Effects of surfactants on the combined toxicity of TiO_2 nanoparticles and cadmium to Escherichia coli

The combined ecological toxicity of TiO2 nanoparticles（nano-TiO2） and heavy metals has been paid more attention. As the common pollutants in water environment, surfactants could affect the properties of nanoparticles and heavy metals, and thus further influence the combined toxicity of nano-TiO2 and heavy metals. In this study, the effects of sodium dodecyl benzene sulfonate（SDBS） and Tween 80 on the single and combined toxicities of Cd2＋ and nano-TiO2 to Escherichia coli（E. coli） were examined, and the underlying influence mechanism was further discussed. The results showed both SDBS and Tween 80 enhanced the toxicity of Cd2＋ to E. coli in varying degrees. The reaction of SDBS and Cd2＋ could increase the outer membrane permeability and the bioavailability of Cd, while Tween 80 itself could enhance the outer membrane permeability. The combined toxicity of nano-TiO2 and Cd2＋ to E. coli in absence of surfactant was antagonistic because of the adsorption of Cd2＋ to nanoTiO2 particles. However, in the presence of SDBS, both SDBS and nano-TiO2 influenced the toxicity of Cd2＋ , and also SDBS could adsorb to nano-TiO2 by binding to Cd2＋ . The combined toxicity was reduced at Cd2＋ lower than 4 mg/L and enhanced at Cd2＋ higher than 4 mg/L under multiple interactions. Tween 80 enhanced the combined toxicity of nano-TiO2 and Cd2＋ by increasing the outer membrane permeability. Our study firstly elucidated the effects of surfactants on the combined toxicity of nano-TiO2 and Cd2＋ to bacteria, and the underlying influencing mechanism was proposed.

Estimating the combined toxicity of flufenacet and imazaquin to sorghum with pore water herbicide concentration

Combined toxicity of herbicides to non-target crops is usually resulted from their successive application.The present study was conducted to assess the combined toxicity of flufenacet（FLU）and imazaquin（IMA）to sorghum with their concentration in soil pore water.The concentrations that inhibited growth by 50%（IC50）of FLU and IMA individually and their combination estimated from the herbicide concentrations in soil pore water notably differed from those based on the amended concentrations,due to the decline in bioavailability resulting from adsorption of the herbicides onto soil.According to the amended concentrations,the combined effect of FLU and IMA in soil on sorghum growth was identified as additive action.Based on the concentration in soil pore water,however,it was determined to be antagonism,which was identical to that observed in a test using culture solution.The results revealed that pore water herbicide concentration might be an effective tool to assess the combined toxicity of herbicides in soil to rotational crops.

Combined Subchronic Toxicity of Bisphenol A and Dibutyl Phthalate on Male Rats

Objective To evaluate the combined subchronic toxicity of bisphenol A（BPA） and dibutyl phthalate（DBP） in male Sprague Dawley（SD） rats.Methods Forty 4‐week‐old male rats weighing 115‐125 g were randomly divided into BPA‐treated,DBP‐treated group,BPA＋DBP‐treated and control groups and fed with a soy‐ and alfalfa‐free diet containing 285.4 ppm BPA,285.4 ppm DBP,285.4 ppm BPA plus 285.4 ppm DBP,and a control diet,respectively,for 90 consecutive days.At the end of the study,the animals were sacrificed by exsanguination via the carotid artery under diethyl etherane aesthesia and weighed.Organs,including liver,kidneys,spleen,thymus,heart,brain,and testis underwent pathological examination.The androgen receptor（AR）,gonadotropin‐releasing hormone receptor（GNRHR）,and progesterone hormone receptor（PR） genes from the hypothalamus were detected by real‐time PCR.The biomedical parameters were analyzed.Results No significant difference was found in food intake,body weight,tissue weight,organ/brain weight ratio,and biomedical parameters among the four groups（P〉0.05）.However,BPA and DBP up‐regulated AR,PR and GNRHR expression levels in rats and showed a synergistic or an additive effect in the BPA＋DBP group.Conclusion The combined subchronic toxicity of BPA and DBP is synergistic or additive in male SD rats.

Photoinduced toxicity single and binary mixtures of four polycyclic aromatic hydrocarbons to the marine diatom Skeletonema costatum

Diatom Skeletonema costatum Cleve is one of the main predominant phytoplankton species in the Changjiang Estuary in China. In order to provide some basic information for future assessment of the potential risk on phytoplankton communities in this estuary caused by polycyclic aromatic hydrocarbons（ PAHs）, this alga was selected as a representative to investigate the photoinduced toxicity of PAHs, in single and mixture. Four PAHs including three-ring phenanthrene and anthracene, four-ring fluoranthene and pyrene were tested in the laboratory. The single toxicity of each PAH on this microalga was compared with and without the simulated solar UV radiation. The results showed that this microalga was sensitive to PAH＇ s photoinduced toxicity. Ratios of the 72 h median effect concentration obtained for fluorescent and UV light tests were about 8.4 for phenanthrene, 13.0 for anthracene, 6. 5 for fluoranthene, and 5.7 for pyrene, indicating that UV light enhanced the PAH toxicity to this alga significantly. Under the fluorescent radiation （lacking UV ）, the dose-response curves based on chemical concentrations revealed that the order of toxic strength was fluoranthene greater than pyrene greater than anthracene greater than phenanthrene; while under the UV radiation （476 μW/cm^2 for UVA, 6.5 μW/cm^2 for UVB） it became fluoranthene approximately equaling anthracene greater than pyrene greater than phenanthrene, indicating that the UV light also changed its relative toxicity to this alga. The photoinduced toxicity of PAHs to the marine diatom S. costatum might be a synergistic effect of photosensitization reactions （ e. g. , generation of singlestate oxygen） and photomodification （photooxidation and/or photolysis）. The combined effects of six binary mixtures on the marine diatom S. costatum were investigated using the additive-index method. Four binary-mixtures （ phenanthrene plus anthracene ; phenanthrene plus pyrene ; anthracene plus fluoranthene ; anthracene plus pyrene） were found to be synergistic joint action mode, while two binary-mixtures （phenanthrene plus fluoranthene; fluoranthene plus pyrene） displayed antagonist, revealing a complex pattern of possible interactions. The combined action mode of PAHs might be related to various factors such as the mixture compounds, mixture ratios and test conditions, etc.

Confirmation of combinational effects of calcium with other metals in a paper recycling mill effluent on nematode lifespan with toxicity identification evaluation method

We used toxicity identification evaluation （TIE） method to confirm the combinational effects of identified toxic metals in a paper recycling mill effluent in inducing the decreased lifespan in nematode Caenorhabditis elegans.Exposure to Ca ＋ Al caused more severely decreased lifespan than that exposed to Ca,or Al;and exposure to Ca ＋ Fe induced more severely decreased lifespan than that exposed to Ca,or Fe.Exposure to Ca＋Al＋Fe caused more severely decreased lifespan than that exposed to Ca,or Ca＋Fe.Moreover,the baseline toxicity on lifespan was doubled by doubling the concentration of combined metals （Ca＋Al＋Fe） in spiking test in original effluent （oe）,and lifespan defects in oe＋Ca＋Al＋Fe exposed nematodes were more severe than that in Ca＋Al＋Fe exposed nematode.Therefore,Ca＋Al＋Fe exposure may largely explain the formation of decreased lifespan induced by the examined industrial effluent.Furthermore,the observed reduction of lifespan induced by the combination of high level of Ca with other metals may be at least partially independent of the insulin-like pathway.

Renal Toxicity of Nickel,Sodium Lauryl Sulphate and Their Combination after Dermal Application in Guinea Pigs

The guinea pigs were dermally exposed to nickel (Ni), sodium lauryl sulphate (SLS) and in their combination for 7 and 14 days. The exposure to Ni and SLS produced changes in enzymes and lipid peroxidation in kidney. The exposure to Ni or SLS depicted slight changes while combined exposure to Ni plus SLS exhibited more degenerative changes in kidney. The result of the study suggests that industrial workers and/or populations exposed simultaneously to Ni and SLS produces more damage to kidney.

Combined effect of microplastic and triphenyltin:Insights from the gut-brain axis

Microplastics(MPs),an emerging group of pollutants,not only have direct toxic effects on aquatic organisms but also cause combined toxicity by absorbing other pollutants.Triphenyltin(TPT),one of the most widely used organotin compounds,has adverse effects on aquatic organisms.However,little is known about the combined toxicity of MPs and TPT to aquatic organisms.To investigate the individual and combined toxicity of MPs and TPT,we selected the common carp(Cyprinus carpio)for a 42-day exposure experiment.Based on the environmental concentrations in a heavily polluted area,the experimental concentrations of MPs and TPT were set at 0.5 mg L^(−1) and 1μg L^(−1),respectively.The effects of MPs combined with TPT on the carp gut-brain axis were evaluated by detecting gut physiology and biochemical parameters,gut microbial 16S rRNA,and brain transcriptome sequencing.Our results suggest that a single TPT caused lipid metabolism disorder and a single MP induced immunosuppression in carp.When MPs were combined with TPT,the involvement of TPT amplified the immunotoxic effect induced by MPs.In this study,we also explored the gut-brain axis relationship of carp immunosuppression,providing new insights for assessing the combined toxicity of MPs and TPT.At the same time,our study provides a theoretical basis for evaluating the coexistence risk of MPs and TPT in the aquatic environment.

Influences of Chloropazine, Nimodipine and Their Combination on the Toxic Effects of Cadmium in Liver and Kidney of Mice

The influences of the calmodulin antagonist chlorpromazine (CPZ), and calcium channel blocker nimodipine (NIMO) and their combination on cadmium (Cd) poisoning of mice were studied. A seties of biochemical parameters including urinary enzyme activities, blood and urine Cd levels, metallothionein (MT) contents in liver and kidney, hepatic ultrastructure and Ca2+ -Mg2+ AT-Pase activity in erythrocyte membrane were determined. Animal models for Cd poisoning were established by peritoneal injection of 1/5 LD50 CdCl2. The experimental groups were protected by administration of CPZ, NIMO and CPZ and NIMO in combination l h before the injection of CdCl2. Five days later, samples were collected for analysis. The data showed that Crs could protect kidney tissue against Cd-induced damage, as the urinary γ-glutamyl traspepti dase (γ- GT ) and N- acetyl-β-D-glucosaminidase (NAG) activities were reduced significantly. There was neither evidence of the protective effect of NIMO on kidney tissue nor an indication of a synergistic effecf of Crs and NIMO.Both CPZ and NIMO showed a considerable protective effect against the deerease in Ca2+ -Mg2+ AT-Pase activity, and a synergistic action was observed. Cd content in blood was reduced significanily by CPZ or the combination of CPZ and NIMO, but elevated by NIMO. Both CPZ and NIMO consideraby increased MT contents in livers and kidneys and ameliorated damaged to the hepatic ultrastructures caused by Cd. The results indicated that these inhibitors could protect mice against the toxic effects of Cd in liver and kidney tissues, while CPZ was more efficient than NIMO. The combination of CPZ and NIMO exerted a synergistic action. The protective action of these two drugs might be relevent to the function of MT.

Effect of Removing Toxic Substances Combined with Activating Blood Circulation on Stabilizing the Atherosclerotic Plaque and Unstable Angina

The therapeutic effects of activating blood circulation to remove stasis of Chinese medicine （CM） in the prevention and treatment of atherosclerotic diseases such as coronary artery disease and angina are generally acknowledged. In recent years, to further improve the therapeutic effects of those Chinese herbs on such diseases, we have carried out a series of studies of CM medications with the function of clearing heat and removing toxic substances combined with activating blood circulation to remove stasis.

Inductive and synergistic interactions between plant allelochemical flavone and Bt toxin Cry1 Ac in Helicoverpa armigera

Genetically engineered crops simultaneously produce defensive allelochemi-cals and Bacillus thuringiensis(Bt)toxin proteins to kill some of the world's most devastating insect pests.How the two types of toxins,when ingested sequentially or simultaneously,interact at both lethal and sublethal doses in these pests remains underexplored.Here,we examined the toxicological interactions between the Bt toxin Cry 1 Ac and the flavonoid allelochemical flavone in Helicoverpa armigera.Simultaneous exposure of H.armigera neonates to lethal doses(LC25)of Cry 1 Ac and flavone caused a mortality significantly higher than that of either toxin alone and their expected additive mortality.Preexposure for 24 h to a sublethal dose(LC10)of Cry 1 Ac followed by 6-d simultaneous exposure to the same dose of Cry 1 Ac plus a lethal dose(1.6 mg/g diets,LC50)of flavone resulted in a mortality significantly higher than that of the LC50 dose of flavone alone and the expected additive mortality of the LC50 dose of flavone plus the LC10 dose of Cry 1 Ac.One-day preexposure to the sublethal dose(LC10)of flavone followed by 6-d simultaneous exposure to the LC50 dose(6 ng/cm2)of Cry 1 Ac plus the LC25 dose of flavone yielded a mortality significantly higher than that of the LC50 dose of Cry 1 Ac but similar to the expected additive mortality of the LC50 dose of Cry 1 Ac plus the LC50 dose of flavone.The results suggest that Cry 1 Ac induces and synergizes the toxicity of flavone against H.armigera larvae.