Dimethyl Phthalate Research Articles

Limited effects of environmentally-relevant concentrations in seawater of dibutyl phthalate, dimethyl phthalate, bisphenol A, and 4-nonylphenol on the reproductive products of coral-reef organisms

Plastic additives (PAs) are chemical compounds incorporated into the plastic during the manufacturing process. Phthalate acid esters, bisphenols, and nonylphenols are all PAs found in marine environments and associated with endocrine-disrupting processes. However, our knowledge regarding the impact of endocrine-disrupting PAs on coral-reef organisms is limited. As reef population structure is directly linked to reproduction and larval settlement processes, interference with hormonal systems can impact coral-reef community structure, particularly if the effects of PAs differ among species. In the current study we exposed the reproductive products of four tropical coral-reef invertebrates to environmentally-relevant concentrations of four prevalent PAs in seawater: dibutyl phthalate (DBP), dimethyl phthalate, (DMP), 4-nonylphenol (4-NP), and bisphenol A (BPA), as well as to 103 higher laboratory concentrations of these PAs. Our results revealed that apart from the significant negative effect of the 1 μg/L of 4-NP on the settlement of the soft coral Rhytisma fulvum, none of the other tested materials demonstrated a significant effect on the exposed organisms at environmentally-relevant concentrations in seawater. The 4-NP high laboratory concentration (1000 μg/L), however, had significant negative effects on all the examined species. The high laboratory BPA concentration (1000 μg/L) significantly reduced fertilization success in the solitary ascidian Herdmaniamomus, up to its complete failure to reproduce. Moreover, the high laboratory DMP concentration (100 μg/L) had a significant negative effect on planulae settlement of the stony coral Stylophora pistillata. Our findings demonstrate the negative and selective effects of PAs on the development and reproduction of coral-reef organisms; and, specifically, the significant effect found following exposure to 4-NP. Consequently, if we aim to fully understand the impact of these contaminants on this endangered ecosystem, we suggest that the actual concentrations within the living organism tissues should be tested in order to produce relevant risk assessments for brooding-coral species.

Dimethyl phthalate inhibits the growth of Escherichia coli K-12 by regulating sugar transport and energy metabolism.

Dimethyl phthalate (DMP) is one of the most widely used plasticizers, and it is easily released into the environment, posing a threat to microbes. In this study, the impact of DMP on the uptake and metabolism of sugars in E. coli K-12 was assessed using proteomics, computational simulation analysis, transcriptome analysis, and sugar utilization experiments. DMP contamination inhibited the growth of E. coli K-12 and downregulated the expression of proteins in ATP-binding cassette (ABC) transporters and the phosphotransferase (PTS) system of E. coli K-12, which are primarily involved in the transmembrane transport of sugars. DMP formed a stable complex with sugar transporters and changed the rigidity and stability of the proteins. Furthermore, DMP treatment decreased the utilization of L-arabinose, glucose, D-xylose, and maltose. Moreover, carbon metabolism and oxidative phosphorylation were also downregulated by DMP. Our study shows that DMP reduces the uptake of sugars and ATP production and subsequently inhibits the growth of E. coli K-12.

Bisulfite-assisted surface Fenton-like degradation of dimethyl phthalate by ferrihydrite-H2O2 system

As a common plasticizer, phthalic acid esters (PAEs) have been widely employed to improve the flexibility and workability of polymetric materials, thus leading to their widespread distribution in soils and wastewater. Moreover, PAEs raised great public concerns due to their endocrine-disrupting effects, which could damage reproductive system and body development at low exposure dose. In the present study, a ferrihydrite-H2O2-bisulfite ternary system was developed to achieve efficient degradation of dimethyl phthalate (DMP). Our results showed that 86.6 % of total DMP could be removed within 240 min by the ferrihydrite-H2O2-bisulfite ternary system, in which the respective optimum concentration of ferrihydrite, H2O2 and bisulfite was set as 1.0 g/L, 5.0 mM and 2.0 mM. For comparison, negligible DMP removal was observed in the binary systems of ferrihydrite-H2O2, ferrihydrite-bisulfite and H2O2-bisulfite. Hydroxyl radical (•OH) was identified as the dominant reactive species for DMP degradation based on the results of electron paramagnetic resonance (EPR) analysis and free radicals quenching experiments. By complexing with iron species, bisulfite could accelerate the reduction of Fe(III) to Fe(II), thus increasing the generation of •OH by ∼4 times in the heterogeneous ferrihydrite-H2O2 system. Furthermore, ferrihydrite exhibited excellent recyclability without any modification as indicated by the negligible decrease in the catalytic degradation efficiency of DMP. Thus, in addition to efficient degradation of PAEs in wastewater, our study would shed light on the in-situ soil remediation technology on the basis of bisulfite-assisted heterogeneous Fenton-like reactions.

Separation of Mandelic Acid by a Reactive Extraction Method Using Tertiary Amine in Different Organic Diluents.

Mandelic acid is a valuable chemical that is commonly used in the synthesis of various drugs, in antibacterial products, and as a skin care agent in cosmetics. As it is an important chemical, various methods are used to synthesize and extract this compound. However, the yields of the used processes is not significant. A dilute aqueous solution is obtained when using several production methods, such as a fermentation, etc. In this study, the reactive extraction of mandelic acid from aqueous solutions using tri-n-octylamine extractant at 298.15 K was investigated. Dimethyl phthalate (DMP), methyl isobutyl ketone (MIBK), 2-octanone, 1-octanol, n-pentane, octyl acetate, and toluene were used as diluents. The batch extraction results of the mandelic acid experiments were obtained for the development of a process design. Calculations of the loading factor (Z), distribution coefficient (D), and extraction efficiency (E%) were based on the experimental data. The highest separation yield was obtained as 98.13% for 0.458 mol.L−1 of tri-n-octylamine concentration in DMP. The overall extraction constants were analyzed for the complex of acid-amine by the Bizek approach, including K11, K12, and K23.

Synergistic effect of ferrous ion-activated hydrogen peroxide and persulfate on the degradation of phthalates in aquatic environments by non-target analysis

Oxidative degradation of most recalcitrant organics in the wastewater by exciting the oxidative potential and high efficacy of economic and environmental compatible oxidants is currently an extensively studied field of research. In this study, an efficient phthalate esters (PAEs) degradation method utilizing dual oxidants persulfate (PS) and hydrogen peroxide in the presence of ferrous ions was developed with high removal efficiency, small oxidant dosage and wide pH range. Compared with the degradation efficiency of single systems including Fe2+/ H2O2 (40 %), PS (24 %) and Fe2+/PS (49 %) for dimethyl phthalate (DMP) degradation, the combining PS and H2O2 activated by Fe2+ is more effective, with the removal efficiency of 95 %. The synergistic effect of PS and H2O2 in the Fe2+-containing system on PAEs degradation was reflected by the degradation products determined by non-target analysis of various oxidation processes. The results showed that the degradation of DMP in two single oxidant systems was dominated by aromatic compounds via dealkylation, hydroxyl addition and decarboxylation, while DMP in the PS/H2O2/FeSO4 system was mainly deeply oxidized to aliphatic molecules through further dearomatization, which was vulnerable for the mineralization of DMP to CO2 and H2O. In addition, the EPR technique combined with DMPO captured SO4•− and •OH signals in the presence of the same Fe2+ and oxidant dosage, revealing that a higher intensity of ·OH and SO4•− generated in the combined oxidative process resulted in a high removal of DMP. This work lays the groundwork for recalcitrant organics removal to apply synergistic activation mode in the AOPs system.

Performance and integrated mathematical simulations of catalytic ozonation of dimethyl phthalate with activated carbon in continuous gas-liquid-solid reactors

How to predict the efficacy of heterogeneous catalytic ozonation reactors in reducing pollutants remains limited by complex multiphase systems. An integrated mathematical model of catalytic ozonation by activated carbon (AC) was developed based on hydrodynamics, mass transfer, adsorption, and reaction kinetics to simulate the performance of gas-liquid continuous flow catalytic ozonation reactors. A novel method was proposed reflecting the catalyst behavior to transform the complex gas-liquid-solid multiphase catalytic system into mass conservation equations for each component in gas and liquid phases. The catalyst activity is assumed to be mainly represented by adsorption and the transformation of ozone to hydroxyl radicals (•OH) by active groups on catalyst surface. A mathematical formulation of •OH generation was derived based on the Langmuir-Hinshelwood (LH) mechanism. The model simulation results obtained the concentration profiles of each component and achieved a satisfactory predictive power with error less than 20%, which in turn justified the modeling process. Sensitivity analysis showed that parameters including gas-liquid mass transfer coefficient, secondary reaction rate constant for indirect oxidation and catalyst capacity transfer coefficient have greater influence on simulation results. The optimal conditions for ozone utilization and pollutant degradation were obtained using the validated model simulations: catalyst dosage of 5 g/L, gas flow rate of 0.05 L/min, and initial ozone concentration of 50 mg/L. The results suggest that this mathematical model can provide useful information for design and optimization of catalytic ozonation reactors during industrial applications.

Enhanced photoelectrocatalytic performance for degradation of dimethyl phthalate over well-designed 3D hierarchical TiO2/Ti photoelectrode coupled dual heterojunctions

A novel A/R-TiO2 NSs/NRs photoelectrode was constructed through electrodeposition of anatase TiO2 nanosheets (A-TiO2 NSs) with highly exposed {001} facet onto the 1D upright rutile TiO2 nanorods (R-TiO2 NRs). At first, A/R-TiO2 NSs/NRs exhibited enhanced adsorption of dimethyl phthalate (DMP) due to the specific recognition between Lewis acid sites of {001} facet and Lewis basic DMP. NH3-TPD and Py-IR revealed that the Lewis acidity on the {001} facet of A-TiO2 NSs was much stronger than that of R-TiO2 NRs, demonstrating superior adsorption capacity to DMP. DFT theoretical calculations coupled with in-situ ATR-FTIR spectra were performed to investigate the binding adsorption behavior of DMP on A/R-TiO2 NSs/NRs. Secondly, the rapid separation of excited charges and strong oxidation of h+ were achieved by the synergistic effect of dual heterojunctions (A/R “phase heterojunction” and {111}/{110} “facet heterojunction”). The A/R-TiO2 NSs/NRs exhibited 100% degradation efficiency for the target pollutant DMP within 3 h, whose rate constant (k) was 18.02 × 10−3 min−1, 2.16 times that of pure R-TiO2 NRs. In real wastewater application, A/R-TiO2 NSs/NRs achieved 93.8% elimination of DMP during 4 h and preserved excellent stability after 5 cycles, promising a wide-range of applications in water environment remediation.

Development of a magnetic sorbent based on synthesis of MOF-on-MOF composite for dispersive solid-phase microextraction of five phthalate esters in bottled water and fruit juice samples

A straightforward sample preparation method based on dispersive micro solid-phase extraction was developed to simultaneous extract phthalate esters in bottled water and fruit juice samples. The novel and efficient sorbent for the extraction of phthalate esters was prepared by combining three components, including ZIF-8 @ ZIF-67 as a MOF-on-MOF and Fe3O4 nanoparticles as a magnet component, and SiO2 using the sol–gel technique. A simplex centroid mixture design was generated to optimize the value of sorbent components. The optimum sorbent was characterized by investigating the FTIR spectra, FE-SEM images, EDX pattern, VSM image, and XRD pattern. Besides, practical factors in the microextraction procedure were optimized using one factor at a time and experimental design (definitive screening design and central composite design). The method was linear for determining dimethyl phthalate, diethyl phthalate, di-n-butyl phthalate, benzyl butyl phthalate, and di-isobutyl phthalate were 0.03–25, 0.03–25, 0.05–30, 0.07–30, and 0.05–30 ng mL−1 with determination coefficients (R2) higher than 0.9907, respectively. Intra-day and inter-day RSDs were in the ranges of 3.18–4.97 % and 5.16–6.35 %, respectively. Also, the limit of detections and limit of quantitation for the analyte determination were lower than 0.02 and 0.07 ng mL−1, respectively. Analysis of two mineral water samples, drinking water, and two fruit juice samples (apple and grape) packed in bottles as real samples using the procedure indicated that the method is satisfactory for measuring phthalate esters due to proper recoveries and relative standard deviations in the range of 84.0–106.0 % and 3.57–8.33 %, respectively.

Optimized LC-MS/MS method for simultaneous determination of endocrine disruptors and PAHs bound to PM2.5: Sources and health risk in Indo-Gangetic Plain

Airborne particulate matter (PM) is a serious health threat when it is bound to hazardous pollutants like phthalic acid esters (PAEs) (endocrine disruptors) and polycyclic aromatic hydrocarbons (PAHs). In this study, an optimized method was developed and validated for the simultaneous screening and quantification of PAEs (dimethyl phthalate (DMP), diethyl phthalate (DEP), benzyl butyl phthalate (BBP), dibutyl phthalate (DBP), bis (2-ethyl hexyl) phthalate (DEHP), bis(2-ethylhexyl) adipate (DEHA), di-n-octyl phthalate (DNOP)) and PAHs (benzo[a]anthracene (B[a]A), benzo[b]fluorenthene (B[b]F), benzo[k]fluorenthene (B[k]F), benzo[a]pyrene (B[a]P), dibenzo[ah]anthracene (D[ah]A), benzo[ghi]perylene (B[ghi]P), and indeno[1,2,3-cd]pyrene (IND)) bound to ambient PM2.5 using liquid chromatography coupled to electrospray ionization tandem mass spectrometer (LC-ESI-MS/MS). The developed method exhibited excellent linearity (r2 > 0.99), precision error less than 10%, good recovery percentages (90%–120%, except for DMP ≈ 65%). After the validation, this method was deployed to investigate the seasonal variation and source identification of targeted compounds bound to ambient PM2.5 at a measurement site in the North West Indo-Gangetic Plain (NWIGP). In this study, the most abundant PAE and PAH are DEHP (17.94 ng m−3) and B[b]F (36.13 ng m−3), respectively. Measured concentrations of B[a]P, Group 1 carcinogen (4.66 ng m−3) had exceeded the National Ambient Air Quality Standards, India (1 ng m−3). Diagnostic ratios (DRs) revealed that fossil fuel/diesel combustions are the major emission sources of PAHs in summer and monsoon while biomass/coal combustions in winter season at the sampling site. Further, incremental lifetime cancer risk (ILCR) for adults and children due to exposure to PM2.5 bound DEHP (adults: 0.3678 × 10−6 and children: 0.8792 × 10−6) and B[a]Peq (adults: 1.40 × 10−5 and children: 3.272 × 10−5) were estimated. Estimated ILCR values for B[a]Peq exceeded the threshold value (1 × 10−6) set by USEPA. Findings in this study reveal that the health risk due to exposure to PAEs and PAHs bound to PM2.5 should be of concern.

Dimethyl phthalate destroys the cell membrane structural integrity of Pseudomonas fluorescens.

A Gram-negative bacteria (Pseudomonas fluorescens) was exposed to different concentrations (0, 20, and 40 mg/L) of dimethyl phthalate (DMP) for 8 h, and then Fourier transform infrared spectroscopy (FTIR) analysis, lipopolysaccharide content detection, analysis of fatty acids, calcein release test, proteomics, non-targeted metabolomics, and enzyme activity assays were used to evaluate the toxicological effect of DMP on P. fluorescens. The results showed that DMP exposure caused an increase in the unsaturated fatty acid/saturated fatty acid (UFA/SFA) ratio and in the release of lipopolysaccharides (LPSs) from the cell outer membrane (OM) of P. fluorescens. Moreover, DMP regulated the abundances of phosphatidyl ethanolamine (PE) and phosphatidyl glycerol (PG) of P. fluorescens and induced dye leakage from an artificial membrane. Additionally, excessive reactive oxygen species (ROS), malondialdehyde (MDA), and changes in antioxidant enzymes (i.e., catalase [CAT] and superoxide dismutase [SOD]) activities, as well as the inhibition of Ca2+-Mg2+-ATPase and Na+/K+-ATPase activities in P. fluorescens, which were induced by the DMP. In summary, DMP could disrupt the lipid asymmetry of the outer membrane, increase the fluidity of the cell membrane, and destroy the integrity of the cell membrane of P. fluorescens through lipid peroxidation, oxidative stress, and ion imbalance.

The values of ΔfHo298.15 and So298.15 of the radicals formed by the abstraction of H atom from the p‐Benzylphenol and Dimethyl Phthalate

AbstractIn the present work, the thermochemical properties of the radicals (Yj), formed by abstraction of H atom from Dimethyl Phthalate (o‐Ph(C(O)OCH3)2) and p‐Benzylphenol (p‐PhCH2PhOH), are determined at the B3LYP/6‐311++G(d,p) (j = 1), M06‐2X/6‐311++G(d,p) (j = 2), and RO/CBS‐4 M (j = 3 and 4) levels of theory. Their calculated values of Ho298.15(Yj, CALC) are used for the determination of thermochemistry of atomization (ΔrHo298.15(Yj,CALC)atom) and homodesmotic (ΔrHo298.15((RYi)j,CALC)REAC) reactions of considered radicals. The reported calibration dependencies are used for the correction of calculated values and determination of the most consistent and accurate values of ΔfHo298.15 and ΔfGo298.15. It is found that o‐CH3OC(O)PhC(O)OCH2∙ (1C), p‐PhC∙HPhOH (1D) and p‐PhCH2PhO∙ (3D) are the most thermochemically stable structures. The intersection of reported 3SEj (= 3σj) intervals of ΔfHo298.15(1Cj,CORR)atom of atomization results the value of ΔfHo298.15(1C,CORR)MEAN = −405.1 ± 1.3 kJ/mol (±3SEY = 3σY), while, the most accurate values of ΔfHo298.15(1D and 3D,CORR)REACMEAN = 114.7 ± 0.4 and 135.8 ± 5 kJ/mol (± 3SEYREAC = 3σYREAC) are determined using the values ΔfHo298.15((RYi)j,CORR)REAC of homodesmotic reactions. The values of ΔfGo298.15, determined using the values of ΔfHo298.15 and So298.15 of these radicals, demonstrate that the exothermic reaction (17) HO2∙ + p‐PhCH2PhOH → H2O2 + p‐PhC∙HPhOH (–22.9 kJ/mol) is thermochemically more favorable than the reaction (19) HO2∙ + p‐PhCH2PhOH → H2O2 + p‐PhCH2PhO∙ (–1.8 kJ/mol). However, the value of kT(17) = 1.63 × 10–14(T/298.15)3.6e(‐6282/T), calculated using the VTST, is kinetically more favorable at elevated temperatures, while, the reaction (19) (kT(19) = 1.04×10–16(T/298.15)2.17e(–5207/T)) is more important at T < 200 K. The thermochemical properties of these radicals, as well as the calculated rate constants of their formation in reactions of HO2∙ radicals with p‐Benzylphenol, are reported for the first time.

Phthalates released from microplastics inhibit microbial metabolic activity and induce different effects on intestinal luminal and mucosal microbiota

The intestine is not only the main accumulation organ of microplastics (MPs), but also the intestinal environment is very conductive to the release of additives in MPs. However, the kinetics of release process, influence factors, and the related effects on gut microbiota remain largely unknown. In this study, a mucosal-simulator of the human intestinal microbial ecosystem (M-SHIME) was used to investigate the influence of gut microbiota on the release of phthalates (PAEs) from MPs and the effects of MPs on the intestinal luminal microbiota and mucosal microbiota. We found that di-(2-ethylhexyl) phthalate (DEHP), di-n-butyl phthalate (DBP), and dimethyl phthalate (DMP) were the dominant PAEs released in the gut. Gut microbiota accelerated the release of PAEs, with the time to reach the maximum release was shortened from 7 days to 2 days. Moreover, MPs induced differential effects on luminal microbiota and mucosal microbiota. Compared with mucosal microbiota, the luminal microbiota was more susceptible to the leaching of PAEs from MPs, as evidenced by more microbiota alterations. MPs also inhibited the metabolic activity of intestinal flora based on the reduced production of short chain fatty acids (SCFA). These effects were mainly contributed by the release of PAEs. Acidaminococcus and Morganella were simultaneously correlated to the release of PAEs and the inhibition of metabolic activity of intestinal microbiota and can be used as indicators for the intestinal exposure of MPs and additives.

Determination and Risk Associated with Phthalic Esters Distribution from the Ekpan River, Effurun, Delta State, Nigeria

Phthalates are additives or plasticizers added to make plastics soft. However, they could leach into the environment and cause harm to human health when contacted. Sites along the Ekpan river have been used for open dumping of refuse. The river also serves as a point source for the disposal of effluents from the Warri Refinery and Petrochemical Company Limited (WRPC). Hence, the need for a preliminary study of phthalates across the river system. Surface water samples were collected from six points along the Ekpan river. Phthalates were extracted using USEPA standard method 3535 and EPA method 8061. Gas Chromatography-Mass Spectrometer (GC-MS) was used for the analysis of six PAEs including di-n-butyl phthalate (DnBP or DPX), butyl benzyl phthalate (BBP), di(2-Ethylhexyl) phthalate (DEHP), di-n-octyl phthalate (D-n-OP)), Dimethyl phthalate (DMP), and Diethyl phthalate (DEP) in the river system. Analysis of phthalates in the Ekpan river system showed that DEP across the Effurun river system ranged from 4.22 – 13.81 μg/L, DPX; 3.03 – 11.5 μg/L, BBP; 0.11–1.39 μg/L, DEHP; 0.12 – 3.33 μg/L. D-n-OP and DMP were below the limit of detection of the analytical instrument used (0.1 μg/L). The distribution of PAEs along the network of the river revealed that the sampling sites in the urban region were more contaminated with PAEs due to urbanization and an increase in population across the river network. Human health risk assessment revealed that the hazard quotient (HQ) for DEP, DPX, DEHP, and D-i-NP were below 1, indicating an acceptable risk of PAEs via ingestion or bathing of the river water. In addition, the Hazard Index (HI) via ingestion and bathing of the river water was less than 1 indicating acceptable risks. According to this study, these PAEs congeners are safe for toddlers, adolescents, and adults to eat and bathe in tap water. Even DEHP, the only PAEs congener designated as a carcinogenic agent by WHO, was shown to have a tolerable cancer risk. These findings indicate that there is no harm to children, adolescents, and adults from DEHP in the river water studied.

Electrospinning of ZIF-67 Derived Co-C-N Composite Efficiently Activating Peroxymonosulfate to Degrade Dimethyl Phthalate

In this work, an efficient cage-core peroxymonosulfate (PMS) catalyst was synthesized by applying an electrospinning–calcination process to the cobalt–zeolitic imidazole framework (ZIF-67) crystals for the catalytic degradation of dimethyl phthalate (DMP). The morphology and surface properties of the synthesized materials (ZIF-67, Z600 and ZP400/600/800) were well characterized. ZP600 showed great performance for the catalytic degradation of DMP in the initial pH range of 7.5–10.5. The removal rate of DMP could reach 90.4% in 60 min under optimum dosages of reagents (catalyst = 0.1 g/L, PMS = 0.5 mM, DMP = 6 ppm), and the mineralization degree of contaminant could reach 65%. By quenching experiments, it was determined that sulfate radical (SO4−·) and hydroxyl radical (·OH) dominated the degradation process. Moreover, due to the good magnetism, ZP600 could be easily separated from liquid and showed great reusability in five-cycle reaction experiments. Surprisingly, with the cover of cage-like polyacrylonitrile (PAN) fibers, the cobalt leaching amount of ZP600 decreased by about 87%. This study would expand the application of the electrospinning process in the development of functional materials for water purification.

Effect of storage on the levels of phthalates in high-density polyethylene (HDPE) film-packaged drinking water

High-Density Polyethylene (HDPE)-packaged water is a popular choice for urban potable water across Africa. However, the sources and fate of priority chemical contaminants have not been adequately reported. The present study seeks to determine the effect of storage and labelling on the levels of phthalates - dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), benzyl butyl phthalate (BBP) and di(2-hexylethyl) phthalate (DEHP) - in HDPE packaged water. Printed and unprinted 500 mL packet samples, treated water and raw water samples were collected from two major companies in Accra and stored at three temperature levels for 28 days. Phthalates were extracted and pre-concentrated for analysis by GC–MS weekly. The results indicated that phthalates loading became detectable within the first 7 days of incubation, with printed samples showing higher concentrations than unprinted samples at every incubation temperature. The highest concentration was recorded for BBP (1.03 μg/L between a lower and upper confidence limits of 0.62 μg/L and 1.42 μg/L). Temperature significantly affected the concentration of DMP for printed packets (p-value = 0.05) and unprinted samples (p-value = 0.06), BBP across all samples, and DEHP in printed samples (p-value = 0.06). On the other hand, storage duration significantly affected the concentration of BBP across all samples. There was a very strong correlation between printing and the concentration of phthalates in the water samples (p-values <0.001) across the storage temperatures. Effect size analysis established significant differences between site-specific printed and unprinted samples. The present study revealed weak interactions between the selected phthalates and the HDPE matrix, and recommends alternative packaging that can restrict the presence of phthalates and other priority chemicals in plastic packaged drinking water.

Analysis of the performance of the efficient di-(2-ethylhexyl) phthalate-degrading bacterium Rhodococcus pyridinovorans DNHP-S2 and associated catabolic pathways

The widespread use of plastic has led to the global occurrence of phthalate esters (PAEs) pollution. PAEs can be effectively removed from polluted environments by microbe-mediated degradation. Di-(2-ethylhexyl) phthalate (DEHP) has the highest residual concentration in agricultural soil-contaminated areas compared to other PAEs in most of China. The Rhodococcus pyridinovorans DNHP-S2 microbial isolate identified was found to efficiently degrade DEHP. Within a 72 h period, the bacteria were able to degrade 52.47% and 99.75% of 500 mg L−1 DEHP at 10 °C and 35 °C, respectively. Dimethyl phthalate (DMP) was first identified as an intermediate metabolite of DEHP, which is different from the previously reported DEHP catabolic pathway. Genomic sequencing of DNHP-S2 identified benzoate 1,2-dioxygenase and catechol 2,3/1,2-dioxygenase as potential mediators of DEHP degradation, consistent with the existence of two downstream metabolic pathways governing DEHP degradation. Three targets DEHP metabolism-related enzymes were found to be DEHP-inducible at the mRNA level, and DNHP-S2 was able to mediate the complete degradation of DEHP at lower temperatures, as confirmed via RT-qPCR. DNHP-S2 was also found to readily break down other PAEs including DMP, di-n-butyl phthalate (DBP), di-n-octyl phthalate (DnOP), and n-butyl benzyl phthalate (BBP). Together, these results thus highlight DNHP-S2 as a bacterial strain with great promise as a tool for the remediation of PAE pollution. In addition to providing new germplasm and genetic resources for use in the context of PAE degradation, these results also offer new insight into the potential mechanisms whereby PAEs undergo catabolic degradation, making them well-suited for use in PAE-contaminated environments.

Dietary exposure and risk assessment of phthalic acid esters through a total diet study in Shenzhen, South China

Phthalic acid esters (PAEs) are typical endocrine disruptors which are ubiquitous contaminants. Human exposure to PAEs is through multiple routes of which the diet is recognised as the main source of daily intake. The aim of this study was to evaluate the dietary exposure to PAEs of residents in Shenzhen (China) through a total diet study and assess the potential health risk. A total of 16 different phthalate esters in samples of 12 composite food groups were determined by GC–MS. The main dietary sources of PAE exposure among adult residents in Shenzhen were potatoes (21%), eggs (21%), meat (15%) and aquatic products (14%). The median total dietary exposure to PAEs in Shenzhen residents was 7780 ng kg−1 bw d−1, and the hazard quotients (HQ) of dimethyl phthalate (DMP), diethyl phthalate (DEP), di-isobutyl phthalate (DIBP), dibutyl phthalate (DBP) and di-2-ethylhexyl phthalate (DEHP) were 0.09, 0.06, 0.07, 0.10 and 0.03, respectively. Therefore, the risks from dietary PAE exposure were low. However, with the increasing use of PAEs and their accumulation in the environment, the probability of PAEs entering the food chain is gradually increasing and, therefore, PAEs should be strictly controlled and regularly monitored.

Relationships among phthalate exposure, oxidative stress, and insulin resistance in young military soldiers: A cumulative risk assessment and mediation approach.

Epidemiological studies concerning whether oxidative stress mediates phthalate exposure-insulin resistance (IR) associations in young adults are limited. Therefore, we investigated this potential mediation by using a cumulative risk approach involving daily intake (DI) and a hazard index (HIRfD). The participants were 391 Taiwanese military personnel. This study measured their IR (as homeostatic model assessment of estimated IR [HOMA-IR]), levels of oxidative stress biomarkers (8-hydroxy-2-deoxyguanosine, 8-nitroguanine, 8-iso-prostaglandin F2α, and N-acetyl-S-[tetrahydro-5-hydroxy-2-pentyl-3-furanyl]-L-cysteine [HNE-MA]), the sum of these four biomarkers (ΣOS), and urinary phthalate metabolite concentrations. The HIRfD was estimated on the basis of urinary levels of phthalate metabolite, and the DI of five phthalates was determined: dimethyl phthalate, benzyl butyl phthalate (BBzP), diethyl phthalate, dibutyl phthalate (DBP), and di (2-ethylhexyl) phthalate (DEHP). Logistic regression models were employed to explore associations among DI, HIRfD, oxidative stress biomarkers, and HOMA-IR values. The role played by oxidative stress in the phthalate exposure-HOMA-IR association was determined using mediation analysis. We discovered positive associations between high DI of DBP, BBzP, and DEHP; high HIRfD; and high ΣOS. High ΣOS and HNE-MA were associated with a higher likelihood of a high HOMA-IR value. Mediation analysis indicated that high ΣOS and HNE-MA were significant mediators of the associations between phthalates and IR. Oxidative stress may partially mediate the phthalate-IR relationship in young adults.

Ultrasonic treatment enhances the formation of oxygen vacancies and trivalent manganese on α-MnO2 surfaces: Mechanism and application

Catalytic activity is the main obstacle limiting the application of peroxymonosulfate (PMS) activation on transition metal oxide catalysts in organic pollutant removal. Herein, ultrasonic treatment was applied to α-MnO2 to fabricate a new u-α-MnO2 catalyst for PMS activation. Dimethyl phthalate (DMP, 10 mg/L) was almost completely degraded within 90 min, and the pseudofirst-order rate constant for DMP degradation in the u-α-MnO2/PMS system was ∼7 times that in the initial α-MnO2/PMS system. The ultrasonic treatment altered the crystalline and pore structures of α-MnO2 and produced defects on the u-α-MnO2 catalyst. According to the XPS, TG, and EPR results, higher contents of trivalent Mn and oxygen vacancies (OVs) were produced on the catalyst surfaces. The OVs induced the decomposition of PMS to produce 1O2, which was identified as the main reactive oxygen species (ROS) responsible for DMP degradation. The u-α-MnO2 catalyst presented great reusability, especially by ultrasonic regeneration of OVs toward the used catalyst. This study provides new insights into regulating OVs generation and strengthening catalyst activity in the PMS activation process for its application in water purification.

Removal of Phthalates from Water by Unconventional La‐based/WO3 Photocatalysts

AbstractLa2O2CO3‐WO3 composites were here proposed as unconventional photocatalysts for the removal of phthalates in water. The high sorption properties of the lanthanum dioxide carbonate allowed a strong adsorption of the phthalates which facilitated the following solar photocatalytic degradation, further boosted by the addition of small amounts of WO3 (1 wt%). On the contrary, a higher content of WO3 had a detrimental effect due to the covering of the surface sites of La2O2CO3 that inhibited the adsorption process. This double mechanism of strong adsorption‐photocatalytic oxidation led, after 6 h of solar irradiation, to 67 % and 63 % dimethyl phthalate and di(2‐ethylhexyl)phthalate degradation, respectively. The phthalates were degraded to less persistent pollutants that, however, were completely removed after 9 h of irradiation. The La2O2CO3‐WO3 system appears promising for its application in the removal of the emerging contaminants from water.