Persistent halogenated organic pollutants in follicular fluid of women undergoing in vitro fertilization from China: Occurrence, congener profiles, and possible sources

Microplastic Passage through the Fish and Crayfish Digestive Tract Alters Particle Surface Properties

Most studies on the effects of organisms on microplastic characteristics have focused on microorganisms, while the impact of animal feeding behavior, particularly in aquatic species like fish and decapod crustaceans, has been less explored. This study examines how polyethylene spherical microplastics (275 μm in diameter) passing through the digestive tracts of crucian carp (Carassius carassius) and Australian crayfish (Cherax quadricarinatus) affect surface properties, particle size, and bacterial colonization. The species were fed diets with or without microplastics. The particles underwent two rounds of passage through the digestive tracts and were then exposed to known bacterial densities. Surface damage, size, and biofilm coverage were analyzed using scanning electron microscopy, while alterations in surface chemical composition were assessed through Fourier transform infrared spectroscopy with attenuated total reflectance, and the formation and penetration of nanoplastics in gut tissues and glands were determined using Py-GC/MS. Results show that the passage significantly altered surface properties and reduced microplastic size, without affecting chemical composition or nanoplastic penetration into tissues. These changes promoted bacterial colonization compared to controls. The findings suggest that animal feeding activity may play an important role in the mechanical fragmentation of microplastics in aquatic environments, potentially leading to their faster degradation.

Which is the current knowledge on man-made endocrine- disrupting chemicals in follicular fluid? An overview of effects on ovarian function and reproductive health

The increase in female reproductive disorders, such as polycystic ovary syndrome, endometriosis, and diminished ovarian reserve that lead to subfertility and infertility, has encouraged researchers to search and discover their underlying causes and risk factors. One of the crucial factors that may influence the increasing number of reproductive issues is environmental pollution, particularly exposure to man-made endocrine-disrupting chemicals (EDCs). EDCs can interfere with the ovarian microenvironment, impacting not only granulosa cell function but also other surrounding ovarian cells and follicular fluid (FF), which all play essential roles for oocyte development, maturation, and overall reproductive function. FF surrounds developing oocytes within an ovarian follicle and represents a dynamic milieu. EDCs are usually found in biological fluids, and FF is therefore of interest in this respect. This narrative review examines the current knowledge on specific classes of EDCs, including industrial chemicals, pesticides, and plasticizers, and their known effects on hormonal signaling pathways, gene expression, mitochondrial function, oxidative stress induction, and inflammation in FF. We describe the impact of EDCs on the development of reproductive disorders, oocyte quality, menstrual cycle regulation, and their effect on assisted reproductive technique outcomes. The potential transgenerational effects of EDCs on offspring through animal and first-human studies has been considered also. While significant progress has been made, the current understanding of EDCs' effects on ovarian function, particularly in humans, remains limited, underscoring the need for further research to clarify actions and effects of EDCs in the ovary.

Advances in polychlorinated biphenyls-induced female reproductive toxicity

Polychlorinated biphenyls (PCBs) are a class of endocrine-disrupting chemicals (EDCs) widely present in the environment. PCBs have been of concern due to their anti/estrogen-like effects, which make them more toxic to the female reproductive system. However, there is still a lack of systematic reviews on the reproductive toxicity of PCBs in females, so the adverse effects and mechanisms of PCBs on the female reproductive system were summarized in this paper. Our findings showed that PCBs are positively associated with lower pregnancy rate, hormone disruption, miscarriage and various reproductive diseases in women. In animal experiments, PCBs can damage the structure and function of the ovaries, uterus and oviducts. Also, PCBs could produce epigenetic effects and be transferred to the offspring through the maternal placenta, causing development retardation, malformation and death of embryos, and damage to organs of multiple generations. Furthermore, the mechanisms of PCBs-induced female reproductive toxicity mainly include receptor-mediated hormone disorders, oxidative stress, apoptosis, autophagy, and epigenetic modifications. Finally, we also present some directions for future research on the reproductive toxicity of PCBs. This detailed information provided a valuable reference for fully understanding the reproductive toxicity of PCBs.

Polychlorinated Biphenyls (PCBs) in the Environment: Occupational and Exposure Events, Effects on Human Health and Fertility

In the last decade or so, polychlorinated biphenyls (PCBs) garnered renewed attention in the scientific community due to new evidence pointing at their continued presence in the environment and workplaces and the potential human risks related to their presence. PCBs move from the environment to humans through different routes; the dominant pathway is the ingestion of contaminated foods (fish, seafood and dairy products), followed by inhalation (both indoor and outdoor air), and, to a lesser extent, dust ingestion and dermal contact. Numerous studies reported the environmental and occupational exposure to these pollutants, deriving from building materials (flame-retardants, plasticizers, paints, caulking compounds, sealants, fluorescent light ballasts, etc.) and electrical equipment. The highest PCBs contaminations were detected in e-waste recycling sites, suggesting the need for the implementation of remediation strategies of such polluted areas to safeguard the health of workers and local populations. Furthermore, a significant correlation between PCB exposure and increased blood PCB concentrations was observed in people working in PCB-contaminated workplaces. Several epidemiological studies suggest that environmental and occupational exposure to high concentrations of PCBs is associated with different health outcomes, such as neuropsychological and neurobehavioral deficits, dementia, immune system dysfunctions, cardiovascular diseases and cancer. In addition, recent studies indicate that PCBs bioaccumulation can reduce fertility, with harmful effects on the reproductive system that can be passed to offspring. In the near future, further studies are needed to assess the real effects of PCBs exposure at low concentrations for prolonged exposure in workplaces and specific indoor environments.

TFEB ameliorates autophagy flux disturbance induced by PBDE-47 via up-regulating autophagy-lysosome fusion

2,2',4,4'-tetrabromodiphenyl ether (PBDE-47), the widely used brominated flame retardant, has remarkable neurotoxicity which is associated with autophagy disorder. However, the mechanism remains unclear. The results showed that PBDE-47 damaged lysosomal biogenesis and interfered with autophagy-lysosome fusion both in vivo and in vitro. Our investigation further demonstrated that PBDE-47 could downregulate TFEB expression and inhibit the nuclear translocation of TFEB. Knockdown of TFEB in PC12 cells increased the reduction of lysosomal-associated proteins and the expression of STX17-SNAP29-VAMP8 proteins involved in autophagy-lysosomal fusion. Conversely, Overexpression TFEB in vitro significantly improved lysosomal abundance and ameliorated the autophagosome-lysosome fusion inhibition, thus restoring autophagic flux and improving PC12 cells survival. In addition, TFEB biologically interacted with STX17 by not inducing or inducing TFEB overexpression. Collectively, our results indicate that the autophagy flux compromised by PBDE-47 is related to the defective fusion of autophagosome and lysosome. TFEB may serve as a promising molecular target for future study of PBDE-47 developmental neurotoxicity.

Environmental contamination and human exposure of polychlorinated biphenyls (PCBs) in China: A review

Polychlorinated biphenyls (PCBs), together with 11 other organic compounds, were initially listed as persistent organic pollutants (POPs) by the Stockholm Convention because of their potential threat to ecosystems and humans. In China, many monitoring studies have been undertaken to reveal the level of PCBs in environment since 2005 due to the introduced stricter environmental regulations. However, there are still significant gaps in understanding the overall spatial and temporal distributions of PCBs in China. This review systematically discusses the occurrence and distribution of PCBs in environmental matrices, organisms, and humans in China. Results showed that PCB contamination in northern and southern China was not significantly different, but the PCB levels in East China were commonly higher than those in West China, which might have been due to the widespread consumption of PCBs and intensive human activities in East China. Serious PCB contamination was found in e-waste disassembling areas (e.g., Taizhou of Zhejiang Province and Qingyuan and Guiyu of Guangdong Province). Higher PCB concentrations were also chronicled in megalopolises and industrial clusters. The unintentionally produced PCBs (UP-PCBs) formed during industrial thermal processes may play an increasingly significant role in PCB pollution in China. Low PCB levels were recorded in rural and underdeveloped districts, particularly in remote and high-altitude localities such as the Tibetan Plateau and the South China Sea. However, these data are limited. Human exposure to PCBs is closely related to the characteristics of environmental pollution. This review also discusses existing issues and future research prospects on PCBs in China. For instance, the accumulation characteristics and migration regularities of PCBs in food webs should be further studied. More investigations should be undertaken to assess the quantitative relationship between external and internal exposure to PCBs. For example, bioaccessibility and bioavailability studies should be supplemented to evaluate human health risks more accurately.

Polychlorinated biphenyls (PCBs) in the colostrum samples from the Yangtze River Region: Exposure profile and risk assessment

Polychlorinated biphenyls (PCBs) may transfer into the neonates through the placental transfer and via breastfeeding after the delivery, thus might be harmful to the infant. Sixty colostrum samples in the Yangtze River Region were collected to investigate the concentration, distribution pattern, and enantiomer characteristic of the PCB exposure. Among all samples, over 90% of pollutants were tetra-to hepta-chlorinated PCBs. The sum concentration of the PCB was 512 (IQR: 322-856) ng g^-1 lipid weight. Enantiomer fraction (EF) of PCB 95 and PCB 149 was found lower than the racemic value, while EFs of PCB 45 and PCB 136 were found higher and near-racemic state, respectively. The concentration pattern and enantiomeric properties of the PCBs indicated that the mothers from Mianyang had a recent exposure to PCBs. Among all samples, similar exposure and metabolic pathways of the PCB congeners were observed. PCB exposure showed no significant correlation with the birth outcome of the infants, but 43.3% of the infants have potential health risks via breastfeeding.

Effects of Polychlorinated Biphenyls on Animal Reproductive Systems and Epigenetic Modifications

Polychlorinated biphenyls (PCBs) are a group of highly toxic endocrine-disrupting chemicals comprising 209 homologs. PCBs are extensively found in the environment and can induce typical estrogenic and profound, long-lasting effects on animals. In this article, the introduction of PCB residues into the environment and the pathways of PCB enrichment in animals are described. PCBs are widely deposited and eventually accumulate in human tissues and body fluids through biomagnification. PCBs can significantly decrease animal fertility and interfere with endocrine processes, leading to the development of various diseases and even cancer. The effects of PCBs on the reproductive systems of animals can also be passed to their offspring, indicating that PCBs may affect the epigenetic modification process. There is currently no treatment to effectively inhibit the toxicity of PCBs in organisms; therefore, the severity of PCB toxicity needs to be widely recognized.

Exploring reproductive associations of serum polybrominated diphenyl ether and hydroxylated brominated diphenyl ether concentrations among women undergoing in vitro fertilization

STUDY QUESTION

Are serum concentrations of polybrominated diphenyl ethers (PBDEs) and hydroxylated brominated diphenyl ethers (OH-BDEs) associated with IVF endpoints?

SUMMARY ANSWER

Positive associations were observed for BDE153 and several OH-BDEs with IVF endpoints.

WHAT IS KNOWN ALREADY

PBDEs have been voluntarily phased out of production in the USA and EU due to their persistence and toxicity to humans and ecosystems. PBDEs have been associated with implantation failure among women undergoing IVF, yet some animal studies suggest greater toxicity from their metabolites, OH-BDEs.

STUDY DESIGN, SIZE, DURATION

We evaluated a subset of 215 women (contributing 330 IVF cycles) enrolled between 2005 and 2016 in a longitudinal cohort based at Massachusetts General Hospital Fertility Center.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The following PBDEs were quantified: 47, 99, 100, 153 and 154 and the following OH-BDEs: 3-OH-BDE47, 5-OH-BDE47, 6-OH-BDE47 and 4-OH-BDE49. Clinical endpoints of IVF treatments were abstracted from electronic medical records. Associations of log-transformed PBDEs and OH-BDEs with IVF outcomes were assessed using multivariable generalized mixed models and cluster weighted generalized estimating equation models adjusted for lipids, age, BMI, race, year of sample collection, IVF protocol and FSH levels. Outcomes were adjusted to represent a percent change in outcome with an increase equal to the magnitude of the difference between the 75th and 25th percentiles for each specific compound (interquartile range (IQR) increase).

MAIN RESULTS AND THE ROLE OF CHANCE

Detection frequencies were highest for congeners 47 and 153 (82% ≥ method detection limit (MDL)) and metabolites 3 and 5-OH-BDE47 and 4-OH-BDE49 (92% > MDL). PBDE and OH-BDE geometric mean concentrations declined by up to 80% between participants recruited in 2005 and those recruited in 2016. An IQR increase of BDE153 was associated with an increase in the probability of implantation (relative risk (RR) = 1.26, 95% CI: 1.16, 1.36), clinical pregnancy (RR = 1.32, 95% CI: 1.19, 1.46) and live birth (RR = 1.34; 95% CI: 1.15, 1.54). An IQR increase in 3 and 5-OH-BDE47 was associated with increased probabilities of implantation (RR = 1.52; 95% CI: 1.11, 2.09), clinical pregnancy (RR = 1.66; 95% CI: 1.17, 2.36), and live birth (RR = 1.61; 95% CI: 1.07, 2.40). When models were stratified by race (White (86%)/Other race (14%)), associations remained positive for White women, yet inverse associations were observed for Other race women. An IQR increase in BDE47 was associated with a 46% decreased probability of clinical pregnancy (95% CI: 0.31, 0.95) for Other race women.

LIMITATIONS, REASONS FOR CAUTION

Despite the long half-lives of PBDEs and OH-BDEs, exposure misclassification is possible for women who underwent multiple treatment cycles over several months or years. It is also possible another medium, such as follicular fluid would be optimal to characterize exposure. We also tested associations for multiple congeners and metabolites with multiple outcomes.

WIDER IMPLICATIONS OF THE FINDINGS

Detections of serum concentrations of PBDEs and OH-BDEs were highest in the early years of the study and suggests that the phase-out of these compounds has contributed to a decrease in exposure. The negative associations found for PBDEs and IVF outcomes among other race women suggests the potential for racial disparity. Potential racial disparities in PBDE exposure and exploration of alternative flame retardants with reproductive health outcomes should be the focus of future investigations.

STUDY FUNDING/COMPETING INTEREST(S)

Funding for this research was supported by the National Institutes of Environmental Health Sciences (NIEHS) [R01 ES009718, ES022955, ES000002 and 009718T32ES007069]. The authors have no conflicts of interest.

Polybrominated Diphenyl Ethers in Human Follicular Fluid Dysregulate Mural and Cumulus Granulosa Cell Gene Expression

Polybrominated diphenyl ethers (PBDEs), a major class of flame retardants incorporated into numerous consumer products, leach out into dust resulting in widespread exposure. There is evidence from in vitro and in vivo animal studies that PBDEs affect ovarian granulosa cell function and follicular development, yet human studies of their association with female infertility are inconclusive. Here, we tested the hypothesis that exposure to the PBDEs in follicular fluid is associated with dysregulation of gene expression in the mural and cumulus granulosa cells collected from women undergoing in vitro fertilization by intracytoplasmic sperm injection. The median concentration of the ∑ 10PBDEs detected in the follicular fluid samples (n = 37) was 15.04 pg/g wet weight. RNA microarray analyses revealed that many genes were differentially expressed in mural and cumulus granulosa cells. Highest vs lowest quartile exposure to the Σ 10PBDEs or to 2 predominant PBDE congeners, BDE-47 or BDE-153, was associated with significant effects on gene expression in both cell types. Mural granulosa cells were generally more sensitive to PBDE exposure compared to cumulus cells. Overall, gene expression changes associated with BDE-47 exposure were similar to those for ∑ 10PBDEs but distinct from those associated with BDE-153 exposure. Interestingly, exposure to BDE-47 and ∑ 10PBDEs activated the expression of genes in pathways that are important in innate immunity and inflammation. To the best of our knowledge, this is the first demonstration that exposure to these environmental chemicals is associated with the dysregulation of pathways that play an essential role in ovulation.

The effects of three different microplastics on enzyme activities and microbial communities in soil

Soils always receive microplastics (MPs) from plastic mulching, compost, and sewage irrigation, but the effects of MPs on soil environment remain largely unexplored. The objectives of this study were to investigate the effects of three MPs (membranous polyethylene (PE), fibrous polypropylene (PP), and microsphere PP) on enzyme activities and microbial community structure in one loamy and sandy soil. The concentration of microsphere PP (2 mg/g) was one-tenth of those of the other two MPs (20 mg/g). The results showed that the effects of three MPs on urease, dehydrogenase, and alkaline phosphatase activities followed the order: fibrous PP > membranous PE > microsphere PP, membranous PE > microsphere PP > fibrous PP and fibrous PP > microsphere PP > membranous PE, respectively. Results from high-throughput sequencing of 16S rRNA revealed that the membranous PE and fibrous PP raised the alpha diversities of the soil microbiota, whereas the diversity indexes of microbiota on MPs surfaces were significantly lower than those in the amended soils. MPs significantly altered the microbial community structure, especially for the enrichment of Acidobacteria and Bacteroidetes, the depletion of Deinococcus-Thermus and Chloroflexi. Aeromicrobium, Streptomyces, Mycobacterium, Janibacter, Nocardia, Arthrobacter were prone to inhabit on the MPs surfaces. PRACTITIONER POINTS: Three microplastics had different effects on soil enzyme activities. Fibrous PP had a more persistent effect on microbial activity. Membranous PE and fibrous PP raised the alpha diversities of soil microbiota. The effects of membranous PE and fibrous PP on microbial communities were similar. Distinct microbial communities were enriched on the surfaces of microplastics.

Temporal trends of "old" and "new" persistent halogenated organic pollutants in fish from the third largest freshwater lake in China during 2011-2018 and the associated health risks

The study aimed to investigate temporal trends of "old" and "new" persistent halogenated organic pollutants (HOPs) in Taihu Lake, the third largest freshwater lake in China, and the associated health risks. Five fish species were consecutively collected from the lake every year during 2011-2018. HOPs including 37 polychlorinated biphenyls (PCBs), 10 organochlorine pesticides (OCPs), short- and medium-chain chlorinated paraffins (SCCPs and MCCPs), 19 polybrominated diphenyl ethers (PBDEs), and 10 new brominated flame retardants (NBFRs), were measured. The results showed that all the HOPs were detected, with MCCPs and NBFRs showing the highest and lowest concentrations, respectively. The levels of SCCPs and MCCPs were several orders of magnitude higher than those of the other HOPs. There were obvious increasing trends for SCCPs, MCCPs, and hexachlorobenzene, but a decreasing trend for PBDEs. No obvious increasing or decreasing trends were observed for the other HOPs. The present study indicated that the use of NBFRs to replace PBDEs was not yet clearly observed. Fish consumption did not result in non-carcinogenic risks, but posed low carcinogenic risks, with PCBs and DDTs being the highest-risk contaminants because of historical residues. This is the first study for the temporal variations of the HOPs in the lake.

Effects of intrauterine exposure to 2,3',4,4',5-pentachlorobiphenyl on the reproductive system and sperm epigenetic imprinting of male offspring

Polychlorinated biphenyls (PCBs) are a class of persistent organic environmental pollutants with a total of 209 homologs. The homolog 2,3',4,4',5-pentachlorobiphenyl (PCB118) is one of the most important dioxin-like PCBs and is highly toxic. PCB118 can accumulate in human tissues, serum and breast milk, which leads to direct exposure of the fetus during development. In the present study, pregnant mice were exposed to 0, 20 and 100 μg/kg/day of PCB118 during the stage of fetal primordial germ cell migration. Compared with the control group, we found morphological alterations of the seminiferous tubules and a higher sperm deformity rate in the male offspring in the treatment groups. Furthermore, the methylation patterns in the treatment groups of the imprinted genes H19 and Gtl2 in the sperm were altered in the male offspring. We also characterized the disturbance of the expression levels of DNA methyltransferase 1 (Dnmt1), Dnmt3a, Dnmt3b, Dnmt3l, and Uhrf1. The results indicated that intrauterine exposure to low doses of PCB118 could significantly damage the reproductive health of the male offspring. Therefore, attention should be paid to the adverse effects of PCB118 exposure during pregnancy on the reproductive system of male offspring.

Levels and congener profiles of halogenated persistent organic pollutants in human serum and semen at an e-waste area in South China

Typical halogenated persistent organic pollutants (Hal-POPs), including polybrominated diphenyl ethers (PBDEs), polybrominated biphenyls (PBBs), polychlorinated biphenyls (PCBs), and dichlorodiphenyltrichloroethane (DDT), are a group of ubiquitous organic pollutants with an endocrine disrupting effect. This study evaluated the accumulation and congener profiles of Hal-POPs in the bodies of men who live/work in areas of South China where electronic wastes are collected and managed, especially in their semen samples. The results show that the detection frequency and serum concentrations of Hal-POP congeners within the high-exposure group (HEG) were higher than those of the low-exposure group (LEG). Furthermore, an identical trend was observed for the seminal plasma concentrations of Hal-POPs. The distribution characteristics, such as their mean, median, and discrete values, of PBDE congeners in serum and semen samples from the same subjects were consistent with each other. However, the distribution characteristics of PCB congeners in serum samples were different from those in semen samples. BDE153 was one of the most abundant congeners found in the serum and semen samples; hence, it can be identified as an indicator PBDE congener. Further research is needed to explore the mechanism of Hal-POPs distribution in human semen and serum samples.

Persistent environmental endocrine-disrupting chemicals in ovarian follicular fluid and in vitro fertilization treatment outcome in women

Several international organizations have recently highlighted endocrine-disrupting chemicals (EDCs) as factors of concern in human reproduction. Since successful reproduction is dependent on timely and appropriate action of hormones, disruption of the endocrine system could lead to difficulties in conceiving or carrying a pregnancy to term. EDCs are chemicals that disrupt the endocrine system by activating or inhibiting receptors of the endocrine system, and/or altering hormone receptor expression; signal transduction; epigenetic marks; hormone synthesis, transport, distribution, and metabolism; and the fate of hormone-producing cells. Due to the increasing production of industrial chemicals over the past century and their lenient control, EDCs are now common contaminants in the environment. Consequently, everyone faces a life-long exposure to mixtures of chemicals, some of which have been identified as EDCs. As birth rates in humans are declining and the use of assisted reproductive technologies increasing, it is timely to consider possible effects of EDCs on human reproduction and fertility. In this review, we focus on persistent EDCs, their occurrence in ovarian follicular fluid, and associations to treatment outcomes in assisted reproduction. Our summary shows that despite being banned decades ago, mixtures of persistent EDCs are still detected in the ovarian follicular fluid, demonstrating direct exposure of oocytes to these chemicals. In addition, there are several reported associations between exposure and worse outcome in in vitro fertilization. Further research is therefore warranted to prove causality, which will lead towards better regulation and exposure reduction.

Effects of 2,3',4,4'5-pentachlorobiphenyl exposure during pregnancy on epigenetic imprinting and maturation of offspring's oocytes in mice

Polychlorinated biphenyls (PCBs) are a class of organic pollutants that have been widely found in the environment. The chemical 2,3',4,4'5-pentachlorobiphenyl (PCB118) is an important dioxin-like PCB compound with strong toxicity. PCB118 can accumulate in adipose tissue, serum and milk in mammals, and it is highly enriched in the follicular fluid. In this study, pregnant mice were exposed to 0, 20 and 100 μg/kg/day of PCB118 during pregnancy at the fetal primordial germ cell migration stage. The methylation patterns of the imprinted genes H19, Snrpn, Peg3 and Igf2r as well as the expression levels of Dnmt1, 3a, 3b and 3l, Uhrf1, Tet2 and Tet3 in fully grown germinal vesicle oocytes were measured in offspring. The rates of in vitro maturation, in vitro fertilization, oocyte spindle and chromosomal abnormalities were also calculated. The results showed that prenatal exposure to PCB118 altered the DNA methylation status of differentially methylated regions in some imprinted genes, and the expression levels of Dnmt1, 3a, and 3l, Uhrf1 and Tet3 were also changed. In addition, PCB118 disturbed the maturation process of progeny mouse oocytes in a dose-dependent manner. Therefore, attention should be paid to the potential impacts of PCB118-contaminated dietary intake during pregnancy on the offspring's reproductive health.