Phthalate-induced oxidative stress and association with asthma-related airway inflammation in adolescents

Inverse associations of bisphenol A and phthalate metabolites with serum bilirubin levels in Korean population

Bisphenol A (BPA) and phthalates are endocrine disruptors that can induce oxidative stress. Serum bilirubin has antioxidant properties and may serve as a biomarker of oxidative stress. The objective of this study was to explore the relationship of BPA and phthalates with serum bilirubin levels in a Korean population. Urinary concentrations of BPA and six phthalate [mono-n-butyl phthalate (MnBP), mono-iso-butyl phthalate (MiBP), mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP), mono-(2-ethyl-5- hydroxyhexyl) phthalate (MEHHP), mono-(2-ethyl-5-carboxypentyl) phthalate (MECPP), and mono-benzyl phthalate (MBzP)] were measured in 709 participants. Serum concentrations of BPA and three phthalate metabolites [MnBP, MiBP, and mono-(2-ethylhexyl) phthalate (MEHP)] were measured in 752 participants. After excluding missing variables, associations between above chemicals and serum bilirubin levels were analyzed using multivariate linear regression with age, sex, BMI, GGT, GOT, GPT, and alcohol intake adjustment. Participants were further stratified by sex. Among the urinary chemicals, BPA and four phthalate metabolites (MnBP, MEOHP, MEHHP and MECPP) were inversely associated with serum bilirubin levels (BPA: β = - 0.071, P < 0.0001; MnBP: β = - 0.055, P = 0.025; MEOHP: β = - 0.101, P < 0.0001; MEHHP: β = - 0.106, P < 0.0001; MECPP: β = - 0.052, P = 0.003). In a case of serum chemicals, only MiBP showed significantly positive association (β = 0.036, P = 0.016). After stratification by sex, the associations of urinary BPA remained both in male and female, of which urinary phthalates disappeared in female. The association of serum MiBP was disappeared after stratification. Urinary BPA and phthalate metabolites were inversely associated with serum bilirubin levels, whereas serum MiBP showed positive association with bilirubin. These results could provide clues for understanding the mechanisms of endocrine disruptor from oxidative stress to excretion from our body.

Beyond the antibodies: serum metabolomic profiling of myasthenia gravis

INTRODUCTION

Myasthenia gravis (MG) is a chronic, potentially debilitating autoimmune disease characterized by weakness and rapid fatigue of the voluntary muscles that worsens on exertion. Left untreated, MG symptoms may cause significant morbidity or even death. To date, no robust biological marker is available to follow the course of the disease. Therefore, new diagnostic approaches and biological markers are essential not only for improved diagnosis of the disease but for improved outcomes.

OBJECTIVES

The present study applied a two-control, multi-label metabolomics profiling approach as a potential strategy for the identification of biomarkers unique to myasthenia gravis (MG).

METHODS

Metabolic analyses using acid- and dansyl-labelled serum from seropositive MG (n = 46), rheumatoid arthritis (RA) (n = 23) and healthy controls (HC) (n = 49) were performed on samples from adult patients presenting to the University of Alberta Hospital neuromuscular and rheumatology clinics. Comparisons between patients with MG vs. HC, and RA vs. HC were made using univariate and multivariate statistics.

RESULTS

Serum biomarker patterns were statistically significantly different between groups. Principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) models exhibited considerable distinction between all groups. Metabolites were then filtered to remove peak pairs common to both disease cohorts. Combined metabolite panels revealed clear separation between MG and HC for both library-matched (AUROC: 0.92 ± 0.03) and highest AUC patients (AUROC: 0.94 ± 0.05).

CONCLUSION

In patients presenting to the clinic with seropositive MG, metabolomic profiling is capable of distinguishing patients with disease from those without. These results provide an important first step towards a potential biomarker for improving MG identification.

Encircling granulosa cells protects against di-(2-ethylhexyl)phthalate-induced apoptosis in rat oocytes cultured in vitro

The present study investigated if the presence of encircling granulosa cells protected against di(2-ethylhexyl)phthalate (DEHP)-induced oxidative stress in rat oocytes cultured in vitro. Denuded oocytes and cumulus–oocyte complexes (COCs) were treated with or without various doses of DEHP (0.0, 25.0, 50.0, 100, 200, 400 and 800 μM) in vitro. Morphological apoptotic changes, levels of oxidative stress and reactive oxygen species (ROS), mitochondrial membrane potential, and expression levels of apoptotic markers (Bcl2, Bax, cytochrome c) were analyzed. Our results showed that DEHP induced morphological apoptotic changes in a dose-dependent manner in denuded oocytes cultured in vitro. The effective dose of DEHP (400 µg) significantly (P>0.05) increased oxidative stress by elevating ROS levels and the mitochondrial membrane potential with higher mRNA expression and protein levels of apoptotic markers (Bax, cytochrome c). Encircling granulosa cells protected oocytes from DEHP-induced morphological changes, increased oxidative stress and ROS levels, as well as increased expression of apoptotic markers. Taken together our data suggested that encircling granulosa cells protected oocytes against DEHP-induced apoptosis and that the presence of granulosa cells could act positively towards the survival of oocytes under in vitro culture conditions and may be helpful during assisted reproductive technique programmes.

Exposure to indoor endocrine-disrupting chemicals and childhood asthma and obesity

BACKGROUND

Indoor air contaminants may act as endocrine-disrupting chemicals (EDCs). However, to what extent these contaminants affect health is poorly known. We aimed to assess the association between EDCs exposure and asthma, respiratory symptoms and obesity in schoolchildren.

METHODS

Data from a cross-sectional analysis of 815 participants from 20 schools in Porto, Portugal, were analysed. Symptoms were assessed, asthma was defined on lung function, and airway reversibility and body mass index (BMI) were calculated. The concentrations of 13 volatile organic compounds and 2 aldehydes identified as EDCs were measured in 71 classrooms throughout 1 week. Principal component analysis (PCA) was used to assess the effect of co-exposure. Associations were estimated by regression coefficients using linear and logistic regression models.

RESULTS

Increased individual and combined EDCs levels were found in classrooms having more children with asthma and obesity. Higher levels of hexane, styrene, cyclohexanone, butylated hydroxytoluene and 2-butoxyethanol were associated with obesity, and higher levels of cyclohexanone were associated with increased child BMI. Toluene, o-xylene, m/p-xylene and ethylbenzene were significantly associated with nasal obstruction. A positive association was found between PC1 and the risk of obese asthma (OR = 1.43, 95% CI 1.01, 1.98) and between PC2 and overweight (OR = 1.51, 95% CI 1.28, 1.79). PC1 and PC2 were also associated with nasal obstruction, and PC2 was associated with breathing difficulties and lean body mass, although EDCs concentrations were low.

CONCLUSIONS

Our findings further support the role of EDCs in asthma and obesity development. Moreover, even low levels of indoor exposure may influence the risk of asthma, respiratory symptoms and obesity.

Environmental ototoxicants, a potential new class of chemical stressors

Hearing loss is an injury that can develop over time, and people may not even be aware of it until it becomes a severe disability. Ototoxicants are substances that may damage the inner ear by either affecting the structures in the ear itself or by affecting the nervous system. We have examined the possibility that ototoxicants may present a health hazard in association with environmental exposures, adding to existing knowledge of their proven hazards under medical therapeutic conditions or occupational activities. In addition to the already described human environmental ototoxicants, mainly organochlorines such as polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), dichlorodiphenyltrichloroethane (DDT), dichlorodiphenyldichloroethylene (DDE), hexachlorocyclohexane (HCH) and hexachlorobenzene (HCB), we have examined the ubiquitous chemical stressors phthalates, bisphenol A/S/F/, PFCs, flame retardants (FRs) and cadmium for potential ototoxic properties, both as single substances or as chemical mixtures. Our literature review confirmed that these chemicals may disturb thyroid hormones homeostasis, activate aryl hydrocarbon receptor (AhR), and induce oxidative stress, which in turn may initiate a chain of events resulting in impairment of cochlea and hearing loss. With regard to auditory plasticity, diagnostics of a mixture of effects of ototoxicants, potential interactions of chemical and physical agents with effects on hearing, parallel deterioration of hearing due to chemical exposures and ageing, metabolic diseases or obesity, even using specific methods as brainstem auditory evoked potentials (BAEP) or otoacoustic emissions (OAEs) registration, may be difficult, and establishment of concentration-response relationships problematic. This paper suggests the establishment of a class of environmental oxotoxicants next to the established classes of occupational and drug ototoxicants. This will help to properly manage risks associated with human exposure to chemical stressors with ototoxic properties and adequate regulatory measures.

Designing Rosin-Based Plasticizers: Effect of Differently Branched Chains on Plasticization Performance and Solvent Resistance of Flexible Poly(vinyl chloride) Films

In the present study, we report a strategy to prepare rosin-based plasticizers with differently branched chains, which have the same benzene ring and similar alkane structure compared to phthalate plasticizers. Castor oil methyl ester, cardanol, and triethyl citrate were reacted with the chemical structure of rosin-based plasticizers. Rosin-based plasticizers with differently branched chains as alternative plasticizers for preparing phthalate-free flexible poly(vinyl chloride) films. All rosin-based plasticizers exhibited more excellent solvent extraction performance than phthalate plasticizers in four different solvents. The plasticizing efficiency of rosin-based plasticizers containing triethyl citrate groups reached 85.5%. The relationships between plasticizing efficiency, thermal stability, solvent resistance, tensile properties, and relative molecular mass of the branched chains of rosin-based plasticizers were investigated.

Neurochemical alterations following the exposure to di-n-butyl phthalate in rats

Due to its ability to cross blood brain barrier and placenta, dibutyl phthalate (di-n-butyl phthalate, DBP) is expected to cause severe side effects to the central nervous system of animals and humans. A little data is available about the potential DBP neurotoxicity; therefore, this work was designed to investigate the brain tissue injury induced by DBP exposure. Forty Wister albino rats were allocated randomly into 4 groups (10 rats each). Group 1 served as control and the rats administered with physiological saline (0.9% NaCl) orally for 12 weeks. Groups 2, 3 and 4 were orally treated with DPB (100, 250 and 500 mg/kg) respectively for 12 weeks. DBP-intoxicated rats showed a disturbance in the oxidative status in cerebral cortex, striatum and brainstem, as represented by the elevated oxidants [malondialdehyde (MDA), nitric oxide (NO), 8-hydroxy-2-deoxyguanosine (8-OHdG)] and the decreased antioxidant molecules [reduced glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR)]. DBP also enhanced a pro-inflammatory state through increasing the release of tumor necrosis factor- α (TNF-α) and interleukin-1β (IL-1β). The increase of these cytokines was associated with the increase of pro-apoptotic proteins [Bcl-2 associated X protein (Bax) and caspase-3] and the decrease of the anti-apoptotic protein, B cell lymphoma 2 (Bcl-2). In addition, the levels of norepinephrine (NE), dopamine (DA) and acetylcholine esterase (AChE) activity were decreased. This was accompanied by the alterations in the major excitatory and inhibitory amino acids neurotransmitters levels. The present findings indicated that DBP could exert its neuronal damage through oxidative stress, DNA oxidation, neuroinflammation, activation of apoptotic proteins and altering the monoaminergic, cholinergic and amino acids transmission.

Systems analysis of the liver transcriptome in adult male zebrafish exposed to the non-ionic surfactant nonylphenol

Nonylphenol (NP) arises from the environmental degradation of nonylphenol ethoxylates. It is a ubiquitous environmental contaminant and has been detected at levels up to 167 nM in rivers in the United States. NP is an endocrine disruptor (ED) that can act as an agonist for estrogen receptors. The Adverse Outcome Pathway (AOP) framework defines an adverse outcome as the causal result of a series of molecular initiating events (MIEs) and key events (KEs) that lead to altered phenotypes. This study examined the liver transcriptome after a 21 day exposure to NP and 17β-estradiol (E2) by exploiting the zebrafish (Danio rerio) as a systems toxicology model. The goal of this study was to tease out non-estrogenic genomic signatures associated with NP exposure using DNA microarray and RNA sequencing. Our experimental design included E2 as a positive and potent estrogenic control in order to effectively compare and contrast the 2 compounds. This approach allowed us to identify hepatic transcriptomic perturbations that could serve as MIEs for adverse health outcomes in response to NP. Our results revealed that exposure to NP was associated with differential expression (DE) of genes associated with the development of steatosis, disruption of metabolism, altered immune response, and metabolism of reactive oxygen species, further highlighting NP as a chemical of emerging concern (CEC).

Adiponectin alleviates exacerbation of airway inflammation and oxidative stress in obesity-related asthma mice partly through AMPK signaling pathway

Adiponectin plays a role in asthma and obesity, but its effects and mechanism in obesity-related asthma remain elusive. This study aimed to evaluate the effects of adiponectin on airway inflammation and oxidative stress and to determine its mechanism in obesity-related asthma. Male C57BL6/J mice fed with a high-fat diet to induce obesity were sensitized and challenged with ovalbumin to induce asthma, and treated with adiponectin (1 mg/kg) and AMP-activated protein kinase (AMPK) inhibitor compound C (20 mg/kg) twice before the first ovalbumin challenge. We found exogenous adiponectin significantly reduced airway resistance, inflammatory infiltration in lung tissue, and cell counts in bronchoalveolar lavage fluid. Adiponectin inhibited great levels of eotaxin, myeloperoxidase, tumor necrosis factor-α, 8‑hydroxy‑2'‑deoxyguanosine, and nitric oxide in obesity-related asthma mice. Moreover, we found increased nuclear factor kappa B p65, inducible nitric oxide synthase and B-cell lymphoma 2 protein expression were down-regulated with adiponectin administration. Additionally, adiponectin elevated the lower levels of pAMPK and AMPK activity in lung tissue. These protective effects of adiponectin were reversed after treatment with the AMPK inhibitor compound C. Thus, we conclude that adiponectin alleviates exacerbation of airway inflammation and oxidative stress in a murine model of obesity-related asthma partly through AMPK signaling pathway.

Urinary phthalate metabolites in relation to childhood asthmatic and allergic symptoms in Shanghai

BACKGROUND

Few studies can be found on phthalate exposure in relation to childhood asthma and allergic symptoms from Mainland China, where a persistent increase in prevalence of childhood asthma and allergic disease has been observed.

OBJECTIVES

This study aimed to assess the exposure levels to phthalates and its relationship with asthmatic and allergic symptoms among children in Shanghai, which has the highest prevalence of childhood asthma in Mainland China.

METHODS

A follow-up study (2013-2014) of 434 children aged 5-10 years was conducted, based on the China, Children, Homes, Health (CCHH) study (2011-2012) in Shanghai, China. Information on asthmatic and allergic symptoms (wheeze, rhinitis, and eczema) were collected using validated questionnaires. Ten phthalate metabolites in morning urine samples were analyzed by high-performance liquid chromatography with triple quadrupole tandem mass spectrometry (HPLC-MS/MS). Multivariable logistic regression was used to estimate the associations between symptoms and urinary phthalate metabolites controlling for demographics, family history of allergic diseases and other covariates.

RESULTS

Nine out of 10 phthalate metabolites were detected in all subjects (average detection rate of 93.2%). By multivariable logistic regression analyses, the 4th quartile of Mono‑n‑butyl phthalate (MnBP) (reference: 1st quartile) had adjusted prevalence odds ratios (aPOR_S) and 95% confidence intervals (95%CIs) of 2.27(1.06-4.88), 2.14(1.02-4.46) and 2.98(1.19-7.50) for wheeze, rhinitis and eczema, respectively, while those of Mono‑isobutyl phthalate (MiBP) were 2.23(1.08-4.62) and 2.96(1.02-8.60) for rhinitis and eczema, respectively. The highest quartile of mono‑2‑ethyl‑5‑hydroxyhexyl phthalate(MEHHP) and mono‑2‑ethyl‑5‑oxohexyl phthalate(MEOHP) had aPOR_S and 95%CIs of 3.10(1.10-8.74) and 2.63(1.02-6.80) for eczema, respectively. By summing up the 4 low molecular weight metabolites (∑₄LMWP) and all 9 metabolites (∑₉Total), the highest quartiles of ∑₄LMWP and∑₉Total were significantly associated with all symptoms. In most of the above associations, a significantly increasing trend from the 1st to the 4th quartile was observed. Subjects with 2 or 3 concomitant symptoms (reference: no symptoms) had significant positive associations with a higher level (the 4th quartile) of phthalate metabolites.

CONCLUSIONS

Low MW metabolites such as MnBP and MiBP, high MW DEHP and the total amount of phthalate metabolites might have adverse health effects on asthma and allergic symptoms in Chinese children.

Phthalates and organophosphates in settled dust and HVAC filter dust of U.S. low-income homes: Association with season, building characteristics, and childhood asthma

Phthalates and organophosphates are ubiquitous indoor semi-volatile organic contaminants (SVOCs) that have been widely used as plasticizers and flame retardants in consumer products. Although many studies have assessed their levels in house dust, only a few used dust samples captured by filters of building heating, ventilation, and air conditioning (HVAC) systems. HVAC filters collect particles from large volumes of air over a long period of time (potentially known) and thus provide a spatially and temporally integrated concentration. This study measured concentrations of phthalates and organophosphates in HVAC filter dust and settled floor dust collected from low-income homes in Texas, United States, in both the summer and winter seasons. The most frequently detected compounds were benzyl butyl phthalate (BBzP), di-(2-ethylhexyl) phthalate (DEHP), di-n-octyl phthalate (DnOP), tris (1-chloro-2-propyl) phosphate (TCIPP), triphenyl phosphate (TPHP), and tris (1,3-dichloroisopropyl) phosphate (TDCIPP). The median level of TCIPP in settled dust was 3- to 180-times higher than levels reported in other studies of residential homes. Significantly higher concentrations were observed in HVAC filter dust as compared to settled dust for most of the frequently detected compounds in both seasons, except for several phthalates in the winter. SVOC concentrations in settled dust in winter were generally higher than in summer, while different seasonality patterns were found for HVAC filter dust. Settled dust samples from homes with vinyl flooring contained significantly higher levels of BBzP and DEHP as compared to homes with other types of floor material. The concentration of DEHP and TDCIPP in settled dust also significantly associated with the presence of carpet in homes. Cleaning activities to remove dust from furniture actually increased the levels of certain compounds in HVAC filter dust, while frequent vacuuming of carpet helped to decrease the concentrations of some compounds in settled dust. Additionally, the size and age of a given house also correlated with the levels of some pollutants in dust. A statistically significant association between DEHP concentration in HVAC filter dust in summer and the severity of asthma in children was observed. These results suggest that HVAC filter dust represents a useful sampling medium to monitor indoor SVOC concentrations with high sensitivity; in contrast, when using settled dust, in addition to consideration of seasonal influences, it is critical to know the sampling location because the type and level of SVOCs may be related to local materials used there.

Phthalate Exposure from Drinking Water in Romanian Adolescents

Phthalates are plastic softeners that have been linked to several adverse health outcomes. The relative contributions of different sources to phthalate exposure in populations in different regions and at different life stages is unclear. We examined the relationships between water consumption, consumer product use, and phthalate exposure among 40 adolescents (20 males, 20 females) in Cluj-Napoca, Romania. Interviewers administered a questionnaire about drinking water consumption and use of phthalate-containing consumer products. Four common phthalates were measured in representative samples of participants’ municipal drinking water and consumed bottled water using gas chromatography-mass spectrometry. Urine samples were collected from participants and analyzed for the corresponding phthalate metabolites. Relationships between different exposure measures were assessed using nonparametric tests (Spearman rank correlation coefficients and the Kruskal–Wallis test). Diisobutyl phthalate, dibutyl phthalate, and bis(2-ethylhexyl) phthalate were commonly detected in bottled water, but generally not the municipal drinking water samples. Mono-n-butyl phthalate (MnBP) was the most commonly detected urinary metabolite (detected in 92.5% of participants) and had the highest maximum concentration (1139.77 µg/g creatinine). We did not identify any statistically significant associations between water consumption or consumer product use practices and urinary phthalate metabolite concentrations in our adolescent group, and directions of correlation coefficients differed by individual phthalate compound. While phthalate exposure was widespread, these results highlight the challenges in examining phthalate exposure determinants and emphasize the need for further investigation into understanding exposure sources and potential health risks from chronic low-level exposures.

Plasticizer, di(2-ethylhexyl)phthalate (DEHP) enhances cockroach allergen extract-driven airway inflammation by enhancing pulmonary Th2 as well as Th17 immune responses in mice

In recent decades, there has been a gradual increase in the prevalence of asthma. Various factors including environmental pollutants have contributed to this phenomenon. Plasticizer, di(2-ethylhexyl)phthalate (DEHP) is one of the commonest environmental pollutants due to its association with plastic products. DEHP gets released from plastic products easily leading to respiratory exposure in humans. As a consequence, DEHP is associated with allergic asthma in humans and animals. DEHP is reported to act as an adjuvant in ovalbumin-induced mouse models of asthma at high doses. However, these studies mostly looked into the role of DEHP on Th2 cytokines/eosinophilic inflammation without investigating the role of airway epithelial cells (AECs)/dendritic cells (DCs)/Th17 cells. Its adjuvant activity with natural allergens such as cockroach allergens at tolerable daily intake needs to be explored. Cockroach allergens and DEHP may be inhaled together due to their coexistence in work place as well as household environments. Therefore, effect of DEHP was assessed in cockroach allergens extract (CE)-induced mouse model of asthma. Airway inflammation, histopathology, mucus secretion, and immune responses related to Th2/Th17/DCs and AECs were assessed in mice with DEHP exposure alone and in combination with CE. Our study shows that DEHP converts CE-induced eosinophilic inflammation into mixed granulocytic inflammation by promoting Th2 as well as Th17 immune responses. This was probably due to downregulation of E-cadherin in AECs, and enhancement of costimulatory molecules (MHCII/CD86/CD40)/pro-inflammatory cytokines (IL-6/MCP-1) in DCs by DEHP. This suggests that DEHP facilitates development of mixed granulocytic airway inflammation in the presence of a natural allergen.

Association of phthalate exposures with urinary free cortisol and 8-hydroxy-2'-deoxyguanosine in early childhood

Several studies suggested potential links of phthalates to stress-related outcomes. However, limited evidence has been available for the relationships between phthalate metabolites and free cortisol and 8-hydroxy-2'-deoxyguanosine (8-OHdG) in perinatal and postnatal environments. Therefore, we evaluated the relationships between phthalate metabolites and free cortisol and 8-OHdG in mother-child pairs. We repeatedly collected urine samples of 287 mother-child pairs from just before delivery to 15 months of age to measure the levels of four phthalate metabolites - mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP), mono-isobutyl phthalate (MiBP), and mono-n-butyl phthalate (MnBP) - and free cortisol and 8-OHdG. We used linear mixed effect models and generalized additive mixed models to estimate the relationship between the phthalate metabolites and free cortisol and 8-OHdG after adjusting for the child's gender, urine collection time, and maternal smoking status. The four phthalate metabolite levels were strongly correlated each other (all, p < .0001), and intra-class correlation for each metabolite in children ranged from 0.18 to 0.96. All four phthalate metabolites were positively associated with both free cortisol (MEHHP, β = 0.18 and p < .0001; MEOHP, β = 0.17 and p < .0001; MiBP, β = 0.13 and p = .0001; MnBP, β = 0.21 and p < .0001; and molar sum of metabolites, β = 0.21 and p < .0001) and 8-OHdG (MEHHP, β = 0.20 and p < .0001; MEOHP, β = 0.18 and p < .0001; MiBP, β = 0.23 and p < .0001; MnBP, β = 0.28 and p < .0001; and molar sum of metabolites, β = 0.29 and p < .0001) in childhood. Our findings suggest that phthalate exposures increase free cortisol and 8-OHdG levels in early childhood.

Urinary phthalate metabolite concentrations in girls with premature thelarche

In girls, breast development before eight years of age is called "premature thelarche (PT)". There are few studies in literature that show the interaction between PT and phthalate exposure. The aim of this study was to determine the urinary levels of di-(2-ethylhexyl) phthalate (DEHP) metabolites and other phthalate metabolites in girls with PT. PT group consisted of 29 newly diagnosed subjects. Control group comprised of healthy age-matched girls (n = 25). Urinary phthalate metabolite concentrations were measured by liquid chromatography/tandem mass spectroscopy (LC-MS/MS). The urinary concentrations of mono-(2-ethyl-hexyl)phthalate (MEHP) in the PT group (33.96 ± 6.88 μg/g creatinine) were found to be significantly higher compared to control group (11.54 ± 1.39 μg/g creatinine, p = 0.002). In PT group, %MEHP was also markedly higher vs. control (17.84 ± 3.31 vs. 6.44 ± 1.13, p = 0.001). Our results suggest that DEHP is more efficiently converted to MEHP in girls with PT, the importance of which needs to be further elucidated.

Systems Analysis of the Liver Transcriptome in Adult Male Zebrafish Exposed to the Plasticizer (2-Ethylhexyl) Phthalate (DEHP)

The organic compound diethylhexyl phthalate (DEHP) represents a high production volume chemical found in cosmetics, personal care products, laundry detergents, and household items. DEHP, along with other phthalates causes endocrine disruption in males. Exposure to endocrine disrupting chemicals has been linked to the development of several adverse health outcomes with apical end points including Non-Alcoholic Fatty Liver Disease (NAFLD). This study examined the adult male zebrafish (Danio rerio) transcriptome after exposure to environmental levels of DEHP and 17α-ethinylestradiol (EE2) using both DNA microarray and RNA-sequencing technologies. Our results show that exposure to DEHP is associated with differentially expressed (DE) transcripts associated with the disruption of metabolic processes in the liver, including perturbation of five biological pathways: ‘FOXA2 and FOXA3 transcription factor networks’, ‘Metabolic pathways’, ‘metabolism of amino acids and derivatives’, ‘metabolism of lipids and lipoproteins’, and ‘fatty acid, triacylglycerol, and ketone body metabolism’. DE transcripts unique to DEHP exposure, not observed with EE2 (i.e. non-estrogenic effects) exhibited a signature related to the regulation of transcription and translation, and ruffle assembly and organization. Collectively our results indicate that exposure to low DEHP levels modulates the expression of liver genes related to fatty acid metabolism and the development of NAFLD.