The relationship of urinary metabolites of carbaryl/naphthalene and chlorpyrifos with human semen quality

Exploring Prenatal Exposure to Halogenated Compounds and Its Relationship with Birth Outcomes Using Nontarget Analysis

Halogenated organic compounds (HOCs) are a class of contaminants showing high toxicity, low biodegradability, and high bioaccumulation potential, especially chlorinated and brominated HOCs (Cl/Br-HOCs). Knowledge gaps exist on whether novel Cl/Br-HOCs could penetrate the placental barrier and cause adverse birth outcomes. Herein, 326 cord blood samples were collected in a hospital in Jinan, Shandong Province from February 2017 to January 2022, and 44 Cl/Br-HOCs were identified with communicating confidence level above 4 based on a nontarget approach, covering veterinary drugs, pesticides, and their transformation products, pharmaceutical and personal care products, disinfection byproducts, and so on. To our knowledge, the presence of closantel, bromoxynil, 4-hydroxy-2,5,6-trichloroisophthalonitrile, 2,6-dibromo-4-nitrophenol, and related components in cord blood samples was reported for the first time. Both multiple linear regression (MLR) and Bayesian kernel machine regression (BKMR) models were applied to evaluate the relationships of newborn birth outcomes (birth weight, length, and ponderal index) with individual Cl/Br-HOC and Cl/Br-HOCs mixture exposure, respectively. A significantly negative association was observed between pentachlorophenol exposure and newborn birth length, but the significance vanished after the false discovery rate correction. The BKMR analysis showed that Cl/Br-HOCs mixture exposure was significantly associated with reduced newborn birth length, indicating higher risks of fetal growth restriction. Our findings offer an overview of Cl/Br-HOCs exposome during the early life stage and enhance the understanding of its exposure risks.

Endocrine-disrupting chemicals: Mainstream recognition of health effects and implications for the practicing internist

Rapidly advancing evidence documents that a broad array of synthetic chemicals found ubiquitously in the environment contribute to disease and disability across the lifespan. Although the early literature focused on early life exposures, endocrine-disrupting chemicals (EDCs) are now understood to contribute substantially to chronic disease in adulthood, especially metabolic, cardiovascular, and reproductive consequences as well as endocrine cancers. The contribution to mortality is substantial, with over 90,000 deaths annually and at least $39 billion/year in lost economic productivity in the United States (US) due to exposure to certain phthalates that are used as plasticizers in food packaging. Importantly, exposures are disproportionately high in low-income and minoritized populations, driving disparities in these conditions. Though non-Hispanic Blacks and Mexican Americans comprise 12.6% and 13.5% of the US population, they bear 16.5% and 14.6% of the disease burden due to EDCs, respectively. Many of these exposures can be modified through safe and simple behavioral changes supported by proactive government action to both limit known hazardous exposures and to proactively screen new industrial chemicals prior to their use. Routine healthcare maintenance should include guidance to reduce EDC exposures, and a recent report by the Institute of Medicine suggests that testing be conducted, particularly in populations heavily exposed to perfluoroalkyl substances-chemicals used in nonstick coatings as well as oil- and water-resistant clothing.

Endocrine-disrupting chemicals and male reproductive health

Modifiable factors, such as environmental exposures, can impact human fertility. The objective of this review is to summarize the potential effects of exposure to important endocrine-disrupting chemicals on male reproductive health. Most experimental and animal data demonstrate strong evidence for the negative effects of exposure to phenols, phthalates, pesticides, and perfluoroalkyl and polyfluoroalkyl substances on male reproductive health. Although evidence of negative associations in humans was overall strong for phthalates and pesticides, limited and inconclusive relationships were found for the other examined chemical biomarkers. Reasons for the discrepancies in results include but are not limited to, differences in study populations, exposure concentrations, number of samples collected, sample sizes, study design, and residual confounding. Additional studies are needed, particularly for newer phenols and perfluoroalkyl and polyfluoroalkyl substances, given the scarce literature on the topic and increasing exposures over time.

Adult Organophosphate and Carbamate Insecticide Exposure and Sperm Concentration: A Systematic Review and Meta-Analysis of the Epidemiological Evidence

BACKGROUND

Evidence of the negative impacts of contemporary use insecticides on sperm concentration has increased over the last few decades; however, meta-analyses on this topic are rare.

OBJECTIVES

This investigation assessed the qualitative and quantitative strength of epidemiological evidence regarding adult exposure to two classes of contemporary use insecticides-organophosphates (OPs) and N -methyl carbamates (NMCs)-and sperm concentration using robust and reproducible systematic review and meta-analysis methods.

METHODS

Three scientific databases (PubMed, Scopus, and Web of Science), two U.S. government databases (NIOSHTIC-2 and Science.gov), and five nongovernmental organization websites were searched for relevant primary epidemiological studies published in any language through 11 August 2022. Risk of bias and strength of evidence were evaluated according to Navigation Guide systematic review methodology. Bias-adjusted standardized mean difference effect sizes were calculated and pooled using a three-level, multivariate random-effect meta-analysis model with cluster-robust variance estimation.

RESULTS

Across 20 studies, 21 study populations, 42 effect sizes, and 1,774 adult men, the pooled bias-adjusted standardized mean difference in sperm concentration between adult men more- and less-exposed to OP and NMC insecticides was - 0.30 (95% CI: - 0.49 , - 0.10 ; P Satt < 0.01 ). Sensitivity and subgroup analyses explored statistical heterogeneity and validated the model robustness. Although the pooled effect estimate was modified by risk of bias, insecticide class, exposure setting, and recruitment setting, it remained negative in direction across all meta-analyses. The body of evidence was rated to be of moderate quality, with sufficient evidence of an association between higher adult OP and NMC insecticide exposure and lower sperm concentration.

DISCUSSION

This comprehensive investigation found sufficient evidence of an association between higher OP and NMC insecticide exposure and lower sperm concentration in adults. Although additional cohort studies can be beneficial to fill data gaps, the strength of evidence warrants reducing exposure to OP and NMC insecticides now to prevent continued male reproductive harm. https://doi.org/10.1289/EHP12678.

Comparative study on the removal of 1- naphthol and 2-naphthol by ferrate (VI): Kinetics, reaction mechanisms and theoretical calculations

In this study, the oxidation of 1-naphthol (1-NAP) and 2-T (2-NAP) by Fe(VI) was investigated. The impacts of operating factors were investigated through a series of kinetic experiments, including Fe(VI) dosages, pH and coexisting ions (Ca²⁺, Mg²⁺, Cu2⁺, Fe³⁺, Cl^-, SO₄^2-, NO₃^- and CO₃^2-). Almost 100% elimination of both 1-NAP and 2-NAP could be achieved within 300 s at pH 9.0 and 25 °C. Cu²⁺ could significantly improve the degradation efficiency of 1-NAP and 2-NAP, but the impacts of other ions were negligible. The liquid chromatography-mass spectrometry was used to identify the transformation products of 1-NAP and 2-NAP in Fe(VI) system, and the degradation pathways were proposed accordingly. Electron transfer mediated polymerization reaction was the dominant transformation pathway in the elimination of NAP by Fe(VI) oxidation. After 300 s of oxidation, heptamers and hexamers were found as the final coupling products during the removal of 1-NAP and 2-NAP, respectively. Theoretical calculations demonstrated that the hydrogen abstraction and electron transfer reaction would easily occur at the hydroxyl groups of 1-NAP and 2-NAP, producing NAP phenoxy radicals for subsequent coupling reaction. Moreover, since the electron transfer reactions between Fe(VI) and NAP molecules were barrierless and could occur spontaneously, the theoretical calculation results also confirmed the priority of coupling reaction in Fe(VI) system. This work indicated that the Fe(VI) oxidation was an effective way for removing naphthol, which may help us understand the reaction mechanism between phenolic compounds with Fe(VI).

Establishing the relationship between Polycyclic Aromatic Hydrocarbons (PAHs) exposure and male infertility: A systematic review

It has been demonstrated that human exposure to environmental chemicals may have sperm genotoxic potentiality. Among the different classes, Polycyclic Aromatic Hydrocarbons (PAHs) have been receiving attention in recent years due to reports of sperm geno-toxicity, a series of reproductive defects and male infertility. This review aims to substantiate the effects of PAHs exposure on male infertility, with focus on the sperm characteristics (count, concentration, volume, motility, DNA damage, and morphology). To this end, international databases such as Cochrane Library, PubMed, Web of Science, Embase Ovid, Scopus, and Google Scholar were used to conduct a systematic search for papers on the subject, based on PRISMA guidelines, published up to 24 March 2022. The Newcastle-Ottawa Scale was subsequently used to assess the quality of the studies. The results showed that there is a significant negative relationship between PAHs metabolites and sperm volume, concentration, motility, morphology, as well as an observed DNA degeneration. Also, the CYP1A1 genotype polymorphisms were considered as a representative of PAHs exposure to infertility; the review highlights that polymorphisms of this genotype were more common in the infertile people. In overall, this work provides a solid summary of the existing works correlating PAHs exposure and male infertility, which could impulse further protective measures and informative campaigns on users, workers, and general population.

Rapid Determination of Mixed Pesticide Residues on Apple Surfaces by Surface-Enhanced Raman Spectroscopy

Chlorpyrifos (CPF) and 2,4-dichlorophenoxyacetic acid (2,4-D) are insecticides and herbicides which has been widely used on farms. However, CPF and 2,4-D residues on corps can bring high risks to human health. Accurate detection of pesticide residues is important for controlling health risks caused by CPF and 2,4-D. Therefore, we developed a fast, sensitive, economical, and lossless surface-enhanced Raman spectroscopy (SERS)-based method for pesticide detection. It can rapidly and simultaneously determine the CPF and 2,4-D mixed pesticide residues on an apple surface at a minimum of 0.001 mg L⁻¹ concentration, which is far below the pesticide residue standard in China and the EU. The limits of detection reach down to 1.28 × 10⁻⁹ mol L⁻¹ for CPF and 2.47 × 10⁻¹⁰ mol L⁻¹ for 2,4-D. The limits of quantification are 4.27 × 10⁻⁹ mol L⁻¹ and 8.23 × 10⁻¹⁰ mol L⁻¹ for CPF and 2,4-D. This method has a great potential for the accurate detection of pesticide residues, and may be applied to other fields of agricultural products and food industry.

Photochemical reaction of superoxide radicals with 1-naphthol

The photochemical reactions between 1-naphthol (1-NP) and the superoxide anion radical (O2•–) were investigated in detail by using 365 nm UV irradiation. The results showed that the conversion rate of 1-NP decreased with the increase of the initial concentration of 1-NP, whereas by increasing the pH and riboflavin concentration, the photochemical reaction was accelerated. The second-order reaction rate constant was estimated to be (3.64 ± 0.17) × 108 L mol−1 s−1. The major photolysis products identified by using gas chromatography – mass spectrometry (GC–MS) were 1,4-naphquinone and 2,3-epoxyresin-2,3-dihydro-1,4-naphquinone, and their reaction pathways were also discussed. An atmospheric model showed that both the bulk water reaction and the heterogeneous surface reaction deserve attention in atmospheric aqueous chemistry.

Performance of urine, blood, and integrated metal biomarkers in relation to birth outcomes in a mixture setting

BACKGROUND

Studies on the health effects of metal mixtures typically utilize biomarkers measured in a single biological medium, such as blood or urine. However, the ability to evaluate mixture effects are limited by the uncertainty whether a unified medium can fully capture exposure for each metal. Therefore, it is important to compare and assess metal mixtures measured in different media in epidemiology studies.

OBJECTIVES

The aim of this study was to examine the mixture predictive performance of urine and blood metal biomarkers and integrated multi-media biomarkers in association with birth outcomes.

METHODS

In our analysis of 847 women from the Puerto Rico PROTECT Cohort, we measured 10 essential and non-essential metals in repeated and paired samples of urine and blood during pregnancy. For each metal, we integrated exposure estimates from paired urine and blood biomarkers into multi-media biomarkers (MMBs), using intraclass-correlation coefficient (ICC) and weighted quantile sum (WQS) approaches. Using Ridge regressions, four separate Environmental risk scores (ERSs) for metals in urine, blood, MMBICC, and MMBWQS were computed as a weighted sum of the 10 metal concentrations. We then examined associations between urine, blood, and multi-media biomarker ERSs and birth outcomes using linear and logistic regressions, adjusting for maternal age, maternal education, pre-pregnancy body mass index (BMI), and second-hand smoke exposure. The performance of each ERS was evaluated with continuous and tertile estimates and 95% confidence intervals of the odds ratio of preterm birth using area under the curve (AUC).

RESULTS

Pb was the most important contributor of blood ERS as well as the two integrated multi-media biomarker ERSs. Individuals with high ERS (3rd tertile) showed increased odds of preterm birth compared to individuals with low ERS (1st tertile), with 2.8-fold (95% CI, 1.49 to 5.40) for urine (specific gravity corrected); 3.2- fold (95% CI, 1.68 to 6.25) for blood; 3.9-fold (95% CI, 1.72 to 8.66) for multi-media biomarkers composed using ICC; and 5.2-fold (95% CI, 2.34 to 11.42) for multi-media biomarkers composed using WQS. The four ERSs had comparable predictive performances (AUC ranging from 0.64 to 0.68) when urine is examined with specific gravity corrected concentrations.

CONCLUSIONS

Within a practical metal panel, measuring metals in either urine or blood may be an equally good approach to evaluate the metals as a mixture. Applications in practical study design require validation of these methods with other cohorts, larger panels of metals and within the context of other adverse health effects of interest.

Health Effects of Naphthalene Exposure: A Systematic Evidence Map and Analysis of Potential Considerations for Dose-Response Evaluation

BACKGROUND

Naphthalene is a polycyclic aromatic hydrocarbon that has been associated with health effects, including cancer. As the state of the science on naphthalene toxicity continues to evolve, updated toxicity reference value(s) may be required to support human health risk assessment.

OBJECTIVES

We present a systematic evidence map of studies that could be used to derive toxicity reference value(s) for naphthalene.

METHODS

Human and animal health effect studies and physiologically based pharmacokinetic (PBPK) models were identified from a literature search based on populations, exposures, comparators, and outcomes (PECO) criteria. Human and animal studies meeting PECO criteria were refined to a smaller subset considered most informative for deriving chronic reference value(s), which are preferred for assessing risk to the general public. This subset was evaluated for risk of bias and sensitivity, and the suitability of each study for dose-response analysis was qualitatively assessed. Lowest observed adverse effect levels (LOAELs) were extracted and summarized. Other potentially relevant studies (e.g., mechanistic and toxicokinetic studies) were tracked as supplemental information but not evaluated further. Existing reference values for naphthalene are also summarized.

RESULTS

We identified 26 epidemiology studies and 16 animal studies that were considered most informative for further analysis. Eleven PBPK models were identified. The available epidemiology studies generally had significant risk of bias and/or sensitivity concerns and were mostly found to have low suitability for dose-response analysis due to the nature of the exposure measurements. The animal studies had fewer risk of bias and sensitivity concerns and were mostly found to be suitable for dose-response analysis.

CONCLUSION

Although both epidemiological and animal studies of naphthalene provide weight of evidence for hazard identification, the available animal studies appear more suitable for reference value derivation. PBPK models and mechanistic and toxicokinetic data can be applied to extrapolate these animal data to humans, considering mode of action and interspecies metabolic differences. https://doi.org/10.1289/EHP7381.

Urinary metabolites of non-persistent pesticides and serum hormones in Spanish adolescent males

OBJECTIVE

To assess the relationship of urinary concentrations of ethylenethiourea (ETU), the main degradation product of ethylene bis-dithiocarbamate fungicides, 3-phenoxybenzoic acid (3-PBA), a common metabolite of many pyrethroids, and 1-naphthol (1N), a metabolite of the carbamate insecticide carbaryl, with hormone concentrations in adolescent males; and to examine interactions between pesticide metabolites and polymorphisms in xenobiotic metabolizing enzymes, including CYP2C19 and CYP2D6, in relation to hormone concentrations.

METHODS

A cross-sectional study was conducted in 134 males from the Spanish Environment and Childhood (INMA)-Granada cohort. Urine and serum samples were collected from participants during the same clinical visit at the age of 15-17 years. First morning urine void was analyzed for concentrations of ETU, 3-PBA, and 1N. Serum was analyzed for concentrations of reproductive hormones (testosterone, 17β-estradiol [E₂], dehydroepiandrosterone sulfate [DHEAS], sex hormone binding globulin [SHBG], luteinizing hormone [LH], follicle stimulating hormone [FSH], anti-Müllerian hormone [AMH], and prolactin), thyroid hormones (free thyroxine [FT4], total triiodothyronine [TT3], and thyroid stimulating hormone [TSH]), insulin growth factor 1 (IGF-1), adrenocorticotropic hormone (ACTH), and cortisol. CYP2C19 G681A and CYP2D6 G1846A polymorphisms were determined in blood from 117 participants. Multiple linear regression, interaction terms, and stratified analyses were performed.

RESULTS

Urinary ETU was detected in 74.6% of participants, 1N in 38.1%, and 3-PBA in 19.4%. Positive associations between detectable 3-PBA and TT3 and between detectable 1N and DHEAS were found, and marginally-significant associations of 1N with reduced E₂ and FSH were observed. Poor CYP2C19 and CYP2D6 metabolizers (GA and AA genotype carriers) showed a greater increase in DHEAS for detected versus undetected 1N compared with GG genotype carriers. Poor CYP2D6 metabolizers (1846 GA and AA genotypes) evidenced increased cortisol for detected versus undetected ETU.

CONCLUSIONS

The associations observed between urinary pesticide metabolites and altered thyroid and reproductive hormones are novel and should be verified in studies with larger sample size. Further research on gene-environment interactions is warranted to establish individual susceptibility to pesticides and the risk of adverse health effects.

Insights into the microbial degradation and catalytic mechanisms of chlorpyrifos

Chlorpyrifos is extensively used worldwide as an insecticide to control various insect pests. Long-term and irregular applications of chlorpyrifos have resulted in large-scale soil, groundwater, sediment, and air pollution. Numerous studies have shown that chlorpyrifos and its major intermediate metabolite 3,5,6-trichloropyridinol (TCP) accumulate in non-target organisms through biomagnification and have a strong toxic effect on non-target organisms, including human beings. Bioremediation based on microbial metabolism is considered an eco-friendly and efficient strategy to remove chlorpyrifos residues. To date, a variety of bacterial and fungal species have been isolated and characterized for the biodegradation of chlorpyrifos and TCP. The metabolites and degradation pathways of chlorpyrifos have been investigated. In addition, the chlorpyrifos-degrading enzymes and functional genes in microbes have been reported. Hydrolases can catalyze the first step in ester-bond hydrolysis, and this initial regulatory metabolic reaction plays a key role in the degradation of chlorpyrifos. Previous studies have shown that the active site of hydrolase contains serine residues, which can initiate a catalytic reaction by nucleophilic attack on the P-atom of chlorpyrifos. However, few reviews have focused on the microbial degradation and catalytic mechanisms of chlorpyrifos. Therefore, this review discusses the deep understanding of chlorpyrifos degradation mechanisms with microbial strains, metabolic pathways, catalytic mechanisms, and their genetic basis in bioremediation.

Pharmacological Actions of Carbamate Insecticides at Mammalian Melatonin Receptors

Integrated in silico chemical clustering and melatonin receptor molecular modeling combined with in vitro 2-[125I]-iodomelatonin competition binding were used to identify carbamate insecticides with affinity for human melatonin receptor 1 (hMT1) and human melatonin receptor 2 (hMT2). Saturation and kinetic binding studies with 2-[125I]-iodomelatonin revealed lead carbamates (carbaryl, fenobucarb, bendiocarb, carbofuran) to be orthosteric ligands with antagonist apparent efficacy at hMT1 and agonist apparent efficacy at hMT2 Furthermore, using quantitative receptor autoradiography in coronal brain slices from C3H/HeN mice, carbaryl, fenobucarb, and bendiocarb competed for 2-[125I]-iodomelatonin binding in the suprachiasmatic nucleus (SCN), paraventricular nucleus of the thalamus (PVT), and pars tuberalis (PT) with affinities similar to those determined for the hMT1 receptor. Carbaryl (10 mg/kg i.p.) administered in vivo also competed ex vivo for 2-[125I]-iodomelatonin binding to the SCN, PVT, and PT, demonstrating the ability to reach brain melatonin receptors in C3H/HeN mice. Furthermore, the same dose of carbaryl given to C3H/HeN mice in constant dark for three consecutive days at subjective dusk (circadian time 10) phase-advanced circadian activity rhythms (mean = 0.91 hours) similar to melatonin (mean = 1.12 hours) when compared with vehicle (mean = 0.04 hours). Carbaryl-mediated phase shift of overt circadian activity rhythm onset is likely mediated via interactions with SCN melatonin receptors. Based on the pharmacological actions of carbaryl and other carbamate insecticides at melatonin receptors, exposure may modulate time-of-day information conveyed to the master biologic clock relevant to adverse health outcomes. SIGNIFICANCE STATEMENT: In silico chemical clustering and molecular modeling in conjunction with in vitro bioassays identified several carbamate insecticides (i.e., carbaryl, carbofuran, fenobucarb, bendiocarb) as pharmacologically active orthosteric melatonin receptor 1 and 2 ligands. This work further demonstrated that carbaryl competes for melatonin receptor binding in the master biological clock (suprachiasmatic nucleus) and phase-advances overt circadian activity rhythms in C3H/HeN mice, supporting the relevance of circadian effects when interpreting toxicological findings related to carbamate insecticide exposure.

Cytotoxicity and genotoxicity of methomyl, carbaryl, metalaxyl, and pendimethalin in human umbilical vein endothelial cells

Pesticides have adverse effects on the cellular functionality, which may trigger myriad of health consequences. However, pesticides-mediated toxicity in the endothelial cells (ECs) is still elusive. Hence, in this study, we have used human umbilical vein endothelial cells (HUVECs) as a model to quantify the cytotoxicity and genotoxicity of four pesticides (methomyl, carbaryl, metalaxyl, and pendimethalin). In the MTT assay, HUVECs exposed to methomyl, carbaryl, metalaxyl, and pendimethalin demonstrated significant proliferation inhibition only at higher concentrations (500 and 1000 μM). Likewise, neutral red uptake (NRU) assay also showed proliferation inhibition of HUVECs at 500 and 1000 μM by the four pesticides, confirming lysosomal fragility. HUVECs exposed to the four pesticides significantly increased the level of intracellular reactive oxygen species (ROS). Comet assay and flow cytometric data exhibited DNA damage and apoptotic cell death in HUVECs after 24 h of exposure with methomyl, metalaxyl, carbaryl, and pendimethalin. This is a first study on HUVECs signifying the cytotoxic-genotoxic and apoptotic potential of carbamate insecticides (methomyl and carbaryl), fungicide (metalaxyl), and herbicide (pendimethalin). Overall, these pesticides may affect ECs functions and angiogenesis; nonetheless, mechanistic studies are warranted from the perspective of vascular biology using in vivo test models.

Lowland tapir exposure to pesticides and metals in the Brazilian Cerrado

Abstract ContextThe Cerrado is a Global Biodiversity Hotspot as well as Brazil’s main frontier for large-scale agriculture and livestock production, making it one of the most threatened biomes in the country. Brazil is one of the biggest consumers of pesticides in the world and allows the use of chemicals that are banned in many other countries due to their adverse health effects in a wide range of species, including humans. AimsThis study aimed to assess pesticide and metal exposure of the lowland tapir – a threatened, large herbivorous mammal – to support future studies of the role of these chemicals in tapir health, survivorship, and population viability. MethodsFoot pad, proboscis, stomach contents, liver, bone, and nail samples were obtained from tapir carcasses found along highways (n=87). (i) Atomic absorption spectrophotometry (AAS) was used to detect metals in bone, nail and liver tissue; (ii) gas chromatography – nitrogen phosphorous detector (GC-NPD) to detect organophosphates in liver and skin; and (iii) high performance liquid chromatography – ultraviolet (HPLC-UV) to detect pyrethroids and carbamates in stomach contents. Key resultsTwo carbamates (aldicarb and carbaryl), three organophosphates (diazinon, malathion, and mevinphos), two pyrethroids (deltamethrin and permethrin), and two toxic metals (cadmium and lead) were detected in different tapir tissue samples, some at concentrations high enough to cause adverse health effects. In 90% of roadkill tapirs that were subjected to a full post-mortem examination (n=25), macroscopic alterations of liver and/or kidney tissue were observed. ConclusionsThis study provides the first report to date of the detection of pesticides and metals in lowland tapirs. ImplicationsSome of the reported pesticide concentrations exceed environmental safety thresholds. Consequently, results from this study raise concerns over potential adverse health effects in tapirs that could lead to population level impacts, thus requiring further investigation.

Review of emerging contaminant tris(1,3-dichloro-2-propyl)phosphate: Environmental occurrence, exposure, and risks to organisms and human health

Tris(1,3-dichloro-2-propyl)phosphate (TDCPP) is a halogen-containing organophosphorus chemical that is widely employed in various consumer products with a high production volume. As an additive flame retardant (FR), TDCPP tends to be released into the environment through multiple routes. It is ubiquitous in environmental media, biotic matrixes, and humans, and thus is deemed to be an emerging environmental contaminant. To date, significant levels of TDCPP and its primary diester metabolite, bis(1,3-dichloro-2-propyl)phosphate, have been detected in human samples of seminal plasma, breast milk, blood plasma, placenta, and urine, thereby causing wide concern about the potential human health effects resulting from exposure to this chemical. Despite the progress in research on TDCPP over the past few years, we are still far from fully understanding the environmental behavior and health risks of this emerging contaminant. Thus, this paper critically reviews the environmental occurrence, exposure, and risks posed by TDCPP to organisms and human health among the literature published in the last decade. It has been demonstrated that TDCPP induces acute-, nerve-, developmental-, reproductive-, hepatic-, nephron-, and endocrine-disrupting toxicity in animals, which has caused increasing concern worldwide. Simultaneously, TDCPP induces cytotoxicity by increasing the formation of reactive oxygen species and inducing endoplasmic reticulum stress in multiple human cell lines in vitro, and also causes endocrine-disrupting effects, including reproductive dysfunction and adverse pregnancy outcomes, according to human epidemiology studies. This review not only provides a better understanding of the behavior of this emerging contaminant in the environment, but also enhances the comprehension of the health risks posed by TDCPP exposure to ecosystems and humans.

Endocrine-disrupting chemicals: implications for human health

Since reports published in 2015 and 2016 identified 15 probable exposure-outcome associations, there has been an increase in studies in humans of exposure to endocrine-disrupting chemicals (EDCs) and a deepened understanding of their effects on human health. In this Series paper, we have reviewed subsequent additions to the literature and identified new exposure-outcome associations with substantial human evidence. Evidence is particularly strong for relations between perfluoroalkyl substances and child and adult obesity, impaired glucose tolerance, gestational diabetes, reduced birthweight, reduced semen quality, polycystic ovarian syndrome, endometriosis, and breast cancer. Evidence also exists for relations between bisphenols and adult diabetes, reduced semen quality, and polycystic ovarian syndrome; phthalates and prematurity, reduced anogenital distance in boys, childhood obesity, and impaired glucose tolerance; organophosphate pesticides and reduced semen quality; and occupational exposure to pesticides and prostate cancer. Greater evidence has accumulated than was previously identified for cognitive deficits and attention-deficit disorder in children following prenatal exposure to bisphenol A, organophosphate pesticides, and polybrominated flame retardants. Although systematic evaluation is needed of the probability and strength of these exposure-outcome relations, the growing evidence supports urgent action to reduce exposure to EDCs.

Genome-wide analysis of DNA methylation in testis of male rat exposed to chlorpyrifos

In our previous study, we found that subchronic exposure of chlorpyrifos (CPF) can cause reproductive damage in male rats. However, the mechanisms underlying the reproductive effects of CPF are not well understood. DNA methylation is essential for epigenetic gene regulation in development and disease. Therefore, we aim to compare DNA methylation profiles between controls and CPF-treated rats in order to identify the epigenetic mechanism of male reproductive toxicity induced by CPF. Methylated DNA immunoprecipitation with high-throughput sequencing (MeDIP-seq) was used to investigate the genome-wide DNA methylation pattern in testes of control and CPF-treated rats for 90 days. We identified 27 019 differentially methylated regions (DMRs) (14 150 upmethylated and 12 869 downmethylated) between CPF-exposed and control groups. The DMR-related genes are mainly involved in 113 pathways predicted by Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. The result showed that high methylation gene PIK3CD may play a key role in epigenetic regulation of multiple pathways, such as Ras signaling pathway, AGE-RAGE signaling pathway in diabetic complications, HIF-1 signaling pathway, VEGF signaling pathway, and glioma and Fc epsilon RI signaling pathway in rats exposed to CPF. Our study provides significant explanations for the epigenetic mechanism of male reproductive toxicology induced by CPF.

Pesticide interactions and risks of sperm chromosomal abnormalities

Disentangling the separate and synergistic effects of chemicals poses methodological challenges for accurate exposure assessment and for investigating epidemiologically how chemicals affect reproduction. We investigated combined exposures to ubiquitous contemporary use pesticides, specifically organophosphates (OP) and pyrethroids (PYR), and their association with germ cell abnormalities among adult men. Fluorescence in situ hybridization was used to determine disomy in sperm nuclei and urine was analyzed for concentrations of PYR metabolites (3-phenoxybenzoic acid; 3PBA) and OP dialkyl phosphate (DAP) metabolites. Incidence rate ratios using Poisson models were estimated for each disomy type by exposure quartile of DAP metabolites and 3PBA, controlling for confounders. The shape of the associations between PYRs, OPs and disomy were frequently nonmonotonic. There were consistent interactions between OP and PYR metabolite concentrations and the risk for sperm abnormalities. Taking both chemicals into account simultaneously resulted in quantitatively different associations than what was reported previously for OPs and PYRs separately, demonstrating the importance of modeling multiple concentrations simultaneously. Methods investigating interactions using Poisson models are needed to better quantify chemical interactions and their effects on count-based health outcomes, the importance of which was shown here for germ cell abnormalities.

Human Semen Quality, Sperm DNA Damage, and the Level of Urinary Concentrations of 1N and TCPY, the Biomarkers of Nonpersistent Insecticides

The aim of the study was to evaluate the association between environmental exposure to nonpersistent insecticides and semen quality (concentration, motility, morphology, computer-aided semen analysis [CASA] parameters, and sperm DNA damage). Urine samples (n = 315) collected from men who attended the infertility clinic with normal semen concentration of 15 to 300 mln/ml and age under 45 years were analyzed for two metabolites (1-naphthol [1N] and 3,5,6-trichloro-2-pyridinol [TCPY]) of nonpersistent insecticides. Participants provided semen, blood, and saliva samples; additionally, men filled a detailed questionnaire. The results identified that urinary TCPY concentration was significantly associated with a decrease in motility; also there was a positive association between TCPY and DNA fragmentation index (DFI). 1N concentration was negatively associated with a percentage of sperm with normal morphology and positively with one of the CASA parameters (curvilinear velocity [VCL]). The results suggest that environmental exposure to nonpersistent insecticides may have an impact on semen quality parameters and sperm DNA damage.

Effects of the water-soluble fraction of diesel oil (WSD) on the fertilization and development of a sea urchin (Echinometra lucunter)

Considering the high number of accidents with diesel oil spills occurring in the marine ecosystem, toxicity tests aimed at assessing the effects of this pollutant on biota are necessary and urgent. Thus, the present study aimed to evaluate the toxicity of the soluble fraction of diesel oil (WSD) in the fertilization success of gametes and pluteu larvae of the sea urchin Echinometra lucunter. To do this, gametes and embryos were exposed to concentrations of 0% (control group), 0.5%, 1.5% and 2.5% of WSD. The fertilization success of exposed gametes and embryos were reduced significantly when compared to the control group in all tested concentrations. With this finding, it is evident that diesel oil can be significantly promoted in the early and adult life stages of a particular organism, and a better way of evaluating this toxicity is through the analysis of contaminant effects throughout the reproductive cycle of a species.

Cloning and expression of the carbaryl hydrolase gene mcbA and the identification of a key amino acid necessary for carbaryl hydrolysis

Carbamate hydrolase is the initial and key enzyme for degradation of carbamate pesticides. In the present study, we report the isolation of a carbaryl-degrading strain Pseudomonas sp. XWY-1, the cloning of its carbaryl hydrolase gene (mcbA) and the characterization of McbA. Strain XWY-1 was able to utilize carbaryl as a sole carbon source and degrade it using 1-naphthol as an intermediate. Transposon mutagenesis identified a mutant of XWY-1M that was unable to hydrolyze carbaryl. The transposon-disrupted gene mcbA was cloned by self-formed adaptor PCR, then expressed in Escherichia coli BL21(DE3) and purified. McbA was able to hydrolyze carbamate pesticides including carbaryl, isoprocarb, fenobucarb, carbofuran efficiently, while it hydrolyzed aldicarb, and propoxur poorly. The optimal pH of McbA was 7.0 and the optimal temperature was 40°C. The apparent K_m and k_cat values of McbA for carbaryl were 77.67±12.31μM and 2.12±0.10s^-1, respectively. Three amino acid residues (His467, His477 and His504) in the predicted polymerase/histidinol phosphatase-like domain were shown to be closely related to the activity of McbA, with His504 being the most important, as a replacement of His504 led to the complete loss of activity. This is the first study to identify key amino acids in McbA.

Giant toads (Rhinella marina) living in agricultural areas have altered spermatogenesis

Across diverse taxa, germ cell development is controlled by an intricate cascade of processes that are tightly controlled by the hypothalamic-pituitary-gonadal axis. Endocrine disturbances, such as those induced by endocrine disrupting chemicals (EDCs) can negatively affect spermatogenesis. Here, we investigate whether spermatogenesis is altered in the giant toad, Rhinella marina, living in agricultural areas where EDCs are used relative to suburban areas. We also ask if reductions in spermatogenesis were associated with developmental gonadal abnormalities (intersex) found in the same frogs. We found that toads in agricultural areas exhibited reduced spermatogenesis relative to non-agricultural animals, and that those reductions were not associated with gross gonadal abnormalities. All toads living in agricultural areas had reduced spermatogenesis relative to those living in non-agricultural areas regardless of whether they had gonadal abnormalities originating during development. Similarities in reproductive dysfunction among diverse taxa living in agricultural areas, including humans, suggest that many vertebrate taxa living in agricultural areas around the globe are likely experiencing some level of reproductive dysfunction.

New insights into urine-based assessment of polycyclic aromatic hydrocarbon-exposure from a rat model: Identification of relevant metabolites and influence of elimination kinetics

A gas chromatography tandem mass-spectrometry method dedicated to the analysis of 50 metabolites of polycyclic aromatic hydrocarbons (OH-PAHs) was applied to urine specimens collected from female Long Evans rats under controlled exposure to a mixture of PAHs (at 7 doses ranging from 0.01 to 0.8 mg/kg, by gavage, 3 times per week for 90 days). On four occasions (day 1, 28, 60 and 90), urine samples were collected over a 24 h period. Among these 50 OH-PAHs, 41 were detected in urine samples. Seven additional OH-PAHs were identified for the first time: 1 corresponding to metabolite of pyrene and 3 of anthracene. Strong linear dose versus urinary concentration relationships were observed for 25 of the 41 OH-PAHs detected in rat urine, confirming their suitability for assessing exposure to their respective parent compound. In addition, some isomers (e.g. 1-OH-pyrene, 3-OH-/4-OH-chrysene, 10-OH-benz[a]anthracene, 8-OH-benzo[k]fluoranthene, 11-OH-benzo[b]fluoranthene and 3-OH-benzo[a]pyrene) that were detected starting from the lowest levels of exposure or even in controls were considered particularly relevant biomarkers compared to metabolites only detected at higher levels of exposure. Finally, on the basis of the excretion profiles (on days 1, 28, 60 and 90) and urinary elimination kinetics of each OH-PAH detected at days 1 and 60, this study highlighted the fact that sampling time may influence the measurement of metabolites in urine. Taken together, these results provide interesting information on the suitability of the analysis of OH-PAHs in urine for the assessment of PAH exposure, which could be taken into consideration for the design of epidemiological studies in the future.

Urinary metabolites of polycyclic aromatic hydrocarbons, sperm DNA damage and spermatozoa apoptosis

Inconsistent results between polycyclic aromatic hydrocarbons (PAHs) exposure and adverse male reproductive health have been reported in humans. To assess whether PAH exposure is associated with declined sperm function. Ten monohydroxylated PAHs (OH-PAHs) metabolites were analyzed in repeated urine samples from an infertility clinic. We used multivariable linear models to estimate the associations of urinary OH-PAH metabolites with sperm DNA damage (n=405) and spermatozoa apoptosis (n=366). The shapes of dose-dependent associations of exposure measurements with outcomes were further evaluated by restricted cubic splines. Multiple comparisons were adjusted by false discovery rate (FDR). We found that urinary 9-hydroxyfluorene (9-OHFlu) was associated with increased tail length and comet length (p for trend=0.05 and 0.01, respectively), and that urinary 9-hydroxyphenanthrene (9-OHPh) was associated with decreased percentage of Annexin V^-/PI^- spermatozoa (p for trend=0.04). Also, suggestive associations of urinary 9-OHPh and ∑OHFlu with increased comet length, and urinary 9-OHFlu and 2-OHPh with decreased percentage of Annexin V^-/PI^- spermatozoa were observed (all p for trends <0.10). Further, these dose-dependent associations were confirmed in restricted cubic splines. Our results suggest that environmental exposure to fluorene and phenanthrene are associated with declined sperm function.

The classic EDCs, phthalate esters and organochlorines, in relation to abnormal sperm quality: a systematic review with meta-analysis

The association between endocrine disrupting chemicals (EDCs) and human sperm quality is controversial due to the inconsistent literature findings, therefore, a systematic review with meta-analysis was performed. Through the literature search and selection based on inclusion criteria, a total of 9 studies (7 cross-sectional, 1 case-control, and 1 pilot study) were analyzed for classic EDCs (5 studies for phthalate esters and 4 studies for organochlorines). Funnel plots revealed a symmetrical distribution with no evidence of publication bias (Begg’s test: intercept = 0.40; p = 0.692). The summary odds ratios (OR) of human sperm quality associated with the classic EDCs was 1.67 (95% CI: 1.31–2.02). After stratification by specific chemical class, consistent increases in the risk of abnormal sperm quality were found in phthalate ester group (OR = 1.52; 95% CI: 1.09–1.95) and organochlorine group (OR = 1.98; 95% CI: 1.34–2.62). Additionally, identification of official data, and a comprehensive review of the mechanisms were performed, and better elucidated the increased risk of these classic EDCs on abnormal sperm quality. The present systematic review and meta-analysis helps to identify the impact of classic EDCs on human sperm quality. However, it still highlights the need for additional epidemiological studies in a larger variety of geographic locations.

Electrochemical and photophysical behavior of 1-naphthol in benzyl-n-hexadecyldimethylammonium 1,4-bis(2-ethylhexyl)sulfosuccinate large unilamellar vesicles

The behavior of 1-naphthol and its partition process in LUVs formed from a new catanionic surfactant were studied by electrochemical and spectroscopic techniques.

The reference values for semen parameters of 1213 fertile men in Guangdong Province in China

Semen samples were collected from 1213 fertile men whose partners had a time-to-pregnancy (TTP) ≤12 months in Guangdong Province in Southern China, and semen parameters including semen volume, sperm concentration, total counts, motility, and morphology were evaluated according to the World Health Organization (WHO) 2010 guideline. All semen parameters analyzed were normal in ~62.2% of the total samples, whereas ~37.8% showed at least one of the semen parameters below normal threshold values. The fifth centiles (with 95% confidence intervals) were 1.3 (1.2–1.5) ml for semen volume, 20 × 10⁶ (18×10⁶–20×10⁶) ml⁻¹ for sperm concentration, 40 × 10⁶ (38×10⁶–44×10⁶) per ejaculate for total sperm counts, 48% (47%–53%) for vitality, 39% (36%–43%) for total motility, 25% (23%–27%) for sperm progressive motility, 5.0% (4%–5%) for normal morphology. The pH values ranged from 7.2 to 8.0 with the mean ± standard deviation at 7.32 ± 0.17. No effects of age and body mass index were found on semen parameters. Occupation, smoking and alcohol abuse, varicocele appeared to decrease semen quality. Sperm concentration, but not sperm morphology, is positively correlated with TTP, whereas vitality is negatively correlated with TTP. Our study provides the latest reference values for the semen parameters of Chinese fertile men in Guangdong Province, which are close to those described in the new WHO guidelines (5^th Edition).

Influence of body mass index status on urinary creatinine and specific gravity for epidemiological study of children

In epidemiological studies, urinary biomonitoring is a valid approach to assess the association between environmental chemical exposure and children's health. Many clinical biomarkers (e.g., endogenous metabolites) are also based on analysis of urine. Considering the variability in urinary output, urinary concentrations of chemicals are commonly adjusted by creatinine and specific gravity (SG). However, there is a lack of systematic evaluation of their appropriateness for children. Furthermore, urinary SG and creatinine excretion could be influenced by body mass index (BMI), but the effect of BMI status on the two correction factors is unknown. We measured SG and creatinine concentrations of repeated first morning urine samples collected from 243 primary school children (8-11 years) over 5 consecutive weekdays. Urinary SG presented a higher temporal consistency compared with creatinine. Urinary SG was associated with sex (p < 0.001), whereas sex (p =0.034) and BMI (p = 00.008) were associated with urinary creatinine levels. Inter-day collection time was not associated with SG or creatinine after excluding the effect of Monday as a confounder. When stratified by BMI status, none of the factors were associated with creatinine among the overweight and obese children.

CONCLUSION

Generally, SG is preferable for correcting the variability in urinary output for children although creatinine correction may also perform well in overweight and obese children. SG correction is recommended for epidemiological exposure analysis in children based on urinary levels of exogenous or endogenous metabolites.

Human urinary/seminal phthalates or their metabolite levels and semen quality: A meta-analysis

Health concerns surrounding human exposure to phthalates include diminished semen quality. Epidemiological findings remain inconsistent. We have performed a quality appraisal and meta-analysis to quantitatively summarize evidence for associations between phthalate exposures and human semen quality. Pubmed and Web of Science were searched for pertinent studies through October 2014. Cited references were reviewed to identify secondary studies. Studies that reported quantitative estimates of the association between phthalates or their metabolite levels in humans and semen quality were eligible. Random effects models were used to calculate pooled effects estimates. Overall, 20 studies met our inclusion criteria. Subsequently, 14 studies were included in the meta-analysis. Urinary monobutyl phthalate (MBP) and monobenzyl phthalate (MBzP) were associated with reduced sperm concentration (MBP [7.4-25.3 µg/L], pooled odds ratio [OR]=2.60, 95% confidence interval [CI]=1.32-5.15; MBzP [14.0-540.2 µg/L], pooled OR=2.23, 95% CI=1.16-4.30). Both MBP (24.6-14,459.0 µg/L) and MEHP (3.1-208.1 µg/L) were inversely associated with straight line velocity (VSL; MBP, pooled β=-2.51, 95% CI=-4.44, -0.59; MEHP, pooled β=-1.06, 95% CI=-1.99, -0.12). An IQR increase in MBzP and MEP levels (MBzP, IQR=11.35 µg/L; MEP, IQR=449.4 µg/L) was associated with an increase in comet extent (CE; MBzP, pooled β=3.57, 95% CI=0.89-6.25; MEP, pooled β=4.22, 95% CI=1.66-6.77). No associations were observed between monomethyl phthalate and any semen parameters. Our meta-analysis strengthens the evidence that specific phthalates or their metabolite levels may affect semen quality.

Effect of nonpersistent pesticides on estrogen receptor, androgen receptor, and aryl hydrocarbon receptor

Nonpersistent pesticides are considered less harmful for the environment, but their impact as endocrine disruptors has not been fully explored. The pesticide Switch was applied to grape vines, and the maximum residue concentration of its active ingredients was quantified. The transactivation potential of the pesticides Acorit, Frupica, Steward, Reldan, Switch, Cantus, Teldor, and Scala and their active compounds (hexythiazox, mepanipyrim, indoxacarb, chlorpyrifos-methyl, cyprodinil, fludioxonil, boscalid, fenhexamid, and pyrimethanil) were tested on human estrogen receptor α (ERα), androgen receptor (AR) and arylhydrocarbon receptor (AhR) in vitro. Relative binding affinities of the pure pesticide constituents for AR and their effect on human breast cancer and prostate cancer cell lines were evaluated. Residue concentrations of Switch's ingredients were below maximum residue limits. Fludioxonil and fenhexamid were ERα agonists (EC50 -values of 3.7 and 9.0 μM, respectively) and had time-dependent effects on endogenous ERα-target gene expression (cyclin D1, progesterone receptor, and nuclear respiratory factor 1) in MCF-7 human breast cancer cells. Fludioxonil, mepanipyrim, cyprodinil, pyrimethanil, and chlorpyrifos-methyl were AhR-agonists (EC50 s of 0.42, 0.77, 1.4, 4.6, and 5.1 μM, respectively). Weak AR binding was shown for chlorpyrifos-methyl, cyprodinil, fenhexamid, and fludioxonil. Assuming a total uptake which does not take metabolism and clearance rates into account, our in vitro evidence suggests that pesticides could activate pathways affecting hormonal balance, even within permitted limits, thus potentially acting as endocrine disruptors.

Occupation exposures and sperm morphology: a case-referent analysis of a multi-centre study

OBJECTIVE

We examined occupational exposures and sperm morphology to establish whether exposures implicated differed from those affecting motile sperm concentration.

METHODS

Computer aided sperm morphometric assessment was undertaken on morphology slides obtained as part of a multi-centre study in 1999-2002 of occupational factors in male infertility. Men attending 14 fertility clinics across the UK were recruited and gave a semen sample. Before results of the semen analysis were known, the men completed detailed questionnaires about their employment and lifestyle. Occupational exposures were assessed by occupational hygienists. Data were analysed using an unmatched case-referent design, allowing for clustering and for confounders. Three case definitions were used: poor morphology (normal morphology <4%), low motile sperm count (MSC) (<4.8×10(6)) and either condition.

RESULTS

Morphology results were available for 1861/2011 men employed at the time of recruitment. Of these 1861, 296 (15.9%) had poor morphology; of the 2011with sperm count, 453 (22.5%) had low MSC; 654/1981 (33.0%) had either condition. Poor morphology, adjusted for confounding, was related to self-reported lifetime exposure to lead (OR=1.33; 95% CI 1.00 to 1.75). Low MSC was also related to self-reported lead and to hygienist-assessed glycol ether exposure. Self-reported use of paint stripper (OR=1.47; 95% CI 1.07 to 2.03) and lead, but not glycol ether, were significantly related to the combined case definition.

CONCLUSIONS

While this study did not identify any occupational exposure uniquely related to sperm morphology, the capacity of the study to detect risk was increased by including morphology with sperm concentration and motility.

Air pollution and decreased semen quality: a comparative study of Chongqing urban and rural areas

To investigate the association and effects of air pollution level on male semen quality in urban and rural areas, this study examines the outdoor concentrations of particulate matter (PM10), sulfur dioxide (SO2), nitrous dioxide (NO2) and semen quality outcomes for 1346 volunteers in both urban and rural areas in Chongqing, China. We found the urban area has a higher pollution level than the rural area, contrasted with better semen quality in the rural residents, especially for sperm morphology and computer assistant semen analysis (CASA) motility parameters. A multivariate linear regression analysis demonstrates that concentrations of PM10, SO2, and NO2 significantly and negatively are associated with normal sperm morphology percentage (P < 0.001) and sperm kinetic parameters. In conclusion, exposure to higher concentrations of PM10, SO2, and NO2 in urban ambient air may account for worse semen quality in urban males.

Investigation of polycyclic aromatic hydrocarbon level in blood and semen quality for residents in Pearl River Delta Region in China

This study is the first one investigating the correlation between the concentration of polycyclic aromatic hydrocarbon (PAHs) in blood and semen qualities for residents in the Pearl River Delta (PRD) region in China. Blood samples from 53 infertile volunteers were studied for measures of semen quality and 16 PAHs. Information on the study subjects' living habits (such as smoking, drinking and preference of consumption for food) and general information (age, body-mass-index (BMI) and educational background) were also collected. Statistical results showed that age and BMI were significantly and negatively related to semen motilities. The total concentrations of PAHs (∑16 PAHs) in the blood were 12,010, 7493, 9105 and 8647ng/g for factory workers, office workers, technicians and salespersons, respectively. In addition, ∑16 PAHs in the blood of smokers, drinkers and heavy-taste food consumers were 11,950, 11,266 and 12,141ng/g, which were higher than those observed in nonsmokers (10,457ng/g), nondrinkers (10,920ng/g) and light-taste food consumers (9202ng/g), individually. Furthermore, the Pearson correlation analysis results showed significant positive correlations between BMI and ∑16 PAHs in the blood. Statistically significant correlations were observed between semen motilities and ∑16 PAHs in the blood as well. Logistic regression results showed that for each 1ng/g increase in ∑16 PAHs in blood samples, the log odds of experiencing a pregnancy decrease by 0.039 on average. However, more evidences are needed to clarify the impact of PAHs in the blood to male infertility.

Urinary phytoestrogen levels related to idiopathic male infertility in Chinese men

Phytoestrogens (PEs) are naturally occurring chemical constituents of certain plants. The internal PE exposures, mainly from diet, vary among different populations and in different regions due to various eating habits. To investigate the potential relationship between urinary PE levels and idiopathic male infertility and semen quality in Chinese adult males, 608 idiopathic infertile men and 469 fertile controls were recruited by eligibility screening procedures. Individual exposure to PEs was measured using UPLC-MS/MS as spot urinary concentrations of 6 PEs (daidzein, DAI; equol, EQU; genistein, GEN; naringenin, NAR; coumestrol, COU; and secoisolariciresinol, SEC), which were adjusted with urinary creatinine (CR). Semen quality was assessed by sperm concentration, number per ejaculum and motility. We found that exposures to DAI, GEN and SEC were significantly associated with idiopathic male infertility (P-value for trend=0.036; 0.002; and 0.0001, respectively), while these exposures had stronger association with infertile subjects with at least one abnormal semen parameter than those with all normal semen parameters. Exposures to DAI, GEN and SEC were also related to idiopathic male infertility with abnormal sperm concentration, number per ejaculum and motility (P-value for trend<0.05), while these exposures had stronger association with the infertile men with abnormal sperm number per ejaculum. These findings provide the evidence that PE exposures are related to male reproductive function and raise a public health concern because that exposure to PEs is ubiquitous in China.

Urinary metabolic biomarkers link oxidative stress indicators associated with general arsenic exposure to male infertility in a han chinese population

To investigate the hypothesis that general environmental arsenic (As) exposure can impair male fertility, we designed a case-control study examining possible correlations between the concentrations of different As species in urine [controls (n = 151) vs cases (n = 140)], urinary metabolic biomarkers [controls (n = 158) vs cases (n = 135)], and infertility characterized by poor semen quality. Regional participants were recruited sequentially from the affiliated hospitals of Nanjing Medical University. Elevated inorganic arsenate (Asi(V)) exposure was associated with infertility: in comparison with the first quartile, subjects with Asi(V) levels above the median were more likely to exhibit male idiopathic infertility with increasing adjusted odds ratios (AOR) of 4.9 [95% confidence interval (CI), 1.8-13.6] and 13.6 (95% CI, 4.8-38.6) at the third and fourth quartiles (P = 0.000 for trend), respectively. Other As species did not exhibit a significant dose-dependent correlation with infertility risk. Levels of urinary biomarkers correlated with both male infertility and Asi(V) concentrations [controls (n = 145) vs cases (n = 123)]; the latter correlation was independent of disease. These included acylcarnitines, aspartic acid, and hydroxyestrone, which were negatively associated with infertility, and uridine and methylxanthine, which were positively associated. In conclusion, for the first time we show that elevated urinary concentrations of Asi(V) from general As exposure are significantly associated with male infertility, and As species may exert toxicity via oxidative stress and sexual hormone disrupting mechanisms, as indicated by related biomarkers.

Association of exposure to phenols and idiopathic male infertility

Widespread human exposure to phenols has been documented recently, and some phenols which are potential endocrine disruptors have demonstrated adverse effects on male reproduction in animal and in vitro studies. However, implications about exposure to phenols and male infertility are scarce in humans. Case-control study of 877 idiopathic infertile men and 713 fertile controls was conducted. Urinary levels of bisphenol A, benzophenone-3, pentachlorophenol, triclosan, 4-tert-octylphenol (4-t-OP), 4-n-octylphenol (4-n-OP) and 4-n-nonylphenol (4-n-NP) and semen parameters were measured. After multivariate adjustment, we found 4-t-OP, 4-n-OP and 4-n-NP exposure was associated with idiopathic male infertility (p-value for trend: <0.0001, 0.014 and 0.001, respectively). Aside from these associations, 4-t-OP and 4-n-NP exposure was also associated with idiopathic male infertility with abnormal semen parameters. Moreover, we observed significant associations between sum alkylphenols (APs) exposure and idiopathic male infertility. There were no relationships between exposure to other phenols and idiopathic male infertility in the present study. Our study provides the first evidence that exposure to APs (4-t-OP, 4-n-OP and 4-n-NP) is associated with idiopathic male infertility.

Selective electrochemical recognition of the α-naphthol isomer and in situ immobilization of naphthoquinones for tunable electrocatalysis

Fits like a glove: Separationless and selective electrochemical oxidation of the α-naphthol (α-NAP) isomer yields naphthoquinone species on the surface of multiwalled carbon nanotubes, which can further catalyze the electro-oxidation of NADH and hydrazine at different potentials. The β-NAP isomer failed to show any such electro-oxidation.

Endocrine-disrupting chemicals: associated disorders and mechanisms of action

The incidence and/or prevalence of health problems associated with endocrine-disruption have increased. Many chemicals have endocrine-disrupting properties, including bisphenol A, some organochlorines, polybrominated flame retardants, perfluorinated substances, alkylphenols, phthalates, pesticides, polycyclic aromatic hydrocarbons, alkylphenols, solvents, and some household products including some cleaning products, air fresheners, hair dyes, cosmetics, and sunscreens. Even some metals were shown to have endocrine-disrupting properties. Many observations suggesting that endocrine disruptors do contribute to cancer, diabetes, obesity, the metabolic syndrome, and infertility are listed in this paper. An overview is presented of mechanisms contributing to endocrine disruption. Endocrine disruptors can act through classical nuclear receptors, but also through estrogen-related receptors, membrane-bound estrogen-receptors, and interaction with targets in the cytosol resulting in activation of the Src/Ras/Erk pathway or modulation of nitric oxide. In addition, changes in metabolism of endogenous hormones, cross-talk between genomic and nongenomic pathways, cross talk with estrogen receptors after binding on other receptors, interference with feedback regulation and neuroendocrine cells, changes in DNA methylation or histone modifications, and genomic instability by interference with the spindle figure can play a role. Also it was found that effects of receptor activation can differ in function of the ligand.