MEHP induces alteration of mitochondrial function and inhibition of steroid biosynthesis in MA-10 mouse tumor Leydig cells.

Di-(2-ethylhexyl) phthalate (DEHP) is a plasticizer that is widely used in manufacturing. Previous studies have shown that mono-(2-ethylhexyl) phthalate (MEHP), the active metabolite of DEHP, has inhibitory effects on luteinizing hormone (LH)-stimulated steroid biosynthesis by Leydig cells. The molecular mechanisms underlying its effects, however, remain unclear. In the present study, we examined the effects of MEHP on changes in mitochondrial function in relationship to reduced progesterone formation by MA-10 mouse tumor Leydig cells. Treatment of MA-10 cells with MEHP (0-300 µM for 24 h) resulted in dose-dependent inhibition of LH-stimulated progesterone biosynthesis. Biochemical analysis data revealed that the levels of the mature steroidogenic acute regulatory protein (STAR), a protein that works at the outer mitochondrial membrane to facilitate the translocation of cholesterol for steroid formation, was significantly reduced in response to MEHP exposures. MEHP also caused reductions in MA-10 cell mitochondrial membrane potential (ΔΨm) and mitochondrial respiration as evidenced by decreases in the ability of the mitochondria to consume molecular oxygen. Additionally, significant increases in the generation of mitochondrial superoxide were observed. Taken together, these results indicate that MEHP inhibits steroid formation in MA-10 cells at least in part by its effects on mitochondrial function.

A comparative study based on activity, conformation and computational analysis on the inhibition of human salivary aldehyde dehydrogenase by phthalate plasticizers: Implications in assessing the safety of packaged food items.

Phthalate plasticizers are commonly used in various consumer-end products. Human salivary aldehyde dehydrogenase (hsALDH) is a detoxifying enzyme which defends us from the toxic aldehydes. Here, the effect of phthalates [Di-2-ethylhexyl phthalate (DEHP), Diethyl phthalate (DEP) and Dibutyl phthalate (DBP)] on hsALDH has been investigated. These plasticizers inhibited hsALDH, and the IC50 values were 0.48 ± 0.04, 283.20 ± 0.09 and 285.00 ± 0.14 µM for DEHP, DEP and DBP, respectively. DEHP was the most potent inhibitor among the three plasticizers. They exhibited mixed-type linear inhibition with inclination towards competitive-non-competitive inhibition. They induced both tertiary and secondary structural changes in the enzyme. Quenching of intrinsic hsALDH fluorescence in a constant manner was observed with a binding constant (Kb) of 8.91 × 106, 2.80 × 104, and 1.31 × 105 M-1, for DEHP, DEP and DBP, respectively. Computational analysis showed that these plasticizers bind stably in the proximity of hsALDH catalytic site, reciprocating via non-covalent interactions with some of the amino acids which are evolutionary conserved. Therefore, exposure to these plasticizers inhibits hsALDH which increases the risk of aldehyde induced toxicity, adversely affecting oral health. The study has implications in assessing the safety of packaged food items which utilize phthalates.

Prenatal and breastfeeding exposure to low dose of diethylhexyl phthalate induces behavioral deficits and exacerbates oxidative stress in rat hippocampus.

Diethylhexyl phthalate (DEHP) is one of the most important derivatives of phthalate that has devastating effects on nervous system function. In this study, the effects of exposure with low doses of DEHP during pregnancy and lactation periods have been evaluated in rat's puppies. DEHP at doses 5, 40, 400 µg/kg/day and 300 mg/kg/day was given to mothers by gavage during pregnancy and lactation. The spatial and working memories were evaluated by Morris water maze test and Y maze, respectively. Oxidative stress levels were measured by biochemical tests. Histopathology of hippocampal tissue was assessed using hematoxylin and eosin, Nissl staining, and immunohistofluorescence in 60-days-old puppies. Behavioral data showed that low doses of DEHP decreased the working and spatial memories of male rats. Increased oxidative stress and decreased antioxidant activity were also observed in the hippocampus of rats which received the low doses of DEHP. However, neuronal damage, inflammation, and astrocyte activation were not significantly increased in the hippocampus of rats. Overall, exposure of mothers to low doses of DEHP during pregnancy and lactation cause behavioral deficits, especially in male newborn. The destructive effects of low doses of DEHP might be mediated through increased levels of oxidative stress in the brain.

Dose-related morphological changes in the epididymal region of sexually active adult male Japanese quail treated with di-n-butyl phthalate (DBP) commencing during the pre-pubertal stage.

Di-n-butyl phthalate (DBP) is widely used as a plasticizer in personal care and medical products and is known to induce toxicity in the male reproductive organs in both mammals and birds. In this study, there was investigation of the effects of DBP on the epithelium of the rete testis, proximal, and distal efferent ductules and epididymal duct of adult Japanese quail (Coturnix japonica) following treatment with varying doses during the pre-pubertal and peri-pubertal periods. Pre-pubertal quail (n = 25) 4 weeks post-hatching were dosed orally with 10, 50, 200 and 400 mg DBP/kg/d, for 30 days and control birds were administered corn-oil only (n = 5 per group). Histo-metrically, there was lesser (P <  0.001) epithelial heights of the rete testis and efferent ductules in all quail DBP-treated groups, but not in the epididymal duct epithelium. There were no morphological change effects as a result of DBP treatments in the rete testis epithelium, while there were epithelial cytoplasmic vacuoles detected in the distal efferent ductule and epididymal duct of birds treated with 50, 200 and 400 mg DPB/kg/d. There were several lesions, including degenerative changes, cytoplasmic vacuoles, apoptosis and autophagy in the epithelium of the proximal efferent ductule in quail treated with 200 and 400 mg DBP/kg/d. Overall, the results indicate that treatment with DBP during the pre-pubertal period induced dose-dependent histometric and morphological changes in the epithelium of the epididymal region. It is concluded that the proximal efferent ductule was a highly sensitive component of the epididymal tissues of Japanese quail following treatment with DBP during the pre-pubertal period.

Di-(2-ethylhexyl) phthalate-induced tumor growth is regulated by primary cilium formation via the axis of H2O2 production-thymosin beta-4 gene expression.

Di-(2-ethylhexyl) phthalate (DEHP) that is one of the most commonly used phthalates in manufacturing plastic wares regulates tumorigenesis. Thymosin beta-4 (TB4), an actin-sequestering protein, has been reported as a novel regulator to form primary cilia that are antenna-like organelles playing a role in various physiological homeostasis and pathological development including tumorigenesis. Here, we investigated whether DEHP affects tumor growth via primary cilium (PC) formation via the axis of TB4 gene expression and the production of reactive oxygen species (ROS). Tumor growth was increased by DEHP treatment that enhanced TB4 expression, PC formation and ROS production. The number of cells with primary cilia was enhanced time-dependently higher in HeLa cells incubated in the culture medium with 0.1% fetal bovine serum (FBS). The number of cells with primary cilia was decreased by the inhibition of TB4 expression. The incubation of cells with 0.1% FBS enhanced ROS production and the transcriptional activity of TB4 that was reduced by ciliobrevin A (CilioA), the inhibitor of ciliogenesis. ROS production was decreased by catalase treatment but not by mito-TEMPO, which affected to PC formation with the same trend. H2O2 production was reduced by siRNA-based inhibition of TB4 expression. H2O2 also increased the number of ciliated cells, which was reduced by siRNA-TB4 or the co-incubation with CilioA. Tumor cell viability was maintained by ciliogenesis, which was correlated with the changes of intracellular ATP amount rather than a simple mitochondrial enzyme activity. TB4 overexpression enhanced PC formation and DEHP-induced tumor growth. Taken together, data demonstrate that DEHP-induced tumor growth might be controlled by PC formation via TB4-H2O2 axis. Therefore, it suggests that TB4 could be a novel bio-marker to expect the risk of DEHP on tumor growth.

Metabolic, reproductive and thyroid effects of bis(2-ethylhexyl) phthalate (DEHP) orally administered to male and female juvenile rats at dose levels derived from children biomonitoring study.

Bis(2-ethylhexyl) phthalate (DEHP) is a plasticizer used in several items, non-covalently bound to plastics and easily released, since metabolites were found in human matrices. DEHP is an endocrine disrupter and children are particularly vulnerable and susceptible to DEHP effects due to higher exposure levels and developmental stage. A juvenile toxicity study was performed to identify DEHP hazard and mode of action in Sprague-Dawley rats of both sexes during peri-pubertal period - corresponding to childhood phase - from weaning, post-natal day (PND) 23, to full sexual maturity (PND60); the dose levels of 0, 9, 21 and 48 mg/kg bw/day were derived from LIFE PERSUADED biomonitoring study in children. DEHP was administered by gavage for 28 days (5 days/week); timing of preputial separation and vaginal opening was observed during treatment. Histopathological analysis was performed on: adrenals, spleen, liver, thyroid and reproductive organs. The following serum biomarkers were assessed: estradiol, testosterone, anti-Mullerian hormone, tetraiodothyronine, thyroid stimulating hormone, adiponectin and leptin. Gene expression on hypothalamic-pituitary area was focused on follicle stimulating, luteinizing, and thyroid stimulating hormones. The results showed that main targets of DEHP during juvenile period were liver and metabolic system in both sexes, while sex-specific effects were recorded in reproductive system (male rats) and in thyroid (female rats). DEHP exposure during peri-pubertal period at dose levels derived from biomonitoring study in children can induce sex-specific imbalances identifying the juvenile animal model as a sound tool to identify hazards for a reliable risk assessment targeted to children.

Subacute exposure to di-isononyl phthalate alters the morphology, endocrine function, and immune system in the colon of adult female mice.

Di-isononyl phthalate (DiNP), a common plasticizer used in polyvinyl chloride products, exhibits endocrine-disrupting capabilities. It is also toxic to the brain, reproductive system, liver, and kidney. However, little is known about how DiNP impacts the gastrointestinal tract (GIT). It is crucial to understand how DiNP exposure affects the GIT because humans are primarily exposed to DiNP through the GIT. Thus, this study tested the hypothesis that subacute exposure to DiNP dysregulates cellular, endocrine, and immunological aspects in the colon of adult female mice. To test this hypothesis, adult female mice were dosed with vehicle control or DiNP doses ranging from 0.02 to 200 mg/kg for 10-14 days. After the treatment period, mice were euthanized during diestrus, and colon tissue samples were subjected to morphological, biochemical, and hormone assays. DiNP exposure significantly increased histological damage in the colon compared to control. Exposure to DiNP also significantly decreased sICAM-1 levels, increased Tnf expression, decreased a cell cycle regulator (Ccnb1), and increased apoptotic factors (Aifm1 and Bcl2l10) in the colon compared to control. Colon-extracted lipids revealed that DiNP exposure significantly decreased estradiol levels compared to control. Collectively, these data indicate that subacute exposure to DiNP alters colon morphology and physiology in adult female mice.

Comparison of tris(2-ethylhexyl) phosphate and di(2-ethylhexyl) phosphoric acid toxicities in a rat 28-day oral exposure study.

Tris(2-ethylhexyl) phosphate (TEHP, CAS no. 78-42-2) is a plasticizer and a flame retardant, while di(2-ethylhexyl) phosphoric acid (DEHPA, CAS no. 298-07-7) is an oil additive and extraction solvent. Publicly-available information on repeated exposure to these two related organophosphate compounds is fragmentary. Hence, adult male and female Fischer rats were exposed to TEHP (300, 1000 and 3000 mg/kg body weight [BW]/day) or DEHPA (20, 60 and 180 mg/kg BW/day) by gavage for 28 consecutive days, to assess and compare their toxicities. Although significantly impaired BW gains and evidence of TEHP enzymatic hydrolysis to DEHPA were observed only in males, exposures to the highest TEHP and DEHPA doses often resulted in similar alterations of hematology, serum clinical chemistry and liver enzymatic activities in both males and females. The squamous epithelial hyperplasia and hyperkeratosis observed in the non-glandular forestomach of rats exposed to the middle and high DEHPA doses were most likely caused by the slightly corrosive nature of this chemical. Although tubular degeneration and spermatid retention were observed only in the testes of males exposed to the highest TEHP dose, numerous periodic acid-Schiff stained crystalline inclusions were observed in testis interstitial cells at all TEHP dose levels. No-observed-adverse-effect levels for TEHP and DEHPA are proposed, but the lower serum pituitary hormone levels resulting from TEHP and DEHPA exposures and the perturbations of testicular histology observed in TEHP-treated males deserve further investigation. Improved characterization of the toxicity of flame retardants will contribute to better informed substitution choices for legacy flame retardants phased-out over health concerns.

Metabolism and urinary excretion kinetics of di(2-ethylhexyl) adipate (DEHA) in four human volunteers after a single oral dose.

Di(2-ethylhexyl) adipate (DEHA) is used as a substitute for the reprotoxic phthalate plasticizer di(2-ethylhexyl) phthalate (DEHP). This study reports the first quantitative data on human in vivo DEHA metabolism and urinary metabolite excretion with the aim of providing tools for DEHA exposure and risk assessments. After DEHA was administered to four healthy volunteers (107-164 µg/kg body weight (bw)), urine samples were continuously and completely collected for 48 h and analyzed for the specific oxidized monoester metabolites mono-2-ethyl-5-hydroxyhexyl adipate (5OH-MEHA), mono-2-ethyl-5-oxohexyl adipate (5oxo-MEHA), and mono-5-carboxy-2-ethylpentyl adipate (5cx-MEPA), as well as for the non-specific hydrolysis product adipic acid (AA) using stable isotope dilution analysis. AA was confirmed as a major (urinary excretion fraction (FUE): 10-40%), yet non-specific DEHA metabolite. 5cx-MEPA was the major specific DEHA metabolite with an FUE of 0.20% (range: 0.17-0.24%). FUEs for 5OH-MEHA and 5oxo-MEHA were 0.07% (0.03-0.10%) and 0.05% (0.01-0.06%), respectively. The three specific metabolites were excreted with two concentration maxima (tmax1 = 1.5-2.3 h, tmax2 = 3.8-6.4 h). Elimination half-lives (t1/2, calculated after the second tmax) for 5cx-MEPA were calculated between 2.1-3.8 h. The majority (98-100%) of metabolites was excreted within 24 h. The FUE of 5cx-MEPA was applied to demonstrate its applicability for calculating daily intakes based on urinary metabolite levels from three pilot populations. Daily intakes were generally far below the tolerable daily intake (TDI) for DEHA (300 µg/kg bw/day). The highest daily intake (114 µg/kg bw/day) was calculated in individuals after consuming food that had been wrapped in DEHA containing cling film.

Di-(2-ethylhexyl)-phthalate interferes with T-follicular helper cell differentiation and cytokine secretion through signaling lymphocytic activation molecule family member-1.

Exposure to the widely-used phthalate plasticizer di-(2-ethylhexyl)-phthalate (DEHP) has been shown to be closely related to an increased prevalence of allergic diseases in infants and juveniles. Earlier work in our laboratory found that DEHP-related anaphylactic responses could be ascribed to T-follicular helper (Tfh) cell hyperfunction directly. The Tfh cell, a newly identified CD4+ TH cell subset, until recently has been considered as a key player in humoral immunity. Tfh cells can respond to stimulation through various receptors. Signaling lymphocytic activation molecule family member-1 (SLAMF1, CD150) is a surface co-stimulatory receptor that can bind to an intracytoplasmic adaptor signaling lymphocytic activation molecule-associated protein (SAP) to initiate downstream signaling cascades, regulating some events of immune response. The present study explored the role of SLAMF1 in Tfh cell differentiation and cytokine secretion under the condition of DEHP exposure. Using a weanling mice model of DEHP gavage with ovalbumin (OVA) sensitization, it was found that DEHP acted as an immunoadjuvant to elevate SLAMF1 and SAP expression in host Tfh cells. Ex vivo studies of effects from DEHP exposure on Tfh cells from OVA-sensitized hosts showed that DEHP acted in an adjuvant-like manner to promote the expression of adaptor protein SAP, transcription factors Bcl-6 and c-MAF, and cytokines interleukin (IL)-21 and IL-4 in Tfh cells. Transfection of these Tfh cells with Slamf1 small interfering RNA prior to exposure to the DEHP attenuated the over-expression of these molecules that was caused by the DEHP. In conclusion, this study demonstrated that DEHP, via a SLAMF1-mediated pathway, can impact on Tfh cell differentiation and their ability to form select cytokines.

Bioavailability of phthalate and DINCH® plasticizers, after oral administration of dust to piglets.

For decades, phthalates have been widely used as plasticizers in a large number of consumer products, leading to a complex exposure to humans via ingestion, inhalation or dermal uptake. Children may have a higher unintended dust intake per day compared to adults. Therefore, dust intake of children could pose a relevant exposure and subsequently a potential health risk. The aim of this study was to determine the relative bioavailability of certain phthalates, such as di(2-ethylhexyl) phthalate (DEHP), di-isononyl phthalate (DINP) and the non-phthalate plasticizer diisononyl 1,2-cyclohexanedicarboxylic acid (DINCH®, Hexamoll®), after ingestion of dust. Seven 5-week-old male piglets were fed five different dust samples collected from daycare centers. Overall, 0.43 g to 0.83 g of dust sieved to 63 µm were administered orally. The piglets' urine was collected over a period of 38 h. The excreted metabolites were quantified using an LC-MS/MS method. The mean uptake rates of the applied doses for DEHP, DINP, and DINCH® were 43% ± 11%, 47% ± 26%, and 9% ± 3.5%, respectively. The metabolites of DEHP and DINP showed maximum concentrations in urine after three to five hours, whereas the metabolites of DINCH®, reached maximum concentrations 24 h post-dose. The oral bioavailability of the investigated plasticizers was higher compared to the bioaccessibility reported from in vitro digestion tests. Furthermore, the bioavailability of DEHP did not vary substantially between the dust samples, whereas a dose-dependent saturation process for DINP was observed. In addition to other intake pathways, dust could be a source of plasticizers in children using the recent intake rates for dust ingestion.

Hepatic and renal tissue damage in Balb/c mice exposed to diisodecyl phthalate: The role of oxidative stress pathways.

Diisodecyl phthalate (DIDP) is commonly used as a plasticizer in industrial and consumer products, however, its toxicity remains unclear. This study investigated the possible involvement of oxidative stress in DIDP-induced liver and kidney toxicity. Liver function and kidney function, tissue lesions, oxidative stress biomarkers, inflammatory mediators and apoptosis factors were investigated in this study. The results showed that oral exposure to DIDP induced a marked increase in lever of alanine aminotransferase (ALT), aspartate aminotransferase (AST), urinary nitrogen (UREA) and creatinine (CREA), decrease in albumin (ALB) level, as well as causing hepatic and renal histopathological change. Investigation of the role of oxidative stress pathways showed that DBP exposure could lead to a significant increase in levels of reactive oxygen species (ROS), malondialdehyde (MDA), 8-hydroxy-2-deoxyguanosine (8-OHdG), interleukin-1ß (IL-1ß), tumor necrosis factor-α (TNF-α) and nuclear factor-κB (NF-κB), while a decrease in glutathione (GSH) levels were observed. Administration of vitamin E to DIDP-treated mice restored these biochemical parameters to within normal levels, and resulted in less damage to livers and kidneys. Overall, these results suggest that the oxidative stress pathway is involved in DIDP-induced toxicity.

Steady-State Human Pharmacokinetics of Monobutyl Phthalate Predicted by Physiologically Based Pharmacokinetic Modeling Using Single-Dose Data from Humanized-Liver Mice Orally Administered with Dibutyl Phthalate.

Dibutyl phthalate (DBP) was widely used as a plasticizer but it has been recently replaced with other kinds of phthalates such as di(2-ethylhexyl)phthalate and diisononyl phthalate because of its toxicity. To evaluate the human risk of DBP, forward and reverse dosimetry was conducted using in silico simplified physiologically based pharmacokinetic (PBPK) modeling based on in vivo experimental pharmacokinetic data in humanized-liver mice (HL-mice) obtained after an oral dose of 100 mg/kg. Absorbed DBP was converted to monobutyl phthalate (MBP) and its glucuronide extensively in vivo. HL-mice had higher concentrations of MBP glucuronide in plasma than did the control mice. Concentrations of MBP glucuronide in 0-7 h accumulated urine samples from HL-mice were significantly higher than those in control mice. Similarly, in vitro MBP glucuronidation rates mediated by pooled microsomes from rat or mouse livers were lower than those mediated by human liver microsomes. Liver damage by MBP to humanized liver was detected by measuring human albumin mRNA in HL-mouse plasma. By simple PBPK modeling, in silico concentration curves in plasma, liver, or urine following virtual oral administration of DBP were created for rats, control mice, and HL-mice. A human PBPK model for MBP was established based on the HL-mouse PBPK model using allometric scaling without consideration of interspecies factors in terms of liver metabolism. Human PBPK models were used to estimate urinary and plasma concentrations of MBP and its glucuronide throughout 14 days of oral DBP administration (1.2 and 13 µg/kg/day). Reverse dosimetry PBPK modeling found that reported 50th and 95th percentile MBP urine and plasma concentrations of the general population could potentially imply exposures similar to or exceeding tolerable daily intake levels (5-10 µg/kg/day) recommended by the European and Japanese authorities. Further in-depth assessment of DBP is needed to assess the validity of assumptions made based on human biomonitoring data.

Effect of plasticizers on manufacturing ritonavir/copovidone solid dispersions via hot-melt extrusion: Preformulation, physicochemical characterization, and pharmacokinetics in rats.

In this study, novel ritonavir solid dispersion (RTV SD) formulations were prepared with copovidone (PVPVA 64) and optimized plasticizers via hot-melt extrusion (HME) at different extrusion temperature to evaluate the effect of plasticizers on the process of HME. The optimized drug-loading content of RTV SD formulations was around 15% and RTV was converted to the amorphous state and integrated through physical interactions (possibly hydrogen bonding) with the polymeric carrier. Using Span 20 or HSPC as plasticizer, the HME extrusion temperature of RTV SD formulations suggested a decrease of 10 °C or 20 °C. Furthermore, the in vitro release and the in vivo pharmacokinetics analyses both showed that RTV SD formulations using Span 20 or HSPC as plasticizer possessed better release profiles and bioavailability over RTV bulk powder but showed equal physicochemical characteristics compared to RTV SD formulations without plasticizer. According to the increased drug solubility, enhanced dissolution profiles, superior bioavailability, but decreased extrusion temperature in HME process, the RTV SD formulation using HSPC as plasticizer could be potentially applied in the clinic as an efficient drug delivery system, and HSPC is recommended as an efficient plasticizer for manufacturing RTV SD formulations via HME.

Preparation, characterization and evaluation of glycerol plasticized chitosan/PVA blends for burn wounds.

Chitosan like natural polymers have been widely used in burn wound management. Novel low molecular weight chitosan-PVA soft membranes have been studied for antibacterial and wound healing properties. The effectiveness of antibacterial activity was carried against bacterial pathogens while wound healing nature of chitosan was conducted in second degree burns on rabbits as model animal. Rabbits were divided into three groups; control untreated, treated with commercial Fusidic acid (Fu-A) cream and chitosan-PVA membranes. Low molecular weight chitosan showed significant antibacterial property towards bacterial pathogens. Wound healing experiments on second degree burn exhibited chitosan as significant wound healing agent for wound dressings. In morphological studies, normal growth of epidermis was observed and chitosan exhibited more effective for wound healing. Morphological studies also showed that chitosan wound dressings accelerated the granule and fibrous connective tissues formation. Physical characteristics of chitosan-PVA membranes were evaluated by water uptake capacity, SEM analysis, mechanical and water barrier studies.

Assessment of Patient Exposure to Leachables From Lyophilized Drug Formulations Following Reconstitution, Storage, and Administration via Polymeric Packaging/Delivery Systems.

It has been demonstrated that lyophilized drug formulations have an increased propensity to leach substances from the rubber stoppers comprising their primary packaging system when compared to aqueous liquid formulations stored in the same manner. Unfortunately, patient exposure to leachables originating in lyophilized drug products is not known. To that end, the goal of this study was to assess patient exposure to these leachables after reconstitution, storage, and administration of the lyophilized drug. To achieve this goal, several leachables present in 2 commercial lyophilized drug products were quantified after contact with polyvinyl chloride and non-polyvinyl chloride medication bags as well as an infusion set for durations of 15 min to 7 days at refrigerated and ambient temperature. The results obtained from this study showed that the bag's material of construction and the drugs formulation did not impact the mass of the leachables administered. Conversely, the mass of each leachable administered to the patient was reduced or eliminated as the contact duration with the intravenous bag and the temperature increased. However, for shorter contact durations, refrigerated storage, and higher molecular weight compounds, the patient would be exposed to a majority of the leachables originating from the vial.

Single ingestion of di-(2-propylheptyl) phthalate (DPHP) by male volunteers: DPHP in blood and its metabolites in blood and urine.

Di-(2-propylheptyl) phthalate (DPHP) is used as a plasticizer for polyvinyl chloride products. A tolerable daily intake of DPHP of 0.2 mg/kg body weight has been derived from rat data. Because toxicokinetic data of DPHP in humans were not available, it was the aim of the present work to monitor DPHP and selected metabolites in blood and urine of 6 male volunteers over time following ingestion of a single DPHP dose (0.7 mg/kg body weight). Concentration-time courses in blood were obtained up to 24 h for DPHP, mono-(2-propylheptyl) phthalate (MPHP), mono-(2-propyl-6-hydroxyheptyl) phthalate (OH-MPHP), and mono-(2-propyl-6-oxoheptyl) phthalate (oxo-MPHP); amounts excreted in urine were determined up to 46 h for MPHP, OH-MPHP, oxo-MPHP, and mono-(2-propyl-6-carboxyhexyl) phthalate (cx-MPHP). All curves were characterized by an invasion and an elimination phase the kinetic parameters of which were determined together with the areas under the concentration-time curves in blood (AUCs). AUCs were: DPHP > MPHP > oxo-MPHP > OH-MPHP. The amounts excreted in urine were: oxo-MPHP > OH-MPHP> > cx-MPHP > MPHP. The AUCs of MPHP, oxo-MPHP, or OH-MPHP could be estimated well from the cumulative amounts of urinary OH-MPHP or oxo-MPHP excreted within 22 h after DPHP intake. Not considering possible differences in species-sensitivity towards unconjugated DPHP metabolites, it was concluded from a comparison of their AUCs in DPHP-exposed humans with corresponding earlier data in rats that there is no increased risk of adverse effects associated with the internal exposure of unconjugated DPHP metabolites in humans as compared to rats when receiving the same dose of DPHP per kg body weight.

Gestational di-(2-ethylhexyl) phthalate exposure causes fetal intrauterine growth restriction through disturbing placental thyroid hormone receptor signaling.

Previous study reported that gestational Di-(2-ethylhexyl) phthalate (DEHP) exposure caused fetal intrauterine growth restriction (IUGR). We aimed to investigate the role of placental thyroid hormone receptor (THR) signaling in DEHP-induced IUGR. Dams were treated with DEHP (50 or 200 mg/kg) by gavage daily throughout pregnancy. As expected, gestational DEHP exposure dose-dependently caused fetal IUGR. The mRNA levels of placental Thrα1 and Thrß1 were reduced and nuclear translocation of placental THRα1 and THRß1 were suppressed in DEHP-exposed mice even though thyroid hormones in maternal and fetal sera were unaffected. Correspondingly, Vegf, Pgf, Igf1 and Igf2, several THR downstream genes essential for placental angiogenesis, were down-regulated in placenta of DEHP-exposed mice. Histopathology showed that vascular space in the labyrinthine region was shrunken in placenta of DEHP-treated mice. The microvessel density in labyrinthine region was reduced in DEHP-treated mice. A nested case-control study based on MABC suggested that microvessel density was decreased in placenta of SGA cases. Moreover, protein abundance of placental THRα1 and THRß1 were lower in SGA cases. In conclusion, gestational DEHP exposure increases fetal IUGR incidence through disturbing placental THR signaling. The present study, at least partially, elucidate the underlying mechanism of DEHP-induced fetal IUGR.

Impact of the Di(2-Ethylhexyl) Phthalate Administration on Trace Element and Mineral Levels in Relation of Kidney and Liver Damage in Rats.

Di(2-ethylhexyl) phthalate (DEHP) is a widely used synthetic polymer in the industry. DEHP may induce reproductive and developmental toxicity, obesity, carcinogenesis and cause abnormal endocrine function in both human and wildlife. The aim of this study was to investigate trace element and mineral levels in relation of kidney and liver damage in DEHP-administered rats. Therefore, prepubertal male rats were dosed with 0, 100, 200, and 400 mg/kg/day of DEHP. At the end of the experiment, trace element and mineral levels, glucose-6-phosphate dehydrogenase (G6PD), 6-phosphogluconate dehydrogenase (6-PGD), glutathione reductase (GR) and glutathione S-transferase (GST) enzyme activities were evaluated in the serum, liver, and kidney samples of rats. Furthermore, serum clinical biochemistry parameters, organ/body weight ratios and histological changes were investigated to evaluate impact of DEHP more detailed. Our data indicated that sodium (Na), calcium (Ca), potassium (K), lithium (Li), rubidium (Rb) and cesium (Cs) levels significantly decreased, however iron (Fe) and selenium (Se) concentrations significantly increased in DEHP-administered groups compared to the control in the serum samples. On the other hand, upon DEHP administration, selenium concentration, G6PD and GR activities were significantly elevated, however 6-PGD activity significantly decreased compared to the control group in the kidney samples. Decreased G6PD activity was the only significant change between anti-oxidant enzyme activities in the liver samples. Upon DEHP administration, aberrant serum biochemical parameters have arisen and abnormal histological changes were observed in the kidney and liver tissue. In conclusion, DEHP may induce liver and kidney damage, also result abnormalities in the trace element and mineral levels.