Urinary bisphenol A, phthalate metabolites, and obesity: do gender and menopausal status matter?

Association between bisphenol A exposure and cardiometabolic outcomes: A longitudinal approach

Increased cardiometabolic risk is associated with abnormalities in blood biomarkers profile and adiposity measurements. Some substances found in the food matrix and the environment, called endocrine-disrupting chemicals, may impair cardiometabolic health in the early and later stages of life. Bisphenol A (BPA) is a food contaminant that migrates from food contact materials and may act as an endocrine disruptor, negatively affecting human health. The present work aims to longitudinally assess the association between BPA exposure and cardiometabolic outcomes, considering data from Portuguese population-based birth cohort Generation XXI. Blood insulin (0.06stdβ; 95 %CI:0.03,0.09) and insulin resistance (0.05stdβ; 95 %CI:0.02,0.08) presented a significant longitudinal association with BPA daily exposure after adjustment for important variables and energy. The same findings were observed for fat mass (0.03stdβ; 95 %CI 0.01,0.06) and waist circumference (0.06stdβ; 95 %CI:0.04,0.08). For z-BMI, a significant cross-sectional (0.03stdβ; 95 %CI:0.01,0.04) and longitudinal (0.02stdβ; 95 %CI:0.00,0.04) association was found. This was the first study assessing the association between BPA exposure and health outcomes from childhood to adolescence. We found an association between BPA exposure and increased blood insulin level, insulin resistance, fat mass percentage, waist circumference and z-BMI. Our results point to the need to reduce exposure to BPA in the early stages of life.

Metabolomics reveals that ferroptosis participates in bisphenol A-induced testicular injury

Objective

Bisphenol A (BPA) is a common environmental endocrine disruptor that negatively impairs male reproductive ability. This study aimed to explore the alterations in serum metabolomics that occur following BPA exposure and the mechanism via which BPA induces the death of testicular cells in a male mouse model.

Methods

The mice were classified into two groups: BPA-exposed and control groups, and samples were collected for metabolomic determination, semen quality analysis, electron microscopy, enzyme-linked immunosorbent assay, quantitative real-time PCR, pathological staining, and Western blot analysis.

Results

BPA exposure caused testicular damage and significantly decreased sperm quality in mice. Combined with non-target metabolomic analysis, this was closely related to ferroptosis induced by abnormal metabolites of arachidonic acid and phosphatidylcholine, and the expression of its related genes, acyl CoA synthetase 4, glutathione peroxidase 4, lysophosphatidylcholine acyltransferase 3, and phosphatidylethanolamine-binding protein 1 were altered.

Conclusion

BPA induced ferroptosis, caused testicular damage, and reduced fertility by affecting lipid metabolism in male mice. Inhibiting ferroptosis may potentially function as a therapeutic strategy to mitigate the male reproductive toxicity induced by BPA.

Association of Endocrine Disrupting Chemicals With the Metabolic Syndrome Among Women in the Multiethnic Cohort Study

Metabolic syndrome (MetS) is associated with a high risk of cardiovascular disease, a leading cause of death among women. MetS is a diagnosis of at least 3 of the following: high blood pressure, high fasting glucose, high triglycerides, high waist circumference, and low high-density lipoprotein cholesterol. Epidemiological studies suggest that endocrine disrupting chemical (EDC) exposure is positively associated with individual components of MetS, but evidence of an association between EDCs and MetS remains inconsistent. In a cross-sectional analysis within the Multiethnic Cohort Study, we evaluated the association between 4 classes of urinary EDCs (bisphenol A [BPA], triclosan, parabens, and phthalates) and MetS among 1728 women. Multivariable logistic regression was used to estimate odds ratios and 95% CI for the association between tertiles of each EDC and MetS adjusting for age, body mass index (BMI), racial and ethnic group, and breast cancer status. Stratified analyses by race and ethnicity and BMI were conducted. MetS was identified in 519 (30.0%) women. We did not detect statistically significant associations of MetS with BPA, triclosan, or phthalate metabolite excretion. MetS was inversely associated with total parabens (Ptrend = .002). Although there were suggestive inverse associations between EDCs and MetS among Latino and African American women, and women with BMI < 30 kg/m2, there was no statistically significant heterogeneity in associations by race and ethnicity or BMI. These findings suggest an inverse association between parabens and MetS in larger multiethnic studies. Prospective analyses to investigate suggested differences in associations by race, ethnicity, and BMI are warranted.

Association between phthalate exposure and obesity risk: A meta-analysis of observational studies

According to epidemiological studies, phthalate exposure is associated with an increased risk of obesity in children and adults; however, these observations remain debatable. Therefore, we performed a systematic review and meta-analysis of the current literature to explore the effects of phthalate exposure on obesity. A systematic search was performed from inception to July 2022 in PubMed, EMBASE, Scopus, and Web of Science. Quality assessment was completed using criteria modified from Newcastle-Ottawa Scale (NOS) for the included studies. Meta-analysis showed that childhood exposure to MnBP, MBP, MEP, MiBP, and MECPP was positively correlated with obesity. In adults, MMP, MEP, and MiBP were positively correlated with adult abdominal obesity, while MEHHP, MECPP, and MCOP were positively correlated with adult general obesity. Subgroup analysis revealed that the positive correlation was particularly significant in women, as well as in Europe and the United States. Overall, a substantial association exists between phthalate exposure and obesity in children and adults. Sex and study site may provide limited sources of heterogeneity.

Association of serum bisphenol A levels with incident overweight and obesity risk and the mediating effect of adiponectin

BACKGROUND

Existing cross-sectional studies indicated a positive association of bisphenol A (BPA) with overweight and obesity. However, the relationship and potential mechanisms underlying this association remain to be elucidated in prospective studies.

OBJECTIVE

This study was designed to investigate whether serum BPA is associated with incident overweight and obesity risk, and to further explore whether adiponectin plays a mediating role in the association.

METHODS

We measured blood BPA and adiponectin in Chinese populations. The association of serum BPA with overweight and obesity risk was evaluated using multivariable logistic regression models. We further examined the mediating effect of adiponectin by causal mediation analysis.

RESULTS

Among 796 participants free of overweight and obesity at baseline, 133 individuals developed overweight and obesity during the follow-up period. Compared with those in the lowest quartile of serum BPA, those in the second and third quartiles were positively associated with incident overweight and obesity risk adjusting for covariates (all P-values < 0.05), whereas this association was not observed in the fourth quartile. Further spline analysis showed an inverted U-shaped dose-response relationship (P_non-linear = 0.04). Furthermore, each unit of serum log₁₀-transformed BPA levels was associated with higher changes in waist-to-height ratio and body roundness index (all P-values < 0.05). Mediation analysis indicated significant indirect effects of adiponectin on the associations of BPA with overweight and obesity prevalence (mediation proportion: 46.08%; P = 0.02), and BMI levels (mediation proportion: 30.32%; P = 0.03).

CONCLUSION

Serum BPA displayed a positive association with incident overweight and obesity risk in a non-monotonic pattern, and adiponectin might mediate the association. Further mechanistic studies are warranted.

Endocrine disruptor chemicals as obesogen and diabetogen: Clinical and mechanistic evidence

Obesity is becoming an inevitable pandemic all over the world. The World Obesity Federation predicts in the 2022 World Obesity Atlas that one billion people worldwide, including 1 in 5 women and 1 in 7 men, will be living with obesity by 2030. Moreover, the prevalence of diabetes is increasing worldwide, and diabetes is becoming more of a public health problem. Increased insulin resistance due to obesity and deficiency in insulin secretion are the two main causes of type 2 diabetes mellitus (T2DM). An exogenous chemical or mixture of chemicals that interferes with any aspect of hormone action was defined as endocrine-disrupting chemicals (EDCs). Bisphenol A (BPA), the first known EDC, was synthesized and was considered to be estrogenic. Global production of BPA has increased progressively from 5 to 8 million tons (MT) between 2010 and 2016. Furthermore, researchers estimated that the production should reach 10.2 MT by 2022. The human population is exposed to EDCs in daily life in such forms as pesticides/herbicides, industrial and household products, plastics, detergents, and personal care products. The term obesogen was used for chemicals that promote weight gain and obesity by increasing the number of adipocytes and fat storage in existing adipocytes, changing the energy balance, and finally regulating appetite and satiety. Besides the obesogenic effect, EDCs can cause T2DM through alteration in ß cell function and morphology and insulin resistance. In this review, we provide clinical and mechanistic evidence regarding EDCs as obesogen and diabetogen. However, those studies are not enough methodologically to indicate causality. In this respect, randomized clinical trials are needed to investigate the association between obesogen, diabetogen and the related metabolic clinical picture.

TRIM65 Promotes Malignant Cell Behaviors in Triple-Negative Breast Cancer by Impairing the Stability of LATS1 Protein

TNBC is a malignant tumor that easily relapses and metastasizes, with a poor prognosis in women. Ubiquitination plays a key role in promoting the tumor process. In various tumors, TRIM65 can affect malignant biological tumor behavior by ubiquitination of related proteins. We aimed to investigate TRIM65 expression in TNBC and whether it promotes malignant biological behavior in TNBC cells using Cell Counting Kit-8, colony formation, and transwell assays. Mechanically, we confirmed that TRIM65 promoted TNBC invasion and metastasis by ubiquitination of LATS1 protein through Co-IP, CHX, and endogenous ubiquitination experiments. The expression of TRIM65 was abnormally high and accelerated the proliferation, invasion, and migration of MDA-MB-231 and MDA-MB-453 cells. In vivo animal experiments also revealed that TRIM65 accelerated TNBC cell proliferation. Mechanistically, TRIM65 degraded LATS1 protein expression through ubiquitination in the Co-IP, CHX, and endogenous ubiquitination experiments. Rescue assays confirmed that TRIM65 degraded LATS1 protein expression, accelerating the proliferation, invasion, and migration ability of TNBC cells. Our results show that TRIM65 is upregulated in TNBC, and TRIM65 degrades LATS1 protein expression through ubiquitination and promotes malignant biological behavior in TNBC cells. TRIM65 may play an important role as a new oncogene in TNBC.

Association of serum BPA levels with changes in lipid levels and dyslipidemia risk in middle-aged and elderly Chinese

Previous evidences exploring the associations of BPA with lipid changes and dyslipidemia did not obtain consistent results. To evaluate whether serum BPA concentration was associated with changes in blood lipid levels and incident dyslipidemia risk in middle-elderly Chinese adults, we conducted a prospective study with 1093 participants (average 62.65 years old) derived from the Dongfeng-Tongji cohort which was founded in 2008 and followed up each 5 years. Serum BPA levels were measured by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS). Changes in lipid levels were named as Δ lipids which equal to Lipid₂₀₁₃ - Lipid₂₀₀₈. The diagnosis of dyslipidemia was according to Chinese Guidelines on Prevention and Treatment of Dyslipidemia in 2016. We used multivariable linear regression and Logistic regression to explore the relations between serum BPA levels and changes in lipid levels and incident dyslipidemia risk, respectively. Besides, restricted cubic splines were used to explore the dose-response relations. After 5 years' follow-up, 51 individuals developed with hypercholesterolemia, 87 with hypertriglyceridemia, 34 with high-LDL-cholesterolemia, 74 with low-HDL-cholesterolemia, and 199 with dyslipidemia. At baseline serum BPA levels were positively related to TC, LDL-c, and Non-HDL-c levels. In the prospective study, each Ln-BPA increase was associated with 0.05 (95% CI: 0.02, 0.09) mmol/L increase in Δ TC, 0.07 (95% CI:0.03, 0.11) mmol/L increase in Δ Non-HDL-c, 0.05 (95% CI: 0.01, 0.08) increase in Δ TC/HDL-c, and 0.05 (95% CI: 0.01, 0.08) increase in Δ Non-HDL-c/HDL-c. We only observed significant associations in females but not in males. Besides, serum BPA levels were positively associated with hypercholesterolemia (OR=1.12, 95% CI: 1.01, 1.25). The restricted cubic splines obtained similar results. In conclusion, serum BPA was associated TC and Non-HDL-c changes, and BPA was also associated with increased risk of hypertriglyceridemia. Further prospective studies with large sample size are warranted to validate our findings.

The Role of Persistent Organic Pollutants in Obesity: A Review of Laboratory and Epidemiological Studies

Persistent organic pollutants (POPs) are considered as potential obesogens that may affect adipose tissue development and functioning, thus promoting obesity. However, various POPs may have different mechanisms of action. The objective of the present review is to discuss the key mechanisms linking exposure to POPs to adipose tissue dysfunction and obesity. Laboratory data clearly demonstrate that the mechanisms associated with the interference of exposure to POPs with obesity include: (a) dysregulation of adipogenesis regulators (PPARγ and C/EBPα); (b) affinity and binding to nuclear receptors; (c) epigenetic effects; and/or (d) proinflammatory activity. Although in vivo data are generally corroborative of the in vitro results, studies in living organisms have shown that the impact of POPs on adipogenesis is affected by biological factors such as sex, age, and period of exposure. Epidemiological data demonstrate a significant association between exposure to POPs and obesity and obesity-associated metabolic disturbances (e.g., type 2 diabetes mellitus and metabolic syndrome), although the existing data are considered insufficient. In conclusion, both laboratory and epidemiological data underline the significant role of POPs as environmental obesogens. However, further studies are required to better characterize both the mechanisms and the dose/concentration-response effects of exposure to POPs in the development of obesity and other metabolic diseases.

Urinary phthalate metabolites and alternatives and serum sex steroid hormones among pre- and postmenopausal women from NHANES, 2013-16

BACKGROUND

Exposure to phthalates is ubiquitous across the United States. While phthalates have anti-androgenic effects in men, there is little research on their potential impacts on sex hormone concentrations in women and that also take into account menopausal status.

METHODS

Cross-sectional data on urinary phthalate metabolites, serum sex hormones, and relevant covariates were obtained from the National Health and Nutrition Examination Survey 2013-14 and 2015-16. Women over the age of 20 who were not pregnant or breastfeeding and had not undergone oophorectomy were included (n = 698 premenopausal, n = 557 postmenopausal). Weighted multivariable linear and Tobit regression models stratified by menopausal status were fit with natural log-transformed phthalate concentrations and sex hormone outcomes adjusting for relevant covariates.

RESULTS

Phthalate metabolites were associated with differences in sex hormone concentrations among postmenopausal women only. Di-2-ethylhexyl phthalate (DEHP) was associated with lower serum estradiol and bioavailable testosterone concentrations. Specifically, a doubling of DEHP concentrations was associated with 5.9% (95% Confidence Interval (CI): 0.2%, 11.3%) lower estradiol and 6.2% (95% CI: 0.0%, 12.1%) lower bioavailable testosterone concentrations. In contrast, 1,2-cyclohexane dicarboxylic acid di-isononyl ester (DINCH) was associated with higher free testosterone, bioavailable testosterone, and free androgen index. Finally, di-2-ethylhexyl terephthalate (DEHTP) was associated with a higher testosterone-to-estradiol ratio. None of these results retained statistical significance when adjusted for multiple comparisons.

CONCLUSIONS

DEHP, DINCH, and DEHTP were associated with differences in serum sex hormone concentrations among postmenopausal women, highlighting the need for further research into the safety of these chemicals.

Phthalate exposures and one-year change in body mass index across the menopausal transition

BACKGROUND

The menopausal transition is a hormonally sensitive period associated with changes in body weight. Phthalates are ubiquitous endocrine disrupting chemicals that could disrupt weight homeostasis, but it is unknown whether this occurs during the menopausal transition.

OBJECTIVES

Our objectives were to (1) determine if phthalate exposure in pre- and perimenopausal women was associated with one-year change in body mass index (BMI), and (2) determine if these associations differed across the menopausal transition.

METHODS

We addressed our objectives using data from 524 participants enrolled in the Midlife Women's Health Study. We calculated change in BMI from baseline to first follow-up visit approximately one year later. Phthalate exposures were approximated by measuring urinary metabolites in pools of two-to-four spot urine samples collected across a four-week period at baseline. We molar-converted and summed mono-(2-ethylhexyl) phthalate (mEHP), mono (2-ethyl-5-hydroxyhexyl) phthalate (mEHHP), mono (2-ethyl-5-oxohexyl) phthalate (mEOHP), and mono (2-ethyl-5-carboxypentyl) phthalate (mECPP) to approximate exposure to di-(2-ethylhexyl) phthalate (∑DEHP); ∑DEHP, mono (3-carboxypropyl) phthalate (mCPP), and monobenzyl phthalate (mBzP) to approximate exposure to plasticizer phthalates (∑Plastics); and monoethyl phthalate (mEP), monobutyl phthalate (mBP), and monoisobutyl phthalate (miBP) to approximate exposure to phthalates from personal care products (∑PCP). We used multivariable linear regression models to evaluate associations of specific gravity-adjusted ln-transformed phthalate metabolites or sums with one-year BMI change, and also considered whether associations differed depending on each woman's menopausal status change from baseline to first follow-up.

RESULTS

At baseline, most women were premenopausal (67.8%), non-Hispanic white (67.9%), and college educated (65.8%). Overall, urinary phthalate metabolites or sums were not associated with one-year BMI change. Stratified analysis identified positive associations between ∑DEHP (and three of its metabolites: MEHP, MEHHP, and MEOHP) and one-year BMI change among women who transitioned from peri-to post-menopause from baseline to first follow-up. For example, in these women, with each doubling of ∑DEHP, BMI increased by 0.65 kg/m² (95%CI: 0.17, 1.13) from baseline to first follow-up. Personal care product-associated phthalate metabolites (mBP and mEP) were negatively associated with one-year BMI change among women who remained perimenopausal from baseline to first follow-up, while miBP and mEP were positively associated with one-year BMI change among women who transitioned from peri-to post-menopause.

CONCLUSION

We found the strongest associations between some phthalates and one-year BMI change in women who transitioned from peri-to post-menopause from baseline to first follow-up. This supports previous evidence that the menopausal transition is a hormonally sensitive period in women's lives. To establish whether phthalate exposure contributes to body weight changes associated with the menopausal transition, substantially more research is needed to corroborate our findings.

Life-Time Environmental Chemical Exposure and Obesity: Review of Epidemiological Studies Using Human Biomonitoring Methods

The exponential global increase in the incidence of obesity may be partly attributable to environmental chemical (EC) exposure. Humans are constantly exposed to ECs, primarily through environmental components. This review compiled human epidemiological study findings of associations between blood and/or urinary exposure levels of ECs and anthropometric overweight and obesity indices. The findings reveal research gaps that should be addressed. We searched MEDLINE (PubMed) for full text English articles published in 2006-2020 using the keywords "environmental exposure" and "obesity". A total of 821 articles were retrieved; 102 reported relationships between environmental exposure and obesity indices. ECs were the predominantly studied environmental exposure compounds. The ECs were grouped into phenols, phthalates, and persistent organic pollutants (POPs) to evaluate obesogenic roles. In total, 106 articles meeting the inclusion criteria were summarized after an additional search by each group of EC combined with obesity in the PubMed and Scopus databases. Dose-dependent positive associations between bisphenol A (BPA) and various obesity indices were revealed. Both individual and summed di(2-ethylhexyl) phthalate (DEHP) and non-DEHP metabolites showed inconsistent associations with overweight and obesity indices, although mono-butyl phthalate (MBP), mono-ethyl phthalate (MEP), and mono-benzyl phthalate (MBzP) seem to have obesogenic roles in adolescents, adults, and the elderly. Maternal exposure levels of individual POP metabolites or congeners showed inconsistent associations, whereas dichlorodiphenyldichloroethylene (DDE) and perfluorooctanoic acid (PFOA) were positively associated with obesity indices. There was insufficient evidence of associations between early childhood EC exposure and the subsequent development of overweight and obesity in late childhood. Overall, human evidence explicitly reveals the consistent obesogenic roles of BPA, DDE, and PFOA, but inconsistent roles of phthalate metabolites and other POPs. Further prospective studies may yield deeper insights into the overall scenario.