Coupled biological and photo-Fenton pretreatment system for the removal of di-(2-ethylhexyl) phthalate (DEHP) from water

The photo-Fenton coupled with a biological system for the removal of di-(2-ethylhexyl) phthalate (DEHP) in wastewater was analyzed. The toxicity of DEHP-containing wastewater was found to be reduced after pretreatment by the photo-Fenton reaction. The effect of different factors, such as DEHP, Fe³⁺ and H₂O₂ concentrations and the reaction time, on degradation efficiency was investigated. The optimal time to stop the pretreatment process and introduce the effluent to the biological system was 60 min. The results show that effluent of DEHP-containing wastewater pretreated by the photo-Fenton method is biodegradable and that mineralization can be completed when the wastewater is subsequently treated in a biological system. The coupled Fenton and biological treatment system for the degradation of DEHP-containing wastewater can be successfully performed in a semi-continuous mode. These results indicate that the coupled photo-biological system is an effective and potential method for the treatment of DEHP-containing wastewater.     

Biochemical alterations in rat fetal liver following in utero exposure to di(2-ethylhexyl)phthalate (DEHP)

Oral administration of DEHP, 1000 mg/kg body weight, to rats daily from 6 to 15 day of gestation resulted in retardation of fetal growth and increase in fetal liver weight which contained significant quantities of DEHP. The activities of mitochondrial succinate dehydrogenase, malate dehydrogenase, cytochrome c oxidase and adenosine triphosphatase were decreased in fetal liver. The data indicate that exposure of mothers to DEHP during pregnancy could adversely affect the fetal livers by interfering with bioenergetics of the cell.     

Effects of early pubertal exposure to di-(2-ethylhexyl) phthalate on social behavior of mice

Di-(2-ethylhexyl) phthalate (DEHP), a main member of phthalates used as plasticizer in PVC plastics, is an environmental endocrine disrupter. The present study investigated the effect of DEHP on social behavior of mice following pubertal exposure (1, 10, 50, and 200 mg/kg/d) from postnatal day 28 through postnatal day 42. The results showed that, in pubertal females, DEHP reduced the time spent in social play and social investigation and inhibited sociability, but a contrary effect was found in pubertal males, suggesting that the effect of DEHP on pubertal social behavior displays sex differences. In adults, DEHP reduced sociability in females and inhibited social play and social investigation in males, suggesting that early pubertal exposure to DEHP not only plays a significant role in puberty but also alters social behavior in adults. In addition, the present study showed that the higher dose of DEHP (50, 200 mg/kg/d) reduced the relative weight of bilateral testis and anogenital distance of pubertal or adult males, suggesting an anti-androgenic activity of DEHP. These results suggest that early pubertal exposure to DEHP sex- and age- specifically affected the social behaviors of pubertal and even adult mice.     

Expression of catalase and glutathione S-transferase genes in Chironomus riparius on exposure to cadmium and nonylphenol

Antioxidant enzymes play important roles in the protection against oxidative damage caused by environmental pollutants by scavenging high levels of reactive oxygen species and have been quantified as oxidative stress markers. However, combining mRNA expressions of genes coding for detoxification enzymes along with enzyme activities will be more useful biomarkers of stress. Therefore, in this study the cDNA of the catalase gene from the aquatic midge, Chironomus riparius (CrCAT) was sequenced using 454 pyrosequencing. The 2139 bp CrCAT cDNA included an open reading frame of 1503 bp encoding a putative protein of 500 amino acids with a predicted molecular mass of 56.72 kDa. There was an 18 bp 5’ and a long 618 bp 3' untranslated region with a polyadenylation signal site (AATAAA). The deduced amino acid sequence of CrCAT contained several highly conserved motifs including the proximal heme–ligand signature sequence RLFSYNDTX and the proximal active site signature FXRERIPERVVHAKGXGA. A comparative analysis showed the presence of conserved amino acid residues and all of the catalytic amino acids (His⁷⁰, Asn¹⁴³, and Tyr³⁵³) were conserved in all species. The CrCAT contained three potential glycosylation sites and a peroxisome targeting signal of ‘AKM’. The mRNA was detected using RT-PCR at all developmental stages. The time-course expression of CrCAT was measured using quantitative real-time PCR after exposure to different concentration and durations of Paraquat (PQ), cadmium chloride (Cd) and nonylphenol (NP). The expression of CrCAT was significantly up regulated on exposure to 50 and 100 mg/L PQ for 12 and 24 h. Among the different concentrations and durations of Cd tested, significantly highest level of expression for CrCAT mRNA and catalase enzyme activity was observed on exposure to 10 mg/L for 24 h. In the case of NP, the highest level of CrCAT expression was observed after exposure to 100 μg/L for 24 h. The expression profiles of three selected C. riparius glutathione S-transferase genes (CrGSTs) viz. CrGSTdelta3, CrGSTsigma4 and CrGSTepsilon1 was also studied on exposure to NP and were up or down regulated at different time points and concentrations. Significantly highest level of expression for CrGSTdelta3 was observed after 48 h and for CrGSTsigma4 and CrGSTepsilon1 after 24 h exposure to 100 μg/L of NP. The results show that CrGSTs and CrCAT could be used as potential biomarkers in C. riparius for aquatic ecotoxicological studies.     

Biological monitoring of the five major metabolites of di-(2-ethylhexyl)phthalate (DEHP) in human urine using column-switching liquid chromatography-tandem mass spectrometry

We present a fast and reliable on-line clean-up HPLC-method for the simultaneous determination of the five major urinary metabolites of di-(2-ethylhexyl)phthalate (DEHP) namely mono-(2-ethyl-5-carboxypentyl)phthalate (5carboxy-MEPP), mono-[2-(carboxymethyl)hexyl]phthalate (2carboxy-MMHP), mono-(2-ethyl-5-hydroxyhexyl)phthalate (5OH-MEHP), mono-(2-ethyl-5-oxohexyl)phthalate (5oxo-MEHP) and mono-(2-ethylhexyl)phthalate (MEHP). These metabolites represent about 70% of an oral DEHP dose. We for the first time succeeded to reliably quantify 5carboxy-MEPP and to identify 2carboxy-MMHP as major metabolites in native urines of the general population. The analytical procedure consists of an enzymatic hydrolysis, on-line extraction of the analytes from urinary matrix by a restricted access material column (RAM), back-flush transfer onto the analytical column (betasil phenylhexyl), detection by ESI-tandem mass spectrometry and quantification by isotope dilution (limit of detection (LOD) 0.25 microg/l). Median concentrations of a small collective taken from the general population (n=19) were 85.5 microg/l (5carboxy-MEPP), 47.5 microg/l (5OH-MEHP), 39.7 microg/l (5oxo-MEHP), 9.8 microg/l (MEHP) and about 37 microg/l (2carboxy-MMHP). The presented method can provide insights into the actual internal burden of the general population and certain risk groups. It will help to further explore the human metabolism of DEHP-an occupational and environmental toxicant of great concern.     

Polar metabolites of di-(2-ethylhexyl)phthalate in the rat

Di-(2-ethylhexyl)phthalate (DEHP) is an important industrial chemical widely used as a plasticizer for vinyl and other plastics. DEHP is extensively metabolized by mammals, different species showing dramatic differences in metabolite distributions. Previous studies of the metabolism in rats led to the suggestion that the enzymatic processes normally associated with omega-, omega-1, alpha-, and beta-oxidation of fatty acids could account for the known metabolites of DEHP found in the urine. Several additional metabolites of DEHP have been identified in the present study. Their formation requires that the initial hydroxylation process be less specific than fatty acid omega- and omega-1 oxidation are thought to be. Furthermore, it is necessary to postulate either that the aliphatic chain of mono-(2-ethylhexyl)phthalate can be oxidized at two sites simultaneously, or that oxidation products can be recycled for a second hydroxylation prior to excretion.     

DEHP对中国林蛙精巢中StAR、CYP17和CYP19基因表达的影响

为探讨邻苯二甲酸二(2-乙基己基)酯(di-2-ethylhexyl phthalate,DEHP)对两栖动物精巢类固醇激素合成的影响,将中国林蛙(Rana chensinensis)雄性成体分别暴露于浓度为10-7、10-6、10-5、10-4mol·L-1DEHP的水体,分别在暴露20、30和40d取其精巢,提取精巢总RNA,逆转录合成cDNA,通过荧光实时定量PCR检测StAR、CYP17和CYP19mRNA表达相对值。结果表明:与对照组相比,DEHP处理组StAR和CYP19基因表达均上调,CYP17基因表达下调;比较不同DEHP浓度和不同暴露时间对StAR、CYP17和CYP19mRNA表达相对值的影响,显示DEHP浓度变化对3个基因表达影响的规律性不强,而DEHP暴露时间的累积效应较明显;提示DEHP可通过干扰中国林蛙精巢中StAR、CYP17和CYP19基因表达,影响其相应关键酶的表达,从而干扰类固醇激素的合成,产生雌激素效应。     

In utero exposure to the antiandrogen di-(2-ethylhexyl) phthalate decreases adrenal aldosterone production in the adult rat

We previously reported that in utero exposure of the male fetus to the plasticizer di-(2-ethylhexyl) phthalate (DEHP) resulted in decreased circulating levels of testosterone in the adult without affecting Leydig cell numbers, luteinizing hormone levels, or steroidogenic enzyme expression. Fetal exposure to DEHP resulted in reduced mineralocorticoid receptor (MR; NR3C2) expression in adult Leydig cells. In the present studies, treatment of pregnant Sprague-Dawley dams from Gestational Day 14 until birth with 20, 50, 100, 300, or 750 mg kg(-1) day(-1) of DEHP resulted in significant sex-specific decreases in serum aldosterone but not corticosterone levels at Postnatal Day 60 (PND60) but not at PND21. There was no effect on circulating levels of potassium, angiotensin II or adrenocorticotropin hormone (ACTH). However, there was reduced expression of AT receptor Agtr1a, Agtr1b, and Agtr2 mRNAs. The mRNA levels of proteins and enzymes implicated in aldosterone biosynthesis were not affected by in utero DEHP treatment except for Cyp11b2, which was decreased at high (≥ 500 mg kg(-1) day(-1)) doses. The data presented herein, together with our previous observation that aldosterone stimulates testosterone production via an MR-mediated mechanism, suggest that in utero exposure to DEHP causes reduction in both adrenal aldosterone synthesis and MR expression in Leydig cells, leading to reduced testosterone production in the adult. Moreover, these results suggest the existence of a DEHP-sensitive adrenal-testis axis regulating androgen formation.     

Compartmentation of the plant metabolic enzymes for the persistent plasticizer chemical,bis-2(-ethylhexyl)-phthalate

The environmentally persistent plasticizer chemical, bis-(2-ethylhexyl)-phthalate (DEHP), was not translocated or metabolized over 17 days after application to intact wheat leaves. The chemical was specifically associated with the cuticle fraction. In contrast, metabolism was observed in injured leaves and in leaf homogenates.DEHP esterase was 10-fold purified from the wheat leaf homogenate, and an apparent molecular weight of 38 000 was determined by gel permeation chromatography.Cleavage of DEHP by the partially purified esterase was strongly inhibited by a wheat cell wall and by a triglyceride preparation. Cleavage of the water-soluble substrate, 4-nitrophenylacetate, was not inhibited under the same conditions.Compartmentation of metabolic enzymes is proposed as an explanation for the persistence of DEHP and certain other environmental chemicals in plants.     

Biochemical effects of di-2-ethylhexyl phthalate.

Di-2-ethylhexyl phthalate (DEHP) is a widely used plasticizer in the plastics industry. Biochemical changes in rat blood and liver were studied at 21 days after 3 intraperitoneal injections of DEHP on days 1, 5 and 10. In the liver, a decrease in the activity of succinic dehyrogenase (SDH) and adenosine triphosphate and an increase in alkaline phosphatase activity was observed. In serum the activity of acid and alkaline phosphatases and glutamic oxaloacetic and glutamic pyruvic transaminases remained unaltered. Under in vitro conditions, only the activity of SDH was inhibited when homogenates or mitochondrial preparations from normal rat liver were incubated with DEHP and the degree of inhibition was related to the concentration of the plasticizer.     

Toxicokinetics of di(2-ethylhexyl) phthalate (DEHP) and its effects on luteal function in sheep

The aim of the present study was to determine the toxicokinetics of short-term exposures to di(2-ethylhexyl) phthalate (DEHP) and its effects on ovarian cyclicity and luteal function using a sheep experimental model. For establishing the model, we examined the clearance of DEHP after intravenous (i.v.) and intramuscular (i.m.) administration of a single dose of 25 mg/kg body weight (b.w.) and after i.m. administration of two different doses (25 and 50 mg/kg b.w.; DEHP25 and DEHP50, respectively) three times a week for two months. Results showed a significant, dose-dependent effect of DEHP administration, when compared to the control group (CTL; untreated ewes; n = 6), on the duration of the ewes’ estrous cycles (17.1 ± 0.5 days, CTL; 15.1 ± 0.9 days, DEHP25; 12.0 ± 0.8 days, DEHP50; p < 0.05); 94.9% of the cycles were of regular duration (15–19 days) in CTL, but only 51.1% and 25.4% in DEHP25 and DEHP50, respectively. Corpora lutea (CL) were smaller in DEHP50 than in DEHP25 (p < 0.05) and were smaller in both groups than in CTL (p < 0.005), but the maximum plasma concentrations of progesterone were greater (p < 0.05) in DEHP25 and DEHP50 than in CTL. In conclusion, the exposure of cycling ewes to DEHP causes shortening of the ovulatory cycles due mainly to a reduction in the size and lifespan of CL. However, the exposure to the phthalate is also associated with an increase in circulating concentrations of progesterone, suggesting the influence of DEHP on steroid metabolism.     

邻苯二甲酸酯在不同品种通菜-土壤系统中的累积效应研究

在邻苯二甲酸(2-乙基己基)酯(DEHP)不同污染程度的水稻土上盆栽不同品种通菜,应用GC／MS联机检测技术研究了通菜-土壤系统中DEHP的环境行为与归宿．结果表明,通菜中DEHP的含量为0．335～12．710mg·kg^-1,与土壤的污染程度呈正相关．不同品种通菜之间对DEHP的吸收累积效应存在显著差异,与其叶子大小存在一定的正相关关系．种植不同品种通菜后土壤中DEHP的残留量(1．424～19．834mg·kg^-1)存在显著差异．通菜对土壤中DEHP的BCFs都小于1．0,与土壤的污染程度呈负相关．不同通菜品种的BCFs之间存在显著差异,中等叶子通菜品种的BCFs相对较大。     

Non-mutagenicity of 4 metabolites of di(2-ethylhexyl)phthalate (DEHP) and 3 structurally related derivatives of di(2-ethylhexyl)adipate (DEHA) in the Salmonella mutagenicity assay

Four metabolites of the rat liver carcinogen di(2-ethylhexyl)phthalate (DEHP) (mono-(2-ethylhexyl)phthalate, mono-(2-ethyl-5-hydroxyhexyl)phthalate, mono-(2-ethyl-5-oxohexyl)phthalate, and mono-(5-carboxy-2-ethylpentyl)phthalate) and 3 structurally related derivatives of di(2-ethylhexyl)adipate (DEHA) (mono-(2-ethylhexyl)adipate, mono-(2-ethyl-5-hydroxyhexyl)adipate, and mono-(2-ethyl-5-oxohexyl)adipate) were tested for mutagenicity in the Ames assay using Salmonella typhimurium strains TA97, TA98, TA100, and TA102, with and without a metabolic activation preparation. Aroclor 1254-induced rat liver S9 and DEHP-induced rat liver S9 were used. Concentrations of these compounds up to 1000 micrograms/plate were negative with all tester strains in the presence or absence of metabolic activation.     

Development and localization of microsatellite markers for the sibling species Chironomus riparius and Chironomus piger (Diptera: Chironomidae)

Five variable microsatellite loci are reported for the nonbiting midge species Chironomus riparius and Chironomus piger. All loci show considerable intraspecific variation and species‐specific alleles, which allow to discriminate among the two closely related species and their interspecific hybrids, and to estimate genetic diversity within and between populations. Additionally, the loci were localized on C. riparius polytene chromosomes to verify their single copy status and investigate possible chromosomal linkage. The described markers are used in different studies with regard to population and ecological genetics and evolutionary ecotoxicology of Chironomus.     

Effects of uterine and lactational exposure to di-(2-ethylhexyl) phthalate on spatial memory and NMDA receptor of hippocampus in mice

Di-(2-ethylhexyl) phthalate (DEHP) is an environmental endocrine disrupter. Currently, little is known about neurodevelopmental toxicity of DEHP in wildlife and humans. The present study investigated the effects of DEHP, focusing on the changes in the behavior of offspring mice at the ages of 6 and 12 w, respectively, following utero and lactational exposure to DEHP (10, 50, and 200 mg/kg/d) from gestation day 7 through postnatal day 21. The results of open field tasks showed that DEHP increased the grooming of males at age 6 w and females at age 12 w but decreased the frequency of rearing of 6-w-old females and the number of grid crossings of 12-w-old females. In the Morris water maze task, 50 and 200 mg/kg/d DEHP significantly prolonged the time of searching the hidden platform in water maze and reduced the time staying in the target quadrant during a probe trial of 6-w-old male mice, but not of 6-w-old females nor 12-w-old mice of both sexes, suggesting an impaired spatial learning and memory among younger males after perinatal exposure to DEHP. Western blot analyses further showed that DEHP at 50 and 200 mg/kg/d decreased the levels of the N-methyl-d-aspartic acid (NMDA) receptor subunits NR1 and NR2B in the hippocampus of 6-w-old males. These results suggest that uterine and lactational exposure to low doses of DEHP sex-specifically impacted behaviors, including locomotion activity and spatial memory, via the concomitant inhibition of the NMDA receptor of the hippocampus in offspring mice.     

邻苯二甲酸二乙基己酯对翡翠贻贝(Perna viridis)生化指标的影响

实验条件下,研究邻苯二甲酸二乙基己酯(DEHP)5个浓度组(0、0.38、1.92、9.60和48.00mg.L-1)长时间胁迫下翡翠贻贝(Perna viridis)内脏团和外套膜中抗氧化酶(SOD和CAT)活性和丙二醛(MDA)含量的变化,以及胁迫解除后这些指标的恢复情况。结果表明:在胁迫过程中,翡翠贻贝内脏团SOD活性表现为先显著升高,随后受抑制而逐渐降低(P<0.05),CAT活性则表现为先被抑制后受诱导,15d后恢复到对照组水平,MDA含量呈显著增加的趋势(P<0.05);外套膜中的SOD活性在胁迫初期在低浓度组被抑制,而在高浓度组则被诱导(P<0.05),4d后SOD活性逐渐恢复到对照组水平,各浓度组MDA含量均出现明显的增加(P<0.05);净化阶段,低浓度组(0.38mg.L-1)内脏团SOD活性和CAT活性逐渐恢复到对照组水平,但MDA含量升高;净化7d后,除高浓度组(48.00mg.L-1)外,其余浓度组外套膜中SOD活性均已经恢复到对照组水平,MDA含量也没有出现明显升高的现象。研究表明,DEHP对翡翠贻贝内脏团和外套膜抗氧化防御系统酶具有明显的影响,DEHP诱导引起2种组织内脂质过氧化损伤,并且短期内这种损伤无法消除。