Non-targeted analysis based on quantitative prediction and toxicity assessment for emerging contaminants in tire particle leachates.

Non-targeted analysis (NTA) has great potential to screen emerging contaminants in the environment, and some studies have conducted in-depth investigation on environmental samples. Here, we used a NTA workflow to identify emerging contaminants in used tire particle (TP) leachates, followed by quantitative prediction and toxicity assessment based on hazard scores. Tire particles were obtained from four different types of automobiles, representing the most common tires during daily transportation. With the instrumental analysis of TP leachates, a total of 244 positive and 104 negative molecular features were extracted from the mass data. After filtering by a specialized emerging contaminants list and matching by spectral databases, a total of 51 molecular features were tentatively identified as contaminants, including benzothiazole, hexaethylene glycol, 2-hydroxybenzaldehyde, etc. Given that these contaminants have different mass spectral responses in the mass spectrometry, models for predicting the response of contaminants were constructed based on machine learning algorithms, in this case random forest and artificial neural networks. After five-fold cross-validation, the random forest algorithm model had better prediction performance (MAECV = 0.12, Q2 = 0.90), and thus it was chosen to predict the contaminant concentrations. The prediction results showed that the contaminant at the highest concentration was benzothiazole, with 4,875 µg/L in the winter tire sample. In addition, the joint toxicity assessment of four types of tires was conducted in this study. According to different hazard levels, hazard scores increasing by a factor 10 were developed, and hazard scores of all the contaminants identified in each TP leachate were summed to obtain the total hazard score. All four tires were calculated to have relatively high risks, with winter tires having the highest total hazard score of 40,751. This study extended the application of NTA research and led to the direction of subsequent targeting studies on highly concentrated and toxic contaminants.

A review of tire wear particles: Occurrence, adverse effects, and control strategies.

Tire wear particles (TWPs), common mixed particulate emerging contaminants in the environment, have global per capita emissions accounting for 0.23-1.9 kg/year, attracting global attention recently due to their wide detection, small size, mobility, and high toxicity. This review focuses on the occurrence characteristics of TWPs in multiple environmental media, adverse effects on organisms, potential toxicity mechanisms, and environmental risk prevention and control strategies of TWPs. The environmental fate of TWPs throughout the entire process is systematically investigated by the bibliometric analysis function of CiteSpace. This review supplements the gap in the joint toxicity and related toxicity mechanisms of TWPs with other environmental pollutants. Based on the risks review of TWPs and their additives, adverse impacts have been found in organisms from aquatic environments, soil, and humans, such as the growth inhibition effect on Chironomus dilutes. A multi-faceted and rationalized prevention and control treatment of "source-process-end" for the whole process can be achieved by regulating the use of studded tires, improving the tire additive formula, growing plants roadside, encouraging micro-degradation, and other methods, which are first reviewed. By addressing the current knowledge gaps and exploring prospects, this study contributes to developing strategies for reducing risks and assessing the fate of TWPs in multiple environmental media.

The adsorption and its mechanism of venlafaxine by original and aged polypropylene microplastic and the changes of joint toxicity.

Conjugation with the increment of consumption of polypropylene (PP) masks and antidepressants during pandemic, PP microplastics (MPs) and Venlafaxine (VEN) widely co-existed in surface waters. However, their environmental fate and the combined toxicity were unclear. Hence, we investigated the adsorption behaviors, and associated mechanisms of PP MPs for VEN. The impact factors including pH, salinity, and MPs aging were estimated. The results indicated PP MPs could adsorb amount of VEN within 24 h. The pseudo second-order kinetic model (R2 = 0.97) and Dubinin-Radushkevich model (R2 = 0.89) fitted well with the adsorption capacity of PP MPs for VEN, implying that chemical adsorption accompanied by electrostatic interaction might be the predominant mode for the interactions between PP MPs and VEN. Meanwhile, the adsorption capacity of PP MPs declined from pH of 2.5-4.5 and then increased from 4.5 to 9.5. The increased salinity (5-35 ppt) significantly suppressed the adsorption capacity. Aging by sunlight and UV triggered the formation of new functional group (carbonyl) on MPs, and then enhanced the adsorption capacity for VEN. Gaussian Model analysis further evidenced the electrostatic adsorption occurring in PP MPs and VEN. The combined exposure to PP MPs and VEN showed significantly antagonistic toxicity on Daphnia magna. The adsorption of VEN by PP MPs mitigated the lethal effects and behavioral function impairment posed by VEN on animals, implying the potential protective effects on zooplankton by PP MPs. This study for the first time provides perspective for assessing the environmental fate of MPs and antidepressants in aquatic system.

Enhanced biotoxicity by co-exposure of aged polystyrene and ciprofloxacin: the adsorption and its influence factors.

Microplastics (MPs), as emerging contaminants, usually experience aging processes in natural environments and further affect their interactions with coexisted contaminants, resulting in unpredictable ecological risks. Herein, the effect of MPs aging on their adsorption for coexisting antibiotics and their joint biotoxicity have been investigated. Results showed that the adsorption capacity of aged polystyrene (PS, 100 d and 50 d) for ciprofloxacin (CIP) was 1.10-4.09 times higher than virgin PS due to the larger BET surface area and increased oxygen-containing functional groups of aged PS. Following the increased adsorption capacity of aged PS, the joint toxicity of aged PS and CIP to Shewanella Oneidensis MR-1 (MR-1) was 1.03-1.34 times higher than virgin PS and CIP. Combined with the adsorption process, CIP posed higher toxicity to MR-1 compared to aged PS due to the rapid adsorption of aged PS for CIP in the first 12 h. After that, the adsorption process tended to be gentle and hence the joint toxicity to MR-1 was gradually dominated by aged PS. A similar transformation between the adsorption rate and the joint toxicity of PS and CIP was observed under different conditions. This study supplied a novel perception of the synergistic effects of PS aging and CIP on ecological health.

Individual and joint effects of glyphosate and cypermethrin formulations on two human cell lines.

The final effect of pesticides and their mixtures on living organisms is determined by the particular toxicodynamics of the system. Oxidative stress is one of the most studied molecular mechanisms of toxicity due to increasing evidence supporting its association with the toxic effects of different agrochemicals. In the present study we evaluated the presence of redox balance alterations in the cell lines HEp-2 and A549 exposed to formulations of glyphosate (March®) and cypermethrin (Superfina®) used separately or in combination (in a proportion equivalent to that used in soybean fields). We determined the activity of catalase, superoxide dismutase, glutathione S-transferase, intracellular GSH content, content of oxidized proteins (as measure of damage) and intracellular ROS content in both cell lines at two different mixture concentrations. Additionally, we evaluated the presence of statistical interaction to determine if the effect of the mixture on the parameters evaluated was additive, synergistic, or antagonistic. For this purpose, we used the Combination Subthresholding, Cooperative Effect and Statistical Linear Interaction approaches. We found that the interaction between pesticides depended on their concentration and the cellular models studied.

Joint toxicity of insecticides against Hyalomma asiaticum.

Hyalomma asiaticum, a hematophagous ectoparasite, causes severe economic losses. We studied the acute toxicity of five pesticides (three single-agent and two combination preparations) to this organism. Engorged larval ticks were immersed in ten serial concentrations of each insecticide and observed for 20 days. The LC50 values of the five insecticides and the cotoxicity coefficients (CTCs) of the two mixtures were estimated for H. asiaticum. The CTCs of lambda-cyhalothrin + etoxazole and lambda-cyhalothrin + fipronil were 128.83 and 331.58, respectively, each demonstrating synergism. The results indicated that these two mixtures were more effective than individual insecticides, and this study suggests a substitutional approach to the control of ticks.

Toxicity of benzethonium chloride and polyhexamethylene guanidine hydrochloride mixtures on Daphnia carinata: synergistic and antagonistic effects at specific ratios.

Throughout the coronavirus (COVID-19) pandemic, the sanitizing products benzethonium chloride (BEC) and polyhexamethylene guanidine hydrochloride (PHMG-H) were widely used; however, few studies have investigated their combined toxicity to organisms. In the present study, acute toxicity and genotoxicity of BEC, PHMG-H, and the combination of the two were investigated as endpoints using Daphnia carinata as the model organism. For individual reagents, PHMG-H was found to be more toxic than BEC in terms of both mortality and genotoxicity. DNA damage and survival rate were used as toxicity endpoints. The interaction was evaluated with the concentration addition (CA) model via toxic unit (TU) approach and additive index (AI) method in mixtures at different ratios in TU. Only the binary mixture BEC + PHMG-H at the ratio 1:9 in TU was regarded as synergistic, while all others indicated increased antagonistic effects as the proportion of BEC increased over the PHMG-H concentration. The findings here benefit understanding surrounding precisely how BEC and PHMG-H interact at different mixing ratios, and can assist with the evaluation of risk assessments for binary mixtures in aquatic ecosystems.

The toxicological effect on pak choi of co-exposure to degradable and non-degradable microplastics with oxytetracycline in the soil.

Microplastics and antibiotics are emerging as ubiquitous contaminants in farmland soil, harming crop quality and yield, and thus threatening global food security and human health. However, few studies have examined the individual and joint effects of degradable and/or non-degradable microplastics and antibiotics on crop plants. This study examined the individual and joint effects of polyethylene (PE) and polylactic acid (PLA) microplastics and the antibiotic oxytetracycline (OTC) on pak choi by measuring its growth, photosynthesis, antioxidant enzyme activity, and metabolite levels. Microplastics and/or oxytetracycline adversely affected root weight, photosynthesis, and antioxidant enzyme (superoxide dismutase, catalase, and ascorbate peroxidase) activities. The levels of leaf metabolites were significantly altered, causing physiological changes. Biosynthesis of plant secondary metabolites and amino acids was altered, and plant hormones pathways were disrupted. Separately and together, OTC, PE, and PLA exerted phytotoxic and antagonistic effects on pak choi. Separately and together with OTC, degradable microplastics altered the soil properties, thus causing more severe impacts on plant performance than non-degradable microplastics. This study elucidates the effects on crop plants of toxicity caused by co-exposure to degradable or non-degradable microplastic and antibiotics contamination and suggests mechanisms.

Assessment of Joint Toxicity of Arsenate and Lead by Multiple Endpoints in Chlamydomonas reinhardtii.

In aquatic ecosystems, arsenate (As(V)) and lead (Pb(II)) frequently coexist but their joint toxicity on microalgae remains unknown. In this study, Chlamydomonas reinhardtii was exposed to various levels of combined As(V) and Pb(II) treatments. The cell growth, respiration, pigment synthesis, polysaccharides and protein secretion as well as As speciation of C. reinhardtii were analyzed. The low-level coexistence of As(V) and Pb(II) had a stimulatory effect, as indicated by enhanced cell proliferation. In the middle-level coexistence, the cells resisted the toxicity by significant increasing protein secretion. Under high-level coexistence, the presence of Pb(II) inhibited the efflux of As and caused the decline of cell numbers and occurrence of cell lysis, indicating that the interaction mode between As(V) and Pb(II) switched to synergistic. Taken together, the above findings may deepen the understanding of detoxification mechanisms of algae upon exposure to combined metal(loid)s in aqueous environments.

Aged microplastics enhance their interaction with ciprofloxacin and joint toxicity on Escherichia coli.

Microplastics (MPs) in natural environments undergo complex aging processes, changing their interactions with coexisting antibiotics, and posing unpredictable ecological risks. However, the joint toxicity of aged MPs (aMPs) and antibiotics to bacteria, especially at the molecular level, is unclear. In this study, non-thermal plasma technology was used to simultaneously simulate various radical oxidation and physical reactions that occur naturally in the environment, breaking the limitation of simple aging process in laboratory aging technologies. After aging, we investigated the altered properties of aMPs, their interactions with ciprofloxacin (CIP), and the molecular responses of E. coli exposed to pristine MPs (13.5 mg/L), aMPs (13.5 mg/L), and CIP (2 µg/L) individually or simultaneously. aMPs bound far more CIP to their surfaces than pristine MPs, especially in freshwater ecosystems. Notably, the growth of E. coli exposed to aMPs alone was inhibited, whereas pristine MPs exposure didn't affect the growth of E. coli. Moreover, the most differentially expressed genes in E. coli were induced by the coexposure of aMPs and CIP. Although E. coli depended on chemotaxis to improve its flagellar rotation and escaped the stress of pollutants, the coexposure of aMPs and CIP still caused cell membrane damage, oxidative stress, obstruction of DNA replication, and osmotic imbalance in E. coli. This study filled the knowledge gap between the toxicity of aMPs and pristine MPs coexisting with antibiotics at the transcription level, helping in the accurate assessment of the potential risks of MPs to the environment.

The Joint Toxicity of Organic Three-dimensional Layered Double Hydroxide and Methyl Orange to Green Algae Chlorella Vulgaris.

Organic modified layered double hydroxides (O-LDHs), known as attractive adsorbents for organic pollutants, may pose severe toxicity to the aquatic organisms during their large-scale application. However, little information is available on the toxicity of O-LDHs and the joint toxicity with the coexisted organic pollutants. Herein, we employed organic three-dimensional layered double hydroxide (O3D-LDH) and methyl orange (MO) as representative to investigate the toxicity mechanisms of single substance and its binary mixture on green algae Chlorella vulgaris. Results showed that O3D-LDH and MO presented concentration-dependent toxicity, the binary mixture showed additive effect after exposed to low O3D-LDH concentration (≤ 50 mg/L), but antagonism was observed for the other. It revealed that the agglomeration of O3D-LDH and microalgae influenced chlorophyll content, eventually inhibiting the growth of algae. Overall, this toxicity investigation was critical for understanding the environmental risk of organic LDHs to provide theorical guidance for their practical application in the water purification.

Toxicologic effect and transcriptome analysis for short-term orally dosed enrofloxacin combined with two veterinary antimicrobials on rat liver.

Presently, toxicological assessment of multiple veterinary antimicrobials has not been performed on mammals. In this study, we assessed the short-term toxicity of enrofloxacin (E) combined with colistin (C) and quinocetone (Q). Young male rats were orally dosed drug mixtures and single drugs in 14 consecutive days, each at the dose of 20, 80, and 400 mg/(kg·BW) for environmental toxicologic study. The results showed that at the high dose treatment, the combination of E + C+Q significantly decreased body intake, lymphocytes count on rats; significantly increased the values of Alanine aminotransferase (ALT), Glutamic oxaloacetic transaminase (AST) and, cholinesterase (CHE); it also got the severest histopathological changes, where sinusoidal congestion and a large number of black particles in sinusoids were observed. This means E + C+Q in the high dose groups was able to cause significant damage to the liver. Other combinations or doses did not induce significant liver damage. Transcriptome analysis was then performed on rats in high dose group for further research. For E + C and E + Q, an amount of 375 and 480 differently expressed genes were filtered out, revealing their possible underlying effect on genomes. For E + C+Q, a weighted gene co-expression network analysis was performed and 96 hub genes were identified to reveal the specific effect induced by this combination. This study indicates that joint toxicity should be taken into consideration when involving the risk assessment of these antimicrobials.

Hexavalent chromium amplifies the developmental toxicity of graphene oxide during zebrafish embryogenesis.

Combined toxicity is a critical issue in risk assessment of contaminants. However, very little is known about the joint effects of graphene oxide (GO, a crucial 2-dimensional carbon material) and hexavalent chromium (Cr6+, a widespread heavy metal), particularly with respect to the critical period of embryogenesis. In this study, the combined toxicity of GO and Cr6+ was evaluated through embryo-larval toxicity test in Danio rerio (zebrafish). Results indicated that the co-exposure of Cr6+ (1 mg/L) and GO (0.01 mg/L) inhibited hatching and spontaneous movement of embryos, but no significant changes were found in the single Cr6+ or GO group. Compared with the single GO or Cr6+ exposure, their co-exposure (GO+Cr6+) significantly enhanced the teratogenicity in a concentration-dependent pattern, and the spinal curvature was observed as the main deformity. GO+Cr6+ changed the protein secondary structures of embryos result of the generation of ROS and oxidative stress. The degradations of vertical myosepta and cartilages were observed in co-exposure group, suggesting that GO+Cr6+ disrupted the development of musculoskeletal system. The genes col11a1a, col2a1a and postnb were down-regulated but the genes acta1b and mmp9 were up-regulated by GO+Cr6+. The interactions between Cr6+ and GO demonstrated that the morphology, structure, and surface properties of GO were modified by Cr6+. The enhanced defects and O-containing groups of GO could trap more ß-sheets, induced oxidative stress, disturbed the development of skeletal muscles and cartilages in zebrafish. These data suggested that GO+Cr6+ enhanced their joint toxicity due to the variation of nanoparticle properties. This finding is important for assessing the ecological risk of graphene family nanomaterials in the natural environment.

A novel study for joint toxicity of typical aromatic compounds in coal pyrolysis wastewater by Tetrahymena thermophile.

The coal pyrolysis wastewater (CPW) contributed to aquatic environment contamination with amount of aromatic pollutants, and the research on joint toxicity of the mixture of aromatic compounds was vital for environmental protection. By using Tetrahymena thermophile as non-target organism, the joint toxicity of typical nonpolar narcotics and polar narcotics in CPW was investigated. The results demonstrated that the nonpolar narcotics exerted chronic and reversible toxicity by hydrophobicity-based membrane perturbation, while polar narcotics performed acute toxicity by irreversible damage of cells. As the most hydrophobic nonpolar narcotics, indole and naphthalene caused the highest joint toxicity in 24 h with the lowest EC50mix (24.93 mg/L). For phenolic compounds, the combination of p-cresol and p-nitrophenol also showed the top toxicity (EC50mix = 10.9 mg/L) with relation to high hydrophobicity, and the joint toxicity was obviously stronger and more acute than that of nonpolar narcotics. Furthermore, by studying the joint toxicity of nonpolar narcotics and polar narcotics, the hydrophobicity-based membrane perturbation was the first step of toxicity effects, and afterwards the acute toxicity induced by electrophilic polar substituents of phenols dominated joint toxicity afterwards. This toxicity investigation was critical for understanding universal and specific effects of CPW to aquatic organisms.

Effects of carboxylated multi-walled carbon nanotubes on bioconcentration of pentachlorophenol and hepatic damages in goldfish.

Carboxylated multi-walled carbon nanotubes (MWCNT-COOH) exerts strong adsorption capacity for pentachlorophenol (PCP) and they inevitably co-occur in the environment, but few studies have characterized the effects of MWCNT-COOH on the bioavailability of PCP and its oxidative and tissue damages to fish. In this work, we assessed the PCP accumulation in different organs and the induced oxidative and tissue damages of goldfish following 50-d in vivo exposure to PCP alone or co-exposure with MWCNT-COOH. Our results indicated that PCP bioaccumulation in goldfish liver, gill, muscle, intestine and gut contents was inhibited after co-exposure with MWCNT-COOH in uptake phase. PCP exposure alone and co-exposure with MWCNT-COOH evoked severe oxidative and tissue damages in goldfish bodies, as indicated by significant inhibition of activities of antioxidant enzymes, remarkable decrease in glutathione level, simultaneous elevation of malondialdehyde content, and obvious histological damages to liver and gill. The decreased accumulation of PCP in the presence of MWCNT-COOH led to the reduction of PCP-induced toxicity to liver tissues, as confirmed by the alleviation of hepatic oxidative damages. However, co-exposure groups had higher concentrations of PCP in the tissues than PCP treatment alone (p < 0.05 each) in the depuration phase, revealing that MWCNT-COOH-bound pollutants might pose higher risk once desorbed from the nanoparticles. These results provided substantial information regarding the combined effects of PCP and MWCNT-COOH on aquatic species, which helps to deeply understand the potential ecological risks of the emerging pollutants.

Study on the Joint Toxicity of BPZ, BPS, BPC and BPF to Zebrafish.

Bisphenol Z (BPZ), bisphenol S (BPS), bisphenol C (BPC), and bisphenol F (BPF) had been widely used as alternatives to bisphenol A (BPA), but the toxicity data of these bisphenol analogues were very limited. In this study, the joint toxicity of BPZ, BPS, BPC, and BPF to zebrafish (Danio rerio) was investigated. The median half lethal concentrations (LC50) of BPZ, BPS, BPC, and BPF to zebrafish for 96 h were 6.9 × 105 µM, 3.9 × 107 µM, 7.1 × 105 µM, and1.6 × 106 µM, respectively. The joint toxicity effect of BPF-BPC (7.7 × 105-3.4 × 105µM) and BPZ-BPC (3.4 × 105-3.5 × 105µM) with the same toxic ratio showed a synergistic effect, which may be attributed to enzyme inhibition or induction theory. While the toxicity effect of the other two bisphenol analogue combined groups and multi-joint pairs showed an antagonistic effect due to the competition site, other causes need to be further explored. Meanwhile, the expression levels of the estrogen receptor genes (ERα, ERß1) and antioxidant enzyme genes (SOD, CAT, GPX) were analyzed using a quantitative real-time polymerase chain reaction in zebrafish exposure to LC50 of BPZ, BPS, BPC, and BPF collected at 24, 48, 72, and 96 h. Relative expression of CAT, GPX, and ERß1 mRNA declined significantly compared to the blank control, which might be a major cause of oxidant injury of antioxidant systems and the disruption of the endocrine systems in zebrafish.

Nanosized titanium dioxide UV filter increases mixture toxicity when combined with parabens.

To address the concern about the environmental impact of engineered nanoparticles frequently used in the recently marketed personal care and hygiene products (PCPs), we conducted a toxicity assessment and determined the EC50 values of the nanosized inorganic UV filter TiO2 (nano-TiO2), as well as those of the organic UV filter oxybenzone (BP3) and three parabens (methyl, propyl, and benzylparaben) present in most PCPs formulation. The bioassays were carried out through standardized toxicity bioassays on two environmentally relevant aquatic species i.e. Daphnia magna and Phaeodactylum tricornutum. For nano-TiO2 48 h EC50 on D. magna was 3.09 mgL-1 and for parabens ranged from 32.52 to 1.35 mgL-1. The two most toxic compounds on D. magna, nano-TiO2 and benzylparaben (BzP), were further tested with the algae. For nano-TiO2 72 h EC50 value was 2.27 mgL-1 and for BzP it was 10.61 mgL-1. In addition, D. magna was exposed to selected binary mixtures of the target compounds i.e. nano-TiO2+BP3, nano-TiO2+BzP and BP3+BzP On the endpoint of 48 h, a synergistic action was observed for nano-TiO2+BP3 and nano-TiO2+BzP, but an antagonistic effect occurred in the mixture BP3+BzP. These findings suggest that nano-TiO2 can increase the toxicity of the mixture when combined with other compounds.

Roles of mtDNA damage and disordered Ca2+ homeostasis in the joint toxicities of cadmium and BDE209.

Cadmium, a typical heavy metal, causes serious toxicities on many organs and tissues. As the last partially controlled class of polybrominated diphenyl ethers (PBDEs), BDE209 can also induce various health issues. Although apoptosis mediated by mitochondria has been known to be a key player in inducing toxicities by cadmium, the detailed mechanisms are incompletely understood. Moreover, co-existence of cadmium and PBDEs has been found in various environment context and human body. However, studies on the joint toxicity of cadmium and PBDEs are still limited with largely unknown mechanisms. In the present study, we investigated the adverse effects and mechanisms of single or combined treatment of CdCl2 and BDE209 on hepatocytes. We observed that apoptosis were significantly induced by CdCl2, and the combined treatment of CdCl2 and BDE209 greatly promoted the progression of apoptosis. BDE209 induced mild apoptosis. Mitochondria was the pivot of several mechanisms to induce apoptosis, including ROS production, decreased mitochondrial membrane potential (MMP), mtDNA damage and disordered calcium (Ca2+) homeostasis. However, we found that mtDNA damage and disordered Ca2+ homeostasis were the main mechanisms for CdCl2-induced apoptosis while ROS production played important roles in BDE209-induced apoptosis. Less mtDNA damage occurred in BDE209-treated cells. In the cells with combined treatment, CdCl2 and BDE209 exhibited a complementary pattern for the underlying mechanisms of apoptosis, leading to the joint toxicities, in which CdCl2 showed more contributions. In a conclusion, our results demonstrated that combined exposure to cadmium and BDE209 causes joint adverse effects on hepatocytes through diverse mechanisms as mediated by mitochondria.

A novel computational solution to the health risk assessment of air pollution via joint toxicity prediction: A case study on selected PAH binary mixtures in particulate matters.

Regional haze episode has already caused overwhelming public concern. Unraveling the health effects of the representative composition mixtures of atmospheric fine particulate matters (PM2.5) becomes a top priority. In this study, a novel computational solution integrating chemical-induced genomic residual effect prediction with in vitro-based risk assessment is proposed to obtain the cumulative health risk of typical chemical mixtures of particulate matters (PM). The joint toxicity of binary mixtures is estimated by analyzing both genomic similarity and dose-response curve of relevant pollutants for the chemical-induced genomic residual effect. Specifically, the modified relative potency factor (mRPF) of mixtures is introduced for this purpose, and the ratio of activation (RA) value is defined to assess the corresponding health risks of the mixtures. As a methodology demonstration, the health risk of typical binary polycyclic aromatic hydrocarbon (PAH) mixtures in PM, containing Benzo[a]pyrene (BaP) as a component, is assessed using the proposed solution. Our results indicate that the combined effect of pairwise PAHs of BaP with Benzo[b]fluoranthene (BbF) and Benz[a]anthracene (BaA) is synergistic on p53 pathway, and that the health risk of the such mixtures increases compared to that of the individual ones. Obviously, the cumulative health risk of environmental mixtures will be underestimated when the synergistic effect is wrongly assumed to be additive. To our knowledge, this is the first study ever report on a computational solution to the health risk assessment of environmental pollution via joint toxicity prediction. The novel methodology proposed here makes full use of the open-access in vitro assay data and transcriptomic information in literatures and provides a successful demonstration of the concept of systems biology and translational science.

Synergistic Effects of The Enhancements to Mitochondrial ROS, p53 Activation and Apoptosis Generated by Aspartame and Potassium Sorbate in HepG2 Cells.

The safety of food additives has been widely concerned. Using single additives in the provisions of scope is safe, but the combination of additives, may induce additive, synergy, antagonism and other joint effects. This study investigated the cytotoxicity of aspartame (AT) together with potassium sorbate (PS). Thiazolyl Blue Tetrazolium Bromide (MTT) assay indicated that AT and PS had IC50 values of 0.48 g/L and 1.25 g/L at 24 h, respectively. High content analysis (HCA) showed that both AT and PS had a negative effect on mitochondrial membrane potential (MMP), reactive oxygen species (ROS) and DNA damage while the joint group behaved more obviously. The biochemical assays revealed typical cell morphological changes and the activation of cytochrome c and caspase-3 verified apoptosis induced by AT together with PS. With dissipation of MMP and increase of cell membrane permeability (CMP), it indicated AT together with PS-induced apoptosis was mediated by mitochondrial pathway. Meanwhile, p53 were involved in DNA damage, and the ratio of Bax/Bcl-2 was increased. Moreover, excessive ROS induced by AT together with PS is a key initiating factor for apoptosis. All these results proved that p53 was involved in apoptosis via mitochondria-mediated pathway and the process was regulated by ROS.