Combined cytotoxic effects of pesticide mixtures present in the Chinese diet on human hepatocarcinoma cell line

Nonadditive Cytotoxicity in Select Disinfection Byproducts and Disinfected Secondary Effluents

Toxicity studies of water disinfection byproducts (DBPs) typically assume additive interactions. Coupling results from both the bottom-up cytotoxicity interaction approach by selecting six common DBPs and the top-down cytotoxicity fractionating the disinfected secondary effluent containing a much broader DBP selection, we demonstrated a novel effect of clear, nonadditive cytotoxicity at low chemical concentrations regardless of the number of DBP types involved. We revealed that the cytotoxicity interactions were influenced by the chemical's type, concentration factor, and mixing ratio. For the bottom-up approach, the average combination indices (CIs) were 1.61 (chloracetamide + chloroacetonitrile, antagonism), 1.03 (bromoacetamide+bromoacetonitrile, near additivity), and 0.69 (iodoacetamide + iodoacetonitrile, synergism) across the DBPs' concentration range of 10-4-10-7 M. These cytotoxicity interactions also varied with the components' mixing ratios. For the top-down approach, we obtained two fractions of DBP mixtures from the disinfected secondary effluent using solvents of different polarities. The effect of the concentration on CI values was significant, with a maximum 43.1% relative deviation in CI from LC5 to LC95. The average CI values across the sample concentration range of 1-50 × (concentration factor) varied from 1.68 (antagonism) to 0.89 (slight synergism) as the ratio of mixture A increased. These results call for further research in prioritizing the forcing DBPs in mixtures.

Biomimetic cytotoxicity control of select nitrogenous disinfection byproducts in water

Nitrogenous disinfection byproducts (N-DBPs) in water are carcinogenic, teratogenic, and mutagenic. In this work, we developed a biomimetic reduction approach based on the cysteine thiol that destructed the highly toxic, select nitrogenous haloacetamides (HAMs) and haloacetonitriles (HANs) while effectively controlling the cytotoxicity of the degradation products to serve as a basis for further technological applications (e.g. immobilized contact bed for terminal users). Mechanisms on toxicity control were elucidated. Results showed the degradation and cytotoxicity control of HAMs as more efficient than that of the HANs. The cytotoxicity of the chlorinated, brominated, and iodinated HAMs and HANs was reduced to 25 %- 0.25 % of the original after biomimetic reduction using a reasonable concentration ratio. Through a combination of thiol-specific reactivity, dehalogenation, and quantitative structure-activity relationship analyses, the major toxicity control mechanisms were found to be the reductive dehalogenation of the N-DBPs. The halogenated functional groups on the N-DBPs had a more pronounced effect than the amide and nitrile groups on the cytotoxicity and detoxification effect. Patterns of toxicity interaction variations with DBPs concentrations were identified to detect possible synergistic cytotoxicity interactions under various combinations of HAMs and HANs in the presence of the cysteine thiol. Results could benefit future N-DBPs control efforts.

Hormone effects of eighteen bisphenol analogues and their effects on cellular homeostasis and the typical signal pathways

Through the transfer chain of surroundings from feed to the farmed-animals and ultimately the corresponding livestock and poultry products, people are exposed to large amounts of bisphenol analogues (BPs), such as rational emissions from manufacturing plants, feed packaging bags and food packaging contact. Some BPs have been reported to show certain toxicological effects, especially, estrogen and endocrine disrupting effect. With the increasing application of BPs, the problem is becoming more and more serious. We systematically studied the hormonal effects of 18 BPs and their effects on cell homeostasis and classical signaling pathways by using classical E-SCREEN assay, fluorescent probes and western blotting. The results confirmed the estrogen-like effect of 13 BPs and 6 BPs obtained high docking scores (Scores < -9.0) for the three receptors simultaneously with the main interactions of hydrophobic, hydrogen and π-stacking of T-type bonds. BPAP regulates cells via apoptosis and steroid signaling pathway by intracellular ROS and mitochondrial followed the caspase pathway. BPE and BPS were involved in the classical NF-κB and Hippo signaling pathways. All data provides scientific basis for the safety risk assessment of endocrine disrupting and cellular homeostasis evaluation of BPs as chronic environmental pollution.

Biodegradation of soil agrochemical contamination mitigates the direct horizontal transfer risk of antibiotic resistance genes to crops

Microorganisms can drive a substrate-specific biodegradation process to mitigate soil contamination resulting from extensive agrochemical usage. However, microorganisms with high metabolic efficiency are capable of adapting to the co-occurrence of non-substrate contaminants in the soil (particularly antibiotics). Therefore, the utilization of active microorganisms for biodegradation raises concerns regarding the potential risk of antibiotic resistance development. Here, the horizontal transfer risk of antibiotic-resistance genes (ARGs) in the soil-plant biota was assessed during biodegradation by the newly isolated Proteus terrae ZQ02 (which shortened the half-life of fungicide chlorothalonil from 9.24 d to 2.35 d when exposed to tetracycline). Based on metagenomic analyses, the distribution of ARGs and mobile genetic elements (MGEs) was profiled. The ARGs shared with ∼118 core genes and mostly accumulated in the rhizosphere and maize roots. After ZQ02 was inoculated, the core genes of ARGs reduced significantly in roots. In addition, the Pseudomonas and Proteus genera were identified as the dominant microbial hosts of ARGs and MGEs after ZQ02 adoption. The richness of major ARG hosts increased in soil but barely changed in the roots, which contributed to the mitigation of hosts-mediated ARGs transfer from soil to maize. Finally, the risk of ARGs has been assessed. Compared with the regular planting system, the number of risky ARGs declined from 220 (occupied 4.77 % of the total ARGs) to 143 (occupied 2.67 %) after biodegradation. Among these, 23 out of 25 high-risk genes were aggregated in the soil whereas only 2 genes were identified in roots, which further verified the low antibiotic resistance risk for crop after biodegradation. In a nutshell, this work highlights the critical advantage of ZQ02-based biodegradation that alleviating the ARGs transfer risks from soil to crop, which offers deeper insights into the versatility and feasibility of bioremediation techniques in sustainable agriculture.

Comparative assessment of individual and mixture chronic toxicity of glyphosate and glufosinate ammonium on amphibian tadpoles: A multibiomarker approach

The aim of the present study was to assess the ecotoxicity of glyphosate and glufosinate ammonium mixtures on amphibian tadpoles and the potential impact of mixture in aquatic ecosystems health. The bonding properties of the mixture based on computational chemistry and an experimental bioassay on morphology, DNA damage and biochemical biomarkers on tadpoles of the common toad Rhinella arenarum were studied. The results of the density functional theory analysis showed trends of the pesticides clustering to form exothermic mixtures, suggesting the likelihood of hot-spots of pesticides in real aquatic systems. In addition, biological effects of individual pesticides and the mixture were studied on tadpoles over 45 days-chronic bioassay. The bioassay consisted of four treatments: a negative control (CO), 2.5 mg L^-1 of a glyphosate-based herbicide (GBH), 2.5 mg L^-1 of a glufosinate ammonium-based herbicide (GABH) and their 50:50 (% v/v) mixture (GBH-GABH). Morphological abnormality rates were significantly higher in all herbicide treatments with respect to CO at 48 h of exposure. Abdominal edema was the most frequent type of abnormality recorded at 48 h, 10 and 45 days of exposure. DNA damage was recorded in all herbicides treatments. Thyroxin increased only in GABH treatment. Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) significantly increased in GBH treatment, indicating a GBH-neurotoxic effect. Glutathione S-transferase decreased in GABH and GBH-GABH treatments, while catalase decreased in individual GBH and GABH treatments. Overall, teratogenicity, DNA damage, hormonal disruption (T4), and oxidative stress were greater in GABH-treated tadpoles than GBH-treated tadpoles. This study also highlights the robust chemical interaction between the active ingredients of both herbicides, which is reflected on antagonisms in most of analyzed biomarkers, as well as potentiation and additivity in others. Based on our results, the GABH had a higher toxicity than GBH for amphibian tadpoles.

Rapid Detection of Malathion, Phoxim and Thiram on Orange Surfaces Using Ag Nanoparticle Modified PDMS as Surface-Enhanced Raman Spectroscopy Substrate

Malathion, phoxim, and thiram are organophosphates and organosulfur pesticides widely used in agricultural products. The residues of these pesticides present a direct threat to human health. Rapid and on-site detection is critical for minimizing such risks. In this work, a simple approach was introduced using a flexible surface-enhanced Raman spectroscopy (SERS) substrate. The prepared Ag nanoparticles-polydimethylsiloxane (AgNPs-PDMS) substrate showed high SERS activity, good precision (relative standard deviation = 5.33%), and stability (30 days) after optimization. For target pesticides, the linear relationship between characteristic SERS bands and concentrations were achieved in the range of 10~1000, 100~5000, and 50~5000 μg L-1 with LODs down to 3.62, 41.46, and 15.69 μg L-1 for thiram, malathion, and phoxim, respectively. Moreover, SERS spectra of mixed samples indicated that three pesticides can be identified simultaneously, with recovery rates between 96.5 ± 3.3% and 118.9 ± 2.4%, thus providing an ideal platform for detecting more than one target. Pesticide residues on orange surfaces can be simply determined through swabbing with the flexible substrate before acquiring the SERS signal. This study demonstrated that the prepared substrate can be used for the rapid detection of pesticides on real samples. Overall, this method greatly simplified the pre-treatment procedure, thus serving as a promising analytical tool for rapid and nondestructive screening of malathion, phoxim, and thiram on various agricultural products.

Study of eighteen typical bisphenol analogues as agonist or antagonist for androgen and glucocorticoid at sub-micromolar concentrations in vitro

Bisphenol A and its substitutions are commonly used to manufacture epoxy resins, plastic materials and different kinds of daily necessities. In this process, a large number of bisphenol analogues (BPs) are continuously released directly/indirectly into the environment. Through the chain of environment-feed-farmed-animals-livestock and poultry products, BPs present the low concentration but chronic exposure for surroundings and environment. In addition, BPs have been revealed by extensive studies as emerging endocrine disruptors, whose effects on androgens/glucocorticoids have rarely been mentioned in previous reports. The (anta-) agonist/antagonist properties of 18 classic BPs were investigated in vitro: We assessed the cytotoxicity and examined the luciferase induction values of BPs in MDA-kb2 cells, incubated single or co-incubated with dihydrotestosterone (DHT), dexamethasone, flutamide and RU486 for 24 h. From the concentration of 10^-10 to 10^-5 M, BPs had negligible cytotoxicity for MDA-kb2 cells, except for 4,4'-(9-Fluorenylidene)diphenol with the IC₅₀ 1.32 μM. All 18 BPs had the response to androgen/glucocorticoid receptors (AR/GR). BPs at nanomolar and trace concentrations are agonists, while BPs at micromolar and higher concentrations are antagonists. Molecular docking showed that BPs interact with AR/GR through hydrophobic bonds, hydrogen bonds, T-type π-stacking and water-bridge. These experimental data demonstrate the universality of the endocrine-disrupting effects of BPs and suggest the urgency of paying attention to the usages of BPs.

Three widely used pesticides and their mixtures induced cytotoxicity and apoptosis through the ROS-related caspase pathway in HepG2 cells

Difenoconazole, cypermethrin and triazophos are widely used pesticides in agricultural production and frequently detected in foods. The aim of this study was to determine the effect of these pesticides and their mixtures on cell viability, reactive oxygen species (ROS), lactate dehydrogenase (LDH) content, apoptosis rate and DNA fragmentation and synthesis in human hepatocellular carcinoma cells (HepG2). The order of inhibitory effects for the individual pesticides was ranked as difenoconazole > cypermethrin > triazophos. The enhanced expression of caspase-3, caspase-7 and PARP activity was observed in HepG2 cells, which was 1.7, 1.3 and 1.6-fold higher than the control, respectively, along with significant protein cleavage; and induced apoptosis in a concentration-dependent manner. Further, the pesticide mixtures significantly increased ROS level (up to 1.3-fold), induced DNA fragmentation (up to 1.8-fold), inhibited DNA synthesis (up to 53%), and damaged the cells by destroying the cell membrane and producing a large amount of LDH at concentration range of 10-30 μM. Specifically, mixtures containing difenoconazole showed stronger toxicities than individual pesticides, implying higher health risks associated with mixtures. Our results show that three widely used pesticides exhibited cytotoxicity and apoptosis through the ROS-related caspase pathway, providing a basis for evaluation of health risks from pesticide mixtures via food consumption.

Analysis of pesticide residues in commercially available chenpi using a modified QuEChERS method and GC-MS/MS determination

To ensure the safety of the commercially available chenpi, a convenient and fast analytical method was developed for the determination of 133 pesticide residues in chenpi using gas chromatography-tandem mass spectrometry (GC-MS/MS). In this study, different extraction solvents, redissolution solvents and adsorbents were tested according to the recovery and purification effect to obtain a modified QuEChERS method. The samples were extracted with acetonitrile. During the clean-up step, octadecyl-modified silica (C18) and graphitized carbon black (GCB) were selected, and aminopropyl (NH₂) was used instead of primary secondary amine (PSA) because of its weaker ion exchange capacity which had little effect on the recovery of ditalimfos. Samples were quantified by matrix-matched calibration with internal standards. All pesticides showed good linearity in the respective range, both with values of r² > 0.99. The average recoveries of the pesticides spiked samples ranged from 70.0% to 112.2% with the RSDs of 0.2%–14.4%. The modified QuEChERS method was validated and applied to twenty real samples. Five pesticides were found in eight batches, but no pesticide exceeded the maximum residue limits (MRL, MRL reference to European commission).

Antibiotics may increase triazine herbicide exposure risk via disturbing gut microbiota

BACKGROUND

Antibiotics are commonly used worldwide, and pesticide is a kind of xenobiotic to which humans are frequently exposed. The interactive impact of antibiotics on pesticides has rarely been studied. We aim to investigate the effects of antibiotics on the pesticide exposure risk and whether gut microbiota altered by antibiotics has an influence on pesticide bioavailability. Furthermore, we explored the mechanisms of gut microbiota affecting the fate of pesticides in the host.

RESULTS

The oral bioavailability of triazine herbicides significantly increased in the rats treated with ampicillin or antibiotic cocktails. The antibiotic-altered gut microbiota directly influenced the increased pesticide bioavailability through downregulating hepatic metabolic enzyme gene expression and upregulating intestinal absorption-related proteins.

CONCLUSIONS

Antibiotics could increase the pesticide bioavailability and thereby may increase the pesticide exposure risk. The antibiotic-altered gut microbiota that could alter the hepatic metabolic enzyme gene expression and intestinal absorption-related proteome was a critical cause of the increased bioavailability. This study revealed an undiscovered potential health impact of antibiotics and reminded people to consider the co-exposed xenobiotics when taking antibiotics.

Potential chromosome damage, cell-cycle kinetics/and apoptosis induced by epoxiconazole in bovine peripheral lymphocytes in vitro

The epoxiconazole was tested in vitro for its potential on induction of chromosome damage and/or cell cycle kinetics in cultured bovine peripheral lymphocytes. Cytogenetic endpoints such as: Chromosome Aberrations (CA); Sister Chromatid Exchanges (SCE); Micronuclei (MN); Mitotic Index (MI); Proliferation Index (PI); and Cytokinesis Block Proliferation Index (CBPI) were investigated for 24 h and 48 h of incubation. The cultured lymphocytes were exposed to the epoxiconazole at concentrations of 2.5, 5, 10, 25, 50 and 100 μg mL^-1. From our results is evident that treatment of bovine peripheral lymphocytes with the epoxiconazole was not related to DNA damage; no genotoxic effect and/or clastogenic/aneugenic effects were recorded. However, epoxiconazole has ability to significantly affect cell cycle kinetics/and induce apoptosis. A decrease of proliferation in the MI, CBPI and identically in the PI were observed; hence, cytostatic/cytotoxic effects of epoxiconazole have been recorded. The prolonged time of exposure at the highest concentration caused an inhibition of the replication. Electrophoretic analysis confirmed the epoxiconazole potential to induce ladder-like patterns of DNA fragments that are a hallmark of apoptosis.