Prenatal exposure to mixtures of persistent endocrine disrupting chemicals and early menarche in a population-based cohort of British girls

Exposure of women undergoing In-Vitro Fertilization to per-and polyfluoroalkyl substances: Evidence on negative effects on Fertilization and high-quality embryos

In April 2023, the World Health Organization (WHO) reported that 17.5% of the global adult population experience infertility. What may be the contribution of per-and polyfluoroalkyl (PFAS) to this global public health problem? This study explored the associations between in vitro fertilization (IVF) outcomes and plasma concentrations of individual PFAS and PFAS mixtures in women undergoing in vitro fertilization and embryo transfer (IVF-ET) and how these exposures might affect IVF outcomes. We analyzed 8 PFASs in plasma samples from women (N=259) who underwent IVF treatment. In multivariable generalized linear mixed models, there were statistically significant associations of higher plasma concentrations of PFNA with reduced numbers of total retrieved oocytes [12.486 (95%CI:-0.446,25.418), p trend=0.017], 2PN zygotes [6.467(95%CI:-2.034,14.968), p trend=0.007], and cleavage embryos [6.039(95%CI:-2.162,14.240), p trend=0.008]. Similarly, there was a continuous decline in the numbers of retrieved 2PN zygotes and cleavage embryos with increasing concentration of PFOS [6.467(95%CI:-2.034,14.968), p trend=0.009 and 6.039(95%CI:-2.162,14.240), p trend=0.031,respectively] and a negative association between PFHxS concentrations and clinical pregnancy during the initial cycles of frozen ET [0.525(95%CI:0.410,0.640), p trend=0.021]. To investigate the joint effect of PFAS mixtures, a confounder-adjusted BKMR model analysis showed inverse relationship between PFAS mixtures and the number of high-quality embryos, 2PN zygotes and cleavage embryos, to which the greatest contributors to the mixture effect are PFDeA and PFBS, respectively. It demonstrated that PFAS exposure might exert negative effects on oocyte yield, fertilization and high-quality embryo in women undergoing IVF. These findings suggest that exposure to PFAS may increase the risk of female infertility and further studies are needed to uncover the potential mechanisms underlying the reproductive effects associated with PFAS.

Endocrine Disruptors and Metabolic Changes: Impact on Puberty Control

OBJECTIVE

This study aims to explore the significant impact of environmental chemicals on disease development, focusing on their role in developing metabolic and endocrine diseases. The objective is to understand how these chemicals contribute to the increasing prevalence of precocious puberty, considering various factors, including epigenetic changes, lifestyle, and emotional disturbances.

METHODS

The study employs a comprehensive review of descriptive observational studies in both human and animal models to identify a degree of causality between exposure to environmental chemicals and disease development, specifically focusing on endocrine disruption. Due to ethical constraints, direct causation studies in human subjects are not feasible; therefore, the research relies on accumulated observational data.

RESULTS

Puberty is a crucial life period with marked physiological and psychological changes. The age at which sexual characteristics develop is changing in many regions. The findings indicate a correlation between exposure to endocrine-disrupting chemicals and the early onset of puberty. These chemicals have been shown to interfere with normal hormonal processes, particularly during critical developmental stages such as adolescence. The research also highlights the interaction of these chemical exposures with other factors, including nutritional history, social and lifestyle changes, and emotional stress, which together contribute to the prevalence of precocious puberty.

CONCLUSION

Environmental chemicals significantly contribute to the development of certain metabolic and endocrine diseases, particularly in the rising incidence of precocious puberty. Although the evidence is mainly observational, it adequately justifies regulatory actions to reduce exposure risks. Furthermore, these findings highlight the urgent need for more research on the epigenetic effects of these chemicals and their wider impact on human health, especially during vital developmental periods.

Postnatal Exposure to the Endocrine Disruptor Dichlorodiphenyltrichloroethane Affects Adrenomedullary Chromaffin Cell Physiology and Alters the Balance of Mechanisms Underlying Cell Renewal

Dichlorodiphenyltrichloroethane (DDT) is a wide-spread systemic pollutant with endocrine disrupting properties. Prenatal exposure to low doses of DDT has been shown to affect adrenal medulla growth and function. The role of postnatal exposure to DDT in developmental disorders remains unclear. The aim of the present investigation is to assess growth parameters and the expression of factors mediating the function and renewal of chromaffin cells in the adult adrenal medulla of male Wistar rats exposed to the endocrine disruptor o,p'-DDT since birth until sexual maturation. The DDT-exposed rats exhibited normal growth of the adrenal medulla but significantly decreased tyrosine hydroxylase production by chromaffin cells during postnatal period. Unlike the control, the exposed rats showed enhanced proliferation and reduced expression of nuclear β-catenin, transcription factor Oct4, and ligand of Sonic hedgehog after termination of the adrenal growth period. No expression of pluripotency marker Sox2 and absence of Ascl 1-positive progenitors were found in the adrenal medulla during postnatal ontogeny of the exposed and the control rats. The present findings indicate that an increase in proliferative activity and inhibition of the formation of reserve for chromaffin cell renewal, two main mechanisms for cell maintenance in adrenal medulla, in the adult DDT-exposed rats may reflect a compensatory reaction aimed at the restoration of catecholamine production levels. The increased proliferation of chromaffin cells in adults suggests excessive growth of the adrenal medulla. Thus, postnatal exposure to DDT alters cell physiology and increases the risk of functional insufficiency and hyperplasia of the adrenal medulla.

Systematic evidence mapping informs a class-based approach to assessing personal care products and pubertal timing

BACKGROUND

Personal care products (PCPs) contain many different compounds and are a source of exposure to endocrine disrupting chemicals (EDCs), including phthalates and phenols. Early-life exposure to EDCs commonly found in PCPs has been linked to earlier onset of puberty.

OBJECTIVE

To characterize the human and animal evidence on the association between puberty-related outcomes and exposure to PCPs and their chemical constituents and, if there is sufficient evidence, identify groups of chemicals and outcomes to support a systematic review for a class-based hazard or risk assessment.

METHODS

We followed the OHAT systematic review framework to characterize the human and animal evidence on the association between puberty-related health outcomes and exposure to PCPs and their chemical constituents.

RESULTS

Ninety-eight human and 299 animal studies that evaluated a total of 96 different chemicals were identified and mapped by key concepts including chemical class, data stream, and puberty-related health outcome. Among these studies, phthalates and phenols were the most well-studied chemical classes. Most of the phthalate and phenol studies examined secondary sex characteristics and changes in estradiol and testosterone levels. Studies evaluating PCP use and other chemical classes (e.g., parabens) had less data.

CONCLUSIONS

This systematic evidence map identified and mapped the published research evaluating the association between exposure to PCPs and their chemical constituents and puberty-related health outcomes. The resulting interactive visualization allows researchers to make evidence-based decisions on the available research by enabling them to search, sort, and filter the literature base of puberty-related studies by key concepts. This map can be used by researchers and regulators to prioritize and target future research and funding to reduce uncertainties and address data gaps. It also provides information to inform a class-based hazard or risk assessment on the association between phthalate and phenol exposures and puberty-related health outcomes.

Review of scientific literature on available methods of assessing organochlorine pesticides in the environment

Organochlorine pesticides (OCPs) are persistent organic pollutants (POPs) widely used in agriculture and industry, causing serious health and ecological consequences upon exposure. This review offers a thorough overview of OCPs analysis emphasizing the necessity of ongoing work to enhance the identification and monitoring of these POPs in environmental and human samples. The benefits and drawbacks of the various OCPs analysis techniques including gas chromatography-mass spectrometry (GC-MS), gas chromatography-electron capture detector (GC-ECD), and liquid chromatography-mass spectrometry (LC-MS) are discussed. Challenges associated with validation and optimization criteria, including accuracy, precision, limit of detection (LOD), and limit of quantitation (LOQ), must be met for a method to be regarded as accurate and reliable. Suitable quality control measures, such as method blanks and procedural blanks, are emphasized. The LOD and LOQ are critical quality control measure for efficient quantification of these compounds, and researchers have explored various techniques for their calculation. Matrix interference, solubility, volatility, and partition coefficient influence OCPs occurrences and are discussed in this review. Validation experiments, as stated by European Commission in document SANTE/11813/2017, showed that the acceptance criteria for method validation of OCP analytes include ≤20 % for high precision, and 70-120 % for recovery. This may ultimately be vital for determining the human health risk effects of exposure to OCP and for formulating sensible environmental and public health regulations.

Association between exposure to persistent organic pollutants and pubertal timing in boys and girls: A systematic review and meta-analysis

In recent years, the phenomenon of abnormal pubertal timing in children has become increasingly common worldwide. Persistent organic pollutants (POPs) may be one of the risk factors contributing to this phenomenon, but the relationship between them is unclear based on current evidence. The purpose of this study was to determine the association of POPs exposure with pubertal timing in girls and boys by conducting a systematic review and meta-analysis. We searched PubMed and Embase databases for studies before June 1, 2023. Meta-analysis was performed by pooling relative risk (RR) or odds ratio (OR) or prevalence ratio (PR) or hazard ratio (HR) estimates with 95 % confidence intervals (CIs). Subgroup analysis, publication bias assessment and sensitivity analysis were also carried out. A total of 21 studies were included, involving 2479 boys and 8718 girls. The results of meta-analysis showed that exposure to POPs was significantly associated with delayed pubertal timing in girls (RR: 0.85; 95 % CI: 0.79-0.91; p < 0.001). There was no statistically significant association between exposure to POPs and pubertal timing in boys (RR: 1.18; 95 % CI: 0.99-1.40; p = 0.070). Subgroup analysis showed that there may be gender differences in the effects of exposure to POPs on pubertal timing. Our results suggested that exposure to POPs could delay pubertal timing in girls. However, based on current evidence, no significant association was found between POPs exposure and pubertal timing in boys.

The Long-Term Effect of Maternal Iron Levels in the Second Trimester on Mild Thinness among Preschoolers: The Modifying Effect of Small for Gestational Age

The supplementation of multiple micronutrients throughout pregnancy can reduce the risk of adverse birth outcomes and various diseases in children. However, the long-term effect of maternal multiple micronutrient levels in the second trimester on the overall development of preschoolers remains unknown. Therefore, 1017 singleton mother-infant pairs and 6-year-old preschoolers were recruited based on the China-Wuxi Birth Cohort Study. Meanwhile, information on the demographic characteristics of pregnant women and preschoolers, maternal copper, calcium, iron, magnesium, and zinc levels in whole blood during the second trimester, and neonatal outcomes, were collected. We aimed to investigate the long-term impact of maternal copper, calcium, iron, magnesium, and zinc levels in the second trimester on mild thinness among 6-year-old preschoolers, and the modifying effect of small for gestational age (SGA), within the Chinese population. Multiple logistic regression models revealed that high-level maternal iron in the second trimester reduced the risk of mild thinness [adjusted OR: 0.46 (95% CI: 0.26, 0.80)] among 6-year-old preschoolers. However, no significant association was found for the remaining four maternal essential metal elements. Additionally, the restricted cubic spline function showed that the risk of mild thinness decreased when maternal iron concentration exceeded 7.47 mmol/L in whole blood during the second trimester. Furthermore, subgroup analysis indicated that the long-term protective effect of high-level maternal iron on mild thinness was only observed in SGA infants. Summarily, high-level maternal iron in the second trimester distinctly lowers the risk of mild thinness among 6-year-old preschoolers, especially in preschoolers with birth outcomes of SGA. Our findings offer evidence for the implementation of iron supplementation in the second trimester as a preventive measure against mild thinness in children.

Exposure to Perfluoroalkyl Substances and Associations with Pubertal Onset and Serum Reproductive Hormones in a Longitudinal Study of Young Girls in Greater Cincinnati and the San Francisco Bay Area

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS), endocrine disrupting chemicals with worldwide exposure, cause changes in mammary gland development in rodents. A few human studies report delay in pubertal events with increasing perfluorooctanoic acid (PFOA) exposure, but to our knowledge none have examined reproductive hormone levels at thelarche.

METHODS

In a cohort of Greater Cincinnati (GC) and San Francisco Bay Area (SFBA) girls recruited at 6-8 years of age, clinical examinations were conducted annually or semiannually with sequential Tanner staging. PFAS concentrations were measured in the first serum sample of 704 girls. In 304 GC girls, estradiol (E 2 ), estrone (E 1 ), testosterone (T), and dihydroepiandrosterone sulfate (DHEAS) were measured in serum at four time points around puberty. Relationships between PFAS and age at thelarche, pubarche, and menarche were analyzed using survival and structural equation models. The association between PFAS and reproductive hormones was assessed using linear regression models.

RESULTS

Median PFOA serum concentrations in GC (N = 353 , 7.3  ng / mL ) and the SFBA (N = 351 , 5.8  ng / mL ) were higher than in the U.S.

POPULATION

In multivariable Cox proportional hazard models [adjusted for race, body mass index (BMI)], increasing serum log-transformed PFOA was associated with a delay in pubarche [hazard ratio  ( HR ) = 0.83 ; 95% CI: 0.70, 0.99] and menarche (HR = 0.04 ; 95% CI: 0.01, 0.25). Structural equation models indicated a triangular relationship between PFOA, BMI percentile, and the age at the pubertal milestone. Increased PFOA had a statistically significant direct effect of delay on all three milestones, as did BMI. Perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDeA), and 2-(N -methyl-perfluorooctane sulfonamido) acetic acid (Me-PFOSA-AcOH) also were associated with later thelarche, and Me-PFOSA-AcOH also with later pubarche. PFOA was inversely associated with DHEAS (p < 0.01 ), E 1 (p = 0.04 ), and T (p = 0.03 ) concentrations at 6 months prior to puberty.

CONCLUSIONS

PFAS may delay pubertal onset through the intervening effects on BMI and reproductive hormones. The decreases in DHEAS and E 1 associated with PFOA represent biological biomarkers of effect consistent with the delay in onset of puberty. https://doi.org/10.1289/EHP11811.

PFAS and Phthalate/DINCH Exposure in Association with Age at Menarche in Teenagers of the HBM4EU Aligned Studies

Early puberty has been found to be associated with adverse health outcomes such as metabolic and cardiovascular diseases and hormone-dependent cancers. The decrease in age at menarche observed during the past decades has been linked to an increased exposure to endocrine-disrupting compounds (EDCs). Evidence for the association between PFAS and phthalate exposure and menarche onset, however, is inconsistent. We studied the association between PFAS and phthalate/DINCH exposure and age at menarche using data of 514 teenagers (12 to 18 years) from four aligned studies of the Human Biomonitoring for Europe initiative (HBM4EU): Riksmaten Adolescents 2016-2017 (Sweden), PCB cohort (follow-up; Slovakia), GerES V-sub (Germany), and FLEHS IV (Belgium). PFAS concentrations were measured in blood, and phthalate/DINCH concentrations in urine. We assessed the role of each individual pollutant within the context of the others, by using different multi-pollutant approaches, adjusting for age, age- and sex-standardized body mass index z-score and household educational level. Exposure to di(2-ethylhexyl) phthalate (DEHP), especially mono(2-ethyl-5-hydroxyhexyl) phthalate (5OH-MEHP), was associated with an earlier age at menarche, with estimates per interquartile fold change in 5OH-MEHP ranging from -0.34 to -0.12 years in the different models. Findings from this study indicated associations between age at menarche and some specific EDCs at concentrations detected in the general European population, but due to the study design (menarche onset preceded the chemical measurements), caution is needed in the interpretation of causality.

Impact of Chemicals on the Age of Menarche: A Literature Review

A growing body of evidence suggests that chemicals interfere with the age of onset of menarche. We conducted a review in order to demonstrate the relationship between several categories of chemicals and menarche. We searched for English language papers using the Medline/PubMed database until April 2023. The chemical factors found to affect menarche were prenatal and antenatal smoke, phthalates, phenols, organochlorines, perfluoroalkyls and polyfluoroalkyls, metals, air pollutants and polybrominated diphenyl ethers. Low or high exposure to each chemical compound could affect the age of menarche, leading to early or delayed menarche. Furthermore, the results show that intrauterine exposure may have a different impact from antenatal exposure. There is evidence that endocrine-disrupting chemicals affect the age of menarche, but more research needs to be conducted.

Associations between exposure to a mixture of perfluoroalkyl and polyfluoroalkyl substances and age at menarche in adolescent girls utilizing three statistical models

Exposure to perfluoroalkyl and polyfluoroalkyl substances (PFAS) is suggested to interfere with endocrine function and may affect female pubertal development. However, the epidemiological evidence on age at menarche associated with PFAS exposure is still inconsistent. Our objective was to investigate association of serum PFAS concentrations with age at menarche among 12-19 years old girls. We used data on 432 girls from National Health and Nutrition Examination Survey (NHANES) 2007-2012 cycles. NHANES reported serum concentrations of perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), perfluorohexane sulfonate (PFHxS), perfluorononanoic acid (PFNA) and perfluorodecanoic acid (PFDA) as quantified by liquid chromatography tandem mass spectrometry (LC-MS/MS). Age at menarche was self-reported by girls or their guardians. Multivariable linear regression models were applied to estimate the association of individual PFAS exposure with age at menarche. The combined effects of PFAS mixture exposures on age at menarche were assessed using three statistical methods, including Bayesian kernel machine regression (BKMR), weighted quantile sum regression (WQS), and elastic net regression (ENR). In the single-chemical model, girls in the middle tertile of serum PFOA concentration had a lower age at menarche [regression coefficient (β) = -0.73 years, 95% confidence interval (CI): 1.44, -0.01; P = 0.047], compared with those in the lower tertile. Girls in the higher tertile of PFNA exposure were associated with older age at menarche (β = 0.36 years, 95% CI: 0.03, 0.80; P = 0.027), compared with those in the lower tertile. In the multiple-chemical models using BKMR and ENR approaches, higher PFNA exposure was significantly associated with older age at menarche among girls, after adjusting for other PFAS. We found suggestive evidence that higher PFAS mixture exposures may be related to an increase in age at menarche using the BKMR model. In conclusion, exposure to PFNA was associated with the later timing of menarche among girls.

Effects of Ambient Air Pollution on Precocious Puberty: A Case-Crossover Analysis in Nanjing, China

BACKGROUND

Ambient air pollution is closely related to a variety of health outcomes. Few studies have focused on the correlations between air pollution exposure and children's sexual development. In this study, we investigated the potential effects of exposure to air pollution on precocious puberty among children using real-world evidence.

METHODS

We conducted a case-crossover study (n = 2201) to investigate the effect of ambient air pollution exposure on precocious puberty from January 2016 to December 2021. Average exposure levels of PM_2.5, PM₁₀, SO₂, NO₂, CO, and O₃ before diagnosis were calculated by using the inverse distance weighting (IDW) method. Distributed lag nonlinear model (DLNM) was used to assess the effect of air pollutants exposure on precocious puberty.

RESULTS

The mean age of the children who were diagnosed with precocious puberty was 7.47 ± 1.24 years. The average concentration of PM_2.5 and PM₁₀ were 38.81 ± 26.36 μg/m³ and 69.77 ± 41.07 μg/m³, respectively. We found that exposure to high concentrations of PM_2.5 and PM₁₀ might increase the risk of precocious puberty using the DLNM model adjusted for the age, SO₂, NO₂, CO, and O₃ levels. The strongest effects of the PM_2.5 and PM₁₀ on precocious puberty were observed in lag 27 (OR = 1.72, 95% CI: 1.01-2.92) and lag 16 (OR = 1.95, 95% CI: 1.33-2.85), respectively.

CONCLUSION

Our findings supported that short-term exposure to air pollution was the risk factor for precocious puberty. Every effort should be made to protect children from air pollution.

Birth outcomes associated with paternal polybrominated and polychlorinated biphenyl exposure

In 1973-74, a polybrominated biphenyl (PBB) flame retardant mixture was shipped to Michigan livestock feed mills in place of a nutritional supplement and contaminated the food supply. Following the accident, the Michigan PBB Registry was established to study the long-term health effects of halogenated compounds and is now led by a community-academic partnership. PBB exposure is associated with altered DNA methylation in sperm, which may lead to adverse birth outcomes in children whose fathers have increased levels of serum PBB or polychlorinated biphenyl (PCB). Paternal PBB and PCB levels of men enrolled in the Michigan PBB Registry (n = 155) were analyzed against matched offspring birthweight and gestational age (n = 336). Birthweight and gestational age were dichotomized at the 25th percentile and 37 weeks, respectively, and paternal PBB and PCB levels were examined as continuous measures and divided into tertiles. Associations of offspring birthweight and gestational age with paternal PBB and PCB serum concentrations were modeled using multivariable linear spline and log-risk regression, adjusting for family clustering, paternal health and lifestyle factors, maternal PBB, and PCB serum concentrations, sex, and offspring gestational age (for birthweight). Fathers in the middle and upper PBB and PCB tertiles had increased risks for lowest quartile birthweight compared to the first tertile, with adjusted risk ratios (aRR) = 1.67 (95% CI: 0.93, 2.99) and aRR = 2.06 (95% CI: 1.12, 3.79) for PBB, and aRR = 1.47 (95% CI: 0.79, 2.75) and aRR = 1.34 (95% CI: 0.70, 2.54) for PCB, respectively. Elevated paternal PBB levels were not associated with an increased risk for preterm birth, while PCB levels were associated with a small, but not significant, decrease in gestational age, β = -0.37 (95% CI: -0.76, 0.03) weeks per log unit increase PCB. The findings suggest that increased paternal PBB and PCB levels negatively impact offspring birthweight, and paternal PCB levels may negatively impact gestational age.

A multipollutant low-grade exposure regulates the expression of miR-30b, Let-7a and miR-223 in maternal sera: Evidence from the NEHO cohort

There is growing evidence that environmental pollutants can induce epigenetic modifications altering the balance of miRNAs and inducing the onset of pathological conditions in animals. In this study, we measured the serum concentration of a suite of inorganic and organic pollutants (Cu, Zn, Se, Hg, HCB, p,p'-DDE, PCBs) and their association to serum miR-30b, miR-223 and Let-7a microRNA expression in 68 healthy pregnant women from the NEHO birth cohort sited in a highly industrialized area. The effects of the pollutants on the modulation of circulating miRNAs' expression were first investigated using linear continuous regression models with a single-compound approach showing that miR-223 expression was significantly associated with serum concentration of Se and Zn (pSe = 0.0336; pZn = 0.0225) and miR-30b was associated with Hg levels (pHg = 0.019). Furthermore, when contaminants were categorized into tertiles, miR-223 and miR-30b showed a positive association with higher tertiles of Zn, p,p'-DDE (pZn = 0.023; pDDE = 0.041) and Hg (pHg = 0.008), respectively. Moreover, Let-7a expression was exclusively influenced by medium tertiles levels of Se (low vs medium tertiles, p = 0.001). Simultaneous exposure to multi-pollutant mixture was approached by WQS regression model. Statistical analysis shows a driving effect of Zn, Se, Cu, Hg and HCB on significant increased expression of Let-7a (p = 0.045). Mercury and Se significantly amplified the expression for miR-30b (p = 0.038). Differently, the combined effect of p,p'-DDE, Zn and Se decreased miR-223 expression (p = 0.0001). The documented modified expression of circulating miRNAs in the serum of pregnant women, exposed to low-medium dose contaminants mixtures offers innovative early-warning approaches to human health risk assessment.

Per- and polyfluoroalkyl substances (PFAS) exposure in women seeking in vitro fertilization-embryo transfer treatment (IVF-ET) in China: Blood-follicular transfer and associations with IVF-ET outcomes

As follicular fluid constitutes a critical microenvironment for the development of oocytes, investigation of environmental contaminants in follicular fluid may facilitate a better understanding of the influence of environmental exposure on reproductive health. In the present study, we aimed to investigate per- and polyfluoroalkyl substances (PFAS) exposure in women receiving in vitro fertilization-embryo transfer (IVF-ET) treatment, determine the blood-follicle transfer efficiencies (BFTE) of PFAS, and explore potential associations between PFAS exposure and selected IVF-ET outcomes. Our results revealed that n-PFOA was the most abundant PFAS in both serum and follicular fluid (FF) (median = 5.85 and 5.56 ng/mL, respectively), followed by n-PFOS (4.95 and 4.28 ng/mL), 6:2 Cl-PFESA (2.18 and 2.10 ng/mL), PFNA (1.37 and 1.37 ng/mL), PFUdA (0.33 and 0.97 ng/mL), PFDA (0.37 and 0.66 ng/mL), PFHxS (0.42 and 0.39 ng/mL), and PFHpS (0.11 and 0.10 ng/mL). The median BFTE ranged from 0.65 to 0.92 for individual PFAS, indicating a relatively high tendency of PFAS to cross the blood-follicle barrier (BFB). An inverted V-shaped trend was observed between the median BFTE and the number of fluorinated carbon atoms or the log K_ow (octanol-water partition coefficient) for individual PFAS, suggesting the influence by physicochemical properties and molecular structures. Although our data did not find any clear pattern in the link between blood or follicular fluid concentrations of PFAS and selected IVF-ET outcomes, our study raises the need for better characterization of exposure to environmental chemicals in follicular fluid together with its potential influence on reproductive health.

New insights on the effects of endocrine-disrupting chemicals on children

OBJECTIVE

Endocrine disrupting chemicals (EDCs) are present in many areas and materials of the common life, and exposure to these chemicals can occur from products to personal care, from air and food. This review aims to summarize the more recent epidemiological findings for the impact of EDCs on endocrine system health in children, including effects in growth, metabolism, sexual development, and reproduction.

SOURCES

The MEDLINE database (PubMed) was searched on August 24th, 2021, filtering for EDCs, endocrine disruptors, children, and humans.

SUMMARY OF THE FINDINGS

Intrauterine exposure of EDCs can have transgenerational effects, thus laying the foundation for disease in later life. The dose-response relationship may not always be predictable as even low-level exposures that may occur in everyday life can have significant effects on a susceptible individual. Although individual compounds have been studied in detail, the effects of a combination of these chemicals are yet to be studied to understand the real-life situation where human beings are exposed to a "cocktail effect" of these EDCs. Epidemiological studies in humans suggest EDCs' effects on prenatal growth, thyroid function, glucose metabolism, obesity, puberty, and fertility mainly through epigenetic mechanisms.

CONCLUSIONS

EDCs cause adverse effects in animals, and their effects on human health are now known and irrefutable. Because people are typically exposed to multiple endocrine disruptors, assessing public health effects is difficult. Legislation to ban EDCs and protect especially pregnant women and young children is required and needs to be revised and adjusted to new developments on a regular basis.

Identifying Environmental Endocrine Disruptors Associated With the Age at Menarche by Integrating a Transcriptome-Wide Association Study With Chemical-Gene-Interaction Analysis

Menarche is the first occurrence of menstrual bleeding and one of the most important events of female puberty. Alarmingly, over the last several decades, the mean age at menarche (AAM) has decreased. Environmental endocrine disruptors (EEDs) are chemicals that may interfere with the endocrine system, resulting in adverse developmental, immunological, neurological, and reproductive effects in humans. Thus, the effects of EEDs on fertility and reproduction are growing concerns in modern societies. In this study, we aimed to determine the influence of genetic and environmental factors on AAM. We used data from an AAM genome-wide association study of 329,345 women to conduct a transcriptome-wide association study (TWAS) with FUSION software. As references, we determined the gene-expression levels in the hypothalamus, pituitary gland, ovaries, uterus, and whole blood. We performed Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses using the significantly dysregulated genes identified by the TWAS. Using the STRING database, we also generated a protein-protein-interaction network to analyze common AAM-specific genes identified by the TWAS with different tissues. We performed chemical-related gene set enrichment analysis (CGSEA) and identified significant TWAS genes to uncover relationships between different chemicals and AAM. The TWAS identified 9,848 genes; among these, 1580 genes were significant (P < 0.05), and 11 genes were significant among the hypothalamus, pituitary, ovary, uterus, and whole blood. CGSEA identified 1,634 chemicals, including 120 chemicals significantly correlated with AAM. In summary, we performed a TWAS (for genetic factors) and CGSEA (for environmental factors) focusing on AAM and identified several AAM-associated genes and EEDs. The results of this study expand our understanding of genetic and environmental factors related to the onset of female puberty.

Endocrine-disrupting chemicals in a typical urbanized bay of Yellow Sea, China: Distribution, risk assessment, and identification of priority pollutants

Endocrine-disrupting chemicals (EDCs) in water are receiving particular attention as they pose adverse effects on aquatic systems, even at trace concentrations. A comprehensive study was conducted on 14 EDCs (five estrogens and nine household and personal care products (HPCPs)) in the water of the urbanized Jiaozhou Bay in the Yellow Sea during summer and winter. Results showed that the total concentration of 14 EDCs ranged from 100 to 658 ng L^-1 and 56.7-212 ng L^-1 in the estuarine and bay water, respectively. The average total concentration of five estrogens in summer was significantly (p < 0.05) lower than that in winter due to the higher precipitation dilution and degradations during summer, whereas the average total concentration of nine HPCPs was significantly (p < 0.05) higher during the summer than that during the winter because of the higher usage and emissions during the summer. Estrogens and HPCPs were dominated by 17α-ethinylestradiol and p-hydroxybenzoic acid (PHBA), respectively. High PHBA concentrations may be related to the hydrolysis of parabens. The total concentrations of EDCs were higher in the eastern coastal seawater of the bay due to the strong influence of domestic and industrial wastewater discharge. Estrogens may interfere with the endocrine system of aquatic organisms in the bay because the total estradiol equivalent concentration exceeded 1 ng L^-1. 17α-ethinylestradiol was the main contributor to the estrogenic activity. The EDC mixtures posed high risks (RQ > 1) to mollusks, crustaceans, and fish, and low to moderate risks (RQ < 1) to algae. Fish was the most sensitive aquatic taxon to the EDC mixtures. Given the concentration and frequency of EDCs, the optimized risk quotient method revealed that 17α-ethinylestradiol, estrone, triclocarban, triclosan, and 17β-estradiol should be prioritized in ecological management because of their high risks (prioritization index of >1).

Hair determination of per- and polyfluoroalkyl substances (PFAS) in the Italian population

Per- and polyfluoroalkyl substances (PFAS) are anthropogenic chemicals present in the environment and defined as persistent organic pollutants (POPs). The interest in these forms of contaminants is related to the toxic consequences for health derived from exposures and bioaccumulation processes. The present research aims at assessing differences in the exposure of PFAS in the Italian population by hair analyses. To this aim, 20 compounds of the PFAS family were investigated in hair of 86 Italian subjects distributed across the regions of Veneto, Emilia-Romagna, Lombardy and Marche. The applied method was ad hoc developed in a previous research and included SPE extraction and LC-QTOF analysis. In the analyzed population, 66.4 % had quantifiable amounts of one or more PFAS molecules (up to 4 compounds); mean PFAS content, expressed as sum of PFAS, was 0.1457 ng/g, ranging from "not detected" to 0.85 ng/g (SD 0.1867). PFOA and PFOS were the chemicals most frequently detected, with mean concentrations of 0.1402 ng/g and 0.1155 ng/g, respectively. PFBA was detected in 9.3 % of subjects with a mean concentration of 0.3760 ng/g; PFNA in 3.5 % of subjects with mean concentration 0.12 ng/g; PFDA was found in one subject at the concentration of 0.541 ng/g. PFUnA and PFHxS were detected below the limit of quantification. The overall results displayed differences in the presence and prevalence of PFAS in hair of the Italian population on a geographical base. On the contrary, no significatively differences in the amount of PFAS were observed when considering gender or age classes. On this base, hair can be considered a good diagnostic tool to assess PFAS exposure on a regional-scaled base. Of course, more studies are required to infer PFAS internal dose from hair results due to its peculiar detection window and to interpretative issues derived from external contamination.

Early-Life Exposure to Per- and Poly-Fluorinated Alkyl Substances and Growth, Adiposity, and Puberty in Children: A Systematic Review

Per- or polyfluoroalkyl substances (PFAS), a family of synthetic polyfluorinated compounds, are widely used in consumer products. Ubiquitous exposures to PFAS, in consideration of their persistence, bioaccumulation potential, and toxicities have led to concerns regarding possible harmful effects during critical periods of development in early-life and long-term consequences on health. The potential effects of PFAS depend on various factors including the type of PFAS and the timing and level of exposure. We performed a systematic review of the epidemiologic literature to assess the effects of early-life PFAS exposure on prenatal and postnatal growth, adiposity, and puberty in children and adolescents. For birth size, most studies indicated that prenatal PFAS exposure, in particular long-chain PFAS, may impair fetal growth, albeit some reports of null associations with maternal PFAS. For growth within 2 years of age, prenatal PFAS exposure showed no associations with height and either null or negative associations with weight. However, postnatal PFAS exposures were inversely related to height and weight at 2 years in a cross-sectional study. For postnatal adiposity, prenatal PFAS may mostly have negative associations with body mass index in the first 2 years of life, but positive relationships with adiposity in childhood and adolescence, although some studies showed null associations. For puberty, the evidence for associations between early-life PFAS exposure and pubertal development or sex hormone levels were limited and inconclusive. From experimental studies, plausible mechanisms through which PFAS may affect early-life growth and puberty include PFAS-induced activation of peroxisome proliferator-activated receptor, alterations of thyroid or steroid hormone synthesis and metabolism, and their weak estrogenic or anti-androgenic properties. Although the published literature suggests possible effects of PFAS exposures on early-life growth, adiposity, and puberty, current human evidence is limited in establishing PFAS-induced effects on early-life physical development. Further investigation is warranted to clarify PFAS-induced effects on growth and physical development in consideration of the critical time-window of exposure, concomitant exposure to chemical mixtures including various PFAS types, and possible non-monotonic dose-response relationship for growth and adiposity trajectories.