Di-(2-ethylhexyl) Phthalate Exposure Research Articles

EFFECT OF DI-(2-ETHYLHEXYL) PHTHALATE (DEHP) EXPOSURE ON MICROARCHITECTURE OF FEMORAL BONE IN MALE LABORATORY MOUSE: PRELIMINARY RESULTS

Di-2-ethylhexyl phthalate (DEHP) is a toxic and hazardous endocrine disruptor with adverse effects on animal and human health. However, its impact on bone tissue has not been sufficiently investigated. Therefore, the purpose of our preliminary study was to examine the effects of DEHP on compact bone structure in two 57-days-old male mice. Daily oral administration of DEHP (4.5 mg/kg body weight dissolved in 500 µl of peanut oil per 15 days) was studied, compared to a control. We observed a significant effect of DEHP exposure on macroscopic bone characteristics. Similarly, we identified differences in qualitative characteristics, such as the presence of resorption lacunae and absence of non-vascular and primary vascular radial bone tissue near the endosteal border, compared to the control. On the contrary, quantitative analysis showed no demonstrable alterations in morphometric parameters. Our preliminary findings support the hypothesis about the negative impact of DEHP on bone tissue. However, further investigation is needed to understand this issue better and more precisely.

Long-term chronic exposure to di-(2-ethylhexyl)-phthalate induces obesity via disruption of host lipid metabolism and gut microbiota in mice

BackgroundNumerous epidemiological findings have shown that di-(2-ethylhexyl)-phthalate (DEHP), one of industrial plasticizers with endocrine-disrupting properties, positively contributes to high incidence of obesity. However, potential pathogenesis of dietary DEHP exposure-induced obesity remains largely unknown. MethodsChronic DEHP exposure at different doses (0.05 and 5 mg/kg body weight) to mice had been continuously lasted for 14 weeks through the diet. A combination of targeted quantitative metabolomics (LC/GC-MS) with global 1H NMR-based metabolic profiling to explore the effects of dietary DEHP exposure with different doses on host lipid metabolism of mice. Metagenomics (16S rRNA gene sequencing) was also employed to examine the alterations of gut microbiota composition in the cecal contents of mice after dietary DEHP exposure. ResultsDietary exposure to DEHP at both doses induced weight gain and hepatic lipogenesis of mice by promoting the uptake of fatty acids and disrupting phospholipids and choline metabolism. Dietary DEHP exposure altered the gut microbiota community with disruption of intestinal morphology and reduction of Firmicutes to Bacteroidetes ratio in the cecal contents of mice. Furthermore, DEHP exposure activated gut microbiota fermentation process producing excess short chain fatty acids of mice. ConclusionThese findings provide systematic evidence that long-term chronic DEHP exposure induces obesity through disruption of host lipid metabolism and gut microbiota in mice, which not only confirm the epidemiological results, but also expand our understanding of metabolic diseases caused by environmental pollutants exposure.

Effects of Prenatal Phthalate Exposure and Childhood Exercise on Maternal Behaviors in Female Rats at Postpartum: A Role of Oxtr Methylation in the Hypothalamus.

Both the detrimental effect of prenatal exposure to di-(2-ethylhexyl)-phthalate (DEHP) and the beneficial effects of physical exercise on brain functions have been reported. The oxytocin pathway has been implicated in the onset of maternal behaviors. Epigenetic modification of the oxytocin receptor gene (OXTR) through DNA methylation has been associated with the pathogenesis of neuropsychiatric disorders. The purpose of this study was to investigate the effects of prenatal DEHP exposure on oxytocin-regulated maternal behaviors and to examine the protective effect of exercise. Pregnant rats (F0) were fed with vehicle or DEHP during gestation and the offspring females (F1) were assessed for their maternal behaviors by pup retrieval test at postpartum. The results showed that reduced pup retrieval activities without significant alteration of stress responses were observed in the prenatally DEHP-exposed females. Prenatal DEHP exposure decreased the expressions of oxytocin, Oxtr mRNA, and oxytocin receptor, and increased Oxtr methylation in the hypothalamus of postpartum female rats. There were no significant effects of exercise on behavioral, biochemical, and epigenetic measurements. These results suggest that prenatal DEHP exposure has a long-term adverse effect on maternal behaviors; Oxtr hyper-methylation may be a potential epigenetic mechanism for this alteration, which cannot be prevented by physical exercise during childhood.

Subacute Exposure to an Environmentally Relevant Dose of Di-(2-ethylhexyl) Phthalate during Gestation Alters the Cecal Microbiome, but Not Pregnancy Outcomes in Mice

Di-2-ethylhexyl phthalate (DEHP) is a plasticizer commonly found in polyvinyl chloride, medical equipment, and food packaging. DEHP has been shown to target the reproductive system and alter the gut microbiome in humans and experimental animals. However, very little is known about the impact of DEHP-induced microbiome changes and its effects during pregnancy. Thus, the objective of this study was to investigate the effects of DEHP exposure during pregnancy on the cecal microbiome and pregnancy outcomes. Specifically, this study tested the hypothesis that subacute exposure to DEHP during pregnancy alters the cecal microbiome in pregnant mice, leading to changes in birth outcomes. To test this hypothesis, pregnant dams were orally exposed to corn oil vehicle or 20 µg/kg/day DEHP for 10 days and euthanized 21 days after their last dose. Cecal contents were collected for 16S Illumina and shotgun metagenomic sequencing. Fertility studies were also conducted to examine whether DEHP exposure impacted birth outcomes. Subacute exposure to environmentally relevant doses of DEHP in pregnant dams significantly increased alpha diversity and significantly altered beta diversity. Furthermore, DEHP exposure during pregnancy significantly increased the relative abundance of Bacteroidetes and decreased the relative abundance of Firmicutes and Deferribacteres compared with controls. The affected taxonomic families included Deferribacteraceae, Lachnospiraceae, and Mucisprillum. In addition to changes in the gut microbiota, DEHP exposure significantly altered 14 functional pathways compared with the control. Finally, DEHP exposure did not significantly impact the fertility and birth outcomes compared with the control. Collectively, these data indicate that DEHP exposure during pregnancy shifts the cecal microbiome, but the shifts do not impact fertility and birth outcomes.

Geographic distribution and time trend of human exposure of Di(2-ethylhexyl) phthalate among different age groups based on global biomonitoring data

Despite being restricted by many authorities, di (2-ethylhexyl) phthalate (DEHP) is still widely detected in the environment and biospecimens. To indentify populations of high risk and evaluate the effects of DEHP restrictions, we elucidated the geographic distribution of DEHP exposure levels among pregnant women and different age groups, and compared the time trend of exposure levels with the time course of productions/restrictions. The estimated daily intake (EDI) was calculated based on biomonitoring data in published epidemiological studies, and then the group EDI (EDIG) was calculated for one particular population, region, or period by weighting EDIs by sample sizes. Overall, 144,965 samples from 45 nations were included, with the sampling time ranging from 1982 to 2017. Children had the highest exposure level (5.50 μg/kg bw/day) worldwide, while infants and pregnant women had low levels (2.13 and 1.89 μg/kg bw/day, respectively). The EDIGs varied considerably between countries, and the majority of corresponding hazard quotients were less than 1; however, the risk behind can not be ignored. In the general population, the DEHP exposure level showed a downtrend from 4.40 μg/kg bw/day before 2000 to 2.23 μg/kg bw/day in 2015–2017. In the European Union, the annual trend of DEHP EDIGs of children and adults fitted the production and consumption volume, and the EDIGs decreased more sharply in children. The EDIGs of children decreased with a delay along with the regulations on the use of DEHP. Cutting productions/consumptions and restrictions are effective to reduce DEHP exposure, but current efforts are far from enough on a worldwide scale.

Review on Toxic Effects of Di(2-ethylhexyl) Phthalate on Zebrafish Embryos

Di(2-ethylhexyl) phthalate (DEHP) is widely used as a plasticizer in consumer products. People are continuously exposed to DEHP through ingestion, inhalation and dermal absorption. From epidemiological studies, DEHP has been shown to associate with various adverse health effects, such as reproductive abnormalities and metabolic diseases. Health concerns have been raised regarding DEHP exposures; therefore, relevant risk assessment has become necessary through toxicological testing of DEHP. In the past 10 years, an increasing number of DEHP toxicity studies have been using zebrafish embryos as an in vivo model due to their high fecundity, rapid embryonic development as well as optical transparency, which have now been established as an alternative of the more conventional rodent model. The aim of the present paper is to review the effects of acute (from embryo stage to 1 week) and chronic (from embryo stage to 1 week) DEHP exposures on zebrafish, which start from the embryonic stage, and to analyze acute and potential long-term effects induced by acute exposure and effects induced by chronic exposure of DEHP upon subjecting to exposures, starting from the embryonic stage to different developmental stages, with a view to facilitate risk assessments on DEHP exposures.

Maternal high-fat diet during pregnancy with concurrent phthalate exposure leads\xa0to abnormal placentation

Di(2-ethylhexyl) phthalate (DEHP) is a synthetic chemical commonly used for its plasticizing capabilities. Because of the extensive production and use of DEHP, humans are exposed to this chemical daily. Diet is a significant exposure pathway and fatty food contain the highest level of phthalates. The impact on pregnancy following DEHP exposure and the associated interaction of high fat (HF) diet remains unknown. Here we report that exposure of pregnant mice to an environmentally relevant level of DEHP did not affect pregnancy. In contrast, mice fed a HF diet during gestation and exposed to the same level of DEHP display marked impairment in placental development, resulting in poor pregnancy outcomes. Our study further reveals that DEHP exposure combined with a HF diet interfere with the signaling pathway controlled by nuclear receptor PPARγ to adversely affect differentiation of trophoblast cells, leading to compromised vascularization and glucose transport in the placenta. Collectively, these findings demonstrate that maternal diet during pregnancy is a critical factor that determines whether exposure to an environmental toxicant results in impaired placental and fetal development, causing intrauterine growth restriction, fetal morbidity, and mortality.

Transcriptome and in silico approaches provide new insights into the mechanism of male reproductive toxicity induced by chronic exposure to DEHP

Di-(2-ethylhexyl) phthalate (DEHP) can affect the male reproductive system in vertebrates, but the underlying molecular mechanism is still elusive. Therefore, in this study, we aimed to dig the in-depth mechanism of DEHP-induced reproductive toxicity on male zebrafish via testicular transcriptome using embryo exposed at the environmentally relevant concentration (ERC) of 100 μg/L for 111 days. Moreover, our results were further confirmed via in silico technique and bioassay experimental in vitro (cell lines) and in vivo (zebrafish). The results showed DEHP exposure could affect male spermatogenesis, altered gonad histology, and reduced egg fertilization rate. Transcriptome analysis identified 1879 significant differentially expressed genes enriched in the exposure group. Twenty-seven genes related to three pathways of reproduction behavior were further validated by qPCR. In silico molecular docking revealed that DEHP and its metabolism bind to the zebrafish progesterone receptor (Pgr), suggesting the potential disruption of DEHP to the normal Pgr signaling. To further validate it, a wild-type Pgr plasmid and its mutants on specific binding sites were constructed. The transfection and microinjection experiment demonstrated that these binding sites mutations of Pgr affected the expression levels of male reproductive toxicity. Taken together, our study provided new insight into the molecular mechanisms of male reproductive toxicity induced by DEHP, and Pgr may serve as an important target binding by DEHP pollution, which needs further study in the future.

Di (2-ethyl-hexyl) phthalate disrupts placental growth in a dual blocking mode

Di (2-ethyl-hexyl) phthalate (DEHP) is a widely used plasticizer. Maternal DEHP exposure inhibits cell proliferation and reduces placentas size, which associates with fetal growth restriction and adulthood diseases. However, the mechanism of placental cell proliferation inhibition by DEHP remains elusive. This study investigated the effect of DEHP on placental cell proliferation from cell cycle arrest. Utilizing in vitro and in vivo experiments, we investigated cell cycle arrest, DNA double-strand break (DSB) repair, genotoxic stress response, and micronuclei formation. Most DEHP metabolizes to mono (2-Ethylhexyl) phthalate (MEHP) and distributes to organs quickly, so MEHP and DEHP were used in cultured cell and animal experiments, respectively. Here, a double blocking mode for the proliferation inhibition of the placental cell was revealed. One is that the classical DSB repair pathways were suppressed, which arrested the cell cycle at the G2/M phase. The other is that DEHP stimulated an elevated level of progesterone, which blocked the cell cycle at metaphase by disrupting chromosome arrangement. These two sets of events facilitated micronuclei formation and resulted in cell proliferation inhibition. This findings provide a novel mechanistic understanding for DEHP to inhibit placental cell proliferation.

Epi-mutations for spermatogenic defects by maternal exposure to di(2-ethylhexyl) phthalate.

Exposure to environmental factors during fetal development may lead to epigenomic modifications in fetal germ cells, altering gene expression and promoting diseases in successive generations. In mouse, maternal exposure to di(2-ethylhexyl) phthalate (DEHP) is known to induce defects in spermatogenesis in successive generations, but the mechanism(s) of impaired spermatogenesis are unclear. Here, we showed that maternal DEHP exposure results in DNA hypermethylation of promoters of spermatogenesis-related genes in fetal testicular germ cells in F1 mice, and hypermethylation of Hist1h2ba, Sycp1, and Taf7l, which are crucial for spermatogenesis, persisted from fetal testicular cells to adult spermatogonia, resulting in the downregulation of expression of these genes. Forced methylation of these gene promoters silenced expression of these loci in a reporter assay. These results suggested that maternal DEHP exposure-induced hypermethylation of Hist1h2ba, Sycp1, and Taf7l results in downregulation of these genes in spermatogonia and subsequent defects in spermatogenesis, at least in the F1 generation.

Effects of Di-2-ethylhexyl phthalate on growth, lipid peroxidation and antioxidative enzyme activity in Dunaliella salina

Di-2-ethylhexyl phthalate (DEHP) is a toxic organic compound. It has been shown to exert negative effects on non-targeted aquatic organisms. In order to study the toxicological effects of DEHP on marine microalgae, we investigated cell growth, oxidative damage and antioxidant enzyme activities of Dunaliella salina under DEHP treatment. After exposure to DEHP of 10 to 800 mg/L for 7 days, D. salina growth was gradually inhibited with the increase in DEHP concentration. After D. salina was exposed to 400 mg/L DEHP for 4 days, the contents of malondialdehyde and hydrogen peroxide in D. salina were significantly increased as compared with those in the control group. After 6 days of exposure to DEHP at 10 to 400 mg/L, glutathione peroxidase activity in D. salina was significantly reduced in the 10 and 40 mg/L DEHP groups. Exposure of D. salina to 100 to 400 mg/L DEHP resulted in significantly higher inhibition of total superoxide dismutase in D. salina (p<0.05), and copper-zinc superoxide dismutase of D. salina was significantly inhibited compared with that of the control group (p<0.01). The results showed that DEHP exposure can damage the antioxidant defense system and cause cell death in D. salina.

English

Lead and di-(2-ethylhexyl) phthalate (DEHP) are common environmental toxicants of concern around the world. Although effects of individual exposures to both agents are well documented, there is a dearth of information on the effects of co-exposure to both agents. In this study, combined exposure to lead and DEHP was investigated for effects on ATPase activities in the liver, brain and kidney tissues of rats. Male albino rats were daily exposed to either 200 ppm lead as lead acetate in their drinking water and/or 100 mg DEHP kg-1 body weight in olive oil by gastric intubation for 30 days. Changes in total body weight, relative organ weights as well as brain, hepatic and renal activities of total, Na+K+ -, Ca2+ - and Mg2+-ATPases were used as biomarkers of toxicity. Hepatomegaly and brain atrophy heralded exposure to both agents. Individual exposure to lead and DEHP resulted in reduction in hepatic Ca2+- and Mg2+- ATPase activities but no significant effect on total ATPase activity, however combined exposure produced significant activation of Ca2+-, Na+K+- and total ATPase while restoring Mg2+ - ATPase towards control. A potentiating effect on lead by DEHP was observed in hepatic Na+K+ - ATPase. Lead stimulated the activities of renal Ca2+- and total ATPases while DEHP on the contrary caused significant reduction in total ATPase activity and no significant effects on Ca2+- ATPase activity. Co-treatment produced antagonistic effects leading to normal renal Ca2+- and total ATPase activities. Brain Na+K+ -, Ca2+ - and total ATPase activities were depressed in co-exposure while Mg2+ - ATPase was up-regulated. Lead potentiated DEHP-induced inhibition of brain total - ATPase while co-treatment produced antagonistic effects on brain Ca2+ - ATPase. The findings of this study highlight organ specific variations in response to combined lead and DEHP exposure in rats. Key words: Hepatotoxic, neurotoxic, ATPases, DEHP, lead, co-exposure, hepatomegaly.

The Long-Term DEHP Exposure Confers Multidrug Resistance of Triple-Negative Breast Cancer Cells through ABC Transporters and Intracellular ROS.

The characteristics of phthalates had been thought to be similar to endocrine disruptors, which increases cancer risk. The role of phthalates in acquired drug resistance remains unclear. In this study, we investigated the effect of di-(2-ethylhexyl) phthalate (DEHP) on acquired drug resistance in breast cancer. MCF7 and MDA-MB-231 breast cancer cells were exposed to long-term physiological concentration of DEHP for more than three months. Long-exposure DEHP permanently attenuated the anti-proliferative effect of doxorubicin with estrogen receptor-independent activity even after withdrawal of DEHP. Long term DEHP exposure significantly reduced ROS (O2−) level in MDA-MB-231 cells while increased in MCF7 cells. ATP-binding cassette (ABC) transporters possess a widely recognized mechanism of drug resistance and are considered a target for drug therapy. Upregulation of ABC family proteins, ABCB-1 and ABCC-1 observed in DEHP-exposed clones compared to doxorubicin-resistant (DoxR) and parental MDA-MB-231 cells. A viability assay showed enhanced multidrug resistance in DEHP-exposed clones against Dox, topotecan, and irinotecan. Inhibition of ABC transporters with tariquidar, enhanced drug cytotoxicity through increased drug accumulation reversing acquired multidrug resistance in MDA-MB-231 breast cancer cells. Tariquidar enhanced Dox cytotoxicity by increasing intracellular ROS production leading to caspase-3 mediated apoptosis. Activation of PI3K/Akt signaling enhanced proliferation and growth of DEHP-exposed MDA-MB-231 cells. Overall, long-term DEHP exposure resulted in acquired multidrug resistance by upregulating ABCB-1 and ABCC1; apart from proliferation PI3K/Akt may be responsible for acquired drug resistance through ABC transporter upregulation. Targeting ABCB1 and ABCC1 with tariquidar may be a promising strategy for reversing the acquired multidrug resistance of triple-negative breast cancer cells.

Paternal preconception phthalate exposure alters sperm methylome and embryonic programming

Preconception environmental conditions have been demonstrated to shape sperm epigenetics and subsequently offspring health and development. Our previous findings in humans showed that urinary anti-androgenic phthalate metabolites in males were associated with altered sperm methylation and blastocyst-stage embryo development. To corroborate this, we examined the effect of preconception exposure to di(2-ethylhexyl) phthalate (DEHP) on genome-wide DNA methylation and gene expression profiles in mice. Eight-week old C57BL/6J male mice were exposed to either a vehicle control, low, or high dose of DEHP (2.5 and 25 mg/kg/weight, respectively) for 67 days (~2 spermatogenic cycles) and were subsequently mated with unexposed females. Reduced representation bisulfite sequencing (RRBS) of epididymal sperm was performed and gastrulation stage embryos were collected for RRBS and transcriptome analyses in both embryonic and extra-embryonic lineages. Male preconception DEHP exposure resulted in 704 differentially methylated regions (DMRs; q-value < 0.05; ≥10% methylation change) in sperm, 1,716 DMRs in embryonic, and 3,181 DMRs in extra-embryonic tissue. Of these, 29 DMRs overlapped between sperm and F1 tissues, half of which showed concordant methylation changes between F0 and F1 generations. F1 transcriptomes at E7.5 were also altered by male preconception DEHP exposure including developmental gene families such as Hox, Gata, and Sox. Additionally, gene ontology analyses of DMRs and differentially expressed genes showed enrichment of multiple developmental processes including embryonic development, pattern specification and morphogenesis. These data indicate that spermatogenesis in adult may represent a sensitive window in which exposure to DEHP alters the sperm methylome as well as DNA methylation and gene expression in the developing embryo.

Correlations between Urinary Monoethylhexyl Phthalate Concentration in Healthy Individuals, Individuals with Colorectal Adenomas, and Individuals with Colorectal Cancer.

Colorectal cancer (CRC) is the third leading cause of cancer death in Taiwan. A recent study suggested a link between exposure to endocrine-disrupting chemicals (EDCs) and increased susceptibility to pathology. Exposure to di-(2-ethylhexyl) phthalate (DEHP), an EDC and plasticizer widely used in consumer products, has been reported to be significantly positively correlated with increased risks of various cancers. We explored this connection of DEHP exposure with the development of CRC through the detection of urinary monoethylhexyl phthalate (MEHP), a potent metabolite of DEHP. Participants comprised 221 individuals recruited between October 2016 and November 2019 from a single institution. Overall, urinary MEHP concentrations were significantly higher in patients with CRC than in the patients with adenoma or healthy participants (both P < 0.001). Higher exposure to DEHP may contribute to the occurrence of CRC. Urinary MEHP detection may serve as a beneficial noninvasive indicator of increased CRC risk.

The Interrelation of Environmental di-2-Ethylhexyl Phthalate (DEHP) and Melamine Exposure, Biomarkers of Oxidative Stress and Early Kidney Injury in Children and Adolescents Over Time-The 2011 Taiwan Food Scandal

Background: Exposure to di-(2-ethylhexyl) phthalate (DEHP)-tainted food from 2011 Taiwan food scandal increased children’s risk of microalbuminuria, possibly modified by melamine, was reported. This prospective cohort study is to investigate the temporal and interrelationship of exposure to DEHP-tainted foods, environmental DEHP exposure, and melamine, with markers of oxidative stress and renal injury over time. Methods: Children and adolescents possibly exposed to phthalate-tainted foodstuffs received surveys between August 2012 and October 2016 at first wave, second and third follow-up waves. Oxidative stress markers including malondialdehyde (MDA) and 8-oxo-2'-deoxyguanosine (8-OHdG), and renal injury markers including urine albumin/creatinine ratio (ACR) and N-acetyl-beta-D-glucosaminidase (NAG), were measured. Past DEHP exposure levels were categorized based on US EPA and European Food Safety Authority’s recommended tolerable daily intake levels, 20 and 50 μg/kg/day, respectively. Findings: Two hundred, 170, and 159 subjects were at the first, second, and third waves. General estimated equation modeling revealed significant main effects of past DEHP exposure and time on urinary ACR. When examining the temporal interaction of past DEHP exposure and time effect on urinary ACR, we found most of interaction variables were negative, but only the interaction of high past DEHP and second wave reached significant (P for interaction = 0.018). Current melamine exposure was significantly associated with urinary ACR, 8-OHdG, and MDA levels over time. Interpretation: DEHP-tainted food intake had its highest impact on increased urinary ACR at the beginning. This increase partially diminished over time. Environmental melamine exposure may increase urinary ACR and markers of oxidative stress over time. Funding: This work was financially supported by grants from Kaohsiung Medical University Hospital, (KMUH109-9R80); from The Featured Areas Research Center Program within the framework of the Higher Education Sprout Project by the Ministry of Education (MOE), Kaohsiung Medical University Research Center Grant (KMU- TC109A01); from Ministry of Science and Technology (MOST109-2314-B-037- 066; 109-2314-B-037-072-; 107-2314-B-037-109-); from National Health Research Institutes ( NHRI-EX110-10703PI), all in Taiwan. None of these institutions played any role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. Declaration of Interest: All authors have declared that no competing interests exist. Ethical Approval: This study was dubbed the RAPIT cohort and was approved by the Institutional Review Boards (IRBs) of NHRI, MHWHs, and KMUH.

Exposure to Di-2-ethylhexyl phthalate (DEHP) and infertility in women, NHANES 2013-2016

Di-2-ethylhexyl phthalate (DEHP) exposure is widespread in the general population and previous research has suggested that it contains endocrine-disrupting properties that can adversely affect the reproductive health system. The objective of this study was to use the 2013–2016 National Health and Nutrition Examination Survey (NHANES) data to assess the potential association between DEHP exposure and infertility in women. Using a nationally representative, cross-sectional study design, we used multiple logistic regression to measure the association of urinary metabolites of DEHP with self-reported history of infertility among women. Four metabolites of DEHP were examined: mono(2-ethylhexyl)phthalate (MEHP), mono(2-ethyl-5-hydroxy-hexyl)phthalate (MEHHP), mono(2-ethyl-5-oxy-hexyl) phthalate (MEOHP), and mono(2-ethyl-5-carboxy-pentyl)phthalate (MECPP). These metabolites were calculated into a molar sum of DEHP (∑DEHP) and split into quartiles for analysis. After adjusting for age and race, ∑DEHP was associated with increased odds of infertility for the second quartile (AOR = 2.35, 95% CI [1.24,4.44], p = 0.01) and third quartile (AOR = 2.83, 95% CI [1.57, 5.10], p < 0.01) when compared to the first quartile (reference). The adjusted OR for the highest quartile of ∑DEHP found no association and it was not statistically significant (AOR = 0.99, 95 %CI [0.57, 1.73], p = 0.98). The findings of this study add to the already complex existing literature on phthalate exposure and infertility. These findings warrant further population-based cohort studies on phthalate exposure and their relationship to infertility in humans.

Evaluation of reproductive hormones in Egyptian workers occupationally exposed to di-2-ethylhexyl phthalate (DEHP): a cross-sectional study.

Di-2-ethylhexyl phthalate (DEHP) is ubiquitous, known as an endocrine disruptor. DEHP is a widespread prevalence in general and occupational populations which raised great public concerns due to its potentially harmful health effects on the male reproductive system. We aimed to assess occupational levels of DEHP on gonadotropin and gonadal hormones including luteinizing hormone (LH), follicle-stimulating hormone (FSH), total testosterone (TT), and sex hormone binding globulin (SHBG) and evaluate its potential effects on Asp327Asn polymorphisms SHBG gene. We measured the levels of DEHP of 90 male workers in one of polyvinyl chloride (PVC) industry plant using enzyme-linked immunosorbent assay. Sex hormones were examined and Asp327Asn polymorphisms SHBG gene were detected by PCR-RFLP in all participants. The workers were divided into low- and high- DEHP exposed groups based on the geometric mean (GM) levels (183.86U/L) in serum. TT and TT: LH ratio were negatively correlated to DEHP levels (r=-0.213, p=0.038), (r=-0.225, p=0.027), respectively. The linear regression analysis revealed that a 10-fold increase of serum DEHP was found to be associated with 2.07 fold decreased in TT and a 2.26 fold decreased in TT/LH ratio. Serum testosterone is negatively associated with DEHP exposure in occupational workers.

Stereological analysis and transcriptome profiling of testicular injury induced by di-(2-ethylhexyl) phthalate in prepubertal rats

Di-(2-ethylhexyl) phthalate (DEHP) is the most common phthalate that can affect the male reproductive system. DEHP exposure at the prepubertal stage could lead to the injury of immature testes, but the mechanism has not been fully clarified. In the present study, we elucidated the possible underlying mechanism of DEHP-induced prepubertal testicular injury through stereological analysis and transcriptome profiling. Compared with the control group, the DEHP-treated rats had lower body weight gain and decreased testicular weight and organ coefficient. Moreover, lower serum levels of testosterone and LH were observed in the DEHP group, in contrast to the increased FSH level. Additionally, the serum level of estradiol had no significant difference after DEHP exposure. Stereological analysis showed significant reduction in volumes of most testicular structures, especially in the seminiferous tubule and seminiferous epithelium, along with a vast decrease of spermatogenic cells and obvious structural damages with substantial pathological signs (germ cracks, cytoplasmic vacuolization, sloughing, multinucleated giant cell formation, chromatolysis desquamation and dissolution, pyknosis of nuclei) in the seminiferous tubule upon DEHP exposure at the prepubertal stage. Furthermore, transcriptome profiling identified 5548 differentially expressed genes (DEGs) upon DEHP exposure. Pathway enrichment analysis revealed several crucial signaling pathways related to retinol metabolism, oxidative phosphorylation, steroid hormone biosynthesis, and cell adhesion molecules (CAMs). In addition, seven DEGs selected from RNA-seq data were validated by quantitative real-time polymerase chain reaction (qRT-PCR), and the results showed the same trends as the RNA-seq results. In conclusion, the above findings provide basic morphological data and lay a foundation for systematic research on transcriptome profiling in prepubertal testicular injury induced by DEHP.

Early-life chronic di(2-ethylhexyl)phthalate exposure worsens age-related long-term associative memory decline associated with insulin/IGF-1 signaling and CRH-1/CREB in Caenorhabditis elegans

The ubiquitous contamination of di(2-ethylhexyl)phthalate (DEHP) in the environment, biota, and food poses potential ecological and human health risks. DEHP exposure can adversely affect learning and memory, yet the underlying mechanisms remain unclear. In this study, Caenorhabditis elegans was used to investigate the effect of early-life DEHP exposure on age-related long-term associative memory (LTAM) decline, as well as the associations with the cAMP-responsive element-binding protein (CREB) transcription factor and insulin/IGF-1 signaling (IIS). We showed that early-life exposure to DEHP reduced LTAM in wild-type worms at day-0 adulthood. Chronic exposure to DEHP from the L1 stage to day-5 adulthood worsened the age-dependent decline of LTAM. Moreover, the effect of DEHP on age-related LTAM requires CRH-1, a homolog of CREB. Mutations in daf-2, the sole receptor of C. elegans IIS, ameliorated the inhibition of LTAM by DEHP, and the effect depended on daf-16. In addition, daf-2 mutation restored the CRH-1 level in DEHP-exposed worms, and the effect required daf-16. Our study suggests that early-life chronic exposure to DEHP worsens age-related LTAM decline and the effect is associated with CRH-1 and IIS in C. elegans. The evolutionary conservation of IIS and CREB implies possible adverse effects by DEHP across species.