Acute and subacute oral toxicity of polychlorinated diphenyl sulfides in mice: determining LD50 and assessing the status of hepatic oxidative stress

Acute and subacute hepatotoxicity of genipin in mice and its potential mechanism

Gardenia, as a medicinal and edible herb, has the pharmacological activity of protecting the liver and cholagogue, but the hepatotoxicity induced by the chemical component genipin (GP) limits its application. The aim of this study was to evaluate the acute and subacute hepatotoxicity of genipin in normal mice and mice with α-naphthalene isothiocyanate (ANIT)-induced liver injury. The results of the acute study showed that the LD50 of genipin was 510 mg/kg. Genipin exhibited hepatotoxicity in normal and jaundiced mice at doses of 125 mg/kg, 250 mg/kg, and 500 mg/kg, which increased with dose. In a 28-day subacute study, the 50 mg/kg and 100 mg/kg dose groups showed some pharmacodynamic effects at 7 days but exhibited hepatotoxicity that increased with time and improved after drug withdrawal. In addition, based on proteomics, the mechanism of liver injury induced by genipin may be related to the disruption of the UDP-glucuronosyltransferase system and cytochrome P450 enzyme activity. In conclusion, this study showed that genipin hepatotoxicity was time- and dose dependent, but it is worth mentioning that hepatotoxicity was reversible. It is hoped that this study will provide a scientific basis for circumventing the adverse effects of genipin.

Comparative studies of transformation behaviors and mechanisms of halophenols in multiple chemical oxidative systems

Due to wide applications, halophenols (HPs), especially bromophenols, chlorophenols, and fluorophenols, are commonly detected but resistant to biological removal in wastewater treatment plants (WWTPs). This study investigated the overall transformation behaviors of three representative HPs (2,4-dichlorophenol: 24-DCP, 2,4-dibromophenol: 24-DBP, 2,4-difluorophenol: 24-DFP) in six chemical oxidative systems (KMnO₄, K₂FeO₄, NaClO, O₃, UV, and persulfate (PS)). The results revealed fast removal of selected HPs by O₃, PS and K₂FeO₄, while a large discrepancy in their removal efficiencies occurred under UV irradiation, KMnO₄ oxidation and particularly chlorination. Based on the analysis of the identified intermediates and products, coupling among the five routes was the general route, and dimers were the main intermediates for HP oxidation. The effect of the halogen atom on the transformation pathways of HPs was highly reaction type dependent. Among the six chemical treatments, PS could induce HPs to yield relatively low-molecular-weight polymers and obtain the highest coupling degree. Transition state (TS) calculations showed that the H atom linked to the phenoxy group of HPs was the most easily abstracted by hydroxyl radicals to form the coupling precursor, i.e., phenoxy radicals. This high coupling behavior further resulted in the increased toxicity to green algae. Characterization revealed that HP reaction solutions treated with PS had a severely negative effect on algae growth, photosynthetic pigment synthesis, and the antioxidant enzyme system. These findings can shed light on the reaction mechanisms of advanced oxidation technologies and some risk management and control of PS technique may be considered when treating phenolic pollutants.

Occurrence, partitioning, and bioaccumulation of an emerging class of PBT substances (polychlorinated diphenyl sulfides) in Chaohu Lake, Southeast China

Polychlorinated diphenyl sulfides (PCDPSs) represent an emerging group of constituents that are persistent, bioaccumulative and toxic (PBT) substances of great concern in terms of human health and ecological integrity. However, little is known about the occurrence, environmental behaviour and ecological risks of PCDPSs in lake environments. In this study, the concentrations of 21 PCDPSs were determined in surface water, suspended particulate matter (SPM), sediments, and 8 fish species from Chaohu Lake, China. Eighteen PCDPS congeners were prevalently detected in the samples, with concentrations ranging from 0.272-1.69 ng/L (water), 0.477-2.03 ng/g d.w. (SPM), 0.719-4.07 ng/g d.w. (sediment) and 0-0.131 ng/g w.w. (fish), respectively. Medium- and high-chlorinated PCDPSs in SPM and sediment were significantly higher than those in water samples. Increased PCDPS concentrations were found in higher trophic level fishes and those with a demersal habitat preference, indicating their bioaccumulation and biomagnification potential. The logBCFs, BSSAFs, and BSAFs of PCDPS congeners in fishes were determined to be 3.91-5.18, 0.0500-2.33, and 0.0360-4.94 L/kg, respectively. The organic carbon normalized partition coefficients (logK_oc) of PCDPSs in surface water-SPM (4.61-5.54 L/g) and surface water-sediment (4.38-5.69 L/g) systems were determined, and it was found that highly chlorinated PCDPSs were more prone to migrate from water to sediment and SPM. The toxic equivalent (TEQ) values of PCDPSs in the samples (lower than 10^-1 pg/g or pg/L) and daily intake via fish consumption (0.180-0.340 μg/kg/day) were estimated for humans, and cumulative risk quotients (RQs) after correction at ten sampling sites (0.065-0.66) were calculated for green algae. The findings elucidated the environmental behaviour of PCDPSs in Chaohu Lake.

Novel Functional Food from an invasive species Polygonum cuspidatum: Safety evaluation, Chemical Composition, and Hepatoprotective Effects

Accidentally, we found that the shoots of Polygonum cuspidatum (SPC) have been consumed for centuries as a traditional vegetable in the Shennongjia region of China. Local residents believe that SPC has biological effects such as antibacterial, anti-aging, and antioxidant. To provide scientific support for the use of SPC as a functional food, SPC was evaluated in terms of safety, chemical composition, antioxidant activity both in vivo and in vitro. In the first, SPC exhibited no adverse cytotoxic effects or acute toxicity in mice. Then the chemical composition of SPC was determined by UHPLC-ESI-QTOF-MS/MS. 22 compounds were identified from the SPC extracts, including phenolic, flavonoid, stilbene, and anthraquinone. Finally, an acute ethanol-induced oxidative stress model in mice showed hepatoprotective effects. In brief, our study indicated that SPC is a safe, multi-functional food with antioxidant and hepatoprotective activities. Importantly, the consumption of SPC as a functional food provides a novel strategy of efficient utilization of the invasive plant.

The aryl hydrocarbon receptor: A predominant mediator for the toxicity of emerging dioxin-like compounds

The aryl hydrocarbon receptor (AHR) is a member of the basic helix-loop-helix/Per-ARNT-Sim (bHLH-PAS) family of transcription factors and has broad biological functions. Early after the identification of the AHR, most studies focused on its roles in regulating the expression of drug-metabolizing enzymes and mediating the toxicity of dioxins and dioxin-like compounds (DLCs). Currently, more diverse functions of AHR have been identified, indicating that AHR is not just a dioxin receptor. Dioxins and DLCs occur ubiquitously and have diverse health/ecological risks. Additional research is required to identify both shared and compound-specific mechanisms, especially for emerging DLCs such as polyhalogenated carbazoles (PHCZs), polychlorinated diphenyl sulfides (PCDPSs), and others, of which only a few investigations have been performed at present. Many of the toxic effects of emerging DLCs were observed to be predominantly mediated by the AHR because of their structural similarity as dioxins, and the in vitro TCDD-relative potencies of certain emerging DLC congeners are comparable to or even greater than the WHO-TEFs of OctaCDD, OctaCDF, and most coplanar PCBs. Due to the close relationship between AHR biology and environmental science, this review begins by providing novel insights into AHR signaling (canonical and non-canonical), AHR's biochemical properties (AHR structure, AHR-ligand interaction, AHR-DNA binding), and the variations during AHR transactivation. Then, AHR ligand classification and the corresponding mechanisms are discussed, especially the shared and compound-specific, AHR-mediated effects and mechanisms of emerging DLCs. Accordingly, a series of in vivo and in vitro toxicity evaluation methods based on the AHR signaling pathway are reviewed. In light of current advances, future research on traditional and emerging DLCs will enhance our understanding of their mechanisms, toxicity, potency, and ecological impacts.

Acute toxicity of polychlorinated diphenyl ethers (PCDEs) in three model aquatic organisms (Scenedesmus obliquus, Daphnia magna, and Danio rerio) of different trophic levels

The frequent detection of polychlorinated diphenyl ethers (PCDEs) in aquatic systems has aroused widespread concerns, however, their potential hazard to aquatic ecosystems has been poorly understood. Here the acute toxicity of 12 PCDE congeners was evaluated in three model aquatic organisms representing different trophic levels following OECD test guidelines, including green algae (Scenedesmus obliquus), water flea (Daphnia magna), and zebrafish (Danio rerio). Dose-dependent increases in growth inhibition and mortality were observed for all tested PCDE congeners. Most of the PCDE congeners, in particular 3,3',4,4'-tetra-CDE, were highly toxic to the three aquatic organisms with EC₅₀ or LC₅₀ values below 1 mg L^-1. Their toxicities were generally comparable with those of certain polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs). Moreover, D. magna was the most sensitive species among the three aquatic organisms. In addition, the EC₅₀ or LC₅₀ values had an extremely significant correlation with the n-octanol-water partition coefficient (logK_ow) of the PCDE congeners. The established quantitative structure-property relationship (QSPR) models indicated that the molecular polarizability (α) could significantly influence the acute toxicity of PCDEs on Daphnia magna and Danio rerio, and the energy of the lowest unoccupied molecular orbital (E_LUMO) is the key factor of the acute toxicity of PCDEs in Scenedesmus obliquus. In addition, even at environmental levels, 3,3',4,4'-tetra-CDE could induced seveve oxidative damages in the three aquactic species. These findings would contribute to the understanding of adverse effects of PCDEs in aquatic organisms.

Improved up-and-down procedure for acute toxicity measurement with reliable LD50 verified by typical toxic alkaloids and modified Karber method

Background

Up-and-down procedure (UDP) was recommended to replace traditional acute toxicity methods. However, it was limited due to the long experimental period (20–42 days). To improve UDP, an improved UDP method (iUDP) was developed by shortening observation time between sequence dosages. The aim of this study was to test the reliability of iUDP to provide a reliable method for the acute toxicity measurement of valuable or minor amount compounds.

Methods

Oral median lethal dose (LD₅₀) of nicotine, sinomenine hydrochloride and berberine hydrochloride were measured both by iUDP and modified Karber method (mKM).

Results

LD₅₀ of the three alkaloids measured by iUDP with 23 mice were 32.71 ± 7.46, 453.54 ± 104.59, 2954.93 ± 794.88 mg/kg, respectively. LD₅₀ of the three alkaloids measured by mKM with 240 mice were 22.99 ± 3.01, 456.56 ± 53.38, 2825.53 ± 1212.92 mg/kg, respectively. The average time consumed by the two methods were 22 days and 14 days respectively. Total grams of the alkaloids used by the two methods were 0.0082 and 0.0673 (nicotine), 0.114 and 1.24 (sinomenine hydrochloride), 1.9 and 12.7 (berberine hydrochloride).

Conclusion

iUDP could replace mKM to detect acute toxicity of substances with comparable and reliable result. And it is suitable for valuable or minor amount substances.

Polychlorinated Diphenyl Sulfides: An Emerging Class of Persistent, Bioaccumulative, and Toxic Substances in the Environment

Polychlorinated diphenyl sulfides (PCDPSs) have recently attracted increasing attention due to their potential adverse effects on human and ecosystem health. We present a review regarding their environmental occurrence, persistence, bioaccumulation, toxicity, and biotransformation. The existing literature demonstrates that PCDPSs are ubiquitous in various environmental matrices, are persistent in the environment, and have long-range transport potential. In addition, the high bioaccumulation potential of these emerging pollutants, especially the low chlorinated PCDPS congeners, has been confirmed based on both theoretical calculations and experimental investigations. Moreover, a spectrum of adverse effects, such as acute liver injury, retardation of development, reproductive disorders, and increased mortality have been widely reported in vertebrates. These adverse outcomes were associated with oxidative stress and activation of aryl hydrocarbon receptors. Given these findings, PCDPSs represent candidate persistent, bioaccumulative, and toxic substances and thus deserve further research to fully elucidate their environmental behavior and fate, and evaluate the risks to human and ecosystem health. Environ Toxicol Chem 2021;40:2657-2666. © 2021 SETAC.

Effects of common inorganic anions on the ozonation of polychlorinated diphenyl sulfides on silica gel: Kinetics, mechanisms, and theoretical calculations

In this work, the ozonation properties of 2,2',3',4,5-pentachlorodiphenyl sulfide (PeCDPS) was systematically studied, with special emphasis on the underlying mechanism for the effects of inorganic ions. Kinetic experiments show that common ions can significantly reduce the oxidative properties of ozone, except for SO₃^2- and Cu²⁺. The inhibition effect of anions has been explained through the scavenging effect of free radicals and the generation of other free radicals with weaker oxidation potentials, but no research has reported on the effect of free radicals generated by anions on the degradation pathway. However, SO₃^2- and Cu²⁺ exerted a promoting effect through enhanced formation of ·OH via the hydrolysis effect and the catalyzed decomposition of O₃, respectively. According to the intermediate products identified by high performance liquid chromatography-mass spectrometry/mass spectrometry (HPLC-MS/MS) analysis, direct oxidation of S atom, substitution of Cl atom with -OH group, and hydroxylation of the benzene ring were commonly observed. The addition of NO₂^- and SO₃^2- produced new free radicals like ·NO₂, ·SO₃ and ·SO₄^-, which would attack the parent compound or its primary product, thus influencing the degradation efficiency and pathways. The radicals initiated reactions and the structures of the corresponding products were further rationalized by density functional theory (DFT) calculations. These findings provide new insights into the effects of common anions on ozone oxidation of organic compounds.

Acute oral toxicity test and assessment of combined toxicity of cadmium and aflatoxin B1 in kunming mice

Cadmium and aflatoxin B₁ (AFB₁) are both common and widespread pollutants in food and feed. There are several reports on toxicity induced by Cadmium or AFB₁ alone, but few address the toxicity caused by co-exposure to the two substances. In this study, 42 female and 42 male Kunming (KM) mice were divided into seven groups to test the acute oral toxicity of CdCl₂ and AFB₁, using Karber's method. The combined toxicity was assessed using the Keplinger evaluation system. Acute toxicity symptoms, deaths, and body and organ weights were evaluated, and hematological, blood biochemical, and histopathological analyses were conducted. The results revealed the following median lethal doses (LD₅₀): LD_{50(Female KM mice)} = 62.56 mg/kg; LD_{50(Male KM mice)} = 48.79 mg/kg; LD_{50(KM mice)}=55.27 mg/kg. The combined toxicity of AFB₁ and CdCl₂ showed an additive effect in mice, and an increase in the mixed dose of AFB₁ and CdCl₂ resulted in greater toxicity. These results demonstrated that the combined toxicity of AFB₁ and CdCl₂ was greater than the toxicities of the individual components in mice; thus, this may cause particular challenges when addressing these hazards in food and feed and the associated risk to human and animal health.

Polychlorinated diphenyl sulfides can induce ROS and genotoxicity via the AhR-CYP1A1 pathway

Polychlorinated diphenyl sulfides (PCDPSs) are a group of chemicals that can interact and activate the aryl hydrocarbon receptor (AhR). Previous studies have shown that PCDPSs can cause oxidative stress in livers. However, information on genotoxicity of PCDPSs is limited. In this study, it is hypothesized that PCDPSs can produce reactive oxygen species (ROS) by activating the AhR and inducing expression of CYP1A1, which subsequently causes genotoxicity. HepG2 cells (transfected with AhR and CYP1A1 siRNA or not) were exposed to six PCDPSs. ROS and expression of five genes were measured to confirm relationships between genotoxicity and signaling along AhR pathway. After 24 h, a significant concentration-dependent ROS was observed. Production of ROS varied with the number of Cl atoms. And the formation of ROS decreases with the increase of the number of Cl atoms, which was consistent with results observed for polychlorinated biphenyls (PCBs). Most of the tested PCDPSs up-regulated expression of CYP1A1 enzyme via signaling AhR pathways. The exposure to 2,3',4,5-tetra-CDPS at 10 μM up-regulated the CYP1A1 mRNA in HepG2 cells to 29-fold. Expression of CYP1A1 mRNA was related to the number of substituted Cl, probably due to the stronger ability of more chlorinated PCDPSs to bind to and activate the AhR. However, there was no significant quantitative relationship between expression of CYP1A1 and concentrations of ROS, probably due to other oxidases' influence. Furthermore, PCDPSs also caused induction of OGG1 and XRS2 more than 2 times, indicates oxidation of bases and breaks of strands. The transfection of cells with siRNA to silence expression of the CYP1A1 gene results in ROS at background levels, further supporting the proposed mechanism PCDPSs inducing ROS and DNA damage via the AhR-mediated pathway.

Tissue-specific bioaccumulation, depuration and metabolism of 4,4'-dichlorodiphenyl sulfide in the freshwater mussel Anodonta woodiana

Polychlorinated diphenyl sulfides (PCDPSs) are considered as a class of sulfur-containing dioxin-like pollutants with ubiquitous occurrence in natural waters and potential ecotoxicity to aquatic organisms. However, to date, no information is available regarding the bioaccumulation and biotransformation of PCDPSs in aquatic species. In this study, the uptake and depuration kinetics of 4,4'-dichlorodiphenyl sulfide (4,4'-di-CDPS) in the freshwater mussel Anodonta woodiana were investigated through semi-static exposure. The uptake rates (k₁), depuration rates (k₂), biological half-lives (t_1/2) and tissue-specific bioconcentration factors (BCFs) of 4,4'-di-CDPS in the gill, liver and muscle were measured in the range of 0.509-21.734 L d^-1 g^-1 d.w., 0.083-0.221 d^-1, 3.14-8.35 d and 3.662 × 10³-124.979 × 10³ L kg^-1 l.w., respectively. With the increase in exposure dose, the values of k₁ and BCFs were significantly reduced, indicating that low-dose exposure to 4,4'-di-CDPS could lead to more severe bioaccumulation. Based on the analysis of mass spectra of the extracted liver samples, the structures of four metabolites of 4,4'-di-CDPS were identified. Moreover, the levels of these metabolites were also quantitatively measured. The proposed metabolic pathways of 4,4'-di-CDPS in mussel liver included sulfur-oxidation, dechlorination and methoxylation. Comparatively, sulfur-oxidation was the predominant metabolic pathway of 4,4'-di-CDPS in the liver of A. woodiana. These results provide valuable data and fill the information gap on the bioaccumulation and metabolism of PCDPSs in freshwater species.

Down-Regulation of hspb9 and hspb11 Contributes to Wavy Notochord in Zebrafish Embryos Following Exposure to Polychlorinated Diphenylsulfides

It is hypothesized that key genes, other than ahr2, are present and associated with the development of a unique type of notochord malformation known as wavy notochord in early life stages of zebrafish following exposure to polychlorinated diphenylsulfides (PCDPSs). To investigate the potential mechanism(s), time-dependent developmental morphologies of zebrafish embryos following exposure to 2500 nM 2,4,4',5-tetra-CDPS, 2,2',4-tri-CDPS or 4,4'-di-CDPS were observed to determine the developmental time point when notochord twists began to occur (i.e., 21 h-postfertilization (hpf)). Simultaneously, morphometric measurements suggested that PCDPS exposure did not affect notochord growth at 21 or 120 hpf; however, elongation of the body axis was significantly inhibited at 120 hpf. Transcriptome analysis revealed that the retardation of body growth was potentially related with dysregulation of transcripts predominantly associated with the insulin-associated Irs-Akt-FoxO cascade. Moreover, knockdown and gain-of-function experiments in vivo on codifferentially expressed genes demonstrated that reduced expression of hspb9 and hspb11 contributed to the occurrence of wavy notochord. The results of this study strongly support the hypothesis that the notochord kinks and twists are triggered by the down-regulation of hspb9 and hspb11, and intensified by body growth retardation along with normal notochord length in PCDPS-exposed zebrafish embryos.

Ferrate(VI) oxidation of polychlorinated diphenyl sulfides: Kinetics, degradation, and oxidized products

This paper presents oxidation of polychlorinated diphenyl sulfides (PCDPSs), dioxin-like compounds, by ferrate(VI) (Fe^VIO₄^2-, Fe(VI)). Kinetics of the reactions of Fe(VI) with seventeen PCDPSs, differ in number and positions of chlorine atoms (from 2 to 7), were investigated at pH 8.0. The second-order rate constants (k, M^-1 s^-1) of the reactions varied with the numbers and positions of chlorine atoms and appeared to be related with standard Gibbs free energy of formation (Δ_fG⁰) of PCDPSs. Degradation experiments in the presence of ions and humic acid demonstrated complete removal of PeCDPS by Fe(VI) in minutes. Pathways of the reaction were investigated by identifying oxidized products (OPs) of the reaction between Fe(VI) and 2,2',3',4,5-pentachlorodiphenyl sulfide (PeCDPS) at pH 8.0. Pathways of oxidation involved major pathway of attack on sulfur(II) by Fe(VI) in steps to yield sulfoxide type products, and subsequent breakage of C-S bond with the formation of sulfonic acid-containing trichloro compound. Minor pathways were hydroxylation of benzene ring and substitution of chlorine atom with hydroxyl group. Estimation of toxicity of OPs of the oxidation of PeCDPS by Fe(VI) suggested the decreased toxicity from the parent contaminant.

Activation of AhR-mediated toxicity pathway by emerging pollutants polychlorinated diphenyl sulfides

Polychlorinated diphenyl sulfides (PCDPSs) are a group of environmental pollutants for which limited toxicological information is available. This study tested the hypothesis that PCDPSs could activate the mammalian aryl hydrocarbon receptor (AhR) mediated toxicity pathways. Eighteen PCDPSs were tested in the H4IIE-luc transactivation assay, with 13/18 causing concentration-dependent AhR activation. Potencies of several congeners were similar to those of mono-ortho substituted polychlorinated biphenyls. A RNA sequencing (RNA-seq)-based transcriptomic analysis was performed on H4IIE cells treated with two PCDPS congeners, 2,2',3,3',4,5,6-hepta-CDPS, and 2,4,4',5-tetra-CDPS. Results of RNA-seq revealed a remarkable modulation on a relatively short gene list by exposure to the tested concentrations of PCDPSs, among which, Cyp1 responded with the greatest fold up-regulation. Both the identities of the modulated transcripts and the associated pathways were consistent with targets and pathways known to be modulated by other types of AhR agonists and there was little evidence for significant off-target effects within the cellular context of the H4IIE bioassay. The results suggest AhR activation as a toxicologically relevant mode of action for PCDPSs suggests the utility of AhR-related toxicity pathways for predicting potential hazards associated with PCDPS exposure in mammals and potentially other vertebrates.

Hepatic oxidative status and metal homeostasis disturbance of 2-hydroxylated dioxin in ICR mice

In the present study, the toxic effects of the oral exposure of 2-hydroxylated dioxin (2-HODD) in ICR male mice were examined. The mice were administered different doses (0.2, 2.0 and 20.0mg/kg) of 2-HODD. After 14 days of exposure, the oxidative stress (OS) indicator levels and the essential metal concentrations in the mouse livers were determined. The results showed that the superoxide dismutase (SOD) and the glutathione peroxidase (GPx) activities were increased in the 0.2mg/kg group, whereas they were significantly decreased in the 2.0 and 20.0mg/kg groups. Decreases in the catalase (CAT) activity and the glutathione (GSH) levels, accompanied by increases in the malondialdehyde (MDA) contents, were recorded in all of the 2-HODD-treated groups. The hepatic iron, copper and zinc levels increased in all of the 2-HODD-treated groups. The histological examination of the livers demonstrated swollen cells and inflammation. Dose-dependent changes in both the OS indicators and the hepatic metal levels were observed. In conclusion, a single low dose of 2-HODD significantly perturbed the hepatic OS status and metals homeostasis in the mice.

Occurrence of polychlorinated diphenyl sulfides (PCDPSs) in surface sediments and surface water from the Nanjing section of the Yangtze River

Polychlorinated diphenyl sulfides (PCDPSs) are dioxin-like compounds that could induce various adverse effects to organisms. However, little is known about the occurrence of PCDPSs in the riverine environment. In the present study, the concentrations of twenty-one types of PCDPSs in the surface sediments and in surface water from the Nanjing section of the Yangtze River were examined. A total of 19 types of PCDPSs were detected and ∑PCDPSs concentrations in surface sediment and surface water ranged from 0.10 to 6.90 ng/g and 0.18 to 2.03 ng/L, respectively. The 2,2',4,4',5-penta-CDPS was the dominant congener in sediment (19.9%) and 2,2',3,3'-tetra-CDPS was the most abundant congener in water (12.2%). The tetra-CDPSs were the dominant congeners both in sediment and in water. Compared with sediment, the percentage of lower chlorinated PCDPSs in water increased distinctly. Source analysis revealed that the PCDPSs in the sediment and in the water mainly came from chemical wastewater rather than domestic sewage. There was a significant linear correlation between ∑PCDPS concentrations and sediment TOC contents, while no linear correlation existed between ∑PCDPS concentrations and water DOC contents. This study demonstrated the prevalent contamination by PCDPSs in sediments and in water from the Nanjing section of the Yangtze River.

Activation of avian aryl hydrocarbon receptor and inter-species sensitivity variations by polychlorinated diphenylsulfides

It was hypothesized that polychlorinated diphenyl sulfides (PCDPSs) can potentially interact with an aryl hydrocarbon receptor (AHR) and thereby cause adverse effects in wildlife like birds. A recently developed avian AHR1-luciferase report gene (LRG) assay was used to assess the interaction between avian AHR1 and 18 PCDPSs and to compare the interspecies sensitivity among chicken, ring-necked pheasant, and Japanese quail by PCDPSs. Most of the tested PCDPSs could activate the AHR1-mediated pathways in avian species, and the relative potency (ReP) of the PCDPSs increased with the increasing number of substituted Cl atoms. The rank orders of PCDPSs potency were generally similar among birds, although the ReP varied. In addition, not all the sensitivity rank orders of avian AHR1 constructs for PCDPSs were consistent with that of TCDD. ReP values of PCDPSs suggested that some PCDPSs like 2,3,3',4,5,6-hexa-CDPS and 2,2',3,3',4,5,6-hepta-CDPS are higher than the avian WHO-TEFs of OctaCDD, OctaCDF, and most of the coplanar PCBs. Our results report for the first time the activation of an AHR1-mediated molecular toxicological mechanism by PCDPSs, and provide the ranking of ReP and relative sensitivity values of different congeners, which could guide the further toxicity test of this group of potential high priority environmental pollutants.

Subacute oral toxicity of BDE-15, CDE-15, and HODE-15 in ICR male mice: assessing effects on hepatic oxidative stress and metals status and ascertaining the protective role of vitamin E

The present study examined the effects of oral exposure of 4,4'-dibromodiphenyl ether (BDE-15), 4,4'-dichlorodiphenyl ether (CDE-15), and 4,4'-dihydroxydiphenyl ether (HODE-15) on hepatic oxidative stress (OS) and metal status in Institute of Cancer Research (ICR) male mice. Furthermore, the role of vitamin E in ameliorating potential OS caused by BDE-15, CDE-15, and HODE-15 was investigated. Three groups of mice were exposed to 1.20 mg/kg(body weight)/day of each of the three toxicants for 28 days. Results showed that none of the three toxicants altered growth rates of mice, but significantly increased (P<0.05) relative liver weights and decreased relative kidney weights. Pathological changes including cell swelling, inflammation and vacuolization, and hepatocellular hypertrophy in livers were observed. Significant decreases (P<0.05 and P<0.01) in superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) activity, and glutathione (GSH) levels, together with increases in malondialdehyde (MDA) content were recorded in all toxicant-treated groups. Hepatic copper levels increased in all toxicant-treated groups. Hepatic zinc levels decreased in the liver of BDE-15-treated mice, whereas they increased in the livers of CDE-15-treated and HODE-15-treated mice. In conclusion, daily exposure to the three toxicants perturbed metal homeostasis and increased OS in mouse liver. Experimental data indicated the hepatic oxidative toxicity of the three toxicants followed the order BDE-15<HODE-15<CDE-15. Moreover, the study proved that daily supplementation of 50 mg/kg vitamin E is effective to ameliorate the hepatic OS status and metal disturbance in mice.

Acute oral toxicity and liver oxidant/antioxidant stress of halogenated benzene, phenol, and diphenyl ether in mice: a comparative and mechanism exploration

The lethal doses (LD50s) of fluorinated, chlorinated, brominated, and iodinated benzene, phenol, and diphenyl ether in mice were ascertained respectively under the consistent condition. The acute toxicity of four benzenes orders in fluorobenzene (FB) < iodobenzene < chlorobenzene≈bromobenzene, that of four phenols orders in 4-iodophenol≈4-bromophenol < 4-chlorophenol (4-MCP) < 4-fluorophenol (4-MFP), and that of four diphenyl ethers orders in 4,4'-iododiphenyl ether < 4,4'-difluorodiphenyl ether < 4,4'-dichlorodiphenyl ether≈4,4'-dibromodiphenyl ether. General behavior adverse effects were observed, and poisoned mouse were dissected to observe visceral lesions. FB, 4-MCP, and 4-MFP produced toxic faster than other halogenated benzenes and phenols, as they had lower octanol-water partition coefficients. Pathological changes in liver and liver/kidney weight changes were also observed. Hepatic superoxide dismutase, catalase activities, and malondialdehyde level were tested after a 28-day exposure, which reflects a toxicity order basically consistent with that reflected by the LD50s. By theoretical calculation and building models, the toxicity of benzene, phenol, and diphenyl ether were influenced by different structural properties.