Animal Carcinogenicity Research Articles

Apocynin protects the dopaminergic cell line SH-SY5Y from fumonisin B1 induced cytotoxicity through attenuation of oxidative stress mediated apoptosis

BackgroundThe fusarium verticillioides produces the mycotoxin fumonisin b1 (Fb1), commonly infects corn and other agricultural commodities. The Fb1 showed hepatotoxicity, cytotoxicity, and carcinogenicity in animals. Aim of the studyThere are limited literature available on cytotoxicity exerted by Fb1. Hence, the present investigation aimed to evaluate the cytotoxic effects of Fb1 and its mechanism in the neuroblastoma (SH-SY5Y) cell line and its amelioration by apocynin. MethodsWe investigated the molecular mechanism of Fb1-induced cytotoxicity in SH-SY5Y cells and investigated the effect of Fb1 oxidative stress markers, and apoptosis. ResultsThe results explained that the Fb1 showed dose-dependent cytotoxicity in SH-SY5Y cells with the IC50 value 150 µM. Fb1 elevated reactive oxygen species and depolarized mitochondrial membrane potential, vacuolation and apoptotic changes were observed in SH-SY5Y cells. The protein expression of CAT and GPx were downregulated with Fb1 treatment, and apoptotic markers caspase-3 and caspase-8 were upregulated. When the apocynin was pretreated, followed by Fb1 exposure for 24 h, all the changes were normalized with the treatment. Hence, these results suggest that ROS is the primary upstream signal leading to increased Fb1-mediated cytotoxicity in SH-SY5Y cells. ConclusionApocynin reversed the Fb1-induced oxidative stress and apoptosis by its antioxidant potency in SH-SY5Y cell lines.

Determination of Total Aflatoxins in Polished Rice by Liquid Chromatography-Fluorescence Detection with Multifunctional Column Cleanup and Precolumn Derivatization: Single-Laboratory and Inter-Laboratory Validation Studies.

Aflatoxins are toxic metabolites produced by Aspergillus spp. Because aflatoxins are potent carcinogens in humans and animals, many countries have set regulatory limits for aflatoxins in foods to prevent dietary exposure. From a global food safety perspective, in 2023, the Codex Alimentarius Commission established the maximum level (ML) of total aflatoxins in certain cereals and cereal-based products, including polished rice. Therefore, validated analytical methods for aflatoxin detection are necessary. In this study, a high performance liquid chromatography (HPLC)-fluorescence method coupled with multifunctional column clean-up and trifluoroacetic acid derivatization was developed for the determination of aflatoxin levels in polished rice. Our method was validated in a single laboratory study using aflatoxin-spiked materials, followed by an inter-laboratory validation study. Twelve laboratories participated in the inter-laboratory validation study, and five polished rice test samples artificially contaminated with aflatoxins were analyzed. In a single laboratory study, the ranges of mean recoveries of aflatoxin B1, B2, G1, G2, and total aflatoxins were 101%, 100-103%, 93-96%, 95-98%, and 97-99%, respectively. The relative standard deviations for within-day and between-day variations were all ≤ 4.4%. In the inter-laboratory validation study, the relative standard deviations for repeatability and reproducibility were from 0.7 to 2.7% and 3.3 to 8.9% for all analytes, respectively. In response to the Codex ML and method performance criteria for aflatoxins in polished rice, an analytical method based on HPLC-fluorescence detection was developed. All method performance parameters estimated from the testing results of the single-laboratory and inter-laboratory validation studies met the criteria required by the Codex. Single- and inter-laboratory studies for the validation of an analytical method for aflatoxin level determination in polished rice were successfully performed. This analytical method will be suitable to determine aflatoxin levels around the Codex ML set for polished rice.

Prevalence and concentration of mycotoxins in bovine feed and feed components: A global systematic review and meta-analysis

Mycotoxins are secondary metabolites produced by fungi and identified as contaminants in animal feed. They have potentially harmful effects, including carcinogenicity, mutagenicity, and repro-toxicity in animals and humans. As a result of climate change, there is the potential for a change in the prevalence and concentration of mycotoxins in animal feed components. This necessitates an assessment of the present and emerging threats to the food supply chain from mycotoxins. This systematic review and meta-analysis study synthesised studies on mycotoxin contamination and prevalence in cattle feed components. The studies were collected from scientific databases Web of Knowledge, Scopus, and Embase between 2011 and 2022. The meta-analysis synthesised 97 studies on the prevalence and the concentration of aflatoxins, ochratoxin A, deoxynivalenol, zearalenone, fumonisin and T-2/HT-2 toxins in feed components. Aflatoxin was highly prevalent (59 %), with a concentration of 2.58–3.92 μg kg−1 in feed components. Ochratoxin A had a global prevalence of 31 % with a concentration of 5.56–12.41 μg kg−1. Deoxynivalenol had a global concentration of 233.17–327.73 μg kg−1 and a prevalence of 74 %. Zearalenone had a prevalence of 70 % and a concentration of 42.47–66.19 μg kg−1. The concentration and prevalence of fumonisins was 232.19–393.07 μg kg−1 and 65 %, respectively. The prevalence and concentration of T-2/HT-2 toxins were 45 % and 23.54–35.12 μg kg−1, respectively. The synthesised concentration of the mycotoxins in the overall feed components was lower than the regulated and guidance values set by the European Union. However, in a few cases, the 95th percentile exceeded these concentration values due to high levels of uncertainty attributed to lower sample size, and thus, need to be considered while conducting risk assessments. The study highlights climates and regions likely to be conducive to the emergence of mycotoxin risk, especially considering the potential influences of climate change.

An update on the formation in tobacco, toxicity and carcinogenicity of N'-nitrosonornicotine and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone.

The tobacco-specific nitrosamines N'-nitrosonornicotine (NNN) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) are considered 'carcinogenic to humans' by the International Agency for Research on Cancer (IARC) and are believed to be important in the carcinogenic effects of both smokeless tobacco and combusted tobacco products. This short review focuses on the results of recent studies on the formation of NNN and NNK in tobacco, and their carcinogenicity and toxicity in laboratory animals. New mechanistic insights are presented regarding the role of dissimilatory nitrate reductases in certain microorganisms involved in the conversion of nitrate to nitrite that leads to the formation of NNN and NNK during curing and processing of tobacco. Carcinogenicity studies of the enantiomers of the major NNK metabolite 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) and the enantiomers of NNN are reviewed. Recent toxicity studies of inhaled NNK and co-administration studies of NNK with formaldehyde, acetaldehyde, acrolein and CO2, all of which occur in high concentrations in cigarette smoke, are discussed.

Pathologists’ perspective on the study design, analysis, and interpretation of proliferative lesions in a lifetime rodent carcinogenicity bioassay of sucralose

Sucralose, a sugar substitute first approved for use in 1991, is a non-caloric sweetener regulated globally as a food additive. Based on numerous experimental animal studies (dating to the 1980s) and human epidemiology studies, international health agencies have determined that sucralose is safe when consumed as intended. A single lifetime rodent carcinogenicity bioassay conducted by the Ramazzini Institute (RI) reported that mice fed diets containing sucralose develop hematopoietic neoplasia, but controversy continues regarding the validity and relevance of these data for predicting health effects in humans. The present paper addresses the controversy by providing the perspective of experienced pathologists on sucralose-related animal toxicity and carcinogenicity data generally, and the RI carcinogenicity bioassay findings specifically, using results from publicly available papers and international regulatory authority decisions. In the authors’ view, flaws in the design, methodology, data evaluation, and reporting of the RI carcinogenicity bioassay for sucralose diminish the value of the data as evidence that this agent represents a carcinogenic hazard to humans. This limitation will remain until the RI bioassay is repeated under Good Laboratory Practices and the design, data, and accuracy of the pathology diagnoses and interpretations are reviewed by qualified pathologists with experience in evaluating potential chemically-induced carcinogenic hazards.

Ochratoxin A detoxification potentials of basil, chan, and chia seeds.

The most toxic of the ochratoxins is ochratoxin A (OTA), which is primarily produced by species of Aspergillus and Penicillium that can be found in maize, wheat, coffee, red wine, and various grains. OTA induces immunotoxicity, nephrotoxicity, hepatotoxicity, teratogenicity, and carcinogenicity in both animals and humans. Thus, there is a need to identify mycotoxin detoxification agents that can effectively decontaminate OTA. Seeds of basil (Ocimum basilicum L.), chan (Hyptis suaveolens L.), and chia (Salvia hispanica L.) are functional foods capable of eliminating harmful substances. Despite this potential, the impact of these seeds on OTA detoxification remains unclear. This study reveals that milled basil, chan, and chia seeds adsorb significant levels of OTA, with chia demonstrating the highest adsorption capacity, followed by chan and basil seeds showing the least efficiency. Furthermore, milled basil, chan, and chia seeds effectively reduced OTA residues in artificial gastric and intestinal fluids, where they achieved up to 93% OTA adsorption in the former. In addition, these milled seeds were able to remove OTAs from canned, drip, and instant coffee. This study is the first to report the OTA elimination potential of basil, chan, and chia seeds.

The role of microRNAs in acrylamide toxicity.

The chemical compound known as Acrylamide (AA) is employed in different industries worldwide and is also found in thermal-processed food. AA has been acting as a reproductive toxicant, carcinogen, and neurotoxic in various animals, which may promote several toxic impacts in animal and human species. Up to now, various studies have focused on the harmful mechanisms and intervention actions of AA. However, the underlying mechanisms that AA and its toxic effects can exert have remained uncertain. MicroRNAs (miRNAs) are a class of short, non-coding RNAs that are able to act as epigenetic regulators. These molecules can regulate a wide range of cellular and molecular processes. In this regard, it has been shown that different chemical agents can dysregulate miRNAs. To determine the possible AA targets along with mechanisms of its toxicity, it is helpful to study the alteration in the profiles of miRNA regulation following AA intake. The current research aimed to evaluate the miRNAs' mediatory roles upon the AA's toxic potentials. This review study discussed the AA, which is made within the food matrix, the way it is consumed, and the potential impacts of AA on miRNAs and its association with different cancer types and degenerative diseases. The findings of this review paper indicated that AA might be capable of altering miRNA signatures in different tissues and exerting its carcinogen effects.

Determination of Aflatoxins in Pig Feed. Using the Thin Layer Chromatography Technique

Aflatoxins are the most important mycotoxins in terms of food safety, due to their frequency and toxicity, they are characterized by being secondary metabolites synthesized by fungi. In order to determine the presence of aflatoxins in pork feed, five samples from different commercial companies were analyzed. The methodology used prior to the sample extraction process was the thin layer chromatography technique, observed using long-wave ultraviolet light. It could be seen in samples 1,3,4,5, the presence of Aflatoxins, toxicogenic strains of Aspergillus parasiticus, which produce aflatoxins, G1 and G2, is characterized by the fluorescence coloration, in sample 2 the presence was observed of aflatoxins toxicogenic strains of Aspergillus flavus. Toxigenic strains of Aspergillus flavus generally produce only aflatoxins B1 and B2, while toxicogenic strains of Aspergillus parasiticus produce aflatoxins B1, B2, G1 and G2. AFB1 aflatoxins have been considered obvious carcinogens in experimental animals. It is important to carry out systematic research with low-cost analytical techniques to understand the mechanisms of production and action of aflatoxins in foods, in order to prevent, monitor and control these types of toxins.

Confidence score calculation for the carcinogenic potency categorization approach (CPCA) predictions for N-nitrosamines

We present a method for computing confidence in the Carcinogenic Potency Categorization Approach (CPCA) based predictions for N-nitrosamines. Our method relies on capturing local structural variations surrounding the nitrosamine core, which can significantly influence potency and may introduce uncertainty into predictions relying on these features.We use continuous-valued fingerprints to conduct a specialized neighborhood analysis, grouping nitrosamines with similar local features. Using a reference dataset of 7679 potential Nitrosamine Drug Substance Related Impurities (NDSRIs) with pre-computed CPCA-derived Acceptable Intake (AI) limits, we gauge the prediction confidence for a given query N-nitrosamine by evaluating the distances and CPCA derived potency category distribution among neighboring NDSRIs. Our methodology allows for a nuanced assessment of CPCA's discrete four-level outcomes (i.e. 18/26.5, 100, 400, and 1500 ng AI limits). It enables the differentiation of robust predictions from potentially uncertain ones, for instance, cases where low confidence arises from rare structural features in the query nitrosamine, helpful in regulatory decision-making.In our analysis of 30 nitrosamines with animal carcinogenicity data, we often observed lower confidence scores when experimental TD50 values significantly disagreed with CPCA-calculated potency. Moreover, lower confidence scores were associated with greater variability in the predicted α-carbon hydroxylation potential of neighboring compounds. In a list of 265 NDSRIs with established regulatory AI limits, approximately 68% received strong confidence scores for accurate CPCA potency class predictions. However, 8% received poor confidence in potency class predictions, as well as lacked sufficient neighbor support due to uncommon structural features.

A New Benzaldehyde Derivative Exhibits Antiaflatoxigenic Activity against Aspergillus flavus.

Aflatoxin B1 (AFB1) is the most potent naturally occurring carcinogen for humans and animals produced by the common fungus Aspergillus flavus (A. flavus). Aflatoxin (AF) contamination in commodities is a global concern related to the safety of food and feed, and it also impacts the agricultural economy. In this study, we investigated the AFB1-inhibiting activity of a new benzaldehyde derivative, 2-[(2-methylpyridin-3-yl)oxy]benzaldehyde (MPOBA), on A. flavus. It was found that MPOBA inhibited the production of AFB1 by A. flavus, with an IC50 value of 0.55 mM. Moreover, the inhibition of conidiation was also observed at the same concentration. The addition of MPOBA resulted in decreased transcript levels of the aflR gene, which encodes a key regulatory protein for the biosynthesis of AF, and also decreased transcript levels of the global regulator genes veA and laeA. These results suggested that MPOBA has an effect on the regulatory mechanism of the development and differentiation of conidia, leading to the inhibition of AFB1 production. In addition, the cytotoxicity study showed that MPOBA had a very low cytotoxic effect on the Madin-Darby canine kidney (MDCK) cell line. Therefore, MPOBA may be a potential compound for developing practically effective agents to control AF contamination.

Sex difference in the non-linear relationship between ethylene oxide exposure and depressive symptoms: A cross-sectional study

BackgroundEthylene oxide (EO) has been recognized as an animal carcinogen and environmental EO exposure was linked to several diseases. However, the association of EO exposure with depression prevalence is still not clear. MethodsWe included 6016 participants with complete data on HbEO concentrations, depression diagnosis, and necessary covariates using the 2013–2020 National Health and Nutrition Examination Survey. Weighted multivariable logistic model was applied to examine the association of HbEO concentrations with depression risk. Weighted restricted cubic spline model was applied to draw the dose-response curve. ResultsIn the total population, individuals in the second, third, and fourth quartile of HbEO respectively had an adjusted OR of 0.99 (95%CI: 0.60, 1.63), 1.13 (95%CI: 0.73, 1.75), and 2.87 (95%CI: 1.86, 4.45) (Ptrend < 0.001) for depression with a significant “J” shaped non-linear dose-response relationship (Pnon-linear < 0.001). Females, drinkers, and smokers were susceptible to the depressive effect of EO. Doubling the HbEO concentrations was respectively associated with a 1.50-fold (95%CI: 1.25, 1.79), 1.29-fold (1.15, 1.44), and 1.17-fold (1.04, 1.33) increased risk of depression for females, drinkers, and smokers. LimitationsCross-sectional study design and self-reported depressive symptoms. ConclusionsEnvironmental EO exposure was associated with increased depression risk, especially among females, drinkers, and smokers. Further prospective studies are required to affirm these findings.

A comparison of the exposure system of glycidol-related chemicals on the formation of glycidol-hemoglobin adducts.

Glycidol fatty acid esters that are present in foods are degraded invivo to the animal carcinogen glycidol, which binds to the N-terminal valine of hemoglobin (Hb) to form N-(2,3-dihydroxypropyl)valine (diHOPrVal) adducts. The existence of other chemicals that are converted to glycidol is unknown. To determine the effect of different exposure conditions on the formation of diHOPrVal adducts, several glycidol-related chemicals (3-monochloropropane-1,2-diol; 3-MCPD, epichlorohydrin, glyceraldehyde, acrylic acid, and 1,2-propanediol) were evaluated using invitro and invivo (single/repeated dose) methods. Invitro, the reaction of 3-MCPD or epichlorohydrin with human Hb produced 17% and 0.7% of diHOPrVal, as compared to equimolar glycidol, respectively. Following a single administration of glycidol-related compounds to ICR mice, diHOPrVal formation was observed only in the epichlorohydrin-treated group after day 5 of exposure. After 14 days of repeated dosing, the amounts of diHOPrVal produced by epichlorohydrin and 3-MCPD invivo were <1% of diHOPrVal produced by an equal molar concentration of glycidol. Furthermore, glyceraldehyde group produced 0.2% of diHOPrVal at the same molar concentration of glycidol equivalents, in which diHOPrVal formation could not be confirmed by the invitro assay. The results indicate the usefulness of diHOPrVal as an exposure marker for glycidol; however, the contribution of its formation invivo by exposure to various chemicals will be necessary to validate and interpret the results.

Carcinogenic Effects of Nitrosodimethylamine (NDMA) Contamination in Ranitidine: Defining the Relationship With Renal Malignancies

Purpose: Ranitidine, a medication used to treat gastric ulcers and reflux, was once the highest selling drug in the world with over $1 billion in annual sales. However, in 2020, ranitidine, known more commonly by the brand name Zantac, virtually vanished from the market after multiple regulatory bodies including the US Food and Drug Administration recommended withdrawal. Their concern was based on detection of nitrosodimethylamine (NDMA), a known animal carcinogen, in ranitidine samples. NDMA has been shown to induce multiple tumor types, including renal tumors. The effects of human exposure, however, are not completely understood. This review aims to clarify what is known about NDMA contamination in ranitidine, the carcinogenic mechanisms of NDMA, and possible associations between ranitidine consumption and renal cancers. Materials and Methods: A comprehensive literature review was performed regarding ranitidine and NDMA, carcinogenesis, and associations with malignancy. Data were considered from environmental, preclinical, and clinical studies from various disciplines. Publications from governmental bodies, including the Food and Drug Administration and International Agency for Research on Cancer, were reviewed and included for analysis. Results: Multiple preclinical studies have demonstrated the carcinogenic effects of NDMA in animals with high rates of renal tumor development. NDMA has been detected in industrial, dietary, and pharmacologic sources. Regarding NDMA levels in ranitidine, evidence points to associations with storage conditions at elevated temperatures and/or prolonged duration as well as endogenous production facilitated by physiologic gastric conditions. Once metabolized, NDMA by-products form DNA adducts with established roles in carcinogenesis. Human data on ranitidine consumption and cancer development are derived from large population studies limited by their observational nature and inconsistent measure of NDMA exposure. To date, NDMA associations with renal malignancies—although evident in animal studies—is not clearly delineated in humans. Conclusions: Detection of NDMA in ranitidine has prompted governmental regulatory bodies to recommend withdrawal of ranitidine from US markets. Classification of NDMA as a “probable human carcinogen” is based on decades of animal studies with a notable rate of renal malignancies. Human observational studies do not clearly demonstrate an association with renal malignancies, but the available data have significant limitations and any conclusions drawn from these observational studies, whether supporting or challenging associations between ranitidine use and renal cancer, should be interpreted with caution.

Lifetime exposure to brominated trihalomethanes in drinking water and swimming pool attendance are associated with chronic lymphocytic leukemia: a Multicase-Control Study in Spain (MCC-Spain)

BackgroundChronic lymphocytic leukemia (CLL) etiology is poorly understood, and carcinogenic chemicals in drinking and recreational water are candidates.ObjectiveTo evaluate the association between drinking-water exposure to trihalomethanes (THMs) and nitrate as well as lifetime swimming pool attendance and CLL.MethodsDuring 2010–2013, hospital-based CLL cases and population-based controls were recruited in Spain, providing information on residential histories, type of water consumed and swimming pool attendance. Average THMs and nitrate levels in drinking water were linked to lifetime water consumption. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using mixed models.ResultsFinal samples for residential tap water analyses and swimming pool attendance analyses were 144 cases/1230 controls and 157 cases/1240 controls, respectively. Mean (SD) values for average lifetime residential brominated THMs and chloroform in tap water (μg/L), and ingested nitrate (mg/day) were 48.1 (35.6), 18.5 (6.7) and 13.7 (9.6) respectively in controls; and 72.9 (40.7), 17.9 (5.4), and 14.1 (8.8) in CLL cases. For each 10 μg/L increase of brominated THMs and chloroform lifetime-average levels, the ORs (95% CI) were 1.22 (1.14, 1.31) and 0.54 (0.34, 0.87), respectively. For each 5 mg/day increase of ingested nitrate, the OR of CLL was 0.91 (0.80, 1.04). The OR of lifetime pool users (vs. non-users) was 2.38 (1.61, 3.52). Upon performing annual frequency of attending pools analysis through categorization, the second and third categories showed an ORs of 2.36 (1.49, 3.72) and 2.40 (1.51, 3.83), respectively, and P-trend of 0.001.Impact statementThis study identifies an association of long-term exposure to THMs in drinking water, at concentrations below the regulatory thresholds and WHO guidelines, and swimming pool attendance, with chronic lymphocytic leukemia (CLL). These unprecedented findings are highly relevant since CLL is an incurable cancer with still unknown etiology and because the widespread exposure to chlorination by-products that remain in drinking and recreational water worldwide. Despite the demonstrated carcinogenicity in animals of several chlorination by-products, little is known about their potential risks on human health. This study makes a significant contribution to the search for environmental factors involved in the etiology of CLL and to the evidence of the health impact of these high prevalent water contaminants.

Computational Prediction of Metabolic α-Carbon Hydroxylation Potential of N-Nitrosamines: Overcoming Data Limitations for Carcinogenicity Assessment.

Recent withdrawal of several drugs from the market due to elevated levels of N-nitrosamine impurities underscores the need for computational approaches to assess the carcinogenicity risk of nitrosamines. However, current approaches are limited because robust animal carcinogenicity data are only available for a few simple nitrosamines, which do not represent the structural diversity of the many possible nitrosamine drug substance related impurities (NDSRIs). In this paper, we present a novel method that uses data on CYP-mediated metabolic hydroxylation of CH2 groups in non-nitrosamine xenobiotics to identify structural features that may also help in predicting the likelihood of metabolic α-carbon hydroxylation in N-nitrosamines. Our approach offers a new avenue for tapping into potentially large experimental data sets on xenobiotic metabolism to improve risk assessment of nitrosamines. As α-carbon hydroxylation is the crucial rate-limiting step in nitrosamine metabolic activation, identifying and quantifying the influence of various structural features on this step can provide valuable insights into their carcinogenic potential. This is especially important considering the scarce information available on factors that affect NDSRI metabolic activation. We have identified hundreds of structural features and calculated their impact on hydroxylation, a significant advancement compared to the limited findings from the small nitrosamine carcinogenicity data set. While relying solely on α-carbon hydroxylation prediction is insufficient for forecasting carcinogenic potency, the identified features can help in the selection of relevant structural analogues in read across studies and assist experts who, after considering other factors such as the reactivity of the resulting electrophilic diazonium species, can establish the acceptable intake (AI) limits for nitrosamine impurities.

Acceptable intakes (AIs) for 11 small molecule N-nitrosamines (NAs)

Low levels of N-nitrosamines (NAs) were detected in pharmaceuticals and, as a result, health authorities (HAs) have published acceptable intakes (AIs) in pharmaceuticals to limit potential carcinogenic risk. The rationales behind the AIs have not been provided to understand the process for selecting a TD50 or read-across analog. In this manuscript we evaluated the toxicity data for eleven common NAs in a comprehensive and transparent process consistent with ICH M7. This evaluation included substances which had datasets that were robust, limited but sufficient, and substances with insufficient experimental animal carcinogenicity data. In the case of robust or limited but sufficient carcinogenicity information, AIs were calculated based on published or derived TD50s from the most sensitive organ site. In the case of insufficient carcinogenicity information, available carcinogenicity data and structure activity relationships (SARs) were applied to categorical-based AIs of 1500 ng/day, 150 ng/day or 18 ng/day; however additional data (such as biological or additional computational modelling) could inform an alternative AI. This approach advances the methodology used to derive AIs for NAs.

Degradation of Aflatoxin B1 in Moldy Maize by Pseudomonas aeruginosa and Safety Evaluation of the Degradation Products

Aflatoxin B1 (AFB1) is the most harmful mycotoxin commonly found in food and feed. Pollution from AFB1 causes serious economic and health issues worldwide because it causes strong mutagenicity and carcinogenicity in humans and animals. In this study, Pseudomonas aeruginosa was used to degrade AFB1 in moldy maize, and the safety of this biological method was investigated using genotoxicity and cytotoxicity tests. Using response surface methodology, we established the optimal conditions for degrading AFB1 by the fermentation supernatant of P. aeruginosa. Under these conditions, the degradation rate of AFB1 reached 99.67%. Furthermore, the Ames mutagenicity test showed that AFB1 treated with P. aeruginosa fermentation supernatant for 72 h was not mutagenic. CCK-8 cell assay showed that AFB1 cytotoxicity was significantly reduced after degradation. Overall, our findings show that the fermentation supernatant of P. aeruginosa may be a good candidate for biodegradation of AFB1.

Potential Role of Lipase Activity on the Internal Exposure Assessment of Glycidol Released from Its Fatty Acid Esters.

Glycidyl fatty acid esters (GEs) can be found in food, and they can be converted into genotoxic animal carcinogen glycidol in vivo by the action of lipase. This study examined whether human ingestion of charbroiled pork containing high levels of GEs (300 µg/day) increased glycidol-hemoglobin adduct (diHOPrVal), a marker of internal exposure to glycidol using LC-MS/MS. Contrary to expectation, the diHOPrVal value before ingesting charbroiled pork was 3.11 ± 1.10 pmol/g globin, which slightly decreased to 2.48 ± 0.47 pmol/g globin after 5 days of consumption. The decrease in lipase activity caused by the continuous consumption of lipid-rich foods such as meat in humans might decrease internal exposure to glycidol released from its esters. Thus, lipase activity was measured in C57/BL6J mice fed a high-fat diet (HFD) for 8 weeks, and diHOPrVal formation was measured after the administration of glycidyl oleate. Lipase activity was significantly lower in the HFD group than in the normal diet group. The amount of diHOPrVal was reduced in the HFD group. Therefore, the lipase activity was reduced by HFD, thereby decreasing the degradation of glycidol from glycidyl oleate. These results indicate that changes in lipase activity depending on the amount of lipids in the diet may affect the assessment of GEs exposure, and monitoring the lipase activity would provide a comprehensive understanding of exposure assessment.

Development of physiologically based toxicokinetic models for 3-monochloropropane-1,2-diol and glycidol.

3-Monochloropropane-1,2-diol (3-MCPD), glycidol, together with their fatty acid esters are commonly presented in various food and have shown carcinogenicity in various laboratory animals. Public health risk assessment of 3-MPCD and glycidol exposure relies on quantitative tools that represent their in vivo toxicokinetics. In order to better understand the absorption, distribution, metabolism, and excretion profiles of 3-MCPD and glycidol in male rats, a physiologically based pharmacokinetic (PBTK) model was developed. The model's predictive power was evaluated by comparing in silico simulations to in vivo time course data obtained from experimental studies. Results indicate that our PBTK model successfully captured the toxicokinetics of both free chemicals in key organs, and their metabolites in accessible biological fluids. With the validated PBTK model, we then gave an animal-free example on how to extrapolate the toxicological knowledge acquired from a single gavage to a realistic dietary intake scenario. Three biomarkers, free compound in serum, urinary metabolite DHPMA, and glycidol-hemoglobin adduct (diHOPrVal) were selected for in silico simulation following constant dietary intakes, and their internal levels were correlated with proposed external daily exposure via reverse dosimetry approaches. Taken together, our model provides a computational approach for extrapolating animal toxicokinetic experiments to biomonitoring measurement and risk assessment.

Hydroquinone triggers pyroptosis and endoplasmic reticulum stress via AhR-regulated oxidative stress in human lymphocytes

Benzene is a frequent component of environmental pollution and is abundant in petrochemicals, decorative materials, motor vehicle exhaust and cigarette smoke. Benzene is a well-known carcinogen in humans and animals, but the molecular mechanism has not yet been elucidated. Our earlier research indicated that hydroquinone (HQ), one of the main reactive metabolites of benzene, could activate aryl hydrocarbon receptor (AhR), which is essential for HQ-induced toxicity, including apoptosis and DNA damage. Since AhR is an important regulator of the immune system that integrates the environmental stimulus and immune response, we examined whether and how HQ-induced AhR activity could lead to NLRP3 inflammasome-dependent pyroptosis in JHP cells. Our results showed that HQ could cause inflammation process and resultant pyroptosis. In JHP cells, HQ also induced endoplasmic reticulum stress (ERS) by releasing excessive reactive oxygen species (ROS). The activation of pyroptosis induced by HQ treatment was reversed by an antioxidant (NAC) and an ERS inhibitor (4-PBA). Interestingly, the treatment of CH223191, an AhR inhibitor, reversed HQ-induced oxidative stress, ERS and pyroptosis. These data suggested that AhR-mediated HQ-induced ERS, ROS and inflammasome activation may play vital roles in the toxic effects of benzene. This work provides insights and prospective strategies into potential mechanisms for reducing benzene-induced hematotoxicity.