Bisphenol A and pubertal height growth in school-aged children

Temporal and geographic variability of bisphenol levels in humans: A systematic review and meta-analysis of international biomonitoring data

INTRODUCTION

Bisphenols are endocrine-disrupting chemicals known to contribute to chronic disease across the lifespan. With increased awareness of their health effects, changes in regulation and health behaviors have contributed to reductions in urinary bisphenol A (BPA) levels in the United States, Canada, and Europe. However, global trends in bisphenols outside these regions, especially bisphenol S (BPS) exposure, have been less studied.

AIM

We examine trends in urinary BPA and BPS concentration in non-occupationally exposed populations, where representative data at a country level is unavailable.

METHODS

We systematically reviewed studies published between 2000 and 2023 that included urinary bisphenol concentrations. We examined BPA and BPS concentration changes by sampling year, controlling for region, age, and pregnancy status, with and without a quadratic term and geometric mean, via mixed-effects meta-regression models with a random intercept and sensitivity analysis. We identified heterogeneity using Cochran's Q-statistic, I2 index, and funnel plots.

RESULTS

The final analytic sample consisted of 164 studies. We observed positive non-linear associations between time and BPA concentration internationally (beta: 0.02 ng/mL/year2, 95% CI: [0.01, 0.03]) and in Eastern and Pacific Asia (beta: 0.03 ng/mL/year2, 95% CI: [0.02, 0.05]). We also observed non-linear associations of time with both BPA and BPS concentrations in the Middle East and South Asia (beta: 0.13 ng/mL/year2, 95% CI: [0.01, 0.25] and beta: 0.29 ng/mL/year2, 95% CI: [-0.50, -0.08], respectively). In the sensitivity analyses excluding studies with geometric or arithmetic mean values, each displayed significant shifts from the main findings with some consistent outcomes occurring internationally and/or in specific regions. Heterogeneity was high across studies, suggesting possible bias in our estimations.

CONCLUSIONS

Our findings provide evidence for concern about increasing population exposure to BPA and BPS. Further studies estimating attributable disease burden and costs at regional and global levels are warranted to show these chemicals' impact on population health and economies.

Polystyrene microplastic-induced endoplasmic reticulum stress contributes to growth plate endochondral ossification disorder in young rat

BACKGROUND

Previous studies on the effects of microplastics (MPs) on bone in early development are limited. This study aimed to investigate the adverse effects of MPs on bone in young rats and the potential mechanism.

METHODS

Three-week-old female rats were orally administered MPs for 28 days, and endoplasmic reticulum (ER) stress inhibitor salubrinal (SAL) and ER stress agonist tunicamycin (TM) were added to evaluate the effect of ER stress on toxicity of MPs. The indicators of growth and plasma markers of bone turnover were evaluated. Tibias were analyzed using micro-computed tomography (micro-CT). Histomorphological staining of growth plates was performed, and related gene expression of growth plate chondrocytes was tested.

RESULTS

After exposure of MPs, the rats had decreased growth, shortened tibial length, and altered blood calcium and phosphorus metabolism. Trabecular bone was sparse according to micro-CT inspection. In the growth plate, the thickness of proliferative zone substantial reduced while the thickness of hypertrophic zone increased significantly, and the chondrocytes were scarce and irregularly arranged according to tibial histological staining. The transcription of the ER stress-related genes BIP, PERK, ATF4, and CHOP dramatically increased, and the transcription factors involved in chondrocyte proliferation, differentiation, apoptosis, and matrix secretion were aberrant according to RT-qPCR and western blotting. Moreover, the addition of TM showed higher percentage of chondrocyte death. Administration of SAL alleviated all of the MPs-induced symptoms.

CONCLUSION

These results indicated that MPs could induce growth retardation and longitudinal bone damage in early development. The toxicity of MPs may attribute to induced ER stress and impaired essential processes of the endochondral ossification after MPs exposure.

A new identity of microcystins: Environmental endocrine disruptors? An evidence-based review

Microcystins (MCs) are widely distributed cyanobacterial toxins in eutrophic waters. At present, the endocrine-disrupting effects of MCs have been extensively studied, but whether MCs can be classified as environmental endocrine disruptors (EDCs) is still unclear. This review is aimed to evaluate the rationality for MCs as to be classified as EDCs based on the available evidence. It has been identified that MCs meet eight of ten key characteristics of chemicals that can be classified as EDCs. MCs interfere with the six processes, including synthesis, release, circulation, metabolism, binding and action of natural hormones in the body. Also, they are fit two other characteristics of EDC: altering the fate of producing/responding cells and epigenetic modification. Further evidence indicates that the endocrine-disrupting effect of MCs may be an important cause of adverse health outcomes such as metabolic disorders, reproductive disorders and effects on the growth and development of offspring. Generally, MCs have endocrine-disrupting properties, suggesting that it is reasonable for them to be considered EDCs. This is of great importance in understanding and evaluating the harm done by MCs on humans.

Potential occupational exposure of parents to endocrine disrupting chemicals, adverse birth outcomes, and the modification effects of multi-vitamins supplement and infant sex

BACKGROUND

Maternal occupational exposure to endocrine disrupting chemicals (EDCs) may have adverse effect on birth outcomes. However, little is known about paternal EDCs exposure and the combined effect of parental exposure on birth outcomes.

OBJECTIVES

To assess the effects of both maternal and paternal occupational EDCs exposure on adverse birth outcomes, and further explore if multi-vitamins supplement and infant sex modify the association.

METHODS

We conducted a prospective cohort study of 5421 mother-father-newborn groups in Guangzhou, China. A questionnaire informed by a job exposure matrix (JEM) was applied to collect parental occupational EDCs exposure based on the type of work performed. We used logistic regression to estimate association between parental EDCs exposure and birth outcomes (including preterm birth (PTB), low birth weight (LBW), birth defects and congenital heart defects (CHD)). Stratified analyses and Cochran Q tests were performed to assess the modifying effect of maternal multi-vitamins supplement use and infant sex.

RESULTS

Compared with mothers unexposed, we found that mothers those exposed to EDCs were associated with increased odds of birth defects (aOR=1.70, 95% confidence interval (CI): 1.10-2.62), especially for those exposed for > 1.5 years (aOR= 3.00, 95% CIs: 1.78-5.03), or those with directly occupational exposed to EDCs (aOR= 2.94, 95% CIs: 1.72-5.04). Maternal exposure for > 1.5 years and direct exposure increased the risk of CHD, with aORs of 2.47 (1.21-5.02) and 2.79 (1.37-5.69), respectively. Stronger adverse effects were also observed when mothers and fathers were both exposed to EDCs. Paternal occupational EDCs exposure and exposure ≤ 1.5 years was associated with increased odds of LBW, with aORs of 2.14 (1.63-2.79) and 1.54 (1.10-2.15), respectively. When stratified by multi-vitamins supplement and infant sex, we observed slightly stronger effects for maternal exposure on birth defects/CHD as well as paternal EDCs exposure on PTB and LBW, among those without multi-vitamins supplement and among male babies, although the modification effects were not significant.

CONCLUSION

Maternal exposure to EDCs was associated with greater odds of birth defects and CHD, while paternal exposure was mainly associated with greater odds of LBW. These effects tend to be stronger among mothers without multi-vitamins supplement and among male babies.

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.

The hazardous threat of Bisphenol A: Toxicity, detection and remediation

Bisphenol A (or BPA) is a toxic endocrine disrupting chemical that is released into the environment through modern manufacturing practices. BPA can disrupt the production, function and activity of endogenous hormones causing irregularity in the hypothalamus-pituitary-gonadal glands and also the pituitary-adrenal function. BPA has immuno-suppression activity and can downregulate T cells and antioxidant genes. The genotoxicity and cytotoxicity of BPA is paramount and therefore, there is an immediate need to properly detect and remediate its influence. In this review, we discuss the toxic effects of BPA on different metabolic systems in the human body, followed by its mechanism of action. Various novel detection techniques (LC-MS, GC-MS, capillary electrophoresis, immunoassay and sensors) involving a pretreatment step (liquid-liquid microextraction and molecularly imprinted solid-phase extraction) have also been detailed. Mechanisms of various remediation strategies, including biodegradation using native enzymes, membrane separation processes, photocatalytic oxidation, use of nanosorbents and thermal degradation has been detailed. An overview of the global regulations pertaining to BPA has been presented. More investigations are required on the efficiency of integrated remediation technologies rather than standalone methods for BPA removal. The effect of processing operations on BPA in food matrices is also warranted to restrict its transport into food products.

Urinary antibiotic level of school children in Shanghai, East China, 2017-2020

In recent years, an extensive exposure to antibiotics from various sources has been demonstrated in China by the biomonitoring method, but the temporal trend remains little known. The study aim was to explore the temporal trend of exposure to antibiotics and associated health risk in children. A dynamic child cohort was established in Shanghai, East China between 2017 and 2020. A total of 684 school children aged 7-11 years were included, and 280 in 2017, 279 in 2018, 288 in 2019, and 287 in 2020 participated in annual surveys. Twenty-three typical antibiotics and three metabolites from five categories (four tetracyclines, five qinolones, six macrolides, eight sulfonamides, and three phenicols), bisphenol A (BPA), and monobutyl phthalate (MBP) were determined in urine. Logistic regression analysis with generalized estimating equations was conducted to investigate the associations between various variables and the detection frequency of antibiotics in urine. Seventeen antibiotics and three metabolites were found in 51.9% of all urine samples. Compared to 2017, the detection frequency in urine reduced 31.8% in 2020 for all antibiotics (58.2% vs 39.7%) and reduced 36.8%-55.8% for tetracyclines (11.4% vs 7.0%), qinolones (34.3% vs 21.3%), macrolides (8.6% vs 3.8%), sulfonamides (16.4% vs 8.7%), and phenicols (19.3% vs 12.2%). After accounting for personal characteristics, food consumption, and urinary BPA and MBP, a decreasing temporal trend of detection frequencies was observed from 2017 to 2020 for most antibiotics. Urinary concentration, estimated daily intake, and acceptable daily intake-based health risk of antibiotics showed a temporal trend similar to detection frequency. There was an extensive exposure to antibiotics in children. However, a decreasing temporal trend occurred for the exposure during the period from 2017 to 2020. The trend was likely to be caused by decreased antibiotic use and/or decreased residues in food and/or drinking water.

Gestational and lactational exposure to BPA, but not BPS, negatively impacts trabecular microarchitecture and cortical geometry in adult male offspring

Bisphenol-A (BPA) and bisphenol-S (BPS) are endocrine disrupting chemicals (EDCs) found primarily in plastics. Estrogen is a primary hormonal regulator of skeletal growth and development; however, the impact of gestational BPA or BPS exposure on skeletal health of offspring remains relatively unknown. Here, adult female mice were randomized into three treatment groups: 200 μg BPA/kg BW (BPA), 200 μg BPS/kg BW (BPS) or control (CON). Animals were then further randomized to exercising (EX) or sedentary (SED) groups. Treatment continued through mating, gestation, and lactation. One male offspring from each dam (n = 6-8/group) was assessed at 16 weeks of age to evaluate effects of EDC exposure on the adult skeleton. Cortical geometry of the mid-diaphysis and trabecular microarchitecture of the distal femur were assessed via micro-CT. Biomechanical strength and mineral apposition rate of the femoral diaphysis were assessed via three-point bending and dynamic histomorphometry, respectively. Two-factor ANOVA or ANCOVA were used to determine the effects of maternal EX and BPA or BPS on trabecular and cortical bone outcomes. Maternal EX led to a significant decrease in body fat percentage and bone stiffness, independent of EDC exposure. Offspring exposed to BPA had significantly lower trabecular bone volume, trabecular number, connectivity density, cortical thickness, and greater trabecular spacing compared to BPS or CON animals. In conclusion, gestational BPA, but not BPS, exposure negatively impacted trabecular microarchitecture and cortical geometry in adult male offspring. If these findings translate to humans, this could have significant public health impacts on expecting women or those seeking to become pregnant.

Gestational and lactational exposure to BPA or BPS has minimal effects on skeletal outcomes in adult female mice

Bisphenol-A (BPA) and bisphenol-S (BPS) are estrogen disrupting chemicals (EDCs) found in the environment and common household items. Estrogen is a primary hormonal regulator of bone growth and development; however, the impact of gestational BPA or BPS exposure on skeletal health of offspring remains relatively unknown. In this longitudinal study, adult female mice were randomized into three groups: 200 μg BPA/kg BW (BPA), 200 μg BPS/kg BW (BPS) or control (CON). Animals in each group were further randomized to exercise treatment (EX) or sedentary (SED) control, resulting in six overall groups. BPA/BPS/CON and EX/SED treatment were initiated prior to mating and continued through mating, gestation, and lactation. One female offspring from each dam (n = 6/group) was assessed at 17 weeks of age to evaluate effects of EDC exposure on the adult skeleton. Cortical geometry of the mid-diaphysis and trabecular microarchitecture of the distal femur were assessed via micro-computed tomography. Biomechanical strength and mineral apposition rate of the femoral diaphysis were assessed via three-point bending and dynamic histomorphometry, respectively. Sclerostin expression was measured using immunohistochemistry. Two-factor ANOVA or ANCOVA were used to determine the effects of maternal exercise and BPA or BPS exposure on trabecular and cortical bone outcomes, respectively. Consistent with prior studies, there were no significant differences in body weight, femoral length, cortical geometry, trabecular microarchitecture, or biomechanical strength between groups in female offspring. In conclusion, gestational BPA exposure and maternal exercise have minimal impact on skeletal outcomes in female adult offspring.

Bisphenol A and Its Analogues Deteriorate the Hormones Physiological Function of the Male Reproductive System: A Mini-Review

BPA is identified as an endocrine-disrupting chemical that deteriorates the physiological function of the hormones of the male reproductive system. Bisphenol F (BPF), bisphenol S (BPS), and bisphenol AF (BPAF) are actively explored as substitutes for BPA and are known as BPA analogues in most manufacturing industries. These analogues may demonstrate the same adverse effects as BPA on the male reproductive system; however, toxicological data explaining the male reproductive hormones' physiological functions are still limited. Hence, this mini-review discusses the effects of BPA and its analogues on the physiological functions of hormones in the male reproductive system, focusing on the hypothalamus-pituitary-gonad (HPG) axis, steroidogenesis, and spermatogenesis outcomes. The BPA analogues mainly show a similar negative effect on the hormones' physiological functions, proven by alterations in the HPG axis and steroidogenesis via activation of the aromatase activity and reduction of spermatogenesis outcomes when compared to BPA in in vitro and in vivo studies. Human biomonitoring studies also provide significant adverse effects on the physiological functions of hormones in the male reproductive system. In conclusion, BPA and its analogues deteriorate the physiological functions of hormones in the male reproductive system as per in vitro, in vivo, and human biomonitoring studies.

Peripubertal Bisphenol A Exposure Imparts Detrimental Age-Related Changes in Body Composition, Cognition, and Hydrogen Sulfide Production Capacities

Aims: Peripubertal endocrine disruption has immediate and lifelong consequences on health, cognition, and lifespan. Disruption comes from dietary, environmental, and pharmaceutical sources. The plasticizer Bisphenol A (BPA) is one such endocrine disrupting chemical. However, it is unclear whether peripubertal BPA exposure incites long-lasting physiological, neuro-cognitive, and/or longevity-related metabolic impairments. Catabolism of cysteine via transsulfuration enzymes produces hydrogen sulfide (H2S), a redox-modulating gasotransmitter causative to endocrine and metabolic homeostasis and improved cognitive function with age. As thyroid hormone (TH) regulates hepatic H2S production and BPA is a TH receptor antagonist, we hypothesized that BPA exposure during peripubertal development impairs metabolic and neuro-cognitive/behavioral endpoints in aged mice, in part, due to altered peripheral and/or localized H2S production and redox status. Results: To test this, male C57BL/6J mice at 5 weeks of age were orally exposed daily for 5 weeks to 250 μg BPA/kg, defined as low dose group (LD BPA), or 250 mg BPA/kg, defined as high dose group (HD BPA). Both LD and HD BPA exposure decreased lean mass and increased fat mass accompanied by decreased serum total TH at advanced ages. In addition, LD BPA had an anxiogenic effect whereas HD BPA caused cognitive deficits. Notably, HD BPA disrupted tissue-specific H2S production capacities and/or protein persulfidation, with the former negatively correlated with memory deficits and oxidative stress. Innovation and Conclusion: These findings provide a potential mechanism of action for acute and long-term health impacts of BPA-induced peripubertal endocrine disruption and bolster the need for improved monitoring and limitation of adolescent BPA exposure.

Bisphenol A and its effects on the systemic organs of children

For the past two decades, growing research has been pointing to multiple repercussions of bisphenol A (BPA) exposure to human health. BPA is a synthetic oestrogen which primarily targets the endocrine system; however, the compound also disturbs other systemic organ functions, in which the magnitude of impacts in those other systems is as comparable to those in the endocrine system. To date, the discoveries on the association between BPA and health outcomes mainly came from animal and in vitro studies, with limited human studies which emphasised on children's health. In this comprehensive review, we summarised studies on human, in vivo and in vitro models to understand the consequences of pre-, post- and perinatal BPA exposure on the perinatal, children and adult health, encompassing cardiovascular, neurodevelopmental, endocrine and reproductive effects.Conclusion: Evidence from in vitro and animal studies may provide further support and better understanding on the correlation between environmental BPA exposure and its detrimental effects in humans and child development, despite the difficulties to draw direct causal relations of BPA effects on the pathophysiology of the diseases/syndromes in children, due to differences in body system complexity between children and adults, as well as between animal and in vitro models and humans. What is known: • Very limited reviews are available on how BPA adversely affects children's health. • Previous papers mainly covered two systems in children. What is new: • Comprehensive review on the detrimental effects of BPA on children health outcomes, including expectations on adult health outcomes following perinatal BPA exposure, as well as covering a small part of BPA alternatives. • Essentially, BPA exposure during pregnancy has huge impacts on the foetus in which it may cause changes in foetal epigenetic programming, resulting in disease onsets during childhood as well as adulthood.

Association of fish consumption with risk of all-cause and cardiovascular disease mortality: an 11-year follow-up of the Guangzhou Biobank Cohort Study

BACKGROUND

Whether fish consumption is associated with all-cause, cardiovascular (CVD), ischemic heart disease (IHD) and stroke mortality remains inconclusive. We examined the association of fish consumption with all-cause, cardiovascular (CVD), ischemic heart disease (IHD) and stroke mortality in older men and women in south China.

METHODS

A total of 18,215 participants including men and women without CVD at baseline (2003-2006) from Guangzhou Biobank Cohort Study (GBCS) were included and followed up till December 2017. Deaths were identified through record linkage with the Death Registry. Information on fish consumption was obtained using a food frequency questionnaire.

RESULTS

During an average follow-up of 11.4 (standard deviation = 2.1) years, 2,697 deaths occurred, including 917 total CVD, 397 IHD and 374 stroke deaths. After adjusting for potential confounders, compared with fish consumption of 0-3 servings/week (i.e., 0-21 g/day, one serving = 50 g), consumption of 4-6 servings/week (29-43 g/day) showed significantly lower risks of all-cause and CVD mortality (hazards ratio (HR) and 95% confidence interval (CI): 0.85 (0.76, 0.95) and 0.77 (0.64, 0.93), respectively), but the reduced risk of IHD mortality (HR (95% CI): 0.80 (0.60, 1.07)) was not significant. Consumption of 7-10 servings/week or higher showed no association with all-cause, CVD, IHD, and stroke mortality.

CONCLUSIONS

Moderate fish consumption of 4-6 servings/week (29-43 g/day) was associated with lower all-cause and CVD mortality risk. Our findings support the current general advice on regular fish consumption also in middle-aged and older adults.

Urinary bisphenol A levels in prepubertal children with exogenous obesity according to presence of metabolic syndrome

OBJECTIVES

Recent studies have shown a potential link between chronic exposure to Bisphenol A (BPA) and exogenous obesity, the prevalence of which has been increasing dramatically in all age groups and particularly among children in the last decades. In this study, we aimed at comparing BPA exposure levels between controls and otherwise healthy, drug-naive, pre-pubertal children having exogenous obesity with/without metabolic syndrome.

METHODS

A total of 63 pre-pubertal children with exogenous obesity whom 27 of them having metabolic syndrome attending Hacettepe University Ihsan Dogramaci Children's Hospital were included in this study. The control group consisted of 34 age- and sex-matched healthy children with no significant underlying medical conditions. Urinary BPA levels were measured using LC-MS/MS (high-performance liquid chromatography coupled with tandem mass spectrometry) methodology.

RESULTS

Urinary BPA levels among obese children were significantly higher than those of the control group (median: 22.9 μg/g-creatinine and 6.9 μg/g-creatinine, respectively; p=0.0001). When adjusted with generalized linear models for age, gender and z scores of body mass index, obese children having metabolic syndrome had significantly higher urinary BPA levels than obese children without metabolic syndrome and both obese groups had considerably elevated levels of urinary BPA than the controls (estimated marginal mean ± standard error: 42.3 ± 7.4 μg/g-creatinine, 22.6 ± 3.5 μg/g-creatinine and 12.1 ± 2.5 μg/g-creatinine, respectively, p=0.0001).

CONCLUSIONS

This study shows much higher BPA exposure among obese children with metabolic syndrome during the prepubertal period.

Effect of developmental exposure to bisphenol A on steroid hormone and vitamin D3 metabolism

High exposure to bisphenol A (BPA) in children has been associated with the outcomes of several diseases, including those related to developmental problems. To elucidate the mechanism of BPA mediated developmental toxicity, plasma and urine from rats exposed to BPA was analyzed with high resolution metabolomics, beginning from post-natal day 9, for 91 days. Female and male rats were orally administered 5 different BPA doses to elucidate dose- and sex-specific BPA effects. Regarding dose-specific effects, multivariate statistical analysis showed that metabolic shifts were considerably altered between 5, 50 and 250 mg BPA/kg bw/day in treated rats. A nonmonotonicity and monotonicity between BPA dose and metabolic response were major trajectories, showing overall metabolic changes in plasma and urine, respectively. Metabolic perturbation in the steroid hormone biosynthesis pathway was significantly associated with dose- and sex-specific BPA effects. Intermediate metabolites in the rate-limiting step of steroid hormone biosynthesis down-regulated steroid hormones in the 250 mg treatment. Further, our study identified that BPA increased urinary excretion of vitamin D₃ and decreased its concentration in blood, suggesting that perturbation of vitamin D₃ metabolism may be mechanistically associated with neurodevelopmental disorders caused by BPA. Three metabolites showed a decrease in sex difference with high BPA dose because female rats were more affected than males, which can be related with early puberty onset in female. In brief, the results demonstrated that BPA induces dose- and sex-specific metabolic shifts and that perturbation of metabolism can explain developmental problems.

Secular Trends in Pubertal Growth Acceleration in Swedish Boys Born From 1947 to 1996

IMPORTANCE

A secular trend for earlier menarcheal age has been established in girls but there are few studies of pubertal timing for boys.

OBJECTIVE

To determine if there is a secular trend for earlier pubertal timing among boys.

DESIGN, SETTING, AND PARTICIPANTS

For this population-based retrospective cohort study conducted in Gothenburg, Sweden, we collected heights and weights from school health records for boys born consecutively from January 1 and onwards in 1947 and every 5 years from 1951 to 1996 (n = 375 for each birth cohort from 1947-1991, n = 340 for the birth cohort in 1996, and n = 4090 for the total cohort). We estimated age at the peak height velocity (PHV), the maximum growth velocity during puberty, and childhood body mass index (BMI) at age 8 years for all study participants. The data were analyzed during 2018 and 2019. Boys were eligible if they had a complete personal identity number and data to calculate their age at PHV and childhood BMI. Approximately 2.4% of the original study population was excluded because they lacked a personal identity number, and in the remaining study population, 4090 (69%) had sufficient data to calculate childhood BMI and age at PHV.

EXPOSURES

The exposure was birth year and a potential confounding factor was childhood BMI.

MAIN OUTCOMES AND MEASURES

The outcome was age at PHV.

RESULTS

Of the 4090 participants, most were white and the mean (SD) age at PHV was 13.9 (1.1) years. A linear regression model revealed a significant association between year of birth and age at PHV. Age at PHV was 1.5 months earlier for every decade increase in birth year (95% CI, -1.72 to -1.19; P < .001). After adjusting for childhood BMI, age at PHV was 1.2 months earlier per decade increase in birth year (95% CI, -1.41 to -0.89). All analyses were repeated in the subgroup of boys born in Sweden and with parents born in Sweden with similar results, indicating that the secular trend was not explained by demographic changes in the population between 1947 and 1996.

CONCLUSIONS AND RELEVANCE

We provide evidence of a secular trend for earlier pubertal timing in boys that is partially explained by an increased childhood BMI, but other factors that are unknown contribute.

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.