Chemical change of chlorinated bisphenol A by ultraviolet irradiation and cytotoxicity of their products on Jurkat cells

Chlorinated derivatives of bisphenol A (ClBPAs) have been detected in wastewater from waste paper recycling plants. BPA and ClBPAs are always exposed to ultraviolet (UV) radiation in the environment and consequently various photoproducts might be produced. Acute cytotoxicity of photoproducts of BPA and ClBPAs are not known. In this study, we investigated the cytotoxicity and chemical structure of photoproducts of BPA and ClBPAs (3-chlorobisphenol A (3-ClBPA), 3,3′-dichlorobisphenol A (3,3′-diClBPA) and 3,3′,5-trichlorobisphenol A (3,3′,5-triClBPA)) after UV irradiation (UVA, UVB and UVC). The toxicities of photoproducts on Jurkat cells were determined by Alamar Blue assay, and the chemical structures of the photoproducts were identified using GC/MS. The cytotoxicities of 3-ClBPA and 3,3′-diClBPA were higher than that of BPA and 3,3′,5-triClBPA. In addition, the toxicities of ClBPAs were increased by the irradiation of UVB and UVC at 100 J/cm² and decreased at 1000 J/cm² in comparison with those at 100 J/cm², indicating that their structures had changed. 3-Hydroxybisphenol A (3-OHBPA) was detected in the photoproducts of 3-ClBPA irradiated with UVB and UVC at 100 J/cm², and 3-OHBPA and 3-chloro-3′-hydroxybisphenol A (3-Cl-3′-OHBPA) were detected in those of 3,3′-diClBPA. However, these hydroxylated BPAs were not detected in the photoproducts exposed to 1000 J/cm². The cytotoxicity of 3-OHBPA was the almost same as ClBPAs after UVB and UVC irradiation. These results indicate that the formation of hydroxylated BPAs might contribute to the increase in toxicity caused by UV irradiation.     

盐酸小檗碱诱导Jurkat细胞凋亡的研究

目的本研究旨在观察盐酸小檗碱能否抑制Jurkat细胞的增殖、并对其作用机制进行初步探讨。从而为临床上应用治疗急性T淋细胞白血病提供实验依据。方法MTT比色法检测盐酸小檗碱对Jurkat细胞增殖的影响;AO／EB染色法观察细胞凋亡的形态学改变;TUNEL方法检测细胞凋亡的生化功能变化。结果盐酸小檗碱对Jurkat细胞的生长有抑制作用,呈现明显的剂量和时间依赖性,24h、48h、72h、96h、120h的IC50分别为107．5567μg·mL^-1、23．5600μg·mL^-1、10．8069μg·mL^-1、9．2660μg·mL^-1和2．7121μg·mL^-1盐酸小檗碱处理Jurkat细胞可见典型的细胞凋亡形态学改变;TUNEL可见深棕色凋亡细胞。结论盐酸小檗碱能有效地抑制体外Jurkat细胞的增殖,其作用可能是通过诱导Jurkat细胞凋亡有关。     

Mitochondrial signaling pathway is also involved in bisphenol A induced germ cell apoptosis in testes

Bisphenol A (BPA) is a potential endocrine disruptor and testicular toxicant. An earlier study showed that BPA-induced germ cell apoptosis through the Fas/FasL apoptotic pathway. In the present study, we aimed to investigate whether the mitochondrial pathway is also involved in the process of BPA-mediated germ cell apoptosis in testes. Male mice were administered with BPA (160 or 480 mg/kg) by gavage daily from postnatal day 35 (PND35) to PND49. Germ cell apoptosis in testes was determined by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling (TUNEL). As expected, the number of TUNEL+ germ cells per tubule and the percentage of tubules with TUNEL+ germ cells were significantly increased in testes of mice treated with BPA during puberty. TUNEL+ germ cells were observed mainly in stages VII–VIII seminiferous tubules in testes. An increase in the level of Fas and FasL was observed in testes of mice exposed to BPA during puberty. In addition, pubertal BPA exposure evoked the activation of caspase-8 and caspase-3 in testes. Interestingly, pubertal BPA exposure also caused the translocation of cytochrome c from mitochondria into cytosol. In addition, pubertal BPA exposure upregulated the level of Bax and active caspase-9 in testes. Taken together, these results suggest that pubertal BPA exposure induces germ cell apoptosis in testes through not only the Fas/FasL signaling pathway but also the mitochondrial apoptotic pathway.     

Induction of reactive oxygen species by bisphenol A and abrogation of bisphenol A-induced cell injury by DJ-1.

DJ-1 was first identified as an activated ras-dependent oncogene. DJ-1 is related to male fertility, and its expression in sperm decreases in response to exposure to a number of reproductive toxicants. DJ-1 has been associated with the onset of familial Parkinson's disease (PD) in humans, and has been found to have activity against oxidative damage by eliminating reactive oxygen species (ROS). In this study, we investigated the role of DJ-1 in oxidative stresses by administration of bisphenol A (BPA), which has been reported to induce oxidative stress in rodents, to male mice and cultured cells. In male mice, we found that BPA significantly increased the expression level of DJ-1 in the sperm and brain. In cultured Neuro2a and GC1 cells, we found that BPA induced ROS production and significantly compromised mitochondrial function concomitant with elevated expression and oxidization of DJ-1. DJ-1 was found to maintain the complex I activity against BPA-induced oxidative stress after the localization in mitochondria. The results showed that DJ-1 plays a role in the prevention of mitochondrial injury-induced cell death.     

双酚A对子宫肌瘤细胞体外增殖的研究

目的探讨环境雌激素双酚A(BPA)对人离体子宫肌瘤细胞增殖的影响及相关机制。方法进行人子宫肌瘤细胞原代、传代培养及鉴定。采用噻唑蓝(MTT)法测定用3种剂量的BPA(25×10-7、50×10-7、100×10-7mol/L)分别干预24、48、72h及溶剂对照组细胞的增殖情况;采用反转录-聚合酶链反应(RT-PCR)测定雌激素受体(ER)mRNA,胰岛素样生长因子(IGF)-1mRNA,血管内皮细胞生长因子(VEGF)-1mRNA的表达。结果100×10-7mol/LBPA作用于子宫肌瘤细胞24、48、72h,及50×10-7mol/LBPA作用48、72h可促进子宫肌瘤细胞增殖,并使ER mRNA、IGF mRNA、VEGF mRNA的表达呈上升趋势,与空白对照组比较,差异均有统计学意义(P<0.05,P<0.01)。结论BPA引起细胞增殖可能是通过ER使IGF、VEGF表达增加而引起的,且BPA的促增殖作用存在时间和剂量依赖关系。     

Rat hyperactivity by bisphenol A, but not by its derivatives, 3-hydroxybisphenol A or bisphenol A 3,4-quinone

Detoxification in the central nervous system is largely unknown. The mechanism of neurotoxicity of bisphenol A, a toxic environmental chemical remains obscure. We examined the effects of bisphenol A, and its derivatives, 3-hydroxybisphenol A and bisphenol A 3,4-quinone on rat behavior as possible metabolites of bisphenol A. A single intracisternal administration of bisphenol A (20 μg equivalent to 87 nmol) into 5-day-old male Wistar rats caused significant hyperactivity at 4-5 weeks of age. It was about 1.3 fold more active in the nocturnal phase than control rats. However, neither 3-hydroxybisphenol A nor bisphenol A 3,4-quinone at the same amount (87 nmol) increased the spontaneous motor activity. Gas chromatographic-mass spectrometric (GC-MS) analyses of the treated brain revealed that 7% of the parent chemical resided in the brain at 8 weeks of age, but its derivatives were not found. This suggested a difference in metabolic turnover of these compounds or a difference in their stabilities. We conclude that bisphenol A per se caused hyperactivity in the rat, eliminating the possibility that possible metabolic forms of bisphenol A, 3-hydroxybisphenol A and bisphenol A 3,4-quinone have the ability to elicit rat hyperactivity, probably because of longer-lasting residence of the parent compound in the brain.     

Epigenetic influences of low-dose bisphenol A in primary human breast epithelial cells

Substantial evidence indicates that exposure to bisphenol A (BPA) during early development may increase breast cancer risk later in life. The changes may persist into puberty and adulthood, suggesting an epigenetic process being imposed in differentiated breast epithelial cells. The molecular mechanisms by which early memory of BPA exposure is imprinted in breast progenitor cells and then passed onto their epithelial progeny are not well understood. The aim of this study was to examine epigenetic changes in breast epithelial cells treated with low-dose BPA. We also investigated the effect of BPA on the ERα signaling pathway and global gene expression profiles. Compared to control cells, nuclear internalization of ERα was observed in epithelial cells preexposed to BPA. We identified 170 genes with similar expression changes in response to BPA. Functional analysis confirms that gene suppression was mediated in part through an ERα-dependent pathway. As a result of exposure to BPA or other estrogen-like chemicals, the expression of lysosomal-associated membrane protein 3 (LAMP3) became epigenetically silenced in breast epithelial cells. Furthermore, increased DNA methylation in the LAMP3 CpG island was this repressive mark preferentially occurred in ERα-positive breast tumors. These results suggest that the in vitro system developed in our laboratory is a valuable tool for exposure studies of BPA and other xenoestrogens in human cells. Individual and geographical differences may contribute to altered patterns of gene expression and DNA methylation in susceptible loci. Combination of our exposure model with epigenetic analysis and other biochemical assays can give insight into the heritable effect of low-dose BPA in human cells.     

Migration of BADGE (bisphenol A diglycidyl-ether) and BFDGE (bisphenol F diglycidyl-ether) in canned seafood

Migration of potentially toxic materials used for the lining of commercial can goods remains an important issue, especially with respect to certain types of processed foods. Seafood is one type where more information is needed with respect to other ingredients used for adding value to fishery products. Most cans are internally coated with starters of resins such as bisphenol A diglycidyl-ether (BADGE) and bisphenol F diglycidyl-ether (BFDGE), both considered as toxic compounds. Several seafood products, sardines, tuna fish, mackerel, mussels, cod and mackerel eggs, were manufactured in different conditions changing covering sauce, time and temperature of storage and heat-treated for sterilization in cans. Migration kinetics of BADGE and BFDGE from varnish into canned products were evaluated by HPLC in 70 samples after 6, 12 or 18 months of storage. Results showed that there is no migration of BADGE in tuna fish, sardines, mussels or cod. However, migration of BFDGE occurs in all species, in a storage time-dependent way and content of fat, although migration of these compounds is not affected by sterilization conditions. All samples analyzed presented values lower than 9 mg BADGE/kg net product without exceeding European limits. However, concerning BFDGE migration, European legislation does not allow the use and/or the presence of BFDGE. Main migration takes place in mackerel reaching the highest values, 0.74 mg BFDGE/kg and 0.34 mg BADGE/kg net product, in red pepper sauce.     

Lactational transfer of bisphenol A in Sprague-Dawley rats

Bisphenol A (BPA), an important industrial chemical to which humans are exposed on a daily basis, has long been associated with endocrine disruption in experimental animal models. Such exposures are of concern, particularly during fetal and early neonatal periods, because of greater vulnerability of developing organs to aberrant endocrine signaling. Although rarely reported, information about internal exposures to the receptor-active aglycone form of BPA during the perinatal period is essential to accurate assessment of potential risks. Lactating Sprague-Dawley dams were treated by daily gavage with 100 μg/kg bw d6-BPA starting at birth. Conjugated and aglycone forms of BPA were then measured by using LC/MS/MS in milk from lactating dams on PND 7 and in serum from dams and their pups on PND 10. All samples were collected 1h after dosing, a time selected to produce nearly maximal levels. While aglycone BPA was detected in all dam serum and milk samples, none was detected in pup serum (<0.2 nM). Doses delivered to pups lactationally, estimated from milk concentrations and body weights, were 300-fold lower than the dose administered to the dams. Similarly, serum concentrations of total BPA in pups were 300-fold lower than those in their dams. Furthermore, plasma concentrations of total BPA in PND 10 rat pups were 500-fold lower than peak levels achieved following direct oral delivery of the same dose to the same age pups. These findings of significant dose attenuation for the active aglycone form of BPA, relative to that of the dam, suggest high potency for toxicological effects derived exclusively from lactational transfer. Alternatively, studies that include lactational exposure and report minimal effects from BPA should consider the possibility that inadequate internal exposures were achieved during the critical postnatal period.     

Excretion of bisphenol A into rat milk

Bisphenol A (BPA), an endocrine-disrupting chemical, is widely used in the production of polycarbonate plastic and epoxy resins. This study analyzed the BPA concentration in rat milk, in order to assess the risk of BPA transfer to the offspring via milk. The rats ingested BPA by oral administration or by drinking the water in a polycarbonate bottle, and the milk samples were collected using an automated experimental milker. The BPA concentration in the samples of milk, drinking water, and food was analyzed by LC/MS. In the case of milk samples obtained from rats injected with BPA at 2, 4, 8, and 24?h prior to milking, the BPA concentrations were 0.462?±?0.182 ppm, 0.138?±?0.0185 ppm, 0.080?±?0.0197 ppm, and 0.0232?±?0.0051 ppm, respectively. Also, in the cases of the water sample left in polycarbonate bottle and the milk sample obtained from rats provided it as drinking water, the concentrations of BPA were 0.000332?±?0.00015 ppm and 0.0184?±?0.0050 ppm, respectively. The results indicate that the BPA administered to the dams was transferred to their milk, and that BPA concentration in milk was higher at the early period after the single bolus dose. Additionally, these results reveal that sequential elution of BPA from polycarbonate containers in a much diluted form would undergo bioaccumulation in dams and likely be transferred to pups via milk in a much concentrated form.     

Mitochondrion-mediated apoptosis is involved in reproductive damage caused by BPA in male rats

Bisphenol A (BPA) is a widely used environmental endocrine disruptor. Many studies have reported that BPA exposure shows reproductive toxicity and causes apoptosis in spermatogenic cells. However, few studies have investigated the relationship between the mitochondrial pathway and BPA-induced apoptosis. This study investigated the role of the mitochondrial pathway in apoptosis induced by BPA, which resulted in compromised male rat spermatogenesis and reproductive damage. Rats were exposed to various BPA concentrations (0, 50, 100, or 200 mg of BPA/kg body weight per day), and factors in the mitochondrial signal transduction pathway and the apoptosis indices of spermatogenic cells were measured and sperm characteristics were analyzed. Our data revealed that BPA exposure increased the protein and mRNA levels of cytochrome C, apoptosis-inducing factor, caspase-3/9, and Bax; caspase-3 and caspase-9 activities; and the apoptosis indices of spermatogenic cells. In addition, abnormal structure of mitochondria and decreased protein and gene levels of Bcl-2 were observed following BPA exposure. These results suggest that apoptosis in the mitochondrial pathway mediates compromised reproductive system function caused by BPA exposure.     

GC-TQ-MS/MS测定生理盐水注射液中双酚A

目的 建立生理盐水注射液中双酚A（BPA）残留量的测定方法。方法 采用气相色谱-三重四级杆（GC-TQ-MS/MS）联用技术,测定了5批生理盐水注射液中BPA的残留量,每批平行测定6次,且每次分别在5、10、20 μg/kg 3个添加水平下进行加样回收,每水平分别测定3次。结果 所测5批生理盐水注射液中BPA质量分数分别为27.01、11.80、15.73、22.28、9.03 μg/kg;RSD分别为2.3%、4.2%、3.2%、4.4%、1.9%;平均加样回收率在79.9%～99.3%,RSD均小于4.1%。BPA在10～200 μg/L内呈良好的线性关系,检测限为1.25 μg/kg。结论 该法简便快速、灵敏性高,可用于生理盐水注射液中BPA残留量的测定。     

Pharmacokinetics of bisphenol A in neonatal and adult Sprague-Dawley rats

Bisphenol A (BPA) is an important industrial chemical used in the manufacture of polycarbonate plastic products and epoxy resin-based food can liners. The presence of BPA in urine of > 90% of Americans aged 6-60 suggests ubiquitous and frequent exposure. The current study used LC/MS/MS to measure serum pharmacokinetics of aglycone (active) and conjugated (inactive) BPA in adult and neonatal Sprague-Dawley rats by oral and injection routes. Deuterated BPA was used to avoid issues of background contamination. Linear pharmacokinetics were observed in adult rats treated orally in the range of 0-200 μg/kg bw. Evidence for enterohepatic recirculation of conjugated, but not aglycone, BPA was observed in adult rats. Significant inverse relationships were observed between postnatal age and measures of internal exposures to aglycone BPA and its elimination. In neonatal rats treated orally, internal exposures to aglycone BPA were substantially lower than from subcutaneous injection. The results reinforce the critical role for first-pass Phase II metabolism of BPA in gut and liver after oral exposure that attenuates internal exposure to the aglycone form in rats of all ages. The internal exposures to aglycone BPA observed in adult and neonatal rats following a single oral dose of 100 μg/kg bw are inconsistent with effects mediated by classical estrogen receptors based on binding affinities. However, an impact on alternative estrogen signaling pathways that have higher receptor affinity cannot be excluded in neonatal rats. These findings emphasize the importance of matching aglycone BPA internal dosimetry with receptor affinities in experimental animal studies reporting toxicity.     

异鼠李素诱导A549细胞凋亡的研究

目的观察异鼠李素是否能诱导人肺腺癌细胞株A549细胞凋亡及相关基因的变化。方法20μg/ml异鼠李素处理A549细胞,光镜电镜下观察细胞形态;进行集落形成实验,MTT法测细胞生长抑制率;流式细胞仪检测凋亡峰及bax,bcl-2等凋亡相关基因的表达。结果10～640μg/ml异鼠李素可抑制A549细胞生长,抑制率有剂量依赖性。流式细胞仪检测20μg/ml异鼠李素处理后出现明显凋亡峰;药物可使bax表达上调,bcl-2表达明显下降,表达改变有浓度依赖性。结论异鼠李素可抑制A549细胞生长,诱导其凋亡,其诱导凋亡的作用与凋亡相关基因抗凋亡基因bcl-2表达明显下调,bax表达上调有关。     

双酚A对颗粒细胞激素生成及相关甾体生成酶的影响

目的 探讨双酚A(BPA)对大鼠颗粒细胞雌、孕激素生成及相关甾体生成酶的影响.方法 采用大鼠卵巢颗粒细胞进行体外培养,72 h后给予不同浓度的BPA(0、10-7、10-6、10-5、10-4 M)处理,继续培养48 h后,收集细胞培养液,用超敏感的固相放射免疫方法测定孕酮和雌二醇(E2)的浓度;用荧光实时定量PCR法测定颗粒细胞内芳香化酶(P450arom)、胆固醇侧链裂解酶(P450Scc)和类固醇合成急性调节蛋白(StAR)的mRNA表达水平.结果 在BPA作用下,颗粒细胞孕酮分泌量在10-7M到10-5M组逐渐升高(P＜0.05),但在10-4M剂量组出现意外陡降(P＜0.01);而E2的分泌量则随BPA浓度的增加而下降(P＜0.01).P450arom mRNA表达显著降低;P450Scc表达量亦在10-7M到10-5M组逐渐升高(P＜0.05),而10-4M组出现显著降低(P＜0.01).StAR mRNA表达在10-4M组增高(P＜0.05).结论 BPA能直接作用于卵巢颗粒细胞,通过作用于P450arom,P450Scc等相关酶的表达以及类固醇合成的限速因子-StAR的表达,而影响颗粒细胞雌孕激素的分泌.     

Role of DNA methylation in bisphenol A exposed mouse spermatocyte

As a widespread environmental contaminant, bisphenol A (2,2-bis(4-hydroxyphenyl)propane, BPA) has been implicated in male reproductive function injury. Previous studies have investigated the mechanisms of DNA damage and oxidative stress caused by BPA; however, little is known regarding its impact on DNA methylation. In this paper, we assessed the adverse effects of BPA on mouse spermatocytes and investigated a potential role of DNA methylation. We demonstrated that BPA exposure inhibited cell proliferation, reduced the DNA replication capacity, and triggered apoptosis in GC-2 cells. In addition, the global DNA methylation levels increased, and the relative expression levels of DNA methyltransferases (DNMTs) varied following BPA exposure. Thousands of distinct methylated sites were screened using microarray analysis. The expressions of myosin-binding protein H (mybph) and protein kinase C δ (prkcd) were verified to be regulated by DNA methylation. These findings indicate that BPA had toxicity in spermatocytes, and DNA methylation may play a vital role in the regulation of BPA-triggered spermatocyte toxicity.     

In utero bisphenol A exposure disrupts germ cell nest breakdown and reduces fertility with age in the mouse

Bisphenol A (BPA) is a known reproductive toxicant in rodents. However, the effects of in utero BPA exposure on early ovarian development and the consequences of such exposure on female reproduction in later reproductive life are unclear. Thus, we determined the effects of in utero BPA exposure during a critical developmental window on germ cell nest breakdown, a process required for establishment of the finite primordial follicle pool, and on female reproduction. Pregnant FVB mice (F0) were orally dosed daily with tocopherol-striped corn oil (vehicle), diethylstilbestrol (DES; 0.05 μg/kg, positive control), or BPA (0.5, 20, and 50 μg/kg) from gestational day 11 until birth. Ovarian morphology and gene expression profiles then were examined in F1 female offspring on postnatal day (PND) 4 and estrous cyclicity was examined daily after weaning for 30 days. F1 females were also subjected to breeding studies with untreated males at three to nine months. The results indicate that BPA inhibits germ cell nest breakdown via altering expression of selected apoptotic factors. BPA also significantly advances the age of first estrus, shortens the time that the females remain in estrus, and increases the time that the females remain in metestrus and diestrus compared to controls. Further, F1 females exposed to low doses of BPA exhibit various fertility problems and have a significantly higher percentage of dead pups compared to controls. These results indicate that in utero exposure to low doses of BPA during a critical ovarian developmental window interferes with early ovarian development and reduces fertility with age.     

In vitro assay of hydrolysis and chlorohydroxy derivatives of bisphenol A diglycidyl ether for estrogenic activity

Bisphenol A diglycidyl ether (BADGE) is an epoxy resin monomer. Epoxy-based solution coatings are used in many applications as additives for a variety of plastic coatings in food packaging. It is well known that unreacted BADGE can migrate from epoxy-based packing materials into foods. Not only BADGE but also its derivatives can easily migrate into foods and it is likely that we intake BADGE and its derivatives through food or drink. Recently, endocrine disrupting chemicals (EDCs) have attracted attention because they have been shown to affect reproduction in wildlife. The estrogenic activity of BADGE derivatives has not previously been investigated. Therefore, we investigated the estrogenic activity of the BADGE derivatives, dihydrolysed BADGE (BADGE-4OH) and chlorohydroxy BADGE (BADGE-2Cl), using breast cancer cell (T47D) proliferation assay and estrogen receptor (ER) () binding assay. These chemicals exhibited T47D cell proliferation at concentrations of 10⁻¹⁴–10⁻⁴ . However, these chemicals did not bind to ER () in the binding assay.     

Potent estrogenic metabolites of bisphenol A and bisphenol B formed by rat liver S9 fraction: their structures and estrogenic potency.

We previously demonstrated that the estrogenicity of either bisphenol A [BPA; 2,2-bis(4-hydroxyphenyl)propane] or bisphenol B [BPB; 2,2-bis(4-hydroxyphenyl)butane] was increased several times after incubation with rat liver S9 fraction (Yoshihara et al., 2001). This metabolic activation, requiring both microsomal and cytosolic fractions, was observed with not only rat liver, but also human, monkey, and mouse liver S9 fractions. To characterize the active metabolites of BPA and BPB, we investigated the structures of the isolated active metabolites by negative mode LC/MS/MS and GC/MS. The active metabolite of BPA gave a negative mass peak at [M-H](-) 267 on LC/MS and a single daughter ion at m/z 133 on MS/MS analysis, suggesting an isopropenylphenol dimer structure. Finally, this active metabolite was confirmed to be identical with authentic 4-methyl-2,4-bis(p-hydroxyphenyl)pent-1-ene (MBP) by means of various instrumental analyses. The corresponding peaks of the BPB metabolite were [M-H](-) 295 and m/z 147, respectively, suggesting an isobutenylphenol dimer structure. Further, coincubation of BPA and BPB with rat liver S9 afforded an additional active metabolite(s), which gave a negative mass peak at [M-H](-) 281 and two daughter ion peaks at m/z 133 and m/z 147 on MS/MS analysis. These results strongly suggest that the active metabolite of either BPA or BPB might be formed by recombination of a radical fragment, a one-electron oxidation product of carbon-phenyl bond cleavage. It is noteworthy that the estrogenic activity of MBP, the active metabolite of BPA, is much more potent than that of the parent BPA in several assays, including two reporter assays using a recombinant yeast expressing human estrogen receptor alpha and an MCF-7-transfected firefly luciferase plasmid.     

Extrapolation of plasma clearance to understand species differences in toxicokinetics of bisphenol A

1.?Understanding species differences in the toxicokinetics of bisphenol A (BPA) is central to setting acceptable exposure limits for human exposures to BPA. BPA toxicokinetics have been well studied, with controlled oral dosing studies in several species and across a wide dose range.

2.?We analyzed the available toxicokinetic data for BPA following oral dosing to assess potential species differences and dose dependencies. BPA is rapidly conjugated and detoxified in all species. The toxicokinetics of BPA can be well described using non-compartmental analyses.

3.?Several studies measured free (unconjugated) BPA in blood and reported area under the curve (AUC) of free BPA in blood of mice, rats, monkeys, chimpanzees and humans following controlled oral doses. Extrinsic clearance was calculated and analyzed across species and dose using allometric scaling.

4.?The results indicate free BPA clearance is well described using allometric scaling with high correlation coefficients across all species and doses up to 10?mg/kg. The results indicate a human equivalent dose factor (HEDf) of 0.9 is appropriate for extrapolating a point of departure from mice and rats to a human equivalent dose (HED), thereby replacing default uncertainty factors for animal to human toxicokinetics.