Factors affecting interpretation of national biomonitoring data from multiple countries: BPA as a case study

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.

Analysis of chemical exposures in racial populations in Canada: An investigation based on the Canadian health measures survey

Despite demonstrated disparities in environmental chemical exposures by racial identity, no Canadian study has systematically assessed the feasibility of using a nationally representative dataset to examine differences in chemical concentrations by race. We assessed the feasibility and constraints of analysing chemical exposures in racial populations, including visible minorities and populations of Indigenous identity, using biomonitoring data collected through the Canadian Health Measures Survey (CHMS). Our primary objectives were to assess the ability to 1) generate geometric means and percentiles of chemical concentrations for racial populations by age or sex, 2) statistically compare concentrations among racial populations, and 3) calculate time trends of concentrations by race. We conducted these analyses for several priority chemicals: lead, cadmium, benzene, bisphenol A (BPA), and di(2-ethylhexyl) phthalate (DEHP). Survey participants self-identified as one of the following: White, Black, East and Southeast Asian, South Asian, Middle Eastern, Latin American, First Nations, Metis, and Inuit. Analyses were conducted for individual and combined cycles of the CHMS. Using data from the latest CHMS cycle in which each chemical was measured, we observed that sample sizes were sufficient to report geometric mean concentrations for all races except Inuit. Due to privacy considerations associated with small sample sizes, the 5th and 95th percentile concentrations could not be consistently reported for all racial populations in this analysis. While we were able to statistically compare concentrations among racial populations, the analysis was constrained by the limited number of statistical degrees of freedom available in a single CHMS cycle. Both of these constraints were alleviated by combining multiple cycles of data. The analysis of time trends was less subject to privacy and statistical limitations; we were able to calculate time trends of chemical concentrations for all racial populations. Our findings provide an important baseline for follow-up investigations of descriptive and etiological analyses of environmental chemical exposures and race in the CHMS.

Urinary concentrations of environmental phenol among pregnant women in the Japan Environment and Children's Study

Humans are exposed to various bisphenols, alkylphenols and nitrophenols through dietary intake, food packaging and container materials, indoor and outdoor air/dust. This study aimed to evaluate exposure of Japanese pregnant women to environmental phenols by measuring target compounds in urine samples. From a cohort of the Japan Environment and Children's Study, 4577 pregnant women were selected. Bisphenol A (BPA), bisphenol S (BPS), bisphenol F (BPF), bisphenol AF (BPAF), para-nitrophenol (PNP), 3-methyl-4-nitrophenol (PNMC), branched 4-nonylphenol (4-NP), linear 4-nonylphenol and 4-tert-octylphenol (4-t-OP) were analysed using a high-performance liquid chromatograph coupled to a triple-quadrupole mass spectrometer. The urinary metabolite data were combined with a questionnaire to examine the determinants of phenol exposure by machine learning. The estimated daily intake (EDI) and hazard quotient (HQ) of BPA were calculated. PNP (68.2%) and BPA (71.5%) had the highest detection frequencies, with median concentrations of 0.76 and 0.46 μg/g creatinine, respectively. PNMC, BPS, BPF and 4-NP were determined in 24.9%, 11.9%, 1.3% and 0.4% of samples, respectively, whereas BPAF (0.02%) and 4-t-OP (0.02%) were only determined in a few samples. The PNP concentrations measured in this study were comparable with those reported in previous studies, whereas the BPA concentrations were lower than those reported previously worldwide. The EDI of BPA was 0.014 μg/kg body weight/day. Compared with the tolerable daily intake set by the German Federal Institute for Risk Assessment, the median (95th percentile) HQ was 0.044 (0.2). This indicates that the observed levels of BPA exposure pose a negligible health risk to Japanese pregnant women. Determinants of bisphenol and nitrophenol exposure could not be identified by analysing the questionnaire solely, suggesting that biological measurement is necessary to assess exposure of pregnant women to bisphenols and nitrophenols. This is the first study to report environmental phenol exposure of Japanese pregnant women on a nationwide scale.

Risk assessment of bisphenol A (BPA) in Irish meat and meat products

Bisphenol A (BPA) is a chemical with large-scale applications in the manufacturing of industrial products. Concerns have been raised regarding human exposure to BPA and dietary consumption is the main route of exposure. BPA is recognised as an endocrine disruptor with multiple adverse effects on the reproductive, immune, and nervous systems. This study aimed to conduct a probabilistic risk assessment to evaluate the human health risk based on the raw concentration data (N = 1266) of BPA in non-canned meat and meat products purchased from supermarkets and local butchers in Dublin and the surrounding area. The mean exposure levels for BPA in non-canned meat and meat products, fresh meat, and processed meat products among children were 0.019, 0.0022, and 0.015 μg (kg bw)^-1 day^-1, respectively. Therefore, simulated human exposures to BPA were far below the EFSA recommended current temporary tolerable daily intake (t-TDI) of 4 μg (kg bw)^-1 day^-1. However recently, the EFSA has proposed a draft TDI of 0.04 ng (kg bw)^-1 day^-1 to replace the current t-TDI. Hence, our results indicated potential health concerns as the estimated exposure levels (5th-95th percentile) were below current t-TDI but above draft TDIs. Further investigation into the source of BPA contamination in processed meat products is highly recommended. The research presented here will inform the public, meat producers and processors, and policymakers on potential exposure to BPA.

Systematic review of the potential carcinogenicity of bisphenol A in humans

Bisphenol A (BPA) is a synthetic chemical to which humans are exposed through a variety of environmental sources. We have conducted a comprehensive, systematic review of 29 epidemiology studies and 27 experimental animal studies, published through May 2022, evaluating the potential carcinogenicity of BPA to contribute to the understanding of whether BPA is carcinogenic in humans. We conducted this review according to best practices for systematic reviews and incorporating established frameworks for study quality evaluation and evidence integration. The epidemiology studies have many limitations that increase the risk of biased results, but overall, the studies do not provide clear and consistent evidence for an association between BPA exposure and the development of any type of cancer. The experimental animal studies also do not provide strong and consistent evidence that BPA is associated with the induction of any malignant tumor type. Some of the proposed mechanisms for BPA carcinogenicity are biologically plausible, but the relevance to human exposures is not clear. We conclude that there is inadequate evidence to support a causal relationship between BPA exposure and human carcinogenicity, based on inadequate evidence in humans, as well as evidence from experimental animal studies that suggests a causal relationship is not likely.

Urinary Levels of 14 Metal Elements in General Population: A Region-Based Exploratory Study in China

Metal pollution may lead to a variety of diseases; for this reason, it has become a matter of public concern worldwide. However, it is necessary to use biomonitoring approaches to assess the risks posed to human health by metals. In this study, the concentrations of 14 metal elements in 181 urine samples obtained from the general population of Gansu Province, China, were analyzed using inductively coupled plasma mass spectrometry. Eleven out of fourteen target elements had detection frequencies above 85%, namely, Cr, Ni, As, Se, Cd, Al, Fe, Cu and Rb. The concentrations of most metal elements in the urine of our subjects corresponded to the medium levels of subjects in other regional studies. Gender exerted a significant influence (p < 0.05) on the concentrations of Tl, Rb and Zn. The concentrations of Ni, As, Pb, Sr, Tl, Zn, Cu and Se showed significant differences among different age groups and the age-related concentration trends varied among these elements. There were significant differences in the urine concentrations of Zn and Sr between those subjects in the group who were frequently exposed to soil (exposed soil > 20 min/day) and those in the group who were not, indicating that people in regular contact with soil may be more exposed to metals. This study provides useful information for evaluating the levels of metal exposure among general populations.

A cross-validation based approach for estimating specific gravity in elementary-school aged children using a nonlinear model

Environmental research often relies on urinary biomarkers which require dilution correction to accurately measure exposures. Specific gravity (SG) and creatinine (UCr) are commonly measured urinary dilution factors. Epidemiologic studies may assess only one of these measures, making it difficult to pool studies that may otherwise be able to be combined. Participants from the National Health and Nutrition Examination Survey 2007-2008 cycle were used to perform k-fold validation of a nonlinear model estimating SG from UCr. The final estimated model was applied to participants from the School Inner-City Asthma Intervention Study, who submitted urinary samples to the Children's Health Exposure Analysis Resource. Model performance was evaluated using calibration metrics to determine how closely the average estimated SG was to the measured SG. Additional models, with interaction terms for age, sex, body mass index, race/ethnicity, relative time of day when sample was collected, log transformed 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), and asthma status were estimated and assessed for improvement. The association between monobenzyl phthalate (MBZP) and asthma symptom days, controlling for measured UCr, measured SG, and each estimated SG were compared to assess validity of the estimated SG. The model estimating SG from UCr alone, resulted in a beta estimate of 1.10 (95% CI: 1.01, 1.19), indicating agreement between model-predicted SG and measured SG. Inclusion of age and sex in the model improved estimation (β = 1.06, 95% CI: 0.98, 1.15). The full model accounting for all interaction terms with UCr resulted in the best agreement (β = 1.01, 95% CI: 0.93,1.09). Associations between MBZP and asthma symptoms days, controlling for each estimated SG, were within the range of effect estimates when controlling for measured SG and measured UCr (Rate ratios = 1.28-1.34). Our nonlinear modeling provides opportunities to estimate SG in studies that measure UCr or vice versa, enabling data pooling despite differences in urine dilution factors.

Diet quality and exposure to endocrine-disrupting chemicals among US adults

Human exposure to endocrine-disrupting chemicals (EDCs) may increase risk for chronic disease. Diet is a significant source of EDC exposure, yet healthy diets recommended for chronic disease prevention have not been thoroughly examined for associations with EDC exposure. Using data from the National Health and Nutrition Examination Survey 2013-2016, we examined associations of dietary patterns with exposure to non-persistent EDCs potentially consumed through diet. EDCs were measured in spot urine samples. Diet was assessed using 24-h recalls. Multivariable linear regression was used to examine associations of three healthy diet scores [Healthy Eating Index (HEI), relative Mediterranean Diet (rMED), and Dietary Approaches to Stop Hypertension] and fast-food consumption with EDCs. In fully adjusted models, no diet was associated with exposure to the bisphenols, phthalates, or polycyclic aromatic hydrocarbons examined. A 1-point increase in rMED (of 18 possible points) was associated with 2.7% (95% CI: 1.7%, 3.8%) greater urinary nitrate. A 10-point increase in HEI (of 100 possible points) was associated with 5.3% (95% CI: 2.8%, 7.9%) greater nitrate and 6.8% (95% CI: 4.5%, 9.2%) greater perchlorate. Because perchlorate and nitrate can disrupt thyroid hormone production, we conducted an exploratory analysis to examine whether these chemicals mediate an association between diet and thyroid hormones. A 10-point increase in HEI was associated with 0.6% reduced serum total thyroxine (95% CI: 1.7%, 0.5%) among all adults, with 57.5% of the effect explained by perchlorate. Nitrate mediated an association of rMED with modestly reduced total triiodothyronine among females. Most EDCs examined had no association with the diets evaluated, indicating that recommended healthy diets were not protective against EDC exposures. As observed with two thyroid antagonists, some recommended diets may increase EDC exposures and related adverse health outcomes. Additional work should identify effective food production and processing practices to reduce dietary exposures to potentially harmful EDCs.

Increased gut serotonin production in response to bisphenol A structural analogs may contribute to their obesogenic effects

Obesogens are synthetic, environmental chemicals that can disrupt endocrine control of metabolism and contribute to the risk of obesity and metabolic disease. Bisphenol A (BPA) is one of the most studied obesogens. There is considerable evidence that BPA exposure is associated with weight gain, increased adiposity, poor blood glucose control, and nonalcoholic fatty liver disease in animal models and human populations. Increased usage of structural analogs of BPA has occurred in response to legislation banning their use in some commercial products. However, BPA analogs may also cause some of the same metabolic impairments because of common mechanisms of action. One key effector that is altered by BPA and its analogs is serotonin, however, it is unknown if BPA-induced changes in peripheral serotonin pathways underlie metabolic perturbations seen with BPA exposure. Upon ingestion, BPA and its analogs act as endocrine-disrupting chemicals in the gastrointestinal tract to influence serotonin production by the gut, where over 95% of serotonin is produced. The purpose of this review is to evaluate how BPA and its analogs alter gut serotonin regulation and then discuss how disruption of serotonergic networks influences host metabolism. We also provide evidence that BPA and its analogs enhance serotonin production in gut enterochromaffin cells. Taken together, we propose that BPA and many BPA analogs represent endocrine-disrupting chemicals that can influence host metabolism through the endogenous production of gut-derived factors, such as serotonin.

Harmonization of Human Biomonitoring Studies in Europe: Characteristics of the HBM4EU-Aligned Studies Participants

Human biomonitoring has become a pivotal tool for supporting chemicals' policies. It provides information on real-life human exposures and is increasingly used to prioritize chemicals of health concern and to evaluate the success of chemical policies. Europe has launched the ambitious REACH program in 2007 to improve the protection of human health and the environment. In October 2020 the EU commission published its new chemicals strategy for sustainability towards a toxic-free environment. The European Parliament called upon the commission to collect human biomonitoring data to support chemical's risk assessment and risk management. This manuscript describes the organization of the first HBM4EU-aligned studies that obtain comparable human biomonitoring (HBM) data of European citizens to monitor their internal exposure to environmental chemicals. The HBM4EU-aligned studies build on existing HBM capacity in Europe by aligning national or regional HBM studies. The HBM4EU-aligned studies focus on three age groups: children, teenagers, and adults. The participants are recruited between 2014 and 2021 in 11 to 12 primary sampling units that are geographically distributed across Europe. Urine samples are collected in all age groups, and blood samples are collected in children and teenagers. Auxiliary information on socio-demographics, lifestyle, health status, environment, and diet is collected using questionnaires. In total, biological samples from 3137 children aged 6-12 years are collected for the analysis of biomarkers for phthalates, HEXAMOLL® DINCH, and flame retardants. Samples from 2950 teenagers aged 12-18 years are collected for the analysis of biomarkers for phthalates, Hexamoll® DINCH, and per- and polyfluoroalkyl substances (PFASs), and samples from 3522 adults aged 20-39 years are collected for the analysis of cadmium, bisphenols, and metabolites of polyaromatic hydrocarbons (PAHs). The children's group consists of 50.4% boys and 49.5% girls, of which 44.1% live in cities, 29.0% live in towns/suburbs, and 26.8% live in rural areas. The teenagers' group includes 50.6% girls and 49.4% boys, with 37.7% of residents in cities, 31.2% in towns/suburbs, and 30.2% in rural areas. The adult group consists of 52.6% women and 47.4% men, 71.9% live in cities, 14.2% in towns/suburbs, and only 13.4% live in rural areas. The study population approaches the characteristics of the general European population based on age-matched EUROSTAT EU-28, 2017 data; however, individuals who obtained no to lower educational level (ISCED 0-2) are underrepresented. The data on internal human exposure to priority chemicals from this unique cohort will provide a baseline for Europe's strategy towards a non-toxic environment and challenges and recommendations to improve the sampling frame for future EU-wide HBM surveys are discussed.

Bisphenol A Exposure in Exclusively Breastfed Infants and Lactating Women: An Observational Cross-sectional Study

OBJECTIVE

Bisphenol A (BPA) is a known endocrine disruptor and free BPA will interact with estrogen. BPA is also fat soluble and will therefore contaminate breast milk. The European Food Safety Authority has set a limit for temporary tolerable daily intake of 4 μg/kg body weight/day in breastfeeding infants. The aim of this study was to measure human milk BPA concentrations in Turkish women and thus exclusively breastfed infants’ exposure to BPA.

METHODS

Healthy, postnatal, exclusively breastfeeding women were recruited and breast milk samples were collected. Free BPA concentration was analyzed in the milk samples using competitive enzyme-linked immunosorbent assay. Participants’ demographic characteristics and nutritional habits were investigated through face-to-face interviews using a detailed questionnaire.

RESULTS

Eighty women participated. Median milk free BPA level was 0.63 μg/L. There was no statistically significant association between maternal body mass index, birth type, parity, infant birth week, infant birth weight, and human milk BPA concentration. Nevertheless, there was a significant association between human milk BPA level and consumption of fast-food and carbonated drinks (p=0.022 and p=0.018, respectively). Exclusively breastfed infants’ mean BPA exposure was 0.0099±0.0079 μg/kg bw/day. There was a moderate negative significant correlation between infant BPA exposure and infant current body weight (r=0.327, p=0.003).

CONCLUSION

BPA exposure in exclusively breastfed infants was within accepted limits and the current dietary exposure level of infants in this cohort was safe.

The internal exposure of bisphenol analogues in South China adults and the associated health risks

Bisphenol A (BPA) is widely applied in industrial products and household products, leading to ubiquitous occurrences in environmental and biological samples. However, knowledge on human internal exposure to bisphenol analogues remains limited. Our study determined nine bisphenol analogues in urine samples collected from 1168 South China adults. BPA and bisphenol F (BPF) exhibited the highest detection frequencies in urine, i.e., 99.4% and 74.6%, respectively. BPA dominated over other analogues, with a median concentration of 1.74 μg/L, while BPF had a median concentration of 0.08 μg/L. Significant positive correlation was observed between urinary BPA and BPF (r = 0.201, p < 0.01), indicating similar exposure sources or pathways of these two chemicals. Urinary BPA concentrations were significantly correlated with age, marital status, drinking status and history of hyperlipidemia (p < 0.05). The median estimated daily intake (EDI) of Σ₃BPs (the sum concentrations of BPA, BPF and BPAF) was determined to be 53.6 ng/kg-bw/day for adults. The EDIs were much lower than the temporary tolerable reference dose of BPA recommended by the European Food Safety Authority, indicating the bisphenol analogues presented no obvious health risks to South China adults.

Italian Children Exposure to Bisphenol A: Biomonitoring Data from the LIFE PERSUADED Project

A human biomonitoring (HBM) study on bisphenol A (BPA) in Italian children and adolescents was performed within the LIFE PERSUADED project, considering the residing areas, sex and age. The median urinary BPA level was 7.02 µg/L, with children living in the South of Italy or in urban areas having higher levels than those residing in the North or in rural areas. Children aged 4–6 years had higher BPA levels than those aged 7–10 and 11–14 years, but no differences were detected between sexes. The exposure in Italian children was higher compared to children from other countries, but lower than the HBM guidance value (135 µg/L). The estimated daily intake was 0.17 μg/kg body weight (bw) per day, about 24-fold below the temporary Tolerable Daily Intake of 4 μg/kg bw per day established by the European Food Safety Authority. However, this threshold was exceeded in 1.44% of the enrolled children, raising concern about the overall exposure of Italian young population.

Human biomonitoring of toxic and essential metals in younger elderly, octogenarians, nonagenarians and centenarians: Analysis of the Healthy Ageing and Biomarkers Cohort Study (HABCS) in China

BACKGROUND

Metals can be either toxic or essential to health, as they play different role in oxidative stress and metabolic homeostasis during the ageing process. Population-based biomonitoring have documented levels and ranges in concentrations among general population of 0-79 years of age. In people aged 80 and above, toxic metals and essential metals may have different risk profiles, and thus need to be better studied.

OBJECTIVE

Our aim is to investigate concentrations of toxic metals (arsenic, cadmium, lead and mercury) and essential metals (chromium, cobalt, molybdenum, manganese, nickel and selenium) and their role in diseases, nutritional status among younger elderly, octogenarians, nonagenarians and centenarians.

METHODS

A total of 932 younger elderly, 643 octogenarians, 540 nonagenarians, 386 centenarians were included from the cross-sectional Healthy Aging and Biomarkers Cohort Study in 2017-2018. Blood or urine biological substrates were collected from each participant to determine the concentrations of toxic metals and essential metals by inductively coupled plasma mass spectrometry. Random forest was constructed to rank the importance of toxic metals and essential metals in longevity. LASSO penalized regressions were performed to select the most significant metals associated with diseases and nutritional status, of which simultaneously included all metals and adjusted for the confounding factors.

RESULTS

Compared to women, we found higher biomarker concentrations in men for toxic metals (41.2 µg/L vs 34.4 µg/L for blood lead, 1.56 µg/L vs 1.19 µg/L for blood mercury) and lower concentration of essential metals (0.48 µg/L vs 0.58 µg/L for blood molybdenum, 10.0 µg/L vs 11.1 µg/L for blood manganese). These factors may contribute to gender difference observed in longevity, that women live longer than men. Blood lead and urine cadmium tended to increase with age (P <0.001); blood cobalt, molybdenum, manganese increased with age, blood selenium decreased with age while the prevalence of selenium deficiency was extremely low in centenarians. Among toxic metals and essential metals, LASSO penalized regression identified the most significant metals associated with chronic kidney disease was cadmium and arsenic; and it was manganese, cobalt, and selenium for diabetes; it was selenium, molybdenum, lead for anemia; it was mercury for underweight. In random forest model, the top four important metals in longevity were selenium, arsenic, lead and manganese both in men and women.

CONCLUSIONS

Generally, toxic metals levels were significantly higher while essential metals were relatively sufficient in Chinese centenarians. Toxic metals and essential metals played different role in diseases, nutritional status and longevity in the process of aging. Our research provided real world evidence of biomonitoring reference values to be used for the ongoing population health surveillance in longevity.

Trends in environmental chemical concentrations in the Canadian population: Biomonitoring data from the Canadian Health Measures Survey 2007-2017

Ten years of nationally representative biomonitoring data collected between 2007 and 2017 are available from the Canadian Health Measures Survey (CHMS). These data establish baseline environmental chemical concentrations in the general population. Here we sought to evaluate temporal trends in environmental chemical exposures in the Canadian population by quantifying changes in biomarker concentrations measured in the first five two-year cycles of the CHMS. We identified 39 chemicals that were measured in blood or urine in at least three cycles and had detection rates over 50% in the Canadian population. We calculated geometric mean concentrations for each cycle using the survey weights provided. We then conducted analyses of variance to test for linear trends over all cycles. We also calculated the percent difference in geometric means between the first and most recent cycle measured. Of the 39 chemicals examined, we found statistically significant trends across cycles for 21 chemicals. Trends were decreasing for 19 chemicals from diverse chemical groups, including metals and trace elements, phenols and parabens, organophosphate pesticides, per- and polyfluoroalkyl substances, and plasticizers. Significant reductions in chemical concentrations included di-2-ethylhexyl phthalate (DEHP; 75% decrease), perfluorooctane sulfate (PFOS; 61% decrease), perfluorooctanoic acid (PFOA; 58% decrease), dimethylphosphate (DMP; 40% decrease), lead (33% decrease), and bisphenol A (BPA; 32% decrease). Trends were increasing for two pyrethroid pesticide metabolites, including a 110% increase between 2007 and 2017 for 3-phenoxybenzoic acid (3-PBA). No significant trends were observed for the remaining 18 chemicals that included arsenic, mercury, fluoride, acrylamide, volatile organic compounds, and polycyclic aromatic hydrocarbons. National biomonitoring data indicate that concentrations, and therefore exposures, have decreased for many priority chemicals in the Canadian population. Concentrations for other chemical groups have not changed or have increased, although average concentrations remain below thresholds of concern derived from human exposure guidance values. Continued collection of national biomonitoring data is necessary to monitor trends in exposures over time.

Estimation of lactating mothers' daily intakes of bisphenol A using breast milk

Breast milk is a unique biological sample that reflects the exposure levels of both lactating mothers and infants. The exposure levels of BPA due to breast milk consumption for infants can be estimated easily, but the method to estimate the total daily intake (TDI) of lactating mothers from breast milk has not yet been established. In this study, BPA concentrations were detected in breast milk samples from 149 lactating mothers from Hunan, China. The median concentration of BPA in breast milk was 0.053 μg/L with a range of 0.001-2.535 μg/L, and a temporal decline trend was found for BPA concentrations in breast milk (p < 0.05). The median intake of BPA via breast milk was 26.8 ng/kg bw/day for 0-3-month-old infants and 7.0 ng/kg bw/day for 4-12-month-old infants. Based on the predicted concentrations of BPA in urine and blood via the conversion coefficients from breast milk, the TDIs of lactating mothers were estimated. The TDIs estimated from the simulated urine concentration were 84.0 ± 175.2 ng/kg bw/day for 0-3-month-old infants' mothers and 36.9 ± 80.8 ng/kg bw/day for 4-12-month-old infants' mothers. The dietary daily intakes estimated from the simulated blood concentration were 579.6 ± 370.8 ng/kg bw/day for 0-3-month-old infants' mothers and 280.1 ± 195.2 ng/kg bw/day for 4-12-month-old infants' mothers. When assuming the dietary daily intakes in Hunan of the fifth total diet study (TDS) as the "true" total dietary intake of our population, the contribution of diet was estimated to be 63.7%, which suggested that non-dietary BPA exposure may be underestimated.

Human-Biomonitoring derived exposure and Daily Intakes of Bisphenol A and their associations with neurodevelopmental outcomes among children of the Polish Mother and Child Cohort Study

BACKGROUND

Bisphenol A (BPA) is an industrial chemical mostly used in the manufacture of plastics, resins and thermal paper. Several studies have reported adverse health effects with BPA exposures, namely metabolic disorders and altered neurodevelopment in children, among others. The aim of this study was to explore BPA exposure, its socio-demographic and life-style related determinants, and its association with neurodevelopmental outcomes in early school age children from Poland.

METHODS

A total of 250 urine samples of 7 year-old children from the Polish Mother and Child Cohort Study (REPRO_PL) were analyzed for BPA concentrations using high performance liquid chromatography with online sample clean-up coupled to tandem mass spectrometry (online-SPE-LC-MS/MS). Socio-demographic and lifestyle-related data was collected by questionnaires or additional biomarker measurements. Emotional and behavioral symptoms in children were assessed using mother-reported Strengths and Difficulties Questionnaire (SDQ). Cognitive and psychomotor development was evaluated by Polish adaptation of the Intelligence and Development Scales (IDS) performed by trained psychologists.

RESULTS

Urinary BPA concentrations and back-calculated daily intakes (medians of 1.8 μg/l and 46.3 ng/kg bw/day, respectively) were similar to other European studies. Urinary cotinine levels and body mass index, together with maternal educational level and socio-economic status, were the main determinants of BPA levels in Polish children. After adjusting for confounding factors, BPA has been found to be positively associated with emotional symptoms (β: 0.14, 95% CI: 0.022; 0.27). Cognitive and psychomotor development were not found to be related to BPA levels.

CONCLUSIONS

This study represents the first report of BPA levels and their determinants in school age children in Poland. The exposure level was found to be related to child emotional condition, which can have long-term consequences including social functioning and scholastic achievements. Further monitoring of this population in terms of overall chemical exposure is required.

Temporal exposure and consistency of endocrine disrupting chemicals in a longitudinal study of individuals with impaired fasting glucose

Endocrine disrupting chemicals (EDCs) include non-persistent exogenous substances such as parabens, bisphenols and phthalates which have been associated with a range of metabolic disorders and disease. It is unclear if exposure remains consistent over time. We investigated change in indicators of EDC exposure between 2009 and 2016 and assessed its consistency between and within individuals over a median follow-up time of 47 months in a sample of Dutch individuals. Of 500 Dutch individuals, two 24 h urine samples were analysed for 5 parabens, 3 bisphenols and 13 metabolites of in total 8 different phthalates. We calculated per-year differences using meta-analysis and assessed temporal correlations between and within individuals using Spearman correlation coefficients, intra-class correlation coefficients (ICC) and kappa-statistics. We found a secular decrease in concentrations of methyl, ethyl, propyl and n-butyl paraben, bisphenol A, and metabolites of di-ethyl phthalate (DEP), di-butyl phthalate (DBP), di-(2-ethyl-hexyl) phthalate (DEHP), and butylbenzyl phthalate (DBzP) which varied from 8 to 96% (ethyl paraben, propyl paraben) between 2009 and 2016. Within-person temporal correlations were highest for parabens (ICC: 0.34 to 0.40) and poorest for bisphenols (ICC: 0.15 to 0.23). For phthalate metabolites, correlations decreased most between time periods (ICC < 48 months: 0.22 to 0.39; ≥48 months: 0.05 to 0.32). When categorizing EDC concentrations, 33-54% of individuals remained in the lowest or highest category and temporal correlations were similar to continuous measurements. Exposure to most EDCs decreased between 2009 and 2016 in a sample of individuals with impaired fasting glucose from the Dutch population. Temporal consistency was generally poor. The inconsistency in disease associations may be influenced by individual-level or temporal variation exhibited by EDCs. Our findings call for the need for repeated measurements of EDCs in observational studies before and during at-risk temporal windows for the disease.

Effects of bisphenol A on cardiovascular disease: An epidemiological study using National Health and Nutrition Examination Survey 2003-2016 and meta-analysis

As the most widely consumed endocrine-disrupting chemical, bisphenol A (BPA) has been linked to reproductive dysfunction, diabetes mellitus, and obesity. However, the evidence for an association between BPA and cardiovascular disease (CVD) remains insufficient. In the present study, we aimed to identify the association between BPA and CVD, using data from the 2003-2016 National Health and Nutrition Examination Surveys (NHANES). We estimated urine BPA concentration after adjustments for creatinine (ng/mg) and normalized the asymmetrical distribution using natural logarithmic transformation (ln-BPA/Cr). A multivariate logistic regression was performed to evaluate the odds ratio (OR) and 95% confidence interval (CI) for CVD, with ln-BPA/Cr concentration as predictor. We then performed a Mantel-Haenszel meta-analysis with five eligible studies and NHANES 2003-2016 data. Our subjects were 11,857 adults from the NHANES data. After adjusting for age, sex, race/ethnicity, body mass index (BMI), cigarette smoking, diabetes status, hypertension, and dyslipidemia, OR between ln-BPA/Cr and CVD was 1.13 (95% CI: 1.02-1.24). After propensity-score-matching with age, sex, race/ethnicity, BMI, cigarette smoking, diabetes, hypertension, and dyslipidemia, OR continued to be significant for the association between ln-BPA/Cr and CVD (OR: 1.18, 95% CI: 1.04-1.33). A restricted cubic spline plot of this relationship revealed a dose-dependent increase in OR. However, untransformed BPA had a linear relationship with CVD only at low concentrations, whereas the OR of BPA plateaued at high concentrations. In a meta-analysis with 22,878 subjects, after adjusting for age, sex, and various cardiometabolic risk factors, OR was 1.13 (95% CI, 1.03-1.23). In conclusion, our study provides additional epidemiological evidence supporting an association between BPA and CVD.

Bisphenol A and six other environmental phenols in urine of children and adolescents in Germany - human biomonitoring results of the German Environmental Survey 2014-2017 (GerES V)

Exposure to environmental phenols such as bisphenol A, benzophenones, 2-phenylphenol, triclosan, and triclocarban is of concern, because of their endocrine disrupting properties and broad application in consumer products. The current body burden of the 3-17-year-old population in Germany to these substances was assessed in first-morning void urine samples (N = 515-516) collected within the population-representative German Environmental Survey for Children and Adolescents 2014-2017 (GerES V). Bisphenol A was the most prominent phenol analysed here, ubiquitously found in almost all samples with a geometric mean (GM) concentration of 1.905 μg/L (1.669 μg/g_creatinine) and a maximum (MAX) urinary concentration of 399 μg/L. Benzophenone-3 and benzophenone-1 were quantified in 35% and 41% of the samples. GM was below the limit of quantification (LOQ) for benzophenone-3 and 0.559 μg/L (0.489 μg/g_crea) for benzophenone-1, MAX concentrations were 845 μg/L and 202 μg/L, respectively. In 16% of the samples triclosan was found in quantifiable amounts resulting in a GM below LOQ and a MAX concentration of 801 μg/L. Benzophenone-8, 2-phenylphenol and triclocarban were quantified in none or only 1% of the samples. Benzophenone-1 and -3 concentrations were found to be associated with frequent application of personal care products. A comparison with the previous cycle of the survey, GerES IV (2003-2006), showed a decrease of urinary bisphenol A concentrations, mainly in young children. Despite this decrease, the concentration of bisphenol A exceeded the human biomonitoring (HBM) value HBM-I of 0.1 mg/L in 0.11% of the samples. For triclosan, all urinary concentrations were well below the HBM-I value of 2 mg/L. To minimise environmental health risks, it is therefore necessary to maintain a further declining trend for bisphenol A and continue monitoring the exposure to environmental phenols, as well as to monitor substitutes such as bisphenol F and S.

Determinants of exposure levels of bisphenols in flemish adolescents

The broadly used industrial chemical bisphenol A (BPA), applied in numerous consumer products, has been under scrutiny in the past 20 years due to its widespread detection in humans and the environment and potential detrimental effects on human health. Following implemented restrictions and phase-out initiatives, BPA is replaced by alternative bisphenols, which have not received the same amount of research attention. As a part of the fourth cycle of the Flemish Environment and Health Study (FLEHS IV, 2016-2020), we monitored the internal exposure to six bisphenols in urine samples of 423 adolescents (14-15 years old) from Flanders, Belgium. All measured bisphenols were detected in the study population, with BPA and its alternatives bisphenol F (BPF) and bisphenol S (BPS) showing detection frequencies > 50%. The reference values show that exposure to these compounds is extensive. However, the urinary BPA level decreased significantly in Flemish adolescents compared to a previous cycle of the FLEHS (2008-2009). This suggests that the replacement of BPA with its analogues is ongoing. Concentrations of bisphenols measured in the Flemish adolescents were generally in the same order of magnitude compared to recent studies worldwide. Multiple regression models were used to identify determinants of exposure based on information on demographic and lifestyle characteristics of participants, acquired through questionnaires. Some significant determinants could be identified: sex, season, smoking behavior, educational level of the parents, recent consumption of certain foods and use of certain products were found to be significantly associated with levels of bisphenols. Preliminary risk assessment showed that none of the estimated daily intakes (EDIs) of BPA exceeded the tolerable daily intake, even in a high exposure scenario. For alternative bisphenols, no health-based guidance values are available, but in line with the measured urinary levels, their EDIs were lower than that of BPA. This study is, to the best of our knowledge, the first to determine internal exposure levels of other bisphenols than BPA in a European adolescent population.

Transcriptomic pathway and benchmark dose analysis of Bisphenol A, Bisphenol S, Bisphenol F, and 3,3',5,5'-Tetrabromobisphenol A in H9 human embryonic stem cells

Bisphenol A (BPA) is a chemical used in the manufacturing of plastics to which human exposure is ubiquitous. Numerous studies have linked BPA exposure to many adverse health outcomes prompting the replacement of BPA with various analogues including bisphenol-F (BPF) and bisphenol S (BPS). Other bisphenols are used in various consumer applications, such as 3,3',5,5'-Tetrabromobisphenol A (TBBPA), which is used as a flame retardant. Few studies to date have examined the effects of BPA and its analogues in stem cells to explore potential developmental impacts. Here we used transcriptomics to investigate similarities and differences of BPA and three of its analogues in the estrogen receptor negative, human embryonic stem cell line H9 (WA09). H9 cells were exposed to increasing concentrations of the bisphenols and analyzed using RNA-sequencing. Our data indicate that BPA, BPF, and BPS have similar potencies in inducing transcriptional changes and perturb many of the same pathways. TBBPA, the least structurally similar bisphenol of the group, exhibited much lower potency. All bisphenols robustly impacted gene expression in these cells, albeit at concentrations well above those observed in estrogen-positive cells. Overall, we provide a foundational data set against which to explore the transcriptional similarities of other bisphenols in embryonic stem cells, which may be used to assess the suitability of chemical grouping for read-across and for preliminary potency evaluation.

Associations among urinary triclosan and bisphenol A concentrations and serum sex steroid hormone measures in the Canadian and U.S. Populations

Exposure to triclosan, an antimicrobial agent, and bisphenol A (BPA), the monomer of polycarbonate plastics, is widespread. Endocrine-disrupting impacts of these chemicals have been demonstrated in in vitro studies, rodent toxicology studies, and some human observational studies. Here we compared urinary concentrations of triclosan and BPA in the Canadian and U.S. populations using nationally-representative data from the 2012-2015 Canadian Health Measures Survey (CHMS) and the 2013-2016 National Health and Nutrition Examination Survey (NHANES). We then examined the cross-sectional associations of urinary triclosan or BPA with serum sex steroid hormones, including estradiol (E2), progesterone (P4), and testosterone (T), using multivariable regression. We observed differences in creatinine-standardized chemical concentrations between countries; urinary triclosan was higher in Canadian females aged 12-19 years, while BPA was higher in U.S. females aged 20-49 years. We also found significant associations among urinary chemicals and serum E2 and T, but not P4. Increasing triclosan was associated with higher levels of E2 in 6-11-year-old girls, but with lower levels of E2 and T in adolescent boys aged 12-19 years. Increasing BPA was associated with lower levels of E2 in 6-11-year-old boys and in adolescents aged 12-19 years of either sex. We observed a U-shaped association between urinary triclosan and E2 in male adults aged 50-79 years; no associations between BPA and hormones were detected in adults. These results, in accordance with the in vitro and animal literature, suggest that triclosan and BPA exposures may be cross-sectionally associated with altered reproductive hormone levels, especially in children and adolescents. Further research and prospective studies are necessary to elucidate country-specific differences in chemical exposures and the potential public health significance of these findings.

Quantification of bisphenols in Korean urine using online solid-phase extraction-high-performance liquid chromatography-tandem mass spectrometry

Bisphenol A (BPA), an endocrine-disrupting chemical, has been used as a basic raw material for the production of polycarbonate plastics. As concern over the toxic effects of BPA grows, it is gradually being replaced in many consumer products with compounds such as bisphenol F (BPF) and bisphenol S (BPS). In this study, online solid-phase extraction-high-performance liquid chromatography-tandem mass spectrometry was used to analyze the urinary concentrations of BPA, BPF, and BPS in 2487 Korean urine samples collected between 2017 and 2018. The detection rates and geometric mean (GM) concentrations were as follows: BPA (82.1 %; 0.65 μg/L), BPF (11.1 %; not calculated), and BPS (63.6 %; 0.20 μg/L), respectively. The mean daily intake based on urinary BPA concentrations was 0.013 μg/kg bw/day (95th percentile, 0.089 μg/kg bw/day), which is lower than the tolerable daily intake. This is the first study observing urinary BPA, BPF, and BPS concentrations based on a nationally representative Korean population and could contribute to the evaluation of bisphenol analogue exposure levels in risk assessments.

Bisphenol A and its analogues: A comprehensive review to identify and prioritize effect biomarkers for human biomonitoring

Human biomonitoring (HBM) studies have demonstrated widespread and daily exposure to bisphenol A (BPA). Moreover, BPA structural analogues (e.g. BPS, BPF, BPAF), used as BPA replacements, are being increasingly detected in human biological matrices. BPA and some of its analogues are classified as endocrine disruptors suspected of contributing to adverse health outcomes such as altered reproduction and neurodevelopment, obesity, and metabolic disorders among other developmental and chronic impairments. One of the aims of the H2020 European Human Biomonitoring Initiative (HBM4EU) is the implementation of effect biomarkers at large scales in future HBM studies in a systematic and standardized way, in order to complement exposure data with mechanistically-based biomarkers of early adverse effects. This review aimed to identify and prioritize existing biomarkers of effect for BPA, as well as to provide relevant mechanistic and adverse outcome pathway (AOP) information in order to cover knowledge gaps and better interpret effect biomarker data. A comprehensive literature search was performed in PubMed to identify all the epidemiologic studies published in the last 10 years addressing the potential relationship between bisphenols exposure and alterations in biological parameters. A total of 5716 references were screened, out of which, 119 full-text articles were analyzed and tabulated in detail. This work provides first an overview of all epigenetics, gene transcription, oxidative stress, reproductive, glucocorticoid and thyroid hormones, metabolic and allergy/immune biomarkers previously studied. Then, promising effect biomarkers related to altered neurodevelopmental and reproductive outcomes including brain-derived neurotrophic factor (BDNF), kisspeptin (KiSS), and gene expression of nuclear receptors are prioritized, providing mechanistic insights based on in vitro, animal studies and AOP information. Finally, the potential of omics technologies for biomarker discovery and its implications for risk assessment are discussed. To the best of our knowledge, this is the first effort to comprehensively identify bisphenol-related biomarkers of effect for HBM purposes.

Urinary bisphenol A concentrations and adiposity measures at age 7 years in a prospective birth cohort

Bisphenol A (BPA) exposure during early life may increase risk of childhood obesity, however, prospective evidence of birth cohort is limited and inconclusive. We aimed to explore the associations of maternal and childhood BPA exposure with child adiposity measures, including body mass index, waist circumference and skinfold thickness and waist to height ratio of children at 7 years. 430 mother-child pairs were examined from a population-based prospective cohort in a rural area of East China. BPA concentrations of spot urine samples were quantified in mothers and their children aged 3 and 7 years. Maternal urinary BPA concentration was significantly positively associated with waist circumference in children aged 7 years (β = 0.508 cm, 95% CI: 0.067, 0.950). These significant associations were not modified by child sex, but they were only observed among girls in sex-stratified analyses. Risk of central obesity related to prenatal BPA exposure was significantly higher in the second and the third tertile than those in the first tertile (odds ratio, OR = 2.510, 95% CI = 1.146, 5.499; OR = 2.584, 95% CI = 1.186, 5.631, respectively; p for trend = 0.022). The present findings suggested that prenatal exposure to BPA may enhance waist circumference of children and thereby increase risk of central obesity in school-age girls.

The effects of maternal exposure to BPA during pregnancy on the male reproductive system and the testicular microRNA expression profile

The effect of prenatal bisphenol A (BPA) exposure is increasingly concerned. We investigated the effect of maternal BPA exposure during pregnancy on male offspring and its potential mechanism. Thirty pregnant Sprague Dawley (SD) rats were randomly divided into exposed and control groups. At PND56, the number of sperm, luteinizing hormone, and testosterone in the BPA-exposed group decreased, and testicular tissue structure was damaged in offsprings. At GD20, the miRNA profile in the testis of male offspring was examined and the expression levels of 28 deregulated miRNAs were validated by qRT-PCR. We found that miR-361-5p, miR-203a-3p, and miR-19b-2-5p had significantly different expression levels in the testis. These results suggest that maternal exposure to BPA can lead to differential changes in progeny miRNAs, which will provide direction for future in-depth mechanisms of reproductive injury.

Regional variations in human chemical exposures in Canada: A case study using biomonitoring data from the Canadian Health Measures Survey for the provinces of Quebec and Ontario

The Canadian Health Measures Survey (CHMS), an ongoing national health survey conducted in two-year cycles, collects extensive biomonitoring data that is used to assess the exposure of Canadians to environmental chemicals of concern. Combining data from multiple cycles of the CHMS allows for the calculation of robust regional estimates of chemical concentrations in blood and urine. The objective of this work was to compare biomarkers of exposure to several environmental chemicals for the provinces of Quebec and Ontario, two major CHMS regions, as well as the entire CHMS (representing Canada) minus Quebec (CMQ), and the entire CHMS minus Ontario (CMO), and to interpret differences between regions. Geometric means and 95th percentiles of blood and/or urinary concentrations of 45 environmental chemicals or their metabolites for Ontario, Quebec, CMQ, and CMO were calculated by combining the two most recent cycles of data available for a chemical (cycles 1 and 2, or cycles 2 and 3) from the first three cycles of the CHMS (2007-2013). Weighted one-way ANOVA was used to test the differences between regional estimates. After applying a Bonferonni-Holm adjustment for multiple comparisons, the following measures were significantly higher in Quebec as compared to Ontario and CMQ: blood lead, urinary lead and the urinary polyaromatic hydrocarbon (PAH) metabolites, 9-hydroxyfluorene, 1-hydroxyphenanthrene, 2- hydroxyphenanthrene and 3-hydroxyphenanthrene. In Quebec compared to CMQ only, urinary 2-hydroxfluorene, 3-hydroxyfluorene, 2-hydroxynaphthalene, and 4-hydroxyphenanthrene were higher. The concentration of urinary fluoride was significantly higher in Ontario as compared to Quebec and CMO. Blood manganese and urinary fluoride were significantly lower in Quebec compared to CMQ, and blood and urinary selenium were significantly lower in Ontario compared to CMO. Regional differences in tobacco use, age of dwellings and drinking water fluoridation are among the possible contributing factors to some of the observed differences. In conclusion, this is the first study where biomonitoring data from multiple cycles of CHMS were combined in order to generate robust estimates for subsets of the Canadian population. Such assessments can contribute to a regional-level prioritization of control measures to reduce the exposure of Canadians to chemicals in their environment.

Occurrence, fate and risk assessment of BPA and its substituents in wastewater treatment plant: A review

Several bisphenol analogues (BPs) are gradually replacing bisphenol A (BPA) in many fields, following strict restrictions on the production and use of BPA. The presence of micropollutants in wastewater treatment plants (WWTPs) may pose risks to the aquatic ecosystem and human health. In this review, we outlined the occurrence and fate of BPs in WWTPs, and estimated their potential risks to the aquatic ecosystem. BPA is still the most predominant bisphenol analogue in WWTPs with high detection rate and concentration, followed by bisphenol S (BPS) and F (BPF). Biodegradation and adsorption are the main removal pathways for removal of BPs in WWTPs. The secondary (activated sludge process, biological aerated filter, and membrane bioreactor) and advanced (membrane technique, ultraviolet disinfection, adsorption process, and ozonation) treatment processes show high removal efficiency for BPs, which are influenced by many factors such as sludge retention time and redox conditions. BPs other than BPA (assessed in this review) in effluent of WWTPs have low risks to Daphnia magna and early life stages on medaka, while BPA shows a medium or high risk under certain conditions. Knowledge gaps have been identified and future line of research on this class of chemicals in WWTPs is recommended. More data are needed to illustrate the occurrence and fate of BPs in WWTPs. Environmental risks of BPs other than BPA initiating from wastewater discharge to aquatic organisms remain largely unknown.

Quantification of eight bisphenol analogues in blood and urine samples of workers in a hazardous waste incinerator

Bisphenol A (BPA) has been widely used in the manufacture of polycarbonate plastic and epoxy resins. In recent years, producers have started replacing BPA by other chemical analogues, such as bisphenol -S (BPS) and -F (BPF), all of them under the label "BPA-free". However, despite bisphenol (BP) analogues have a very similar structure, their endocrine-disrupting properties could differ from those of BPA. Unfortunately, information regarding human exposure to BP analogues is very limited, not only as single substances, but also as chemical mixtures. The aim of this study was to determine the levels of 8 BP analogues (A, S, F, B, AF, Z, E, and AP) in biological samples from a controlled cohort of workers in a hazardous waste incinerator (HWI) located in Constantí (Catalonia, Spain). Firstly, a chemical method to analyze a mixture of those 8 analogues in total blood and urine was optimized, being samples quantified by means of gas chromatography coupled to mass spectrometry (GC-MS). Furthermore, a biomonitoring study was performed by collecting samples of total blood and urine of 29 people working in the HWI. Among the 8 BP analogues assessed, BPA presented the highest levels in both biological samples, with mean total (free + conjugated) BPA concentrations of 0.58 and 0.86 μg/L in blood and urine, respectively. Free vs. total BPA levels presented a mean percentage of 79% in blood and 19% in urine. Beyond BPA, traces of BPB were also found in a single sample of blood. Furthermore, none of the remaining BP analogues was detected in blood or urine. Despite BPA has been regulated, it is still very present in the environment, being human exposure to this chemical still an issue of concern for the public health.