Efficient remediation of di-(2-ethylhexyl) phthalate and plant-growth promotion with the application of a phosphate-solubilizing compound microbial agent.

The ecotoxic endocrine-disrupting chemical di-(2-ethylhexyl) phthalate (DEHP) is ubiquitous in agricultural soil, posing a serious threat to human health. Here, we report efficient soil-borne DEHP degradation and plant growth promotion by a microbial organic fertilizer GK-PPB prepared by combining a recycled garden waste-kitchen waste compost product with ternary compound microbial agent PPB-MA, composed of Penicillium oxalic MB08F, Pseudomonas simiae MB751, and Bacillus tequilensis MB05B. The combination of MB08F and MB751 provided synergistic phosphorus solubilization, and MB05B enhanced the DEHP degradation capacity of MB08F via bioemulsification. Under optimal conditions (25.70 °C and pH 7.62), PPB-MA achieved a 96.81 % degradation percentage for 1000 mg L-1 DEHP within 5 days. The degradation curve followed first-order kinetics with a half-life of 18.24 to 24.76 h. A complete mineralization pathway was constructed after identifying the degradation intermediates of 2H-labeled DEHP. Evaluation in Caenorhabditis elegans N2 showed that PPB-MA eliminated the ecological toxicity of DEHP. A pakchoi (Brassica chinensis L.) pot experiment demonstrated that GK-PPB promoted phosphorus solubilization and plant growth, reduced soil DEHP residue, and decreased DEHP accumulation in pakchoi, suggesting its potential practical utility in environmentally responsible and safe cultivation of vegetables.

Uptake and accumulation of di(2-ethylhexyl) phthalate (DEHP) in a soil-ginseng system and toxicological mechanisms on ginseng (Panax ginseng C.A. Meyer).

Di(2-ethylhexyl) phthalate (DEHP) is regarded as a priority environmental pollutant. This study explored the adsorption and accumulation of DEHP within the ginseng-soil system and the mechanism of DEHP toxicity to ginseng (Panax ginseng C.A. Meyer). Under exposure to 22.10 mg/kg DEHP in soil, DEHP mainly accumulated in ginseng leaves (20.28 mg/kg), stems (4.84 mg/kg) and roots (2.00 mg/kg) after 42 days. The oxidative damage, metabolism, protein express of ginseng were comprehensively measured and analyzed. The results revealed that MDA presented an activation trend in ginseng stems and leaves after 42 days of DEHP exposure, while the opposite trend was observed for POD. Levels of ginsenoside metabolites Rg2, Rg3, Rg5, Rd, Rf and CK decreased in the ginseng rhizosphere exudates under DEHP stress. Further investigations revealed that DEHP disrupts ginsenoside synthesis by inducing glycosyltransferase (GS) and squalene synthase (SS) protein interactions. Molecular docking indicated that DEHP could stably bind to GS and SS by intermolecular forces. These findings provide new information on the ecotoxicological effect of DEHP on ginseng root.

Neonatal di-(2-ethylhexyl)phthalate exposure induces permanent alterations in secretory CRH neuron characteristics in the hypothalamus paraventricular region of adult male rats.

Corticotrophin-releasing hormone (CRH) neurons in the hypothalamic paraventricular nucleus (PVN) play a critical role in the modulation of the hypothalamic-pituitary-adrenal (HPA) axis. Early-life exposure to di-(2-ethylhexyl) phthalate (DEHP) has been associated with an increased risk of developing psychiatric disorders in adulthood. The present work was designed to explore the impact of neonatal exposure to DEHP on adult PVN CRH neuronal activity. DEHP or vehicle was given to male rat pups from PND16 to PND22. Then, anxiety-like behaviors, serum corticosterone and testosterone, immunohistochemistry, western blotting, fluorescence in situ hybridization and acute ex vivo slice electrophysiological recordings were used to evaluate the influence of DEHP on adult PVN secretory CRH neurons. Neonatal DEHP-exposed rats exhibited enhanced anxiety-like behaviors in adults, with an increase in CORT. Secretory CRH neurons showed higher spontaneous firing activity but could be inhibited by GABAAR blockers. CRH neurons displayed fewer firing spikes, prolonged first-spike latency, depolarizing shifts in GABA reversal potential and strengthened GABAergic inputs, as indicated by increases in the frequency and amplitude of sIPSCs. Enhancement of GABAergic transmission was accompanied by upregulated expression of GAD67 and downregulated expression of GABABR1, KCC2 and GAT1. These findings suggest that neonatal exposure to DEHP permanently altered the characteristics of secretory CRH neurons in the PVN, which may contribute to the development of psychiatric disorders later in life.

Lycopene prevents Di-(2-ethylhexyl) phthalate-induced mitophagy and oxidative stress in mice heart via modulating mitochondrial homeostasis.

Di-(2-ethylhexyl) phthalate (DEHP) is a plasticizer that is easily found in the environment. Excessive daily exposure of it may lead to an increased risk of cardiovascular disease (CVD). Lycopene (LYC), as a natural carotenoid, has been shown to have the potential to prevent CVD. However, the mechanism of LYC on cardiotoxicity caused by DEHP exposure is unknown. The research was aimed to investigate the chemoprotection of LYC on the cardiotoxicity caused by DEHP exposure. Mice were treated with DEHP (500 mg/kg or 1,000 mg/kg) and/or LYC (5 mg/kg) for 28 d by intragastric administration, and the heart was subjected to histopathology and biochemistry analysis. The results indicated that DEHP caused cardiac histological alterations and enhanced the activity of cardiac injury indicators, and interfered with mitochondrial function and activating mitophagy. Notably, LYC supplementation could inhibit DEHP-induced oxidative stress. The mitochondrial dysfunction and emotional disorder caused by DEHP exposure were significantly improved through the protective effect of LYC. We concluded that LYC enhances mitochondrial function by regulating mitochondrial biogenesis and dynamics to antagonize DEHP-induced cardiac mitophagy and oxidative stress.

Lycopene ameliorates DEHP exposure-induced renal pyroptosis through the Nrf2/Keap-1/NLRP3/Caspase-1 axis.

Di (2-ethylhexyl) phthalate (DEHP) is commonly used as a plasticizer in plastic products, and due to its unique chemical composition, it frequently dissolves and enters the environment. Lycopene as a natural carotenoid has been shown to have powerful antioxidant capacity and strong kidney protection. This study aimed to investigate the role of the interplay between oxidative stress and the classical pyroptosis pathway in LYC alleviating DEHP-induced renal injury. ICR mice were given DEHP (500 mg/kg/d or 1000 mg/kg/d) and/or LYC (5 mg/kg/d) for 28 days to explore the underlying mechanisms of this hypothesis. Our results indicated that DEHP caused the shedding of renal tubular epithelial cells, increased the content of kidney injury molecule-1 (Kim-1) and neutrophil gelatinase-associated lipocalin (NGAL) in the tissue, the decrease of antioxidant activity markers and the increase of oxidative stress indexes. It is gratifying that LYC alleviates DEHP-induced renal injury. The expression of nuclear factor erythrocyte 2-related factor 2 (Nrf2) and its downstream target genes is improved in DEHP induced renal injury through LYC mediated protection. Meanwhile, LYC supplementation can inhibit DEHP-induced Caspase-1/NLRP3-dependent pyroptosis and inflammatory responses. Taken together, DEHP administration resulted in nephrotoxicity, but these changes ameliorated by LYC may through crosstalk between the Nrf2/Keap-1/NLRP3/Caspase-1 pathway. Our study provides new evidence that LYC protects against kidney injury caused by DEHP.

Protective effect of Lycium barbarum polysaccharide on di-(2-ethylhexyl) phthalate-induced toxicity in rat liver.

Di-(2-ethylhexyl)-phthalate (DEHP) is the most commonly used plasticizer and it has been a ubiquitous environmental contaminant which affects health. The purpose of this study was to investigate the protective effect of the Lycium barbarum polysaccharide (LBP) at dosages of 100, 200, and 300 mg/kg bw on DEHP-induced (3000 mg/kg) toxicity in rat liver through a 28-day animal experiment. The results showed that LBP attenuated oxidative stress slightly by lowering the production of ROS and improving the activity of SOD and GSH-Px in liver and serum of DEHP treatment rats. At the same time, the levels of PXR, CYP450, CYP2E1, CYP3A1, UGT1, and GST were reduced after LBP treatment. Moreover, LBP decreased the mRNA expression of PXR, UGT1, and GST significantly. These findings suggested that LBP might ameliorate DEHP-induced liver injury by down-regulating the expression of PXR in liver, further down-regulating the downstream phase I and II detoxification enzymes, thus reducing the damage caused by DEHP. Therefore, LBP may have the potential to become an auxiliary therapeutic agent as a natural ingredient of health food.

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.

Removal of spilled petroleum in industrial soils by spent compost of mushroom Pleurotus pulmonarius.

Two batches of oil-contaminated soil collected from an industrial area and one pile of oil-contaminated soil in a power plant were treated by the spent compost of mushroom Pleurotus pulmonarius (SMC). SMC contained macronutrients for biostimulation, possessed 1.0-1.5 U mg(-1) laccase and 0.8-0.9 U mg(-1) manganese peroxidase for biodegradation and harboured (11+/-3)x10(7) cfu g(-1) bacteria and (56+/-9)x10(4) cfu g(-1) fungi for bioaugmentation. In off-site ex situ bioremediation, the industrial area soil was contaminated with organic 5.4-6.9 g kg(-1) total petroleum hydrocarbons (TPH), 14.5-19.0 g kg(-1) oil and grease and 95-99 mg kg(-1) di(2-ethylhexyl) phthalate (DEHP) and inorganic 104-136 mg kg(-1) Cu, 430-691 mg kg(-1) Pb and 477-578 mg kg(-1) Zn. The removal by 3% SMC amendment applied twice accounted for 56-64%, 31-33% and 51-54% disappearance of the TPH, oil and grease and DEHP contaminants, respectively. For the latter soil, one 0.3% SMC application removed 40-45% of the initial 1.2+/-0.2 g kg(-1) TPH and 4.0+/-0.6 g kg(-1) oil and grease in 22 d. Further using four bacteria and four fungi inoculated onto the sterilized soil samples, samples with greater removal of the pollutants bore larger microbial populations. Thus SMC simultaneously degrades petroleum residues and reduces toxicity in less than a month.

Degradation of phthalate esters in an activated sludge wastewater treatment plant.

Efficient removal of phthalate esters (PE) in wastewater treatment plants (WWTP) is becoming an increasing priority in many countries. In this study, we examined the fate of dimethyl phthalate (DMP), dibutyl phthalate (DBP), butylbenzyl phthalate (BBP), and di-(2-ethylhexyl) phthalate (DEHP) in a full scale activated sludge WWTP with biological removal of nitrogen and phosphorus. The mean concentrations of DMP, DBP, BBP, and DEHP at the WWTP inlet were 1.9, 20.5, 37.9, and 71.9 microg/L, respectively. Less than 0.1%, 42%, 35%, and 96% of DMP, DBP, BBP, and DEHP was associated with suspended solids, respectively. The overall microbial degradation of DMP, DBP, BBP, and DEHP in the WWTP was estimated to be 93%, 91%, 90%, and 81%, respectively. Seven to nine percent of the incoming PE were recovered in the WWTP effluent. Factors affecting microbial degradation of DEHP in activated sludge were studied using [U-(14)C-ring] DEHP as tracer. First order rate coefficients for aerobic DEHP degradation were 1.0 x 10(-2), 1.4 x 10(-2), and 1.3 x 10(-3) at 20, 32, and 43 degrees C, respectively. Aerobic degradation rates decreased dramatically under aerobic thermophilic conditions (<0.1 x 10(-2)h(-1) at 60 degrees C). The degradation rate under anoxic denitrifying conditions was 0.3 x 10(-2)h(-1), whereas the rate under alternating conditions (aerobic-anoxic) was 0.8 x 10(-2)h(-1). Aerobic DEHP degradation in activated sludge samples was stimulated 5-9 times by addition of a phthalate degrading bacterium. The phthalate degrading bacterium was isolated from activated sludge, and maintained a capacity for DEHP degradation while growing on vegetable oil. Collectively, the results of the study identified several controls of microbial PE degradation in activated sludge. These controls may be considered to enhance PE degradation in activated sludge WWTP with biological removal of nitrogen and phosphorus.

Infusion of di-2-ethylhexylphthalate for neonates: a review of potential health risk.

Plasticizers leach from polyvinyl chloride medical devices into infusion fluids. One plasticizer frequently found is di-2-ethylhexylphthalate. The Food and Drug Administration estimates that di-2-ethylhexylphthalate exposure exceeding a daily tolerable intake of 0.6 mg/kg per day may harm newborns, especially males. Exposure 20 times the tolerable intake or more may be given daily to certain infants, neonates, and premature infants in the neonatal intensive care unit. Currently, scant data exist on the exact dosage to this population. Furthermore, the exact potential for harm, either subtle or overt, is unknown or disputed. Thus, the recording of exposure history and "dose" in the medical record is warranted.

Effects of dietary di(2-ethylhexyl)phthalate on the metabolism of tryptophan to niacin in mice.

We have reported the effect of di(2-ethylhexyl)phthalate (DEHP) on the tryptophan (Trp)-niacin pathway in rats. To clarify the universal effect of DEHP on rodents, we studied whether DEHP also has an effect on Trp metabolism in mice. Mice were fed a niacin-free, 20% casein diet supplemented with DEHP for 21 days. Feeding with DEHP decreased the body weight gain and increased the liver weight in correlation with the dose level of DEHP. The administration of DEHP significantly increased the formation of quinolinic acid and the lower metabolites of the Trp-niacin pathway. The flux of niacin in the lower part of the Trp-niacin pathway in mice was enhanced by feeding with DEHP.

Identification of a toxic mechanism of the plasticizers, phtahlic acid esters, which are putative endocrine disrupters: time-dependent increase in quinolinic acid and its metabolites in rats fed di(2-ethylhexyl)phthalate.

We have reported that the administration of di(2-ethylhexyl)phthalate (DEHP) increased the formations of quinolinic acid (QA) and its lower metabolites on the tryptophan-niacin pathway. To discover the mechanism involved in disruption of the tryptophan-niacin pathway by DEHP, we assessed the daily urinary excretion of QA and its lower metabolites, and enzyme activities on the tryptophan-niacin pathway. Rats were fed with a niacin-free, 20% casein diet or the same diet supplemented with 0.1% DEHP or 0.043% phthalic acid and 0.067% 2-ethylhexanol added for 21 days. Feeding of DEHP increased the urinary excretions of QA and its lower metabolites in a time-dependent manner, and the increase of these excretions reached a peak at 11 days, but feeding of phthalic acid and 2-ethylhexanol had no effect. Feeding of DEHP, however, did not affect any enzyme activity including alpha-amino-beta-carboxymuconate-epsilon-semialdehyde decarboxylase (ACMSD), affecting the formation of QA, on the tryptophan-niacin pathway.

Selenium metabolism in isolated hepatocytes: inhibition of incorporation in proteins by mono(2-ethylhexyl)phthalate, a metabolite of the peroxisome proliferator di(2-ethylhexyl)phthalate.

Di(2-ethylhexyl)phthalate (DEHP), a rat liver carcinogen, induces peroxisomal proliferation and a concomitant oxidative stress, but decreases liver glutathione peroxidase (GSH-Px) activity. This enzyme is a selenoprotein and we have investigated the influence of mono(2-ethylhexyl)phthalate (MEHP), a major metabolite of DEHP, on selenium incorporation in hepatocellular proteins. [75Se]Selenious acid (6 nM) was added to primary cultures of rat hepatocytes and protein incorporation was assessed by SDS-PAGE and autoradiography. High concentrations of MEHP (1.0-3.0 mM) inhibited selenium labeling of all major selenoproteins in 3-24 h experiments, but also inhibited protein synthesis as assessed by leucine incorporation. The protein synthesis inhibition was reversible. Lower concentrations of MEHP (0.3-0.5 mM) did not decrease the 75Se-labeling in 24 h experiments and did not inhibit leucine incorporation. However, conditions that significantly induced peroxisomal proliferation also affected the 75Se-labeling. Thus in 72 h experiments, 0.05-0.25 mM MEHP increased the labeling of a 58 kd protein, decreased the labeling of a 23 kd protein (with the same mol. wt as GSH-Px), had no effect on a 20 kd protein and decreased the labeling of a 15 kd protein (as compared to MEHP-free control plates). The pattern of changes associated with peroxisomal proliferation mimicked that seen in livers from selenium-deficient animals, as reported by others. These data indicate that the bioavailability of selenium is decreased by DEHP. This effect may relate to a transient inhibition of protein synthesis, but also to the DEHP-induced peroxisomal proliferation.