Reproductive and developmental toxicity of phthalates

Association between phthalate exposure and insulin resistance: a systematic review and meta-analysis update

An update on systematic review and meta-analysis was performed to explore effects of phthalate exposure on insulin resistance. A systematic literature search was performed in MEDLINE, Web of Science, and CNKI until March 2021. A conceptual framework was constructed to guide the organization and presentation of results. Besides, beta coefficients with corresponding confidence intervals were extracted from the most adjusted models. Extracted beta coefficients were transformed into correlation, and z Fisher transformation of correlation with the corresponding standard error was included in meta-analysis. Subgroup analyses were performed by age (adult vs. adolescent) and sex (female vs. male) of participants and site of study (America and Europe vs. Asia) to explore potential sources of heterogeneity. Nineteen literatures with 12,533 participants reporting on the association of exposure to specific phthalates and insulin resistance were selected. The majority of included studies revealed positive relationships of insulin resistance with different phthalate metabolites exposure. Meta-analyses were performed on 16 studies. Exposure to MnBP, MBzP, MCPP, MEHP, MEOHP, MEHHP, ∑DEHP, and high-molecular weight phthalate (∑HMWP) was associated with the increase of the homeostasis model assessment of insulin resistance (HOMA-IR) index. The results of sensitivity analyses stratified by age, sex, and site of study remained stable, suggesting the robustness of these meta-analyses. Most of heterogeneity in sensitivity analyses decreased to moderate or low degree. Exposure to MnBP, MBzP, MCPP, MEHP, MEOHP, MEHHP, ∑DEHP, and ∑HMWP was associated with the increased risk of HOMA-IR. Age, sex, and site of study might provide limited source of heterogeneity.

The effects of phthalate ester exposure on human health: A review

Phthalate esters (PAEs) are one of the most widely used plasticizers in polymer products and humans are increasingly exposed to them. The constant exposure to PAEs-contained products has raised some concerns against human health. Thus, the impacts of PAEs and their metabolites on human health require a comprehensive study for a better understanding of the associated risks. Here, we attempt to review eight main health effects of PAE exposure according to the most up-to-date studies. We found that epidemiological studies demonstrated a consistent association between PAE exposure (especially DEHP and its metabolites) and a decrease in sperm quality in males and symptom development of ADHD in children. Overall, we found insufficient evidence and lack of consistency of the association between PAE exposure and cardiovascular diseases (hypertension, atherosclerosis, and CHD), thyroid diseases, respiratory diseases, diabetes, obesity, kidney diseases, intelligence performance in children, and other reproductive system-related diseases (anogenital distance, girl precocious puberty, and endometriosis). Future studies (longitudinal and follow-up investigations) need to thoroughly perform in large-scale populations to yield more consistent and powerful results and increase the precision of the association as well as enhance the overall understanding of potential human health risks of PAEs in long-term exposure.

Data Mining Approaches for Assessing Chemical Coexposures Using Consumer Product Purchase Data

The use of consumer products presents a potential for chemical exposures to humans. Toxicity testing and exposure models are routinely employed to estimate risks from their use; however, a key challenge is the sparseness of information concerning who uses products and which products are used contemporaneously. Our goal was to demonstrate a method to infer use patterns by way of purchase data. We examined purchase patterns for three types of personal care products (cosmetics, hair care, and skin care) and two household care products (household cleaners and laundry supplies) using data from 60,000 households collected over a one-year period in 2012. The market basket analysis methodology frequent itemset mining (FIM) was used to identify co-occurring sets of product purchases for all households and demographic groups based on income, education, race/ethnicity, and family composition. Our methodology captured robust co-occurrence patterns for personal and household products, globally and for different demographic groups. FIM identified cosmetic co-occurrence patterns captured in prior surveys of cosmetic use, as well as a trend of increased diversity of cosmetic purchases as children mature to teenage years. We propose that consumer product purchase data can be mined to inform person-oriented use patterns for high-throughput chemical screening applications, for aggregate and combined chemical risk evaluations.

Prevalence of phthalate alternatives and monoesters alongside traditional phthalates in indoor dust from a typical e-waste recycling area: Source elucidation and co-exposure risk

This study first discovered the prevalence of phthalate (PAE) alternatives and PAE monoesters alongside traditional PAEs with elevated concentrations in indoor dust from typical e-waste recycling industrial park and adjacent communities. Among nine PAEs, high-molecular-weight (HMW) PAEs dominated over low-molecular-weight (LMW) PAEs in e-waste dust, with total concentrations (∑₉PAEs) ranging from 170 to 5300 μg g^-1. The diisononyl phthalate (DiNP) was identified as the most abundant PAE in e-waste dust, with over 10 times higher median concentration than that measured in home dust. Total concentrations of three PAE alternatives ranged from 20 to 1600 μg g^-1 in e-waste dust, which were 3-10 times higher than the measured levels in home dust. A total of 13 monoesters were all identified in all samples with total concentrations of 4.7-59 μg g^-1, and biodegradation of diesters was recognized as the major source of monoesters present in indoor dust. Significant correlations between the concentrations of PAE alternatives and the HMW PAEs were observed (p < 0.05), indicating that they are being simultaneously used in electronic and electrical products. The occupationally high co-exposure of e-waste dismantling workers to multiple PAEs and PAE alternatives as well as their monoesters should be of concern.

Multiple bioanalytical methods reveal a thyroid-disrupting mechanism related to the membrane receptor integrin αvβ3

Di(2-ethylhexyl) phthalate (DEHP), a manufactured chemical, is suitable for large-scale production and has extensive applications. Although restricted for use, DEHP is still ubiquitous in the environment and shows potential to disrupt the structure or function of the thyroid system. However, its toxic mechanism is complex and not clearly understood. In this study, a battery of methods was employed to investigate DEHP-induced thyroid-disrupting effects and their mechanism of action, focusing on a newly discovered membrane receptor-mediated mechanism. The results showed that DEHP promoted rat pituitary tumor (GH3) cell proliferation and c-fos gene expression at environment level concentrations (2 and 5 μmol/L) in a manner similar to that of the natural thyroid hormone 3,3',5-triiodo-L-thyronine (T3). The macromolecule DEHP-BSA cannot pass through the cell membrane to interact with nuclear receptors but upregulated the c-fos gene expression when administered at concentrations comparable to DEHP concentrations; molecular docking demonstrated that DEHP has affinity for the membrane receptor integrin α_vβ₃; DEHP at 2 μmol/L upregulated the β₃ gene expression in GH3 cells; after the addition of integrin α_vβ₃-inhibiting RGD peptide, DEHP-induced c-fos gene upregulation decreased. All of these findings support the supposition that DEHP-induced thyroid-disrupting effects might be mediated by the membrane receptor integrin α_vβ₃. Moreover, DEHP activated the downstream extracellular regulated protein kinase (ERK1/2) pathway, upregulating the gene expression of raf-1, MEK-1 and MAPK1 and increasing the protein levels of p-ERK; interestingly, ERK1/2 activation and c-fos upregulation induced by DEHP were attenuated by PD98059 (an ERK1/2 inhibitor). Taken together, the data suggest that the membrane receptor integrin α_vβ₃ and the downstream ERK1/2 pathway might be involved in DEHP-induced thyroid-disrupting effects. This study provides new insight into the thyroid-disrupting effect and the underlying mechanism and will advance the effort to construct adverse outcome pathways of DEHP and other thyroid hormone disrupting chemicals.

Species differences between mouse and human PPARα in modulating the hepatocarcinogenic effects of perinatal exposure to a high-affinity human PPARα agonist in mice

Evidence suggests that species differences exist between rodents and humans in their biological responses to ligand activation of PPARα. Moreover, neonatal/postnatal rodents may be more sensitive to the effects of activating PPARα. Thus, the present studies examined the effects of chronic ligand activation of PPARα initiated during early neonatal development and continued into adulthood on hepatocarcinogenesis in mice. Wild-type, Ppara-null, or PPARA-humanized mice were administered a potent, high affinity human PPARα agonist GW7647, and cohorts of mice were examined over time. Activation of PPARα with GW7647 increased expression of known PPARα target genes in liver and was associated with hepatomegaly, increased hepatic cytotoxicity and necrosis, increased expression of hepatic MYC, and a high incidence of hepatocarcinogenesis in wild-type mice. These effects did not occur or were largely diminished in Ppara-null and PPARA-humanized mice, although background levels of hepatocarcinogenesis were also noted in both Ppara-null and PPARA-humanized mice. More fatty change (steatosis) was also observed in both Ppara-null and PPARA-humanized mice independent of GW7647 administration. Results from these studies indicate that the mouse PPARα is required to mediate hepatocarcinogenesis induced by GW7647 in mice and that activation of the human PPARα with GW7647 in PPARA-humanized mice are diminished compared to wild-type mice. Ppara-null and PPARA-humanized mice are valuable tools for examining species differences in the mechanisms of PPARα-induced hepatocarcinogenesis, but background levels of liver cancer observed in aged Ppara-null and PPARA-humanized mice must be considered when interpreting results from studies that use these models. These results also demonstrate that early life exposure to a potent human PPARα agonist does not enhance sensitivity to hepatocarcinogenesis.

Associations between medication use and phthalate metabolites in urine and follicular fluid among women undergoing in vitro fertilization

BACKGROUND

Phthalates, which are used as excipients of drugs, have been related to adverse reproductive outcomes. However, the relationships between medication use and phthalate exposure among women undergoing in vitro fertilization (IVF) have not been studied.

OBJECTIVE

To investigate the associations between the medication intake and phthalate metabolites in urine and follicular fluid (FF).

METHOD

Eight phthalate metabolites were measured in urine and FF samples from 274 women undergoing IVF using liquid chromatography-tandem mass spectrometry. Information on recent medication intake was obtained via interview by trained staff. We constructed generalized linear regression models to examine the associations of medication intake with phthalate metabolite concentrations and dose-response relationships between the number of medicines used and metabolite concentrations in two matrices.

RESULTS

Four of 10 drugs were used by more than 10% of the participants, including vitamins (23.0%), traditional Chinese medicine (TCM, 22.3%), antioxidants (12.4%) and amoxicillin (10.2%). Participants who had used TCM had 26.0% (95% CI: 0.0, 58.8%), 32.6% (95% CI: 4.2, 68.8%) and 32.3% (95% CI: 2.6, 70.6%) higher urinary mono-n-butyl phthalate (MBP), mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) and mono(2-ethyl-5-oxohexyl) phthalate (MEOHP) concentrations, respectively, than those who had not. Antioxidant intake was associated with a 30.6% (95% CI: -48.5, -6.6%) decrease in the urinary MBP concentration. Compared with non-users, women who reported the use of medicines had 53.2% (95% CI: 2.7, 128.5%) higher concentrations of MMP and a 37.7% (95% CI: -60.7, -1.5%) lower level of MBP in FF, respectively.

CONCLUSION

Our data suggest that the intake of some medications may increase phthalate exposure among women undergoing IVF.

Phthalate Exposure Pattern in Breast Milk within a Six-Month Postpartum Time in Southern Taiwan

Di-(2-ethylhexyl) phthalate (DEHP), a common plasticizer, has been detected in breast milk in many countries; however, whether phthalate metabolite concentration and the detection rate in breast milk change postpartum is still unknown. We measured phthalate metabolite concentrations in breast milk in the first 6 months postpartum in women enrolled in the E-Da hospital from January to July 2017. A total of 56 breastfeeding mothers and 66 samples were included in this study. We analyzed the samples’ concentration of eight phthalate metabolites using liquid chromatography mass spectrometry. The concentration of mono-2-ethylhexyl phthalate (MEHP) was significantly higher in the first month, and then decreased over time. The detection rate of ono-isobutyl phthalate (MiBP) and mono-n-butyl phthalate (MBP) was low in the first month and then increased over time. Compared with a previous study published in 2011, the levels of MEHP and MiBP in breast milk were much lower in the present study, suggesting an increased awareness of the health risks of phthalate exposure after a food scandal occurred in Taiwan. This study provides information for evaluating newborns’ exposure to different kinds of phthalate through human milk in the postpartum period.

Phthalates and Their Impacts on Human Health

Phthalates are a series of widely used chemicals that demonstrate to be endocrine disruptors and are detrimental to human health. Phthalates can be found in most products that have contact with plastics during producing, packaging, or delivering. Despite the short half-lives in tissues, chronic exposure to phthalates will adversely influence the endocrine system and functioning of multiple organs, which has negative long-term impacts on the success of pregnancy, child growth and development, and reproductive systems in both young children and adolescents. Several countries have established restrictions and regulations on some types of phthalates; however, we think that more countries should establish constraints or substitute measures for phthalates to reduce health risks. This article aims to summarize the adverse impacts of phthalates on human health, analyze the toxicity mechanism, assess the risks, and finally provide feasible strategies to reduce exposure of the public to phthalates.

Impact of endocrine-disrupting chemicals on steroidogenesis and consequences on testicular function

Testicular steroidogenesis is a tightly regulated process that produces the androgens important for the development, maintenance and function of the male reproductive system. These androgens are also essential for overall health, and well-being. Disruptions in the ability of the testis to form steroids can result in developmental abnormalities, dysfunction, and infertility. Endocrine-disrupting chemicals (EDCs) can interfere with the intricate signaling and metabolizing networks that produce androgens and promote their dysfunction. These chemicals are found ubiquitously in our environment, as they are integral components of products that are used every day. The effects of EDCs, such as bisphenols, phthalates, and alkyl chemicals, have been studied independently, revealing deleterious effects; but the combined influence of these structures on steroidogenesis has yet to be completely elucidated. This manuscript presents an updated review on EDC mixtures and their impact on testicular function and fertility, highlighting new findings that illustrate the anti-androgenic capabilities of EDC mixtures.

Demographic Assessment of Mono(2-ethylhexyl) Phthalate (MEHP) and Monoethyl Phthalate (MEP) Concentrations in Common Bottlenose Dolphins (Tursiops truncatus) From Sarasota Bay, FL, USA

Common bottlenose dolphins (Tursiops truncatus) have previously demonstrated exposure to phthalate esters. Phthalates and phthalate esters are commonly added to consumer goods to enhance desirable properties. As the amount of plastic marine debris increases, these chemicals can easily leach from these products into the surrounding environment. To evaluate demographic variability in exposure, eight phthalate metabolites were quantified in urine samples collected from free-ranging bottlenose dolphins sampled in Sarasota Bay, FL, USA (2010-2019; n = 51). Approximately 75% of individual dolphins had detectable concentrations of at least one phthalate metabolite. The most frequently detected metabolites were mono(2-ethylhexyl) phthalate (MEHP; n = 28; GM = 4.57 ng/mL; 95% CI = 2.37-8.80; KM mean = 7.95; s.d. = 15.88) and monoethyl phthalate (MEP; GM = 4.51 ng/mL; 95% CI = 2.77-7.34; ROS mean = 2.24; s.d. = 5.58). Urinary concentrations of MEHP and MEP were not significantly different between sex (MEHP p = 0.09; MEP p = 0.22) or age class (i.e., calf/juvenile vs. adult; MEHP p = 0.67; MEP p = 0.13). Additionally, there were no significant group differences in the likelihood of MEHP or MEP detection for any demographic as determined by a Peto-Peto test. Frequency of detection was similar for both metabolites between males and females (MEHP p = 0.10; MEP p = 0.40) as well as between juveniles and adults (MEHP p = 0.50; MEP: p = 0.60). These findings suggest ubiquitous exposure risk for both sexes and age classes, warranting further investigation into potential sources and health implications.

Nontargeted Analysis of Face Masks: Comparison of Manual Curation to Automated GCxGC Processing Tools

Masks constructed of a variety of materials are in widespread use due to the COVID-19 pandemic, and people are exposed to chemicals inherent in the masks through inhalation. This work aims to survey commonly available mask materials to provide an overview of potential exposure. A total of 19 mask materials were analyzed using a nontargeted analysis two-dimensional gas chromatography (GCxGC)-mass spectrometric (MS) workflow. Traditionally, there has been a lack of GCxGC-MS automated high-throughput screening methods, resulting in trade-offs with throughput and thoroughness. This work addresses the gap by introducing new machine learning software tools for high-throughput screening (Floodlight) and subsequent pattern analysis (Searchlight). A recursive workflow for chemical prioritization suitable for both manual curation and machine learning is introduced as a means of controlling the level of effort and equalizing sample loading while retaining key chemical signatures. Manual curation and machine learning were comparable with the mask materials clustering into three groups. The majority of the chemical signatures could be characterized by chemical class in seven categories: organophosphorus, long chain amides, polyethylene terephthalate oligomers, n-alkanes, olefins, branched alkanes and long-chain organic acids, alcohols, and aldehydes. The olefin, branched alkane, and organophosphorus components were primary contributors to clustering, with the other chemical classes having a significant degree of heterogeneity within the three clusters. Machine learning provided a means of rapidly extracting the key signatures of interest in agreement with the more traditional time-consuming and tedious manual curation process. Some identified signatures associated with plastics and flame retardants are potential toxins, warranting future study to understand the mask exposure route and potential health effects.

Potential health risks of maternal phthalate exposure during the first trimester - The Saudi Early Autism and Environment Study (SEAES)

Phthalates are the most ubiquitous contaminants that we are exposed to daily due to their wide use as plasticizers in various consumer products. A few studies have suggested that in utero exposure to phthalates can disturb fetal growth and development in humans, because phthalates can interfere with endocrine function. We collected spot urine samples from 291 pregnant women in their first trimester (9.8 ± 2.3 gestational weeks) recruited in an ongoing prospective cohort study in Saudi Arabia. A second urine sample was collected within 1-7 d after enrollment. The aims of this study were to: (1) assess the extent of exposure to phthalates during the first trimester and (2) estimate the risk from single and cumulative exposures to phthalates. Most phthalate metabolites' urinary levels were high, several-fold higher than those reported in relevant studies from other countries. The highest median levels of monoethyl phthalate, mono-n-butyl phthalate (MnBP), mono-iso-butyl phthalate (MiBP), and mono-(2-ethylhexyl) phthalate (MEHP) in μg/l (μg/g creatinine) were 245.62 (197.23), 114.26 (99.45), 39.59 (34.02), and 23.51 (19.92), respectively. The MEHP levels were highest among three di (2-ethylhexyl) phthalate (DEHP) metabolites. %MEHP₄, the ratio of MEHP to four di (2-ethylhexyl) phthalate metabolites (∑₄DEHP), was 44%, indicating interindividual differences in metabolism and excretion. The hazard quotient (HQ) of individual phthalates estimated based on the reference dose (RfD) of the U.S. Environmental Protection Agency indicated that 58% (volume-based) and 37% (creatinine-based) of the women were at risk of exposure to ∑₄DEHP (HQ > 1). Based on the tolerable daily intake (TDI) from the European Food Safety Authority, 35/12% (volume-/creatinine-based data) of the women were at risk of exposure to two dibutyl phthalate (∑DBP) metabolites (MiBP and MnBP). The cumulative risk was assessed using the hazard index (HI), the sum of HQs of all phthalates. The percentages of women (volume-/creatinine-based data) at health risks with an HI > 1 were 64/40% and 42/22% based on RfD and TDI, respectively. In view of these indices for assessing risk, our results for the anti-androgenic effects of exposing pregnant women to ∑₄DEHP and ∑DBP early during pregnancy are alarming.

The influence of prenatal exposure to phthalates on subsequent male growth and body composition in adolescence

Phthalates are ubiquitous environmental chemicals with predominantly anti-androgenic, and potentially obesogenic effects. We hypothesised that antenatal phthalate exposure may influence subsequent boy's growth and body composition through childhood and adolescence. Among 1399 singleton males from the Raine Study, 410 had maternal serum and at least one height, BMI or DEXA outcome available after birth and up to 20 years of age. Maternal serum collected at 18 and 34 weeks' gestation was pooled, and analyzed for concentrations of 32 metabolites of 15 phthalate diesters. Their serum concentrations were categorized into undetectable/detectable levels or tertiles. Linear mixed models were used to determine associations between maternal serum phthalate levels and longitudinal height and body mass index (BMI) z-scores in boys from birth to 20 years of age (n = 250 and n = 295 respectively). Linear regression was used to determine associations between maternal phthalate levels and deviation from mid-parental height (n = 177) and DEXA scan outcomes (n = 191) at the 20 year follow-up. Weak positive associations of participants height z-score increase were detected with exposure to some phthalate metabolites in particular to the lower molecular weight phthalate metabolites. Less consistent findings, by mixed model analyses, were detected for BMI and body composition, by dual energy X-ray absorptiometry (DEXA), with some positive associations of phthalate metabolites with BMI and some negative associations with DEXA fat tissue measures, although no consistent findings were evident. In conclusion, we derived some associations of childhood growth with prenatal phthalate exposure, particularly with respect to the lower molecular weight phthalate metabolites.

Secular trends of urinary phthalate metabolites in 7-year old children and association with building characteristics: Hokkaido study on environment and children's health

The widespread commercial production and use of phthalates as plasticizers in consumer products have led to significant human exposure. Some phthalates are known to disrupt the endocrine system and result in adverse health outcomes. As such, they have been regulated in materials used for children's items and food packages. In this study, we examined the secular trend of urinary phthalate metabolites in children and the association between metabolites and building characteristics. In total, 400 first-morning spot urine samples of 7 years old children collected from 2012 to 2017 from an ongoing birth cohort study were examined. Parents provided information on demographics and building questionnaires. We analyzed 10 urinary phthalate metabolites from five phthalate diesters using ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS): MiBP, MnBP, MBzP, MEHP, MEOHP, MEHHP, MECPP, MiNP, OH-MiNP, and cx-MiNP. A multivariable regression model with creatinine-corrected metabolite levels was applied to assess secular trends during 2012-2017. The association between metabolite levels and building characteristics was investigated using a mutual-adjusted linear regression. The metabolites MnBP, MEHP, MEOHP, MEHHP, MECPP, and OH-MiNP were detected in all samples. The highest median concentration was for MECPP 37.4 ng/mL, followed by MnBP and MEHHP at concentrations of 36.8 and 25.8 ng/mL, respectively. Overall, DBP, BBzP, and DINP metabolite concentrations in this study were comparable to or lower than those in previous studies from Japan and other countries in a similar study period. Higher concentrations of DEHP metabolites were observed in this study than in children from the USA and Germany, as per previous reports. Despite updated phthalate regulations and reports of production volume change in Japan, all the measured metabolites showed a stable trend between 2012 and 2017. Higher phthalate metabolite levels were observed among children from households with low annual income, those who lived in old buildings, and those with window opening habits of ≥1 h than ≤1 h. In contrast, children in houses that vacuumed 4 or more days/week showed a lower level of MnBP than those in houses that vacuumed ≤3 days/week. This study demonstrates that the internal exposure level of phthalates in Japanese children was stable from 2012 to 2017. Our findings suggest that phthalate exposure in children is consistent. Thus, improvements in the indoor environment, such as frequent vacuuming, may reduce exposure. Biomonitoring of phthalates is critical for elucidating their possible health effects and developing mitigation strategies.

Enhanced reproductive toxicities induced by phthalates contaminated microplastics in male mice (Mus musculus)

It has been demonstrated that microplastics (MPs) can transport phthalate esters (PAEs) into the tissues of mice. However, the influence of MPs on accumulation of PAEs and the combined toxicity need profound investigation. In this study, the bioaccumulation of PAEs and reproductive toxicity due to contaminated MPs exposure were investigated. After exposure to PAE-contaminated MPs for 30 days, significantly increased accumulation of PAE was observed in the liver and gut but not in the testis, which are ascribed to the distribution of MPs in tissues. Herein, most micro-size MPs accumulated in the gut and liver, while only a few nano-size MPs entered the Sertoli cells. Compared with virgin MPs and PAEs alone, PAE-contaminated MPs induced enhanced reproductive toxicities manifested by greater alterations in sperm physiology and spermatogenesis. The enhanced toxicities were also confirmed by the testicular transcriptomic alterations and aggravated oxidative stress induced by PAE-contaminated MPs. These aggravated reproductive toxicities were not caused solely by PAE, but may also be caused by the sensitization effect of oxidative stress induced by MPs. Our results highlight the potential reproductive toxicity on male terrestrial mammals due to co-exposure of MPs and plastic additives and provide valuable insights into the mechanism of combined toxicity of MPs and other pollutants.

Biochemical pathways and enhanced degradation of dioctyl phthalate (DEHP) by sodium alginate immobilization in MBR system

As one of the most representative endocrine disrupting compounds, dioctyl phthalate (DEHP) is difficult to remove due to its bio-refractory characteristic. In this study, an immobilization technology was applied in an MBR system to improve the degradation of DEHP. The degradation efficiency of DEHP was significantly improved and the number of degradation genes increased by 1/3. A bacterial strain that could effectively degrade DEHP was isolated from activated sludge and identified as Bacillus sp. The degradation pathway of DEHP was analyzed by GC-MS. DEHP was decomposed into phthalates (DBP) and Diuretic sylycol (DEP), then further to Phthalic acid (PA). PA was oxidized, dehydrogenated, and decarboxylated into protocatechins, further entered the TCA cycle through orthotopic ring opening. The DEHP degrading strain was immobilized by sodium alginate and calcium chloride under the optimized immobilization conditions, and added to MBR systems. The removal rate of DEHP (5 mg/L) (91.9%) and the number of 3, 4-dioxygenase gene copies was significantly improved by adding immobilized bacteria. Micromonospora, Rhodococcus, Bacteroides and Pseudomonas were the dominant genuses, and the results of bacterial community structure analysis show that immobilization technology is beneficial to system stability. The results showed the potential applications of the immobilized technique in DEHP wastewater treatment in MBR.

The Association of Ovarian Reserve with Exposure to Bisphenol A and Phthalate in Reproductive-aged Women

BACKGROUND

Exposure to endocrine disrupting chemicals (EDCs) that influence the hormonal and homeostatic systems is known to be associated with gynecologic health risks in many countries. In this study, we evaluated exposure to EDCs associated with diminished ovarian reserve (DOR) and gynecologic health risks.

METHODS

This cross-sectional study was performed from September 2014 to November 2014 and included 307 Korean reproductive-aged women. Anthropometric measurements, laboratory tests with urine and blood sampling and pelvic ultrasound examinations were performed.

RESULTS

Urinary bisphenol A (BLA) level was significantly higher in the DOR group with anti-Müllerian hormone lower than 25 percentile (1.89 ± 2.17 ug/g and 1.58 ± 1.08 ug/g, P < 0.05). Urinary mono-(2-ethyl-5-hydroxyhexyl) phthalate, mono-(2-ethyl-5-oxohexyl) phthalate and mono-N-butyl phthalate, and substrates of phthalate were evaluated and no significant difference was observed between the DOR group and non-DOR group. Logistic regression analysis suggested an increase in infertility in high BPA exposure group and the odds ratio (OR, 4.248) was statistically significant after adjustment for age, birth control pills, and the age of menarche, parity, and waist circumference. High phthalate exposure was associated with endometrial polyp after adjustment (OR, 2.742).

CONCLUSION

BPA exposure might be associated with DOR and infertility. Meanwhile, endometrial polyp is increased in women with high phthalate exposure. Therefore, the risk of exposures to EDCs for reproduction should be a matter of concern in reproductive-aged women.

The role of epigenetics in the reproductive toxicity of environmental endocrine disruptors

Environmental endocrine disruptors (EEDs) seriously endanger human health by interfering with the normal function of reproductive systems. In males, EEDs can affect sperm formation and semen quality as well spermatogenesis, ultimately reducing fertility. In females, EEDs can affect uterine development and the expression levels of reproduction-related genes, ultimately reducing female fertility and the normal development of the fetus. There are a large number of putative mechanisms by which EEDs can induce reproductive toxicity, and many studies have shown the involvement of epigenetics. In this review, we summarize the role of DNA methylation, noncoding RNAs, genomic imprinting, chromatin remodeling and histone modification in the reproductive toxicity of EEDs.

Testicular dysgenesis syndrome and phthalate exposure: A review of literature

Endocrine disruptors are chemicals that interfere with the body's endocrine system and cause adverse effects in biological systems. Phthalates are a group of man-made chemicals which are mainly used as plasticizers and classified as endocrine disruptors. They are also used in cosmetic and personal care products as color or smell fixators. Moreover, phthalates are present in inks, adhesives, sealants, automobile parts, tools, toys, carpets, medical tubing and blood storage bags, and food packages. Pathological condition known as "testicular dysgenesis syndrome" (TDS) or "phthalate syndrome" is usually linked to phthalate exposure and is coined to describe the rise in alterations in reproductive health in men, such as reduced semen quality (decrease in sperm counts, sperm motility and increase in abnormal sperms), hypospadias, cryptorchidism, reduced anogenital distance and early-life testicular cancer. Phthalates are suggested to cause direct effect on gonadal and non-gonadal tissues, impair the differentiation and morphogenesis of seminiferous tubules and accessory sex organs and testicular cells (both Sertoli and Leydig cells), alter estradiol and/or testosterone levels, decrease insulin-like 3 (INSL3) peptide production, impair spermatogenesis and lead to epigenetic alterations, all of which may lead to TDS. This review will mainly focus on phthalates as causes of TDS and their mechanisms of action.

Independent and combined effects of Bisphenol A and Diethylhexyl Phthalate on gestational outcomes and offspring development in Sprague-Dawley rats

Bisphenol A (BPA) and Diethylhexyl Phthalate (DEHP) are well-studied endocrine disrupting chemicals (EDCs), however, the effects of mixtures of these EDCs are not. To assess the consequences of prenatal exposure to a mixture of these EDCs, dams were orally administered either saline (control), BPA (5 μg/kg BW/day), high dose DEHP (HD-D; 7.5 mg/kg BW/day), or a combination of BPA with HD-D in experiment 1; saline, BPA (5 μg/kg BW/day), low-dose DEHP (LD-D; 5 μg/kg BW/day) or a combination of BPA with LD-D in experiment 2. Gestational weights, number of abortions, litter size and weights, number of live births and stillbirths were recorded. Morphometric measures were obtained at birth and body weight, food and water intake were monitored weekly from postnatal weeks 3-12. Offspring were sacrificed at 16-24 weeks of age and organ weights were measured. The abortion rate of dams exposed to HD-D and the mixtures, BPA + LD-D and BPA + HD-D were higher at 9, 14 and 27% respectively. Prenatal exposure to BPA or HD-D significantly decreased relative thymus weights in male but not female offspring. Apoptotic cells were detected in thymus sections of both male and female offspring prenatally exposed to DEHP. Relative heart weights increased in BPA + HD-D exposed male offspring compared to the other groups. The results indicate that a mixture of BPA and DEHP, produced a pronounced effect on pregnancy outcomes. Male offspring appear to be more susceptible to the programming effects of these EDCs or their mixture suggesting a need to reconsider the possible additive, antagonistic or synergistic effects of EDC mixtures.

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

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

Occurrence, removal, and environmental risk of phthalates in wastewaters, landfill leachates, and groundwater in Poland

Phthalates or phthalic acid esters (PAEs) are chemical compounds whose use is exceptionally widespread in everyday materials but, at the same time, have been proven to have harmful effects on living organisms. Effluents from municipal wastewater treatment plants (WWTP) and leachates from municipal solid waste (MSW) landfills are important sources of phthalates with respect to naturally occurring waters. The main aim of this research was determination, mass loads, removal rates and ecological risk assessment of eight phthalates in municipal wastewaters, landfill leachates and groundwater from Polish WWTPs and MSW landfills. Solid-phase microextraction and gas chromatography with mass spectrometry were used for the extraction and determination of analytes. Summed up concentrations of eight phthalates ranged from below LOD to 596 μg/L in influent wastewater with the highest concentration found for bis-2-ethylhexyl phthalate (DEHP) (143 μg/L). The average degree of phthalate removal varies depending on the capacity of a given treatment plant with larger treatment plants coping better than smaller ones. The highest treatment efficiency for all tested treatment plants, over 90%, was reported for dimethyl phthalate (DMP) and diethyl phthalate (DEP). Overall concentrations of phthalates in leachates ranged from below LOD to 303 μg/L while the highest maximum concentration was registered for DEHP (249 μg/L). Overall concentrations of phthalic acid esters in groundwater from upstream monitoring wells ranged from below LOD to 1.8 μg/L and from LOD to 27.9 μg/L in samples from wells downstream of MSW landfills. The obtained data shows that diisobutyl phthalate (DIBP), dibutyl phthalate (DBP), DEHP, and diisononyl phthalate (DINP) pose a high risk for all trophic levels being considered in effluent wastewaters. In the case of groundwater high environmental risk was recorded for DBP and DEHP for all tested trophic levels. Phthalates, in concentrations that pose a high environmental risk, are present in Polish municipal after-treatment wastewater as well as in groundwater under municipal solid waste landfills.

Impact of environmental toxin exposure on male fertility potential

Idiopathic infertility is the most common individual diagnosis in male infertility, representing nearly 44% of cases. Research studies dating over the last half-century consistently demonstrate a decline in male fertility that is incompletely explained by obesity, known genetic causes, or diet and lifestyle changes alone. Human exposures have changed dramatically over the same time course as this fertility decline. Synthetic chemicals surround us. Some are benevolent; however, many are known to cause disruption of the hypothalamic-pituitary-gonadal axis and impair spermatogenesis. More than 80,000 chemicals are registered with the United States National Toxicology Program and nearly 2,000 new chemicals are introduced each year. Many of these are known toxins, such as phthalates, polycyclic aromatic hydrocarbons, aromatic amines, and organophosphate esters, and have been banned or significantly restricted by other countries as they carry known carcinogenic effects and are reproductively toxic. In the United States, many of these chemicals are still permissible in exposure levels known to cause reproductive harm. This contrasts to other chemical regulatory legislature, such as the European Union's REACH (Registration, Evaluation, Authorization and Restriction of Chemicals) regulations which are more comprehensive and restrictive. Quantification of these diverse exposures on an individual level has proven challenging, although forthcoming technologies may soon make this data available to consumers. Establishing causality and the proportion of idiopathic infertility attributable to environmental toxin exposures remains elusive, however, continued investigation, avoidance of exposure, and mitigation of risk is essential to our reproductive health. The aim of this review is to examine the literature linking changes in male fertility to some of the most common environmental exposures. Specifically, pesticides and herbicides such as dichlorodiphenyltrichloroethane (DDT), dibromochloropropane (DBCP), organophosphates and atrazine, endocrine disrupting compounds including plastic compounds phthalates and bisphenol A (BPA), heavy metals, natural gas/oil, non-ionizing radiation, air and noise pollution, lifestyle factors including diet, obesity, caffeine use, smoking, alcohol and drug use, as well as commonly prescribed medications will be discussed.

Gestational and childhood exposure to phthalates and child behavior

BACKGROUND

Early-life phthalate exposures may adversely influence neurodevelopment by disrupting thyroid hormone homeostasis, altering brain lipid metabolism, or reducing gonadal hormone concentrations. Previous literature examining gestational phthalate exposure and child behavior were inconclusive and few prospective studies have examined childhood phthalate exposure, particularly phthalate mixtures. We investigated whether gestational and childhood phthalate exposures were associated with child behavior.

METHODS

We used data from 314 mother-child pairs in the HOME Study, a longitudinal pregnancy and birth cohort that enrolled pregnant women from Cincinnati, Ohio. We quantified urinary concentrations of 11 phthalate metabolites in samples collected twice during gestation from women and six times from their children when they were ages 1, 2, 3, 4, 5, and 8 years. We assessed children's behavior at ages 2, 3, 4, 5, and 8 years using the Behavioral Assessment System for Children-2. Using linear mixed models, we estimated covariate-adjusted associations of measurement-error-corrected gestational and childhood phthalate metabolite concentrations (per interquartile range increase) with repeated child behavior assessments. We used Weighted Quantile Sum (WQS) regression to estimate the association of phthalate mixtures with child behavior.

RESULTS

Gestational mono(3-carboxypropyl) phthalate (MCPP) concentrations were associated with more problem behaviors (internalizing: β = 0.9, 95% confidence interval [CI] = -0.1, 1.9; externalizing: β = 1.0, 95%CI = -0.1, 2.0; behavioral symptoms index [BSI]: β = 1.1, 95%CI = 0.1, 2.1). Higher childhood monobenzyl phthalate (MBzP) (β = 1.4; 95%CI = 0.0, 2.7), monocarboxynonyl phthalate (MCNP) (β = 3.2; 95%CI = 1.6, 4.8), monocarboxyoctyl phthalate (MCOP) (β = 0.9; 95%CI = 0.0, 1.7), MCPP (β = 1.8; 95%CI = 0.2, 3.5), and monoethyl phthalate (MEP) (β = 1.6; 95%CI = 0.1, 3.1) concentrations were associated with higher BSI composite scores. Consistent with this, the weighted childhood phthalate index was associated with more problem behaviors (internalizing: β = 1.5, 95%CI = -0.2, 3.1; externalizing: β = 1.7, 95%CI = 0.1, 3.5; BSI: β = 1.7, 95%CI = 0.2, 3.2); MBzP, MCNP, and MEP largely contributed to these associations.

CONCLUSION

Our findings suggest that childhood exposure to phthalate mixtures may be associated with children's problem behaviors.

Risk assessment of phthalates based on aggregated exposure from foods and personal care products and comparison with biomonitoring data

Phthalates are a group of diesters of phthalic acid and have been widely used by the industry as plasticisers giving flexibility and durability to polyvinyl chloride (PVC) plastics. Commonly their uses vary from plasticisers in food contact materials and toys to emulsifying agents in personal care products. Phthalates are not covalently bound to PVC, thus they can migrate into the air, skin, water, food and the environment. The omnipresence of phthalates results in human exposure via multiple pathways such as dermal, oral and inhalation for prolonged periods. There is evidence that phthalates can induce disruption in oestrogenic activity, reproductive, developmental and liver toxicity both in experimental animals and potentially in humans. The aim of this technical report is to summarise the activities of the fellow performed at the Norwegian Institute of Public Health (NIPH). The goals of the work programme were collecting concentration levels on five specific phthalates from the scientific literature and combining them with consumption/use data reported in a biomonitoring study part of a Horizon 2020 project (EuroMix), and finally, estimate the aggregate phthalate exposure from food and personal care products and compare them with the measured phthalate levels in urine samples collected in the biomonitoring study.

Temporal Trends of Exposure to Phthalates and Phthalate Alternatives in California Pregnant Women during 2007-2013: Comparison with Other Populations

Phthalates with potential adverse health effects are being replaced by other phthalates or phthalate alternatives. Little is known about temporal trends of phthalate exposure in pregnant women in the United States. We quantified 16 metabolites of eight phthalates and di(isononyl) cyclohexane-1,2-dicarboxylate (DINCH) in 656 urine samples collected from 192 California pregnant women in 2007-2013 during their second and third trimesters of pregnancy who participated in the MARBLES (Markers of Autism Risk in Babies-Learning Early Signs) study. We used multiple regression to estimate least squares geometric means of phthalate biomarker concentrations and annual percent changes over the study period. Biomarker concentrations of diethyl phthalate (DEP) and three phthalates with known toxicity and adverse health effects (i.e., butyl benzyl phthalate [BBzP], dibutyl phthalate [DBP], di(2-ethylhexyl) phthalate [DEHP]) decreased, while those of di-isobutyl phthalate [DiBP], di-isononyl phthalate [DiNP], and di-n-octyl phthalate [DOP] increased in California pregnant women during our study period. To understand broad social forces that may influence temporal trends and geographic variations in phthalate exposure across countries, we compared our phthalate biomarker concentrations with those of other populations. We observed over a factor of 2 differences in exposure across countries for some phthalate biomarkers and between pregnant and nonpregnant women for DEP.

Similar names, different results: Consistency of the associations between prenatal exposure to phthalates and parent-ratings of behavior problems in preschool children

BACKGROUND

Environmental health research has reported mixed findings on the associations between prenatal exposure to phthalates and parent-ratings of child behavioral problems.

OBJECTIVE

We examined the consistency of the associations between prenatal urinary phthalate concentrations and child behavior scores across two standardized instruments - the Behavior Assessment System for Children-Second Edition (BASC-2) and the Child Behavior Checklist (CBCL) - using two analytical approaches used to correct for urine dilution.

METHOD

A sample of 351 mother-child pairs were selected from a prospective birth cohort of pregnant women enrolled between 2009 and 2012. Women provided spot urine samples during the second trimester of pregnancy, which were analyzed for levels of nine urinary phthalate metabolites. When their typically developing children were 3-4 years of age, mothers completed the BASC-2 and CBCL on the same day. Adjusted regression analyses examined the associations between maternal prenatal phthalate concentrations and child behavior scores on the BASC-2 and CBCL. To correct for urine dilution, primary regression analyses included urinary creatinine concentration as a separate independent variable (i.e., covariate). In the secondary regression analyses, creatinine-adjusted phthalate concentrations were used.

RESULTS

Primary logistic regression analyses that included urinary creatinine as a covariate showed that higher prenatal phthalate concentrations were related to increased odds of scores falling into the borderline or clinical range on the Hyperactivity, Aggression, Anxiety, Depression, Withdrawal, Externalizing Problems, Internalizing Problems, and Behavioral Symptoms Index scales on the BASC-2 (ORs from 1.39 to 2.07), but only the Anxious/Depressed and Externalizing Problems scales on the CBCL (ORs from 1.80 to 3.28). Primary linear regression analyses showed that higher prenatal phthalate concentrations were related to higher scores on the Externalizing Problems (β's = 0.16), Internalizing Problems (β's from 0.16 to 0.20), and Behavioral Symptoms Index (β's from 0.18 to 0.21) scales on the BASC-2, but not related to any CBCL scales. Sex-stratified analyses found that many associations were only significant for male children. Secondary analyses using creatinine-adjusted phthalate concentrations revealed that some of the associations from the primary analyses remained significant; however, a number of unique associations were observed.

CONCLUSION

Prenatal phthalate exposure was associated with preschool behavioral development; however, findings were not consistent for the BASC-2 and CBCL, especially related to the clinical/syndrome scales and Internalizing Problems scale. Further, many findings differed based on the analytical approach used to correct for urine dilution. Future work is needed to delineate the similarities and differences between similarly named child behavior constructs assessed by different neurodevelopmental assessments. Also, research is needed to better understand why and how different analytical approaches influence the reported associations between maternal prenatal phthalate concentrations and children's behavior problems.

Plastic-derived contaminants in Aleutian Archipelago seabirds with varied foraging strategies

Phthalates, plastic-derived contaminants, are of increasing global concern. This study quantified phthalates in seabirds collected across >1700 km of the Aleutian Islands, Alaska, and contributes to a body of knowledge on plastic contaminants in marine wildlife. We measured six phthalate congeners in seabirds representing ten species and four feeding guilds. Phthalates were detected in 100% of specimens (n = 115), but varied among individuals (3.64-539.64 ng/g). DEHP and DBP occurred at an order of magnitude higher than other congeners. Total phthalates did not vary geographically, but differed among feeding guilds, with significantly higher concentrations in diving plankton-feeders compared to others. Plastic particles were detected in 36.5% of randomly subsampled seabird stomachs (n = 74), suggesting plastic ingestion as a potential route of phthalate exposure. Our findings suggest feeding behavior could influence exposure risk for seabirds and lend further evidence to the ubiquity of plastic pollutants in marine ecosystems.

Sex-Specific Programming of Cardiac DNA Methylation by Developmental Phthalate Exposure

Phthalate plasticizers are ubiquitous chemicals linked to several cardiovascular diseases in animal models and humans. Despite this, the mechanisms by which phthalate exposures cause adverse cardiac health outcomes are unclear. In particular, whether phthalate exposures during pregnancy interfere with normal developmental programming of the cardiovascular system, and the resulting implications this may have for long-term disease risk, are unknown. Recent studies suggest that the effects of phthalates on metabolic and neurobehavioral outcomes are sex-specific. However, the influence of sex on cardiac susceptibility to phthalate exposures has not been investigated. One mechanism by which developmental exposures may influence long-term health is through altered programming of DNA methylation. In this work, we utilized an established mouse model of human-relevant perinatal exposure and enhanced reduced representation bisulfite sequencing to investigate the long-term effects of diethylhexyl phthalate (DEHP) exposure on DNA methylation in the hearts of adult male and female offspring at 5 months of age (n = 5-7 mice per sex and exposure). Perinatal DEHP exposure led to hundreds of sex-specific, differentially methylated cytosines (DMCs) and differentially methylated regions (DMRs) in the heart. Pathway analysis of DMCs revealed enrichment for several pathways in females, including insulin signaling, regulation of histone methylation, and tyrosine phosphatase activity. In males, DMCs were enriched for glucose transport, energy generation, and developmental programs. Notably, many sex-specific genes differentially methylated with DEHP exposure in our mouse model were also differentially methylated in published data of heart tissues collected from human heart failure patients. Together, these data highlight the potential role for DNA methylation in DEHP-induced cardiac effects and emphasize the importance of sex as a biological variable in environmental health studies.

Skin transferability of phthalic acid ester plasticizers and other plasticizers using model polyvinyl chloride sheets

The transferability of phthalic acid esters (PAEs) and other plasticizers, from model polyvinyl chloride (PVC) sheets to the skin of 11 subjects was assessed by measuring the amount of substance transferred using PVC sheets containing PAEs and alternative plasticizers of different types and contents. For all subjects, the transferred amount, from sheets containing 28 wt% PAE or from mixed sheets containing 14 wt% each of di (2-ethylhexyl) phthalate (DEHP) and other PAE, was greater than that from sheets containing 15 wt% each of PAE or alternative plasticizer only. A comparison of the transferability of five types of PAE showed that transfer tended to occur more readily as the n-octanol-water partition coefficient increased, suggesting that PAE hydrophobicity affected its transferability. The transferability of the alternative plasticizers di(2-ethylhexyl) terephthalate and 1,2-cyclohexane dicarboxylic acid diisononyl ester showed a similar trend; however, the transferred amount tended to be higher from model PVC sheets containing 28 wt% PAE or mixed with DEHP. The transferability of PAEs and alternative plasticizers was higher for certain subjects, suggesting individual differences in the transferability of chemicals to the subject's skin surface and is the presence of a group of people comparatively more susceptible to such transfer.

Correlations of phthalate metabolites in urine samples from fertile and infertile men: Free-form concentration vs. conjugated-form concentration

In previous studies, the total content of urinary phthalate metabolites was commonly used to evaluate human exposure to phthalates. However, phthalate metabolites are mainly present in urine in two forms, conjugated and free. These metabolite forms in urine are more relevant to the biotransformation pathways of the phthalates in humans. Therefore, the concentration of these forms is more relevant to exposure related health outcomes than total content. In this study, instead of measuring total content, the free- and conjugated-form concentrations of phthalate metabolites in the urine of fertile and infertile men were measured. The main metabolites in urine of both groups are monoethyl phthalate (MEP) and the di-(2-ethylhexyl) phthalate (DEHP) metabolites. The geometric means of their both conjugated- and free-forms in the infertile group were higher than in the fertile group, specifically, 24.3 and 43.4 μg/g creatinine vs 8.5 and 28.9 μg/g creatinine, respectively, for MEP, and 50.0 and 9.1 μg/g creatinine vs 39.1 and 8.4 μg/g creatinine, respectively for total DEHP metabolites. We investigated the correlations of free- and conjugated-form phthalate metabolite concentrations between the infertile and fertile group as well as among different phthalate metabolites. The results showed that there was a statistically significant difference between the infertile and fertile group for monobenzyl phthalate (MBzP) in both free-form and conjugated-form. However, there was only a statistically significant difference between the two groups for conjugated-form MEP and MEHP, and no statistically significant difference between the two groups for free-form MEP and MEHP. The results of the Pearson correlation test revealed that the correlations between DEHP metabolites and the correlations between mid-sized phthalate metabolites (mono-n-butyl phthalate (MnBP), mono-isobutyl phthalate (MiBP) and mono-benzyl phthalate (MBzP)) were stronger than between these two clusters of metabolites. This study is the first attempt to examine possible effects of conjugated-form concentrations of phthalate metabolites on human fertility. The results of this study suggest that conjugated-form and free-form concentrations of urinary phthalate metabolites may be appropriate biomarkers for assessing human exposure to phthalates and association with health outcomes.

Postnatal di-2-ethylhexyl phthalate exposure affects hippocampal dentate gyrus morphogenesis

Di-2-ethylhexyl phthalate (DEHP) is the most commonly used phthalate for the production of flexible polyvinyl chloride. Recent studies in humans reported a widespread DEHP exposure, raising concerns in infants whose metabolic and excretory systems are immature. DEHP is a potential endocrine-disrupting chemical, but the effects of postnatal DEHP exposure on neuronal development are unclear. The dentate gyrus (DG) is critical in the consolidation of information from short- to long-term memory, as well as spatial learning. We evaluated neurodevelopmental toxicity due to neonatal DEHP exposure by assessing neurogenesis in the DG. Newborn mice were orally administered DEHP from postnatal day (PND) 12 to 25. We performed immunostaining using neuronal markers at different stages to assess whether DEHP exposure affects neurons at specific differentiation stages at PND 26 and PND 110. We found that in mice, postnatal DEHP exposure led to a decrease in the number of Type-1, -2a, -2b, and -3 neural progenitor cells, as well as granule cells in the hippocampal DG at PND 26. Further, the results showed that neural progenitor cell proliferation and differentiation were also reduced in the hippocampal DG of the DEHP-exposed mice. However, no effect on memory and learning was observed. Overall, our results suggest that neurodevelopmental toxicity due to postnatal DEHP exposure might affect postnatal DG morphogenesis.

Phthalate and Bisphenol Exposure during Pregnancy and Offspring Nonverbal IQ

BACKGROUND

Prenatal exposures to phthalates and bisphenols are associated with impaired brain development in animals. However, epidemiological studies investigating the association between prenatal phthalate or bisphenol exposure and cognition have produced mixed findings and mostly had modest sample sizes and measured the exposure during the third trimester.

OBJECTIVE

We examined the association between pregnancy maternal urinary biomarkers of phthalate or bisphenol exposure and nonverbal intelligence quotient (IQ) in children 6 years of age.

METHOD

The study sample consisted of 1,282 mother-child pairs participating in the Generation R Study, a population-based birth cohort in Rotterdam, Netherlands (enrollment 2002-2006). We measured maternal urinary concentrations of 18 phthalate metabolites and 8 bisphenols at < 18 , 18-25, and > 25  wks of gestation. Child nonverbal IQ was measured at 6 years of age using the Snijders-Oomen Nonverbal Intelligence Test-Revised. Linear regression models were fit for each of the three collection phases separately, the three collection phases jointly, and for the averaged prenatal exposure across pregnancy.

RESULTS

Higher urinary concentrations of phthalate metabolites during early pregnancy were associated with lower child nonverbal IQ score [e.g., B per 10-fold increase in summed low-molecular weight phthalates = - 1.7 (95% CI: - 3.1 , - 0.3 )]. This association remained unchanged when adjusted for mid and late pregnancy exposures. We also observed an inverse association between late pregnancy di-n-octyl phthalate (DNOP) exposure and nonverbal IQ. Maternal urinary concentrations of bisphenols were not associated with child nonverbal IQ. There was no effect estimate modification by sex.

CONCLUSIONS

We did not observe that maternal biomarkers of bisphenol exposure are associated with nonverbal IQ. We found that phthalate exposure in early pregnancy and DNOP exposure in late pregnancy are associated with lower nonverbal IQ scores in children. Our results might suggest that particularly early pregnancy is a sensitive window of phthalate exposure, but future studies are needed to replicate our findings. https://doi.org/10.1289/EHP6047.

The preconception environment and sperm epigenetics

BACKGROUND

Infertility is a common reproductive disorder, with male factor infertility accounting for approximately half of all cases. Taking a paternal perceptive, recent research has shown that sperm epigenetics, such as changes in DNA methylation, histone modification, chromatin structure, and noncoding RNA expression, can impact reproductive and offspring health. Importantly, environmental conditions during the preconception period has been demonstrated to shape sperm epigenetics.

OBJECTIVES

To provide an overview on epigenetic modifications that regulate normal gene expression and epigenetic remodeling that occurs during spermatogenesis, and to discuss the epigenetic alterations that may occur to the paternal germline as a consequence of preconception environmental conditions and exposures.

MATERIALS AND METHODS

We examined published literature available on databases (PubMed, Google Scholar, ScienceDirect) focusing on adult male preconception environmental exposures and sperm epigenetics in epidemiologic studies and animal models.

RESULTS

The preconception period is a sensitive developmental window in which a variety of exposures such as toxicants, nutrition, drugs, stress, and exercise, affects sperm epigenetics.

DISCUSSION AND CONCLUSION

Understanding the environmental legacy of the sperm epigenome during spermatogenesis will enhance our understanding of reproductive health and improve reproductive success and offspring well-being.

A moderate physiological dose of benzyl butyl phthalate exacerbates the high fat diet-induced diabesity in male mice

Exposure to endocrine disrupting chemicals (EDCs) used in plastic manufacturing processes may be contributing to the current increase in metabolic disorders. Here, we determined that benzyl butyl phthalate (BBP), a common EDC and food packaging plasticizer, mixed into chow diet (CD) and high fat diets (HFD) at varying concentrations (4 μg/kg body weight (bw)/day, 169 μg/kg bw/day, 3 mg/kg bw/day, 50 mg/kg bw/day) produced a number of detrimental and sex-specific metabolic effects in C57BL/6 male and female mice after 16 weeks. Male mice exposed to moderate (3 mg/kg bw/day) concentrations of BBP in an HFD were especially affected, with significant increases in body weight due to significant increases in weight of liver and adipose tissue. Other doses did not show any significant changes when compared to only CD or HFD alone. HFD in the presence of 3 mg/kg bw/day BBP showed significant increases in fasting blood glucose, glucose intolerance, and insulin intolerance when compared to HFD alone. Furthermore, this group significantly alters transcriptional regulators involved in hepatic lipid synthesis and its downstream pathway. Interestingly, most of the BBP doses had no phenotypic effect when mixed with CD and compared to CD alone. The female mice did not show a similar response as the male population even though they consumed a similar amount of food. Overall, these data establish a dose which can be used for a BBP-induced metabolic research model and suggest that a moderate dosage level of EDC exposure can contribute to widely ranging metabolic effects.

Phthalates levels in olive oils and olive pomace oils marketed in Turkey

Phthalates are used as additives and plasticisers in packaging for personal care and food products. Several investigations reported the harmful impact of phthalates on human health. In this study, different types of olive oils (12 olive oil; 20 extra virgin oil; 4 refined pomace oil) in different packaging materials [polyethylene terephthalate (PET), glass and metal] obtained from local markets in Turkey in 2019, were analysed using GC-MS for the presence of benzyl butyl phthalate (BBP), di(2-ethylhexyl) phthalate (DEHP), diisononyl phthalate (DINP), dibutyl phthalate (DBP), and diisodecyl phthalate (DIDP). The average recoveries of the 5 phthalates in olive oils were 87%-100%, with limits of quantification (LOQs) of 0.09-2.28 mg/kg. DEHP was the abundant phthalate in all olive oil samples ranging from below the LOQ (0.23 mg/kg) to 602 mg/kg. In all analysed samples, the levels of DINP and DIDP were less than their LOQ, thus these phthalates were not detected. The highest DEHP content was found in an olive oil sample containing 602 mg/kg, whilst 5 samples did not contain detectable phthalate esters.

Gut microbiota dysbiosis might be responsible to different toxicity caused by Di-(2-ethylhexyl) phthalate exposure in murine rodents

Di-(2-ethylhexyl) phthalate (DEHP) is widely used as a plasticizer, which can enter the body through a variety of ways and exerted multiple harmful effects, including liver toxicity, reproductive toxicity and even glucose metabolism disorder. Many studies have suggested that changes of gut microbiota are closely related to the occurrence of various diseases, but the effects of DEHP exposure on gut microbiota are still unclear. It was found in this study that the damage to different tissues by DEHP on two strains each from two different species of male rodents before puberty was dose and time of exposure dependent, and also depending on the strain and species of rodent. Sprague-Dawley (SD) rats showed highest sensitivity to DEHP exposure, with most severe organ damage, highest Th1 inflammatory response and most significant body weight gain. Correspondingly, the gut microbiota of SD rats showed most significant changes after DEHP exposure. Only SD rats, but not Wistar rats, BALB/c and C57BL/6J mice showed an increase in Firmicutes/Bacteroidetes ratio and Proteobacteria abundance in the fecal samples, which are known to associate with obesity and diabetes. This is consistent with the increasing body weight gain which was only found in SD rats. In addition, the decrease in the level of butyrate, increase in the abundance of potential pathogens and microbial genes linked to colorectal cancer, Parkinson's disease, and type 2 diabetes in the SD rats were associated with issue and functional damages and Th1 inflammatory response caused by DEHP exposure. We postulate that the differential effects of DEHP on gut microbiota may be an important cause of the differences in the toxicity on different strains and species of rodents to DEHP.

Di-(2-ethylhexyl) phthalate inhibits expression and internalization of transthyretin in human placental trophoblastic cells

During pregnancy, fetal thyroid hormones (THs) are dependent on maternal placental transport and their physiological level is crucial for normal fetal neurodevelopment. Earlier research has shown that Di-(2-ethylhexyl) phthalate (DEHP) disrupts thyroid function and THs homeostasis in pregnant women and fetuses, and affects placental THs transport. However, the underlying mechanisms are poorly understood. The present study, therefore, aimed to systematically investigate the potential mechanisms of DEHP-induced disruption in the placental THs transport using two human placental trophoblastic cells, HTR-8/SVneo cells and JEG-3 cells. While the exposure of DEHP at the doses of 0-400 μM for 24 h did not affect cell viability, we found reduced consumption of T3 and T4 in the culture medium of HTR-8/Svneo cells treated with DEHP at 400 μM. DEHP treatment did not affect T3 uptake and the expression of monocarboxylate transporters 8 (MCT8) and organic anion transporters 1C1 (OATP1C1). However, DEHP significantly inhibited transthyretin (TTR) internalization, down-regulated TTR, deiodinase 2 (DIO2), and thyroid hormone receptors mRNA expression and protein levels, and up-regulated deiodinase 3 (DIO3) protein levels in a dose-dependent manner. These results indicate that DEHP acts on placental trophoblast cells, inhibits its TTR internalization, down-regulates TTR expression and affects the expression of DIO2, DIO3, and thyroid hormone receptor. These may be the mechanisms by which PAEs affects THs transport through placental.

The Impact on Antioxidant Enzyme Activity and Related Gene Expression Following Adult Zebrafish (Danio rerio) Exposure to Dimethyl Phthalate

Simple Summary

Dimethyl phthalate (DMP) is a widespread environmental contaminant and its toxicological effects on fish have not been adequately examined. Our present study clearly showed that a high concentration induced oxidative damage in zebrafish, which proved the molecular regulation due to the negative effects of DMP, along with the physical damage in zebrafish. We also found that antioxidant enzymes might be used as appropriate biochemical markers for the toxic identification of DMP.

Abstract

Dimethyl phthalate (DMP) is a widespread environmental contaminant that poses potential toxicity risks for animals and humans. However, the toxicological effects of DMP on fish have not been adequately examined. In this study, the acute toxicity, oxidative damage, antioxidant enzyme activities, and relative gene expression patterns were investigated in the liver of adult zebrafish (Danio rerio) exposed to DMP. We found that the lethal concentration (LC₅₀) of DMP for zebrafish after 96 h of exposure was 45.8 mg/L. The zebrafish that were exposed to low, medium and high concentrations of DMP (0.5, 4.6, and 22.9 mg/L, respectively) for 96 h had an increased malondialdehyde (MDA) content and a lower antioxidant capacity compared with the control solvent group. The total superoxide dismutase (SOD) activity was significantly higher than 0 h after initial exposure for 24 h at low concentrations, and then decreased at high concentrations after exposure for 96 h. The catalase (CAT) and glutathione S-transferase (GST) activities were significantly reduced after 96 h of exposure to high concentrations of DMP, with the up- or down-regulation of the related transcriptional expression. These findings indicated that DMP could cause physiological effects in zebrafish by disturbing the expression levels of antioxidant enzymes. These results might contribute to the identification of biomarkers to monitor phthalate pollution.

Biomonitoring of bisphenols A and S and phthalate metabolites in hair from pregnant women in Crete

Phthalates, bisphenols A and S (BPA, BPS) are used as plasticizers and many of them are documented or suspected of being endocrine disruptors. Several studies indicate that exposure during pregnancy may affect the newborn's health and development. The aim of this cross-sectional study is the biomonitoring of seven phthalate metabolites, BPA and BPS in hair from 100 pregnant women in Crete. The most frequently detected compounds were monoethylhexyl phthalate (mEHP) (68%), mono isobutyl phthalate (miBP) (40%), BPA (37%), BPS (34%) and mono-n-butyl phthalate (mnBP) (28%). Phthalate metabolites were detected at medians from 19.5 to 44.4 pg/mg, BPA at 69.9 pg/mg and BPS at 3.5 pg/mg. Significant positive correlations between phthalate metabolites were found which indicated their common sources of exposure. The frequent use of plastics for food storage was strongly associated with mEHP (p = .013) and a weaker association was found for miBP (p = .063). The frequent use of cosmetics during or before pregnancy was associated with levels of phthalate metabolites in hair. More specifically, the use of hair spray before pregnancy was significantly correlated with monobenzyl phthalate (mBzP) (p = .041) and a trend was found for miBP (p = .066). The use of makeup products during pregnancy was strongly associated with miBP (p = .015) and the use of deodorant during pregnancy was inversely associated with mEHP (p = .021). Strong associations came up between mEHP and lower birth weight (Spearman correlation coefficient, r = -0.302, p = .021) and exposure to BPS was associated with increased body mass index of the participants (p = .036). Although data in literature on biomonitoring of the compounds in hair are limited, the findings of this study are promising and in agreement with existing data in hair or urine.

Association of Parental Preconception Exposure to Phthalates and Phthalate Substitutes With Preterm Birth

IMPORTANCE

Although phthalate exposure during pregnancy has been associated with preterm birth, the association of preconception exposure in either parent with preterm birth constitutes a knowledge gap.

OBJECTIVE

To examine the association of paternal and maternal preconception urinary concentrations of biomarkers of phthalates and phthalate substitutes with singleton preterm birth.

DESIGN, SETTING, AND PARTICIPANTS

This study, conducted at an academic fertility center in Boston, Massachusetts, included a prospective preconception cohort of subfertile couples comprising 419 mothers and 229 fathers and their 420 live-born singleton offspring born between January 1, 2005, and December 31, 2018. Statistical analysis was performed from August 1 to October 31, 2019.

EXPOSURES

Urinary concentrations of metabolites of phthalates and phthalate substitutes obtained before conception.

MAIN OUTCOMES AND MEASURES

Gestational age was abstracted from delivery records and validated using the American College of Obstetricians and Gynecologists guidelines for births after medically assisted reproduction. The risk ratio (RR) of preterm birth (live birth before 37 completed weeks' gestation) was estimated in association with urinary concentrations of 11 individual phthalate metabolites, the molar sum of 4 di-(2-ethylhexyl) phthalate (ΣDEHP) metabolites, and 2 metabolites of 1,2-cyclohexane dicarboxylic acid diisononyl ester (DINCH, a nonphthalate plasticizer substitute) using modified Poisson regression models adjusted for covariates.

RESULTS

The mean (SD) age of the 419 mothers was 34.7 (4.0) years, the mean (SD) age of the 229 fathers was 36.0 (4.5) years, and the mean (SD) gestational age of the 420 singleton children (217 boys) was 39.3 (1.7) weeks, with 34 (8%) born preterm. In adjusted models, maternal preconception ΣDEHP concentrations (RR, 1.50; 95% CI, 1.09-2.06; P = .01) and cyclohexane-1,2-dicarboxylic acid monohydroxy isononyl ester (MHiNCH, a metabolite of DINCH) concentrations (RR, 1.70; 95% CI, 0.89-3.24; P = .11) were associated with an increased risk of preterm birth. After additional adjustment for prenatal ΣDEHP or MHiNCH concentrations, the association of maternal preconception exposure to ΣDEHP and preterm birth remained robust (RR, 1.69; 95% CI, 1.17-2.44; P = .006), while the association of maternal preconception exposure to MHiNCH and preterm birth was attenuated (RR, 1.17; 95% CI, 0.49-2.81; P = .72). The remaining urinary metabolites examined in either parent showed no association with preterm birth.

CONCLUSIONS AND RELEVANCE

In this prospective cohort of subfertile couples, maternal preconception exposure to ΣDEHP metabolites was associated with an increased risk of preterm birth. The results suggest that female exposure to select phthalate plasticizers during the preconception period may be a potential risk factor for adverse pregnancy outcomes, which may need to be considered in preconception care strategies.

Diethylhexyl phthalate (DEHP) emission to indoor air and transfer to house dust from a PVC sheet

Diethylhexyl phthalate (DEHP) emission to air and transfer to house dust from a polyvinyl chloride (PVC) sheet were quantified for periods of 1, 3, 7, and 14 days using a passive flux sampler (PFS). Japanese Industrial Standards (JIS) test powders class 15 was used as the test house dust in settled weights of 0.3, 1, 3, and 12 mg/cm². DEHP concentrations in the surface air on the PVC sheet were estimated as 2.6-3.3 μg/m³ according to an emission test without dust. Although DEHP transfer rates from the PVC sheet to the house dust decreased over time, the adsorption did not reach an equilibrium state within 14 days. The transfer rates per dust weight increased with decreasing dust weight on the PVC sheet. The transfer rates per PVC sheet area increased nonlinearly with increasing dust weight on the PVC sheet. DEHP emission from a PVC sheet to air was one to three orders of magnitude lower than DEHP transfer from a PVC sheet to dust. In the case of 0.3 mg/cm² of settled house dust for 7 days, the emission rates to air were 35, 15, 9.1, 6.4, and 3.8 μg/m²/h for a diffusion distance of 0.90, 1.85, 2.75, 3.80, and 5.75 mm, respectively, and the transfer rate to dust was 5.3 × 10² μg/m²/h (no difference among the five diffusion distances). Compared to residents who clean the floor every day, exposure to DEHP in house dust could be 10 times higher for residents who clean the floor once every two weeks based on the time-weighted average concentrations in house dust.

Occurrence and human health risks of phthalates in indoor air of laboratories

Phthalate acid esters (PAEs) are of serious concern as a human health risk due to their ubiquitous presence in indoor air. In the present study, fifteen PAEs in the indoor air samples from physical, chemical, and biological laboratories in Guangzhou, southern China were analysed using gas chromatography mass spectrometry. Extremely high levels of PAEs of up to 6.39 × 10⁴ ng/m³ were detected in some laboratories. Diisobutyl phthalate (DiBP), di(methoxyethyl) phthalate (DMEP), and di-n-butyl phthalate (DBP) were the dominant PAEs with median levels of 0.48 × 10³, 0.44 × 10³, and 0.39 × 10³ ng/m³, respectively, followed by di-(2-propylheptyl) phthalate (DPHP) and di(2-ethylhexyl) phthlate (DEHP) (median levels: 0.16 × 10³ and 0.13 × 10³ ng/m³, respectively). DMEP and DPHP were found for the first time in indoor air. Principal component analysis indicated that profiles of PAEs varied greatly among laboratory types, suggesting notable variations in sources. The results of independent samples t-tests showed that levels of PAEs were significantly influenced by various environmental conditions. Both the non-carcinogenic and carcinogenic health risks from human exposure to PAEs based on the daily exposure dose in laboratory air were acceptable. Further research should be conducted to investigate the long-term health effects of exposure to PAEs in laboratories.

White matter microstructure mediates the association between prenatal exposure to phthalates and behavior problems in preschool children

BACKGROUND

Previous research reports associations between prenatal exposure to phthalates and childhood behavior problems; however, the neural mechanisms that may underlie these associations are relatively unexplored.

OBJECTIVE

This study examined microstructural white matter as a possible mediator of the associations between prenatal phthalate exposure and behavior problems in preschool-aged children.

METHODS

Data are from a subsample of a prospective pregnancy cohort, the Alberta Pregnancy Outcomes and Nutrition (APrON) study (n = 76). Mother-child pairs were included if mothers provided a second trimester urine sample, if the child completed a successful magnetic resonance imaging (MRI) scan at age 3-5 years, and if the Child Behavior Checklist was completed within 6 months of the MRI scan. Molar sums of high (HMWP) and low molecular weight phthalates (LMWP) were calculated from levels in urine samples. Associations between prenatal phthalate concentrations, fractional anisotropy (FA) and mean diffusivity (MD) in 10 major white matter tracts, and preschool behavior problems were investigated.

RESULTS

Maternal prenatal phthalate concentrations were associated with MD of the right inferior fronto-occipital fasciculus (IFO), right pyramidal fibers, left and right uncinate fasciculus (UF), and FA of the left inferior longitudinal fasciculus (ILF). Mediation analyses showed that prenatal exposure to HMWP was indirectly associated with Internalizing (path ab = 0.09, CI_.95 = 0.02, 0.20) and Externalizing Problems (path ab = 0.09, CI_.95 = 0.01, 0.19) through MD of the right IFO, and to Internalizing Problems (path ab = 0.11, CI_.95 = 0.01, 0.23) through MD of the right pyramidal fibers.

DISCUSSION

This study provides the first evidence of childhood neural correlates of prenatal phthalate exposure. Results suggest that prenatal phthalate exposure may be related to microstructural white matter in the IFO, pyramidal fibers, UF, and ILF. Further, MD of the right IFO and pyramidal fibers may transmit childhood risk for behavioral problems.