Impact of changes in biofilm composition response following chlorine and chloramine disinfection on nitrogenous disinfection byproduct formation and toxicity risk in drinking water distribution systems.

In practical drinking water treatment, chlorine and chloramine disinfection exhibit different mechanisms that affect biofilm growth. This study focused on the influence of biofilm composition changes, especially extracellular polymeric substance (EPS) fractions, on the potential formation and toxicity of nitrogenous disinfection by-products (N-DBP). Significant differences in microbial diversity and community structure were observed between the chlorine and chloramine treatments. Notably, the biofilms from the chloramine-treated group had higher microbial dominance and greater accumulation of organic precursors, as evidenced by the semi-quantitative confocal laser-scanning microscopy assay of more concentrated microbial aggregates and polysaccharide proteins in the samples. Additionally, the chloramine-treated group compared with chlorine had a higher EPS matrix content, with a 13.5 % increase in protein. Furthermore, the protein distribution within the biofilm differed; in the chlorine group, proteins were concentrated in the central region, whereas in the chloramine group, proteins were primarily located at the water-biofilm interface. Notably, functional prediction analyses of protein fractions in biofilms revealed specific functional regulation patterns and increased metabolism-related abundance of proteins in the chlorine-treated group. This increase was particularly pronounced for proteins such as dehydrogenases, reductases, transcription factors, and acyl-CoA dehydrogenases. By combining the Fukui function and density functional calculations to further analyse the effect of biofilm component changes on N-DBP production under chlorine/chloramine and by assessing the toxicity risk potential of N-DBP, it was determined that chloramine disinfection is detrimental to biofilm control and the accumulation of protein precursors has a higher formation potential of N-DBPs and toxicity risk, increasing the health risk of drinking water.

Response mechanisms of pipe wall biofilms in water supply networks under different disinfection strategy pressures and the effect of mediating halogenated acetonitrile formation.

Residual chlorine and biofilm coexistence is inevitable in drinking water transmission and distribution networks. Understanding the microbial response and its mediated effects on disinfection byproducts under different categories of residual chlorine stress is essential to ensure water safety. The aim of our study was to determine the response of pipe wall biofilms to residual chlorine pressure in chlorine and chloramine systems and to understand the microbially mediated effects on the formation and migration of haloacetonitriles (HANs), typical nitrogenous disinfection byproducts. According to the experimental results, the biofilm response changes under pressure, with significant differences noted in morphological characteristics, the extracellular polymeric substances (EPS) spatial structure, bacterial diversity, and functional abundance potential. Upon incubation with residual chlorine (1.0 ± 0.2 mg/L), the biofilm biomass per unit area, EPS, community abundance, and diversity increased in the chloramine group, and the percentage of viable bacteria increased, potentially indicating that the chloramine group provides a richer variety of organic matter precursors. Compared with the chloramine group, the chlorination group exhibited increased haloacetonitrile formation potential (HANFP), with Rhodococcus (43.2%) dominating the system, whereas the prediction abundance of metabolic functions was advantageous, especially with regard to amino acid metabolism, carbohydrate metabolism, and the biodegradation and metabolism of foreign chemicals. Under chlorine stress, pipe wall biofilms play a stronger role in mediating HAN production. It is inferred that chlorine may stimulates microbial interactions, and more metabolites (e.g., EPS) consume chlorine to protect microbial survival. EPS dominates in biofilms, in which proteins exhibit greater HANFP than polysaccharides.

Polysaccharide extracted from cultivated Sanghuangporous vaninii spores using three-phase partitioning with enzyme/ultrasound pretreatment: Physicochemical characteristics and its biological activity in vitro.

Sanghuangporous vaninii, as a valuable dietary supplement and medicinal ingredient, contains abundant bioactive polysaccharides that have health-promoting effects. In the present study, four polysaccharides (SVSPs-C, SVSPs-E, SVSPs-U, and SVSPs-E/U) were extracted for the first time from S. vaninii spores by three-phase partitioning (TPP), enzyme pretreatment before TPP (E-TPP), ultrasonic pretreatment before TPP (U-TPP), and enzyme pretreatment followed by ultrasonic before TPP (E/U-TPP) methods, respectively. Their physicochemical characteristics and in vitro pharmacological functions were determined and compared. Results showed that four TPP-based extraction methods had remarkable impacts on the extraction yield, chemical properties, monosaccharide compositions, and molecular weights (Mw) of SVSPs. Specifically, SVSPs-E/U obtained by E/U-TPP showed the highest extraction yield (25.40 %), carbohydrate content (88.50 %), and the lowest protein content (0.86 %). The four SVSPs had high-Mw (183.8-329.1 kDa) and low-Mw (23.0-156.4 kDa) fractions and mainly consisted of galactose, glucose, and mannose with different contents. In vitro bioactivities assays indicated that SVSPs-E/U possessed stronger antioxidant, hypoglycemic, hypouricemic, immunostimulatory, and antitumor activities than those of SVSPs-C, SVSPs-E, and SVSPs-U. Therefore, our results provide an efficient and promising extraction technique for bioactive polysaccharides from S. vaninii spores, as well as SVSPs had the potential to be applied in functional food, pharmaceutical, and cosmetics fields.

Characterization of young biofilm morphology, disinfection byproduct formation potential and toxicity of renewed water supply pipelines by phosphorus release from corroded pipes.

The deterioration of drinking water quality due to corrosion of the water supply network has become inevitable and regular renewal of pipes has become a common means of doing so. Severely corroded pipes release certain nutrients (e.g., elemental phosphorus), however, little has been reported on the effect of old pipes on the young biofilm of new pipe sections and on ensuring water safety in the early stages of the water supply. The aim of our study was to model the effect of key phosphorus nutrients released from corroded old pipes on the morphological characteristics of young biofilms in new pipe sections, mediated disinfection byproducts (DBPs) production and their combined toxicity. Based on the experimental results, phosphorus showed significant differences in the morphological characteristics, spatial structure of extracellular polymers (EPS), functional abundance, disinfection byproduct formation potential (DBPsFP) and toxicity of young biofilms. Under residual chlorine (1.0 ± 0.2 mg/L) incubation, the functional abundance of young biofilm metabolism was dominant, particularly amino acid metabolism and carbohydrate metabolism. There is a dynamic balance between the trophic and shedding effects of phosphorus, where concentration changes affect young biofilm morphology and DBPFP. Relatively moderate phosphorus concentrations resulted in the highest density of PN/PS organic precursors in EPS and a clear advantage of DBPFP; relatively high phosphorus conditions had limited promotion of young biofilm, while membrane structure shedding was more pronounced, increasing young biofilm-mediated DBPs production. Nitrogen-containing disinfection byproducts (N-DBPs) in young biofilms had a clear toxicity advantage, with HANs and HNMs being key to controlling cytotoxicity and genotoxicity, respectively.

New methods based on a genetic algorithm back propagation (GABP) neural network and general regression neural network (GRNN) for predicting the occurrence of trihalomethanes in tap water.

Monitoring trihalomethanes (THMs) levels in water supply systems is of great significance in ensuring drinking water safety. However, THMs detection is a time-consuming task. Developing predictive THMs models using parameters that are easier to obtain is an alternative. To date, there is still no application of optimization algorithms and general regression neural networks in predicting disinfection by-products levels. This study was to explore the feasibility of back propagation neural network (BPNN), genetic algorithm back propagation (GABP) neural network and general regression neural network (GRNN) for predicting THMs occurrence in real water supply systems. The results showed that the BPNN models' prediction ability was limited (test rp = 0.571-0.857, N25 = 61.5 %-91.5 %). Optimized by the genetic algorithm (GA), GABP models were generated and exhibited better prediction performance (test rp = 0.573 and 0.696-0.863, N25 = 68.2 %-93.6 %). However, GABP models took a lot of time and their prediction performance was unstable. A GRNN was then used to generate simpler neural network models, and the resulting prediction performance was excellent (total trihalomethanes and bromodichloromethane: test rp = 0.657-0.824, N25 = 81.8 %-100 %). In general, GRNN was the best at predicting THMs concentrations among the three models. However, it is worth noting that the prediction accuracy of bromodichloromethane (BDCM) was not high, which may be due to the absence of key parameters affecting BDCM formation. Accurate predictions of THMs by GRNN with these nine water parameters made THMs monitoring in real water supply systems possible and practical.

Impact of biological activated carbon filtration and backwashing on the behaviour of PFASs in drinking water treatment plants.

PFASs are present in surface water, tap water and even commercial drinking water and pose a risk to human health. In this study, the treatment efficiency of 14 PFASs was studied in a large drinking water treatment plant (DWTP) using Taihu Lake as the source, and it was found that the ozone/biological activated carbon (O3-BAC) process was the most effective process for the removal of PFASs in DWTPs. For the O3-BAC process, there were differences in the removal of PFASs by BACs (1,4,7,13 years) of different ages. The sterilization experiments revealed that for GAC, its physical adsorption capacity reached saturation after one year, while for BAC with mature biofilms, biosorption was the main mechanism for the removal of PFASs. The abundance of Alphaproteobacteria and Gammaproteobacteria in biofilms was positively correlated with the age of the BAC. The microbial community with higher abundance is beneficial to the biodegradation of organic matter and thus provides more active sites for the adsorption of PFASs. PFASs can leak in the early stage of filtration after backwashing, so it is necessary to pay close attention to the influent and effluent concentrations of PFASs during biofilm maturation after backwashing.

Recent advances in the bioactive polysaccharides and other key components from Phellinus spp. and their pharmacological effects: A review.

Phellinus spp. is one of the largest genera of Hymenochaetaceae with approximately 220 species, such as P. vaninii, P. buamii, P. linteus, and P. igniarius, these species are considered as precious food supplements and medicinal ingredients in China, Korea, Japan, and other Asian countries for over 2000 years. Phellinus spp. contains abundant bioactive polysaccharides and other key components (e.g., phenolics, terpenes, steroids, etc.). Pharmacological investigations have confirmed that bioactive polysaccharides and other important secondary metabolites from Phellinus spp. possess multiple health-promoting benefits, including antitumor, immunomodulatory, anti-inflammatory, antidiabetic, antioxidant, and antimicrobial effects. However, comprehensive evaluations on the preparation and structural characteristics, bioactivities, and toxicology of these functional components (e.g., polysaccharides, phenolics, terpenes, steroids) from various Phellinus spp. species are very limited, which may restrict the practical application of Phellinus spp. This review summarizes the physicochemical characteristics, pharmacological activities, and possible mechanisms of bioactive components from Phellinus spp. according to published studies from 2017 to 2022. It also surveyed the toxicological assessment for safety and applications of different Phellinus spp. species. This review aims to provide useful references and promising directions for the comprehensive development and utilization of Phellinus spp. in functional foods, pharmaceuticals, and cosmetics.

Adsorption of perfluoroalkyl acids on granular activated carbon supported chitosan: Role of nanobubbles.

The safety threat posed by Perfluoroalkyl acids (PFAAs) in drinking water is a growing concern. In this study, we loaded chitosan (CS) on granular activated carbon (GAC) to adsorb PFAAs, and we explored the role of nanobubbles in the adsorption process through experiments and density functional theory (DFT) calculations. Compared with GAC, we found that the use of the composite adsorbent (CS/GAC) enhanced the removal rate of perfluorooctanoic acid by 136% with the assistance of nanobubbles. PFAAs with different chain lengths have different adsorption mechanisms owing to surface activity differences. PFAAs with longer C-F chains can be directly enriched with amino groups on the CS or air-water interface on composite adsorbents. Additionally, PFAAs can be enriched with nanobubbles in solution to form nanobubble-PFAA colloids, which are adsorbed by protonated amino groups on CS through electrostatic interactions. We found that PFAAs with shorter C-F chains are less affected by nanobubbles, and DFT calculations indicated that the adsorption of short-chain PFAAs is mainly affected by electrostatic interactions. We also proved that the electrostatic interactions between CS and PFAAs are mainly derived from the abundant protonated amino groups.

Treatment of bromate in UV/sulfite autoxidation process enhances formation of dibromoacetonitrile during chlorination.

The integration of UV/sulfite autoxidation process (USAP, i.e., UV activation of sulfite in the presence of 5 ∼ 10 mg/L O2) into conventional water to degrade micropollutants rises extensive attention, but its impact on water quality, and especially the formation of disinfection byproducts is still unclear. Herein, the formation of dibromoacetonitrile (DBAN) from bromate (BrO3-) upon treatment with USAP followed by chlorination was evaluated, in the presence of amino acids (AAs) selected as representative organic matter in drinking water. Results revealed that hydrated electrons (eaq-) produced during USAP contribute to the reduction of BrO3- to Br-, which is then converted into HBrO/BrO- during post-chlorination. At the same time, sulfate radicals (SO4•-) and hydroxyl radicals (•OH) generated in USAP mediated AAs' conversion via α-hydrogen abstraction and NH2-hydrogen abstraction reactions to produce HN=C(CH3)‒COOH, CH3‒CH=NH, and CH3‒CN, which are released into the post-chlorination stage and therefore, enhance the bromine utilization factor (BUF) value and DBAN formation. The effects of the USAP treatment time, BrO3- concentration, AA concentration, pH, and real waters were also evaluated. Although 63.5% of BrO3- was eliminated by USAP followed by chlorination, the toxicity index (TI) was increased by 1.5-fold due to the formation of the all brominated CX3R-type nitrogenous disinfection byproducts (N-DBPs), demonstrating the potential risk of applying USAP as a treatment process in BrO3- containing waters.

Modulatory effects of polysaccharides from plants, marine algae and edible mushrooms on gut microbiota and related health benefits: A review.

Naturally occurring carbohydrate polymers containing non-starch polysaccharides (NPs) are a class of biomacromolecules isolated from plants, marine algae, and edible mushrooms, and their biological activities has shown potential uses in the prevention and treatment of human diseases. Importantly, NPs serve as prebiotics to provide health benefits to the host through stimulating the proliferation of beneficial gut microbiota (GM) and enhancing the production of short-chain fatty acids (SCFAs). The composition and diversity of GM play a critical role in regulating host health and have been extensively studied in recent years. In this review, the extraction, isolation, purification, and structural characterization of NPs derived from plants, marine algae, and edible mushrooms are outlined. Importantly, the degradation and metabolism of these NPs in the intestinal tract, the effects of NPs on the microbial community and SCFAs generation, and the beneficial effects of NPs on host health by modulating GM are systematically highlighted. Overall, we hope that this review can provide some theoretical references and a new perspective for applications of NPs as prebiotics in functional food and drug development.

Impact of pipe material and chlorination on the biofilm structure and microbial communities.

Pipe material and residual chlorine are key factors for the drinking water distribution system, and understanding the biofilm ecosystem is vital for water quality safeguard. The aim of our study was to determine the influence of pipe materials (ductile iron, steel, polyethylene) and chlorination on the biofilm structure and microbial community, as shown by the physicochemical properties, extracellular polymeric substances (EPS) structural characteristics, bacterial community composition, and functional traits. EPS spatial properties were studied based on a semi-quantitative confocal laser scanning microscope (CLSM) description. Regarding the impact of chlorination, residule chlorine (1.0 ± 0.3 mg L-1 free chlorine) could inhibit the bacteria colonization, and initiate a potential response to external disinfectants revealed by the EPS spatial distribution changes and communities variation compared to unchlorinated system. Regarding the impact of pipe material, polyethylene (PE) biofilms displayed lower biomass, loose zoogloea structure, lower proteins and polysaccharides content, and poor microbial diversity in contrast to ductile iron and steel biofilms. Pipe material was the more possible driving factor of the biofilm community composition compared to the chlorination based on principal coordinates analysis (PCoA) and permutational multivariate analysis of variance (PERMANOVA). Actinobacteria was dominant in the PE biofilms (45.57%-83.32%), while Alphaproteobacteria (34.30%-73.22%) and Gammaproteobacteria (6.46%-36.82%) were the major classes in the steel and ductile iron biofilms. The genus Rhodococcus was predominant in the PE biofilms. Rhodococcus, Pseudomonas, and Sphingomonas seemed to have a better growth advantage in the chlorinated system and display a stronger disinfectant resistance. Functional sketch prediction indicated the potential impact of pipe material and chlorination on functional pathway abundnce, possible functional pathways associated with infectious disease included. This study provides insights into the impact of pipe material and chlorination on biofilm structure and microbial community and might help to develop monitoring or maintenance strategies to protect the biosafety of the drinking water.

Electrochemically Quantifying the Phase Transition of Cesium Lead Halide Perovskite Quantum Dots in Purification.

A good purification strategy for obtaining high-quality and low-cost perovskite QDs ink requires a complete removal of the impurities but with a minimal phase transition of QDs from the perovskite phases to the nonperovskite δ-phase. This pioneering work reports the electrochemical quantification on the phase transition level of CsPbI3 QDs in purification. Cyclic voltammetry of the purified QDs evidenced the formation of a new product in the purification process, which was demonstrated to be the undesired nonperovskite δ-phase by independent structural analysis. The developed electrochemical methodology further enabled the quantification of the extent of the phase transition of the QDs purified using different strategies by simply analyzing the charge associated with the relevant peaks and allowing optimization of the purification. The latter is of vital importance for commercialization and is an essential step for boosting their device performance.

Antioxidant and Neuroprotector Influence of Endo-Polyphenol Extract from Magnesium Acetate Multi-Stage Addition in the Oak Bracket Medicinal Mushroom, Phellinus baumii (Agaricomycetes).

The objective of this study was to explore the effect of magnesium acetate (MA) addition on the endo-polyphenol yield by Phellinus baumii and establish a feasible additive strategy. The optimal three-point MA addition strategy (0.05 g/L concentration of MA added at 0 h and 6 h, 0.9 g/L concentration of MA added at 12 h) was employed to obtain maximum endo-polyphenol yield. The maximum endo-polyphenol production was reached at 1.22 g/L, which was 1.39-fold higher than that of the control. Additionally, the endo-polyphenol showed stronger antioxidant activity in vitro compared with the control, including DPPH· scavenging capacity (78.76%) and Trolox equivalent antioxidant capacity (TEAC) (32.28 µmol Trolox/g sample). HPLC analysis showed that the endo-polyphenol production of the crude ethanol extracts was significantly higher than that of the control. Hispidin was isolated and identified from the ethanol extract of the culture mycelia from Ph. baumii with the three-point MA addition strategy. Hispidin showed a strong ability to scavenge DPPH free radicals and TEAC, equivalent to positive (vitamin C) value of 89.41% and 75.98%, respectively. Furthermore, hispidin protected H2O2-induced PC12 cells injured by decreased oxidative stress level. These results indicated that the MA multi-stage addition strategy was dependable, and could be used to develop new natural antioxidants for foods or medicines.

Breviscapine suppresses the growth and metastasis of prostate cancer through regulating PAQR4-mediated PI3K/Akt pathway.

OBJECTIVES: Prostate cancer, one of the most frequently diagnosed tumors of men, leads to poor quality of life. Previous studies have shown that breviscapine (BRE) exerts therapeutic activity in malignant tumors. However, the role and mechanism of BRE exhibit an anti-tumor effect on prostate cancer are largely unknown. METHODS: The mRNA and protein levels in prostate cancer tissues and cell lines were measured using RT-qPCR, western blot, and immunohistochemical staining, respectively. Cell proliferation, invasion, and migration in both PC3 and DU145 cells were evaluated using CCK-8 and Transwell assay. The effect of BRE on cell proliferation and metastasis by regulating the PAQR4-mediated PI3K/Akt pathway in vitro and in vivo was determined. RESULTS: PAQR4 was significantly overexpressed in prostate cancer tissues and cell lines, which was positively correlated with poor prognosis. Knockdown of PAQR4 inhibited the proliferation, invasion, migration, and epithelial-mesenchymal transition (EMT) of both PC3 and DU145 cells. Mechanistically, BRE treatment significantly suppressed the malignant biological behavior of both prostate cancer cells by downregulating PAQR4 and blocking the PI3K/Akt pathway. In vivo experiments, BRE administration remarkably inhibited tumor growth and metastasis in a xenograft model of prostate cancer. CONCLUSION: Our findings revealed that BRE exerts anti-tumor and anti-metastasis roles in prostate cancer by inhibiting PAQR4-mediated PI3K/Akt pathway, which provides a new therapeutic agent for prostate cancer clinical treatment.

Employment of ARTP to Generate Phellinus baumii (Agaricomycetes) Strain with High Flavonoids Production and Validation by Liquid Fermentation.

To obtain Phellinus baumii strain with high flavonoids yield, ARTP was employed to generate mutants of a Ph. baumii strain, which were screened for higher flavonoids content. After five rounds of screening, four mutants were identified to produce more flavonoids than the wild type strain under optimal conditions, of which A67 was the mutant with the highest flavonoids productive capacity. When cultured in shake flasks, the maximum intracellular total flavonoids production of A67 reached 0.56 g/L, 86.67% higher than the total flavonoids in CK. Antagonistic testing, RAPD, and HPLC analysis suggested that ARTP caused changes of the genetic material and metabolites in Ph. baumii. In addition, the superiority of A67 to CK was proved by liquid fermentation using unstructured kinetic models, which was performed in a 50-L fermentor. The maximum intracellular total flavonoids production and dry mycelium weight of A67 reached 0.64 g/L and 15.24 g/L, which was an increase of 88.24% and 18.23% compared with CK, respectively. This work could provide an efficient and practical strategy to obtain high flavonoids production strains and the superiority of A67 could also provide a reference to further increase flavonoids production of Ph. baumii in large-scale production mode by submerged fermentation process.

Kinetic models for the effect of temperature on flavonoid production in liquid submerged fermentation by Phellinus baumii.

Kinetic models and temperature control strategy were established to reflect the effect of temperature (22 °C-30 °C) on flavonoid production of Phellinus baumii (P. baumii) in 6-L fermentor. A modified Logistic equation, Hinshelwood model, and Luedeking Piret equation were used to describe mycelial growth and product formation. The influence of temperature on the estimated kinetic parameters was further studied by regression analysis. Based on kinetic parameters analysis, the new temperature control strategy was proposed. Briefly, at 0-43 H, decreasing temperature (30 °C-28 °C) can shorten the lag phase of mycelial growth, and at 43-90 H, fermentation temperature was reduced gradually from 28 °C to 24 °C to keep high flavonoid productivity. At the fermentation anaphase (90-161 H), temperature was controlled at 24 °C to relieve inhibition of flavonoid and maintain constant production capacity of flavonoid. As a result, the maximum flavonoid yield was reached 4.21 mg/100 mg cell dry weight by temperature control strategy, which was 70.45% higher than that at a constant temperature of 26 °C. Additionally, the establishment of kinetic models based on fermentation temperature, which presented here may provide a scientific basis for further large scales flavonoid production of P. baumii in submerged fermentation.

The shadow of dichloroacetonitrile (DCAN), a typical nitrogenous disinfection by-product (N-DBP), in the waterworks and its backwash water reuse.

Dichloroacetonitrile (DCAN) is one of nitrogenous disinfection by-products (N-DBPs) with strong cytotoxicity and genotoxicity. In this study, the formation potential (FP) of DCAN was investigated in the samples of six important water sources located in the Yangtze River Delta. The highest formation concentration of DCAN was 9.05 µg/L in the water sample taken from Taihu Lake with the lowest SUVA value. After the NOM fractionation, the conversion rate of hydrophilic fraction to DCAN was found the highest. Subsequently, a waterworks using Taihu Lake as water source was chosen to research the FP variations of DCAN in the treatment process and backwash water. The results showed that, compared to the conventional treatment process, O/biological activated carbon (BAC) process increased the removal efficiency of DCAN from 21.89% to 50.58% by removing aromatic protein and soluble biological by-products as main precursors of DCAN. The DCAN FP in the effluent of BAC filters using old granular activated carbon was higher than that in the influent and the DCAN FP of its backwash water was lower than that in raw water. In the backwash water of sand filters, the DCAN FP higher than raw water required the recycle ratio less than 5% to avoid the accumulation of DCAN.

Acute toxicity of dichloroacetonitrile (DCAN), a typical nitrogenous disinfection by-product (N-DBP), on zebrafish (Danio rerio).

Dichloroacetonitrile (DCAN) is a typical nitrogenous disinfection by-product (N-DBP) and its toxicity on aquatic animals is investigated for the first time. The present study was designed to investigate the potential adverse effects of DCAN on zebrafish. DCAN could induce developmental toxicity to zebrafish embryos. A significant decrease in hatchability and an increase in malformation and mortality occurred when DCAN concentration was above 100µg/L. Heart function alteration and neuronal function disturbance occurred at concentration higher than 500 and 100µg/L, respectively. Further, DCAN was easily accumulated in adult zebrafish. The rank order of declining bioconcentration factor (BCF) was liver (1240-1670)> gill (1210-1430)> muscle (644-877). DCAN caused acute metabolism damage to adult zebrafish especially at 8 days exposure, at which time the "Integrated Biomarker Response" (IBR) index value reached 798 at 1mg/L DCAN dose. Acute DNA damage was induced to adult zebrafish by DCAN even at 10µg/L dose.