Hydroxylated PAHs alter the synthesis of androgens and estrogens in subcellular fractions of carp gonads

Association between polycyclic aromatic hydrocarbons and infertility in U.S. women: National Health and Nutrition Examination Survey 2013-2016

Although there is a body of research indicating the potential impact of polycyclic aromatic hydrocarbons (PAHs) exposure on male infertility, the understanding of how PAH might affect female infertility is still limited. This study aimed to evaluate associations of PAHs, both individually and as a mixture, with female infertility using multiple logistic regression, Bayesian kernel machine regression (BKMR), and quantile g-computation (QGC) models based on data from the National Health and Nutrition Examination Survey (NHANES) 2013-2016. The study included 729 female participants. Multiple logistic regression results indicated that there was a significant association between the third tertile of 2-hydroxy fluorene (2-OHFLU) and female infertility, and the OR was 2.84 (95% CI: 1.24-6.53, P value = 0.015) compared with the first tertile after adjusting for the potential covariates. The BKMR model revealed a positive overall trend between mixed PAH exposure and female infertility, particularly when the mixture was at or above the 55th percentile, where 2-hydroxynaphthalene (2-OHNAP) and 1-hydroxypyrene (1-OHPYR) were the primary influences of the mixture. The univariate exposure-response function indicated positive associations between individual PAH exposure, specifically 2-OHNAP, 2-OHFLU, and 1-OHPYR, and female infertility. The QGC model also indicated a positive trend between exposure to a mixture of PAHs and female infertility, although it did not reach statistical significance (OR = 1.33, 95%CI: 0.86-2.07), with 1-OHPYR having the greatest positive effect on the outcome. This study suggested that exposure to PAHs may be associated with female infertility and further research is needed to consolidate and confirm these findings.

The effects of polycyclic aromatic compounds (PACs) on mammalian ovarian function

•

Toxicity of polycyclic aromatic compounds (PACs) is limited to a subset of PACs.

•

Exposure to these compounds impact major processes necessary for ovarian function.

•

PAC exposure causes follicle loss and aberrant steroid production and angiogenesis.

•

PAC exposure may increase the risk for impaired fertility and ovarian pathologies.

•

The study of PACs as ovarian toxicants should include additional compounds.

Polycyclic aromatic compounds (PACs) are a broad class of contaminants ubiquitously present in the environment due to natural and anthropogenic activities. With increasing industrialization and reliance on petroleum worldwide, PACs are increasingly being detected in different environmental compartments. Previous studies have shown that PACs possess endocrine disruptive properties as these compounds often interfere with hormone signaling and function. In females, the ovary is largely responsible for regulating reproductive and endocrine function and thus, serves as a primary target for PAC-mediated toxicity. Perturbations in the signaling pathways that mediate ovarian folliculogenesis, steroidogenesis and angiogenesis can lead to adverse reproductive outcomes including polycystic ovary syndrome, premature ovarian insufficiency, and infertility. To date, the impact of PACs on ovarian function has focused predominantly on polycyclic aromatic hydrocarbons like benzo(a)pyrene, 3-methylcholanthrene and 7,12-dimethylbenz[a]anthracene. However, investigation into the impact of substituted PACs including halogenated, heterocyclic, and alkylated PACs on mammalian reproduction has been largely overlooked despite the fact that these compounds are found in higher abundance in free-ranging wildlife. This review aims to discuss current literature on the effects of PACs on the ovary in mammals, with a particular focus on folliculogenesis, steroidogenesis and angiogenesis, which are key processes necessary for proper ovarian functions.

Levels, source appointment, and ecological risk of petroleum hydrocarbons in tropical coastal ecosystems (northeast Brazil): Baseline for future monitoring programmes of an oil spill area

We reviewed 20 years of levels, sources, and environmental risks related to the main petroleum hydrocarbons in the northeast region of Brazil. The aim of this study was to conduct a systematic review to serve as a comprehensive baseline for future monitoring programmes related to the oil spill disaster in 2019/2020. Most contamination levels of both PAHs and AHs were classified as low, except those in specific areas influenced by human activities, such as ports, highly urbanised mangroves, or rivers of medium-sized cities with inadequate liquid and solid waste treatment. Most hydrocarbons were linked to natural sources and burning processes, except in regions of extraction activities and petrochemical facilities as well as highly urbanised areas, where degraded petroleum and oil hydrocarbons predominated. Only 2.5% of the samples exceeded threshold effect levels for ∑_16-PAHs and no samples exceeded probable effect levels. When regional threshold levels were used, however, the probable effect for the ∑_16-PAHs measured was high, ranging from 5.8 to 6.1%. The few studies reporting biological responses showed that hydrocarbons from anthropogenic sources can induce adverse effects on marine organisms even at low to moderate levels. As the region has recently received a considerable quantity of crude oil, studies should be prioritised for a more precise assessment of the impact of this oil spill.

Damages to biological macromolecules in gonadal subcellular fractions of scallop Chlamys farreri following benzo[a]pyrene exposure: Contribution to inhibiting gonadal development and reducing fertility

Benzo[a]pyrene (B[a]P), a representative polycyclic aromatic hydrocarbon (PAH) compound in marine ecosystem, has great potential for chronic toxicity to marine animals. It is becoming increasingly apparent that reproductive system is the major target of B[a]P, but the adverse effects of B[a]P on subcellular fractions in bivalve gonads have not been elucidated. Scallops Chlamys farreri are used as the experimental species since they are sensitive to environmental pollutants. This study was conducted to investigate how B[a]P affected the gonadal subcellular fractions, including plasma membrane, nucleus, mitochondria and microsome in scallops, and whether subcellular damages were related to reproductive toxicity. The results showed that mature gametes' counts were significantly decreased in B[a]P-treated scallops. Three biological macromolecules (viz., DNA, lipids and proteins) in gonadal subcellular fractions obtained by differential centrifugation suffered damages, including DNA damage, lipid peroxidation and protein carbonylation in B[a]P treatment groups. Interestingly, mitochondria and microsome were more vulnerable to lipid peroxidation and protein carbonylation than plasma membrane and nucleus, meanwhile males were more susceptible to DNA damage than females under B[a]P exposure. In addition, histological analysis showed that B[a]P delayed gonadal development in C. farreri. To summarize, our results indicated that B[a]P caused damages to biological macromolecules in gonadal subcellular fractions and then induced damages to gonadal tissues of C. farreri, which further inhibited gonadal development and ultimately leaded to reduction in fertility. This study firstly reports the impacts of PAHs on subcellular fractions in bivalves and their relationship with reproductive toxicity. Moreover, exposure of reproductive scallops to B[a]P leads to defects in reproduction, raising concerns on the possible long-term consequences of PAHs for natural populations of bivalves.

Untangling mechanisms of crude oil toxicity: Linking gene expression, morphology and PAHs at two developmental stages in a cold-water fish

Early life stages of fish are highly sensitive to crude oil exposure and thus, short term exposures during critical developmental periods could have detrimental consequences for juvenile survival. Here we administered crude oil to Atlantic haddock (Melanogrammus aeglefinus) in short term (3-day) exposures at two developmental time periods: before first heartbeat, from gastrulation to cardiac cone stage (early), and from first heartbeat to one day before hatching (late). A frequent sampling regime enabled us to determine immediate PAH uptake, metabolite formation and gene expression changes. In general, the embryotoxic consequences of an oil exposure were more severe in the early exposure animals. Oil droplets on the eggshell resulted in severe cardiac and craniofacial abnormalities in the highest treatments. Gene expression changes of Cytochrome 1 a, b, c and d (cyp1a, b, c, d), Bone morphogenetic protein 10 (bmp10), ABC transporter b1 (abcb1) and Rh-associated G-protein (rhag) were linked to PAH uptake, occurrence of metabolites of phenanthrene and developmental and functional abnormalities. We detected circulation-independent, oil-induced gene expression changes and separated phenotypes linked to proliferation, growth and disruption of formation events at early and late developmental stages. Changes in bmp10 expression suggest a direct oil-induced effect on calcium homeostasis. Localized expression of rhag propose an impact on osmoregulation. Severe eye abnormalities were linked to possible inappropriate overexpression of cyp1b in the eyes. This study gives an increased knowledge about developmentally dependent effects of crude oil toxicity. Thus, our findings provide more knowledge and detail to new and several existing adverse outcome pathways of crude oil toxicity.

Vitellogenin levels and others biomarkers show evidences of endocrine disruption in fish species from Iguaçu River - Southern Brazil

The adverse effects of endocrine disrupting chemicals (EDCs) on aquatic wildlife and human health represent a current issue of high public concern. Even so, they are still poorly studied in aquatic environments of South America. The aim of the present study was to investigate the impact of EDCs in five cascading reservoirs from the Iguaçu River, evaluating reproductive endpoints in three native fish species (Astyanax bifasciatus, Chrenicicla iguassuensis and Geophagus brasiliensis). Additionally, a polyclonal antiserum anti-vitellogenin from G. brasiliensis and a capture ELISA assay were developed for detection of estrogenic or anti-estrogenic activities in male and female fish, respectively. Vitellogenin (VTG) levels in male fish from the Iguacu River was observed, as well as decreased levels of vitellogenin and estradiol in the plasma of female fish. These findings were associated with immature gonads and lower gonadosomatic index in G. brasiliensis adult females from the Foz do Areia (FA) Reservoir. Additionally, both endemic species (Astyanax bifasciatus and Chrenicicla iguassuensis) displayed immature gonads and histological changes, such as degeneration of germ cells, in other studied reservoirs. The current results suggest that these reproductive responses may be associated with the bioavailability of EDCs in the Iguaçu River. These impacts are likely related to chemicals released by human activities, especially from sewage and industrial sources and agricultural production, detected in previous studies. Overall, the FA reservoir was potentially the most affected by chemicals with endocrine properties, and further studies are necessary to identify and quantify these chemicals.

Assessing PAHs pollution in Shandong coastal area (China) by combination of chemical analysis and responses of reproductive toxicity in crab Portunus trituberculatus

The concentrations of PAHs in seawater and sediments were measured at three selected sites (S1, S2, and S3) along the coastal area of Shandong (China) in April, May, and June, 2015, which ranged from 29.72 to 123.88 ng/L and 82.62 to 232.63 ng/g, respectively. Meanwhile, the reproductive toxicity responses in crab Portunus trituberculatus were also evaluated to assess the pollution of PAHs during the sampling period. Chemical analysis showed that S3 was the most PAH-contaminated area while S1 was the least, and the biochemical parameters concerned with reproduction were efficiently responded to the three sites, especially in S3 (p < 0.05). Moreover, the principal component analyses (PCA) showed that parameters for DNA alkaline unwinding, protein carbonyl content, and lipid peroxidation levels in two genders, 17β-estradiol in female, testosterone and TESK2 gene expression in male crabs, were closely correlated with the concentrations of PAHs (2 + 3 rings, 4 rings, and 5 + 6 rings), which were considered to be good candidate indicators to assess the environmental pollutions resulting from PAHs in the coastal area of Shandong, China.

Associations between urinary biomarkers of polycyclic aromatic hydrocarbon exposure and reproductive function during menstrual cycles in women

Essentially all women are exposed to polycyclic aromatic hydrocarbons (PAHs), formed during incomplete combustion of organic materials, including fossil fuels, wood, foods, and tobacco. PAHs are ovarian toxicants in rodents, and cigarette smoking is associated with reproductive abnormalities in women. Biomonitoring of hydroxylated PAH (OH-PAH) metabolites in urine provides an integrated measure of exposure to PAHs via multiple routes and has been used to characterize exposure to PAHs in humans. We hypothesized that concentrations of OH-PAHs in urine are associated with reproductive function in women. We recruited women 18-44years old, living in Orange County, California to conduct daily measurement of urinary luteinizing hormone (LH) and estrone 3-glucuronide (E₁3G) using a microelectronic fertility monitor for multiple menstrual cycles; these data were used to calculate endocrine endpoints. Participants also collected urine samples on cycle day 10 for measurement of nine OH-PAHs. Models were constructed for eight endpoints using a Bayesian mixed modeling approach with subject-specific random effects allowing each participant to act as a baseline for her set of measurements. We observed associations between individual OH-PAH concentrations and follicular phase length, follicular phase LH and E₁3G concentrations, preovulatory LH surge concentrations, and periovulatory E₁3G slope and concentration. We have demonstrated the feasibility of using urinary reproductive hormone data obtained via fertility monitors to calculate endocrine endpoints for epidemiological studies of ovarian function during multiple menstrual cycles. The results show that environmental exposure to PAHs is associated with changes in endocrine markers of ovarian function in women in a PAH-specific manner.

Assessment of the environmental quality of coastal sediments by using a combination of in vitro bioassays

The environmental quality of marine sediments collected in the area of influence of the Po and Danube Rivers was assessed by using a battery of bioassays based on the use of PLHC-1 cells, zebrafish-Pxr-transfected COS-7 cells, and sea bass ovarian subcellular fractions. This allowed the determination of multiple endpoints, namely, cytotoxicity, oxidative stress, induction of CYP1A, activation of zebrafish Pxr and inhibition of ovarian aromatase. Organic extracts of sediments influenced by the Danube River and collected near harbors and urban discharges showed significant cytotoxicity, CYP1A induction and inhibition of aromatase activity. An analogous response of CYP1A induction and zfPxr activation was observed, which suggests the existence of common ligands of AhR and PXR in the sediment extracts. The study highlights the usefulness of the selected bioassays to identify those sediments that could pose a risk to aquatic organisms and that require further action in order to improve their environmental quality.

The applied indicators of water quality may underestimate the risk of chemical exposure to human population in reservoirs utilized for human supply-Southern Brazil

The knowledge concerning associations between chronic chemical exposure and many disorders with complex etiology involving gene-environment interactions is increasing, and new methods must be developed to improve water quality monitoring. The complexity of chemical mixtures in polluted aquatic environments makes the evaluation of toxic potential in those sites difficult, but the use of biomarkers and bioindicators has been recognized as a reliable tool to assess risk of exposure to biota and also the human population. In order to evaluate the use of fish and biomarkers to assess toxic potential and bioavailability of chemicals in human-related hydric resources, an in situ experiment was accomplished in two water reservoirs designated for human supply, which were previously evaluated by the local environmental regulatory agency through a set of physical, chemical, and classical biological parameters. Molecular, biochemical, and morphological biomarkers were performed in caged Oreochromis niloticus kept for 6 months in the studied reservoirs to assess potentially useful biomarkers to evaluate the quality of water for human supply. Chemical analysis of toxic metals in liver and muscle and polycyclic aromatic hydrocarbons (PAHs) in bile was considered to assess the bioavailability of pollutants and highlight human activity impact. The reservoir previously classified by a governmental agency as less impacted presented more risk of exposure to biota. These results were supported by chemical analysis, vitellogenin expression, histopathological findings (gonads, liver, and gills), as well as indicators of neurotoxic effects and oxidative stress in liver. The inclusion of some biomarkers as parameters in regulatory monitoring programs in reservoirs designated for human supply is strongly suggested to evaluate the risks of exposure to the human population. Thus, a revision of the traditional biological and physicochemical analysis utilized to establish the conditions of water quality is necessary.

Ecological relevance of biomarkers in monitoring studies of macro-invertebrates and fish in Mediterranean rivers

Mediterranean rivers are probably one of the most singular and endangered ecosystems worldwide due to the presence of many endemic species and a long history of anthropogenic impacts. Besides a conservation value per se, biodiversity is related to the services that ecosystems provide to society and the ability of these to cope with stressors, including climate change. Using macro-invertebrates and fish as sentinel organisms, this overview presents a synthesis of the state of the art in the application of biomarkers (stress and enzymatic responses, endocrine disruptors, trophic tracers, energy and bile metabolites, genotoxic indicators, histopathological and behavioural alterations, and genetic and cutting edge omic markers) to determine the causes and effects of anthropogenic stressors on the biodiversity of European Mediterranean rivers. We also discuss how a careful selection of sentinel species according to their ecological traits and the food-web structure of Mediterranean rivers could increase the ecological relevance of biomarker responses. Further, we provide suggestions to better harmonise ecological realism with experimental design in biomarker studies, including statistical analyses, which may also deliver a more comprehensible message to managers and policy makers. By keeping on the safe side the health status of populations of multiple-species in a community, we advocate to increase the resilience of fluvial ecosystems to face present and forecasted stressors. In conclusion, this review provides evidence that multi-biomarker approaches detect early signs of impairment in populations, and supports their incorporation in the standardised procedures of the Water Frame Work Directive to better appraise the status of European water bodies.

Association of serum levels of typical organic pollutants with polycystic ovary syndrome (PCOS): a case-control study

STUDY QUESTION

Is polycystic ovary syndrome (PCOS) associated with increased serum levels of typical organic pollutants?

SUMMARY ANSWER

PCOS in Han females from Northern China was significantly associated with elevated serum levels of pollutants, including polychlorinated biphenyls (PCBs), organochlorine pesticides and polycyclic aromatic hydrocarbons (PAHs).

WHAT IS KNOWN ALREADY

PCOS is arguably the most common endocrinopathy in females of reproductive age. The etiology of PCOS is thought to be multifactorial.

STUDY DESIGN, SIZE, DURATION

This was a preliminary case-control study undertaken at the Division of Reproductive Center, Peking University Third Hospital. Fifty participants affected by PCOS and 30 normal controls were recruited between August and October 2012 from Northern China. All participants were Han women.

PARTICIPANTS/MATERIALS, SETTING, METHODS

PCOS participants were diagnosed according to the 2003 Rotterdam criteria. The control participants were non-pregnant females unable to conceive solely due to male azoospermia. Serum levels of a wide range of organic pollutants, including PCBs, organochlorine pesticides, PAHs and more than 20 phenolic pollutants, were analyzed using gas chromatographic mass spectrometry.

MAIN RESULTS AND THE ROLE OF CHANCE

Serum levels of PCBs, pesticides and PAHs were significantly higher in the PCOS group than the control group. Concentrations of PCBs, p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) and PAHs in serum above median levels were associated with PCOS with odds ratios of 3.81 [95% confidence interval (CI), 1.45-10.0], 4.89 (95% CI, 1.81-13.2) and 2.39 (95% CI, 0.94-6.05), respectively. Partial least-squares-discriminant analysis (PLS-DA) confirmed that serum levels of organic pollutants were associated with PCOS, especially for p,p'-DDE and PCBs.

LIMITATIONS, REASONS FOR CAUTION

Some other possible covariates (e.g. dietary and income) were missed in this study, although education and occupation have been considered as an indicator of personal income. The PLS-DA model allowed a quasi-exposome analysis with over 60 kinds of typical organic pollutants; however, the possibility of other pollutants involved in the PCOS still could not be excluded.

WIDER IMPLICATIONS OF THE FINDINGS

Our study identified that bodily retention of environmental organic pollutants-including PCBs, pesticides (especially p,p'-DDE) and PAHs-was associated with PCOS.

STUDY FUNDING/COMPETING INTERESTS

This research was supported by the Ministry of Science and Technology of China Grants (973 program; 2014CB943203 and 2015CB553401), National Natural Science Foundation of China (21322705, 21190051, 41121004 and 81170538), National Key Technology R&D Program in the Twelve Five-Year Plan (2012BAI32B01) and the Collaborative Innovation Center for Regional Environmental Quality. There are no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

None. This is not a clinical trial.

The in vitro interference of synthetic progestogens with carp steroidogenic enzymes

Synthetic progestogens represent a class of pharmaceuticals widely used in oral contraceptives and in hormone replacement therapies. They reach the aquatic environment through wastewater effluents; however, environmental concentrations and effects on non-target organisms are poorly known. Given the important role of progestogens regulating fish spawning processes, this study aimed at assessing the in vitro interference of four currently used progestogens-drospirenone (DRO), levonorgestrel (LNG), norethindrone (NOR) and cyproterone acetate (CPA) - with key enzymatic activities involved in the synthesis of active steroids in carp (Cyprinus carpio). The enzymatic pathways investigated were (a) CYP17 (C17,20-lyase) and CYP11β involved in the synthesis of androgens, (b) CYP19 that catalyses the aromatization of androgens to estrogens, and (c) 20β-hydroxysteroid dehydrogenase (20β-HSD) responsible for the synthesis of maturation-inducing hormones. All tested progestogens significantly inhibited the synthesis of androgens: DRO (IC50: 3.8 μM) was the strongest inhibitor of CYP17 followed by CPA (IC50s: 183 μM). Moreover, NOR (IC50: 0.4 μM), DRO (IC50: 1.8 μM) and CPA (IC50s: 87 μM) inhibited CYP11β. An inhibition by NOR of ovarian CYP19 activity, and by DRO and CPA of 20β-HSD was also observed, but at rather high concentrations (500 μM). Overall, this study highlights the potential of synthetic progestogens, and particularly DRO and NOR, to interfere with the biosynthesis of androgens in carp gonads.

Characterization of the environmental quality of sediments from two estuarine systems based on different in-vitro bioassays

This study characterizes the environmental quality of sediments from the Arade and Guadiana estuaries using different in-vitro bioassays: a) fish hepatoma cell line (PLHC-1) to determine cytotoxicity and presence of CYP1A and oxidative stress inducing agents; b) gonad subcellular fractions from sea bass (Dicentrarchus labrax) to detect compounds that are likely to act as endocrine disrupters by interfering with the synthesis of androgens (CYP17, CYP11β) and estrogens (CYP19). Approximately 60% of extracts from the Arade estuary were cytotoxic when tested at 60 mg eQsed/mL, while only one sample from Guadiana showed cytotoxicity. Sediments from Arade collected close to harbours and waste water effluents were enriched with CYP1A inducing agents, while those from the upper Guadiana induced oxidative stress in PLHC-1 cells. On the other hand, several extracts from both estuaries were able to significantly inhibit CYP17, CYP11β and CYP19 activities in gonad subcellular fractions of sea bass, which indicates the presence of endocrine disrupters, particularly in several sites from the Arade estuary. Overall, the study highlights the usefulness of in-vitro bioassays to identify those sediments that could pose risk to aquatic organisms and that require further action to improve their environmental quality.

The TRPM4 channel inhibitor 9-phenanthrol

The phenanthrene-derivative 9-phenanthrol is a recently identified inhibitor of the transient receptor potential melastatin (TRPM) 4 channel, a Ca(2+) -activated non-selective cation channel whose mechanism of action remains to be determined. Subsequent studies performed on other ion channels confirm the specificity of the drug for TRPM4. In addition, 9-phenanthrol modulates a variety of physiological processes through TRPM4 current inhibition and thus exerts beneficial effects in several pathological conditions. 9-Phenanthrol modulates smooth muscle contraction in bladder and cerebral arteries, affects spontaneous activity in neurons and in the heart, and reduces lipopolysaccharide-induced cell death. Among promising potential applications, 9-phenanthrol exerts cardioprotective effects against ischaemia-reperfusion injuries and reduces ischaemic stroke injuries. In addition to reviewing the biophysical effects of 9-phenanthrol, here we present information about its appropriate use in physiological studies and possible clinical applications.

Comparative studies of multi-walled carbon nanotubes (MWNTs) and octadecyl (C18) as sorbents in passive sampling devices for biomimetic uptake of polycyclic aromatic hydrocarbons (PAHs) from soils

To avoid overestimating the risk of polycyclic aromatic hydrocarbons (PAHs), research is needed to evaluate the bioavailable portion of PAHs in the environment. However, limited PSDs were developed for a terrestrial soil system. In this study, two sorbents, octadecyl (C18) and multi-walled carbon nanotubes (MWNTs), were individually evaluated as sorbents in passive sampling devices (PSDs) as biomimetic samplers to assess the uptake of PAHs from soil. C18-PSDs were an excellent biomimetic tool for PAHs with a low molecular weight in complex exposure conditions with different soil types, types of PAHs, aging periods, and initial PAH concentrations in soil. The utility of MWNT-PSDs was limited by extraction efficiencies of PAHs from MWNTs. However, when compared to C18-PSDs, they had higher adsorption capacities and were less expensive. This study provides data regarding useful techniques that can be used in risk assessment to assess the bioavailability of PAHs in soil.