Association between bisphenol a exposure and idiopathic central precocious puberty (ICPP) among school-aged girls in Shanghai, China

The relationship between bisphenol A and phthalates with precocious puberty in Vietnamese children

OBJECTIVES

This study is aimed to explore the correlation between bisphenol A (BPA) and phthalates, including diethylhexylphthalate (DEHP) and dibutylphthalate (DBP), and precocious puberty (PP).

METHODS

A case-control study was conducted in Ho Chi Minh City, Vietnam, from November 2021 to April 2022, involving 250 children, with 124 of them diagnosed with PP and 126 serving as controls. We assessed the levels of urinary BPA, DEHP, and DBP in all participants and examined their association with the risk of PP.

RESULTS

BPA was detected in 11.3 % of PP cases but was not found in any individuals in the control group (p<0.001). Diethylhexylphthalate metabolite (MEHP) was not detected in any of the samples. Positive urinary results for dibutylphthalate metabolite (MBP) were observed in 8.1 % of PP cases and 2.4 % in the control group, with an odds ratio of 3.6 (95 % confidence interval: 0.97-13.4, p=0.03).

CONCLUSIONS

The PP group exhibited a higher prevalence of positive urinary BPA and DBP levels compared to the control group.

Bisphenol AF exposure synergistically increases the risk for suicidality among early adolescents with child maltreatment: A prospective cohort study

BACKGROUND

Child maltreatment (CM) is correlated with suicidality risk among adolescents. Additionally, exposure to bisphenol AF (BPAF) may increase this risk. However, the combined effect of CM and BPAF exposure remains unknown and should be further investigated.

METHODS

In this study, 1,475 early adolescents (mean age = 12.48 years) from the Chinese Early Adolescents Cohort were enrolled. Data were collected at three time points with an interval of 12 months between 2019 and 2021. Participants' history of CM and suicidality (including suicidal ideation and suicidal attempts) were evaluated using a self-report questionnaire. Blood samples were obtained from participants to measure serum BPAF concentrations at baseline. Group-based trajectory modeling was employed to identify different developmental trajectories of suicidality across the three waves. After adjusting for potential confounders, the association between CM and BPAF exposure on suicidal ideation and suicidal attempts was assessed using logistic regression and Poisson regression analyses.

RESULTS

Participants with CM were associated with a risk of one- and two-year incident suicidality (all ps < 0.05), and BPAF levels were positively associated with two-year incident suicidal ideation (adjusted OR = 1.68, 95% CI: 1.13-2.50). Additionally, middle and high levels of BPAF exposure synergistically increase the risk for one- and two-year incident suicidal ideation among participants with CM (adjusted ORs = 2.00-3.83). Similarly, participants exposed to high-level BPAF as well as CM were at a greater risk of one- and two-year incident suicidal attempts than those with low-level BPAF exposure and no CM (adjusted incidence rate ratio [IRRs] = 2.82-4.34). Moreover, compared with participants with a low developmental trajectory of suicidality across the three waves, high BPAF exposure exhibited a significant synergistic effect on participants with CM in the persistently high suicidal ideation trajectory and the increasing suicidal attempts trajectory (all ps < 0.05). Sex subgroup analysis revealed that females were more susceptible to the synergistic effect of BPAF and CM exposure on suicidality than males.

CONCLUSIONS

Environmental factors and the psychological status of individuals may synergistically increase their susceptibility to suicidality. These results offer novel insights into enhancing our understanding of suicidality among adolescents.

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.

Dietary pattern and precocious puberty risk in Chinese girls: a case-control study

BACKGROUND

The role of dietary intake on precocious puberty remains unclear. This study aimed to investigate the association between the amount and frequency of dietary intake and the risk of precocious puberty in Chinese girls.

METHODS

In this case-control study, we enrolled 185 precocious puberty girls and 185 age-matched controls. Their dietary intake was assessed through a semi-quantitative food frequency questionnaire. Their sociodemographic and lifestyle data were collected. The associations between dietary intake and risk of precocious puberty were assessed by conditional logistic regression models.

RESULTS

After multivariate adjustment, consuming a higher amount of red meat was associated with higher precocious puberty risk (OR = 2.74, 95% CI: 1.25-6.02), while a higher frequency of fruit ( P for trend = 0.024) and amount of vegetable intake was associated with a lower risk of precocious puberty (P for trend = 0.002). The high vegetable and protein dietary pattern was significantly negatively associated with precocious puberty (OR = 0.78, 95% CI: 0.63-0.97), whereas the high animal food and fruits dietary pattern was remarkably positively associated with precocious puberty (OR = 1.36, 95% CI: 1.09-1.69), after adjusting for age and body mass index.

CONCLUSIONS

High vegetable and protein dietary pattern is a protective factor against precocious puberty, while high animal food and fruits dietary pattern is a risk factor for precocious puberty in Chinese girls. Attentions should be paid to a reasonable intake of red meat, eggs, and fruits in children's daily diet, increase their intake of vegetables, in order to reduce the risk of precocious puberty.

Association between Urinary BPA Substitutes and Precocious Puberty among Girls: A Single-Exposure and Mixed Exposure Approach from a Chinese Case-Control Study

There is an argument that BPA substitutes may have the same or more deleterious health effects as BPA due to their structural similarity. This study explored the association between urinary BPA substitutes and precocious puberty among girls by including 120 girls with precocious puberty (cases) aged 2-10 years enrolled at Nanjing Children's Hospital Department of Endocrinology in China between April 2021 to September 2021 and 145 healthy girls (controls) recruited from a primary school. Logistic regression was used to evaluate the effect of single exposures, and Bayesian kernel machine regression (BKMR) and quantile-based g-computation were used for the mixed effect. In the multivariate logistic regression, BPS (bisphenol S), TBBPA (tetrabromobisphenol A), and BPFL (bisphenol-FL) were significantly associated with increased risk of precocious puberty (odds ratio (OR) = 1.75, 95% confidence interval (CI): 1.13, 2.76, p = 0.014), (OR = 1.46, CI: 1.06, 2.05; p = 0.023), and (OR = 1.47, CI: 1.01, 2.18; p = 0.047), respectively. The BMKR and quantile-based g-computation models revealed consistent associations for single exposures and there was insufficient evidence for the associations of the mixed exposure of bisphenols with precocious puberty. In conclusion, BPA substitutes such as BPS, TBBPA, and BPFL may be associated with an increased risk of precocious puberty in girls.

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.

Exposure to Bisphenol A and Its Analogs among Thai School-Age Children

Bisphenol F (BPF) and bisphenol S (BPS) have become popular substitutes for bisphenol A (BPA) in the plastic industry due to concerns over BPA's adverse effects. However, there is limited information on children's exposure to these chemicals. This study aims to assess the extent of BPA, BPF, and BPS exposure and determine factors that influence such exposure. A group of Thai children (age 6-13 years, N = 358) were recruited between October 2019 and 2020. Two first-morning voids were collected one week apart. Demographic and exposure-related information was gathered. Urinary concentrations of bisphenols were analyzed by liquid chromatography and tandem mass spectrometry. Correlation between bisphenol concentrations with age, body weight, and sources of bisphenol exposure, was determined using generalized estimating equations with linear model. BPA, BPF, and BPS were detected at 79.6%, 31.0%, and 16.8%, with geometric mean (GM) concentrations of 1.41, 0.013, and 0.014 ng/mL, respectively. Younger children aged <10 years exhibited 1.3-1.6 times higher GM levels of all bisphenols compared to older children. Exposure to food stored in plastic containers was associated with higher levels of BPF and BPS. In conclusion, BPA was the most frequently detected bisphenol in urine samples from Thai children, followed by BPF and BPS.

Association between Serum Per- and Polyfluoroalkyl Substance Levels and Risk of Central and Peripheral Precocious Puberty in Girls

Concerns about the endocrine-disrupting effects of per- and polyfluoroalkyl substances (PFASs) have raised questions about their potential influence on precocious puberty in girls, which is an emerging concern in some populations. However, epidemiological evidence is lacking. In this study, 882 serum samples were collected from girls with central precocious puberty (CPP, n = 226), peripheral precocious puberty (PPP, n = 316), and healthy controls (n = 340) in 2021 in Shanghai, China. The serum levels of 25 legacy and emerging PFASs and 17 steroids were measured. Results showed that PFAS exposure was positively associated with estradiol levels. Eleven PFASs were significantly or marginally associated with the higher odds of the overall precocious puberty. Across subtypes, PFASs were more clearly associated with PPP, while the associations with CPP were consistent in direction but did not reach statistical significance. These findings were consistent with the assessment of PFAS mixtures using quantile-based g-computation (qgcomp) and Bayesian kernel machine regression, with perfluorobutane sulfonate and 6:2 polyfluorinated ether sulfonate showing the highest contribution to joint effects. Although changes in serum estradiol could arise from various factors, our results suggest that the PFAS exposure may contribute to the increase in estradiol secretion, thereby increasing the risk of precocious puberty, especially PPP. The potential effects of PFASs on precocious puberty warrant further investigation, given the associated complications of public health concern, including psychological distress and increased risk of multiple diseases.

Gut microbiome combined with metabolomics reveals biomarkers and pathways in central precocious puberty

BACKGROUND

Central precocious puberty (CPP) is a common disease in prepubertal children and results mainly from disorders in the endocrine system. Emerging evidence has highlighted the involvement of gut microbes in hormone secretion, but their roles and downstream metabolic pathways in CPP remain unknown.

METHODS

To explore the gut microbes and metabolism alterations in CPP, we performed the 16S rRNA sequencing and untargeted metabolomics profiling for 91 CPP patients and 59 healthy controls. Bioinformatics and statistical analyses, including the comparisons of alpha and beta diversity, abundances of microbes, were undertaken on the 16S rRNA gene sequences and metabolism profiling. Classifiers were constructed based on the microorganisms and metabolites. Functional and pathway enrichment analyses were performed for identification of the altered microorganisms and metabolites in CPP.

RESULTS

We integrated a multi-omics approach to investigate the alterations and functional characteristics of gut microbes and metabolites in CPP patients. The fecal microbiome profiles and fecal and blood metabolite profiles for 91 CPP patients and 59 healthy controls were generated and compared. We identified the altered microorganisms and metabolites during the development of CPP and constructed a machine learning-based classifier for distinguishing CPP. The Area Under Curves (AUCs) of the classifies were ranged from 0.832 to 1.00. In addition, functional analysis of the gut microbiota revealed that the nitric oxide synthesis was closely associated with the progression of CPP. Finally, we investigated the metabolic potential of gut microbes and discovered the genus Streptococcus could be a candidate molecular marker for CPP treatment.

CONCLUSIONS

Overall, we utilized multi-omics data from microorganisms and metabolites to build a classifier for discriminating CPP patients from the common populations and recognized potential therapeutic molecular markers for CPP through comprehensive analyses.

Evaluation of toxicological effects of bisphenol S with an in vitro human bone marrow mesenchymal stem cell: Implications for bone health

As the use of bisphenol A (BPA) has been restricted in consumer products, bisphenol S (BPS) is one major alternative to BPA for various materials, leading to growing concerns about its health risks in human beings. However, little is known about the toxic effects of BPS on bone health. We employed human bone marrow mesenchymal stem cells (hBMSCs) for the in vitro assessment of BPS on cell proliferation, differentiation, and self-renewal. Our study revealed that BPS at concentrations of 10^-10-10^-7 M increased cell viability but induced the morphological changes of hBMSCs. Moreover, BPS decreased ROS generation and increased Nrf2 expression. Furthermore, BPS not only activated ERα/β expression but also increased β-catenin expression and induced the replicative senescence of hBMSCs. Furthermore, we found that the upregulation of β-catenin induced by BPS was mediated, in part, by ER signaling. Overall, our results suggested BPS exposure caused the homeostatic imbalance of hBMSCs.

Impact of Bisphenol A on Structure and Function of Mitochondria: A Critical Review

Bisphenol A (BPA) is an industrial chemical used extensively to manufacture polycarbonate plastics and epoxy resins. Because of its estrogen-mimicking properties, BPA acts as an endocrine-disrupting chemical. It has gained attention due to its high chances of daily and constant human exposure, bioaccumulation, and the ability to cause cellular toxicities and diseases at extremely low doses. Several elegant studies have shown that BPA can exert cellular toxicities by interfering with the structure and function of mitochondria, leading to mitochondrial dysfunction. Exposure to BPA results in oxidative stress and alterations in mitochondrial DNA (mtDNA), mitochondrial biogenesis, bioenergetics, mitochondrial membrane potential (MMP) decline, mitophagy, and apoptosis. Accumulation of reactive oxygen species (ROS) in conjunction with oxidative damage may be responsible for causing BPA-mediated cellular toxicity. Thus, several reports have suggested using antioxidant treatment to mitigate the toxicological effects of BPA. The present literature review emphasizes the adverse effects of BPA on mitochondria, with a comprehensive note on the molecular aspects of the structural and functional alterations in mitochondria in response to BPA exposure. The review also confers the possible approaches to alleviate BPA-mediated oxidative damage and the existing knowledge gaps in this emerging area of research.

Deciphering the Roles & Regulation of Estradiol Signaling during Female Mini-Puberty: Insights from Mouse Models

Mini-puberty of infancy is a short developmental phase occurring in humans and other mammals after birth. In females, it corresponds to transient and robust activation of the hypothalamo-pituitary-ovarian (HPO) axis revealed by high levels of gonadotropin hormones, follicular growth, and increased estradiol production by the ovary. The roles of estradiol signaling during this intriguing developmental phase are not yet well known, but accumulating data support the idea that it aids in the implementation of reproductive function. This review aims to provide in-depth information on HPO activity during this particular developmental phase in several mammal species, including humans, and to propose emerging hypotheses on the putative effect of estradiol signaling on the development and function of organs involved in female reproduction.

Exposure to antibiotics and precocious puberty in children: A school-based cross-sectional study in China

Foods and water can be contaminated with antibiotics in China, which may affect children's health, but evidence on antibiotic exposure with precocious puberty (PP) is limited. This study explored the association of antibiotic exposure with PP in a school-based setting. A cross-sectional study with multistage stratified cluster random sampling was conducted in Zhongshan City, Guangdong Province and Qufu City, Shandong Province in China from October 11 to December 5, 2019. A first-morning urine sample was collected to detect antibiotic exposure. We detected 33 of 45 types of antibiotics from eight categories in 928 primary school children aged 6-12 years using HPLS-MS/MS. Detection rate of antibiotics was stratified by sex, study site, and BMI. The Tanner stages were assessed by professional pediatricians from local hospitals. PP is defined as the onset of secondary characters before 8-year-old or menarche before 10-year-old for girls and before 9-year-old for boys. Multivariable logistic regression was performed to examine the association between antibiotic exposure and PP after adjusting potential confounders. The overall detection rate of antibiotics was 93.0% in 928 children. We found the detection rate of tetracyclines and fluoroquinolones in children with PP was significantly higher than that of children with normal puberty (41.4% vs 29.9%, 56.8% vs 50.6%, respectively, all p < 0.05). Both fluoroquinolones (odds ratio (OR): 1.835, 95% confidence interval (CI): 1.066-3.158) and tetracyclines (OR: 2.120, 95% CI: 1.175-3.825) were associated with increased OR of PP after adjusting sex, age, BMI, study site, and family income. Specifically, compared to the values less than the limits of detection, low concentration of ofloxacin from fluoroquinolones (OR: 2.056, 95% CI: 1.091-3.875) and high concentration of chlortetracycline (OR: 3.027, 95% CI: 1.126-8.140) and tetracycline from tetracyclines (OR: 2.756, 95% CI: 1.167-6.506) were associated with increased OR of PP. Exposure to antibiotics, especially fluoroquinolones and tetracyclines was positively associated with precocious puberty.

Perceptions and Treatment of Precocious Puberty: A Questionnaire Survey among Caregivers in South Korea

This study aims to provide the basis for developing complementary and alternative treatment approaches for precocious puberty (PP) by examining caregivers' awareness, along with their preferences and expectations from various treatments. It included data collected between July 2019 and March 2020, from 175 caregivers of children who were undergoing or had undergone treatment for PP. The questionnaire comprised 53 questions on the awareness, acquisition of information, perceptions of treatments, and concerns about PP, as well as awareness of habit management (HM) and children's actual habits. The collected data were analysed using the Chi-square test, t-tests, and one-way analysis of variance. The caregivers responded that PP could be recognized on the basis of breast development (79.8%) in girls and hair and body odor (73.1%) in boys. However, 86.9% of respondents were getting inaccurate information from the Internet. With respect to PP treatment approaches, 16% of respondents hoped to manage PP through conventional treatment (CT), 21.1% preferred traditional Korean medicine (TKM), and 62.3% preferred HM. Expectations of the effectiveness were highest in HM, followed by CT and TKM. Only the TKM group had statistically significant higher expectations than the nontreatment experience group (F = 4.566, p=0.004). The caregivers were concerned about the side effects and high costs of CT. Around 43% of respondents had difficulties with the management of their children's diet, 64.6% with exercise, and 57.1% with smart device usage. Clinicians should be aware of caregivers' information acquisition patterns, preferences and expectations of various treatments, and their concerns. Considering these results, clinicians should try to establish more appropriate treatment plans for children with PP.

Analysis of the Incidence and Risk Factors of Precocious Puberty in Girls during the COVID-19 Pandemic

Home quarantine due to the global coronavirus disease 2019 (COVID-19) pandemic has had a significant impact on children. Lifestyle changes have led to an increase in precocious puberty (PP) among girls, and the underlying risk factors for this remain unclear. Thus, we aimed to assess the influence of environmental, genetic, nutritional, and other lifestyle factors on the risk of PP in girls. We evaluated the incidence of new-onset PP in girls during home quarantine for COVID-19 and analyzed the potential risk factors. This was a retrospective questionnaire and medical record-based study involving 22 representative medical units from 13 cities in Henan Province, China. Girls with new-onset PP (central precocious puberty, 58; premature thelarche, 58; age, 5-9 years) between February 2020 and May 2020 were included, along with 124 healthy, age-matched controls. The number of new-onset PP cases reported during the study period was compared with that reported between February and May in 2018 and 2019. Patients' families completed a questionnaire to assess potential risk factors. There was a 5.01- and 3.14-fold increase in the number of new-onset PP cases from 2018 to 2020 and from 2019 to 2020, respectively; the differences were statistically significant (p < 0.01). High-risk factors for PP included longer time spent using electronic devices, decreased exercise time, higher body mass index, vitamin D deficiency, young age (<12 years) of mother during menarche, consumption of fried food and processed meat, residence in rural areas, and consumption of off-season fruits. Thus, we found that lifestyle changes caused due to the COVID-19 pandemic led to a significant increase in PP in girls. Management of the risk factors identified in this study may help in PP prevention.

Difference of Precocious Puberty Between Before and During the COVID-19 Pandemic: A Cross-Sectional Study Among Shanghai School-Aged Girls

OBJECTIVE

To compared the incidence rates and clinical features of precocious girls before and during the COVID-19 pandemic among Shanghai school-aged girls, and explored the potential mechanisms.

METHODS

This cross-sectional study collected medical data about precocious girls between 2016 and 2020 from Shanghai Children's Medical Center. Data of inpatient precocious girls from March to August in 2016-2019 (n=246) and 2020 (n=237) were collected. Subjects with abnormal brain and pituitary gland MRI reports, other endocrine diseases or chronic diseases were excluded. Finally, 209 precocious girls were included in the 2016-2019 group and 191 precocious girls were include in the 2020 group. Monthly incidence rates and clinical features were compared between before and during the COVID-19 pandemic. Linear regression models were used to examine the associations between biomarkers to explore the potential mechanisms.

RESULTS

Monthly incidence rates of precocious puberty in outpatient girls from March to December 2020 (0.44-1.36%) and in inpatient girls from March to August 2020 (27.04-47.83%) were higher than those in 2016-2019 (0.30-0.52% and 10.53-18.42%, respectively). Serum concentrations of GnRH were higher in the 2020 group than in the 2016-2019 group (2.81 vs 1.99 mg/L). Serum concentrations of MKRN3 (1.02 vs 1.93 ng/ml) and ghrelin (0.38 vs 0.88 ng/ml) were lower in the 2020 group than in the 2016-2019 group. Moreover, the serum concentration of ghrelin was positively associated with the serum concentration of MKRN3 [β=0.891 (95% CI, 0.612, 1.171); p<0.001].

CONCLUSIONS

These findings suggest an increased incidence of precocious puberty during the COVID-19 pandemic among Shanghai school-aged girls, which may be associated with decreased serum concentrations of MKRN3 and ghrelin, and indicated ghrelin as a potential regulatory mechanism of puberty.

Biological clock and heredity in pubertal timing: what is new?

Puberty represents a milestone during a person's life and is characterized by several physical and psychological changes which end with the achievement of sexual maturation and of fertility. Puberty onset depends on a series of sophisticated, not completely understood, mechanisms certainly involving Gonadotropin-Releasing Hormone (GnRH) and its effects on pituitary gonadotropins. As recent evidence has demonstrated that pubertal timing deeply affects future adult health life, much efforts have been performed in order to clarify the exact actors involved in the onset and progression of puberty. Genetic factors are undoubtedly essential players in the regulation of pubertal development, accounting for approximately 50-80% of its variability. Mutations in genes such as KISS1, MKRN3 and DLK1 have been associated with central precocious puberty. Interestingly, a possible involvement of epigenetic mechanisms has been proposed as additional element able to affect pubertal phase. Environmental factors have recently attracted much attention. Indeed, an overall decrease in the age of puberty has been observed in the last decades. As genetic factors require long time to exert their effect, other players, such as environmental ones, may be involved. Special focus has been posed on nutritional status, endocrine-disrupting chemicals with non-conclusive results. Pubertal timing deeply affects future life, suggesting the need to clarify mechanisms driving pubertal onset and progression, in order to identify tailored therapeutic strategies and targets.

Prevalence of precocious puberty among Chinese children: a school population-based study

PURPOSE

To investigate the prevalence of precocious puberty in school-based population in Zhongshan, Guangdong, China.

METHODS

We recruited a total of 4058 students in grades 1-3 using a multistage stratified cluster random sampling method in a population-based cross-sectional study. We evaluated height, weight, and development of breast and pubic hair in girls, breast development was evaluated by inspection and palpation combined with ultrasound detection for overweight and obese girls, and testicular volume and development of pubic hair in boys. We estimated overall, sex-, age, and district-specific prevalence of precocious puberty and examined the association between prevalence of precocious puberty and body mass index (BMI).

RESULTS

The unadjusted and adjusted prevalence of precocious puberty by Tanner stage was 4.74% (girls:8.78%, boys:2.58%) and 6.19% (girls:11.47%, boys:3.26%), respectively. In both urban and suburban areas, the prevalence of precocious puberty was higher in the overweight and obese group than in the normal-weight group (p < 0.05). The prevalence of precocious puberty among overweight (27.94%) and obese (48.00%) girls was higher than that of normal-weight girls (8.73%) (p value for trend < 0.05). In boys, the prevalence of precocious puberty in the obese (6.78%) group was higher than that in the normal-weight (2.86%) group (p < 0.05).

CONCLUSIONS

The prevalence of precocious puberty was high in China. Overweight and obesity was related to precocious puberty, but this correlation had gender differences and may be affected by other environmental factors.

Multisystemic alterations in humans induced by bisphenol A and phthalates: Experimental, epidemiological and clinical studies reveal the need to change health policies

A vast amount of evidence indicates that bisphenol A (BPA) and phthalates are widely distributed in the environment since these compounds are mass-produced for the manufacture of plastics and plasticizers. These compounds belong to a large group of substances termed endocrine-disrupting chemicals (EDC). It is well known that humans and living organisms are unavoidably and unintentionally exposed to BPA and phthalates from food packaging materials and many other everyday products. BPA and phthalates exert their effect by interfering with hormone synthesis, bioavailability, and action, thereby altering cellular proliferation and differentiation, tissue development, and the regulation of several physiological processes. In fact, these EDC can alter fetal programming at an epigenetic level, which can be transgenerational transmitted and may be involved in the development of various chronic pathologies later in the adulthood, including metabolic, reproductive and degenerative diseases, and certain types of cancer. In this review, we describe the most recent proposed mechanisms of action of these EDC and offer a compelling selection of experimental, epidemiological and clinical studies, which show evidence of how exposure to these pollutants affects our health during development, and their association with a wide range of reproductive, metabolic and neurological diseases, as well as hormone-related cancers. We stress the importance of concern in the general population and the urgent need for the medical health care system to closely monitor EDC levels in the population due to unavoidable and involuntary exposure to these pollutants and their impact on human health.

Effects of Environment and Lifestyle Factors on Premature Ovarian Failure

Premature ovarian insufficiency (POI) or primary ovarian failure is defined as a cessation of the menstrual cycle in women younger than 40 years old. It is strictly defined as more than 4 months of oligomenorrhea or amenorrhea in a woman <40 years old, associated with at least two follicle-stimulating hormone (FSH) levels >25 U/L in the menopausal range, detected more than 4 weeks apart. It is estimated that POI was affected 1 and 2% of women. Although 80% of POI cases are of unknown etiology, it is suggested that genetic disorder, autoimmune origin, toxins, and environmental factors, as well as personal lifestyles, may be risk factors of developing POI. In this section, we will discuss the influences of environmental and lifestyle factors on POI. Moreover updated basic research findings regarding how these environmental factors affect female ovarian function via epigenetic regulations will also be discussed.

Association between phenols exposure and earlier puberty in children: A systematic review and meta-analysis

OBJECTIVE

To identify the association between phenolic chemicals and the risk of earlier puberty based on the available evidence by systematic review and meta-analysis.

METHODS

Databases PubMed, Web of Science, and Cochrane Library were searched and retrieved appropriate journal articles on the association between phenols exposure and earlier puberty in children published before February 14, 2020. Stata software version 12.0 and Excel were used for statistical analysis.

RESULTS

Nine studies were included in the meta-analysis with total subjects of 4737. All the subjects included in our studies were girls. The pooled estimate has shown the association between 2, 5- dichrolophenol exposure, and earlier puberty in children with effect size (ES) 1.13 (95% CI: 1.06, 1.20). Exposed to other types of phenolic chemicals such as bisphenol A, Triclosan, Benzophenone-3 were not statistically significant associated with the risk of earlier puberty in children with the overall pooled estimates of ES of 1.09 (95%CI: 0.88, 1.35), ES 1.05(95% CI: 0.96, 1.15), and ES 0.98 (95% CI: 0.88, 1.10) respectively.

CONCLUSION

Our results portray that phenols particularly 2, 5- dichlorophenol exposure might be associated with the risk of earlier puberty in children. Also, caution should be taken to other type of phenolic chemicals since in subgroup analysis some individual studies have shown a positive relationship between bisphenol A, Triclosan and Benzophenone-3 exposures, and the risk of earlier puberty in children. Future cohort studies should be conducted with more sample sizes to determine the relationship between 2, 5- dichlorophenol, and the risk of earlier puberty in children of all gender.

Endocrine-Disrupting Chemicals and Their Effects during Female Puberty: A Review of Current Evidence

Puberty is the process of physical changes between childhood and adulthood during which adolescents reach sexual maturity and become capable of reproduction. It is considered one of the main temporal windows of susceptibility for the influence of the endocrine-disrupting chemicals (EDCs). EDCs may act as single chemical agents or as chemical mixtures; they can be pubertal influencers, accelerating and anticipating the processing of maturation of secondary sexual characteristics. Moreover, recent studies have started to point out how exposure to EDCs during puberty may predispose to breast cancer later in life. In fact, the estrogen-mimicking endocrine disruptors (EEDs) may influence breast tissue development during puberty in two main ways: the first is the action on the proliferation of the breast stromal cells, the second concerns epigenetic mechanisms. The aim of this mini-review was to better highlight what is new and what is not completely known regarding the role of EDCs during puberty.

Determination of bisphenol A in barreled drinking water by a SPE-LC-MS method

A quantitative method was established to determine the well-known endocrine disruptor bisphenol A (BPA) in barreled drinking water. Samples were pretreated by solid phase extraction (SPE), and then analyzed by liquid chromatography-mass spectrometry (LC-MS). Working standard solutions were obtained by pretreatment of a series of aqueous standard solutions over the concentration range of 122.9-1190.7 ng L^-1. The linear calibration curve was Y = 69.4X + 2206.2 with the correlation coefficient (R²) of 0.9929. The average recoveries from spiked samples were more than 91.6%. The relative standard deviations (n = 6) were less than 9.6%. The method allowed the detection of 7.0 ng L^-1 BPA in barreled drinking water. Typical barreled drinking water products in the market were detected. As results, thirty-five of fifty-two commercial samples were found to contain BPA with a maximum concentration of 898.7 ng L^-1. The occurrence of BPA in barreled drinking water may be due to the pollution of raw water, the inefficiency of purification processes and the migration of BPA from barrels. The daily exposure of adults to BPA through drinking barreled drinking water is far below the current human tolerable daily intake (TDI) set by European Food Safety Authority (EFSA).

Minipuberty: Looking Back to Understand Moving Forward

Hypothalamic-pituitary-gonadal (HPG) axis activation occurs three times in life: the first is during fetal life, and has a crucial role in sex determination, the second time is during the first postnatal months of life, and the third is with the onset of puberty. These windows of activation recall the three windows of the "Developmental Origin of Health and Disease" (DOHaD) paradigm and may play a substantial role in several aspects of human development, such as growth, behavior, and neurodevelopment. From the second trimester of pregnancy there is a peak in gonadotropin levels, followed by a decrease toward term and complete suppression at birth. This is due to the negative feedback of placental estrogens. Studies have shown that in this prenatal HPG axis activation, gonadotropin levels display a sex-related pattern which plays a crucial role in sex differentiation of internal and external genitalia. Soon after birth, there is a new increase in LH, FSH, and sex hormone concentrations, both in males and females, due to HPG re-activation. This postnatal activation is known as "minipuberty." The HPG axis activity in infancy demonstrates a pulsatile pattern with hormone levels similar to those of true puberty. We review the studies on the changes of these hormones in infancy and their influence on several aspects of future development, from linear growth to fertility and neurobehavior.

The analysis of endocrine disruptors in patients with central precocious puberty

Background

A few studies have reported a positive association between phthalate exposure and pubertal timing, but several conflicting reports exist. The main objective of the study was to determine whether phthalate exposure was associated with central precocious puberty in girls.

Methods

This was a multicenter case-control study wherein 47 girls with central precocious puberty (CPP) and 47 controls (26 pre-pubertal girls and 21 pubertal girls) were enrolled. No obese girls were included. Five phthalate metabolites (creatinine adjusted) and bisphenol A (BPA) were measured in the first spot urine samples of these 94 girls in the early morning.

Results

The median values of monobenzyl phthalate (MBzP), mono-2-ethyl-5-carboxypentyl phthalate (MECPP), mono-2-ethyl-5-hydroxyhexyl phthalate (MEHHP), mono-2-ethyl-5-oxohexyl phthalate (MEOHP), and mono-n-butyl phthalate (MnBP) were 3.1, 29.3, 18.0, 15.4, and 25.2 μg/g creatinine in the CPP group, 4.3, 53.7, 35.7, 29.1, and 66.0 μg/g creatinine in the pre-pubertal control group, and 1.7, 28.7, 21.4, 12.1, and 33.3 μg/g creatinine in the pubertal control group, respectively.

The urinary concentration of the five phthalates was significantly lower in the CPP group than in the pre-pubertal control group (P < 0.001). Conversely, there was no significant difference in the urinary concentration of the five phthalates between the CPP and pubertal control groups (P values: 0.077 for MBzP, 0.733 for MECPP, 0.762 for MEHHP, 0.405 for MEOHP, and 0.981 for MnBP). In addition, the BPA level was not significantly different between the CPP and pubertal control groups (BPA median values: 0.63 μg/g creatinine, the CPP group; 1.7 μg/g creatinine, the pubertal control group; P value = 0.092).

Conclusions

Our study showed that there was no significant difference in the urinary phthalate levels between the CPP and pubertal control groups. Moreover, phthalate metabolites were significantly lower in the CPP group than in the pre-pubertal control group. Further investigation about endocrine disruptors and pubertal progression is needed.

Hazards of bisphenol A -- blocks RNA splicing leading to abnormal testicular development in offspring male mice

This study was conducted to investigate the effects of maternal exposure to BPA on testicular development in offspring males. Pregnant Kunming mice were randomly divided into 7 groups with 20 mice in each group. Group A was the control group and the mice were given distilled water orally. Mice in groups B, C, D, E, F, G received BPA orally at a dose of 0.05 mg/kg/d, 0.5 mg/kg/d, 5 mg/kg/d, 10 mg/kg/d, 20 mg/kg/d, 50 mg/kg/d, respectively. F0 mice were exposed to BPA for 40 days from gestation day 0 to lactation day 21. F1 male mice were sacrificed at weaning (postnatal day 21). Histological observations revealed architectural damages in testis in BPA exposed groups. The testicular organ index increased significantly when the BPA oral exposure dose was above 20 mg/kg/d (P < 0.05). BPA contents in serum of F1 male mice increased significantly when BPA was above 5 mg/kg/d (P < 0.05), while the contents significant increased in maternal serum when BPA was higher than 0.5 mg/kg/d. The damage of cell nuclear DNA of testis was significantly aggravated when BPA was above 5 mg/kg/d. The expression of AR in the testis was significantly increased when BPA was above 20 mg/kg/d (P < 0.05). Transcriptome sequencing showed that the Snrnp 40 which encoding U5 snRNA subunit was significantly up-regulated in spliceosome pathway, and the Hnrnpu which encoding splicing universal protein component was significantly down-regulated. The blockage of spliceosome might be one of the reasons why BPA affects testicular development.

The adverse health effects of bisphenol A and related toxicity mechanisms

Bisphenol A (BPA) is an industrial component commonly used in synthesis of polycarbonate plastics, epoxy resin and other polymer materials. Due to its mass productions and widespread applications, the presence of BPA is ubiquitous in the environment. BPA can enter the body via different ways such as digestive tract, respiratory tract and dermal tract. As an endocrine disruptor, BPA has estrogen-like and anti-androgen effects causing damages to different tissues and organs, including reproductive system, immune system and neuroendocrine system, etc. Recently, it has been shown that BPA could induce carcinogenesis and mutagenesis in animal models. Here, the underlying mechanisms of BPA-induced multi-organ toxicity were well summarized, involving the receptor pathways, disruption of neuroendocrine system, inhibition of enzymes, modulation of immune and inflammatory responses, as well as genotoxic and epigenetic mechanisms. The aim of this review is to compile the available current research data regarding BPA and provide an overview of the current status of BPA exposure and relevant health effects covering reproductive, developmental, metabolic, immuno, respiratory, hepatic and renal toxicity and carcinogenesis of BPA. This review provides comprehensive data of BPA toxicity on human health and related mechanisms. We also identify any missing data which should be addressed by further studies.

Early-life exposure to endocrine-disrupting chemicals and pubertal development in girls

Over the last decades, the onset of puberty in girls has occurred earlier, but the tempo of pubertal progression has been relatively slower, resulting in a younger age at puberty onset without a change in age at menarche. Sufficient energy availability and adiposity contribute to early pubertal development, and environmental factors, such as endocrine-disrupting chemicals (EDCs), may affect not only the control of energy balance, but also puberty and reproduction. EDCs are hormonally active substances that can perturb puberty by acting both peripherally on target organs, such as adipose tissue or adrenal glands, and/or centrally on the hypothalamic-pituitary-gonadal (HPG) axis. Depending on whether the exposure takes place earlier during fetal and neonatal life or later during early childhood, EDCs can lead to different outcomes through different mechanisms. Evidence of associations between exposures to EDCs and altered pubertal timing makes it reasonable to support their relationship. However, human epidemiologic data are limited or inconsistent and cannot provide sufficient evidence for a causal relationship between EDC exposure and changes in pubertal timing. Further investigation is warranted to determine the overall or different effects of EDCs exposure during prenatal or childhood windows on pubertal milestones and to reveal the underlying mechanisms, including epigenetic marks, whereby early-life exposure to EDCs affect the HPG-peripheral tissue axis.

Urinary levels, composition profile and cumulative risk of bisphenols in preschool-aged children from Nanjing suburb, China

Due to the extensive use in consumer products, the bisphenols (BPs) pollution in the environments has aggravated and people are frequently exposed to BPs. In this research, four BPs, i.e., bisphenol A (BPA), bisphenol F (BPF), bisphenol S (BPS) and bisphenol AF (BPAF), were determined in urine samples collected from Gaochun District preschool-age children and the concentrations, distribution profiles, potential sources and cumulative risk assessment of the target compounds were studied. Total concentrations of 4 BPs ranged from 2 to 3113.1 ng/L, with the average concentration of 648.6 ng/L. BPA was the predominant congener (accounting for 94%), followed by BPS. Correlation analysis indicated a negative relationship between BPA and BPAF (R = -0.273, p < 0.05). The estimated daily intakes suggested that young females were more sensitive to BPs. Moreover, the cumulative risk for hazard quotient (HQ) of BPA has been evaluated and the results showed that no high risk had occurred. It provided basic information on the occurrence and human exposure to urinary BPs of preschool aged children from Gaochun District.