Gender differences in the levels of bisphenol A metabolites in urine

Determination of urinary levels of Bisphenol A in a Turkish population

Bisphenol A (BPA) is one of the environmental endocrine disrupting chemicals that is widely used in common consumer products. The aim of this study was to report the total urinary BPA concentrations (free plus conjugated) in 200 urine samples (children: 57; male: 74; female: 69) obtained from residents of a Mediterranean city, Mersin. Analyses were performed by high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) and for assessing environmental exposure to free BPA and its major metabolite bisphenol A glucuronide (BPAG) in human urine were determinated. Our results indicated that the free BPA and BPAG concentrations were in the range of 0.06-0.99 μg/g creatinine and 0.24-615 μg/g creatinine, respectively. No statistically significant difference obtained in BPA concentrations between genders (male and female) or domicile of residence (rural and urban) (p > 0.05). In our study, the mean level of detected free BPA was 0.46 μg/g creatinine in the urban area and 0.37 μg/g creatinine in the rural area. The average amount of BPAG was 60.56 μg/g creatinine in the urban area and 30.28 μg/g creatinine in the rural area. The data demonstrate that determined amount of total BPA in the present study is lower than the results of similar studies conducted in developed countries. There is no data about the levels of BPA in humans and environment in Turkey. Because of this reason, present study is very important since it is the first study in Turkey which determined the concentrations of free BPA and total BPA in human.

Exposure to bisphenol A among school children in eastern China: a multicenter cross-sectional study

Bisphenol A (BPA) is one of the highest production and consumption volume chemicals in the world. Although exposure of children to BPA has been studied in Western countries, little is known about its level in China. In this study, total BPA was measured in the morning urine samples of 666 school children aged 9-12 years from three regions in eastern China in 2012. A rapid and sensitive ultraperformance liquid chromatography (UPLC) tandem mass spectrometry (MS/MS) method was used for the measurement and urinary concentrations of BPA were presented as unadjusted (ng/ml), creatinine-adjusted (μg/g creatinine) and specific gravity (SG)-adjusted (ng/ml) forms. BPA was detected in 98.9% of urine samples with their unadjusted concentrations ranging from 0.1 to 326.0 ng/ml (LOD=0.06 ng/ml), indicating that the exposure of BPA was common for school children living in eastern China. The geometric mean and median of BPA was 1.11 ng/ml (creatinine-adjusted: 2.32 μg/g creatinine; SG-adjusted: 1.17 ng/ml) and 1.00 ng/ml (creatinine-adjusted: 2.22 μg/g creatinine; SG-adjusted: 1.07 ng/ml), respectively. The highest urinary BPA level was found in the age group of 12 years with GM concentration of 1.55 ng/ml, and it decreased with decreasing age (11 years: 1.18 ng/ml; 10 years: 1.05 ng/ml; and 9 years: 0.99 ng/ml), but there was a lack of consistency for age associated with BPA levels in three study areas. The estimated daily intake of BPA (0.023 μg/kg bw/day) was much lower than the tolerable daily and reference dose of 50 μg/kg bw/day recommended by either the European Food Safety Authority or the US Environment Protection Agency. There was no significant difference in urinary BPA concentrations between children who were overweight or obese and those with normal weight (P=0.26), whereas BPA daily intake was unexpectedly higher among normal-weight children (P=0.003). Compared with creatinine correction, the correction method of specific gravity is preferred to evaluate BPA exposure for children.

Bisphenol A, 4-tert-octylphenol, and 4-nonylphenol in the Gulf of Gdańsk (Southern Baltic)

The organic derivatives of phenol are classed as dangerous compounds, and their presence has been detected in surface water, bottom water, phytoplankton, zooplankton, and mussel as well as liver and muscle of fish from the Gulf of Gdańsk and in liver, muscle, and guano of gulls residing in the coastal zone of this basin. The greatest sources of bisphenol A (BPA), 4-tert-octylphenol (OP), and 4-nonylphenol (NP) were found to be the Vistula River and the water purification plant in Dębogórze. In living organisms, concentrations of BPA, OP, and NP ranged between the limit of quantification and several hundred ng g(-1) dry weight (dw), and the highest concentrations were found for BPA. Prolonged alimentary exposure to BPA, OP, and NP in fish and birds was indicated by liver/muscle concentration ratios generally >1. The most influential factors on BPA and alkylphenol concentrations in the tissues of fishes and gulls were mainly diet and habitat. The study confirmed possible bioaccumulation in the food web. High BPA and NP concentrations in guano (≤2,700 and ≤300 ng g(-1) dw, respectively) indicated the ability of birds to detoxify and signalled the reintroduction of these compounds to seawater. Herring, flounder, and cod from the Southern Baltic are a safe food source for human consumption because their BPA and alkylphenol contents are low.

Human hepatic UGT2B15 developmental expression

Human hepatic UGT2B15 developmental expression changes may alter the metabolism of important drugs and toxicants such as bisphenol A (BPA). Previously, UGT2B15 ontogeny knowledge consisted of transcript data, a dubious surrogate for protein expression. Herein, UGT2B15 protein content was determined in human hepatic microsomes (n = 236, 8 weeks gestation to 18 years). The impact of a common, functional single nucleotide polymorphism (g.253G>T), present in UGT2B15*2 and *5 alleles, was also tested. UGT2B15 expression began during late fetal life, at about 18% of mature values (medians = 48, 267 pmoles/mg of microsomal protein, respectively; p < 0.001). UGT2B15 neonatal (n = 39) and late fetal (≥28 weeks, n = 10) content was similar, but lower than that of infants between 3 and 15 weeks age (n = 46; medians = 38, 48, 404 pmoles/mg microsomal protein, respectively; p < 0.001). Values for the latter group were higher compared with the remaining age group (15 weeks to 18 years; n = 82, p < 0.001). UGT2B15 expression varied 31-fold across the entire sample, and within groups, ranged from 4- to 27-fold. Among postnatal samples, age group, the presence of g.253T and male gender were each significantly associated with greater UGT2B15 expression (p < 0.001, <0.01, and <0.05, respectively; stepwise linear regression). In summary, hepatic UGT2B15 protein onset begins in late gestation; however, the greatest rate of change occurs during the first few weeks after birth. We speculate that the fetus and neonate may have lower clearance of some UGT2B15 substrates, such as BPA, compared with older individuals.

Quantitative determination of free and total bisphenol A in human urine using labeled BPA glucuronide and isotope dilution mass spectrometry

Bisphenol A (BPA) is a widely used industrial chemical in the manufacturing of polycarbonate plastic bottles, food and beverage can linings, thermal receipts, and dental sealants. Animal and human studies suggest that BPA may disrupt normal hormonal function and hence, potentially, have negative effects on the human health. While total BPA is frequently reported, it is recognized that free BPA is the biologically active form and is rarely reported in the literature. The objective of this study was to develop a sensitive and improved method for the measurement of free and total BPA in human urine. Use of a labeled conjugated BPA (bisphenol A-d6 β-D-glucuronide) allowed for the optimization of the enzymatic reaction and permitted an accurate determination of the conjugated BPA concentration in urine samples. In addition, a (13)C12-BPA internal standard was used to account for the analytical recoveries and performance of the isotope dilution method. Solid-phase extraction (SPE) combined with derivatization and analysis using a triple quadrupole GC-EI/MS/MS system achieved very low method detection limit of 0.027 ng/mL. BPA concentrations were measured in urine samples collected during the second and third trimesters of pregnancy in 36 Canadian women. Total maternal BPA concentrations in urine samples ranged from not detected to 9.40 ng/mL (median, 1.21 ng/mL), and free BPA concentrations ranged from not detected to 0.950 ng/mL (median, 0.185 ng/mL). Eighty-six percent of the women had detectable levels of conjugated BPA, whereas only 22 % had detectable levels of free BPA in their urine. BPA levels measured in this study agreed well with data reported internationally.

Bisphenol A (BPA) and its potential role in the pathogenesis of the polycystic ovary syndrome (PCOS)

Polycystic ovary syndrome (PCOS) is the most common and the most heterogeneous endocrine disorder in premenopausal women. Apart from signs of hyperandrogenism such as acne, hirsutism and hair loss, women with PCOS usually present with menstrual irregularities and fertility problems.Additionally, they are often characterized by impaired glucose tolerance, which usually leads to the development of type 2 diabetes mellitus (T2DM). This review article describes current and novel approach to the pathomechanisms of PCOS and the potential role of an endocrine disrupting chemical ("endocrine disruptor" - ED) - bisphenol A (BPA), which is commonly used as a plasticizer and due to its molecular structure can interact with estrogen receptors (ERs). Recent observations point to the higher levels of BPA in biological fluids of women with PCOS and its role in the pathogenesis of hyperandrogenism and hyperinsulinemia. It seems that mother's exposure to BPA during pregnancy may also lead to the development of PCOS in the female offspring.

Simultaneous determination of some phthalate metabolites, parabens and benzophenone-3 in urine by ultra high pressure liquid chromatography tandem mass spectrometry

Phthalates, parabens and 2-hydroxy-4-methoxybenzophenone or benzophone-3 are thought to act as endocrine disrupting chemicals, being able to disrupt the endocrine balance and therefore able to lead to some hormonal diseases. Numerous large-scale biomonitoring studies have detected the biomarkers of these compounds in more than 75% of the general population. To assess the exposure to these chemicals, we developed an analytical method based on a Solid Phase Extraction (SPE) prior to ultra high pressure liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) for the simultaneous measurement of seven phthalate metabolites (monobenzyl phthalate, mono-n-butyl phthalate, mono-iso-butyl phthalate, mono-2-ethylhexyl phthalate, mono-2-ethyl-5-hydroxyhexyl phthalate, mono-2-ethyl-5-oxohexyl phthalate, monoethyl phthalate), four parabens (methyl paraben, ethyl paraben, n-propyl paraben, n-butyl parabens) and benzophenone-3 in human urine. The distinction between unconjugated, glucuro- and sulfoconjugated forms was achieved using different enzymatic hydrolyses. The whole procedure was validated according to the total error approach, and was demonstrated to be linear (regression coefficient ranging from 0.987 to 0.998) and accurate (inter and intra assay precision <17.71%, relative bias <5.87%) in the dosing range of concentrations. The limits of quantification (LOQs) obtained ranged between 0.30 and 1.23ng/ml depending on the analyte. The reliability of the method was proven in passing successfully the German External Quality Assessment Scheme (G-EQUAS). Moreover, the urine from 25 volunteers were analyzed for the determination of glucuro-, sulfo- and free species separately. Phthalate metabolites, parabens and benzophenone-3 were positively detected in almost all urine samples, with detection rates ranging from 40 to 100%. Levels measured ranged from <LOQ to 2207ng/ml varying widely depending on the compound and the individual. In our small participating population, most of the phthalate metabolites were excreted predominately as glucuroconjugated forms while parabens and benzophenone-3 were detected as glucuro- and sulfoconjugated species in variable proportions according to the target compound.

Urine bisphenol-A level in relation to obesity and overweight in school-age children

Bisphenol-A (BPA) is a potential endocrine disruptor impacting metabolic processes and increasing the risk of obesity. To determine whether urine BPA level is associated with overweight/obesity in school-age children, we examined 1,326 students in grades 4–12 from three schools (one elementary, one middle, and one high school) in Shanghai. More than 98% of eligible students participated. Total urine BPA concentration was measured and anthropometric measures were taken by trained research staff. Information on risk factors for childhood obesity was collected for potential confounders. Age- and gender-specific weight greater than 90^th percentile of the underlying population was the outcome measure. After adjustment for potential confounders, a higher urine BPA level (≥2 µg/L), at the level corresponding to the median urine BPA level in the U.S. population, was associated with more than two-fold increased risk of having weight >90^th percentile among girls aged 9–12 (adjusted odds ratio (aOR) = 2.32, 95% confidence interval: 1.15–4.65). The association showed a dose-response relationship with increasing urine BPA level associated with further increased risk of overweight (p = 0.006 for trend test). Other anthropometric measures of obesity showed similar results. The same association was not observed among boys. This gender difference of BPA effect was consistent with findings from experimental studies and previous epidemiological studies. Our study suggests that BPA could be a potential new environmental obesogen. Widespread exposure to BPA in the human population may also be contributing to the worldwide obesity epidemic.

Association between water consumption from polycarbonate containers and bisphenol A intake during harsh environmental conditions in summer

With the exception of polycarbonate (PC) baby bottles, little attention has been paid to bisphenol A (BPA) intake from packaged water consumption (PC water dispensers), especially during summer weather conditions. We determined the magnitude and variability of urinary BPA concentrations during summer in 35 healthy individuals largely relying upon PC packaged water to satisfy their potable needs. We used liquid chromatography-tandem mass spectrometry to measure urinary BPA concentrations. A questionnaire was administered in July/August and a spot urine sample was collected on the same day and 7 days after the completion of the interview (without intervention). Linear regression was performed to assess the association of variables, such as water consumption from different sources, on urinary BPA levels for the average of the two urine samples. A significant positive association (p = 0.017) was observed between PC water consumption and urinary BPA levels in females, even after adjusting for covariates in a multivariate regression model. The geometric mean of daily BPA intake back-calculated from urinary BPA data was 118 ng · (kg bw)(-1) · day(-1), nearly double the average intake levels observed in biomonitoring studies worldwide. High urinary BPA levels were partially ascribed to summer's high PC water consumption and weather characteristics (high temperatures, >40 °C; very high UV index values, >8), which could be causing BPA leaching from PC. It is suggested that PC-based water consumption could serve as a proxy for urinary BPA, although the magnitude of its relative contribution to overall daily intake requires further investigation.

4-Nonylphenol, bisphenol-A and triclosan levels in human urine of children and students in China, and the effects of drinking these bottled materials on the levels

4-Nonylphenol (4-NP), bisphenol-A (BPA) and triclosan (TCS) are three industrial chemicals used widely in daily products. This study investigated 4-NP, BPA and TCS levels in urine samples of 287 children and students aged from 3 to 24 years old in Guangzhou, China. Total (free and conjugated) amounts of 4-NP, BPA and TCS in the urine samples were detected using gas chromatography-mass spectrometry with negative chemical ionization. The detection rates of 4-NP, BPA and TCS were 100%, 100% and 93% respectively, given the detection limits of 3.8, 0.5 and 0.9 ng/L respectively. Data for 4-NP, BPA and TCS were presented in both creatinine-adjusted (microgram per gram creatinine) and unadjusted (microgram per liter) urinary concentrations. The geometric mean (GM) concentrations of urinary 4-NP, BPA and TCS were 15.92 μg/g creatinine (17.40 μg/L), 2.75 μg/g creatinine (3.00 μg/L) and 3.55 μg/g creatinine (3.77 μg/L) respectively. Multiple regression models considering age, gender, preferred drinking bottle and log-transformed creatinine were used to calculate the adjusted least square geometric mean (LSGM). Among these subjects, the females had higher LSGM concentrations of 4-NP, BPA and TCS than the males; and the only statistically significant difference was found for the LSGM concentrations of triclosan (p=0.031). Participants who reported to use ceramic cups more frequently had significantly lower LSGM concentrations of BPA than those who used plastic cups (p=0.037). Meanwhile, a three-week test of using polycarbonate bottles and ceramic cups to drink bottled water and boiled tap-water was carried out among 12 graduate students of 25 years old. The GM concentrations of urinary BPA at the end of the first week after using ceramic cups to drink bottled water were 7.16 μg/g creatinine, then decreased significantly to 3.49 μg/g creatinine after the second week of using ceramic cups to drink boiled tap-water (p<0.05), and finally increased to 4.15 μg/g creatinine after the third week of using polycarbonate bottles in drinking boiled tap-water. The results indicate that in daily life the use of polycarbonate bottles or drinking of bottled water is likely to increase the ingestion of BPA, resulting in an increase in urinary BPA levels.

Age-related trends in urinary excretion of bisphenol A in Australian children and adults: evidence from a pooled sample study using samples of convenience

Bisphenol A (BPA or 4,4'-(propane-2,2-diyl)diphenol) is a chemical intermediate in the production of polycarbonate and epoxy resins, and is used in a wide range of applications. BPA has attracted significant attention in the past decade due to its frequency of detection in human populations worldwide, and has demonstrated animal toxicity and potential impact on human health, particularly during critical periods of development. The aim of this study was to perform a preliminary assessment of age-related trends in urinary concentration and to estimate daily excretion of BPA in Australian children (aged >0 to <5 yr) and adults (≥15 to <75 yr). This was achieved using 79 samples pooled by age and gender, created from 868 individual samples of convenience collected as part of routine, community-based pathology testing. Total BPA was analyzed using online solid phase extraction (SPE)-liquid chromatography tandem mass spectrometry (LC-MS/MS) and detected in all samples with a range of 0.65-265 ng/ml. No significant differences were observed between males and females. A urine flow model was constructed from published values and was used to provide an estimate of daily excretion per unit body weight for each pooled sample. The daily excretion estimates ranged from 26.2 to 18,200 ng/kg-d for children, and from 20.1 to 165 ng/kg-d for adults. Urinary concentrations and estimated excretion rates were inversely associated with age, and estimated daily excretion in infants and young children was significantly higher than in adults (geometric mean: 107 and 47.0 ng/kg-d, respectively). Higher excretion of BPA in children may be explained by their higher food consumption relative to body weight compared to adults and adolescents, and may also reflect alternative exposure pathways and sources.

Bisphenol A in 24 h urine and plasma samples of the German Environmental Specimen Bank from 1995 to 2009: a retrospective exposure evaluation

Human exposure to Bisphenol A (BPA) is omnipresent. Both the extent of the exposure and its toxicological relevance are controversially discussed. We aim to reliably determine and evaluate the extent of BPA body burden in the German population from 1995 to 2009 based on 600 24 h urine samples and corresponding plasma samples from the Environmental Specimen Bank. We determined total and unconjugated BPA in urine and plasma using on-line solid-phase extraction high-performance liquid chromatography coupled to isotope dilution tandem mass spectrometry with a limit of quantification (LOQ) of 0.1 μg/l. In the stored urines, total BPA was quantifiable in >96% (median: 1.49 μg/l; 95th percentile: 7.37 μg/l), whereas unconjugated BPA was quantifiable only in <15% of the samples. Total BPA concentrations decreased over time, but 24 h urine volumes increased. Therefore, daily intakes calculated from the 24 h urines remained rather constant at a median of 0.037 and a 95th percentile of 0.171 μg BPA/kg body weight/day. In 60 corresponding plasma samples, total BPA levels were generally below the LOQ of 0.1 μg/l and, if quantifiable, most BPA was unconjugated, thus hinting to external contamination. We see total BPA in urine as the most appropriate and robust marker for BPA exposure assessment (if controlled for BPA contamination). Unconjugated BPA in urine and unconjugated or total BPA in plasma where contamination or breakdown of the glucuronide cannot be ruled out are of no value for human exposure assessment.

Urinary bisphenol-A concentration in infertile Japanese women and its association with endometriosis: A cross-sectional study

OBJECTIVES

Bisphenol A (BPA), a raw material commonly used in the manufacture of resins such as polycarbonate and epoxy, is a possible xenoestrogen that is hypothesized to disrupt the human endocrine system. Humans are widely exposed to BPA. We investigated the urinary concentration of BPA in infertile Japanese women and its possible association with endometriosis.

MATERIALS AND METHODS

We recruited 166 women (aged 20-45) who had complained of infertility and visited a university hospital in Tokyo. The subjects were interviewed and their urine samples were obtained prior to a laparoscopic diagnosis of endometriosis between January 2000 and December 2001. Urinary total BPA concentration in 140 eligible urine samples was then measured using enzymatic deconjugation of glucuronide and sulfate and high-performance liquid chromatography isotope-dilution tandem mass spectrometry.

RESULTS

Median (25th-75th percentile) unadjusted and creatinine-adjusted urinary BPA concentrations were 1.6 (0.69-2.8) μg/L and 0.80 (0.45-1.3) μg/g creatinine. No significant monotonic association of endometriosis with urinary BPA concentration was observed. Median urinary BPA concentration in women with stage 0-1 endometriosis (0.74 μg/g creatinine) did not significantly differ from that in those with stage II-IV endometriosis (0.93 μg/g creatinine) (p for difference=0.24).

CONCLUSIONS

This study, based on a larger number of samples than those in previous studies in Japan and using the most reliable analytical method currently available, showed that urinary concentrations of BPA in women who consulted a physician for infertility were not higher than those in other populations. Moreover, no association between urinary BPA concentration and endometriosis was found in this cross-sectional study.

Determination of free and conjugated forms of bisphenol A in human urine and serum by liquid chromatography-tandem mass spectrometry

Exposure of humans to bisphenol A (BPA), a widely used industrial chemical, is well-known. In humans and animals, conjugation of BPA molecule with glucuronide or sulfate is considered as a mechanism for detoxification. Nevertheless, very few studies have directly measured free, conjugated (e.g., glucuronidated), and substituted (e.g., chlorinated) forms of BPA in human specimens. In this study, free, conjugated (BPA glucuronide or BPAG and BPA disulfate or BPADS), and substituted (chlorinated BPA; mono- [BPAMC], di-[BPADC], and trichloride [BPATrC]) forms of BPA were determined in human urine and serum samples, using solid-phase extraction (SPE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) techniques. The instrumental calibration for each of the target compounds ranged from 0.01 to 100 ng/mL and showed excellent linearity (r > 0.99). The limits of quantification (LOQs) were 0.01 ng/mL for free BPA and 0.05 ng/mL for the conjugated and substituted BPA. Respective recoveries of the six target compounds spiked into water blanks and sample matrices (urine and serum), and passed through the entire analytical procedure, were 96 ± 14% and 105 ± 18% (mean ± SD) for urine samples and 87 ± 8% and 80 ± 13% for serum samples. The optimal recoveries of BPAG and BPADS in the analytical procedure indicted that no deconjugation occurred during the SPE procedure. The method was applied to measure six target chemicals in urine and serum samples collected from volunteers in Albany, New York. BPA and its derivatives were found in urine samples at concentrations ranging from < LOQ to a few tens of ng/mL. In serum, free and conjugated BPA were detected at sub ng/mL concentrations, whereas BPA chlorides were not detected. The urine and serum samples were also analyzed by enzymatic deconjugation and liquid-liquid extraction (LLE) for the determination of total BPA, and the results were compared with those measured by the SPE method. To our knowledge, this is the first report on the occurrence of BPAG and BPADS in human serum.

Fetal bisphenol A exposure: concentration of conjugated and unconjugated bisphenol A in amniotic fluid in the second and third trimesters

Bisphenol A (BPA) is an estrogenic compound widely used in polycarbonate plastics. The placental enzyme β-glucuronidase may deconjugate BPA into its "free" active form. We sought to quantify levels of conjugated and free BPA in second and third trimester amniotic fluid. Liquid chromatography coupled with mass spectrometry was used to measure BPA concentrations in 20 second trimester and 20 third trimester amniotic fluid specimens. Total BPA was detected in 16/20 second trimester samples; levels ranged from non-detectable to 0.75ng/mL (median 0.47ng/mL). Free BPA was detected in 9/20 second trimester samples; levels ranged from 0.31 to 0.43ng/mL (median 0.38ng/mL). Total BPA was detected in 2/20 third trimester samples. Free BPA was detected in 1/20 (0.42ng/mL). When detected, free BPA comprised 83% and 91% of total BPA in second and third trimester amniotic fluid, respectively. Placental β-glucuronidase may deconjugate BPA, increasing fetal exposure to free BPA.

Urinary, Circulating, and Tissue Biomonitoring Studies Indicate Widespread Exposure to Bisphenol A

Bisphenol A (BPA) is one of the highest-volume chemicals produced worldwide, and human exposure to BPA is thought to be ubiquitous. Thus, there are concerns that the amount of BPA to which humans are exposed may cause adverse health effects. We examined many possibilities for why biomonitoring and toxicokinetic studies could come to seemingly conflicting conclusions. More than 80 published human biomonitoring studies that measured BPA concentrations in human tissues, urine, blood, and other fluids, along with two toxicokinetic studies of human BPA metabolism were examined. Unconjugated BPA was routinely detected in blood (in the nanograms per milliliter range), and conjugated BPA was routinely detected in the vast majority of urine samples (also in the nanograms per milliliter range). In stark contrast, toxicokinetic studies proposed that humans are not internally exposed to BPA. Available data from biomonitoring studies clearly indicate that the general population is exposed to BPA and is at risk from internal exposure to unconjugated BPA. The two toxicokinetic studies that suggested human BPA exposure is negligible have significant deficiencies, are directly contradicted by hypothesis-driven studies, and are therefore not reliable for risk assessment purposes.

Circulating levels of bisphenol A (BPA) and phthalates in an elderly population in Sweden, based on the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS)

The plastic manufacture compounds, bisphenol A (BPA) and phthalates, are ubiquitous and have therefore been detected in virtually all types of analyzed human samples. The aim of this study was: (1) to investigate concentrations of serum levels of BPA and phthalate metabolites in seniors residing in the city of Uppsala, Sweden (2) to evaluate gender differences in relation to serum levels of BPA and phthalate metabolites in the subjects. In the population-based Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS), encompassing 1016 subjects, all aged 70, serum levels of BPA and phthalate metabolites were measured by Isotope Dilution-High Performance Liquid Chromatography-Tandem Mass Spectrometry. BPA and four out of ten phthalate metabolites, namely, Monoisobutyl phthalate (MiBP), Monomethyl phthalate (MMP), Monoethyl phthalate (MEP), Mono-(2-ethylhexyl) phthalate (MEHP), were detectable in almost all subjects. Of the remaining phthalate metabolites, Monobenzyl phthalate (MBzP), Mono-(2-ethyl-5-hydroxyhexyl) phthalate (MeHHP), and Mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP) were seen in some 300-700 of the subjects, whereas Monoisononyl phthalate (MINP) and Mono-n-octyl phthalate (MOP) were found in only a few and Monocyclohexyl phthalate (MCHP) was not detected in any subject. Neither the circulation levels of BPA nor those of phthalate metabolites differ between the genders in this elderly population of residents in Uppsala, Sweden.

Urinary concentrations of bisphenol A and triclosan and associations with demographic factors in the Korean population

Bisphenol A (BPA) and triclosan are synthetic phenolic compounds to which the general public can be extensively exposed via consumer products and environmental contamination. In this study, we assessed exposure to BPA and triclosan in the Korean adult population aged 18-69 based on the Korean National Human Biomonitoring Survey conducted in 2009. Relying on data from 1870 representative Koreans, we found that the geometric mean urinary concentrations of BPA and triclosan were 1.90 ng/ml [95% confidence interval (CI): 1.81-1.99] and 1.68 ng/ml (95% CI: 1.48-1.90), respectively. The creatinine-adjusted geometric means of BPA and triclosan were 1.79 μg/g creatinine (95% CI: 1.70-1.90) and 1.58 μg/g creatinine (95% CI: 1.39-1.81), respectively. About 99.8% of the Korean adult population had urinary concentrations of BPA and about 92.6% of the Korean adult population had urinary concentrations of triclosan above the level of 0.05 ng/ml (limit of detection, LOD). Urinary BPA concentrations were higher in residents of rural areas, whereas urinary triclosan concentrations were significantly associated with cigarette smoking. These findings suggested that most Koreans had detectable levels of BPA and triclosan in their urine and that the body burden of BPA and triclosan varied according to demographic and geographic factors.

High levels of bisphenol A in paper currencies from several countries, and implications for dermal exposure

The sources of human exposure to bisphenol A (BPA) are not well characterized. Little is known about the presence of BPA in paper products, especially in paper currencies, and its implications for human exposure. In this work, paper currencies from 21 countries (N = 156) were analyzed for BPA, which was measured in 19 mm punches taken from three spots on the paper currencies. BPA was found in all paper currencies at concentrations ranging from 0.001 to 82.7 μg/g (mean 4.94; median 1.02) and the concentrations in samples taken from the middle portion of the currencies were higher than those taken from peripheral portions. We also examined the transfer of BPA from thermal receipt paper to currencies by placing currencies in contact with thermal receipt papers for 24 h in a wallet. Concentrations of BPA dramatically increased after 24 h of contact with thermal receipt papers, suggesting that thermal receipt paper is an important source of BPA in paper currencies. The estimated daily intake of BPA through dermal absorption from handling paper currencies was on the order of a few nanograms per day.

Bisphenol A exposure reduces the estradiol response to gonadotropin stimulation during in vitro fertilization

OBJECTIVE

To investigate associations between serum bisphenol A (BPA) concentrations and follicular response to exogenous ovary stimulation.

DESIGN

Fasting serum was prospectively collected on the day of oocyte retrieval and assessed for unconjugated BPA using high-performance liquid chromatography with Coularray detection. Multivariable linear regression and negative binomial regression were used to assess associations between concentrations of BPA and outcome measures. Models were adjusted for race/ethnicity, antral follicle count at baseline, and cigarette smoking.

SETTING

A reproductive health center.

PATIENT(S)

Forty-four women undergoing IVF.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Peak E(2) level and the number of oocytes retrieved during IVF.

RESULT(S)

The median unconjugated serum BPA concentration is 2.53 ng/mL (range = 0.3-67.36 ng/mL). Bisphenol A is inversely associated with E(2) (β = -0.16; 95% confidence interval = -0.32, 0.01), as well as with E(2) normalized to the number of mature-sized follicles at the hCG trigger (β = -0.14; 95% confidence interval = -0.24, -0.03). No association is observed for BPA and the number of oocytes retrieved (adjusted risk ratio = 0.95; 95% confidence interval = 0.82, 1.10).

CONCLUSION(S)

Bisphenol A is associated with a reduced E(2) response during IVF. Although limited by the preliminary nature of this study, these results merit confirmation in a future comprehensive investigation.

Critical evaluation of key evidence on the human health hazards of exposure to bisphenol A

Despite the fact that more than 5000 safety-related studies have been published on bisphenol A (BPA), there seems to be no resolution of the apparently deadlocked controversy as to whether exposure of the general population to BPA causes adverse effects due to its estrogenicity. Therefore, the Advisory Committee of the German Society of Toxicology reviewed the background and cutting-edge topics of this BPA controversy. The current tolerable daily intake value (TDI) of 0.05 mg/kg body weight [bw]/day, derived by the European Food Safety Authority (EFSA), is mainly based on body weight changes in two- and three-generation studies in mice and rats. Recently, these studies and the derivation of the TDI have been criticized. After having carefully considered all arguments, the Committee had to conclude that the criticism was scientifically not justified; moreover, recently published additional data further support the reliability of the two- and three-generation studies demonstrating a lack of estrogen-dependent effects at and below doses on which the current TDI is based. A frequently discussed topic is whether doses below 5 mg/kg bw/day may cause adverse health effects in laboratory animals. Meanwhile, it has become clear that positive results from some explorative studies have not been confirmed in subsequent studies with higher numbers of animals or a priori defined hypotheses. Particularly relevant are some recent studies with negative outcomes that addressed effects of BPA on the brain, behavior, and the prostate in rodents for extrapolation to the human situation. The Committee came to the conclusion that rodent data can well be used as a basis for human risk evaluation. Currently published conjectures that rats are insensitive to estrogens compared to humans can be refuted. Data from toxicokinetics studies show that the half-life of BPA in adult human subjects is less than 2 hours and BPA is completely recovered in urine as BPA-conjugates. Tissue deconjugation of BPA-glucuronide and -sulfate may occur. Because of the extremely low quantities, it is only of minor relevance for BPA toxicity. Biomonitoring studies have been used to estimate human BPA exposure and show that the daily intake of BPA is far below the TDI for the general population. Further topics addressed in this article include reasons why some studies on BPA are not reproducible; the relevance of oral versus non-oral exposure routes; the degree to which newborns are at higher systemic BPA exposure; increased BPA exposure by infusions in intensive care units; mechanisms of action other than estrogen receptor activation; and the current regulatory status in Europe, as well as in the USA, Canada, Japan, New Zealand, and Australia. Overall, the Committee concluded that the current TDI for BPA is adequately justified and that the available evidence indicates that BPA exposure represents no noteworthy risk to the health of the human population, including newborns and babies.

Determination of free and total bisphenol A in urine of infants

Infants may be particularly sensitive regarding hormonally active compounds such as Bisphenol A (BPA), which is widely distributed and exhibits weak oestrogenic activity. Since only free (unconjugated) BPA exhibits endocrine activity, both free and total (after hydrolysis of conjugates) BPA were determined in urine samples of infants to support valid risk assessments. Free BPA was observed above the LOQ in only 3 of 91 (3%) samples from 47 infants. As total BPA was observed in only 38 (42%) urine samples, with concentrations between <LOQ and 17.85 μg/l, the median concentration was below the LOQ of 0.45 μg/l. Based on 0.225 μg/l (half of the LOQ), a margin of exposure 1400-fold below the tolerable daily intake (TDI) of 50 μg/kg bw was calculated. The highest concentration observed (17.85 μg/l) was 18-fold below the TDI. Infants who were fed using baby bottles show approximately 2-fold higher median levels of total BPA. Importantly, the higher levels of total BPA compared to free BPA demonstrate that conversion of BPA to biologically inactive conjugates such as glucuronides or sulphates, which is well known to efficiently occur in adults, also occurs in infants.

Urinary, circulating, and tissue biomonitoring studies indicate widespread exposure to bisphenol A

BACKGROUND

Bisphenol A (BPA) is one of the highest-volume chemicals produced worldwide, and human exposure to BPA is thought to be ubiquitous. Thus, there are concerns that the amount of BPA to which humans are exposed may cause adverse health effects. Importantly, results from a large number of biomonitoring studies are at odds with the results from two toxicokinetic studies.

OBJECTIVE

We examined several possibilities for why biomonitoring and toxicokinetic studies could come to seemingly conflicting conclusions.

DATA SOURCES

We examined > 80 published human biomonitoring studies that measured BPA concentrations in human tissues, urine, blood, and other fluids, along with two toxicokinetic studies of human BPA metabolism.

DATA EXTRACTION AND SYNTHESIS

The > 80 biomonitoring studies examined included measurements in thousands of individuals from several different countries, and these studies overwhelmingly detected BPA in individual adults, adolescents, and children. Unconjugated BPA was routinely detected in blood (in the nanograms per milliliter range), and conjugated BPA was routinely detected in the vast majority of urine samples (also in the nanograms per milliliter range). In stark contrast, toxicokinetic studies proposed that humans are not internally exposed to BPA. Some regulatory agencies have relied solely on these toxicokinetic models in their risk assessments.

CONCLUSIONS

Available data from biomonitoring studies clearly indicate that the general population is exposed to BPA and is at risk from internal exposure to unconjugated BPA. The two toxicokinetic studies that suggested human BPA exposure is negligible have significant deficiencies, are directly contradicted by hypothesis-driven studies, and are therefore not reliable for risk assessment purposes.

Biomonitoring studies should be used by regulatory agencies to assess human exposure levels and safety of bisphenol A

BACKGROUND

Within the past 3 years, four major evaluations of bisphenol A (BPA) safety have been undertaken. However, these assessments have arrived at quite different conclusions regarding the safety of BPA at current human exposure levels.

OBJECTIVES

We compared the reasons provided by the European Food Safety Authority (EFSA) BPA risk assessment panel for their conclusion that human exposures are negligible with the conclusions reached by the other panels, with all panels having the same body of literature at their disposal.

DISCUSSION

The EFSA panel dismissed > or = 80 biomonitoring studies that documented significant levels of BPA exposure in humans, including internal exposures to unconjugated BPA, on the basis that they did not match a model of BPA metabolism. Instead, the EFSA panel relied on two toxicokinetic studies-conducted in 15 adults administered BPA-to draw conclusions about exposure levels in the population, including exposures of neonates.

CONCLUSIONS

As with all exposure assessments, models should be developed to explain actual data that are collected. In the case of BPA, samples from a large number of human subjects clearly indicate that humans are internally exposed to unconjugated BPA. The dismissal of these biomonitoring studies simply because their results do not conform to a model violates scientific principles. Expert panels should evaluate all data-including human biomonitoring studies-to make informed risk assessments.

Maternal bisphenol a exposure promotes the development of experimental asthma in mouse pups

BACKGROUND

We recently reported that various environmental estrogens induce mast cell degranulation and enhance IgE-mediated release of allergic mediators in vitro.

OBJECTIVES

We hypothesized that environmental estrogens would enhance allergic sensitization as well as bronchial inflammation and responsiveness. To test this hypothesis, we exposed fetal and neonatal mice to the common environmental estrogen bisphenol A (BPA) via maternal loading and assessed the pups' response to allergic sensitization and bronchial challenge.

METHODS

Female BALB/c mice received 10 microg/mL BPA in their drinking water from 1 week before impregnation to the end of the study. Neonatal mice were given a single 5 microg intraperitoneal dose of ovalbumin (OVA) with aluminum hydroxide on postnatal day 4 and 3% OVA by nebulization for 10 min on days 13, 14, and 15. Forty-eight hours after the last nebulization, we assessed serum IgE antibodies to OVA by enzyme-linked immunosorbent assay (ELISA) and airway inflammation and hyperresponsiveness by enumerating eosinophils in bronchoalveolar lavage fluid, whole-body barometric plethysmography, and a forced oscillation technique.

RESULTS

Neonates from BPA-exposed mothers responded to this "suboptimal" sensitization with higher serum IgE anti-OVA concentrations compared with those from unexposed mothers (p < 0.05), and eosinophilic inflammation in their airways was significantly greater. Airway responsiveness of the OVA-sensitized neonates from BPA-treated mothers was enhanced compared with those from unexposed mothers (p < 0.05).

CONCLUSIONS

Perinatal exposure to BPA enhances allergic sensitization and bronchial inflammation and responsiveness in a susceptible animal model of asthma.

Developmental pharmacogenetics: a general paradigm for application to neonatal pharmacology and toxicology

Therapy in newborn infants presents unique challenges. The consequences of exposure of the fetus to medications and environmental contaminants in utero (following the mother's exposure to these) may present, in the newborn, as congenital malformations or adverse drug reactions or have unknown long-term consequences. Risk is not uniformly distributed across a population. Rather, pharmacogenomic principles assert that an individual's unique clinical, genomic, and environmental information can be used to accurately predict predisposition to risk. The challenge is to identify the specific factors--genetic and nongenetic--that contribute to increased risk.

Polycarbonate bottle use and urinary bisphenol A concentrations

BACKGROUND

Bisphenol A (BPA) is a high-production-volume chemical commonly used in the manufacture of polycarbonate plastic. Low-level concentrations of BPA in animals and possibly in humans may cause endocrine disruption. Whether ingestion of food or beverages from polycarbonate containers increases BPA concentrations in humans has not been studied.

OBJECTIVES

We examined the association between use of polycarbonate beverage containers and urinary BPA concentrations in humans.

METHODS

We conducted a nonrandomized intervention of 77 Harvard College students to compare urinary BPA concentrations collected after a washout phase of 1 week to those taken after an intervention week during which most cold beverages were consumed from polycarbonate drinking bottles. Paired t-tests were used to assess the difference in urinary BPA concentrations before and after polycarbonate bottle use.

RESULTS

The geometric mean urinary BPA concentration at the end of the washout phase was 1.2 microg/g creatinine, increasing to 2.0 microg/g creatinine after 1 week of polycarbonate bottle use. Urinary BPA concentrations increased by 69% after use of polycarbonate bottles (p < 0.0001). The association was stronger among participants who reported > or = 90% compliance (77% increase; p < 0.0001) than among those reporting < 90% compliance (55% increase; p = 0.03), but this difference was not statistically significant (p = 0.54).

CONCLUSIONS

One week of polycarbonate bottle use increased urinary BPA concentrations by two-thirds. Regular consumption of cold beverages from polycarbonate bottles is associated with a substantial increase in urinary BPA concentrations irrespective of exposure to BPA from other sources.

Human body burdens of chemicals used in plastic manufacture

In the last decades, the availability of sophisticated analytical chemistry techniques has facilitated measuring trace levels of multiple environmental chemicals in human biological matrices (i.e. biomonitoring) with a high degree of accuracy and precision. As biomonitoring data have become readily available, interest in their interpretation has increased. We present an overview on the use of biomonitoring in exposure and risk assessment using phthalates and bisphenol A as examples of chemicals used in the manufacture of plastic goods. We present and review the most relevant research on biomarkers of exposure for phthalates and bisphenol A, including novel and most comprehensive biomonitoring data from Germany and the United States. We discuss several factors relevant for interpreting and understanding biomonitoring data, including selection of both biomarkers of exposure and human matrices, and toxicokinetic information.

Bisphenol A levels in blood and urine in a Chinese population and the personal factors affecting the levels

The objective of the study was to describe the background bisphenol A (BPA) levels in urine and serum of a Chinese population without occupational exposure and to examine the personal characteristics influencing these levels. Workers from 10 factories and their family members were recruited and their peripheral blood and spot urine samples were collected. The conjugated and free BPA of the samples was assayed with high-performance liquid chromatography. The exposure levels were checked with 2-independent-samples test, and the potential personal factors influencing exposure levels were analyzed using nonlinear correlation. Of the total of 952 subjects participating in the study, urine and blood samples were taken from 97% and 93% of them, respectively. The detectable rates were 50% for urine samples and 17% for serum samples, given the detection limit of 0.31 microg/L for urine and 0.39 microg/L for serum. The arithmetic mean (AM) and geometric mean (GM) of non-creatinine-adjusted urinary BPA level were 10.45 and 0.87 microg/L, which became 24.93 and 0.38 microg/g Cr after the creatinine level was adjusted; serum BPA levels were 2.84 microg/L (AM) and 0.18 microg/L (GM). Males and those with smoking habit had higher biological burden of BPA. The results indicated that half of the study subjects had detectable BPA in their urine samples. BPA levels were influenced by gender and smoking status. The sources of non-occupational BPA exposures should be explored.

Bisphenol A levels in blood depend on age and exposure

We present two approaches to estimate blood concentrations of Bisphenol A (BPA). Simple kinetic principles were applied to calculate steady state plasma concentrations. A physiologically based model was used to simulate the blood concentration time profile in several age groups exploring the influence of not yet fully developed metabolic capacity on the blood concentrations in the newborn. Both approaches gave concordant results and are in excellent agreement with experimental results [Völkel, W., Colnot, T., Csanady, G.A., Filser, J.G., Dekant, W., 2002. Metabolism and kinetics of bisphenol A in humans at low doses following oral administration. Chem. Res. Toxicol. 15, 1281-1287]. The predictions also agree with published results obtained with a different physiologically based model. According to model simulations, BPA is present in the blood of the normal population at concentrations several orders of magnitude lower than most measurements reported in the literature. At the same external exposure level, the newborn is predicted to have 3 times greater blood concentration than the adult. This is due to the not yet fully developed glucuronidation activity in the newborn, not fully compensated by the unimpaired sulfation pathway. For the highest measured external BPA exposure, the predicted blood concentrations of 2.6 pg/ml (steady state concentration) and 8.2 pg/ml (peak concentration) in the adult are lower than the in vitro concentrations at which inhibiting adiponectin release from human adipocytes and stimulation of beta-cell production and secretion were observed.

Bisphenol-A and the great divide: a review of controversies in the field of endocrine disruption

In 1991, a group of 21 scientists gathered at the Wingspread Conference Center to discuss evidence of developmental alterations observed in wildlife populations after chemical exposures. There, the term "endocrine disruptor" was agreed upon to describe a class of chemicals including those that act as agonists and antagonists of the estrogen receptors (ERs), androgen receptor, thyroid hormone receptor, and others. This definition has since evolved, and the field has grown to encompass hundreds of chemicals. Despite significant advances in the study of endocrine disruptors, several controversies have sprung up and continue, including the debate over the existence of nonmonotonic dose response curves, the mechanisms of low-dose effects, and the importance of considering critical periods of exposure in experimental design. One chemical found ubiquitously in our environment, bisphenol-A (BPA), has received a tremendous amount of attention from research scientists, government panels, and the popular press. In this review, we have covered the above-mentioned controversies plus six additional issues that have divided scientists in the field of BPA research, namely: 1) mechanisms of BPA action; 2) levels of human exposure; 3) routes of human exposure; 4) pharmacokinetic models of BPA metabolism; 5) effects of BPA on exposed animals; and 6) links between BPA and cancer. Understanding these topics is essential for educating the public and medical professionals about potential risks associated with developmental exposure to BPA and other endocrine disruptors, the design of rigorously researched programs using both epidemiological and animal studies, and ultimately the development of a sound public health policy.

An Updated Weight of the Evidence Evaluation of Reproductive and Developmental Effects of Low Doses of Bisphenol A

There is controversy over whether low doses of bisphenol A (BPA, CAS no. 80-05-7) cause reproductive and developmental effects in humans. We update the 2004 weight-of-evidence assessment of an expert panel convened by Harvard's Center for Risk Analysis by critically evaluating over 50 additional studies published between April 2002 and February 2006 that examine in vivo reproductive and developmental toxicity in mammals at doses <or=5 mg/kg-d. Our findings are consistent with the Harvard study: some statistically significant findings in rats and mice exist but they are generally countered by more numerous studies showing no effect for similar endpoints. No effect is marked or consistent across species, doses, and time points. Some mouse studies report morphological changes in testes and sperm and some non-oral mouse studies report morphological changes in female reproductive organs. Owing to lack of first-pass metabolism, results from non-oral studies are of limited relevance to oral human exposure. Human biomonitoring indicates exposures lower than the "low" doses in the reviewed animal studies. Reports of human health impact are very limited and inconsistent. Taken together, the weight of evidence does not support the hypothesis that low oral doses of BPA adversely affect human reproductive and developmental health.

Proteomic biomarkers for prenatal bisphenol A-exposure in mouse immune organs

Many investigators have encountered difficulty in clarifying the risks of exposure to bisphenol A (BPA), an endocrine disrupting chemical in epidemiological studies or animal experiments. In the present study, we developed biomarkers of BPA-induced proteomic alterations in immune organs of mouse offspring that were prenatally exposed to BPA (15 and 300 mg/L of drinking water; they were exposed to 8.9 +/- 1.8 mg of BPA/kg/day and 171.1 +/- 16.8 mg of BPA/kg/day, respectively) that were evaluated in terms of sex, age, and BPA-exposure levels. We performed 2D-gel analyses of samples from various tissues (thymus and spleen), exposure levels, sex, and ages (3- and 7-week-old) (N = 48), and found seven proteins that were altered in a BPA dose-dependent manner. Among them, we further studiedapo-AI, DPPIII, and VAT1, which are suspected to be associated with endocrine disorders. By performing Western blots, we confirmed BPA upregulation of all three proteins. Moreover, the apo-AI mRNA levels were increased in a BPA dose-dependent manner in 3- and 7-week-old female mice. Females and young offspring were somewhat more sensitive to protein alterations than others. Our study, which is based on proteome analyses, suggests that apo-AI, DPPIII, and VAT represent protein biomarkers for BPA and provide useful mechanistic clues for BPA-induced endocrine disruption.

Maternal and fetal exposure to bisphenol A in Korea

Bisphenol A (BPA) is a well-known endocrine disrupter used widely. Despite the potential risk of human exposure to BPA, little information exists concerning maternal and fetal exposure to BPA during pregnancy in Korea. This study purposed to evaluate the correlation between maternal and fetal exposure, and to determine exposure levels to BPA in Korean pregnant women and their fetuses. Maternal blood and umbilical cord blood were collected from 300 subjects, and total BPA levels were measured. Blood BPA concentrations ranged from non-detectable to 66.48 microg/L in pregnant women and from non-detectable to 8.86 microg/L in umbilical cords. Serum BPA levels in most pregnant women were higher than in corresponding fetal umbilical cords and a positive correlation was found between in maternal and fetal BPA concentrations (p<0.05).

Derivation of a bisphenol A oral reference dose (RfD) and drinking-water equivalent concentration

Human exposure to bisphenol A (BPA) is due to that found in the diet, and BPA and its metabolites were detected at parts per billion (or less) concentrations in human urine, milk, saliva, serum, plasma, ovarian follicular fluid, and amniotic fluid. Adverse health effects in mice and rats may be induced after parenteral injection or after massive oral doses. Controlled ingestion trials in healthy adult volunteers with 5 mg d16-BPA were unable to detect parent BPA in plasma despite exquisitely sensitive (limit of detection = 6 nM) methods, but by 96 h 100% of the administered dose was recovered in urine as the glucuronide. The extensive BPA glucuronidation following ingestion is not seen after parenteral injection; only the parent BPA binds plasma proteins and estrogen receptors (ER). The hypothesis that BPA dose-response may be described by a J- or U-shape curve was not supported by toxicogenomic data collected in fetal rat testes and epididymes (after repeated parenteral exposure at 2-400,000 microg/kg-d), where a clear monotonic dose-response both in the numbers of genes and magnitude of individual gene expression was evident. There is no clear indication from available data that the BPA doses normally consumed by humans pose an increased risk for immunologic or neurologic disease. There is no evidence that BPA poses a genotoxic or carcinogenic risk and clinical evaluations of 205 men and women with high-performance liquid chromatography (HPLC)-verified serum or urinary BPA conjugates showed (1) no objective signs, (2) no changes in reproductive hormones or clinical chemistry parameters, and (3) no alterations in the number of children or sons:daughters ratio. Results of benchmark dose (BMD10 and BMDL10) calculations and no-observed-adverse-effect level (NOAEL) inspections of all available and reproducible rodent studies with oral BPA found BMD and NOAEL values all greater than the 5 mg/kg-d NOAELs from mouse and rat multigeneration reproduction toxicity studies. While allometric and physiologically based pharmacokinetic (PBPK) models were constructed for interspecies scaling of BPA and its interaction with ER, multigeneration feeding studies with BPA at doses spanning 5 orders of magnitude failed to identify signs of developmental toxicity or adverse changes in reproductive tract tissues; the 5-mg/kg-d NOAELs identified for systemic toxicity in rats and mice were less than the oral NOAELs for reproductive toxicity. Thus, it is the generalized systemic toxicity of ingested BPA rather than reproductive, immunologic, neurobehavioral, or genotoxic hazard that represents the point of departure. Using U.S. Environmental Protection Agency (EPA) uncertainty factor guidance and application of a threefold database uncertainty factor (to account for the fact that the carcinogenic potential of transplacental BPA exposure has yet to be fully defined and comprehensive neurobehavioral and immunotoxicologic evaluations of BPA by relevant routes and at relevant doses have yet to be completed) to the administered dose NOAEL results in an oral RfD of 0.016 mg/kg-d. Assuming the 70-kg adult consumes 2 L of water each day and adopting the default 20% U.S. EPA drinking water relative source contribution yields a 100 microg/L BPA total allowable concentration (TAC).

Temporal variability and predictors of urinary bisphenol A concentrations in men and women

BACKGROUND

Bisphenol A (BPA) is used to manufacture polymeric materials, such as polycarbonate plastics, and is found in a variety of consumer products. Recent data show widespread BPA exposure among the U.S. population.

OBJECTIVE

Our goal in the present study was to determine the temporal variability and predictors of BPA exposure.

METHODS

We measured urinary concentrations of BPA among male and female patients from the Massachusetts General Hospital Fertility Center.

RESULTS

Between 2004 and 2006, 217 urine samples were collected from 82 subjects: 45 women (145 samples) and 37 men (72 samples). Of these, 24 women and men were partners and contributed 42 pairs of samples collected on the same day. Ten women became pregnant during the follow-up period. Among the 217 urine samples, the median BPA concentration was 1.20 microg/L, ranging from below the limit of detection (0.4 microg/L) to 42.6 microg/L. Age, body mass index, and sex were not significant predictors of urinary BPA concentrations. BPA urinary concentrations among pregnant women were 26% higher (-26%, +115%) than those among the same women when not pregnant (p > 0.05). The urinary BPA concentrations of the female and male partner on the same day were correlated (r = 0.36; p = 0.02). The sensitivity of classifying a subject in the highest tertile using a single urine sample was 0.64.

CONCLUSION

We found a nonsignificant increase in urinary BPA concentrations in women while pregnant compared with nonpregnant samples from the same women. Samples collected from partners on the same day were correlated, suggesting shared sources of exposure. Finally, a single urine sample showed moderate sensitivity for predicting a subject's tertile categorization.

Downregulation of peritoneal macrophage activity in mice exposed to bisphenol A during pregnancy and lactation

Bisphenol A (BPA) is an environmental endocrine disrupter that is known to be transferred to the fetus via the placenta and to the neonate via milk. In this study, we investigated BPA-induced alterations of the activities of murine peritoneal macrophages in dams and 7 week old offspring of dams exposed to BPA from gestational day 7 until lactation on day 21 after delivery, i.e. 34-36 days. BPA was administered in drinking water at three doses, 15, 75, and 300 mg/L. Dams were sacrificed 21 days after delivery and offspring at the age of 7 weeks. Peritoneal macrophages were cultured in the presence of LPS or LPS plus IFN-gamma for 2 or 4 days. We found that nitric oxide (NO) production by maternal macrophages was significantly decreased in a BPA-dose dependent manner. However, while a significant reduction of NO production by macrophages in the offspring was observed at BPA concentrations of 75 mg/L and 300 mg/L in drinking water, this effect was not seen at the lowest concentration of 15 mg/L. Similar inhibition of tumor necrosis factor-alpha (TNF-alpha) production was observed with macrophages from both BPA-exposed dams and offspring. Thus, our results suggest that exposure to BPA during gestation and lactation induces downregulation of the activities of macrophages in both dams and offspring.

Temporal stability of the conjugated species of bisphenol A, parabens, and other environmental phenols in human urine

Human exposure to environmental phenols can be assessed by measuring the urinary concentrations of these compounds or their metabolites. Total concentrations, which include both free and conjugated (i.e., glucuronide and sulfated) species, are usually reported. Because conjugation may reduce the potential bioactivity of the compounds, measuring separately both the concentrations of free and conjugated species can be of interest. Data on the stability of these conjugated species in urine is critical if the concentrations of free and conjugated species are to be compared. Over a period of 6 months, we investigated the stability of the urinary conjugates of eight environmental phenols (bisphenol A, 2-hydroxy-4-metoxybenzophenone or benzophenone-3, triclosan, 2,5-dichlorophenol, methyl paraben, ethyl paraben, propyl paraben, and butyl paraben) at three storage conditions (room temperature, 4 degrees C, and -70 degrees C). After collection, conjugated species appeared to be stable for at least 7 days when the urine was stored at 4 degrees C, and for at least 180 days at -70 degrees C. By contrast, some of the environmental phenol conjugates commenced to degrade within 24 h after collection when the urine was stored at room temperature although the total concentrations remained relatively constant for at least 30 days. These results suggest that if the concentrations of free and conjugated species will be used for exposure assessment purposes, urine specimens collected for analysis of environmental phenols should be kept at room temperature for the shortest possible time after collection.

Human exposure to bisphenol A (BPA)

The plastic monomer and plasticizer bisphenol A (BPA) is one of the highest volume chemicals produced worldwide. BPA is used in the production of polycarbonate plastics and epoxy resins used in many consumer products. Here, we have outlined studies that address the levels of BPA in human tissues and fluids. We have reviewed the few epidemiological studies available that explore biological markers of BPA exposure and human health outcomes. We have examined several studies of levels of BPA released from consumer products as well as the levels measured in wastewater, drinking water, air and dust. Lastly, we have reviewed acute metabolic studies and the information available about BPA metabolism in animal models. The reported levels of BPA in human fluids are higher than the BPA concentrations reported to stimulate molecular endpoints in vitro and appear to be within an order of magnitude of the levels needed to induce effects in animal models.