Evaluation of genotoxicity and hematological effects in common carp (Cyprinus carpio) induced by disinfection by-products

N-nitrosamines induced gender-dimorphic effects on infant rats at environmental levels

The safety of drinking water has always been a concern for people all over the world. N-nitrosamines (NAs), a kind of nitrogenous disinfection by-products (N-DBPs), are generally detected as a mixture in drinking water at home and abroad. Studies have shown that individual NAs posed strong carcinogenicity at high concentrations. However, health risks of NAs at environmental levels (concentrations in drinking water) are still unclear. Therefore, the potential health risks of environmentally relevant NAs exposure in drinking water needs to be conducted. In this study, blood biochemical analysis and metabolomics based on nuclear magnetic resonance (NMR) were performed to comprehensively investigate NAs induced metabolic disturbance in infant rats at environmental levels. Results of blood biochemical indices analysis indicated that AST in the serum of male rats in NAs-treated group exhibited a significant gender-specific difference. Multivariate statistics showed that two and eight significantly disturbed metabolic pathways were identified in the serum samples of NAs-treated male and female rats, respectively. In the urine samples of NAs-treated female rats, glycine, serine, and threonine metabolism pathway was significantly disturbed; while three significantly disturbed metabolic pathways were found in the urine of NAs-treated male rats. Finally, results of spearman correlation coefficients suggested that the disturbances of metabolism profile in serum and urine were correlated with changes in the gut microbiota (data derived from our published paper). Data presented here aimed to generate new health risk data of NAs mixture exposure at environmental levels and provide theoretical support for drinking water safety management. ENVIRONMENTAL IMPLICATION: N-nitrosamines (NAs) are a kind of nitrogenous disinfection by-products (N-DBPs) generated during drinking water disinfection processes. Herein, health risks of NAs at environmental levels (concentrations in drinking water) are investigated using blood biochemical analysis and nuclear magnetic resonance (NMR)-based metabolomics. Results confirmed NAs induced gender-specific on the metabolism in rat and the disturbances of metabolism profile in serum and urine were correlated with changes in the gut microbiota. Data presented here aimed to generate new health risk data of NAs mixture exposure at environmental levels and provide theoretical support for drinking water safety management.

Effective boosting of halogenated α, β-unsaturated C4-dicarbonyl electrocatalytic hydrodehalogenation by 1 T'-MoS2/Ti3C2T2 (T = O, OH, F) heterojunctions: A theoretical study

Halogenated α, β-unsaturated C4-dicarbonyl (X-BDA), a novel family of high-toxicity ring cleavage products, is produced during the disinfection of phenolic compounds. The technique of electrocatalytic hydrodehalogenation (ECH) is efficient in rupturing carbon-halogen bonds and generating useful chemicals. This study used first principles to examine the ECH reaction mechanism of X-BDA and the subsequent hydrogenation reaction of the toxic derivative BDA over the 1 T'-MoS2/Ti3C2T2 (T = O, OH, F) catalysts. The catalytic activity of Ti3C2T2 (T = O, OH, F) catalysts decreases gradually with -OH, -F, -O functional group. The loading of 1 T'-MoS2 onto the Ti3C2T2 surface improves the stability and selectivity of Ti3C2T2. In particular, 1 T'-MoS2/Ti3C2(OH)2 is most conducive to the ECH reaction of X-BDA via a direct-indirect continuous reduction process. It exhibits excellent removal capability towards Cl-BDA, with decreasing reactivity in the order of the Cl-, Br-, and I-BDA. The material offers a solution to the challenging dechlorination issue. The dehalogenated product BDA can be hydrogenated to produce 1,4-butanedial, 1,4-butanediol, and 1,4-butenediol. Three valuable chemicals can be obtained by exerting an applied potential of - 0.65 V. This work suggests that the formation of heterojunction catalyst may lead to new strategies to improve ECH for environmental remediation applications.

Toxicity effects of disinfection byproduct chloroacetic acid to Microcystis aeruginosa: Cytotoxicity and mechanisms

Chlorine-based disinfectants are widely used for disinfection in wastewater treatment. The mechanism of the effects of chlorinated disinfection by-products on cyanobacteria was unclear. Herein, the physiological effects of chloroacetic acid (CAA) on Microcystis aeruginosa (M. aeruginosa), including acute toxicity, oxidative stress, apoptosis, production of microcystin-LR (MC-LR), and the microcystin transportation-related gene mcyH transcript abundance have been investigated. CAA exposure resulted in a significant change in the cell ultrastructure, including thylakoid damage, disappearance of nucleoid, production of gas vacuoles, increase in starch granule, accumulation of lipid droplets, and disruption of cytoplasm membranes. Meanwhile, the apoptosis rate of M. aeruginosa increased with CAA concentration. The production of MC-LR was affected by CAA, and the transcript abundance of mcyH decreased. Our results suggested that CAA poses acute toxicity to M. aeruginosa, and it could cause oxidative damage, stimulate MC-LR production, and damage cell ultrastructure. This study may provide information about the minimum concentration of CAA in the water environment, which is safe for aquatic organisms, especially during the global coronavirus disease 2019 pandemic period.

Molecular interactions between bovine serum albumin (BSA) and trihalophenol: Insights from spectroscopic, calorimetric and molecular modeling studies

The issue of disinfection byproducts (DBPs) in the water has received critical attention due to the health effects on humans. In the water environment, interactions between bovine serum albumins (BSA), the most abundant water-soluble protein, and DBPs unavoidably occur. In this study, comparative binding interactions of two aromatic DBPs - 2,4,6-trichlorophenol (TCP) and 2,4,6-tribromophenol (TBP) with BSA were investigated systematically utilizing fluorescence spectrometry, UV absorption spectrometry, isothermal titration calorimetry and molecular docking approach. The fluorescence quenching results indicated that TCP/TBP could quench the endogenous fluorescence of BSA through static quenching mechanisms, and TBP showed a more substantial quenching effect. The binding constants were determined for TCP-BSA (3.638 × 10⁵ L/mol, 303 K) and TBP-BSA (6.394 × 10⁵ L/mol, 303 K) complexes, with TBP showing higher binding affinity than TCP. The thermodynamic study and docking analysis suggested that hydrogen bonding and van der Waals forces were the primary interaction forces. Both of TCP and TBP were located in the subdomain IIIA of BSA, and TBP could form more stable complex than TCP. The results of the present study contributed valuable information on the environmental behaviors of halophenols in water environment from perspectives of binding with BSA.

Hematological and Biochemical Responses of Newly Formulated Primary Root Canal Obturating Material: An In Vivo Study

Background and objective Any drug or medicinal agent, when implanted into the body, gets biotransformed by various organ systems and the toxic byproducts of this process alter the normal physiological process. In this experimental study, we aimed to quantify the safety of newly formulated primary root canal obturating material by investigating the hematological and biochemical parameters related to liver function. Methodology Forty-eight Wistar rats (weighing 250-350 grams) were classified into three groups (n=16) through random allocation. Preoperative blood samples were collected by puncturing the orbital venous plexus, the values of which were used as control. Zinc oxide eugenol (ZOE), calcium hydroxide iodoform paste (Metapex), and newly formulated triple antibiotic obturating paste (TAOP) were implanted (100 µg) into dorsal connective tissues. Blood samples on the seventh, 15th, and 30th postoperative days were evaluated respectively by analyzing hematological, hepatic, and, renal function tests for acute and chronic inflammatory responses. Results  The intra-group and inter-group comparisons among all the test materials after seven days exhibited high significance in terms of hemoglobin (Hb), mean corpuscular volume (MCV), neutrophils, and serum glutamic-oxaloacetic transaminase (SGOT) (p<0.001), while others showed mixed responses (p<0.05 to p>0.05). After 15 days, the comparisons showed high significance with respect to packed cell volume (PCV), mean cell volume (MCV), and serum creatinine (p<0.001), while others showed significant to nonsignificant differences (p<0.05 to p>0.05). At the end of 30 days, all the parameters showed mixed responses (p<0.001 to p>0.05). Conclusion The newly formulated obturating material TAOP showed lower adverse hematological, hepatic, and renal effects in experimental animals compared to other test materials, with most parameters reverting to normal after 30 days.

Mercuric chloride-induced oxidative stress, genotoxicity, haematological changes and histopathological alterations in fish Channa punctatus (Bloch, 1793)

The present study was undertaken to investigate the adverse effects of mercuric chloride (HgCl₂ ) overload in the fish Channa punctatus. Two sublethal test concentrations of HgCl₂ (1/20th and 1/10th of 96 h LC₅₀ i.e., 0.03 mg l^-1 (low concentration) and 0.07 mg l^-1 (high concentration), respectively, were used for exposure. Blood, liver and kidney tissues of the control and exposed specimens were sampled at intervals of 15, 30, and 45 days to assess alterations in oxidative stress, genotoxicity haematological parameters and histopathology. Significant changes in Hb%, RBC count, WBC count, antioxidant enzyme activity, i.e., superoxide dismutase (SOD), catalase (CAT), glutathione (GSH) and glutathione reductase (GR), were recorded. Micronuclei (MN) induction, nuclear abnormalities (NAs) and histopathological alterations were also observed in the exposed fish. Significant (P < 0.05) increase in the activities of SOD, CAT, GSH and GR was observed. After 45 days, a decrease in the level of GSH and GR was noticed which suggests an undermined anti-oxidative defence system in the fish exposed to HgCl₂ . Histological examination of the liver and kidney showed serious tissue injury and histological alterations. Significant increases in MN and NA frequencies reveal the DNA damage in erythrocytes of fish, and haematological changes show the toxicological potential of HgCl₂ . The observed changes in the antioxidant defence system, genotoxicity and haematological and histological changes in the present study provide the most extensive insight into HgCl₂ stress in C. punctatus.

λ cyhalothrin induced toxicity and potential attenuation of hematological, biochemical, enzymological and stress biomarkers in Cyprinus carpio L. at environmentally relevant concentrations: A multiple biomarker approach

The present study was aimed to evaluate the toxic effects of a commonly used synthetic pyrethroid, λ cyhalothrin on the common carp, Cyprinus carpio L. The results depicted that 96 h LC₅₀ value of λ cyhalothrin to the fish was 1.48 μg l^-1. During 45 days of chronic exposure a significant reduction (p < 0.05) in the RBC, hemoglobin, and hematocrit value of fish was observed in λ cyhalothrin treated fish. Blood glucose, cholesterol and creatinine levels increased significantly, while total protein and albumin were significantly decreased (p < 0.05) in the exposed fish. Moreover, alanine aminotransferase and aspartate aminotransferase levels in the blood also increased significantly (p < 0.05) in the treated fish. In gills and liver, glutathione S-transferase (GST) and glutathione peroxidase (GPx) and in liver GST exhibited a significant initial augmentation followed by a subsequent reduction while catalase (CAT), superoxide dismutase (SOD), and malondialdehyde (MDA) level increased markedly with incrementing concentrations of λ cyhalothrin in both the organs. Acetylcholinesterase (AchE) activity in both gills and liver decreased in exposed fish upon addition λ cyhalothrin. However, the hazardous effects of λ cyhalothrin on C. carpio were characterized and portrayed by the development of integrated biomarker response (IBR), and biomarker response index (BRI). GUTS-SD and IT modeling were implied for a better interpretation of the toxicity. These results indicate that exposure to λ cyhalothrin alters the survivability at the acute level and the activity of hematological, plasma biochemical as well as enzymological and stress parameters (in gills and liver) at the sublethal level in C. carpio.

Occurrence, influencing factors, toxicity, regulations, and abatement approaches for disinfection by-products in chlorinated drinking water: A comprehensive review

Disinfection is considered as a vital step to ensure the supply of clean and safe drinking water. Various approaches are adopted for this purpose; however, chlorination is highly preferred all over the world. This method is opted owing to its several advantages. However, it leads to the formation of certain by-products. These chlorination disinfection by-products (DBPs) are genotoxic, carcinogenic and mutagenic. Still chlorination is being practiced worldwide. Present review gives insights into the occurrence, toxicity and factors affecting the formation of regulated (THMs, HAAs) and emerging DBPs (N-DBPs, HKs, HAs and aromatic DBPs) found in drinking water. Furthermore, remediation techniques used to control DBPs have also been summarized here. Key findings are: (i) concentration of regulated DBPs surpassed the permissible limit in most of the regions, (ii) high chlorine dose, high NOM, more reaction time (up to 3 h) and high temperature (up to 30 °C) enhance the formation of THMs and HAAs, (iii) high pH favors the formation of THMs while low pH is suitable of the formation of HAAs, (iv) high NOM, low temperature, low chlorine dose and moderate pH favors the formation of unstable DBPs (N-DBPs, HKs and HAs), (v) DBPs are toxic not only for humans but for aquatic fauna as well, (vi) membrane technologies, enhanced coagulation and AOPs remove NOM, (vii) adsorption, air stripping and other physical and chemical methods are post-formation approaches (viii) step-wise chlorination is assumed to be an efficient method to reduce DBPs formation without any treatment. Toxicity data revealed that N-DBPs are found to be more toxic than C-DBPs and aromatic DBPs than aliphatic DBPs. In majority of the studies, merely THMs and HAAs have been studied and USEPA has regulated just these two groups. Future studies should focus on emerging DBPs and provide information regarding their regulation.

Effects of the tributyltin on the blood parameters, immune responses and thyroid hormone system in zebrafish

Tributyltin (TBT) is a widely used organotin compound around the world and was frequently detected in surface waters, which would pose risk to aquatic organisms. However, the mechanisms of TBT-induced toxicity is not full clear. The present study investigated the effects of the tributyltin (TBT) on the blood parameters, immune responses and thyroid hormone system in zebrafish. Fish were exposed to sublethal concentrations of TBT (10 ng/L, 100 ng/L and 300 ng/L) for 6 weeks. The effects of long-term exposure to TBT on blood parameters (NH3, ammonia; GLU, glucose; TP, total proteins; CK, creatine kinase; ALT, alanine aminotransferase; AST, aspartate aminotransferase), immune responses (Lys, lysozyme; IgM, immunoglobulin M) and some indexes related thyroid hormone system (T3, 3,5,3'-triiodothyronine; T4, thyroxine) were measured in zebrafish, as well as the expression of genes related to immune responses and thyroid hormone system. Based on the results, the physiological-biochemical responses was significantly enhanced with an increase in TBT concentration, reflected by the abnormal blood indices, dysregulation of endocrine system and immunotoxicity in zebrafish under TBT stress. The present study greatly extends our understanding of adverse effects of TBT on aquatic organisms.

High concentration and high dose of disinfectants and antibiotics used during the COVID-19 pandemic threaten human health

The issue of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), has created enormous threat to global health. In an effort to contain the spread of COVID-19, a huge amount of disinfectants and antibiotics have been utilized on public health. Accordingly, the concentration of disinfectants and antibiotics is increasing rapidly in various environments, including wastewater, surface waters, soils and sediments. The aims of this study were to analyze the potential ecological environment impacts of disinfectants and antibiotics by summarizing their utilization, environmental occurrence, distribution and toxicity. The paper highlights the promoting effects of disinfectants and antibiotics on antibiotic resistance genes (ARGs) and even antibiotic resistant bacteria (ARB). The scientific evidences indicate that the high concentration and high dose of disinfectants and antibiotics promote the evolution toward antimicrobial resistance through horizontal gene transformation and vertical gene transformation, which threaten human health. Further concerns should be focused more on the enrichment, bioaccumulation and biomagnification of disinfectants, antibiotics, antibiotic resistance genes (ARGs) and even antibiotic resistant bacteria (ARB) in human bodies.