ethylhexyl) phthalate (DEHP), diisononyl phthalate (DiNP), and diisodecyl phthalate (DiDP) were determined prior to either aerobic or anaerobic (conventional and advanced) treatment, after treatment, and in final, dewatered solids. Despite their elevated use worldwide, the fate of DiNP and DiDP during wastewater treatment have not been well characterized. DEHP was readily degraded during aerobic treatments while anaerobic digestion resulted in either no significant change in concentrations or an increase in concentration, in the case of more advanced anaerobic processes (thermal hydrolysis pretreatment and a two-phase acid/gas process). Impacts of the various treatment systems on DiNP, DiDP, and BBP concentrations were more varied - anaerobic digestion led to significant decreases, increases, or no significant change for these compounds, depending on the treatment facility, while aerobic treatment was generally effective at degrading the compounds. Additionally, thermal hydrolysis pretreatment of sludge prior to anaerobic digestion resulted in increases in DiNP, DiDP, and BBP concentrations. The predicted environmental concentrations for all four compounds in soils after a single biosolids application were calculated and the risk quotients for DEHP in soils were determined. The estimated toxicity risk for DEHP in soils treated with a single application of sludge from any of the six studied WWTPs is lower than the level of concern for acute and chronic risk, as defined by the US EPA.

Is there any association between phthalate exposure and precocious puberty in girls?

Considerable increase in the prevalence of precocious puberty (PP) during the last decade has raised a lot of concerns. Some environmental endocrine disruptor chemicals (EDCs), such as phthalate esters, have intrinsic estrogen activity or increase endogenous sex hormone levels leading to PP. This study was conducted to investigate the association between exposure to phthalate esters and PP in a sample of girls. Plasma levels of seven phthalate ester metabolites were measured in 87 girls with PP and 63 age- and sex-matched controls by dispersive liquid-liquid microextraction and GC/MS analysis. History of exposure to main sources of phthalates was obtained by a checklist. Diethyl hexyl phthalate (DEHP) metabolite levels were significantly higher in those with PP than that in controls (p < 0.05), but this difference was not significant for other phthalate metabolites. 30.1% girls with PP and 12.2% of controls had played for more than 2 h/day with plastic toys in their childhood. 65.1% girls with PP and 32.8% of controls have regularly used some cosmetic products. Consumption of bottled water and beverages by those with PP was about twofold higher than that in the control group. A positive correlation was found between bottled ware consumption and plasma concentrations of four phthalate metabolites. The frequency of seafood consumption was not significantly different between the groups studied. Our findings confirm positive association between phthalate exposure and incidence of PP in girls. Control and reduction of children exposure to phthalate esters should be considered as a health priority.

Biphasic modulation of neuro- and interrenal steroidogenesis in juvenile African sharptooth catfish (Clarias gariepinus) exposed to waterborne di-(2-ethylhexyl) phthalate

Receptor (i.e. genomic) and non-receptor (or non-genomic) effects of endocrine toxicology have received limited or almost non-existent attention for tropical species and regions. In the present study, we have evaluated the effects of di-(2-ethylhexyl) phthalate (DEHP) on neuro- and interrenal steroidogenesis of the African catfish (Clarias gariepinus) using molecular, immunochemical and physiological approaches. Juvenile fish (mean weight and length: 5.6±0.6g and 8.2±1.2cm, respectively), were randomly distributed into ten 120L rectangular glass tanks containing 60L of dechlorinated tap water, at 50 fish per exposure group. The fish were exposed to environmentally relevant concentrations of DEHP, consisting of 0 (ethanol solvent control), 10, 100, 200, and 400μg DEHP/L water and performed in two replicates. Brain, liver and head kidney samples were collected at day 3, 7 and 14 after exposure, and analysed for star, p450scc, cyp19a1, cyp17, cyp11β-, 3β-, 17β- and 20β-hsd, and 17β-ohase mRNA expression using real-time PCR. The StAR, P450scc and CYP19 proteins were measured using immunoblotting method, while estradiol-17β (E2) and testosterone (T) were measured in liver homogenate using enzyme immunoassay (EIA). Our data showed a consistent and unique pattern of biphasic effect on star and steroidogenic enzyme genes with increases at low concentration (10μg/L) and thereafter, a concentration-dependent decrease in both the brain and head kidney, that paralleled the expression of StAR, P450scc and CYP19 proteins. Cellular E2 and T levels showed an apparent DEHP concentration-dependent increase at day 14 of exposure. The observed consistency in the current findings and in view of previous reports on contaminants-induced alterations in neuro- and interrenal steroidogenesis, the broader toxicological and endocrine disruptor implication of our data indicate potentials for overt reproductive, metabolic, physiological and general health consequences for the exposed organisms.

Biodegradation of phthalic acid esters (PAEs) and in silico structural characterization of mono-2-ethylhexyl phthalate (MEHP) hydrolase on the basis of close structural homolog

Three bacterial strains capable of degrading phthalates namely Pseudomonas sp. PKDM2, Pseudomonas sp. PKDE1 and Pseudomonas sp. PKDE2 were isolated and characterized for their degradative potential. These strains efficiently degraded 77.4%-84.4% of DMP, 75.0%-75.7% of DEP and 71.7%-74.7% of DEHP, initial amount of each phthalate is 500mgL^-1 of each phthalate, after 44h of incubation. GC-MS results reveal the tentative DEHP degradation pathway, where hydrolases mediate the breakdown of DEHP to phthalic acid (PA) via an intermediate MEHP. MEHP hydrolase is a serine hydrolase which is involved in the reduction of the MEHP to PA. The predicted 3D model of MEHP hydrolase from Pseudomonas mosselii was docked with phthalate monoesters (PMEs) such as MEHP, mono-n-hexyl phthalate (MHP), mono-n-butyl phthalate (MBP) and mono-n-ethyl phthalate (MEP), respectively. Docking results show the distance between the carbonyl carbon of respective phthalate monoester and the hydroxyl group of catalytic serine lies in the range of 2.9 to 3.3Å, which is similar to the ES complex of other serine hydrolases. This structural study highlights the interaction and the role of catalytic residues of MEHP hydrolase involved in the biodegradation of PMEs to phthalate.

Toxic effects of polyethylene terephthalate microparticles and Di(2-ethylhexyl)phthalate on the calanoid copepod, Parvocalanus crassirostris

Large amounts of plastic end up in the oceans every year where they fragment into microplastics over time. During this process, microplastics and their associated plasticizers become available for ingestion by different organisms. This study assessed the effects of microplastics (Polyethylene terephthalate; PET) and one plasticizer (Di(2-ethylhexyl)phthalate; DEHP) on mortality, productivity, population sizes and gene expression of the calanoid copepod Parvocalanus crassirostris. Copepods were exposed to DEHP for 48h to assess toxicity. Adults were very healthy following chemical exposure (up to 5120µg L^-1), whereas nauplii were severely affected at very low concentrations (48h LC₅₀value of 1.04 ng L^-1). Adults exposed to sub-lethal concentrations of DEHP (0.1-0.3µg L^-1) or microplastics (10,000-80,000 particles mL^-1) exhibited substantial reductions in egg production. Populations were exposed to either microplastics or DEHP for 6 days with 18 days of recovery or for 24 days. Populations exposed to microplastics for 24 days significantly depleted in population size (60±4.1%, p<0.001) relative to controls, whilst populations exposed for only 6 days (with 18 days of recovery) experienced less severe depletions (75±6.0% of control, p<0.05). Populations exposed to DEHP, however, exhibited no recovery and both treatments (6 and 24 days) yielded the same average population size at the termination of the experiment (59±4.9% and 59±3.4% compared to control; p<0.001). These results suggest that DEHP may induce reproductive disorders that can be inherited by subsequent generations. Histone 3 (H3) was significantly (p<0.05) upregulated in both plastic and DEHP treatments after 6 days of exposure, but not after 18 days of recovery. Hsp70-like expression showed to be unresponsive to either DEHP or microplastic exposure. Clearly, microplastics and plasticizers pose a serious threat to zooplankton and potentially to higher trophic levels.

A systematic review on the adverse health effects of di-2-ethylhexyl phthalate

Di (ethylhexyl) phthalate (DEHP) is a global environmental pollutant. This study aims to systematically review the literature on health effects of exposure to DEHP including effects on reproductive health, carcinogenesis, pregnancy outcome, and respiratory system. The literature search was done through Scopus, ISI Web of Science, Google Scholar, PubMed, Medline, and the reference lists of previous review articles to identify relevant articles published to June 2016 in each subject area. The inclusion criteria were as follows: original research, cross-sectional studies, case-control studies, cohort studies, interventional studies, and review articles. Both human and animal studies were included. The search was limited to English language papers. Conference papers, editorials, and letters were not included. The systematic review was conducted and reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Overall, 152 of the 407 papers met the inclusion criteria. We provided an up-to-date comprehensive and critical assessment of both human and animal studies undertaken to explore the effects of DEHP. It revealed that in experimental studies, exposure to DEHP mainly targeted the reproductive, neurodevelopment, and respiratory systems. Human studies reported that exposure to this contaminant had carcinogenic effects and influenced neurodevelopment in early life. This systematic review underscored the adverse health effects of DEHP for pregnant women and the pediatric age group. It summarizes different response of humans and experimental animals to DEHP exposure, and some suggested underlying mechanisms.

Ionophore-based potentiometric PVC membrane sensors for determination of phenobarbitone in pharmaceutical formulations

The fabrication and development of two polyvinyl chloride (PVC) membrane sensors for assaying phenobarbitone sodium are described. Sensors 1 and 2 were fabricated utilizing β- or γ-cyclodextrin as ionophore in the presence of tridodecylmethylammonium chloride as a membrane additive, and PVC and dioctyl phthalate as plasticizer. The analytical parameters of both sensors were evaluated according to the IUPAC guidelines. The proposed sensors showed rapid, stable anionic response (-59.1 and -62.0 mV per decade) over a relatively wide phenobarbitone concentration range (5.0 × 10-6-1 × 10-2 and 8 × 10-6-1 × 10-2 mol L-1) in the pH range of 9-11. The limit of detection was 3.5 × 10-6 and 7.0 × 10-6 mol L-1 for sensors 1 and 2, respectively. The fabricated sensors showed high selectivity for phenobarbitone over the investigated foreign species. An average recovery of 2.54 μg mL-1 phenobarbitone sodium was 97.4 and 101.1 %, while the mean relative standard deviation was 3.0 and 2.1 %, for sensors 1 and 2, respectively. The results acquired for determination of phenobarbitone in its dosage forms utilizing the proposed sensors are in good agreement with those obtained by the British Pharmacopoeial method.

Phthalate monoesters as markers of phthalate contamination in wild marine organisms

The level of phthalate esters (PAEs) alone is not considered to be a sufficient indicator of PAE pollution due to the quick metabolism of PAEs in the biota. The primary metabolites of PAEs, monoalkyl phthalate esters (MPEs), may also be an important indicator. However, PAE metabolism has scarcely been documented in wild marine organisms. We analysed five PAEs [dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), di(2-ethylhexyl) phthalate (DEHP), and di-n-octyl phthalate (DNOP)] and their corresponding MPEs [mono-methyl phthalate (MMP), mono-ethyl phthalate (MEP), mono-n-butyl phthalate (MBP), mono-2-ethylhexyl phthalate (MEHP), and mono-n-octyl phthalate (MNOP)] in 95 wild aquatic marine samples (including fish, prawns and molluscs) collected from the Yangtze River Delta area of the East China Sea. The species-dependent distribution of these compounds was associated with the food habits, living patterns and trophic levels of the biota. Slightly higher levels of hydrophobic PAEs (DBP and DEHP, logK_OW 4.27 and 7.33, respectively) were observed in fish species consuming benthic organisms or in demersal fish species, suggesting the importance of benthic organisms and sediment. Trophic dilution of both PAEs and MPEs implies further metabolic transformation at higher trophic levels. MPE tissue distributions in fish demonstrate that the highest concentrations were always observed in bile. Metabolism via the kidney and gill is a probable main way for the relatively less hydrophobic MPEs (logK_OW = <4.73, from MMP to MEHP), whereas metabolism via the liver is likely the main way for the most hydrophobic MNOP (logK_OW 5.22). Generally, higher detection frequencies of MPEs were observed than those of parent PAEs. Significant liner correlations were observed between the levels of short-branched (carbon atom per chain = <4) MPEs and the sum of PAEs and MPEs (n = 95, p < 0.01), demonstrating that short-branched MPEs can be used as biomarkers of exposure to quantitatively reflect parent PAE contamination in wild marine organisms.

Evaluation of toxicity and estrogenicity of the landfill-concentrated leachate during advanced oxidation treatment: chemical analyses and bioanalytical tools

Landfill-concentrated leachate from membrane separation processes is a potential pollution source for the surroundings. In this study, the toxicity and estrogenicity potentials of concentrated leachate prior to and during UV-Fenton and Fenton treatments were assessed by a combination of chemical (di (2-ethylhexyl) phthalate and dibutyl phthalate were chosen as targets) and biological (Daphnia magna, Chlorella vulgaris, and E-screen assay) analyses. Removal efficiencies of measured di (2-ethylhexyl) phthalate and dibutyl phthalate were more than 97 % after treatment with the two methods. Biological tests showed acute toxicity effects on D. magna tests in untreated concentrated leachate samples, whereas acute toxicity on C. vulgaris tests was not observed. Both treatment methods were found to be efficient in reducing acute toxicity effects on D. magna tests. The E-screen test showed concentrated leachate had significant estrogenicity, UV-Fenton and Fenton treatment, especially the former, were effective methods for reducing estrogenicity of concentrated leachate. The EEQchem (estradiol equivalent concentration) of all samples could only explain 0.218-5.31 % range of the EEQbio. These results showed that UV-Fenton reagent could be considered as a suitable method for treatment of concentrated leachate, and the importance of the application of an integrated (biological + chemical) analytical approach for a comprehensive evaluation of treatment suitability.

Positive association between concentration of phthalate metabolites in urine and microparticles in adolescents and young adults

Di-(2-ethylhexyl) phthalate (DEHP) has been used worldwide in various products for many years. In vitro studies have shown that exposure to DEHP and its metabolite mono(2-ethylhexyl) phthalate (MEHP) induces endothelial cell apoptosis. Moreover, exposure to DEHP had been linked to cardiovascular risk factors and cardiovascular diseases in epidemiological studies. Circulating microparticles have been known to be indicators of vascular injury. However, whether DEHP or its metabolites are independently associated with microparticles in humans remains unknown. From 2006 to 2008, we recruited 793 subjects (12-30years) from a population-based sample to participate in this cardiovascular disease prevention examination. Each participant was subjected to interviews and biological sample collection to determine the relationship between concentrations of DEHP metabolites MEHP, mono(ethyl-5-hydroxyhexyl) phthalate, and mono(2-ethly-5-oxoheyl) phthalate in urine and concentrations of endothelial microparticles (CD62E and CD31+/CD42a-), platelet microparticles (CD62P and CD31+/CD42a+), and CD14 in serum. Multiple linear regression analysis revealed that an ln-unit increase in MEHP concentration in urine was positively associated with an increase in serum microparticle counts/μL of 0.132 (±0.016) in CD31+/CD42a- (endothelial apoptosis marker), 0.117 (±0.023) in CD31+/CD42a+ (platelet apoptosis marker), and 0.026 (±0.007) in CD14 (monocyte, macrophage, and neutrophil activation marker). There was no association between DEHP metabolite concentration and CD62E or CD62P. In conclusion, a higher MEHP concentration in urine was associated with an increase in endothelial and platelet microparticles in this cohort of adolescents and young adults. Further studies are warranted to clarify the causal relationship between exposure to DEHP and atherosclerosis.

Comparative study on the migration of di-2-ethylhexyl phthalate (DEHP) and tri-2-ethylhexyl trimellitate (TOTM) into blood from PVC tubing material of a heart-lung machine

Medical devices like blood tubing often consist of PVC material that requires the addition of plasticizers. These plasticizers may migrate into the blood leading to an exposure of the patients. In this study the migration behavior of three different blood tubing sets (PVC material with two different plasticizers and silicone as control material) applied on a heart-lung machine standardly used for cardiopulmonary bypass (CPB) in children was studied. We analyzed the total plasticizer migration by analysis of both, the parent compounds as well as their primary degradation products in blood. Additionally, the total mass loss of the tubing over perfusion time was examined. The PVC tubing plasticized with DEHP (di-2-ethylhexyl phthalate) was found to have the highest mass loss over time and showed a high plasticizer migration rate. In comparison, the migration of TOTM (tri-2-ethylhexyl trimellitate) and its primary degradation products was found to be distinctly lower (by a factor of approx. 350). Moreover, it was observed that the storage time of the tubing affects the plasticizer migration rates. In conclusion, the DEHP substitute TOTM promises to be an effective alternative plasticizer for PVC medical devices particularly regarding the decreased migration rate during medical procedures.

[Determination of Plasticizer DEHP Released from Medical Injection Equipment]

To established an effective GC-MS /MS method for the contents determination of the residual DEHP in injection equipment, and investigate the effect of the pretreatment on the measurement. To simulate the clinical conditions of use, under the condition of 37 degrees C balance extraction, extract liquor by chloroform extraction, then the extract followed by analysis of GC-MS /MS. The method was simple, rapid, sensitive and accurate. The limits of quantitation (LOQ, S/N = 5) of cyclohexanone was 0.075 μg/mL, The spiked average recoveries ranged from 92% to 98%. The relative standard deviations (RSDs) of the method ranged from 1.01% to 1.61%, The method was simple, fast, sensitive and accurate, and may serve as a mass control method for residual DEHP in injection equipment.

Investigation on removal pathways of Di 2-ethyl hexyl phthalate from synthetic municipal wastewater using a submerged membrane bioreactor

Highly hydrophobic Di 2-ethyl hexyl phthalate (DEHP) is one of the most prevalent plasticizers in wastewaters. Since its half-life in biological treatment is around 25days, it can be used as an efficiency indicator of wastewater treatment plant for the removal of hydrophobic emerging contaminants. In this study, the performance of submerged membrane bioreactor was monitored to understand the effect of DEHP on the growth of aerobic microorganisms. The data showed that the chemical oxygen demand (COD) and ammonia concentration were detected below 10 and 1.0mg/L, respectively for operating conditions of hydraulic retention time (HRT)=4 and 6hr, sludge retention time (SRT)=140day and sludge concentration between 11.5 and 15.8g volatile solid (VS)/L. The removal efficiency of DEHP under these conditions was higher and ranged between 91% and 98%. Results also showed that the removal efficiency of DEHP in biological treatment depended on the concentration of sludge, as adsorption is the main mechanism of its removal. For the submerged membrane bioreactor, the pore size is the pivotal factor for DEHP removal, since it determines the amount of soluble microbial products coming out of the process. Highly assimilated microorganisms increase the biodegradation rate, as 74% of inlet DEHP was biodegraded; however, the concentration of DEHP inside sludge was beyond the discharge limit. Understanding the fate of DEHP in membrane bioreactor, which is one of the most promising and futuristic treatment process could provide replacement for conventional processes to satisfy the future stricter regulations on emerging contaminants.

Mono(2-ethylhexyl) phthalate induces apoptosis in p53-silenced L02 cells via activation of both mitochondrial and death receptor pathways

Mono(2-ethylhexyl) phthalate (MEHP) is one of the main metabolites of di(2-ethylhexyl) phthalate. The evidence shows that DEHP may exert its toxic effects primarily via MEHP, which is 10-fold more potent than its parent compound in toxicity in vitro. MEHP-induced apoptosis is mediated by either p53-dependent or -independent pathway. However, the detailed mechanism of its toxicity remains unclear. In this study, immortalized normal human liver cell line L02 was chosen, as an in vitro model of nonmalignant liver, to elucidate the role of p53 in MEHP-induced apoptosis. The cells were treated with MEHP (6.25, 12.50, 25.00, 50.00, and 100.00 μM) for 24 and 36 h, then small interfering RNA (siRNA) was used to specifically silence p53 gene of L02 cells. The results indicated that MEHP caused oxidative DNA damage and apoptosis in L02 cells were associated with the p53 signaling pathway. Further study found that MEHP (50.00 and 100.00 μM) induced apoptosis in p53-silenced L02 cells, along with the up-regulations of Fas and FasL proteins as well as increased the Bax/Bcl-2 ratio and Caspase 3, 8, and 9 activities. Additionally, both FasL inhibitor (AF-016) and Caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp- fluoromethylketone (Z-VAD-FMK) could prevent the cell apoptosis induced by MEHP. The findings suggested that MEHP-induced apoptosis in L02 cells involving a Caspases-mediated mitochondrial signaling pathway and/or death receptor pathway. p53 was not absolutely necessary for MEHP-induced L02 cell apoptosis.

An extraction process to recover vanadium from low-grade vanadium-bearing titanomagnetite

An extraction process to recover vanadium from low-grade vanadium-bearing titanomagnetite was developed. In this study, a mixed solvent system of di(2-ethylhexyl) phosphate (D2EHPA) and tri-n-butyl phosphate (TBP) diluted with kerosene was used for the selective extraction of vanadium from a hydrochloric acid leaching solution that contained low vanadium concentration with high concentrations of iron and impurities of Ca, Mg, and Al. In the extraction process, the initial solution pH and the phase ratio had considerable functions in the extraction of vanadium from the hydrochloric acid leaching solution. Under optimal extraction conditions (i.e., 30-40°C for 10min, 1:3 phase ratio (O/A), 20% D2EHPA concentration (v/v), and 0-0.8 initial solution pH), 99.4% vanadium and only 4.2% iron were extracted by the three-stage counter-current extraction process. In the stripping process with H2SO4 as the stripping agent and under optimal stripping conditions (i.e., 20% H2SO4 concentration, 5:1 phase ratio (O/A), 20min stripping time, and 40°C stripping temperature), 99.6% vanadium and only 5.4% iron were stripped by the three-stage counter-current stripping process. The stripping solution contained 40.16g/LV2O5,0.691g/L Fe, 0.007g/L TiO2, 0.006g/L SiO2 and 0.247g/L CaO. A V2O5 product with a purity of 99.12% V2O5 and only 0.026% Fe was obtained after the oxidation, precipitation, and calcination processes. The total vanadium recovered from the hydrochloric acid leaching solution was 85.5%.

Carryover Effects of Acute DEHP Exposure on Ovarian Function and Oocyte Developmental Competence in Lactating Cows

We examined acute exposure of Holstein cows to di(2-ethylhexyl) phthalate (DEHP) and its carryover effects on ovarian function and oocyte developmental competence. Synchronized cows were tube-fed with water or 100 mg/kg DEHP per day for 3 days. Blood, urine and milk samples were collected before, during and after DEHP exposure to examine its clearance pattern. Ovarian follicular dynamics was monitored through an entire estrous cycle by ultrasonographic scanning. Follicular fluids were aspirated from the preovulatory follicles on days 0 and 29 of the experiment and analyzed for phthalate metabolites and estradiol concentration. The aspirated follicular fluid was used as maturation medium for in-vitro embryo production. Findings revealed that DEHP impairs the pattern of follicular development, with a prominent effect on dominant follicles. The diameter and growth rate of the first- and second-wave dominant follicles were lower (P < 0.05) in the DEHP-treated group. Estradiol concentration in the follicular fluid was lower in the DEHP-treated group than in controls, and associated with a higher number of follicular pathologies (follicle diameter >25 mm). The pattern of growth and regression of the corpus luteum differed between groups, with a lower volume in the DEHP-treated group (P < 0.05). The follicular fluid aspirated from the DEHP-treated group, but not the controls, contained 23 nM mono(2-ethylhexyl) phthalate. Culturing of cumulus oocyte complexes in the follicular fluid aspirated from DEHP-treated cows reduced the proportion of oocytes progressing to the MII stage, and the proportions of 2- to 4-cell-stage embryos (P < 0.04) and 7-day blastocysts (P < 0.06). The results describe the risk associated with acute exposure to DEHP and its deleterious carryover effects on ovarian function, nuclear maturation and oocyte developmental competence.

Identification of di-2-ethylhexyl terephthalate (DEHTP) metabolites using human liver microsomes for biomonitoring applications

Di-2-ethylhexyl terephthalate (DEHTP), a structural isomer of the plasticizer di-2-ethylhexyl phthalate (DEHP), is used in food packaging and medical devices, among other applications, and is a potential replacement for DEHP and other ortho-phthalate plasticizers. Identifying sensitive and specific biomarkers of DEHTP is necessary to assess humans' background exposure to DEHTP. Using mass spectrometry, we investigated the metabolism of DEHTP by human liver microsomes to identify in vitro DEHTP metabolites. We unequivocally identified terephthalic acid (TPA) and mono-2-ethylhydroxyhexyl terephthalate (MEHHTP), using authentic standards, and tentatively identified mono-2-ethylhexyl terephthalate (MEHTP) and two other oxidative metabolites of DEHTP: mono-2-ethyloxohexyl terephthalate (MEOHTP), and mono-2-ethyl-5-carboxypentyl terephthalate (MECPTP) from their mass spectrometry fragmentation patterns. We also evaluated the formation of in vitro metabolites of DEHP. DEHTP and DEHP produced similar metabolites, but their metabolite profiles differed considerably. DEHTP metabolized to form TPA, a metabolite of several terephthalates, as the major in vitro metabolite, followed by MEHTP, MEHHTP, MEOHTP and MECPTP. MEHTP, MEHHTP, MEOHTP and MECPTP, which are specific metabolites of DEHTP, may be suitable biomarkers for assessing exposure to DEHTP. Nonetheless, data on the urinary excretion fraction and temporal stability of these metabolites, among other considerations, are needed to demonstrate their utility as exposure biomarkers.

A Means of Establishing and Justifying Binary Ethanol/Water Mixtures as Simulating Solvents in Extractables Studies

Ethanol/water mixtures are frequently used as simulating solvents in extractables studies. However, the basis for determining and justifying the right ethanol proportion in a simulating solvent for a particular drug product or solution has not been previously established.A solvent strength model has been developed in this study, based on the correlation between the levels of a model compound, di-(2-ethylhexyl) phthalate (DEHP), extracted from a reference source material, plasticized poly-(vinyl chloride) (PVC) resin, and the proportion of ethanol in ethanol/water extractions solvents. This model was established by experimentally investigating DEHP leaching and takes the form: [Formula: see text] If the level of DEHP extracted from the standard source PVC resin by a drug product is measured, then the level can be input into the above equation and the proper ethanol content of the appropriate simulating solvent can be determined.The model has been applied to certain drug products and additives used in drug products, and the proper ethanol/simulating solvents for these products have been established. Additionally, the leaching behavior revealed in this study has been established to be consistent with previously published research and a mechanism for the observed behavior has been proposed.

LAY ABSTRACT

Although ethanol/water mixtures are frequently used as simulating solvents in extractables studies, it is difficult to establish and justify what the right proportion of ethanol is for a particular drug product. A solvent strength model has been developed based on the leaching behavior of a model compound, di-(2-ethylhexyl) phthalate (DEHP), from a reference source material, plasticized poly-(vinyl chloride) (PVC). By measuring the level of DEHP leached into a drug product from the reference source material, one can use the model to calculate the correct ethanol proportion in the simulating solvent.Using this approach, ethanol/water proportions have been obtained for certain drug products. Additionally, the leaching profiles for DEHP obtained in this study were noted to be consistent with such profiles for other extractables from the PVC reference source material and with other investigations of ethanol/water as model stimulants.

Di-(2-ethylhexyl) phthalate metabolites in urine show age-related changes and associations with adiposity and parameters of insulin sensitivity in childhood

OBJECTIVES

Phthalates might be implicated with obesity and insulin sensitivity. We evaluated the levels of primary and secondary metabolites of Di-(2-ethylhexyl) phthalate (DEHP) in urine in obese and normal-weight subjects both before and during puberty, and investigated their relationships with auxological parameters and indexes of insulin sensitivity.

DESIGN AND METHODS

DEHP metabolites (MEHP, 6-OH-MEHP, 5-oxo-MEHP, 5-OH-MEHP, and 5-CX-MEHP), were measured in urine by RP-HPLC-ESI-MS. Traditional statistical analysis and a data mining analysis using the Auto-CM analysis were able to offer an insight into the complex biological connections between the studied variables.

RESULTS

The data showed changes in DEHP metabolites in urine related with obesity, puberty, and presence of insulin resistance. Changes in urine metabolites were related with age, height and weight, waist circumference and waist to height ratio, thus to fat distribution. In addition, clear relationships in both obese and normal-weight subjects were detected among MEHP, its products of oxidation and measurements of insulin sensitivity.

CONCLUSION

It remains to be elucidated whether exposure to phthalates per se is actually the risk factor or if the ability of the body to metabolize phthalates is actually the key point. Further studies that span from conception to elderly subjects besides further understanding of DEHP metabolism are warranted to clarify these aspects.

Sorption behavior of dibutyl phthalate and dioctyl phthalate by aged refuse

Sorption is a fundamental process controlling the transformation, fate, degradation, and biological activity of hydrophobic organic contaminants in the environment. We investigated the kinetics, isotherms, and potential mechanisms for the sorption of two phthalic acid esters (PAEs), dibutyl phthalate (DBP) and dioctyl phthalate (DOP), on aged refuse. A two-compartment first-order model performed better than a one-compartment first-order model in describing the kinetic sorption of PAEs, with a fast sorption process dominating. Both the Freundlich and Dubinin-Astakhov (DA) models fit the sorption isotherms of DBP and DOP, with the DA model being of a better fit over the range of apparent equilibrium concentrations. The values of the fitting parameters (n, b, E) of the PAEs suggest nonlinear sorption characteristics. Higher predicted partition coefficient values and saturated sorption capacity existed in refuse containing larger quantities of organic matter. The sorption capacity of DOP was significantly higher than that of DBP. PAE sorption was dependent on liquid phase pH. Desorption hysteresis occurred in PAE desorption experiments, especially for the long-chain DOP. PAEs may therefore be a potential environmental risk in landfill.

Adsorption of phthalic acid esters (PAEs) by amphiphilic polypropylene nonwoven from aqueous solution: the study of hydrophilic and hydrophobic microdomain

A kind of amphiphilic polypropylene nonwoven with hydrophilic and hydrophobic microdomain was prepared through electron beam induced graft polymerization and subsequent ring opening reaction and then utilized in the adsorption of phthalic acid esters (PAEs). To elucidate the superiority of such amphiphilic microdomain, a unique structure without hydrophilic part was constructed as comparison. In addition, the adsorption behaviors including adsorption kinetics, isotherms and pH effect were systematically investigated. The result indicated that the amphiphilic structure and the synergy between hydrophilic and hydrophobic microdomain could considerably improve the adsorption capacities, rate and affinity. Particularly the existence of hydrophilic microdomain could reduce the diffusion resistance and energy barrier in the adsorption process. These adsorption results showed that the amphiphilic PP nonwoven have the potential to be used in environmental application.

Primary neuronal-astrocytic co-culture platform for neurotoxicity assessment of di-(2-ethylhexyl) phthalate

Plastics such as polyvinyl chlorides (PVC) are widely used in many indoor constructed environments; however, their unbound chemicals, such as di-(2-ethylhexyl) phthalates (DEHP), can leach into the surrounding environment. This study focused on DEHP's effect on the central nervous system by determining the precise DEHP content in mice brain tissue after exposure to the chemical, to evaluate the specific exposure range. Primary neuronal-astrocyte co-culture systems were used as in vitro models for chemical hazard identification of DEHP. Oxidative stress was hypothesized as a probable mechanism involved, and therefore the total reactive oxygen species (ROS) concentration was determined as a biomarker of oxidative stress. In addition, NeuriteTracer, a neurite tracing plugin with ImageJ, was used to develop an assay for neurotoxicity to provide quantitative measurements of neurological parameters, such as neuronal number, neuron count and neurite length, all of which could indicate neurotoxic effects. The results showed that with 1 nmol/L DEHP exposure, there was a significant increase in ROS concentrations, indicating that the neuronal-astrocyte cultures were injured due to exposure to DEHP. In response, astrocyte proliferation (gliosis) was initiated, serving as a mechanism to maintain a homeostatic environment for neurons and protect neurons from toxic chemicals. There is a need to assess the cumulative effects of DEHP in animals to evaluate the possible uptake and effects on the human neuronal system from exposure to DEHP in the indoor environment.

Phthalate ester leachates in aquatic mesocosms: implications for ecotoxicity studies of endocrine disrupting compounds

Aquatic mesocosm experiments have become common throughout the fields of ecology and ecotoxicology. Mesocosm containers are often composed of plastic materials as these are lighter and cheaper than steel cattle tanks. Plastics may contain phthalate esters which may leach from containers, potentially confounding experiments via toxicity or endocrine disruption. The objective of this experiment was to determine the extent to which plastic containers (="tanks") used for mesocosms leach phthalates, and if there are significant differences between tank types and phthalate profiles. We investigated four tank types: fiberglass, polyethylene, poly-vinyl chloride, and polyethylene tanks containing an established aquatic community. We measured six common phthalate esters in water samples collected from each tank every 2 weeks for 8 weeks. There was a significant effect of tank type, time, and time x type interactions on phthalate ester concentrations. Di-(2-ethylhexyl) phthalate was the predominant congener measured in all samples. Fiberglass tanks had greater concentrations of dimethyl phthalate compared to other tank types (more than 600x larger concentration), but no other differences in phthalate profiles among tank types were evident. In addition, tanks with established communities had much higher concentrations of most phthalates at the 6 and 8 week timepoints. Our study confirms that mesocosm tanks of different materials leach phthalates starting immediately after they are filled and continuing for at least 8 weeks, but do so at different rates. Future ecotoxicity experiments should consider the potentially confounding effects of phthalates that may leach from tanks used in experimental mesocosms.

[Anaerobic biodegradation of phthalic acid esters (Paes) in municipal sludge]

Phthalic acid esters (PAEs), a class of organic pollutants with potent endocrine-disrupting properties, are widely present in municipal sludge. Study of PAEs biodegradation under different anaerobic biological treatment processes of sludge is, therefore, essential for a safe use of sludge in agricultural practice. In this study, we selected two major sludge PAEs, i.e. di-n-butyl phthalate (DBP) and di-(2-enthylhexyl) phthalate (DEHP), to investigate their biodegradation behaviors in an anaerobic sludge digestion system and a fermentative hydrogen production system. The possible factors influencing PAEs biodegradation in relation to changes of sludge properties were also discussed. The results showed that the biodegradation of DBP reached 99.6% within 6 days, while that of DEHP was 46.1% during a 14-day incubation period in the anaerobic digestion system. By comparison, only 19.5% of DBP was degraded within 14 days in the fermentative hydrogen production system, while no degradation was detected for DEHP. The strong inhibition of the degradation of both PAEs in the fermentative hydrogen production system was ascribed to the decreases in microbial biomass and ratios of gram-positive bacteria/gram-negative bacteria and fungi/ bacteria, and the increase of concentrations of volatile fatty acids (e. g. acetic acid, propionic acid and butyric acid) during the fermentative hydrogen-producing process.