An assessment of the ability of phthalates to influence immune and allergic responses

Perinatal androgens organize sex differences in mast cells and attenuate anaphylaxis severity into adulthood

Mast cell (MC)-associated diseases, including allergy/anaphylaxis and neuroinflammatory pain disorders, exhibit a sex bias, with females at increase risk. While much attention has been directed toward adult sex hormones as drivers of sex differences, that female sex bias in MC-associated diseases is evident in prepubertal children, suggesting early-life origins of sex differences which have yet to be explored. Utilizing rodent models of MC-mediated anaphylaxis, our data here reveal that, 1) compared with females, males exhibit significantly reduced severity of MC-mediated anaphylactic responses that emerge prior to puberty and persist into adulthood, 2) reduced severity of MC-mediated anaphylaxis in males is linked with the naturally high level of perinatal androgens and can be recapitulated in females by perinatal exposure to testosterone proprionate, 3) perinatal androgen exposure guides bone marrow MC progenitors toward a masculinized tissue MC phenotype characterized by decreased concentration of prestored MC granule mediators (e.g., histamine, serotonin, and proteases) and reduced mediator release upon degranulation, and 4) engraftment of MC-deficient Kit W-sh/W-sh mice with adult male, female, or perinatally androgenized female MCs results in MC-mediated anaphylaxis response that reflects the MC sex and not host sex. Together, these data present evidence that sex differences in MC phenotype and resulting disease severity are established in early life by perinatal androgens. Thus, factors affecting levels of perinatal androgens could have a significant impact on MC development and MC-associated disease risk across the life span.

Bioremediation of di-(2-ethylhexyl) phthalate contaminated red soil by Gordonia terrae RL-JC02: Characterization, metabolic pathway and kinetics

Di-(2-ethylhexyl) phthalate (DEHP) is the most widely used plasticizer and a representative endocrine disrupting chemical. The toxicological effects of DEHP on environmental and human health have been widely investigated. In this study, the DEHP-degrading bacterial strain RL-JC02 was isolated from red soil with long-term usage of plastic mulch, and it was identified as Gordonia terrae by 16S rRNA gene analysis coupled with physiological and biochemical characterization. The biodegrading capacity of different phthalic acid esters and related intermediates was investigated as well as the performance of strain RL-JC02 under different environmental conditions, such as temperature, pH, salinity and DEHP concentration. Specifically, strain RL-JC02 showed good tolerance to low pH, with 86.6% of DEHP degraded under the initial pH of 5.0 within 72 h. The metabolic pathway of DEHP was examined by metabolic intermediate identification via a high-performance liquid chromatography coupled with mass spectrometry (HPLC-MS) analysis in which DEHP was hydrolyzed into phthalic acid (PA) and 2-ethylhexanol (2-EH) via mono (2-ethylhexyl) phthalate (MEHP). PA and 2-EH were further utilized through the protocatechuic acid metabolic pathway and β-oxidation via protocatechuic acid and 2-ethylhexanoic acid, respectively. The application potential of strain RL-JC02 was confirmed through the bioremediation of artificial DEHP-contaminated red soil showing 91.8% DEHP degradation by strain RL-JC02 within 30 d. The kinetics analysis of DEHP degradation by strain RL-JC02 in soil demonstrated that the process followed the modified Gompertz model. Meanwhile, the cell concentration monitoring of strain RL-JC02 in soil with absolute quantification polymerase chain reaction (qPCR) suggested that strain RL-JC02 survived well during bioremediation. This study provides sufficient evidence of a robust degrader for the bioremediation of PAE-contaminated red soil.

Critical Review on the Presence of Phthalates in Food and Evidence of Their Biological Impact

Phthalates are a huge class of chemicals with a wide spectrum of industrial uses, from the manufacture of plastics to food contact applications, children's toys, and medical devices. People and animals can be exposed through different routes (i.e., ingestion, inhalation, dermal, or iatrogenic exposure), as these compounds can be easily released from plastics to water, food, soil, air, making them ubiquitous environmental contaminants. In the last decades, phthalates and their metabolites have proven to be of concern, particularly in products for pregnant women or children. Moreover, many authors reported high concentrations of phthalates in soft drinks, mineral waters, wine, oil, ready-to-eat meals, and other products, as a possible consequence of their accumulation along the food production chain and their accidental release from packaging materials. However, due to their different physical and chemical properties, phthalates do not have the same human and environmental impacts and their association to several human diseases is still under debate. In this review we provide an overview of phthalate toxicity, pointing out the health and legal issues related to their occurrence in several types of food and beverage.

Biodegradation of phthalate esters by Paracoccus kondratievae BJQ0001 isolated from Jiuqu (Baijiu fermentation starter) and identification of the ester bond hydrolysis enzyme

Phthalate ester (PAE) pollution is an increasing problem globally. Paracoccus kondratievae BJQ0001 was isolated from the fermentation starter of Baijiu and showed an efficient degradation capability toward PAEs. To our poor knowledge, this is the first report of a P. kondratievae strain capable of degrading PAEs. The first complete genome sequence of P. kondratievae was presented without gaps, and composed of two circular chromosomes and one plasmid. The species simultaneously degraded di-methyl phthalate (DMP), di-ethyl phthalate (DEP), di-butyl phthalate (DBP), di-isobutyl phthalate (DIBP) and di-(2-ethylhexyl) phthalate (DEHP), with DMP and DEP as the preferred substrates. The half-life (t_1/2) of DMP was only 6.34 h with an initial concentration of 200 mg/L. Combined with gene annotation and metabolic intermediate analysis, a metabolic pathway was proposed for the species. Benzoic acid, the intermediate of anaerobic PAE metabolism, was identified in the aerobic degradation process. Two key enzymes for alkyl ester bond hydrolysis were obtained, and belonged to families IV and VI of hydrolases, respectively. These results will promote the investigation of PAE degradation by P. kondratievae, and provide useful information for improving the quality control of food and environmental PAE treatment.

DEHP induces neutrophil extracellular traps formation and apoptosis in carp isolated from carp blood via promotion of ROS burst and autophagy

Di (2-ethylhexyl) phthalate (DEHP), a widely spreading environmental endocrine disruptor, has been confirmed to adversely affect the development of animals and humans. The formation of neutrophil extracellular traps (NETs) termed NETosis, is a recently identified antimicrobial mechanism for neutrophils. Though previous researches have investigated inescapable role of the immunotoxicity in DEHP-exposed model, relatively little is known about the effect of DEHP on NETs. In this study, carp peripheral blood neutrophils were treated with 40 and 200 μmol/L DEHP to investigate the underlying mechanisms of DEHP-induced NETs formation. Through the morphological observation of NETs and quantitative analysis of extracellular DNA, we found that DEHP exposure induced NETs formation. Moreover, our results proved that DEHP could increase reactive oxygen species (ROS) levels, decrease the expression of the anti-autophagy factor (mTOR) and the anti-apoptosis gene Bcl-2, and increase the expression of pro-autophagy genes (Dynein, Beclin-1 and LC3B) and the pro-apoptosis factors (BAX, Fas, FasL, Caspase3, Caspase8, and Caspase9), thus promoting autophagy and apoptosis. These results indicate that DEHP-induced ROS burst stimulates NETs formation mediated by autophagy and increases apoptosis in carp neutrophils.

The occurrence and spatial distribution of phthalate esters (PAEs) in the Lanzhou section of the Yellow River

The occurrence and spatial distribution of 22 congener phthalate esters (PAEs) in the Lanzhou section of the Yellow River were investigated using water and sediment samples collected from 12 stations along the river in August 2016 to March 2017. PAEs were determined by liquid-liquid extraction and gas chromatography-mass spectrometry. The average concentrations of PAE in the water samples during the dry and wet periods were 3236.0 ng/L and 2300.0 ng/L, and the average dry and wet periods of the PAEs in the sediments were 4238.9 ng/g and 3959.9 ng/g, respectively. PAEs were detected in all sampling sites. The six PAEs controlled by the United States Environmental Protection Agency (U.S. EPA), namely dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), di-2-ethylhexyl phthalate (DEHP), di-n-octyl phthalate (DNOP), and butyl benzyl phthalate(BBP), were detected. DMP, DEP, DBP, and DEHP accounted for more than 70% of all PAEs. In view of time distribution, PAEs concentration in the water samples of the dry season were greater than those of the wet season, but the sediments did not differ remarkably across the different periods. As for spatial distribution, the PAEs initially exhibited low concentrations in the upper reaches, high concentrations in the middle part, and low concentrations in the downstream; a health risk assessment of the six PAEs controlled by the U.S. EPA was carried out according to priority. Results showed that the carcinogenic risk value was less than 10^-6, and the values of the non-carcinogenic compound risk index were less than 1, indicating the absence of carcinogenic damage to organisms or humans.

[Extended understanding of pathogenesis and treatment of contact allergy]

BACKGROUND

While the pathogenesis of contact allergy in recent years has increasingly focused on the mechanisms of the innate immune response, valid therapeutic options are still lacking.

AIMS

This article intends to shed light on the background of contact allergy development as well as possible risk factors and to highlight potential new therapeutic options.

MATERIALS AND METHODS

Allergic contact dermatitis (ACD) as well as the sensitization and trigger phase, potential risk factors as well as the therapy options including (current) PubMed-listed literature are described.

RESULTS

Inflammation plays a central role in ACD. The innate immune system responds to contact allergens as well as to infection. Elucidation of the mechanisms will enable a targeted therapeutic intervention in the future.

CONCLUSION

Although there is still a need for research, many parts of the contact allergy pathogenesis are now better understood. In particular, the essential role of the innate immune response not only for the sensitization but also for the elicitation phase seems to be established. Implementation of today's knowledge into new therapeutic approaches and their application testing remains important and exciting.

Ecotoxicological risk evaluation and regulatory compliance of endocrine disruptor phthalates in a sustainable wastewater treatment scheme

Due to their pervasive applications, phthalic acid esters or phthalates have ample presence in all environmental compartments. A principal source of their existence in freshwater is phthalate-laden wastewater treatment plant effluents. For its sustainable operation and biogas production, wastewater treatment scheme of up flow anaerobic sludge blanket (UASB) and polishing pond is more prevalent in developing countries. This yearlong study focused on evaluating the occurrence, fate and risk of four priority phthalates, diethyl phthalate (DEP), dibutyl phthalate (DBP), benzylbutyl phthalate (BBP), and diethylhexyl phthalate (DEHP) in a UASB+ polishing pond-based wastewater treatment plant. Concentration of the phthalates in raw wastewater ranged from nd to 17.36 μg/L (DEP), 0.92 to 18.26 μg/L (DBP), nd to 6.54 μg/L (BBP), and nd to 53.21 μg/L (DEHP). DEHP concentrations in UASB sludge were below 100 mg/kg, the recommended limit by the European Union for safe disposal of dewatered sludge. All four compounds were removed approximately 80% in the wastewater treatment plant, with larger removal in polishing pond than UASB. Sorption contributes a significant portion of BBP and DEHP removal (15-24%) in UASB than DEP and DBP (0-3%). Seasonally, larger removals of phthalates were observed during the summer season. Risk assessment showed that the treated effluents had low risk of DEP, DBP, and BBP. However, the hazard quotient (HQ) of DEHP was greater than 1. To comply with regulations, dilution requirement of effluents was investigated which showed that a dilution factor of 4.4 in summer and 2.1 in winter is required for effluents of UASB + Pond-based treatment plant.

Bisphenol A and Phthalates Exhibit Similar Toxicogenomics and Health Effects

Bisphenol A and phthalates are most frequently detected organic pollutants found in our surroundings because of their regular use as plasticizers in daily use polymeric products. BPA is used in manufacturing baby feeding bottles, water pipes, canned food linings, and food packaging materials. Phthalates are used in polyvinyl chloride products including clothing, toys, medical devices, and food packaging. These chemicals are not bound to the matrix and leach out into the surroundings on slight change in the environment, like alteration in pH, temperature, and pressure. Humans are continuously exposed to these chemicals through skin contact, inhalation, or ingestion when the leachates enter food, drinks, air, water, or soil. The Comparative Toxicogenomics Database (CTD) revealed that Bisphenol A has 1932 interactions with genes/proteins and few frequently used phthalates (DEHP, MEHP, DBP, BBP, and MBP) showed 484 gene/protein interactions. Similar toxicogenomics and adverse effects of Bisphenol A and phthalates on human health are attributed to their 89 common interacting genes/proteins.

Update of the risk assessment of di-butylphthalate (DBP), butyl-benzyl-phthalate (BBP), bis(2-ethylhexyl)phthalate (DEHP), di-isononylphthalate (DINP) and di-isodecylphthalate (DIDP) for use in food contact materials

The EFSA Panel on Food Contact Materials, Enzymes and Processing Aids (CEP Panel) was asked by the European Commission to update its 2005 risk assessments of di-butylphthalate (DBP), butyl-benzyl-phthalate (BBP), bis(2-ethylhexyl)phthalate (DEHP), di-isononylphthalate (DINP) and di-isodecylphthalate (DIDP), which are authorised for use in plastic food contact material (FCM). Dietary exposure estimates (mean and high (P95)) were obtained by combining literature occurrence data with consumption data from the EFSA Comprehensive Database. The highest exposure was found for DINP, ranging from 0.2 to 4.3 and from 0.4 to 7.0 μg/kg body weight (bw) per day for mean and high consumers, respectively. There was not enough information to draw conclusions on how much migration from plastic FCM contributes to dietary exposure to phthalates. The review of the toxicological data focused mainly on reproductive effects. The CEP Panel derived the same critical effects and individual tolerable daily intakes (TDIs) (mg/kg bw per day) as in 2005 for all the phthalates, i.e. reproductive effects for DBP (0.01), BBP (0.5), DEHP (0.05), and liver effects for DINP and DIDP (0.15 each). Based on a plausible common mechanism (i.e. reduction in fetal testosterone) underlying the reproductive effects of DEHP, DBP and BBP, the Panel considered it appropriate to establish a group-TDI for these phthalates, taking DEHP as index compound as a basis for introducing relative potency factors. The Panel noted that DINP also affected fetal testosterone levels at doses around threefold higher than liver effects and therefore considered it conservative to include it within the group-TDI which was established to be 50 μg/kg bw per day, expressed as DEHP equivalents. The aggregated dietary exposure for DBP, BBP, DEHP and DINP was estimated to be 0.9-7.2 and 1.6-11.7 μg/kg bw per day for mean and high consumers, respectively, thus contributing up to 23% of the group-TDI in the worst-case scenario. For DIDP, not included in the group-TDI, dietary exposure was estimated to be always below 0.1 μg/kg bw per day and therefore far below the TDI of 150 μg/kg bw per day. This assessment covers European consumers of any age, including the most sensitive groups. Based on the limited scope of the mandate and the uncertainties identified, the Panel considered that the current assessment of the five phthalates, individually and collectively, should be on a temporary basis.

Effect of exposure to phthalates on association of polycyclic aromatic hydrocarbons with 8-hydroxy-2'-deoxyguanosine

BACKGROUND

Although polycyclic aromatic hydrocarbons (PAHs) and phthalates separately related to oxidative DNA damage have been reported, the joint effect of them on oxidative DNA damage need to be evaluated.

METHODS

In this pilot study, 106 participants were recruited from the community-dwelling residents (n=1240) of Wuhan city, China. Each individual provided three continuous days of spot urine samples for measuring the urinary monohydroxylated PAHs (OH-PAHs), phthalates metabolites and 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels in the two seasons. Linear mixed effect model and Bayesian Kernel Machine Regression (BKMR) were used to analyze joint effect of urinary PAHs and phthalates metabolites on urinary 8-OHdG levels. We measured cellular and mitochondrial reactive oxygen species (ROS), malondialdehyde (MDA) and glutathione peroxidase (GSH-Px) levels as well as IL-6 and IL-8 secretions by the corresponding commercial kits in HepG2 cells treated with di (2-ethylhexyl) phthalate (DEHP, 62.5, 125.00, 250.00, 500.00 or 1000.00μM) alone, benzo[a]pyrene (BaP, 50.00μM) alone or both DEHP and BaP.

RESULTS

Linear mixed effect model showed that each of urinary PAHs metabolite was positively associated with urinary 8-OHdG levels; urinary level of mono (2-ethylhexyl) phthalate or monoisononyl phthalate was positively associated with urinary 8-OHdG levels; BKMR model indicated that a positive association of eight OH-PAHs with urinary 8-OHdG levels, nine urinary phthalates metabolites enhanced the association. We found that DEHP at the indicated concentration plus 50.00μM BaP increased cellular and mitochondrial ROS levels, IL-6 and IL-8 secretions at 24 and 48h as well as MDA levels and GSH-Px activities at 48h, compared to the solvent control.

CONCLUSIONS

Exposure to certain dose phthalates may attenuate the positive association of PAHs exposure with oxidative DNA damage in the body. DEHP at the certain concentrations enhanced BaP-induced mitochondrial ROS, pro-inflammatory response and the activation of the antioxidant defense system in HepG2 cells.

Dibutyl phthalate-mediated oxidative stress induces splenic injury in mice and the attenuating effects of vitamin E and curcumin

Dibutyl phthalate (DBP) is a ubiquitous environmental contaminant that at certain levels can be harmful to human health. Although DBP has been widely linked to immunotoxicity, any association between DBP exposure and splenic injury remains unknown. The purpose of this study was to investigate whether DBP exposure can induce splenic injury and the antagonistic effects of two antioxidants, vitamin E (VitE) and curcumin (Cur), on DBP-induced splenic injury. The levels of ROS, GSH, T-AOC, IL-1β, TNF-α, cytochrome C, caspase-8, caspase-9 and caspase-3 in the spleen homogenate of mice were measured. Any histopathological changes in the spleen were observed using H&E and toluidine blue staining. And the morphology of mitochondria was observed using Janus Green B staining. The results indicate that exposure to 50 mg/kg DBP could cause histopathological changes of the spleen and result in inflammation and apoptosis associated with oxidative stress, which may lead to splenic injury in mice. Moreover, both VitE and Cur could antagonize the oxidative stress induced by DBP to reduce splenic injury. These findings help to expand our understanding of DBP-mediated immunotoxicity, and to show that VitE and Cur can alleviate DBP-induced splenic injury and the possible DBP-associated decline in immune function.

Degradation of phthalate esters in floor dust at elevated relative humidity

Emerging investigator series: Phthalate esters are present at elevated concentrations in floor dust, and resuspension of dust represents a major source for human exposure to chemicals. Biodegradation of phthalates occurs in aquatic systems and soils but has not been demonstrated in house dust. The goal of this study was to quantify indoor phthalate ester degradation through both biotic and abiotic mechanisms. Worn carpet squares were embedded with dust and incubated for one to six weeks at equilibrium relative humidity (ERH) levels of 50, 80, 85, 90, 95, and 100%, and nine phthalates were measured. Removal was observed for DEHP, BBzP, DINP, DiDP, and DMP (p < 0.05) when incubated under elevated relative humidity conditions. Abiotic and biotic losses were examined separately using dust spiked with deuterated di(2-ethylhexyl)phthalate (d-DEHP) that was embedded in carpet and incubated at 100% ERH. Abiotic processes resulted in a 10.1% (±1.1%, standard error) to 69.6% (±4.8%) decrease in total d-DEHP after one week (p = 0.03) and a 27.2% (±1.4%) to 52.0% (±2.1%) decrease after three weeks (p = 0.008). Biodegradation resulted in a decrease in total d-DEHP after one week, ranging from 5.9% (±8.9%) to 8.5% (±1.7%) (p = 0.07) and a 1.7% (±3.9%) to 10.3% (±4.5%) decrease after three weeks (p = 0.044). Metatranscriptomic-based analysis indicates that fungi found in carpet dust express genes capable of degrading phthalate esters via various biochemical processes (including β-oxidation and hydrolysis). Overall, these results support the hypothesis that phthalate losses in floor dust are due to a combination of abiotic and microbial degradation at ≥80% ERH.

Inhibitions of HMGB1 and TLR4 alleviate DINP-induced asthma in mice

We studied the effects of high mobility group box chromosomal protein 1 (HMGB1) and toll-like receptor (TLR4) in diisonoyl phthalate (DINP)-induced asthma. Mice with DINP-induced asthma were treated with a TLR4-signaling inhibitor or anti-HMGB1 antibody, and various markers of asthma were measured 24 h later. DINP increased airway hyperresponsiveness, numbers of cells in BALF, numbers of inflammatory cells (leukocytes, lymphocytes, monocytes, eosinophils, neutrophils, basophils) in blood, mucus production, pulmonary fibrosis, Th2 type cytokine levels in BALF, and lung cell apoptosis. On the other hand, administrations of TLR4-signaling inhibitors (TAK-242) or anti-HMGB1 antibodies to a mouse model of DINP-induced asthma reduced biological markers of asthma. These results show TLR4 and HMGB1 both contribute to DINP-induced asthma, and that the inhibitions of TLR4 or HMGB1 offer potential means of treating asthma induced by phthalates like DINP.

Bimetallic plasmonic Au@Ag nanocuboids for rapid and sensitive detection of phthalate plasticizers with label-free surface-enhanced Raman spectroscopy

Phthalate plasticizers (PAEs) are posing a serious threat to human health, so it is urgent to develop effective and reliable ways to detect the food additives PAEs sensitively. In this study, we have reported plasmonic bimetallic Au@Ag core-shell nanocuboids for the rapid and sensitive detection of PAEs in liquor samples with a label-free Surface-enhanced Raman Spectroscopy (SERS) strategy. Compared with single-element nanostructures, the bimetallic SERS platform can integrate two distinct functions into a single entity with unprecedented properties. Consequently, we synthesized Au@Ag nanocuboids (Au@Ag NCs) composed of a Au nanorod (Au NR) core and a Ag cuboid shell, which could produce richer and broader plasmonic resonance modes than Au NRs. It is obvious that the SERS signals of crystal violet (CV) and butyl benzyl phthalate (BBP) reached a maximum as the thickness of the Ag coating shell was in a certain threshold and there was a strong dependence of the Raman enhancement on the Ag cuboid shell-thickness. Based on the optimized size, the sensitivity and repeatability of Au@Ag NCs were evaluated with limits of detection (LODs) at around 10^-9 M both for BBP and diethylhexyl phthalate (DEHP). In addition, the SERS active substrate core-shell Au@Ag NCs can be used to detect BBP as low as 1.3 mg kg^-1 spiked into the liquor samples. Thereby, the unique bimetallic Au@Ag NCs showed a huge potential for the rapid and sensitive detection of PAEs in liquor samples.

Systematic review and meta-analysis on the association between phthalates exposure and insulin resistance

This study aims to provide an overview of human studies on the association of exposure to phthalates and insulin resistance. We systematically searched human studies available until 15 January 2018.We conducted a literature search in Scopus, ISI Web of Science, PubMed, Google Scholar, and Cochrane Collaboration. We used the following keywords to identify relevant articles: "phthalate", "phthalate ester", "metabolic syndrome", "insulin resistance", "glucose intolerance", and "diabetes". For analyzing data, we conducted meta-analysis using the Stata software. We appraised each study to examine the sources of heterogeneity, including difference in clinical outcomes and exposure measurements. To determine the robustness and whether some of the factors have the highest impact on the results of the present meta-analysis, several sensitivity analyses were conducted. Sensitivity analysis showed that by removing studies with the highest weight and age groups, no change was observed in heterogeneity. Moreover, with excluding the study conducted in Europe, the results remained unchanged and constant. In addition, the funnel plot and Egger's tests were executed to access publication bias. Both the funnel plots and Egger's test did not show any evidence of publication bias (P = 0.31). In the random effects meta-analysis of all studies (n = 8), the pooled correlation coefficient between phthalate exposure and HOMA-IR was 0.10 (95% CI; 0.07-0.12, P < 0.001), with significant heterogeneity (P < 0.001, I² = 85.5%). Our findings revealed positive association between exposure to phthalate metabolites and increased HOMA-IR; this association remained significant even after adjusting the analysis for multiple confounding variables.

Modulation of heat-shock response is associated with Di (2-ethylhexyl) phthalate (DEHP)-induced cardiotoxicity in quail (Coturnix japonica)

Di(2-ethylhexyl) phthalate (DEHP) is an omnipresent environmental pollutant with endocrine disrupting properties. As a plasticizer, DEHP can be leach from the plastic to transfer the external environment and thus enters the animal food chain, causing serious damage to the animal organs. The heat-shock response (HSR) comprising heat-shock protein (HSPs) and heat-shock transcription factor (HSFs) plays a pivotal role in various toxic stress conditions. For the sake of investigating the effects of DEHP exposure on cardiac toxicity and the regulation of HSR, male quail were fed the diet with 0, 250, 500 and 750 mg/kg DEHP by gavage administration for 45 days. Histopathological changes including cardiomyocyte swelling and muscle fiber dilatation were observed in the hearts exposed to DEHP. During the DEHP treatment, the mRNA expression of HSP60 and HSP70 were universally reduced, while the expression of other HSPs (HSP10, HSP25, HSP27, HSP40, HSP47, HSP90, HSP110) had different degrees of growth. In addition, the levels of HSF1, HSF2, and HSF3 were significantly increased. Given the facts above, DEHP exposure induced the toxic effects of quail heart. DEHP exposure did great harm to HSR via affecting the synthesis of HSFs to mediate the transcription of the HSPs. Ultimately, this study provided new evidence that DEHP-induced cardiotoxicity in quail was related to activation of HSR and playing a protective role.

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.

Endocrine disruptor responses in African sharptooth catfish (Clarias gariepinus) exposed to di-(2-ethylhexyl)-phthalate

In the present study, we have investigated the endocrine disruptive effects of waterborne di-(2-ethylhexyl) phthalate (DEHP: 0 (control), 10, 100, 200 and 400 μg/L) on juvenile Clarias gariepinus by analyzing transcript patterns for hepatic vitellogenin (vtg), estrogen receptor-α (er-α), aromatase (cyp19a1b) and peroxisome proliferator activated receptor-α (ppar-α) using quantitative real-time PCR after 3, 7 and 14 days exposure period. In addition, we analyzed CYP19 and PPAR protein levels using enzyme-linked immunosorbent assay (ELISA), while cellular testosterone (T) and 17β-estradiol (E2) levels were measured using enzyme immune assay (EIA). Tissue burden of DEHP was measured in the liver using gas chromatography-mass spectroscopy (GC-MS). We observed apparent concentration- and time-dependent increases of vtg, er-α, cyp19a1b transcripts, E2 and T levels after exposure to DEHP. A biphasic pattern of effect was observed for ppar-α, showing a concentration-dependent increase that peaked at 100 μg/L and thereafter, an apparent concentration-dependent decrease at 200 and 400 μg/L at all exposure days. Given that the post-differentiation changes of gonads in C. gariepinus corresponded with the 14-day sampling period, we separated the analyzed data into sexes after histological examination of the gonads, showing that females responded stronger, compared to males, to DEHP exposure at all exposure concentrations. Oocyte atresia, intersex (ovotestis) and karyoplasmic clumping were observed in females while male fish showed distortion and degeneration of seminiferous tubules and condensation of tubular cells in the 400 μg/L exposure group after 14 days. Corresponding canonical analysis (CCA) of all analyzed variables revealed a positive relationship between analyzed biological variables with increasing DEHP concentrations. Overall, molecular, biochemical and physiological responses presented in the present study indicate that exposure of C. gariepinus to waterborne DEHP produced endocrine disruptive responses with potential consequences for overt reproduction, development, physiology and general health of fish populations inhabiting phthalate contaminated aquatic environments. These responses represent valuable and effective biomarkers of exposure and effects, that can be adopted for screening the presence of EDCs in Nigeria and other developing countries.

Disruption of the gonadal endocannabinoid system in zebrafish exposed to diisononyl phthalate

DiNP (Di-isononyl phthalate) has been recently introduced as DEHP (Bis (2-ethylhexyl) phthalate) substitute and due to its chemical properties, DiNP is commonly used in a large variety of plastic items. The endocannabinoid system (ECS) is a lipid signaling system involved in a plethora of physiological pathways including the control of the reproductive and metabolic processes. In this study, the effects of DiNP on the ECS of zebrafish (male and female) gonads were analyzed. Adult zebrafish were chronically exposed for 21 days via water to 3 environmentally relevant concentrations of DiNP (42 μg/L; 4.2 μg/L; 0.42 μg/L). In females, the Gonadosomatic Index (GSI) and the number of fertilized eggs were reduced by the lowest concentration of DiNP tested. The levels of two endocannabinoids, Anandamide (AEA) and 2-Arachidonoylglycerol (2-AG), were not affected, while a reduction of the N-oleoyl-ethanolamine (OEA) level was observed. Transcriptional changes were reported in relation to genes coding for the ECS receptors and the enzymes involved in the ECS pathway. DiNP exposure in males reduced the GSI as well as changed the levels of endocannabinoids. Moreover, DiNP treatment induced significative changes in the genes coding for the ECS receptors and enzymes, and significantly increased the activity of the fatty acid amide hydrolase (FAAH). In summary, in zebrafish, exposure to environmentally relevant concentrations of DiNP disrupted the ECS and affected reproduction in a gender specific manner.

New insights into the mechanism of phthalate-induced developmental effects

To investigate the biological pathways involved in phthalate-induced developmental effects, zebrafish embryos were exposed to different concentrations of di-(2-ethylhexyl) (DEHP) and di-butyl phthalate (DBP) for 96 h. Embryonic exposure to DEHP and DBP induced body length decrease, yolk sac abnormities, and immune responses (up-regulation of immune proteins and genes). The lipidomic results showed that at a concentration of 50 μg/L, DEHP and DBP significantly reduced the levels of fatty acids, triglycerides, diacylglycerol, and cholesterol. These effects are partly explained by biological pathway enrichment based on data from the transcriptional and proteomic profiles. Co-exposure to DBP and ER antagonist did not significantly relieve the toxic symptoms compared with exposure to DBP alone. This indicates that phthalate-induced developmental abnormities in zebrafish might not be mediated by the ER pathway. In conclusion, we identified the possible biological pathways that mediate phthalate-induced developmental effects and found that these effects may not be driven by estrogenic activation.

Extraneous dissolved organic matter enhanced adsorption of dibutyl phthalate in soils: Insights from kinetics and isotherms

The widespread use of plastic film, especially in agricultural practices, has resulted in phthalic acid esters (PAEs) pollution, which poses risks for greenhouse soils. Application of composted manure is a common agricultural practice that adds extraneous dissolved organic matter (DOM) to the soil, however, the effect of extraneous DOM on the behavior of PAEs in agricultural soil is not clear. Dibutyl phthalate (DBP) was used as a model compound to investigate the effect and mechanism of extraneous DOM on the adsorption kinetics and isotherms of PAEs in two types of soils, through batch experiments and characterization of extraneous DOM and soils using fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). The equilibrium adsorption amount of DBP in black soil was higher than in red soil regardless of the presence of extraneous DOM, due to the higher organic matter content of black soil. Hydrophobic partition played a dominant role in the DBP adsorption process of soils with and without extraneous DOM. The addition of DOM enhanced the adsorption capacity of DBP through partition in the two soils, especially at high DBP concentrations. Additions of a lower concentration of DOM better enhanced the adsorption effect than the higher concentrated DOM, due to an increase in water solubility of DBP resulted from excessive extraneous DOM in aqueous phase. Differences in mineral composition of soils led to diverse adsorption mechanisms of DBP as affected by additions of extraneous DOM. The FTIR spectra indicated that the intra-molecular and intermolecular hydrogen bond interactions of carboxylic acids, aromatic CC and CO in amides were involved in DBP adsorption in soils. Therefore, addition of DOM may increase adsorption of DBP in soils and thus influence its bioavailability and transformation in soils.

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.

Distribution of phthalates in Marseille Bay (NW Mediterranean Sea)

Phthalic Acid Esters (PAEs) are a group of emerging organic contaminants that have become a serious issue because of their ubiquitous presence and hazardous impact on the marine environment worldwide. Seawater samples were collected monthly from December 2013 to November 2014 in the northwestern Mediterranean Sea (Marseille Bay). The samples were analyzed for dissolved organic carbon (DOC) as well as the molecular distribution of dissolved PAEs by using solid phase extraction followed by gas chromatography and mass spectrometry (GC/MS) analyses. The results demonstrated the occurrence of six PAEs, including dimethyl phthalate (DMP), diethyl phthalate (DEP), di-isobutyl phthalate (DiBP), di-n-butyl phthalate (DnBP), benzylbutyl phthalate (BzBP) and diethylhexyl phthalate (DEHP), with total concentrations ranging from 130 to 1330ngL^-1 (av. 522ngL^-1). In Marseille Bay, the highest concentrations were detected in the bottom water from June to November 2014 and in the whole water column during the winter mixing period. This result suggests that resuspension of PAE-rich sediment, in relation to the accumulation of plastic debris above the seabed, or the higher degradation rate in the upper layer of the water column, plays a significant role in the PAE dynamics in coastal water. DEHP was the most abundant PAE in all of the surface samples and the summer bottom samples, followed by DiBP and DnBP, which also represent the largest fractions in the other bottom samples.

Current State, Distribution, and Sources of Phthalate Esters and Organophosphate Esters in Soils of the Three Gorges Reservoir Region, China

Phthalate esters (PAEs) and organophosphate esters (OPEs) were identified and quantified in surface soils from farmland and riparian areas of the Three Gorges Reservoir (TGR), western China. Generally, the mean values of PAEs and OPEs were 618 and 266 ng/g dry weight (dw) in farmland soil and 560 and 499 ng/g dw in riparian soil, respectively. The occurrence of OPEs should be regarded as a risk factor in the TGR region. Analogous spatial distribution patterns for PAEs were observed with higher concentrations observed at site WZ in both types of soil, which might relate to the anthropogenic activities. The hydrodynamic conditions might be important factors contributing to the slightly different spatial distribution of OPEs. The concentrations of OPEs in riparian soil exceed those in farmland soil at all sampling sites, which could partly be ascribed to the complete operation of the TGR. Dibutyl phthalate (DnBP) was the most dominated PAEs congener in both types of soil. Of particular note is the elevated contribution of tris(methylphenyl) phosphate (TMPP), followed by 2-ethylhexyl diphenyl phosphate (EHDPP), accounting for more than 90% of the total OPEs, and the shipping or/and the local human activity might be considered as the major contributor. The slight differences in PAEs composition of principal components might largely attribute to the variety of emission sources in two types of soil. The different cluster patterns between two types of soil indicated that the anthropogenic activities as well as the full operation of TGR, may play a role.

Endotoxin enhances respiratory effects of phthalates in adults: Results from NHANES 2005-6

Phthalates have been associated with respiratory symptoms in adults; they may enhance effects of inflammatory compounds. To assess the potential interactions of phthalates and endotoxin on respiratory and allergic symptoms in adults, we used cross-sectional information from the 1091 adults with complete data on urinary phthalates and house dust endotoxin from NHANES 2005-2006. We used multivariable logistic regression to assess whether endotoxin levels modified the association between nine phthalate metabolites and four current allergic symptoms (asthma, wheeze, hay fever, and rhinitis). Endotoxin was classified into tertiles (<10, 10-25, >25EU/mg dust). Urinary phthalate and dust endotoxin levels were not correlated (r < |0.02|). Under low endotoxin conditions, no associations between phthalates and respiratory outcomes were observed. Under medium or high endotoxin conditions, exposure-response relationships were observed between specific phthalates and wheeze and asthma. For wheeze, three phthalates (mono-benzyl phthalate (MBzP), mono(carboxyoctyl) phthalate (MCOP), and di-ethylhexyl phthalate (DEHP) had significant interactions with endotoxin); for asthma, two phthalates (MCOP and mono(carboxyoctyl) phthalate (MCNP)) had significant interactions. Endotoxin did not modify the associations between phthalates and hay fever or rhinitis. These results are consistent with the hypothesis that endotoxin enhances the respiratory toxicity of phthalates; however this cross-sectional study cannot address key temporal issues. The lack of an association between wheeze or asthma and phthalates when endotoxin exposure was low suggests that phthalates alone may not increase these symptoms.

Effects of prenatal di(2-ethylhexyl) phthalate exposure on childhood allergies and infectious diseases: The Hokkaido Study on Environment and Children's Health

Phthalates are widely used in consumer products, and experimental studies suggest that exposure to phthalates increase the risk of allergies. However, epidemiologic evidence on the associations between prenatal phthalate exposure and allergies/infectious diseases and cord blood immunoglobulin E (IgE) levels is limited. This study aimed to evaluate the associations between maternal mono(2-ethylhexyl) phthalate (MEHP) levels and cord blood IgE levels at birth (n=127), as well as the risk of allergies/infectious diseases in participants up to 7years of age; the participants were 1.5 (n=248), 3.5 (n=222), 7 (n=184) years of age. Maternal blood MEHP level in the second trimester was measured using gas chromatography-mass spectrometry. Participant characteristics were obtained from the medical birth records and self-administered questionnaires during pregnancy and after delivery. Wheeze and eczema were defined according to the Japanese version of the International Study of Asthma and Allergies in Childhood and the American Thoracic Society-Division of Lung Diseases questionnaire, respectively. Infectious diseases were defined using questionnaires for each specified age. To evaluate the associations between maternal MEHP and allergies or infectious diseases, we used logistic regression analysis and generalized estimating equations analysis. Maternal MEHP levels were negatively associated with cord blood IgE levels and increased risks of allergies and infectious diseases up to 7years of age. This is the first study to investigate the effects of prenatal MEHP exposure on IgE levels at birth and allergies/infectious diseases up to 7years of age. Further epidemiological studies should focus on other phthalate metabolites and their health effects on larger populations.

Diisononyl phthalate aggravates allergic dermatitis by activation of NF-kB

Several epidemiological studies have suggested a possible link between exposure to Diisononyl phthalate (DINP) and the development of allergies. These findings remain controversial since there is insufficient scientific evidence to assess the ability of DINP to influence allergic immune responses. In addition, the mechanisms behind DINP-caused allergic diseases have not been fully elucidated. In this study, Balb/c mice were orally exposed to DINP for 3 weeks and were then sensitized with fluorescein isothiocyanate (FITC). We showed that oral exposure to DINP could aggravate allergic-dermatitis-like lesions, indicated by an increase in the number of mast cells, and in increased skin edema in FITC-induced contact hypersensitivity. This deterioration was concomitant with increased total serum immunoglobulin-E and Th2 cytokines. We determined the oxidative damage and the activation of nuclear factor-kb (NF-kB). The data demonstrated that DINP could promote oxidative damage and the activation of NF-kB in the skin. The expression of thymic stromal lymphopoietin and the activation of signal transducer and activator of transcriptions 3, 5 and 6 were enhanced concomitant with exacerbated allergic dermatitis effects and the activation of NF-kB induced by DINP. These effects were alleviated by pyrollidine dithiocarbamate, an inhibitor of NF-kB. The results suggest that oral exposure to DINP aggravated allergic contact dermatitis, which was positively regulated via NF-kB.

Childhood exposure to phthalates and pulmonary function

Phthalate exposure is related to the development of allergic diseases; however, studies regarding its effect on lung function are limited. Our study aims to identify an association between phthalate exposure at different ages and lung function in children at age 9 by conducting a cohort study. The Taiwan Birth Panel Study (TBPS) was established from April 2004 to January 2005. Urine samples were collected from children in the TBPS cohort at ages 2, 5, and 9years. Urinary phthalate metabolite concentrations were measured via ultrahigh-performance liquid chromatography coupled with tandem mass spectrometry. Questionnaires, lung function tests and serum IgE levels were obtained from children at the age of 9. Multiple linear regressions adjusted for confounding factors were applied to investigate the associations between phthalate exposure at different ages and lung function at age 9. Our results demonstrate that in children with allergic diseases, a per log unit increase in the urinary phthalate metabolite mono-ethyl phthalate (MEP) concentration at age 9 was associated with a decreasing forced expiratory volume in 1 sec (FEV1) (β=-25.22; 95% CI: -47.53 to -2.91 per log ml/ln-μg/g cr) and forced vital capacity (FVC) (β=-32.3; 95% CI: -63.51 to -1.09 per log ml/ln-μg/g cr). For children with high serum IgE levels (>100kU/L) at age 9, the urinary MEP concentrations at the same age were negatively associated with the FEV1 (β=-30.4; 95% CI: -56.8 to -4.0 per log ml/ln-μg/g cr), FVC (β=-47.6; 95% CI: -84.2 to -11.0 per log ml/ln-μg/g cr) and peak expiratory flow (PEF) (β=-102.4; 95% CI: 180.2 to -24.7 per log ml/ln-μg/g cr). Phthalate exposure at ages 2 and 5 had little effect on lung function at age 9. Our study suggests that concurrent exposure to phthalates, such as MEP, is negatively associated with lung function in children. Further investigation is required to elaborate on this correlation.

Exposure to diisodecyl phthalate exacerbated Th2 and Th17-mediated asthma through aggravating oxidative stress and the activation of p38 MAPK

Diisodecyl phthalate (DIDP) is considered to be one of the less toxic phthalates. However epidemiological studies suggest that DIDP is associated with the occurrence of asthma. The effect of DIDP exposure on allergic asthma and the underlying mechanism have not been fully elucidated. Here, mice were exposed to DIDP and sensitization with OVA. The results demonstrated that DIDP exposure aggravated allergic asthma. Exposure to 15 mg/kg/day DIDP markedly exacerbated airway remodeling and promoted airway hyperresponsiveness (AhR). The study suggests that exposure to DIDP not only promotes a predominant Th2 response, but also induces Th17-type immunity. The induced allergic asthma was accompanied by elevation of IgE, an increase in TSLP expression and exacerbation of oxidative stress. Inhibition of oxidative stress by Vitamin E effectively alleviated the airway remodeling and AhR induced by DIDP and OVA sensitization. Treatment with Vitamin E inhibited the Th2 response and the production of TSLP. Blocking the activation of p38 MAPK by SB203580 prevented elevation of IL-1β and IL-17A induced by DIDP and OVA sensitization and effectively alleviated Th17 type asthmatic lesions. These results suggest that exposure to DIDP exacerbates the Th2 and Th17 response through aggravating oxidative stress and activation of the p38 MAPK pathway.

Latent class analysis to model multiple chemical exposures among children

BACKGROUND

Children are exposed to multiple potentially harmful chemicals simultaneously. Efforts to understand the patterns and consequences of these exposures have been hampered by statistical limitations in estimations of higher order interactions.

OBJECTIVES

The current study uses latent class analysis, a form of person-centered modeling to identify unobservable subgroups within populations and examine relationships between latent classes and measures of immune function.

METHODS

Data from the National Health and Nutrition Examination Survey 2011-2012 were analyzed. A sample of 721 children aged 6-19 years were included who provided data on 47 chemicals of interest representing six chemical classes. Groups were identified using latent class analysis controlling for race/ethnicity, age, sex and poverty status.

RESULTS

Two alternative approaches to identifying latent classes each resulted in similar three class solutions, including one group of children characterized by low co-exposures across chemicals, a group with moderate co-exposure levels, and a group characterized by high co-occurring levels of polycyclic aromatic hydrocarbons, volatile organic compounds, phenols and phthalates. Under one of the approaches, latent classes were significantly associated with immune function as measured by lymphocyte and neutrophil counts.

CONCLUSIONS

Latent class analysis offers a potential approach to measuring and understanding interactions among multiple co-occurring chemical stressors. However, additional work is needed to test the ability of latent classes to predict health variables.

Pathomechanisms of Contact Sensitization

Contact sensitization is the initial process involved in the development of an allergic reaction to xenobiotic environmental substances. Here, we briefly describe the differences between irritant and allergic contact dermatitis. Then, we highlight the essential steps involved in the development of an ACD reaction, i.e., the protein binding of haptens, genetic factors influencing the penetration of sensitizers into the skin, the different mechanisms driving the initial development of an inflammatory cytokine micromilieu enabling the full maturation of dendritic cells, the role of pre- and pro-haptens, antigen presentation and T cell activation via MHC and CD1 molecules, dendritic cell (DC) migration, and potential LC contribution as well as the different T cell subsets involved in ACD. In addition, we discuss the latest publications regarding factors that might influence the sensitizing potential such as repeated sensitizer application, penetration enhancers, humidity of the skin, microbiota, Tregs, and phthalates. Last but not least, we briefly touch upon novel targets for drug development that might serve as treatment options for ACD.

Phthalates impact human health: Epidemiological evidences and plausible mechanism of action

Disregarding the rising alarm on the hazardous nature of various phthalates and their metabolites, ruthless usage of phthalates as plasticizer in plastics and as additives in innumerable consumer products continues due low their cost, attractive properties, and lack of suitable alternatives. Globally, in silico computational, in vitro mechanistic, in vivo preclinical and limited clinical or epidemiological human studies showed that over a dozen phthalates and their metabolites ingested passively by man from the general environment, foods, drinks, breathing air, and routine household products cause various dysfunctions. Thus, this review addresses the health hazards posed by phthalates on children and adolescents, epigenetic modulation, reproductive toxicity in women and men; insulin resistance and type II diabetes; overweight and obesity, skeletal anomalies, allergy and asthma, cancer, etc., coupled with the description of major phthalates and their general uses, phthalate exposure routes, biomonitoring and risk assessment, special account on endocrine disruption; and finally, a plausible molecular cross-talk with a unique mechanism of action. This clinically focused comprehensive review on the hazards of phthalates would benefit the general population, academia, scientists, clinicians, environmentalists, and law or policy makers to decide upon whether usage of phthalates to be continued swiftly without sufficient deceleration or regulated by law or to be phased out from earth forever.

Phthalate esters and childhood asthma: A systematic review and congener-specific meta-analysis

INTRODUCTION

Exposure to phthalate esters (PAEs) has been associated with childhood asthma, but the congener-specific effects of PAEs on childhood asthma were unclear. We aimed to systematically review and meta-analyze observational studies on the associations between specific effects of PAEs and the risk of childhood asthma.

MATERIAL AND METHODS

Relevant studies were identified by searching three databases up to October 20, 2016. The reference lists of the retrieved articles were also reviewed. We included observational studies that reported risk estimates with 95% confidence intervals (CIs) for the associations between phthalate exposure and the risk of childhood asthma. Fixed-effects models were generally applied to calculate pooled risk estimates. When heterogeneity was present, random-effects models were applied.

RESULTS

A total of nine studies featuring 43 data points were included in our final meta-analyses. Results indicated that the benzyl butyl phthalate (BBzP) exposure had a significant association with the risk of childhood asthma. The Odd Ratios (ORs) were from 1.39 to 1.41 for different combination strategies. Subgroup analyses by different exposure period or samples used showed that prenatal exposure to BBzP had a stronger association with the risk of childhood asthma (OR = 1.38, 95% CI = 1.09-1.75), compared to those with postnatal exposure. Besides, the association was evident when the phthalate exposure was measured from dust samples. The OR for the associations between di-2-ethylhexyl phthalate (DEHP) in dust and childhood asthma was 2.71 (95% CI = 1.39-5.28), and 2.08 (95% CI = 1.10-3.92) for BBzP.

CONCLUSIONS

Our study suggested a positive association between DEHP and BBzP exposure and childhood asthma. Future studies are warranted to identify the underlying mechanisms of the association.

TRPA1 mediated aggravation of allergic contact dermatitis induced by DINP and regulated by NF-κB activation

The possible pathogenic role and mechanism of Di-iso-nonyl phthalate (DINP) in allergic dermatitis is still controversial. This work has shown that oral exposure to DINP exacerbated allergic dermatitis tissue lesions in FITC-sensitized mice. The lesions was accompanied by an enhancement of TRPA1 expression and an increase in IgG1, IL-6 and IL-13 levels. This work also found that blocking TRPA1 by HC030031 effectively prevented the development of allergic dermatitis resulting from oral exposure to DINP and/or FITC-sensitized mice. This result is marked by the down regulation of IgG1 levels, a reduction in mast cell degranulation and a decrease in IL-6 and IL-13 levels. We also showed that blocking NF-κB inhibited TRPA1 expression, and that blocking TRPA1 had no significant effect on the activation of NF-κB or TSLP expression. This study helps in understanding the role DINP exposure plays in the development of allergic dermatitis and provides new insight into the mechanisms behind the DINP-induced adjuvant effect.

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

BACKGROUND

In Belgium, around 8.5% of the children have asthmatic symptoms. Increased asthma risk in children has been reported in relation to exposure to phthalate plasticizers but the underlying mechanisms are largely unknown.

AIM

The aim of this study was to identify if oxidative stress, assessed by excision of 8-hydroxydeoxyguanosine (8-OHdG) from damaged DNA, is an intermediate marker for the association between phthalate exposure and doctor-diagnosed asthma.

MATERIAL AND METHODS

In 418 14-15-year-old youngsters, recruited as a representative sample of residents of Flanders (Belgium), personal exposure to phthalates was assessed by measuring phthalate metabolites in urine: mono(2-ethylhexyl) phthalate (MEHP), mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono(2-ethyl-5-oxohexyl) phthalate (MEOHP), mono-n-butyl phthalate (MnBP), mono-benzyl phthalate (MBzP), mono-isobutyl phthalate (MiBP) and mono-ethyl phthalate (MEP). Analysis of 8-OHdG in urine was used as a sensitive biomarker of oxidative stress at the level of DNA. The presence of doctor-diagnosed asthma was elicited by a self-administered questionnaire. Associations were assessed using multiple linear and logistic regression models. Mediation was tested using Baron and Kenny's regression approach.

RESULTS

A significant increased risk of a youngster being diagnosed with asthma was found for both urinary MnBP (metabolite of dibutyl phthalate (DBP)) and the sum of the three di(2-ethylhexyl) phthalate metabolites (ΣDEHP=MEHP+MEHHP+MEOHP), with respective odds ratio of 1.84 [95% CI: 1.02, 3.32] for MnBP and 1.94 [95% CI: 1.07, 3.51] for ΣDEHP. In addition, we observed significant associations between all urinary phthalate metabolites and increased urinary levels of 8-OHdG. The associations were stronger in girls than in boys. We did not found evidence that 8-OHdG was associated with doctor-diagnosed asthma.

CONCLUSION

The results of our study are in line with other findings from epidemiological surveys and raise further concern about DEHP and DBP as risk factors for asthma, however, the underlying mechanisms are not yet well understood.

Comparative study of hydrolytic metabolism of dimethyl phthalate, dibutyl phthalate and di(2-ethylhexyl) phthalate by microsomes of various rat tissues

Phthalates are used in food packaging, and are transferred to foods as contaminants. In this study, we examined the hydrolytic metabolism of dimethyl phthalate (DMP), dibutyl phthalate (DBP) and di(2-ethylhexyl) phthalate (DEHP) by rat tissue microsomes. We found that carboxylesterase and lipase contribute differently to these activities. When DMP, DBP and DEHP were incubated with rat liver microsomes, DBP was most effectively hydrolyzed to the phthalate monoester, followed by DMP, and the activity toward DEHP was marginal. In contrast, small-intestinal microsomes exhibited relatively higher activity toward long-side-chain phthalates. Pancreatic microsomes showed high activity toward DEHP and DBP. Liver microsomal hydrolase activity toward DMP was markedly inhibited by bis(4-nitrophenyl)phosphate, and could be extracted with Triton X-100. The activity toward DBP and DEHP was partly inhibited by carboxylesterase inhibitor, and was partly solubilized with Triton X-100. Ces1e, Ces1d and Ces1f expressed in COS cells exhibited the highest hydrolase activity toward DBP, showing a similar pattern to that of liver microsomes. Ces1e showed activity towards DMP and DEHP. Pancreatic lipase also hydrolyzed DBP and DEHP. Thus, carboxylesterase and lipase contribute differently to phthalate hydrolysis: short-side-chain phthalates are mainly hydrolyzed by carboxylesterase and long-side-chain phthalates are mainly hydrolyzed by lipase.

A systematic review on the adverse health effects of di-2-ethylhexyl phthalate

Di (ethylhexyl) phthalate (DEHP) is a global environmental pollutant. This study aims to systematically review the literature on health effects of exposure to DEHP including effects on reproductive health, carcinogenesis, pregnancy outcome, and respiratory system. The literature search was done through Scopus, ISI Web of Science, Google Scholar, PubMed, Medline, and the reference lists of previous review articles to identify relevant articles published to June 2016 in each subject area. The inclusion criteria were as follows: original research, cross-sectional studies, case-control studies, cohort studies, interventional studies, and review articles. Both human and animal studies were included. The search was limited to English language papers. Conference papers, editorials, and letters were not included. The systematic review was conducted and reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Overall, 152 of the 407 papers met the inclusion criteria. We provided an up-to-date comprehensive and critical assessment of both human and animal studies undertaken to explore the effects of DEHP. It revealed that in experimental studies, exposure to DEHP mainly targeted the reproductive, neurodevelopment, and respiratory systems. Human studies reported that exposure to this contaminant had carcinogenic effects and influenced neurodevelopment in early life. This systematic review underscored the adverse health effects of DEHP for pregnant women and the pediatric age group. It summarizes different response of humans and experimental animals to DEHP exposure, and some suggested underlying mechanisms.

Tissue Phthalate Levels Correlate With Changes in Immune Gene Expression in a Population of Juvenile Wild Salmon

Phthalates have detrimental effects on health and have been shown to dysregulate the immune system of mammals, birds, and fish. We recently reported that di(2-ethylhexyl) phthalate exposure reduces the abundance and inhibits the proliferation of rainbow trout (Oncorhynchus mykiss) IgM(+) B lymphocytes and expression of secreted immunoglobulin heavy-chain mu transcripts in an in vitro culture system. We proposed that phthalates act as immunomodulators by modifying the normal B cell-activation pathways by accelerating B cell differentiation while suppressing plasmablast expansion, thus resulting in fewer IgM-secreting plasma cells. This hypothesis was tested here in an in vivo field study of juvenile Dolly Varden (Salvelinus malma) from a plastic-polluted lake in the Gulf of Alaska. Fish tissues were analyzed for both phthalate levels using liquid chromatography-coupled tandem mass spectrometry and for changes in immune gene expression using reverse transcriptase-real time polymerase chain reaction. Results showed that fish with higher tissue levels of di(2-ethylhexyl) phthalate, di(n-butyl) phthalate, and/or dimethyl phthalate expressed significantly fewer secreted and membrane-bound immunoglobulin heavy-chain mu and Blimp1 transcripts in their hematopoietic tissue. This suggests that in vivo uptake of phthalates in fish changes the expression of B cell-specific genes. Chronic exposure to phthalates likely dysregulates normal B-lymphoid development and antibody responses in salmonids and may increase susceptibility to infection. Given the conserved nature of B-lineage cells in vertebrate animals, other marine species may be similarly affected by chronic phthalate exposure.