Assessment of the endocrine-disrupting effects of short-chain chlorinated paraffins in in vitro models

Effects of environmentally relevant concentration of short-chain chlorinated paraffins on BV2 microglia activation and lipid metabolism, implicating altered neurogenesis

Short-chain chlorinated paraffins (SCCPs), a class of persistent organic pollutants, have been found to cause diverse organ and systemic toxicity. However, little is known about their neurotoxic effects. In this study, we exposed BV2, a mouse microglia cell line, to environmentally relevant concentration of SCCPs (1 μg/L, 10 μg/L, 100 μg/L) for 24 h to investigate their impacts on the nervous system. Our observations revealed that SCCPs induced the activation of BV2 microglia, as indicated by altered morphology, stimulated cell proliferation, enhanced phagocytic and migratory capabilities. Analysis at the mRNA level confirmed the activation status, with the downregulation of TMEM119 and Tgfbr1, and upregulation of Iba1 and CD11b. The upregulated expression of genes such as cenpe, mki67, Axl, APOE and LPL also validated alterations in cell functions. Moreover, BV2 microglia presented an M2 alternative phenotype upon SCCPs exposure, substantiated by the reduction of NF-κB, TNF-α, IL-1β, and the elevation of TGF-β. Additionally, SCCPs caused lipid metabolic changes in BV2 microglia, characterized by the upregulations of long-chain fatty acids and acylcarnitines, reflecting an enhancement of β-oxidation. This aligns with our findings of increased ATP production upon SCCPs exposure. Intriguingly, cell activation coincided with elevated levels of omega-3 polyunsaturated fatty acids. Furthermore, activated microglial medium remarkably altered the proliferation and differentiation of mouse neural stem cells. Collectively, exposure to environmentally relevant concentrations of SCCPs resulted in activation and lipid metabolic alterations in BV2 microglia, potentially impacting neurogenesis. These findings provide valuable insights for further research on the neurotoxic effect of SCCPs.

In vitro assessment of potential endocrine disrupting activities of chlorinated paraffins of various chain lengths

The production of chlorinated paraffins (CPs) has risen in the past two decades due to their versatile industrial applications. Consequently, CPs are now widely detected in human food sources, the environment, and in human matrices such as serum, the placenta and breast milk. This raises concern about prenatal and postnatal exposure. While some studies suggest that certain short-chained CPs (SCCPs) may have endocrine disrupting properties, knowledge about potential endocrine disrupting potential of medium- (MCCP) and long-chained CPs (LCCPs) remains relativity sparse. Here, we used a panel of in vitro assays to investigate seven pure CPs and two technical mixtures of CPs. These varied in chain length and, chlorination degree. The in vitro panel covered androgen, estrogen, and retinoic acid receptor activities, transthyretin displacement, and steroidogenesis. One of the SCCPs inhibited androgen receptor (AR) activity. All SCCPs induced estrogen receptor (ER) activity. Some SCCPs and MCCPs increased 17β-estradiol levels in the steroidogenesis assay, though not consistently across all substances in these groups. SCCPs exhibited the most pronounced effects in multiple in vitro assays, while the tested LCCPs showed no effects. Based on our results, some CPs can have endocrine disrupting potential in vitro. These findings warrant further examinations to ensure that CPs do not cause issues in intact organisms, including humans.

Short-chain chlorinated paraffin (SCCP) exposure and type 2 diabetes risk: A population-based case-control study in East China

Exposure to persistent organic pollutants may be associated to type 2 diabetes, but the studies on associations between short-chain chlorinated paraffin (SCCP) exposure and type 2 diabetes risk in humans are still scarce. Here, we conducted a case-control study involving 344 participants in Shandong Province, East China, to explore the effects of SCCPs on type 2 diabetes risk and their correlations with glycemic biomarker and serum lipid parameters. SCCPs were detected in all serum samples with a median concentration of 24 ng mL-1 in cases and 19 ng mL-1 in controls. Exposure to C10-CPs, C11-CPs, and ΣSCCPs were positively associated with the risk of type 2 diabetes after adjusting for confounders. The associations remained consistent in stratified analyses but stronger in male participants and obese individuals. In the control group, there were significant and positive correlations between SCCP exposure and levels of total cholesterol (TC), low-density lipoprotein-cholesterol (LDL-C), total lipid, and non-high-density lipoprotein-cholesterol. Significant joint effects on SCCP exposure and lipid parameters were observed in females when analyzed by the quantile-based g-computation model, and C10-CPs showed the highest contribution. Mediation analysis showed that LDL-C had significant mediation effects on the associations between C10-CPs, C11-CPs, and ΣSCCPs exposure and risk of type 2 diabetes. Moreover, TC and high-density lipoprotein-cholesterol were mediators in the relationship between C11-CPs and type 2 diabetes. Taken together, our study revealed that human exposure to SCCPs may increase the risk of type 2 diabetes and disrupt lipid metabolism.

Biomonitoring, exposure routes and risk assessment of chlorinated paraffins in humans: a mini-review

Chlorinated paraffins (CPs), which were conventionally classified into short- (SCCPs), medium- (MCCPs) and long- (LCCPs) chain CPs, have received growing attention due to their wide usage and extensive detection in environmental samples and biota. The number of studies regarding the biomonitoring of CPs in human beings increased rapidly and their health risk gained great concern. This review summarized their occurrence and homologue patterns in human matrices including blood/serum, placenta, cord serum and breast milk. As the production and usage of SCCPs was progressively banned after being listed in Annex A of the Stockholm Convention, the production of MCCPs and LCCPs was stimulated. Accordingly, the ratio of MCCPs/SCCPs in human samples has increased rapidly in the last 5 years. The current understanding of exposure routes and risk assessments of CPs was also reviewed. Oral dietary intake is the most predominant source of daily CP intake, but dust ingestion, inhalation and dermal exposure is also nonnegligible, especially for MCCPs and LCCPs. Furthermore, the reported upper bound of the estimated daily intakes (EDIs) in various risk assessment studies was close to or exceeded the tolerable daily intakes (TDIs). Considering the bioaccumulation and long-lasting exposure of CPs, their health impacts on humans and the ecosystem required continuous monitoring and evaluation.

Chlorinated Paraffin Pollution in the Marine Environment

Chlorinated paraffins (CPs) are ubiquitous in the environment due to their large-scale usage, persistence, and long-range atmospheric transport. The oceans are a critical environment where CPs transformation occurs. However, the broad impacts of CPs on the marine environment remain unclear. This review describes the sources, occurrence and transport pathways, environmental processes, and ecological effects of CPs in the marine environment. CPs are distributed in the global marine environment by riverine input, ocean currents, and long-range atmospheric transport from industrial areas. Environmental processes, such as the deposition of particle-bound compounds, leaching of plastics, and microbial degradation of CPs, are the critical drivers for regulating CPs' fate in water columns or sediment. Bioaccumulation and trophic transfer of CPs in marine food webs may threaten marine ecosystem functions. To elucidate the biogeochemical processes and environmental impacts of CPs in marine environments, future work should clarify the burden and transformation process of CPs and reveal their ecological effects. The results would help readers clarify the current research status and future research directions of CPs in the marine environment and provide the scientific basis and theoretical foundations for the government to assess marine ecological risks of CPs and to make policies for pollution prevention and control.

Toxic effects and toxicological mechanisms of chlorinated paraffins: A review for insight into species sensitivity and toxicity difference

Chlorinated paraffins (CPs), a group of chlorinated alkane mixtures, are frequently detected in various environmental matrices and human bodies. Recently, CPs have garnered considerable attention owing to their potential to induce health hazards in wildlife and human. Several reviews have discussed short-chain CPs (SCCPs) induced ecological risk; however, a comprehensive understanding of the underlying toxic mechanisms and a comparison among SCCPs, medium-, and long-chain CPs (MCCPs and LCCPs, respectively) are yet to be established. This review summarizes the latest research progress on the toxic effects and the underlying molecular mechanisms of CPs. The main toxicity mechanisms of CPs include activation of several receptors, oxidative stress, disturbance of energy metabolism, and inhibition of gap junction-mediated communication. The sensitivity of different species to CP-mediated toxicities varies markedly, with aquatic organisms exhibiting the highest sensitivity to CP-induced toxicity. The toxicity comparison analysis indicated that MCCPs may be unsafe as potential substitutes for SCCPs.

Source toxicity characteristics of short- and medium-chain chlorinated paraffin in multi-environmental media: Product source toxicity, molecular source toxicity and food chain migration control through silica methods

Short and medium-chain chlorinated paraffin (SCCP/MCCP) have been widely studied because of their extensive environmental hazards. In this study, product source toxicity, molecular source toxicity and food chain migration of SCCP and MCCP in multi-environmental media were comprehensively considered. The additive combination of SCCP and MCCP in the air, water and soil environment was adjusted, and PVC, PU and rubber products with the lowest source toxicity were screened. The source toxicity of SCCP and MCCP in the water environment was inhibited by design of the feed additive addition scheme (highest inhibition was 16.29 %), and the source toxicity of SCCP and MCCP in the soil environment was affected by different field management measures (highest inhibition was 38.22 %). A forage fertilizer addition plan, a cattle feed addition plan and a special population healthy complementary food regulation plan were developed to prevent the migration step by step and absorption of SCCP and MCCP in the terrestrial food chain. In addition, by means of density functional theory and analysis of key amino acid residues, the mechanism of toxicity difference between SCCP and MCCP was analyzed from the level of chemical interaction, and rationality of the inhibition scheme designed in this study was verified.

Concentrations and homologue patterns of SCCPs and MCCPs in the serum of the general population of adults in Hangzhou, China

Due to their ubiquitous presence in the environment and humans, chlorinated paraffins (CPs) are a major environmental and public health concern. CPs are known to persist, bioaccumulate and potentially threaten human health, but reports on their internal exposure in the adult general population are still scarce. In this study, serum samples collected from adults living in Hangzhou, China, were quantified for SCCPs and MCCPs using GC-NCI-MS methods. A total of 150 samples were collected and subjected to analysis. ∑SCCPs were detected in 98% of the samples with a median concentration of 721 ng/g lw. MCCPs were found in all serum samples with a median concentration of 2210 ng/g lw, indicating that MCCPs were the dominant homologous group. For SCCPs and MCCPs, ∑C₁₀ and ∑C₁₄ were found to be the dominant carbon chain length homologues. Our results showed that age, BMI and lifestyle were not found to be significantly associated with internal exposure to CPs for the samples in this study. Based on PCA analysis, an age-specific distribution of CP homologues was observed. This suggests that internal exposure to CPs in the general population is related to exposure scenarios and history. The results of this study may contribute to a better understanding of the internal exposure to CPs in the general population and may provide a direction for the investigation of the source of exposure to CPs in the environment and daily life.

Synthesis, identification, chiral separation and crystal structure of (3R,4R,7S,8S)-3,4,7,8-tetrachlorodecane and its stereoisomers

Chlorinated paraffins (CPs) are a notoriously known class of compounds that stand amongst the most wide-spread persistent organic pollutants. Therefore, their reliable, repeatable, and reproducible quantitative analysis using well-defined reference standards is of utmost importance. In view of the increasing demand for constitutionally and stereochemically defined CP standards, we have synthesized a stereoisomeric mixture of 3,4,7,8-tetrachlorodecane. One stereoisomer - (3R,4R,7S,8S)-3,4,7,8-tetrachlorodecane was separated from the mixture, and enriched fractions of residual stereoisomers were achieved through crystallisation of the residual mother liquors. The molecular structure of the single isolated stereoisomer was confirmed through single-crystal X-ray crystallographic data. One fraction of 3,4,7,8-tetrachlorodecane stereoisomers was successfully separated on a chiral stationary phase using supercritical fluid chromatography hyphenated to mass spectrometry (column: Chiral ART Amylose-C; mobile phase: CO₂/MeOH (96/4 v/v) with 0.1% diethylamine). The reported separation of stereoisomers is unprecedented in CP analysis so far.

The potential health risks of short-chain chlorinated paraffin: A mini-review from a toxicological perspective

Short-chain chlorinated paraffins (SCCPs) are ubiquitously distributed in various environmental matrics due to their wide production and consumption globally in the past and ongoing production and use in some developing countries. SCCPs have been detected in various human samples including serum, milk, placenta, nail, and hair, and internal SCCP levels were found to be positively correlated with biomarkers of some diseases. While the environmental occurrence has been reported in a lot of studies, the toxicity and underlying molecular mechanisms of SCCPs remain largely unknown. The current tolerable daily intakes (TDIs) recommended by the world health organization/international programme on chemical safety (WHO/IPCS, 100 μg/kg bw/d) and the UK Committee on Toxicity (COT, 30 μg/kg bw/d) were obtained based on a no observed adverse effect level (NOAEL) of SCCP from the repeated-dose study (90 d exposure) in rodents performed nearly 40 years ago. Importantly, the health risks assessment of SCCPs in a variety of studies has shown that the estimated daily intakes (EDIs) may approach and even over the established TDI by UK COT. Furthermore, recent studies revealed that lower doses of SCCPs could also result in damage to multiple organs including the liver, kidney, and thyroid. Long-term effects of SCCPs at environmental-related doses are warranted.

Assessment of silicone wristbands for monitoring personal exposure to chlorinated paraffins (C8-36): A pilot study

Chlorinated paraffins (CPs) are a major environmental concern due to their ubiquitous presence in the environment. Since human exposure to CPs can significantly differ among individuals, it is essential to have an effective tool for monitoring personal exposure to CPs. In this pilot study, silicone wristbands (SWBs) were employed as a personal passive sampler to measure time-weighted average exposure to CPs. Twelve participants were asked to wear a pre-cleaned wristband for a week during the summer of 2022, and three field samplers (FSs) in different micro-environments were also deployed. The samples were then analyzed for CP homologs by LC-Q-TOFMS. In worn SWBs, the median concentrations of quantifiable CP classes were 19 ng/g wb, 110 ng/g wb, and 13 ng/g wb for ∑SCCPs, ∑MCCPs, and ∑LCCPs (C_18-20), respectively. For the first time, lipid content is reported in worn SWBs, which could be a potential impact factor in the kinetics of the accumulation process for CPs. Results showed that micro-environments were key contributors to dermal exposure to CPs, while a few outliers suggested other sources of exposure. CP exposure via dermal contact showed an increased contribution and thus poses a nonnegligible potential risk to humans in daily life. Results presented here provide proof of concept of the use of SWBs as a cheap and non-invasive personal sampler in exposure studies.

Declining concentrations of chlorinated paraffins in endangered St. Lawrence Estuary belugas (Delphinapterus leucas): Response to regulations or a change in diet?

Very high levels of industrial contaminants in St. Lawrence Estuary (SLE) beluga whales represent one of the major threats to this population classified as endangered under the Species at Risk Act in Canada. Elevated concentrations of short-chained chlorinated paraffins (SCCPs) were recently reported in blubber of adult male SLE belugas. Recent regulations for SCCPs in North America, combined with their replacement by medium- (MCCPs) and long-chained chlorinated paraffins (LCCPs), highlight the importance of tracking this toxic chemical class. The objectives of this study were to evaluate (1) levels and profiles of chlorinated paraffins (CPs) in samples obtained from carcasses of adult male, adult female, juvenile, newborn, and fetus beluga, and (2) trends in adult male belugas between 1997 and 2018. Factors potentially influencing CP temporal trends such as age, feeding ecology and sampling year were also explored. SCCPs dominated (64 to 100%) total CP concentrations across all age and sex classes, MCCPs accounted for the remaining proportion of total CPs, and LCCPs were not detected in any sample. The chlorinated paraffin homolog that dominated the most in beluga blubber was C₁₂Cl₈. Adult male SCCP concentrations from this study were considerably lower (> 2000-fold) than those recently reported in Simond et al. (2020), likely reflecting a previously erroneous overestimate due to the lack of a suitable analytical method for SCCPs at the time. Both SCCPs and total CPs declined over time in adult males in our study (rate of 1.67 and 1.33% per year, respectively), presumably due in part to the implementation of regulations in 2012. However, there is a need to better understand the possible contribution of a changing diet to contaminant exposure, as stable isotopic ratios of carbon also changed over time.

Short and medium-chain chlorinated paraffins in indoor dust from a multistory residential building in Beijing, China: Vertical distribution and potential health risks

In this study, we conducted a preliminary investigation of the vertical distribution and potential health risks of short and medium-chain chlorinated paraffins (SCCPs and MCCPs) in indoor dust from a multistory residential building in Beijing, China. Forty-eight SCCP and MCCP congener groups in dust from different floors of the multistory residential building were determined by two-dimensional gas chromatography coupled with electron capture negative ionization mass spectrometry. The concentration ranges for SCCPs and MCCPs in the dust samples were 0.0239-207 μg/g and 0.135-2903 μg/g, respectively. MCCPs were the dominant group, on average accounting for 76.8 % of ∑CPs. Generally, the concentrations of both SCCPs and MCCPs greatly decreased as the floor level increased, which indicated that the CP contamination was attributed to exogenous atmospheric transport and deposition. C₁₃Cl_7-8 and C₁₄Cl_7-8 were the dominant SCCP and MCCP congener groups, possibly indicating the use of industrial CP-52 products was the main source of CPs. In the worst-case scenario using the maximum concentrations of CPs, the daily intake of SCCPs for toddlers was of the same order of magnitude as the reference dose. It should be noted that CPs exposure may be more serious when indoor decorations, furniture, and various plastic products are taken into consideration. Overall, more attention should be paid to CPs exposure and control measures in high-rise buildings.

Comparative in vitro metabolism of short chain chlorinated paraffins (SCCPs) by human and chicken liver microsomes: First insight into heptachlorodecanes

Short chain chlorinated paraffins (SCCPs) are emerging persistent organic pollutants of great concern due to their ubiquitous distribution in the environment. However, little information is available on the biotransformation of SCCPs in organisms. In this study, a chlorinated decane: 1, 2, 5, 5, 6, 9, 10-heptachlorodecanes (HeptaCDs) was subjected to in vitro metabolism by human and chicken liver microsomes at environmentally relevant concentration. Using ultra-performance liquid chromatography-Q-Exactive Orbitrap mass spectrometry, two metabolites: monohydroxylated hexachlorodecane (HO-HexCD) and monohydroxy heptachlorodecane (HO-HeptaCD) were detected in human liver microsomal assays, while only one metabolite (HO-HexCD) was identified in chicken liver microsomal assays. The formation of HO-HexCD was fitted to a Michaelis-Menten model for chicken liver microsomes with a V_max (maximum metabolic rate) value of 4.52 pmol/mg/min. Metabolic kinetic parameters could not be obtained for human liver microsomes as steady state conditions were not reached under our experimental conditions. Notwithstanding this, the observed average biotransformation rate of HeptaCDs was much faster for human liver microsomes than for chicken liver microsomes. Due to the lack of authentic standards for the identified metabolites, the detailed structure of each metabolite could not be confirmed due to the possibility of conformational isomers. This study provides first insights into the biotransformation of SCCPs, providing potential biomarkers and enhancing understanding of bioaccumulation studies.

Land-Ocean Exchange Mechanism of Chlorinated Paraffins and Polycyclic Aromatic Hydrocarbons with Diverse Sources in a Coastal Zone Boundary Area, North China: The Role of Regional Atmospheric Transmission

The marine environment is regarded as a crucial "sink" of numerous land-origin pollutants. As typical boundary regions, the coastal and offshore areas are used to evaluate the dominating transfer process and land-ocean exchange mechanism of semivolatile organic compounds. In air samples collected from a coastal area in North China over a whole year, chlorinated paraffins (CPs), including short-chain CPs and medium-chain CPs, and prior control 16 polycyclic aromatic hydrocarbons (PAHs) were determined, with mean concentrations of 25.8 and 94.7 ng/m³, respectively. Results of different gas-particle partitioning models indicated that the steady-state hypothesis provides a better description of the possible land-ocean exchange molecular mechanism. The source-sink influences for CPs and PAHs were affected by the predominant atmospheric motion, which alternated between gaseous diffusion and particulate sedimentation in different seasons. Source apportionment results indicated that different transfer characteristics contributed to the source divergence of ambient CPs and PAHs within 12 nautical miles in the same area. Coal/biomass combustion and diesel/natural gas combustion were the main PAH sources in the coast site (43.1%) and sea site (35.3%), respectively. Similar industrial sources CP-52 and CP-42 were the main CP sources in the coast site (41.4%) and sea site (40.8%), respectively.

Assessing Safety of Market-Sold Fresh Fish: Tracking Fish Origins and Toxic Chemical Origins

Increasing global and domestic food trade and required logistics create uncertainties in food safety inspection due to uncertainties in food origins and extensive trade activities. Modern blockchain techniques have been developed to inform consumers of food origins but do not provide food safety information in many cases. A novel food safety tracking and modeling framework for quantifying toxic chemical levels in the food and the food origins was developed. By integrating chemicals' multimedia environment exchange, food web, and source tracking systems, the framework was implemented to identify short-chain chlorinated paraffin (SCCP) contamination of fresh hairtail fish sold by a Walmart supermarket in Xi'an, northwestern China, and sourced in Eastern China Sea coastal waters. The framework was shown to successfully predict SCCP level with a mean of 17.8 ng g^-1 in Walmart-sold hairtails, which was comparable to lab-analyzed 21.9 ng g^-1 in Walmart-sold hairtails. The framework provides an alternative and cost-effective approach for safe food inspection compared to traditional food safety inspection techniques. These encouraging results suggest that the approach and rationale reported here could add additional information to the food origin tracking system to enhance transparency and consumers' confidence in the traded food they consumed.

Monitoring temporal trends of dioxins, organochlorine pesticides and chlorinated paraffins in pooled serum samples collected from Northern Norwegian women: The MISA cohort study

The ubiquitous presence of legacy and emerging persistent organic pollutants (POPs) in the environmental matrices poses a potential hazard to the humans and creating public health concerns. The present study aimed to evaluate dioxins, dioxin-like polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and chlorinated paraffins (CPs) concentrations in serum of women (postpartum, pregnant and non-pregnant) from Northern Norway to better understand their exposure and contamination status as well as temporal trends across 2007-2009 (MISA 1) to 2019 (MISA 2). Sixty-two blood samples from the MISA 1 cohort and 38 samples from MISA 2 were randomly selected in this study (n = 100). Ninety samples from postpartum (MISA 1) and pregnant women (MISA 2) were randomly combined into 9 pools, with 9-11 individual samples contributing to each pool keeping the groups of pregnant and postpartum women. Remaining 10 samples from non-pregnant women (MISA 2) were allocated into separate group. Geometric mean, minimum and maximum were used to describe the serum concentrations of pooled POPs in MISA cohort. Mann-Whitney U test and independent sample t-test were applied for trend analysis of blood levels of POPs between MISA 1 and MISA 2. We found the serum concentrations of selected POPs in this study to be at lower range. Serum concentrations of dibenzo-p-dioxins (PCDDs) (p = 0.010), polychlorinated dibenzofurans (PCDFs) (p = 0.002), dioxins-like PCBs (p = 0.001), hexachlorobenzene (HCB) (p < 0.001) and p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) (p = 0.002) were decreased between the studied time. In contrast, the serum concentrations of medium chain chlorinated paraffins showed an increasing trend between 2007 and 2009 and 2019 (p = 0.019). Our findings report a particular concern of emerging contaminant medium chain chlorinated paraffin exposure to humans. Future observational studies with repeated measurements of chlorinated paraffins in general populations worldwide and large sample size are warranted.

Integrated assessment of endocrine disrupting potential of four novel brominated flame retardants

Novel brominated flame retardants (NBFRs) have emerged as alternatives to the legacy BFRs due to BFRs' persistence, bioaccumulation and evidence of adverse health effects. The increasing production of NBFRs has led to the frequent detection in environmental media and even in organisms. Thus the potential health risks of these novel NBFRs need to be taken into account. Herein, the endocrine disrupting effects of the four NBFRs (α/β-TBCO, PBEB, EHTBB and BEHTBP) were evaluated by constructing an estrogen receptor (ERα), glucocorticoid receptor (GR), and mineralocorticoid receptor (MR) mediated dual-luciferase reporter gene assays on the CHO cells, in combination with steroid experiments on the H295R cells and molecular docking. The results revealed that α/β-TBCO, PBEB and EHTBB induced anti-estrogenic activity at certain concentrations while none of the four NBFRs was agonistic to ERα. For reporter gene assay, only PBEB exhibited GR antagonistic effects. Notably, none of the four NBFRs possess neither agonistic nor antagonistic activity of MR. The molecular docking results were generally consistent with the reporter gene assay, which showed the different binding affinities between NBFRs and the receptors. For steroidogenesis, α/β-TBCO, PBEB, and EHTBB all upregulated genes encoding for steroid synthesis enzymes, including 17βHSD, CYP11B1 and CYP17. Altogether, the data clarified that NBFRs may pose risks of endocrine disruption.

New insights into potential estrogen agonistic activity of triazole fungicides and coupled metabolic disturbance

Triazole fungicides are highly effective pesticides widely used in plant protection, which has caused potential hazards to human health and ecological safety. To fully understand their potential hepatotoxicity, we first analyzed the transcriptome profiles in HepG2 cells treated with five triazole fungicides (hexiconazole (HEX), tebuconazole (TEB), propiconazole (PRO), cyproconazole (CYP), and difenoconazole (DIF)), and found that these pesticides remarkably affected estrogen signaling pathways, especially estrogen synthesis. Furthermore, we found that TEB, CYP, PRO and DIF had agonistic activity towards estrogen receptor alpha (ERα) and elucidated the binding mode of triazole ligands with ERα using the reporter gene assay and molecular docking. Four triazole fungicides regulated eight major genes involved in estrogen synthesis (StAR, CYP11A1, 3βHSD2, CYP17, CYP19, CYP3A4, CYP1A2 and SCP2) and stimulated the secretion of 17β-estradiol (E₂). Finally, we assessed possible metabolic outcomes caused by abnormal estrogen synthesis, and found that triazole fungicides affected the metabolism of various macromolecules (such as lipid, amino acid, and carbohydrate) and signal transduction. These findings will provide new insights into endocrine-disrupting effects of triazole fungicides and highlight their potential ecological and health risks.

Profile occurrences and in vitro effects of toxic organic pollutants in metal shredding facilities in Wallonia (Belgium)

End-of-life vehicles and e-waste contain several hazardous substances that can contaminate the environment during treatment processes. Occurrences and adverse effects of toxic organic pollutants emitted from 3 shredder plants located in Wallonia, Belgium, were investigated by chemical and biological analyses of fluff, dust, and scrubbing sludge sampled in 2019. Site 1 showed the highest concentrations of chlorinated compounds in sludge with 7.5 ng/g polychlorinated dibenzo-dioxins/furans and 84.5 µg/g estimated total polychlorinated biphenyls, while site 3 led the brominated flame retardant levels in dust (53.4 µg/g). The level of polycyclic aromatic hydrocarbons was highest in the sludge samples, 78 and 71 µg/g for sites 2 and 3, respectively. The samples induced significant dioxin-like activities in murine and human cells at concentrations of around 0.01-0.1 and 0.5-1 ng (sample) per ml (medium), respectively, with the efficacy similar to 2,3,7,8-tetrachlorodibenzodioxin and EC₅₀ values of around 1 and 10 ng/ml. The samples also displayed high estrogenic activities, already at 1 ng/ml, and several induced a response as efficient as 17β-estradiol, albeit a low androgenic activity. Shredder workers were estimated to be highly exposed to dioxin-like compounds through dust ingestion and dermal absorption, which is of concern.

Toxicological Effect and Molecular Mechanism of the Chiral Neonicotinoid Dinotefuran in Honeybees

With the increasing demand for pollinating services, the wellness of honeybees has received widespread attention. Recent evidence indicated honeybee health might be posed a potential threat by widely used neonicotinoids worldwide. However, little is known about the molecular mechanism of these insecticides in honeybees especially at an enantiomeric level. In this study, we selected two species of bees, Apis mellifera (A. mellifera) and Apis cerana (A. cerana), to assess the toxicity and molecular mechanism of neonicotinoid dinotefuran and its enantiomers. The results showed that S-dinotefuran was more toxic than rac-dinotefuran and R-dinotefuran to honeybees by oral and contact exposures as much as 114 times. A. cerana was more susceptible to highly toxic enantiomer S-dinotefuran. S-dinotefuran induced the immune system response in A. cerana after 48 h exposure and significant changes were observed in the neuronal signaling of A. mellifera under three forms of dinotefuran exposure. Moreover, molecular docking also revealed that S-dinotefuran formed more hydrogen bonds than R-dinotefuran with nicotinic acetylcholine receptor, indicating the higher toxicity of S-dinotefuran. Data provided here show that R-dinotefuran may be a safer alternative to control pests and protect pollinators than rac-dinotefuran.

Concentrations and distribution of chlorinated paraffins in Belgian foods

This study reports on concentrations of short- and medium-chain chlorinated paraffins (SCCPs and MCCPs, respectively) in a wide range of food samples (n = 211) purchased in Belgium during 2020. Samples were analysed by gas chromatography-mass spectrometry (GC-MS) and quantified using chlorine content calibration. ∑SCCPs were present above LOQ in 25% of samples with an overall range of <LOQ to 58 ng/g wet weight (ww), while ∑MCCPs were identified in 66% of samples ranging from <LOQ to 250 ng/g ww. ∑MCCP concentrations were greater than those of ∑SCCPs in all 48 samples in which both groups were detected with an average ∑MCCP/∑SCCP ratio of 5.8 (ranging from 1.3 to 81). In general, the greatest CP concentrations were observed in foods classified as animal and vegetable fats and oils and sugar and confectionary for both SCCPs and MCCPs. Significant correlations between lipid content in food samples and CP levels illustrated the role of lipids in accumulating CPs within foodstuffs, while industrial processing, food packaging and environmental conditions are each likely to contribute to overall CP loads. Selected samples (n = 20) were further analysed by liquid chromatography-high resolution MS (LC-HRMS) to investigate homologue profiles and the occurrence of long-chain CPs (LCCPs). LCCPs were detected in 35% of the 20 subset samples while the HRMS results for SCCPs and MCCPs matched closely with those obtained by GC-MS. This study reveals the widespread occurrence of SCCPs and MCCPs in Belgian food and indicates that LCCPs may represent a substantial contribution to overall CP levels in foodstuffs.

Bioaccumulation and trophic magnification of short chain chlorinated paraffins in marine organisms from East China Sea

As new persistent organic pollutants, short chain chlorinated paraffins (SCCPs) have recently received particular attention. However, knowledge on their bioaccumulation and trophic magnification in marine organisms from East China Sea (ECS) is still scare. In this study, we investigated the concentrations of SCCPs in seawater (n = 15) and marine organisms (n = 88) collected from ECS. The total concentrations of SCCPs (∑SCCPs) ranged from 12.5 to 242 ng/L in seawater and from 12.8 to 1819 ng/g wet weight (ww) in organisms. C_10-11 SCCPs and Cl_5-7 SCCPs were the predominant homologues in all samples, with the mean proportions of 70 ± 6.5% and 80 ± 7.8% in seawater, as well as 52-77% and 61-84% in marine organisms, respectively. The logarithm bioaccumulation factor (log BAF) values of ∑SCCPs were in the range of 2.04-3.79 in zooplankton, fish, shrimp, crab, shellfish, snail, and cephalopod. The log BAF values of SCCP homologues (1.33-4.75) increased significantly with the increase of their logarithm octanol-water partition coefficients (log K_OW) values, indicating that hydrophobicity is the major factor controlling the bioaccumulation of SCCPs. The trophic magnification factor (TMF) value of ∑SCCPs was calculated to be 3.98, indicating the potential trophic magnification of SCCPs in this marine food web from ECS. A slightly increasing trend was observed between the TMF values of SCCP homologues and their log K_OW values. Overall, for the first time, this study systematically examined the bioaccumulation and trophic magnification of SCCPs in the marine food web from East China Sea.

Evaluation of the immunomodulatory effects of C9-13-CPs in macrophages

Short-chain chlorinated paraffins (SCCPs) have been listed as a new class of persistent organic pollutants by the Stockholm Convention. SCCPs exhibit carcinogenic-, endocrine-, and metabolism-disrupting effects. However, the knowledge of the immunomodulatory effects of SCCPs and their underlying mechanisms, especially in specific immune cells, remains limited. In addition to SCCPs, C9-13-CPs have also been detected in humans. In this study, murine RAW264.7 macrophages were exposed to C9-13-CPs at environmentally relevant concentrations to investigate whether or how C9-13-CPs exhibit immunomodulatory effects. The results showed that the exposure of RAW264.7 cells to C9-13-CPs increased cell viability, as assayed by MTT analysis at 490 nm, and also promoted cell proliferation, as indicated by EdU uptake assay, which was measured at excitation and emission wavelengths of 488 and 512 nm, respectively. In addition, exposure to C9-13-CPs not only led to elevated ATP level and intracellular Ca2+ level but also caused AMPK signaling activation and NF-κB signaling inhibition. Moreover, molecular docking showed that the β2-AR receptor could bind to C9-13-CPs. Taken together, these results suggest that the immune dysfunction of RAW264.7 cells caused by C9-13-CPs is closely related to the β2-AR/AMPK/NF-κB signaling axis.

Percutaneous penetration and dermal exposure risk assessment of chlorinated paraffins

The widespread occurrence of chlorinated paraffins (CPs) in environmental matrices has resulted in a high frequency exposure to CPs via dermal contact. To quantitatively estimate percutaneous penetration of CPs, Episkin® human skin equivalents (HSE) was applied as an in vitro model to evaluate the mechanism of percutaneous penetration of CPs. The co-exposure of CPs mixtures to HSE showed that about 11.7% and 10.2% of short-chain CPs (SCCPs) and medium-chain CPs (MCCPs) could penetrate the HSE and enter the receptor fluid, while no long-chain CPs (LCCPs) (C>17) were able to penetrate the HSE during the 36-h assay period. The experimentally obtained permeability coefficient (K_p) values for CPs were significantly (p < 0.01) negatively correlated with their log octanol-water partition coefficient (log K_ow). Furthermore, 24 participants were recruited to assess direct human dermal exposure to CPs in China with the total CPs collected onto hand wipes and forehead wipes being 96,600 and 30,400 ng/person, respectively. The proportion of total SCCPs and MCCPs intake via dermal penetration (skin area investigated in this study) accounting for 2.0% of the total intake of CPs. Considering the total skin surface of human body is around 20 times of the area studied, the total intake of CPs through dermal penetration could be a significant exposure pathway.

Male renal functions are associated with serum short- and medium-chain chlorinated paraffins in residents from Jinan, China

BACKGROUND

Chlorinated paraffins (CPs) are contaminants ubiquitously detected in environmental samples, and reports addressing CPs in human samples are expanding. While CP exposure was suggested to impair kidney function by in vivo/in vitro experiments, epidemiological evidence is lacking.

OBJECTIVE

To examine the associations between serum total short-chain CP and medium-chain CP concentrations (∑SCCPs and ∑MCCPs) with human kidney function.

METHODS

The study samples were obtained from 387 participants living in Jinan, North China. We quantified ∑SCCPs and ∑MCCPs in serum samples and evaluated the kidney function of included subjects by estimated glomerular filtration rate (eGFR). The associations between serum ∑SCCPs, ∑MCCPs and eGFR were estimated using multivariable linear regression and logistic regression. The possible gender-dependent effects were studied by stratified analysis.

RESULTS

After adjusting for age, education, smoking status, drinking status, body mass index (BMI), family history of chronic kidney disease (CKD), fasting serum glucose, systolic blood pressure and diastolic blood pressure, higher concentrations of serum ∑SCCPs and ∑MCCPs were associated with higher male eGFR (β = 3.13 mL/min/1.73 m² per one ln-unit increase of serum ∑SCCPs, 95%CI: 1.72, 4.54, p = 0.016; β = 3.52 mL/min/1.73 m² per one ln-unit increase of serum ∑MCCPs, 95%CI: 1.89, 5.17, p = 0.011). Associations between serum ∑SCCPs, ∑MCCPs and female eGFR were null. Comparing higher (above the median serum CP levels) vs. lower exposure groups, serum ∑SCCPs and ∑MCCPs were associated with an elevated risk of glomerular hyperfiltration (GH, eGFR ≥ 135 mL/min/1.73 m²), which was associated with glomerular damage and represented as an early stage of chronic kidney disease (OR = 2.98; 95% CI: 1.24, 4.71 for SCCPs; OR = 3.25; 95% CI: 1.20, 5.29 for MCCPs).

CONCLUSIONS

Our study suggests that male serum ∑SCCPs and ∑MCCPs are associated with an increased risk of GH, indicating early-stage kidney impairment.

Stereoisomeric selectivity in the endocrine-disrupting potential of cypermethrin using in vitro, in vivo, and in silico assays

Despite the ubiquity of cypermethrin (CYP) stereoisomers in environment biota, the stereoisomeric selectivity of endocrine-disrupting potency of α-CYP, β-CYP, and θ-CYP has not been well studied. In this study, dual-luciferase reporter gene assays were adopted to analyze their potential endocrine-disrupting effects via four receptors (ERα, GRα, MR and RXR). The results showed that α-CYP was antagonistic to ERα, GRα, and MR with RIC₂₀ of 9.1 × 10^-7, 7.6 × 10^-7, and 1.0 × 10^-6 M, respectively. β-CYP exhibited only ERα-mediated agonistic activity with a REC₂₀ of 2.1 × 10^-6 M. None of the CYP stereoisomers interacted with RXR. Molecular docking indicated that α-CYP had the strongest binding capacity to GRα among the compounds. The expression levels of steroid hormone-related genes in human adrenocortical carcinoma (H295R) cells displayed that all three compounds inhibited the transcription of 3-βHSD, indicating the block of turning cholesterol into different hormones. Both α-CYP and β-CYP upregulated genes encoding estrogen- and aldosterone-forming enzymes including 17-βHSD, CYP19, STAR, and CYP11B2. Mortality and malformation toxicity assays in zebrafish embryos revealed that the order of toxicity was α-CYP > β-CYP > θ-CYP. Our results indicated that α-CYP may pose the strongest endocrine-disrupting effects. The data provided here will be helpful to systematically understand stereoisomeric selectivity in the endocrine-disrupting effects of cypermethrin.

Effect of short-chain chlorinated paraffins (SCCPs) on lipid membranes: Combination of molecular dynamics and membrane damage experiments

In recent years, more attention has been paid to the biological effects of short-chain chlorinated paraffin (SCCP). Studies have shown that SCCPs exposure could cause metabolic damage and lipid metabolic damage. In the present work, based on E. coli membrane damage experiments and molecular dynamics (MD) simulation, the effects of SCCPs on the membrane structure and membrane properties were studied to explore the possible toxic damage effects of SCCPs on cell membrane. Experiments results showed that SCCPs had a significant inhibitory effect on E. coli. The E. coli cell membrane of the bacteria was broken and the macromolecules of the cell flowed out when exposed to SCCPs. SCCPs would lead to the decrease and depolarization of cell membrane potential, and then affect the integrity and permeability of cell membrane. The further molecular dynamic simulation revealed that SCCP molecules can easily enter the lipid DPPC membranes from the aqueous phase and tended to aggregate inside bilayer stably. The bound of SCCPs could lead to significant variations in DPPC bilayer with a less dense, more disorder and rougher layer, which thus made the damage of cell membrane. In a word, although the overall toxicity of SCCPs to cell was relatively weak, the damage to the cell membrane may be one of the mechanisms of its toxicity. MAIN FINDING OF THE WORK: The exposure of SCCPs could cause structural change of cell membrane in E. coli, which verified the damage to the cell membrane may be one of the mechanisms of its toxicity.

Cross-Model Comparison of Transcriptomic Dose-Response of Short-Chain Chlorinated Paraffins

Short-chain chlorinated paraffins (SCCPs) have attracted attention because of their toxicological potential in humans and wildlife at environmentally relevant doses. However, limited information is available regarding mechanistic differences across species in terms of the biological pathways that are impacted by SCCP exposure. Here, a concentration-dependent reduced human transcriptome (RHT) approach was conducted to evaluate 15 SCCPs in HepG2 cells and compared with our previous results using a reduced zebrafish transcriptome (RZT) approach in zebrafish embryos (ZFEs). Generally, SCCPs induced a broader suite of biological pathways in ZFEs than HepG2 cells, and all of the 15 SCCPs were more potent in HepG2 cells compared to ZFEs. Despite these general differences, the transcriptional potency of SCCPs in both model systems showed a significant linear relationship (p = 0.0017, r² = 0.57), and the average ratios of transcriptional potency for each SCCP in RZT to that in RHT were ∼100,000. C₁₀H₁₄Cl₈ was the most potent SCCP, while C₁₀H₁₇Cl₅ was the least potent in both ZFEs and HepG2 cells. An adverse outcome pathway network-based analysis demonstrated model-specific responses, such as xenobiotic metabolism that may be mediated by different nuclear receptor-mediated pathways between HepG2 cells (e.g., CAR and AhR activation) and ZFEs (e.g., PXR activation). Moreover, induced transcriptional changes in ZFEs associated with pathways and molecular initiating events (e.g., activation of nicotinic acetylcholine receptor) suggest that SCCPs may disrupt neural development processes. The cross-model comparison of concentration-dependent transcriptomics represents a promising approach to assess and prioritize SCCPs.

Exposure to short-chain chlorinated paraffins inhibited PPARα-mediated fatty acid oxidation and stimulated aerobic glycolysis in vitro in human cells

Short-chain chlorinated paraffins (SCCPs) could disrupt fatty acid metabolism in male rat liver through activating rat PPARα signaling. However, whether this mode of action can translate to humans remained largely unclear. In this study, based on luciferase assays, C_10-13-CPs (56.5% Cl) at concentrations greater than 1 μM (i.e., 362 μg/L) showed weak agonistic activity toward human PPARα (hPPARα) signaling. But in HepG2 cells, exposure to C_10-13-CPs (56.5% Cl) at the human internal exposure level (100 μg/L) down-regulated expressions of most of the tested hPPARα target genes, which encode for enzymes that oxidize fatty acids. In line with the gene expression data, metabolomics further confirmed that exposure to four SCCP standards with varying chlorine contents at 100 μg/L significantly suppressed oxidation of fatty acids in HepG2 cells, mainly evidenced by elevations in both total fatty acids and long-chain acylcarnitines. In addition, exposure to these SCCPs also caused a shift in carbohydrate metabolism from the tricarboxylic acid cycle (TCA cycle) to aerobic glycolysis. Overall, the results revealed that SCCPs could inhibit hPPARα-mediated fatty acid oxidation, and stimulated aerobic glycolysis in HepG2 cells.

Increased adverse effects during metabolic transformation of short-chain chlorinated paraffins by cytochrome P450: A theoretical insight into 1-chlorodecane

Short-chain chlorinated paraffins (SCCPs), frequently detected in human tissues or organs, can result in threat to human health by disturbing normal metabolism. However, their metabolism mechanisms and fates are largely unclear. Therefore, to better understand the impacts of SCCPs and their metabolites on the human health, the metabolic mechanism and kinetics of SCCPs by cytochrome P450 enzymes (CYPs) were explored using density functional theory employed 1-chlorodecane as a model SCCPs. The results show that 1-chlorodecane could be readily metabolized by CYPs, and the rate constant reaches up 42.3 s^-1 in human body. Dechlorination of 1-chlorodecane is unlikely to occur and hydroxylation is dominated via H-abstraction pathways, especially from the intermediate C atom of 1-chlorodecane. The toxicity assessments suggest that the two metabolites, 10-chloro-decan-5-ol and 1-chlorodecanol could exhibit higher bioaccumulation, carcinogenicity and more serious damage on cardiovascular system after the metabolism of 1-chlorodecane. To our knowledge, this is the first study from the viewpoint of theoretical analysis to explore the metabolism of typical SCCPs in human body. It may provide deep insight into the metabolic transformation mechanism of SCCPs and cause the concerns about the adverse effects of their metabolites in human body.

Screening of potential oestrogen receptor α agonists in pesticides via in silico, in vitro and in vivo methods

In modern agricultural management, the use of pesticides is indispensable. Due to their massive use worldwide, pesticides represent a latent risk to both humans and the environment. In the present study, 1056 frequently used pesticides were screened for oestrogen receptor (ER) agonistic activity by using in silico methods. We found that 72 and 47 pesticides potentially have ER agonistic activity by the machine learning methods random forest (RF) and deep neural network (DNN), respectively. Among endocrine-disrupting chemicals (EDCs), 14 have been reported as EDCs or ER agonists by previous studies. We selected 3 reported and 7 previously unreported pesticides from 76 potential ER agonists to further assess ERα agonistic activity. All 10 selected pesticides exhibited ERα agonistic activity in human cells or zebrafish. In the dual-luciferase reporter gene assays, six pesticides exhibited ERα agonistic activity. Additionally, nine pesticides could induce mRNA expression of the pS2 and NRF1 genes in MCF-7 cells, and seven pesticides could induce mRNA expression of the vtg1 and vtg2 genes in zebrafish. Importantly, the remaining 48 out of 76 potential ER agonists, none of which have previously been reported to have endocrine-disrupting effects or oestrogenic activity, should be of great concern. Our screening results can inform environmental protection goals and play an important role in environmental protection and early warnings to human health.

Short- and Medium-Chain Chlorinated Paraffins in Polyvinylchloride and Rubber Consumer Products and Toys Purchased on the Belgian Market

This study investigates the presence of Stockholm Convention listed short-chain chlorinated paraffins (SCCPs) and their replacement medium-chain chlorinated paraffins (MCCPs) counterparts in polyvinyl chloride and rubber consumer products and toys purchased on the Belgian market in 2019. SCCPs were detected in 27/28 samples at concentrations ranging from <LOQ-130,000 µg/g with a median level of 2.5 µg/g, while MCCPs were detected in only five samples ranging <LOQ-3500 µg/g. Levels of SCCPs in all but one of the samples were below the European Union's guideline limit of 0.15%, by weight, and concentrations of both SCCPs and MCCPs in the majority of products suggested unintentional incorporation to the polymeric materials. The homologue distribution of SCCPs was generally dissimilar to known commercial formulations and appeared to be indicative of contamination during manufacture or via recycling of previously treated goods. MCCP patterns, conversely, were broadly representative of those reported for industrial mixtures and may have been inadvertently incorporated via the application of mixed carbon-chain length CP formulations or recycled goods. This research suggests that overall SCCP presence has decreased in goods on the European market compared with previous reports and that both SCCPs and MCCPs may still enter EU marketplaces from unintentional sources.

Occurrence of Chlorinated Paraffins in a Wetland Ecosystem: Removal and Distribution in Plants and Sediments

Constructed wetlands (CWs) are of great socioeconomic significance because they can remove anthropogenic compounds from aquatic environments. However, no information is available about the removal of persistent chlorinated paraffins by CWs. This study investigates the occurrences, fates, and mass balances of short-chain chlorinated paraffins (SCCPs), medium-chain chlorinated paraffins (MCCPs), and long-chain chlorinated paraffins (LCCPs) in a CW ecosystem. MCCPs were the predominant compounds in water, sediments, and plants within the system. The amounts of SCCPs, MCCPs, and LCCPs entering the wetland were 3.3, 6.8, and 3.4 g/day, respectively. Overall removal efficiencies were 51-78%, 76-86%, and 76-91% for SCCPs, MCCPs, and LCCPs, respectively, and the greatest reduction in CPs was observed in the subsurface flow wetland unit. CPs were predominantly adsorbed onto the sediment and bioaccumulated in the plants, and their organic carbon-water partitioning and plant-water accumulation increased as the carbon and chlorine numbers increased. Sediment sorption (12-38%) and degradation (12-50%) contributed the most to the removal of CPs, but bioaccumulation of CPs in plants (3.8-12%) should not be neglected. Wetlands can economically remove large amounts of CPs, but sediment in the wetland systems could be a sink for CP pollutants.

Effect of short-chain chlorinated paraffins on metabolic profiling of male SD rats

The toxic effect of high-dose of short-chain chlorinated paraffins (SCCPs) has been extensively studied, however the possible health risks induced by SCCPs at low-dose remain largely unknown. In this study, a comprehensive toxicology analysis of SCCPs was conducted with the exposure levels from the environmental dose to the Lowest Observed Adverse Effect Level (LOAEL) of 100 mg/kg/day. General toxicology analysis revealed inconspicuous toxicity of the environmental dose of SCCPs, high dose SCCP exposure inhibited the growth rate and increased the liver weight of rat. Metabolomics analysis indicated that SCCP-induced toxicity was triggered at environmentally relevant doses. First, inhibition of energy metabolism was observed with the decrease in blood glucose and the dysfunction of TCA cycle, which may have contributed to lower body weight gain in rats exposed to a high dose of SCCPs. Second, the increase of free fatty acids indicated the acceleration of lipid metabolism to compensate for the energy deficiency caused by hypoglycemia. Lipid oxidative metabolism inevitably leads to oxidative stress and stimulates the up-regulation of antioxidant metabolites such as GSH and GSSH. The up-regulation of polyunsaturated fatty acids (PUFAs) and phospholipids composed of arachidonic acid indicates the occurrence of inflammation. Dysfunction of lipid metabolism can be an indicator of SCCP-induced liver injury.

Protein-affinity guided identification of chlorinated paraffin components as ubiquitous chemicals

Chlorinated paraffins (CPs) have been extensively examined to identify their components. Short-chain CPs with a carbon number of 10-13 have been strictly restricted or banned due to their addition to the list of Persistent Organic Pollutants in the world. However, more constituents with potential toxicities in these complicated mixtures are still unclear. In the present study, a purification method based on the protein affinity of thyroid hormone-related proteins (transthyretin and thyroid receptor) was established. The protein-based affinity extraction coupled with high-throughput scanning successfully discover a new group of chlorinated compounds (CP(O₂)) in commercial CP mixtures. The CP(O₂)s were purified from the commercial mixtures and identified to be chlorinated fatty acid methyl esters (CFAMEs) with a carbon chain length of 17-19 and 3-11 chlorines by a combination of liquid-liquid extraction, hydrolysis, Fourier transform infrared spectrometry and Orbitrap mass spectrometry. The newly identified CFAMEs were found to be ubiquitous in the environmental matrices, and concentration ratios of ∑CFAMEs/∑CPs ranged from 0.01 to 35 in air, soil and food samples. CFAMEs were also detected in blood samples of general populations, and accumulated in humans through dietary uptake. CFAMEs can compete with T4 for binding TTR with higher potencies than CPs, possibly leading to disruptions of thyroid hormone homeostasis.

A simplified screening method for short- and medium-chain chlorinated paraffins in food by gas chromatography-low resolution mass spectrometry

This study evaluates the performance of a simplified screening method for short- and medium-chain chlorinated paraffins (SCCPs and MCCPs, respectively) based on gas chromatography-electron capture negative ionization/mass spectrometry (GC-ECNI/MS) analysis and chlorine content quantification. The response from different combinations of 'indicator' congener groups present in technical mixture standards were used within calibration calculations to test the hypothesis that ∑SCCPs and ∑MCCPs could be quantified with acceptable accuracy using only a subset of the commonly analysed C₁₀ to C₁₇ and Cl₅ to Cl₁₀ groups. Potential combinations were assessed with respect to calibration curve performance and accuracy of SCCP and MCCP analysis of spiked food samples (olive oil, salmon, pork sausage, breakfast cereal, cow's milk and lard). Based on these trials, a screening method which quantifies ∑SCCPs and ∑MCCPs using only congener groups with 6 and 8 chlorine atoms for each carbon chain length was proposed. Concentrations of SCCPs and MCCPs in triplicate analyses of spiked food samples calculated using the proposed screening method deviated by ≤ 25% for the vast majority of samples (maximum deviation 37%) from levels determined using all analysed congener groups. The mean trueness of the screening method as applied to each of the spiked food samples and lard samples from a previous European Union Reference Laboratory (EURL) interlaboratory study ranged from 65 to 110% for ∑SCCPs and 102 to 175% for ∑MCCPs. Relative standard deviations (RSDs) were ≤ 25% for all triplicate analyses and matrix specific LOQs ranged from 0.7 to 6 ng/g ww for ∑SCCPs and from 1.3 to 12 ng/g ww for ∑MCCPs. The proposed screening method has the potential to deliver substantial time savings in instrumental analysis and manual labour without greatly reducing the overall accuracy and sensitivity of SCCP and MCCP quantification.

Occurrence, trophic magnification and potential risk of short-chain chlorinated paraffins in coral reef fish from the Nansha Islands, South China Sea

As emerging persistent organic pollutants in marine environment, short-chain chlorinated paraffins (SCCPs) have attracted increasing attentions recently. Coral reefs are important ocean ecosystems. However, data on SCCP pollution in the coral reef regions is still unavailable. In the present work, bioaccumulation of SCCPs in the coral reef ecosystems was reported for the first time. SCCP concentrations in coral reef fish from the Nansha Islands of the South China Sea were in the range of 37.9-25,400 ng/g lipid weight (lw) (average: 4400 ± 6590 ng/g lw; median: 1020 ng/g lw). C₁₀ SCCPs were the dominating SCCP homologues, accounting for 59% to 80% of the total SCCPs (average: 70 ± 5.0%), followed by C₁₁ SCCPs (average: 23 ± 4.5%). Regarding chlorine substitution, SCCPs were dominated by Cl₇ SCCPs (average: 45 ± 2.5%) and Cl₈ SCCPs (average: 30 ± 5.4%). Trophic magnification factor (TMF) of total SCCPs was 8.5, indicating trophic magnification potential of SCCPs in the coral reef ecosystems. In addition, a parabolic relationship was established between TMFs and log K_ow of specific SCCP homologues. SCCP residues in the coral reef fish from the Nansha Islands of the South China Sea did not pose significant risk to human health.

Risk assessment of the lipid metabolism-disrupting effects of nitro-PAHs

Nitro-polycyclic aromatic hydrocarbons (NPAHs) are of increasing global concern due to their ubiquitous occurrence and long-range transport in the environment. However, their potential metabolism-disrupting effects, especially nuclear receptor-related lipid disorders, are still poorly understood. Targeting estrogen receptor α (ERα), this study for the first time evaluated the lipid metabolic effects of NPAHs using in vitro and in vivo models. The results indicated that four of the five NPAHs tested exhibited significant ERα agonistic activities, and induced increased secretion of 17β-estradiol (E₂) in HepG2 cells. Furthermore, lipidomic analysis showed that exposure to the candidate NPAH (3-nitrofluoranthene, 3-NFA) led to elevated hepatic levels of triacylglycerols (TAGs) and cholesteryl esters (CEs). Importantly, the lipid overload induced by 3-NFA was verified in the livers of zebrafish larvae using Oil Red O staining. Additionally, significant increases in E₂ production and the expression levels of associated genes (17βHSD and C/EBP-α) further supported the involvement of the ERα signaling pathway in the lipid metabolic perturbation induced by 3-NFA. These results provide novel insight into the lipid metabolism-disrupting effects induced by NPAHs and may offer a better understanding of the environmental risks of NPAHs.

Short and medium-chain chlorinated paraffins in serum from residents aged from 50 to 84 in Jinan, China: Occurrence, composition and association with hematologic parameters

Human exposure to chlorinated paraffins (CPs) has been expected and assessed by external pathways considering their pervasive environmental occurrence. However, the deficiency of external exposure assessment in characterizing human burden is unavoidable. In addition, the associations between health outcomes and CP contents in human biospecimen are rarely assessed. In this study, we reported the occurrence and homologue profiles of short-chain chlorinated paraffins (SCCPs) and medium-chain chlorinated paraffins (MCCPs) in serum samples from 145 residents aged from 50 to 84 in Jinan, Shandong Province of China using quadrupole time-of-flight high-resolution mass spectrometry coupled with atmospheric pressure chemical ionization source operated in negative ion mode (APCI-qTOF-HRMS). The associations between serum CP concentrations and hematologic parameters were further analyzed by linear regression. We identified high level of ∑SCCPs (median = 107 ng/g wet weight, ww; 13,800 ng/g lipid, lw), ∑MCCPs (median = 134 ng/g ww; 15,200 ng/g lw) and elevated ∑MCCPs/∑SCCPs (median = 1.12) in serum of the studied population. C₁₃-CPs and C₁₄-CPs were the most abundant SCCP and MCCP groups, respectively. While the predominant chlorine homologues among SCCPs and MCCPs were Cl_7-8-CPs. ∑SCCPs, ∑MCCPs, ∑MCCPs/∑SCCPs and the homologue patterns presented no significant variance among age, sex and BMI groups. Further explorations suggested that perturbation of hematologic homeostasis could be induced by CP exposure in a sex-specific way, reflected by significant negative associations of serum SCCP and MCCP concentrations in lipid weight basis with sex-specific hematologic parameters. This study suffered from some limitations and should be interpreted with caution. However, the CP burdens of residents in China and the subsequent health risks must be underscored.

Mechanistic in silico modeling of bisphenols to predict estrogen and glucocorticoid disrupting potentials

Endocrine disrupting chemicals (EDCs) can act as agonists, antagonists or mixed agonists/antagonists toward estrogen receptor α (ERα) and glucocorticoid receptor (GR) in a tissue- and cell-specific manner. However, the activation/inhibition mechanism by which structurally different chemicals induce various types of disruption remain ambiguous. This unrevealed theory limited the in silico modeling of EDCs and the prioritization of potential EDCs for experimental testing. As a kind of chemical widely used in manufacture, bisphenols (BPs) have attracted great attentions on their potential endocrine disrupting effects. BPs used in this study exhibited pure agonistic, pure antagonistic or mixed agonistic/antagonistic activities toward ERα and/or GR. According to the mechanistic modeling, the pure agonistic and pure antagonistic activities were attributed to a single type of protein conformation induced by BPs-ERα and/or BPs-GR interactions, whereas the mixed agonistic/antagonistic activities were attributed to multiple conformations that concomitantly exist. After interacting with BPs, the active conformation recruits coactivator to induce agonistic activity and the blocked conformation inhibits coactivator to induce antagonistic activity, whereas the concomitantly-existing multiple conformations (active, blocked and competing conformations) recruit coactivator, recruit corepressor and/or inhibit coactivator to dually induce the agonistic and antagonistic activities. Therefore, the in silico modeling in this study can not only predict ERα and GR disrupting activities but also, especially, identify the potential mechanisms. This mechanistic study breaks the current bottleneck of computational toxicology and can be widely used to prioritize potential estrogen/glucocorticoid disruptor for experimental testing in both pre-clinic and clinic studies.

Distributions and Congener Group Profiles of Short-Chain and Medium-Chain Chlorinated Paraffins in Cooking Oils in Chinese Markets

Chlorinated paraffins (CPs) are organic pollutants that have caused widespread concerns in recent years. Because of their lipophilic characteristics, CPs may enter into the body through diet or other routes and exert adverse effects on human health. In this study, we investigated the occurrence and congener profiles of short-chain chlorinated paraffins (SCCPs) and medium-chain chlorinated paraffins (MCCPs) in 176 cooking oils and 19 oil containers collected from various markets in China. The concentrations of SCCPs and MCCPs in cooking oils were in the range of not detected (ND) to 16,055 ng/g and ND to 11,612 ng/g, respectively, and the geomean concentrations of MCCPs were lower than those of SCCPs. The concentrations of CPs in sesame oil, rapeseed oil, and camellia oil were higher than those in other types of oils, and different oil processing methods had different effects on the presence of CPs in the oils. CPs were detected in 5 out of 20 oil containers, although their concentrations were much lower than those detected in the oil samples, indicating that containers are not the main sources of CPs detected in the oils. The mean SCCP and MCCP intakes through cooking oils of the general Chinese population were 8.83 and 6.09 μg/kg/d, respectively.

Assessment of endocrine-disrupting effects of emerging polyhalogenated carbazoles (PHCZs): In vitro, in silico, and in vivo evidence

Polyhalogenated carbazoles (PHCZs) are an emerging class of persistent, bioaccumulative compounds that are structurally and chemically related to dioxins. They have been detected widely in sediment, river, and soil samples, but their environmental risks are largely unknown. Therefore, seven common PHCZs were tested for their endocrine disrupting potential in silico, in vitro, and in vivo. A dual-luciferase reporter gene assay was used to detect receptor-mediated (agonist or antagonistic) activity (concentration range: 10^-9-10^-5 M) against the estrogen receptor α (ERα), glucocorticoid receptor α (GRα), and mineralocorticoid receptor (MR). The alterations in the steroidogenesis pathway were investigated in H295R cells. Antagonistic effects against GRα were observed with five PHCZs, along with an increase in the cortisol levels of H295R cells. The most common effect observed was that of the agonistic activity of ERα, with the molecular docking analysis further indicating that hydrogen bonding and hydrophobic interactions may stabilize the interaction between PHCZs and the estrogen receptor binding pocket. In addition, a seven-day exposure of young female rats to three PHCZs (27-BCZ, 3-BCZ, and 36-BCZ) resulted in changes in serum E2 levels, uterine epithelium cell heights, and relative uterus weights. In conclusion, endocrine-disrupting effects, especially the estrogenic effects, were observed for the tested PHCZs. Such adverse effects of PHCZs on humans and wildlife warrant further thorough investigation.

Metabolomic profiles of the endangered St. Lawrence Estuary beluga population and associations with organohalogen contaminants

The endangered beluga (Delphinapterus leucas) population residing in the St. Lawrence Estuary (SLE; Eastern Canada) is declining. The elevated tissue concentrations of a wide range of organohalogen contaminants might play a role in the non-recovery of this whale population. Organohalogens have been reported to impair the regulation of several metabolic products from cellular reactions in mammals such as amino acids and fatty acids. The objective of this study was to investigate a suite of organohalogens including polychlorinated biphenyls, organochlorine pesticides, short-chain chlorinated paraffins (SCCPs), polybrominated diphenyl ethers, and selected emerging flame retardants in blubber (biopsy) collected from 40 SLE male belugas, and their relationships to skin concentrations of targeted metabolites (i.e., 21 amino acids, 22 biogenic amines, 18 fatty acids, and 17 energy metabolites). A cluster analysis based on metabolomic profiles distinguished two main subgroups of belugas in the upper and lower sector of their summer habitat in the SLE. These results indicate that ecological factors such as local prey availability and diet composition played a role in shaping the metabolite profiles of belugas. Moreover, SCCP concentrations in SLE male belugas correlated negatively with those of four unsaturated fatty acids (C16:1ω7, C22:5ω3c1, C22:5ω3c2, and C22:6ω3), and positively with those of acetylornithine (biogenic amine). These findings suggest that biological functions such as lipid metabolism represent potential targets for organohalogens in this population, and further our understanding on potential health risks associated with elevated organohalogen exposure in cetaceans. Our results also underscore the necessity of considering ecological factors (e.g., diet and habitat use) in metabolomic studies.

Microplastics and pollutants in biosolids have contaminated agricultural soils: An analytical study and a proposal to cease the use of biosolids in farmlands and utilise them in sustainable bricks

Treated waste-water sludge (biosolids) are frequently recycled in agricultural lands; however, this practice has polluted soils with microplastics (MPs), nanoplastics (NPs), synthetics, heavy metals, pharmaceuticals and engineered nanoparticles. This study analyses many of the significant research outcomes in this area and proposes the urgent reduction of biosolids recycling in farmlands, aiming to eliminate their use altogether as soon as practicable, and instead, to utilise this material as a source of brick firing energy in the manufacturing of fired clay bricks and as a replacement for virgin brick soil. Based on a comprehensive data analysis, this study has calculated that in the European Union, the United States, China, Canada and Australia, approximately 26,042, 21,249, 13,660, 1,518 and 1,241 tonnes of microplastics, respectively, are added to farmlands annually as a result of biosolids application. The accumulation of microplastics produces detrimental effects on soil organisms and increases the accumulation of other micropollutants, such as heavy metals. The degradation of MPs over time is a source for the creation of nanoplastics, which pose a greater threat to ecosystems and human and animal health, as their size allows for their absorption into plant cells. On the other hand, the results of a comprehensive study at RMIT, including a comprehensive Life-Cycle Assessment, confirm that recycling biosolids in fired clay bricks (Bio-Bricks) is a promising sustainable alternative. This study proposes the mandatory addition of 7% biosolids in all brick manufacturing worldwide to utilize all biosolids production in fired clay bricks. This will reduce brick firing energy by over 12.5%.

New Insights in the Endocrine Disrupting Effects of Three Primary Metabolites of Organophosphate Flame Retardants

Despite the ubiquity of organophosphate flame retardants (OPFRs) metabolites in the biota, the endocrine disrupting potency has not been well examined. Herein, we chose three primary metabolites of OPFRs (BCIPP, BDCIPP, and DPHP) to investigate their potential endocrine disrupting effects by in vitro, in vivo, and in silico assays. Three metabolites were agonistic to rat estrogenic receptor alpha (ERα) and antagonists to human mineralocorticoid receptor (MR). BCIPP exerted endocrine disrupting effect contrasting to the negative response of its parental compound. It also poses the strongest binding capacity to ERα among the tested compounds. Both BCIPP and BDCIPP upregulated the genes encoded for estrogenic synthesis enzymes in H295R cells, including 17βHSD and CYP19. All three compounds stimulated the transcription of CYP11B1, whereas BCIPP and DPHP also triggered CYP11B2, encoding for corticoid production. BDCIPP inhibits genes for progesterone synthesis including CYP11A1, STAR, and 3-βHSD. The induction of mortality and low hatchability of zebrafish embryo were ranked as BCIPP ≥ BDCIPP > DPHP. All compounds lead to malformation of zebrafish larvae. Both of the hypothalamic-pituitary-adrenocortical and hypothalamic-pituitary-gonadal axes were disrupted, with the highest impact by BCIPP. Altogether, the data clarified OPFRs metabolites may produce comparable or even higher endocrine disrupting effects than OPFRs.

The potential endocrine disruption of pesticide transformation products (TPs): The blind spot of pesticide risk assessment

The ecological and health risk assessment of environmental pesticide residues have attracted ever-growing attention; however, their transformation products (TPs) have seldom been considered. Herein, we examined the endocrine-disrupting effects of 4 widely used pesticides as pyriproxyfen (Pyr), malathion (ML), benalaxyl (BX), and fenoxaprop-ethyl (FE), together with their 21 TPs through in vitro and in silico approaches, and found approximately 50% of the TPs exhibited stronger endocrine-disrupting effects than their corresponding parent compounds. Specifically, Pyr and 9 TPs (five TPs of Pyr, one of ML, one of BX, and two of FE) exhibited estrogen-disrupting effects, which were also confirmed by results of E-screen and pS2 expression assays, and molecular docking showed that certain hydroxylated TPs could well mimic the binding mode of estrogen with ERα. Meanwhile, two TPs of Pyr, ML and its TP demonstrated weak glucocorticoid antagonistic activities partially contributed by hydrogen bonds. We also discovered that in H295R cells, all the endocrine disruptors increased hormone secretion and the related gene expression levels. Conclusively, since an increasing number of pesticide TPs have been being detected in various environmental media, a more comprehensive understanding of the ecological risk of pesticide TPs is imperative for risk assessments more extensively and regulatory policy-making on pesticide restriction in the future.

Fenvalerate triggers Parkinson-like symptom during zebrafish development through initiation of autophagy and p38 MAPK/mTOR signaling pathway

Fenvalerate (FEN), one of the most used synthetic pyrethroids, has the potential to interfere with human neural function. However, far too little attention was paid to the mechanism of FEN-induced neurotoxicity. Thus we exposed zebrafish to FEN from 4 to 120 h post fertilization (hpf), and analyzed the morphology and behavior of zebrafish. Our results showed that FEN decreased the survival rate of zebrafish, with increased malformation rates and abnormal behaviors. Furthermore, we found typical parkinson-like symptoms in FEN-exposed zebrafish with increases in parkinson's disease (PD), ubiquitin, and Lewy bodies-relevant genes. We also observed the loss of dopaminergic neurons in both FEN-exposed zebrafish and PC12 cells, which were all associated with PD-like symptoms. Besides, FEN activated autophagy by the enhanced expressions of p-mTOR, and LC3-II but the reduction of p62. Further, FEN initially activated p-p38 MAPK followed by p-mTOR, which triggered the transcription of genes responsible for autophagy process and prompted the Lewy bodies neuron generation leading to the PD-like symptoms. This process was inhibited by both 3-methyladenine (3-MA, an autophagy inhibitor) and SB203580 (a p38 MAPK selective inhibitor) in zebrafish and PC12 cells. These results suggest that FEN might cause parkinson-like symptom during zebrafish development through induction of autophagy and activation of p38 MAPK/mTOR signaling pathway. The study revealed the potential mechanism of FEN-induced neurotoxicity and should give new insights into a significant environmental risk factor of developing parkinson's disease.