Flame retardant tris(1,3-dichloro-2-propyl)phosphate (TDCPP) toxicity is attenuated by N-acetylcysteine in human kidney cells

Nephrotoxicity of organophosphate flame retardants in patients with chronic kidney disease: A 2-year longitudinal study

Humans are extensively exposed to organophosphate flame retardants (OPFRs), an emerging group of organic contaminants with potential nephrotoxicity. Nevertheless, the estimated daily intake (EDI) and prognostic impacts of OPFRs have not been assessed in individuals with chronic kidney disease (CKD). In this 2-year longitudinal study of 169 patients with CKD, we calculated the EDIs of five OPFR triesters from urinary biomonitoring data of their degradation products and analyzed the effects of OPFR exposure on adverse renal outcomes and renal function deterioration. Our analysis demonstrated universal OPFR exposure in the CKD population, with a median EDIΣOPFR of 360.45 ng/kg body weight/day (interquartile range, 198.35-775.94). Additionally, our study revealed that high tris(2-chloroethyl) phosphate (TCEP) exposure independently correlated with composite adverse events and composite renal events (hazard ratio [95 % confidence interval; CI]: 4.616 [1.060-20.096], p = 0.042; 3.053 [1.075-8.674], p = 0.036) and served as an independent predictor for renal function deterioration throughout the study period, with a decline in estimated glomerular filtration rate of 4.127 mL/min/1.73 m2 (95 % CI, -8.127--0.126; p = 0.043) per log ng/kg body weight/day of EDITCEP. Furthermore, the EDITCEP and EDIΣOPFR were positively associated with elevations in urinary 8-hydroxy-2'-deoxyguanosine and kidney injury molecule-1 during the study period, indicating the roles of oxidative damage and renal tubular injury in the nephrotoxicity of OPFR exposure. To conclude, our findings highlight the widespread OPFR exposure and its possible nephrotoxicity in the CKD population.

Association of co-exposure to organophosphate esters and per- and polyfluoroalkyl substances and mixture with cardiovascular-kidney-liver-metabolic biomarkers among Chinese adults

BACKGROUND

Organophosphate esters (OPEs) and Per- and polyfluoroalkyl substances (PFAS) are ubiquitous environmental contaminants with common exposure sources, leading to their widespread presence in human body. However, evidence on co-exposure to OPEs and PFAS and its impact on cardiovascular-kidney-liver-metabolic biomarkers remains limited.

METHODS

In this cross-sectional study, 467 adults were enrolled from January to May 2022 during physical visits in Shijiazhuang, Hebei province. Eleven types of OPEs and twelves types of PFAS were detected, among which eight OPEs and six PFAS contaminants were detected in more than 60% of plasma samples. Seventeen biomarkers were assessed to comprehensively evaluate the cardiovascular-kidney-liver-metabolic function. Multiple linear regression, multipollutant models with sparse partial least squares, and Bayesian kernel machine regression (BKMR) models were applied to examine the associations of individual OPEs and PFAS and their mixtures with organ function and metabolism, respectively.

RESULTS

Of the over 400 exposure-outcome associations tested when modelling, we observed robust results across three models that perfluorohexanoic acid (PFHxS) was significantly positively associated with alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (TBIL), and indirect bilirubin (IBIL). Perfluorononanoic acid was significantly associated with decreased AST/ALT and increased very-low-density lipoprotein cholesterol levels. Besides, perfluorodecanoic acid was correlated with increased high lipoprotein cholesterol and perfluoroundecanoic acid was consistently associated with lower glucose level. BKMR analysis showed that OPEs and PFAS mixtures were positively associated with IBIL and TBIL, among which PFHxS was the main toxic chemicals.

CONCLUSIONS

Our findings suggest that exposure to OPEs and PFAS, especially PFHxS and PFNA, may disrupt organ function and metabolism in the general population, providing insight into the potential pathophysiological mechanisms of OPEs and PFAS co-exposure and chronic diseases.

Tris(1,3-dichloro-2-propyl) phosphate-induced cytotoxicity and its associated mechanisms in human A549 cells

Tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) is a widely used organophosphorus flame retardant and has been detected in various environmental matrices including indoor dust. Inhalation of indoor dust is one of the most important pathways for human exposure to TDCIPP. However, its adverse effects on human lung cells and potential impacts on respiratory toxicity are largely unknown. In the current study, human non-small cell carcinoma (A549) cells were selected as a cell model, and the effects of TDCIPP on cell viability, cell cycle, cell apoptosis, and underlying molecular mechanisms were investigated. Our data indicated a concentration-dependent decrease in the cell viability of A549 cells after exposure to TDCIPP for 48 h, with half lethal concentration (LC50) being 82.6 µM. In addition, TDCIPP caused cell cycle arrest mainly in the G0/G1 phase by down-regulating the mRNA expression of cyclin D1, CDK4, and CDK6, while up-regulating the mRNA expression of p21 and p27. In addition, cell apoptosis was induced via altering the expression levels of Bcl-2, BAX, and BAK. Our study implies that TDCIPP may pose potential health risks to the human respiratory system and its toxicity should not be neglected.

TDCPP and TiO2 NPs aggregates synergistically induce SH-SY5Y cell neurotoxicity by excessive mitochondrial fission and mitophagy inhibition

Tris (1,3-dichloro-2-propyl) phosphate (TDCPP), a halogen-containing phosphorus flame retardant, is widely used and has been shown to possess health risks to humans. The sustained release of artificial nanomaterials into the environment increases the toxicological risks of their coexisting pollutants. Nanomaterials may seriously change the environmental behavior and fate of pollutants. In this study, we investigated this combined toxicity and the potential mechanisms of toxicity of TDCPP and titanium dioxide nanoparticles (TiO2 NPs) aggregates on human neuroblastoma SH-SY5Y cells. TDCPP and TiO2 NPs aggregates were exposed in various concentration combinations, revealing that TDCPP (25 μg/mL) reduced cell viability, while synergistic exposure to TiO2 NPs aggregates exacerbated cytotoxicity. This combined exposure also disrupted mitochondrial function, leading to dysregulation in the expression of mitochondrial fission proteins (DRP1 and FIS1) and fusion proteins (OPA1 and MFN1). Consequently, excessive mitochondrial fission occurred, facilitating the translocation of cytochrome C from mitochondria to activate apoptotic signaling pathways. Furthermore, exposure of the combination of TDCPP and TiO2 NPs aggregates activated upstream mitochondrial autophagy but disrupted downstream Parkin recruitment to damaged mitochondria, preventing autophagosome-lysosome fusion and thereby disrupting mitochondrial autophagy. Altogether, our findings suggest that TDCPP and TiO2 NPs aggregates may stimulate apoptosis in neuronal SH-SY5Y cells by inducing mitochondrial hyperfission and inhibiting mitochondrial autophagy.

Tris(1,3-dichloro-2-propyl) phosphate disrupts cellular metabolism within human embryonic kidney (HEK293) cells

Tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) is a widely used, additive flame retardant that migrates from end-use products, leading to ubiquitous exposure of humans around the world. However, little is known about whether TDCIPP disrupts the physiology of human embryonic cells. Therefore, the objective of this study was to determine whether TDCIPP alters cell viability, cellular metabolism, cytosine methylation, and reactive oxygen species (ROS) levels within human embryonic kidney (HEK293) cells. Relative to vehicle controls, TDCIPP (0.015-0.1225 µM) resulted in a concentration-dependent increase in cell viability, a finding that was driven by an increase in relative ATP abundance. Interestingly, TDCIPP (0.061-0.98 µM) increased the rate of glycolysis - an adaptive mechanism consistent with the Warburg effect exhibited by tumorigenic cells. Moreover, relative to vehicle-treated cells, TDCIPP (0.245-15.63 µM) exposure for 48 h (but not 24 h) resulted in a significant, concentration-dependent decrease in ROS in situ, and TDCIPP (0.245 µM) exposure significantly increased carnosine within the histidine metabolism pathway. However, TDCIPP did not affect global 5-methylcytosine (5-mC) methylation (0.015-15.63 µM), cell membrane integrity (0.061-0.98 µM), nor the abundance of mitochondria (0.061-1.95 µM). Overall, our findings with TDCIPP point to a novel mechanism of action that may be relevant to human embryonic stem cells.

Comparison between pollutants found in breast milk and infant formula in the last decade: A review

Since ancient times, breastfeeding has been the fundamental way of nurturing the newborn. The benefits of breast milk are widely known, as it is a source of essential nutrients and provides immunological protection, as well as developmental benefits, among others. However, when breastfeeding is not possible, infant formula is the most appropriate alternative. Its composition meets the nutritional requirements of the infant, and its quality is subject to strict control by the authorities. Nonetheless, the presence of different pollutants has been detected in both matrices. Thus, the aim of the present review is to make a comparison between the findings in both breast milk and infant formula in terms of contaminants in the last decade, in order to choose the most convenient option depending on the environmental conditions. For that, the emerging pollutants including metals, chemical compounds derived from heat treatment, pharmaceutical drugs, mycotoxins, pesticides, packaging materials, and other contaminants were described. While in breast milk the most concerning contaminants found were metals and pesticides, in infant formula pollutants such as metals, mycotoxins, and packaging materials were the most outstanding. In conclusion, the convenience of using a feeding diet based on breast milk or either infant formula depends on the maternal environmental circumstances. However, it is important to take into account the immunological benefits of the breast milk compared to the infant formula, and the possibility of using breast milk in combination with infant formula when the nutritional requirements are not fulfilled only with the intake of breast milk. Therefore, more attention should be paid in terms of analyzing these conditions in each case to be able to make a proper decision, as it will vary depending on the maternal and newborn environment.

Microplastics Derived from Food Packaging Waste-Their Origin and Health Risks

Plastics are commonly used for packaging in the food industry. The most popular thermoplastic materials that have found such applications are polyethylene (PE), polypropylene (PP), poly(ethylene terephthalate) (PET), and polystyrene (PS). Unfortunately, most plastic packaging is disposable. As a consequence, significant amounts of waste are generated, entering the environment, and undergoing degradation processes. They can occur under the influence of mechanical forces, temperature, light, chemical, and biological factors. These factors can present synergistic or antagonistic effects. As a result of their action, microplastics are formed, which can undergo further fragmentation and decomposition into small-molecule compounds. During the degradation process, various additives used at the plastics' processing stage can also be released. Both microplastics and additives can negatively affect human and animal health. Determination of the negative consequences of microplastics on the environment and health is not possible without knowing the course of degradation processes of packaging waste and their products. In this article, we present the sources of microplastics, the causes and places of their formation, the transport of such particles, the degradation of plastics most often used in the production of packaging for food storage, the factors affecting the said process, and its effects.

The associations between renal disease severity and exposure to organophosphate flame retardants in patients with chronic kidney disease

Organophosphate flame retardants (OPFRs) are emerging and widespread environmental pollutants with potential health hazards, including nephrotoxicity. However, the exposure patterns and nephrotoxic potential of OPFRs are yet to be investigated in patients with chronic kidney disease (CKD). We conducted a cross-sectional study involving 166 patients with CKD stratified by estimated glomerular filtration rate (eGFR) and severity of proteinuria. The urinary concentrations of 10 OPFR compounds were measured to evaluate the exposure patterns. Clinical and urinary OPFR profiles were compared among subgroups to identify whether the OPFR compounds were independently correlated with eGFR and proteinuria. Additionally, lifestyle factors were compared among subgroups stratified by median concentrations of urinary OPFR compounds associated with renal disease severity. This study revealed universal exposure to OPFRs in the CKD population, with an overall urinary detection rate of 98.80 %. Furthermore, after adjusting for covariates, the urinary concentration of bis(2-chloroethyl) phosphate (BCEP) was identified as an independent predictor of lower eGFR (low vs high eGFR, odds ratio (OR) (95 % confidence interval (CI)), 1.761 (1.032-3.005) per log μg/g creatinine, p = 0.038), and the urinary concentration of bis(2-butoxyethyl) phosphate (BBOEP) was independently correlated with overt proteinuria in CKD patients (with vs without overt proteinuria, OR (95 % CI), 1.813 (1.065-3.086) per log μg/g creatinine, p = 0.028). Moreover, frequent seafood consumption was negatively correlated with urinary BCEP concentration (high vs low BCEP, OR (95 % CI), 0.455 (0.228-0.908), p = 0.025), and age was inversely associated with urinary BBOEP concentration (high vs low BBOEP, OR (95 % CI), 0.968 (0.937-0.999) per year, p = 0.048). In conclusion, our investigation highlights the extensive exposure to OPFRs and the independent association between renal disease severity and urinary BCEP/BBOEP concentrations in the CKD population, indicating the nephrotoxic potential of these pollutants.

Organophosphate flame retardant TDCPP: A risk factor for renal cancer?

Tris (1,3-dichloro-2-propyl) phosphate (TDCPP), a chlorinated organophosphate flame retardants(OPFRs), is widely used in a range of plastic foams, resins, and latexes. It can be detected in human tissues, including urine, and milk. Recent research has suggested that TDCPP has neurotoxic, reproductive, and potentially carcinogenic. In our study, we proposed a novel method for predicting the gene associated with tumor-compound interactions. We firstly used The Comparative Toxicogenomics Database (CTD) and downloaded potentially interactive genes about TDCPP in renal carcinoma. Gene expression data and the corresponding clinical information of the Kidney renal clear cell cancer (KIRC) patients were obtained from The Cancer Genome Atlas database (TCGA). Data from normal people in The Genotype-Tissue Expression (GTEx) databases was used to supplement the calculations. After being predicted by PharmMapper database, and validated by Gene Ontology and Kyoto Encyclopedia of Genes and Genomes, 25 genes were selected to construct protein-protein interaction network analysis. The prognostic value of these genes was evaluated with Kaplan-Meier analysis, and four interactive genes were selected. Gene set variation analysis and drug-target binding prediction proved the hub gene has a potential relationship with renal clear cell carcinoma. We then used the ChEA3 (Chip-X Enrichment Analysis, Version 3) database to predict the upstream of these interactive genes. Molecular docking was used to predict the binding of these transcription factors to TDCPP and interactive genes to TDCPP. Moreover, in cell lines and in vivo experiments demonstrated the cancer-promoting effect of TDCPP. The expression of the interactive genes was verified by qPCR and Western blot. Combining binding energy and qPCR results, we choose EPAS1 to verify its function in renal carcinoma cell lines. Our study provides a novel method to predict the potential interactive genes between TDCPP and renal cancer, which may reveal potential targets for the treatment and prevention of diseases.

Terrigenous export and ocean currents' diffusion of organophosphorus flame retardants along China's adjacent seas

High demands for but strict regulatory measures on Organophosphorus Flame Retardants (OPFRs) have resulted in mainland China transitioning from the region that imports OPRFs to one that exports these substances. Simultaneously, large quantities of terrigenous OPFRs have been exported to adjacent seas by the major river systems, particularly the Yangtze River. This study examined the presence of ten OPFRs in China's adjacent seas. High levels of OPFRs were observed in seas south of mainland China, with Tris (2-chloroethyl) phosphate (TCEP) and Tris (1,3-dichloro-2-propyl) phosphate (TDCPP) dominant. The terrigenous OPFRs were redistributed by the ocean surface currents, with OPFRs tending to accumulate in regions with lower current speed. The producers of OPFRs are mainly distributed along the Haihe, Yellow, and Yangtze river systems. The application of OPFRs to electric vehicle charging stations, charging connectors, and 5G infrastructure in the Chinese mainland will likely drive rapid growth in OPFR related industry in the future. The diffusion trend map of OPFR indicated that the Bohai Sea and the central northern Yellow Sea are at high risk of ecological damage in the spring. The offshore region of the north of the South China Sea tended to aggregate more OPFRs in summer. Regions of the OPFR aggregation effect were at a higher risk of ecological damage.

The influence of PM2.5 exposure on kidney diseases

The harm of air pollution to public health has become a research hotspot, especially atmospheric fine-particulate matter (PM_2.5). In recent years, epidemiological investigations have confirmed that PM_2.5 is closely related to chronic kidney disease and membranous nephropathy Basic research has demonstrated that PM_2.5 has an impact on the normal function of the kidneys through accumulation in the kidney, endothelial dysfunction, abnormal renin-angiotensin system, and immune complex deposition. Moreover, the mechanism of PM_2.5 damage to the kidney involves inflammation, oxidative stress, apoptosis, DNA damage, and autophagy. In this review, we summarized the latest developments in the effects of PM_2.5 on kidney disease in human and animal studies, so as to provide new ideas for the prevention and treatment of kidney disease.

Organophosphorus Flame Retardant TDCPP Displays Genotoxic and Carcinogenic Risks in Human Liver Cells

Tris(1,3-Dichloro-2-propyl)phosphate (TDCPP) is an organophosphorus flame retardant (OPFR) widely used in a variety of consumer products (plastics, furniture, paints, foams, and electronics). Scientific evidence has affirmed the toxicological effects of TDCPP in in vitro and in vivo test models; however, its genotoxicity and carcinogenic effects in human cells are still obscure. Herein, we present genotoxic and carcinogenic properties of TDCPP in human liver cells (HepG2). 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) and neutral red uptake (NRU) assays demonstrated survival reduction in HepG2 cells after 3 days of exposure at higher concentrations (100-400 μM) of TDCPP. Comet assay and flow cytometric cell cycle experiments showed DNA damage and apoptosis in HepG2 cells after 3 days of TDCPP exposure. TDCPP treatment incremented the intracellular reactive oxygen species (ROS), nitric oxide (NO), Ca2+ influx, and esterase level in exposed cells. HepG2 mitochondrial membrane potential (ΔΨm) significantly declined and cytoplasmic localization of P53, caspase 3, and caspase 9 increased after TDCPP exposure. qPCR array quantification of the human cancer pathway revealed the upregulation of 11 genes and downregulation of two genes in TDCPP-exposed HepG2 cells. Overall, this is the first study to explicitly validate the fact that TDCPP bears the genotoxic, hepatotoxic, and carcinogenic potential, which may jeopardize human health.

Proteomic analysis using isobaric tags for relative and absolute quantification technology reveals mechanisms of toxic effects of tris (1,3-dichloro-2-propyl) phosphate on RAW264.7 macrophage cells

Tris (1,3-dichloro-2-propyl) phosphate (TDCIPP) is one of the most commonly used organophosphorus flame retardants. Immuno-toxicity induced by TDCIPP is becoming of increasing concern. However, effects of TDCIPP on immune cells and mechanisms resulting in those effects are poorly understood. In this study, it was determined, for the first time, by use of isobaric tags for relative and absolute quantification (iTRAQ) based proteomic techniques expression of global proteins in RAW264.7 cells exposed to 10 μM TDCIPP. A total of 180 significantly differentially expressed proteins (DEPs) were identified. Of these, 127 were up-regulated and 53 were down-regulated. The DEPs associated with toxic effects of TDCIPP were then screened by use of Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes for enrichment analysis. Results showed that these DEPs were involved in a number of pathways including apoptosis, DNA damage, cell cycle arrest, immune-toxicity, and signaling pathways, such as the Toll-like receptor, PPAR and p53 signaling pathways. The complex regulatory relationships between different DEPs, which might play an important role in cell death were also observed in the form of a protein-protein interaction network. Meanwhile, mitochondrial membrane potential (MMP) in RAW264.7 cells after TDCIPP treatment was also analyzed, the collapse of the MMP was speculated to play an important role in TDCIPP induced apoptosis. Moreover, some of the important regulator proteins discovered in this study, such as Chk1, Aurora A, would provide novel insight into the molecular mechanisms involved in toxic responses to TDCIPP.

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.

The toxicity effects and mechanisms of tris(1,3-dichloro-2-propyl) phosphate (TDCPP) and its ecological risk assessment for the protection of freshwater organisms

Tris (1,3-dichloro-2-propyl) phosphate (TDCPP) is a type halogenated organophosphate flame retardants (OPFRs), which has been identified as contaminants of emerging concern (CECs). The use and production of OPFRs began to increase gradually when brominated flame retardants (BFRs) were banned. Halogenated OPFRs, especially TDCPP have been considered to lead to mutagenicity and carcinogenesis and major concerns have been raised regarding their toxicity. In this study, the toxicity effects and mechanisms of TDCPP were summarized and ecological risk assessment was made regarding its potential impact on freshwater organisms. TDCPP has been widely detected in ecosystems throughout the world, with observed toxicity effects on both humans and freshwater organisms. Inhalation of the dust was found to be the main exposure for humans. TDCPP could be metabolized in the human body, and medium stability was achieved in human body with the main metabolite BDCPP. Aside from mutagenicity and carcinogenesis, TDCPP was also found to have the potential for endocrine disruption and impairing the human reproductive system. Furthermore, this study reviewed the results of previous toxicity experiments, including acute toxicity, growth and development toxicity, neurotoxicity, and hepatotoxicity in freshwater organisms. Risk assessment was made using the safety threshold method by comparing the toxicity data with the exposure data in freshwater. HC₅ (hazardous concentration for 5% of organisms) derived based on traditional endpoints of acute toxicity LC₅₀ (median lethal concentration) or EC₅₀ (concentration for 50% of maximal effect) was 877 μg/L. This value was much higher than the exposure concentration levels in the surface water with EXD₉₀ (exposure data with cumulative probability 90%) of 65.22 ng/L. However, based on the growth and development toxicity data, the derived HC₅ was 33.33 ng/L and the calculated MOS (margin of safety) was below 1. Therefore, the results validated the fact that the ecological risk of TDCPP could not be neglected for its growth and development toxicity.

The interactions of diet-induced obesity and organophosphate flame retardant exposure on energy homeostasis in adult male and female mice

Previously, sex-dependent alterations in energy homeostasis were reported in adult mice fed a standard chow attributed to exposure to a mixture of organophosphate flame retardants (OPFRs) via estrogen receptors (ERα). In this study, adult male and female mice (C57BL/6J; Taconic) were treated with the same mixture of OPFRs (1 mg/kg each of tricresyl phosphate (TCP), triphenyl phosphate (TPP), and tris(1-3-dichloro-2propyl)phosphate (TDCPP)) for 7 weeks on a low-fat diet (LFD, 10% kcal fat) or a high fat (HFD, 45% kcal fat) in a diet-induced obesity model. Consistent with our previous observations, OPFRs altered weight gain in males, differentially with diet, while females remained unaffected. OPFR treatment also revealed sex-dependent perturbations in metabolic activity. During the night (approximately 0100-0400 hr), males exhibited elevated activity and oxygen consumption, while in females these parameters were decreased, irrespective of diet. OPFR disrupted feeding behavior and abolished diurnal water intake patterns in females while increasing nighttime fluid consumption in males. Despite no marked effect of OPFRs on glucose or insulin tolerance, OPFR treatment altered circulating insulin and leptin in females and ghrelin in males. Data indicate that adult OPFR exposure might influence, and perhaps exacerbate, the effects of diet-induced obesity in adult mice by altering activity, ingestive behavior, and metabolism.

Combined exposure to phthalate esters and phosphate flame retardants and plasticizers and their associations with wheeze and allergy symptoms among school children

BACKGROUND

Phthalate esters and phosphate flame retardants and plasticizers (PFRs) are both used as plasticizers and are commonly detected in indoor environments. Although both phthalates and PFRs are known to be associated with children's wheeze and allergic symptoms, there have been no previous studies examining the effects of mixtures of these exposures.

OBJECTIVES

To investigate the association between exposure to mixtures of phthalate esters and PFRs, and wheeze and allergic symptoms among school-aged children.

METHODS

A total of 128 elementary school-aged children were enrolled. Metabolites of 3 phthalate esters and 7 PFRs were measured in urine samples. Parent-reported symptoms of wheeze, rhinoconjunctivitis, and eczema were evaluated using the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire. In the primary model, we created a phthalate ester and PFR mixture exposure index, and estimated odds ratios (ORs) using weighted quantile sum (WQS) regression and quantile g (qg)-computation. The two highest chemicals according to qg-computation weight %s were combined to create a combination high × high exposure estimate, with ORs calculated using the "low × low" exposure group as the reference category. Concentrations of each metabolite were corrected by multiplying this value by the sex- and body size-Standardised creatinine concentration and dividing by the observed creatinine value. All models were adjusted for sex, grade, dampness index and annual house income.

RESULTS

The odds ratio of rhinoconjunctivitis for the association between exposure to chemical mixtures according to the WQS index positive models was; OR = 2.60 (95% confidence interval [CI]: 1.38-5.14). However, wheeze and eczema of the WQS index positive model, none of the WQS index negative models or qg-computation result yielded statistically significant results. Combined exposure to the two highest WQS weight %s of "high-high" ΣTCIPP and ΣTPHP was associated with an increased prevalence of rhino-conjunctivitis, OR = 5.78 (1.81-18.43) to the "low × low" group.

CONCLUSIONS

Significant associations of mixed exposures to phthalates and PFRs and increased prevalence of rhinoconjunctivitis was found among elementary school-aged children in the WQS positive model. Mixed exposures were not associated with any of allergic symptoms in the WQS negative model or qg-computation approach. However, the combined effects of exposure to two PFRs suggested an additive and/or multiplicative interaction, potentially increasing the prevalence of rhinoconjunctivitis. A further study with a larger sample size is needed to confirm these results.

Pesticides, cognitive functions and dementia: A review

Pesticides are widely-used chemicals commonly applied in agriculture for the protection of crops from pests. Depending on the class of pesticides, the specific substances may have a specific set of adverse effects on humans, especially in cases of acute poisoning. In past years, evidence regarding sequelae of chronic, low-level exposure has been accumulating. Cognitive impairment and dementia heavily affect a person's quality of life and scientific data has been hinting towards an association between them and antecedent chronic pesticide exposure. Here, we reviewed animal and human studies exploring the association between pesticide exposure, cognition and dementia. Additionally, we present potential mechanisms through which pesticides may act neurotoxically and lead to neurodegeneration. Study designs rarely presented homogeneity and the estimation of the exposure to pesticides has been most frequently performed without measuring the synergic effects and the possible interactions between the toxicants within mixtures, and also overlooking low exposures to environmental toxicants. It is possible that a Real-Life Risk Simulation approach would represent a robust alternative for future studies, so that the safe exposure limits and the net risk that pesticides confer to impaired cognitive function can be examined. Previous studies that evaluated the effect of low dose chronic exposure to mixtures of pesticides and other chemicals intending to simulate real life exposure scenarios showed that hormetic neurobehavioral effects can appear after mixture exposure at doses considered safe for individual compounds and these effects can be exacerbated by a coexistence with specific conditions such as vitamin deficiency. However, there is an overall indication, derived from both epidemiologic and laboratory evidence, supporting an association between exposure to neurotoxic pesticides and cognitive dysfunction, dementia and Alzheimer's disease.

Chlorinated phosphorus flame retardants exert oxidative damage to SMMC-7721 human hepatocarcinoma cells

Chlorinated phosphorus flame retardants are organic pollutants widely distributed in the environment. However, there is still a lack of understanding of the toxicity mechanism of chlorinated phosphorus flame retardants at the molecular level. Tris (1, 3-dichloroisopropyl) phosphate (TDCPP), tris (2-chloropropyl) phosphate (TCPP) and tris (2-chloroethyl) phosphate (TCEP) were used as typical representatives of chlorinated phosphorus flame retardants to evaluate their cytotoxicity as well as changes in the expression of the enzymes lactate dehydrogenase (LDH), superoxide dismutase (SOD), and catalase (CAT), which will be meaningful for an in-depth study of the toxicity mechanism of TDCPP, TCPP and TCEP. The results showed that the three chemicals reduced cell viability over a period of 24 h. The exposure increased extracellular levels of lactate dehydrogenase and decreased intracellular levels of superoxide dismutase and catalase in a concentration-dependent manner. Expression of the SOD and CAT genes were down-regulated indicating that the SMMC-7721 human hepatocarcinoma cells may experience oxidative damage as a result of exposure to the three chemicals. The expression of the Bax apoptosis protein was up-regulated and the Bcl-2 apoptosis protein was down-regulated, suggesting that the three chemicals may cause functional defects, damage the cell structure and promote apoptosis. The results from this study should provide the basis for a detailed investigation of the ecological toxicity of chlorinated phosphorus flame retardants.

Urinary metabolites of organophosphate esters (OPEs) are associated with chronic kidney disease in the general US population, NHANES 2013-2014

Organophosphate esters (OPEs) have been widely used in building materials and consumer products as flame retardants and plasticizers. In vitro studies have suggested adverse effects of OPEs on the kidney. Despite accumulating evidence indicating widespread exposure to OPEs, their association with renal function in humans has not been evaluated. This study aims to investigate the association between OPEs exposure and chronic kidney disease (CKD) among the general US adult population by employing data from the US National Health and Nutrition Examination Survey (NHANES) 2013-2014. Among 1578 adults who were not currently pregnant, the associations of the urinary OPE metabolites with two CKD-related parameters, i.e., estimated glomerular filtration rate (eGFR) and albumin-to-creatinine ratio (ACR), and CKD were assessed. To account for urine dilution, in addition to conventional creatinine-adjustment, covariate-adjusted creatinine standardization, which controls for potential confounding by kidney function, was employed. Multi-pollutant models were also constructed to verify the associations observed in the models on individual OPE metabolites. The urinary bis(2-chloroethyl) phosphate (BCEP) level was negatively associated with eGFR only with the covariate-adjusted standardization method, but not with the conventional creatinine adjustment. In addition, both bis(1,3-dichloro-2-propyl) phosphate (BDCIPP) and di-n-butyl phosphate (DNBP) were positively associated with the ACR, regardless of methods of urine dilution adjustment. These three compounds were also associated with CKD. Following adjusting urine dilution with the covariate-adjusted standardization method, the association became more evident. Moreover, similar results were observed in the secondary analysis with the multi-pollutant models. Among the US general population, several OPEs were identified as potential chemical determinants of CKD. Experimental studies are warranted to understand the potential mechanisms underlying this observation.

Acetylcysteine-decorated Prussian blue nanoparticles for strong photothermal sterilization and focal infection treatment

The major challenge in bacterial infection in clinical settings is the development of antimicrobial materials in the treatment of drug-resistant bacteria. Herein, we report a new strategy for efficient near-infrared radiation (NIR) photothermal sterilization and focal infection treatment by acetylcysteine-modified Prussian blue nanoparticles (AC-PB). Specifically, AC-PB is fabricated as a multifunctional therapeutic agent via a co-precipitation approach, where PB acts as an effective photothermal agent and AC could prevent the formation of bacteria cluster in biofilms and the bacterial adhesion on tissues to reduce the secretion of mucus and improve the efficacy. AC-PB shows strong synergistic photothermal sterilization ability in a concentration-dependent manner by using 980 nm NIR laser. 50 μg/mL of AC-PB can eliminate up to 74% of Gram-positive Staphylococcus aureus and up to 75% of Gram-negative Escherichia coli, while irradiation of 980 nm is minimally cytotoxic to mammalian cells. The NIR radiation can be efficiently converted into local heat by subcutaneous injection of AC-PB to kill bacteria effectively in vivo to treat a focal infection. The antibacterial mechanism suggests that AC can destroy bacteria-based biofilms, while the photothermal effect driven by NIR may break the lipids on cellular membrane. Thus, this work may provide a promising strategy for highly effective eradication of bacteria in clinics.

DNA damage and methylation induced by organophosphate flame retardants: Tris(2-chloroethyl) phosphate and tris(1-chloro-2-propyl) phosphate in human peripheral blood mononuclear cells

Phosphorus flame retardants are a group of chemicals that are used to slow or prevent the spread of fire. These compounds have been detected in different environments including human organism. In the present study, we have investigated DNA-damaging potential and effect on DNA methylation of tris(2-chloroethyl) phosphate (TCEP) and tris(1-chloro-2-propyl) phosphate (TCPP) in human peripheral blood mononuclear cells (PBMCs). In order to determine DNA damage and repair, the alkaline and neutral versions of the comet assay were used. The level of DNA methylation was determined with specific antibodies against methylated DNA. PBMCs were exposed to TCEP and TCPP at the concentrations in the range of 1-1000 µM for 24 h. We have observed that TCEP and TCPP induced DNA damage-DNA breaks and alkali-labile sites. All DNA damages were effectively repaired during 120-min repair incubation. The results have also shown that TCEP and TCPP decreased the level of DNA methylation in PBMCs. In the case of TCEP, this effect was observed at a very low concentration of 1 µM.

Associations between allergic symptoms and phosphate flame retardants in dust and their urinary metabolites among school children

BACKGROUND

Phosphate flame retardants (PFRs) are ubiquitously detected in indoor environments. Despite increasing health concerns pertaining to PFR exposure, few epidemiological studies have examined PFR exposure and its effect on children's allergies.

OBJECTIVES

To investigate the association between PFRs in house dust, their metabolites in urine, and symptoms of wheeze and allergies among school-aged children.

METHODS

A total of 128 elementary school-aged children were enrolled. House dust samples were collected from upper-surface objects. Urine samples were collected from the first morning void. Levels of 11 PFRs in dust and 14 PFR metabolites in urine were measured. Parent-reported symptoms of wheeze, rhinoconjunctivitis, and eczema were evaluated using the International Study of Asthma and Allergies in Childhood questionnaire. The odds ratios (ORs) of the Ln transformed PFR concentrations and categorical values were calculated using a logistic regression model adjusted for sex, grade, dampness index, annual house income, and creatinine level (for PFR metabolites only).

RESULTS

The prevalence rates of wheeze, rhinoconjunctivitis, and eczema were 22.7%, 36.7%, and 28.1%, respectively. A significant association between tris(1,3-dichloroisopropyl) phosphate (TDCIPP) in dust and eczema was observed: OR (95% confidence interval), 1.44 (1.13-1.82) (>limit of detection (LOD) vs <LOD). The ORs for rhinoconjunctivitis (OR = 5.01 [1.53-16.5]) and for at least one symptom of allergy (OR = 3.87 [1.22-12.3]) in the 4th quartile of Σtris(2-chloro-isopropyl) phosphate (TCIPP) metabolites was significantly higher than those in the 1st quartile, with significant p-values for trend (P_trend) (0.013 and 0.024, respectively). A high OR of 2.86 (1.04-7.85) (>LOD vs <LOD) was found for hydroxy tris(2-butoxyethyl) phosphate (TBOEP)-OH and eczema. OR of the 3rd tertile of bis (1,3-dichloro-2-propyl) phosphate (BDCIPP) was higher than the 1st tertile as a reference for at least one symptom (OR = 3.91 [1.25-12.3]), with a significant P_trend = 0.020.

CONCLUSIONS

We found that TDCIPP in house dust, and metabolites of TDCIPP, TBOEP and TCIPP were associated with children's allergic symptoms. Despite some limitations of this study, these results indicate that children's exposure to PFR may impact their allergic symptoms.

Organophosphate flame retardants and plasticizers in indoor dust, air and window wipes in newly built low-energy preschools

The construction of extremely airtight and energy efficient low-energy buildings is achieved by using functional building materials, such as age-resistant plastics, insulation, adhesives, and sealants. Additives such as organophosphate flame retardants (OPFRs) can be added to some of these building materials as flame retardants and plasticizers. Some OPFRs are considered persistent, bioaccumulative and toxic. Therefore, in this pilot study, the occurrence and distribution of nine OPFRs were determined for dust, air, and window wipe samples collected in newly built low-energy preschools with and without environmental certifications. Tris(1,3-dichloroisopropyl) phosphate (TDCIPP) and triphenyl phosphate (TPHP) were detected in all indoor dust samples at concentrations ranging from 0.014 to 10μg/g and 0.0069 to 79μg/g, respectively. Only six OPFRs (predominantly chlorinated OPFRs) were detected in the indoor air. All nine OPFRs were found on the window surfaces and the highest concentrations, which occurred in the reference preschool, were measured for 2-ethylhexyl diphenyl phosphate (EHDPP) (maximum concentration: 1500ng/m²). Interestingly, the OPFR levels in the environmental certified low-energy preschools were lower than those in the reference preschool and the non-certified low-energy preschool, probably attributed to the usage of environmental friendly and low-emitting building materials, interior decorations, and consumer products.