Carcinogenicity of glycidamide in B6C3F1 mice and F344/N rats from a two-year drinking water exposure

A Comprehensive Bibliometric Study in the Context of Chemical Hazards in Coffee

The research aimed to carefully review the chemical hazards linked to the coffee production chain to analyse the risks and opportunities for consumers and the environment, as well as identify potential knowledge gaps. The Scopus database was consulted from 1949 to April 2024 to conduct a bibliometric analysis. As a result, 680 articles were analysed. Results indicated a significant increase in research activity since 2015. China, Brazil, and the USA were the leading countries in scientific production and collaborations. The most prolific journals in this field were Chemosphere, Science of the Total Environment, Food Chemistry, Journal of Agricultural and Food Chemistry, and Journal of Environmental Management, all of which are in the first quartile. The word analysis revealed two main themes: the first focuses on the chemical hazards of coffee and their impact on health, while the second explores the waste generated during coffee production and its potential for reuse. The topics covered in the research include the composition of coffee, associated chemical hazards, possible health risks, and ways to reuse waste for environmental protection. Future research should concentrate on optimising techniques and processes to ensure quality, safety, and sustainability.

Obesity Induces DNA Damage in Mammary Epithelial Cells Exacerbated by Acrylamide Treatment through CYP2E1-Mediated Oxidative Stress

Obesity and environmental toxins are risk factors for breast cancer; however, there is limited knowledge on how these risk factors interact to promote breast cancer. Acrylamide, a probable carcinogen and obesogen, is a by-product in foods prevalent in the obesity-inducing Western diet. Acrylamide is metabolized by cytochrome P450 2E1 (CYP2E1) to the genotoxic epoxide, glycidamide, and is associated with an increased risk for breast cancer. To investigate how acrylamide and obesity interact to increase breast cancer risk, female mice were fed a low-fat (LFD) or high-fat diet (HFD) and control water or water supplemented with acrylamide at levels similar to the average daily exposure in humans. While HFD significantly enhanced weight gain in mice, the addition of acrylamide did not significantly alter body weights compared to respective controls. Mammary epithelial cells from obese, acrylamide-treated mice had increased DNA strand breaks and oxidative DNA damage compared to all other groups. In vitro, glycidamide-treated COMMA-D cells showed significantly increased DNA strand breaks, while acrylamide-treated cells demonstrated significantly higher levels of intracellular reactive oxygen species. The knockdown of CYP2E1 rescued the acrylamide-induced oxidative stress. These studies suggest that long-term acrylamide exposure through foods common in the Western diet may enhance DNA damage and the CYP2E1-induced generation of oxidative stress in mammary epithelial cells, potentially enhancing obesity-induced breast cancer risk.

Estimation of intake and quantification of hemoglobin adducts of acrylamide in adolescents in Sweden

Blood samples (n = 600) from participants in the Swedish dietary survey Riksmaten Adolescents 2016-17 were analyzed with respect to hemoglobin (Hb) adducts from acrylamide (AA) and its metabolite glycidamide (GA) as biomarkers of internal dose/exposure. The results are presented from statistical analyses of food consumption data (2-day dietary recall and questionnaires) and measured Hb adduct levels. The estimated exposure as well as consumption data were examined in relation to non-dietary factors such as sex, age (group medians of 12, 15, and 18 years), place of residence (urban/rural), smoking status, and parental education level. The median AA adduct level was estimated to be 34 pmol/g Hb (range 14-225). No significant difference was found for place of residence, parental education, sex, or age. A significant difference was found between the median adduct levels of daily smokers (n = 8) and never smokers (n = 323) in the older age groups, but not between occasional smokers (n = 47) and never smokers. The median differences between daily smokers and never smokers were 76, 40, and 128 pmol/g Hb for AA, GA, and AA + GA, respectively. The median AA intake for the whole group of adolescents, as estimated from dietary recall data combined with reported concentrations in food, was 0.40 μg/kg bw/day. The corresponding median intake estimated from measured Hb adduct levels of AA was 0.20 μg/kg bw/day. A significant, although low, positive Spearman correlation was found between the two intake estimates (p-value = 8 × 10-3; ρ = 0.11). From the estimated intake of AA from food frequency questionnaires, significance was found for the 15-year-old children with higher AA adduct levels observed at higher consumption frequencies of fried potatoes/French fries. AA is considered a genotoxic carcinogen. For the estimated intake of AA for any age group and method (dietary recall or AA adduct), both a calculated margin of exposure as well as lifetime quantitative cancer risk estimates indicate health concern. A future study on food consumption designed with respect to AA exposure would provide a better understanding of the correlation between consumption and exposure and should give a more reliable estimate of the contribution of dietary AA to the overall cancer risk.

Two decades of research in dietary acrylamide: What do we know today

After nearly two decades since acrylamide was first raised as a potential safety issue in foods, significant progress has been made in understanding its formation during cooking, how to reduce levels in the most concerned foods, and the possible cancer risk to humans. Despite the huge wealth of knowledge gathered on this topic over the past years, a few new discoveries in occurrence, mitigation, analysis and risk assessment are worthy to note. This short review highlights the salient novelties pertaining to acrylamide, particularly in the areas of formation & analysis, existing and possible future regulations in the European Union, and finally considerations that may lead to possibly revisiting the toxicity of acrylamide and the main metabolite, glycidamide.

Dietary intake of acrylamide in the Norwegian EuroMix biomonitoring study: Comparing probabilistic dietary estimates with haemoglobin adduct measurements

Acrylamide is a probable human carcinogen with widespread exposure via food. The present study compared acrylamide intake measurements obtained from haemoglobin adduct levels and self-registered dietary consumption data in a group of 144 Norwegian healthy adults. Acrylamide adducts to N-terminal valine in haemoglobin were measured and used to estimate the intake via the internal dose approach which showed a median (interquartile range) of 0.24 (0.19-0.30) μg/kg bw/day. Data from weighed food records and food frequency questionnaires from the same individuals were used for probabilistic modelling of the intake of acrylamide. The median acrylamide intake was calculated to be 0.26 (0.16-0.39) and 0.30 (0.23-0.39) μg/kg bw/day, respectively from the two sources of self-registered dietary consumption data. Overall, a relatively good agreement was observed between the methods in pairwise comparison in Bland-Altman plots, with the methods disagreeing with 7% or less of the values. The intake estimates obtained with the two dietary consumption methods and one biomarker method are in line with earlier dietary estimates in the Norwegian population. The Margin of Exposure indicate a possible health risk concern from dietary acrylamide. This is the first study with a comparison in the same individuals of acrylamide intake estimates obtained with these methods.

Therapeutic role of melatonin on acrylamide-induced hepatotoxicity in pinealectomized rats: Effects on oxidative stress, NF-κB signaling pathway, and hepatocellular proliferation

Acrylamide (AA) is formed in some foods by the cooking process at high temperatures, and it could be a carcinogen in humans and rodents. The purpose of the current study was to reveal the possible protective effects of melatonin against AA-induced hepatic oxidative stress, hepatic inflammation, and hepatocellular proliferation in pinealectomized rats. Hence, the sham and pinealectomized rats were consecutively given AA alone (25 mg/kg) or with melatonin (10 mg/kg) for 21 days. Melatonin acts as an antioxidant, anti-inflammatory, and antiapoptotic agent and introduces as a therapeutic strategy for AA-induced hepatotoxicity. Melatonin supplementation reduced AA-caused liver damage by decreasing the serum AST, ALT, and ALP levels. Melatonin raised the activities of SOD and CAT and levels of GSH and suppressed hepatic inflammation (TNF-α) and hepatic oxidative stress in liver tissues. Moreover, histopathological alterations and the disturbances in immunohistochemical expression of NF-κB and Ki67 were improved after melatonin treatment in AA-induced hepatotoxicity. Overall, our results demonstrate that melatonin supplementation exhibits adequate hepatoprotective effects against hepatotoxicity of AA on pinealectomized rat liver architecture and the tissue function through the equilibration of oxidant/antioxidant status, the regulation of cell proliferation and the suppression of the release of proinflammatory cytokines.

Urinary metabolites of multiple volatile organic compounds among pregnant women across pregnancy: Variability, exposure characteristics, and associations with selected oxidative stress biomarkers

Volatile organic compounds (VOCs) are a group of pollutants pervasive in daily life with identified adverse health effects. However, no study has investigated the variability in VOC metabolites during pregnancy and their relationships with oxidative stress biomarkers in pregnant women. In the present study, the variability of 21 selected VOC metabolites was examined and their relationships with three selected oxidative stress biomarkers measured in spot urine samples at three trimesters of 1094 pregnant women were analyzed. Nineteen VOC metabolites were ubiquitous in the urine samples with detection rates ranging from 75.9% to 100%. Monohydroxybutenyl mercapturic acid (MHBMA) and s-phenyl mercapturic acid (PMA) had detection rates lower than 1.00%. Intraclass correlation coefficients (ICCs) of the detected analytes at three trimesters ranged 0.07-0.24, and the concentrations were highest in the first trimester. Higher concentrations of some VOC metabolites were related with participant characteristics including higher pre-pregnancy body mass index (BMI), lower education level, unemployment during pregnancy, multiparity, and sampling season of summer or winter. In repeated cross-sectional analyses, interquartile range (IQR) increases in the 19 detected VOC metabolites were positively related with 8-hydroxy-2'-deoxyguanosine (8-OHdG), 8-hydroxyguanosine (8-OHG), and 4-hydroxy nonenal mercapturic acid (HNEMA) with the estimates ranging from 9.00% to 204%. The mixture effect of the VOC metabolites on the oxidative stress biomarkers was further assessed using weighted quantile sum regression (WQS) models and the results showed that the WQS index of VOC metabolite mixture was significantly associated with 8-OHdG (β: 0.37, 0,32, and 0.39 at the 1st, 2nd, and 3rd trimester, respectively), 8-OHG (0.38, 0.32, and 0.39) and HNEMA (1.21, 1.08, and 1.10). Glycidamide mercapturic acid (GAMA), and trans,trans-muconic acid (MU) were the strongest contributors of the mixture effect on 8-OHdG, 8-OHG, and HNEMA, respectively. Overall, urinary concentrations of the VOC metabolites during pregnancy were strongly associated with the oxidative stress biomarkers.

Metabolomics strategy comprehensively unveils the effect of catechins intervention on the biomarkers of exposure to acrylamide and biomarkers of cardiometabolic risk

Polyphenolic antioxidants have been suggested to control the generation of acrylamide during thermal reactions. However, their role in protecting against the toxicity of acrylamide and the mechanism of action regarding profile alteration of biomarkers and metabolome remains unclear. A total of 65 adults were randomized into tea polyphenols (TP) and control groups and served with potato chips, which corresponded to an intake level of 12.6 μg/kg·bw of acrylamide, followed by capsules containing 200 mg, 100 mg or 50 mg TP, or equivalent placebo. Moreover, nontargeted urinary metabolomics analysis in acrylamide exposed rats was conducted using ultra-high performance liquid chromatography linked with a quadrupole-orbitrap high-resolution mass spectrometry. Our results showed that supplementation with catechins promoted the excretion of N-acetyl-S-(2-carbamoyl-2-hydroxyethyl)-l-cysteine in both humans and rats. We also found that epigallocatechin gallate (EGCG) or epicatechin (EC) intervention attenuated the ratio of hemoglobin adduct of glycidamide to hemoglobin adduct of acrylamide in rat blood. Metabolomics analysis revealed that EGCG/EC intervention regulated the differential expressed metabolites, including l-glutamic acid, 2-oxoglutarate, citric acid, and cysteinylglycine. Kyoto Encyclopedia of Genes and Genomes pathway analysis further showed acrylamide-induced metabolic disorders were improved after EGCG/EC supplementation by glycolipid metabolism (alanine, aspartate and glutamate metabolism, and d-Glutamine and d-glutamate metabolism) and energy metabolism (tricarboxylic acid cycle). Notably, the supplement use of EGCG prevented the cardiometabolic risk after exposure to acrylamide by mediating the phenylalanine and hippuric acid in phenylalanine metabolism. Here we showed the beneficial effect of catechins as major polyphenolic antioxidant ingredients on the toxicity of acrylamide by the changes in biomarkers from metabolic profile analysis based on human and animal studies. These findings shed light into the catechins as natural polyphenolic antioxidants that could be a therapeutic ingredient for preventing acrylamide-induced cardiometabolic toxicity.

The association between biomarkers of acrylamide and cancer mortality in U.S. adult population: Evidence from NHANES 2003-2014

The association between acrylamide (AA) and the development of cancer has been extensively discussed but the results remained controversial, especially in population studies. Large prospective epidemiological studies on the relationship of AA exposure with cancer mortality were still lacking. Therefore, we aimed to assess the association between AA biomarkers and cancer mortality in adult population from National Health and Nutrition Examination Survey (NHANES) 2003-2014. We followed 3717 participants for an average of 10.3 years. Cox regression models with multivariable adjustments were performed to determine the relationship of acrylamide hemoglobin adduct (HbAA) and glycidamide hemoglobin adduct (HbGA) with cancer mortality. Mediation analysis was conducted to demonstrate the mediated role of low-grade inflammation score (INFLA-score) in this correlation. Compared with the lowest quintile, participants with the highest quintile of HbAA, HbGA and HbAA+HbGA had increased cancer mortality risk, and the hazard ratios(HRs) were 2.07 (95%CI:1.04-4.14) for HbAA, 2.39 (95%CI:1.29-4.43) for HbGA and 2.48 (95%CI:1.28-4.80) for HbAA+HbGA, respectively. And there was a considerable non-linearity association between HbAA and cancer mortality (pfor non-linearity = 0.0139). We further found that increased INFLA-score significantly mediated 71.67% in the effect of HbGA exposure on increased cancer mortality risk. This study demonstrates that hemoglobin biomarkers of AA are positively associated with cancer mortality in adult American population and INFLA-score plays a mediated role in this process. Our findings can raise public awareness of environmental and dietary exposure to acrylamide and remind people to refrain from smoking or having acrylamide-rich foods.

Dietary Habits and Daily Routines as Prognostic Factors in Endometrial Cancer: A Machine Learning Approach

Endometrial cancer (EC) is becoming more common worldwide, primarily due to an increase in life expectancy and obesity. As several modifiable factors may affect EC incidence and progression, we aimed to elucidate how dietary habits and daily routines influence recurrence and survival among women with EC, using a Random Survival Forest (RSF) approach. 481 women who previously underwent hysterectomy due to EC completed two extensive questionnaires on dietary habits and daily routines, and we used RSF to identify risky or protective variables. Among the 186 variables considered, consumption of sugar-sweetened beverages and fried potatoes increased the risk of EC recurrence and death, while physical activity decreased the risk of death. We conclude that RSF is a suitable approach to study survival in multivariable datasets.

Glycidamide and cis-2-butene-1,4-dial (BDA) as potential carcinogens and promoters of liver cancer - An in vitro study

Acrylamide and furan are environmental and food contaminants that are metabolized by cytochrome P450 2E1 (CYP2E1), giving rise to glycidamide and cis-2-butene-1,4-dial (BDA) metabolites, respectively. Both glycidamide and BDA are electrophilic species that react with nucleophilic groups, being able to introduce mutations in DNA and perform epigenetic remodeling. However, whereas these carcinogens are primarily metabolized in the liver, the carcinogenic potential of acrylamide and furan in this organ is still controversial, based on findings from experimental animal studies. With the ultimate goal of providing further insights into this issue, we explored in vitro, using a hepatocyte cell line and a hepatocellular carcinoma cell line, the putative effect of these metabolites as carcinogens and cancer promoters. Molecular alterations were investigated in cells that survive glycidamide and BDA toxicity. We observed that those cells express CD133 stemness marker, present a high proliferative capacity and display an adjusted expression profile of genes encoding enzymes involved in oxidative stress control, such as GCL-C, GSTP1, GSTA3 and CAT. These molecular changes seem to be underlined, at least in part, by epigenetic remodeling involving histone deacetylases (HDACs). Although more studies are needed, here we present more insights towards the carcinogenic capacity of glycidamide and BDA and also point out their effect in favoring hepatocellular carcinoma progression.

Dietary Acrylamide Exposure and Risk of Site-Specific Cancer: A Systematic Review and Dose-Response Meta-Analysis of Epidemiological Studies

Diet is a main source of acrylamide exposure to humans. Existing observational data on the relationship between dietary exposure to acrylamide and risk of cancer are inconsistent. We performed a systematic review and dose-response meta-analysis of epidemiological studies evaluating the association between dietary acrylamide exposure and several site-specific cancer. A systematic literature search was conducted in PubMed, Scopus, and Web of Science databases until March 7, 2022. Studies were eligible if they were carried out in non-occupationally exposed adults, assessed dietary acrylamide exposure (μg/day) and reported risk estimates of cancer incidence (all but gynecological cancers). Using a random-effects model, we performed a meta-analysis of site-specific cancer risk comparing the highest vs. lowest category of dietary acrylamide exposure. We also carried out a one-stage dose-response meta-analysis assessing the shape of the association. Out of 1,994 papers screened, 31 were eligible (total of 16 studies), which included 1,151,189 participants in total, out of whom 48,175 developed cancer during the median follow-up period of 14.9 years (range 7.3–33.9). The mean estimated dose of dietary acrylamide across studies was 23 μg/day. Pooled analysis showed no association between the highest vs. lowest dietary acrylamide exposure and each site-specific cancer investigated, with no evidence of thresholds in the dose-response meta-analysis. There were also no associations between dietary acrylamide exposure and the risk of cancers when stratifying by smoking status, except for increased risk of lung cancer in smokers. In conclusion, high dietary acrylamide exposure was not associated with an increased risk of site-specific non-gynecological cancer.

Acrylamide in widely consumed foods - a review

Acrylamide (AA) is considered genotoxic, neurotoxic and a 'probable human carcinogen'. It is included in group 2 A of the International Agency for Research on Cancer (IARC). The formation of AA occurs when starch-based foods are subjected to temperatures higher than 120 °C in an atmosphere with very low water content. The aim of this review is to shed light on the toxicological aspects of AA, showing its regulatory evolution, and describing the most interesting mitigation techniques for each food category involved, with a focus on compliance with EU legislation in the various classes of consumer products of industrial origin in Europe.

Mechanism of reactive oxygen species generation and oxidative DNA damage induced by acrylohydroxamic acid, a putative metabolite of acrylamide

Acrylamide is formed during the heating of food and is also found in cigarette smoke. It is classified by the International Agency for Research on Cancer as a probable human carcinogen (Group 2A). Glycidamide, an epoxide metabolite of acrylamide, is implicated in the mechanism of acrylamide carcinogenicity. Acrylamide causes oxidative DNA damage in target organs. We sought to clarify the mechanism of acrylamide-induced oxidative DNA damage by investigating site-specific DNA damage and reactive oxygen species (ROS) generation by a putative metabolite of acrylamide, acrylohydroxamic acid (AA). Our results, using ³²P-5'-end-labeled DNA fragments, indicated that, although AA alone did not damage DNA, AA treated with amidase induced DNA damage in the presence of Cu(II). DNA cleavage occurred preferentially at T and C, and particularly at T in 5'-TG-3' sequences, and the DNA cleavage pattern was similar to that of hydroxylamine. The DNA damage was inhibited by methional, catalase, and Cu(I)-chelator bathocuproine, suggesting that H₂O₂ and Cu(I) are involved in the mechanism of DNA damage induced by AA treated with amidase. In addition, amidase-treated AA increased 8-oxo-7,8-dihydro-2'-deoxyguanosine formation in calf thymus DNA, an indicator of oxidative DNA damage, in a dose-dependent manner. In conclusion, hydroxylamine, possibly produced from AA treated with amidase, was autoxidized via the Cu(II)/Cu(I) redox cycle and H₂O₂ generation, suggesting that oxidative DNA damage induced by ROS plays an important role in acrylamide-related carcinogenesis.

Simultaneous toxicokinetics characterization of acrylamide and its primary metabolites using a novel microdialysis isotope-dilution liquid chromatography mass spectrometry method

Acrylamide (AA) is a toxicant in high-temperature processed foods and an animal carcinogen. Upon absorption, AA is metabolized to glycidamide (GA) or conjugates with glutathione (AA-GSH). Important advantages of microdialysis coupled with liquid chromatography-tandem mass spectrometry (MD-LC-MS/MS) include its minimization of potential losses during sample collection, storage and preparation, as well as an improvement in temporal resolution for toxicokinetics (TKs). We aimed to simultaneously study the TKs of AA and products of its primary metabolism using an isotope-dilution (ID) MD-LC-MS/MS method. MD probes implanted into the jugular vein/right atrium of anesthetized Sprague Dawley rats were connected to the ID-LC-MS/MS for continuous monitoring of AA, GA and AA-GSH in the blood every 15 min over 8 h following intraperitoneal AA administration (0.1 mg/kg or 5 mg/kg). AA, GA, and AA-GSH TKs followed linear kinetics: GA AUC/AA AUC = 0.11 and AA-GSH AUC/AA AUC = 0.011 at 5 mg/kg. Elimination half-life (T_e1/2) values were 2.44 ± 0.70, 4.93 ± 2.37 and 3.47 ± 1.47 h for AA, GA and AA-GSH, respectively. GA TKs reached a plateau at 3-6 h, suggesting that metabolic saturation of AA and T_e1/2 values of the analytes were prolonged with AA at 5 mg/kg. Our results demonstrate that oxidation of AA to GA overwhelmed the conjugation of AA with GSH. Our innovative MD-ID-LC-MS/MS method facilitates the simultaneous characterization of multiple TKs associated with toxicants and their active metabolites with excellent temporal resolution to capture metabolic saturation of AA to GA.

Comprehensive profile of DNA adducts as both tissue and urinary biomarkers of exposure to acrylamide and chemo-preventive effect of catechins in rats

Two representative DNA adducts from acrylamide exposure, N7-(2-carbamoyl-2-hydroxyethyl) guanine (N7-GA-Gua) and N3-(2-carbamoyl-2-hydroxyethyl) adenine (N3-GA-Ade), are important long-term exposure biomarkers for evaluating genotoxicity of acrylamide. Catechins as natural antioxidants present in tea possess multiple health benefits, and may also have the potential to protect against acrylamide-induced DNA damage. The current study developed an ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method for simultaneous analysis of N7-GA-Gua and N3-GA-Ade in tissues and urine. The validated UHPLC-MS/MS method showed high sensitivity, with limit of detection and limit of quantification ranging 0.2-0.8 and 0.5-1.5 ng/mL, respectively, and achieved qualified precision (RSD<14.0%) and spiking recovery (87.2%-110.0%) with elution within 6 min, which was suitable for the analysis of the two DNA adducts in different matrices. The levels of N7-GA-Gua and N3-GA-Ade ranged 0.9-11.9 and 0.6-3.5 μg/g creatinine in human urine samples, respectively. To investigate the interventional effects of catechins on the two DNA adducts from acrylamide exposure, rats were supplemented with three types of catechins (tea polyphenols, epigallocatechin gallate, and epicatechin) 30 min before administration with acrylamide. Our results showed that catechins effectively inhibited the formation of DNA adducts from acrylamide exposure in both urine and tissues of rats. Among three catechins, epicatechin performed the best inhibitory effect. The current study provided evidence for the chemo-preventive effect of catechins, indicating that dietary supplement of catechins may contribute to health protection against exposure to acrylamide.

Mutagenicity of acrylamide and glycidamide in human TP53 knock-in (Hupki) mouse embryo fibroblasts

Acrylamide is a suspected human carcinogen formed during high-temperature cooking of starch-rich foods. It is metabolised by cytochrome P450 2E1 to its reactive metabolite glycidamide, which forms pre-mutagenic DNA adducts. Using the human TP53 knock-in (Hupki) mouse embryo fibroblasts (HUFs) immortalisation assay (HIMA), acrylamide- and glycidamide-induced mutagenesis was studied in the tumour suppressor gene TP53. Selected immortalised HUF clones were also subjected to next-generation sequencing to determine mutations across the whole genome. The TP53-mutant frequency after glycidamide exposure (1.1 mM for 24 h, n = 198) was 9% compared with 0% in cultures treated with acrylamide [1.5 (n = 24) or 3 mM (n = 6) for 48 h] and untreated vehicle (water) controls (n = 36). Most glycidamide-induced mutations occurred at adenines with A > T/T > A and A > G/T > C mutations being the most common types. Mutations induced by glycidamide occurred at specific TP53 codons that have also been found to be mutated in human tumours (i.e., breast, ovary, colorectal, and lung) previously associated with acrylamide exposure. The spectrum of TP53 mutations was further reflected by the mutations detected by whole-genome sequencing (WGS) and a distinct WGS mutational signature was found in HUF clones treated with glycidamide that was again characterised by A > G/T > C and A > T/T > A mutations. The WGS mutational signature showed similarities with COSMIC mutational signatures SBS3 and 25 previously found in human tumours (e.g., breast and ovary), while the adenine component was similar to COSMIC SBS4 found mostly in smokers’ lung cancer. In contrast, in acrylamide-treated HUF clones, only culture-related background WGS mutational signatures were observed. In summary, the results of the present study suggest that glycidamide may be involved in the development of breast, ovarian, and lung cancer.

Acrylamide impairs ovarian function by promoting apoptosis and affecting reproductive hormone release, steroidogenesis and autophagy-related genes: An in vivo study

Acrylamide (ACR) toxicity is quite common due to its widespread use in industry and due to the Maillard browning reaction that occurs in foods containing high concentrations of hydrocarbons subjected to high temperatures. This study aimed to elucidate the female reproductive toxicity of ACR in vivo. Fifty-day-old Wistar-Albino female rats were treated with different dosages of ACR (2.5, 10, and 50 mg/kg/day). After treatment, the animals were sacrificed, and serum and ovary samples were collected for histological examination, hormone analysis, TUNEL analysis, and RT-PCR studies. We found that ACR acts by significantly reducing ovarian weight and serum progesterone and estradiol concentrations. In addition, ACR treatment led to pyknotic, heterochromatic characteristics and nuclear fragmentation, as evidenced by hematoxylin staining. The TUNEL assay revealed that granulosa cells were affected after the oral administration of ACR, leading to the apoptosis of follicles at different stages of growth. Compared with the control condition, high doses of ACR (50 mg/kg/day) significantly induced the overexpression of INSL3, CYP17a, IGF1, ESR1, ESR2, ATG5, ATG12 and LC3 in the ovary. Moreover, LC3 mRNA levels significantly increased with increasing doses of ACR (2.5, 10 and 50 mg/kg/day), suggesting that ACR treatment induced autophagy. In conclusion, ACR induced ovarian dysfunction by affecting steroid hormone release, increasing apoptosis and mRNA levels of autophagy-related genes. The eventual correlation between apoptotic granulosa cell death and autophagy needs to be further explored.

Rapid Simultaneous Determination of Cascade Metabolites of Acrylamide in Urine for Toxicokinetics Profiles and Short-Term Dietary Internal Exposure

The current study developed an ultrahigh-performance liquid chromatography tandem mass spectrometry method to simultaneously analyze cascade metabolites of acrylamide in urine of rats and humans, including acrylamide, glycidamide, N-acetyl-S-(2-carbamoylethyl)-l-cysteine (AAMA), N-acetyl-S-(2-carbamoylethyl)-l-cysteine-sulfoxide, N-acetyl-S-(2-carbamoyl-2-hydroxyethyl)-l-cysteine, and N-acetyl-S-(1-carbamoyl-2-hydroxyethyl)-l-cysteine. A tandem solid-phase extraction procedure was novelly used to purify all metabolites at once from human urine. The rapid analysis showed high sensitivity with LOD and LOQ ranges of 0.1-0.8 and 0.4-5.8 ng/mL, respectively, and achieved acceptable within-laboratory reproducibility (RSD < 12.0%) and spiking recovery (92.2%-117.3%) within 8 min per sample. Approximately 70.7 and 63.0% of ingested acrylamide were recovered during the toxicokinetics analysis from urine of male and female rats, respectively. For nonsmoking participants, the urinary levels of acrylamide and glycidamide were higher in men than women, whereas the urinary concentration of AAMA showed the opposite behavior. The current analysis provides methodological support of cascade metabolites of acrylamide for the dietary short-term internal exposure assessment of acrylamide.

Potential Adverse Public Health Effects Afforded by the Ingestion of Dietary Lipid Oxidation Product Toxins: Significance of Fried Food Sources

Exposure of polyunsaturated fatty acid (PUFA)-rich culinary oils (COs) to high temperature frying practices generates high concentrations of cytotoxic and genotoxic lipid oxidation products (LOPs) via oxygen-fueled, recycling peroxidative bursts. These toxins, including aldehydes and epoxy-fatty acids, readily penetrate into fried foods and hence are available for human consumption; therefore, they may pose substantial health hazards. Although previous reports have claimed health benefits offered by the use of PUFA-laden COs for frying purposes, these may be erroneous in view of their failure to consider the negating adverse public health threats presented by food-transferable LOPs therein. When absorbed from the gastrointestinal (GI) system into the systemic circulation, such LOPs may significantly contribute to enhanced risks of chronic non-communicable diseases (NCDs), e.g. cancer, along with cardiovascular and neurological diseases. Herein, we provide a comprehensive rationale relating to the public health threats posed by the dietary ingestion of LOPs in fried foods. We begin with an introduction to sequential lipid peroxidation processes, describing the noxious effects of LOP toxins generated therefrom. We continue to discuss GI system interactions, the metabolism and biotransformation of primary lipid hydroperoxide LOPs and their secondary products, and the toxicological properties of these agents, prior to providing a narrative on chemically-reactive, secondary aldehydic LOPs available for human ingestion. In view of a range of previous studies focused on their deleterious health effects in animal and cellular model systems, some emphasis is placed on the physiological fate of the more prevalent and toxic α,β-unsaturated aldehydes. We conclude with a description of targeted nutritional and interventional strategies, whilst highlighting the urgent and unmet clinical need for nutritional and epidemiological trials probing relationships between the incidence of NCDs, and the frequency and estimated quantities of dietary LOP intake.

Dietary Intake of Acrylamide and Risk of Breast, Endometrial, and Ovarian Cancers: A Systematic Review and Dose-Response Meta-analysis

Acrylamide is a probable human carcinogen. Aside from occupational exposures and smoking, diet is the main source of exposure in humans. We performed a systematic review of the association between estimated dietary intake of acrylamide and risk of female breast, endometrial, and ovarian cancers in nonexperimental studies published through February 25, 2020, and conducted a dose-response meta-analysis. We identified 18 papers covering 10 different study populations: 16 cohort and two case-control studies. Acrylamide intake was associated with a slightly increased risk of ovarian cancer, particularly among never smokers. For endometrial cancer, risk was highest at intermediate levels of exposure, whereas the association was more linear and positive among never smokers. For breast cancer, we found evidence of a null or inverse relation between exposure and risk, particularly among never smokers and postmenopausal women. In a subgroup analysis limited to premenopausal women, breast cancer risk increased linearly with acrylamide intake starting at 20 μg/day of intake. High acrylamide intake was associated with increased risks of ovarian and endometrial cancers in a relatively linear manner, especially among never smokers. Conversely, little association was observed between acrylamide intake and breast cancer risk, with the exception of premenopausal women.

Derivation of a No significant risk level (NSRL) for acrylamide

Acrylamide is included on the State of California's Proposition 65 list as a carcinogen. Acrylamide is found in cigarette smoke and in many types of foods, including breads, cereals, coffee, cookies, French fries, and potato chips. In 1990, California's Office of Environmental Health Hazard Assessment (OEHHA) established a no significant risk level (NSRL) of 0.2 μg/day for acrylamide. Since then, multiple cancer studies have been published. In this report, we developed an updated NSRL for acrylamide. Using benchmark dose modeling and a weight-of-evidence, non-threshold approach to identify the most sensitive species, cancer slope factors (CSFs) were derived based on combined incidences of statistically significant neoplastic lesions in the Harderian gland, lung, and stomach in male mice. We then used a toxicokinetic (TK)-based scaling approach to convert the animal CSF to a human equivalent CSF, which served as the basis for the NSRL of 1.1 μg/day at the cancer risk level of 1 in 100,000. This NSRL can be used in quantitative exposure assessments to assess compliance with Proposition 65 to ascertain either the need for or exemption from the Proposition 65 labeling requirement and drinking water discharge prohibition.

A Summary Report of FSCJ Workshop "Future Challenges and Opportunities in Developing Methodologies for Improved Human Risk Assessments"

This is a summary report of FSCJ (Food Safety Commission of Japan) workshop entitled "Future Challenges and Opportunities in Developing Methodologies for Improved Human Risk Assessments, which held in November 2018. Scientific advancements have facilitated the development of new methods for chemical risk assessments with the expansion of toxicological databases. They are promising tools to overcome challenges, such as situations of data insufficiency, estimation of internal exposure and prediction of hazard, and enable us to improve our human health risk assessment in food safety. In this review, current understandings on developments in chemical risk assessments, especially focusing on Threshold of Toxicological Concern (TTC) approach, non-testing and in-silico approaches (e.g. read-across), and physiologically based pharmacokinetics (PBPK) modeling are discussed as possible promising tools. It also discusses future challenges and opportunities regarding social environment buildings in which all stakeholders including scientific experts, risk managers and consumers are able to accept these new risk assessment technologies. International collaboration would increase and enhance the efficiency in forming innovative ideas and in translating them into regulatory practices. It would strengthen technical capacity of experts who contribute to regulatory decisions and also promote acceptance of new methodologies among stakeholders. Cross-sectional collaboration such as making good use of human data of pharmaceutical drugs will facilitate a development of fresh tools for food safety domains. Once a new methodology is recognized in risk assessment agencies as implementable, it needs to be acknowledged and accepted by wider range of different stakeholders. Such stakeholders include scientific experts who conduct risk assessment for the risk assessment agencies, food industries and consumers. Transparency in the risk assessment work performed by regulatory agencies should strengthen their credibility and promote the acceptance of risk assessment including the new methodologies used in it. At the same time, efforts should be continued by regulatory agencies to further communicate with consumers about the concept of risk-based assessment as well as the concept of uncertainty.

A Metabolomics-Inspired Strategy for the Identification of Protein Covalent Modifications

Identification of protein covalent modifications (adducts) is a challenging task mainly due to the lack of data processing approaches for adductomics studies. Despite the huge technological advances in mass spectrometry (MS) instrumentation and bioinformatics tools for proteomics studies, these methodologies have very limited success on the identification of low abundant protein adducts. Herein we report a novel strategy inspired on the metabolomics workflows for the identification of covalently-modified peptides that consists on LC-MS data preprocessing followed by statistical analysis. The usefulness of this strategy was evaluated using experimental LC-MS data of histones isolated from HepG2 and THLE2 cells exposed to the chemical carcinogen glycidamide. LC-MS data was preprocessed using the open-source software MZmine and potential adducts were selected based on the m/z increments corresponding to glycidamide incorporation. Then, statistical analysis was applied to reveal the potential adducts as those ions are differently present in cells exposed and not exposed to glycidamide. The results were compared with the ones obtained upon the standard proteomics methodology, which relies on producing comprehensive MS/MS data by data dependent acquisition and analysis with proteomics data search engines. Our novel strategy was able to differentiate HepG2 and THLE2 and to identify adducts that were not detected by the standard methodology of adductomics. Thus, this metabolomics driven approach in adductomics will not only open new opportunities for the identification of protein epigenetic modifications, but also adducts formed by endogenous and exogenous exposure to chemical agents.

Effect of acrylamide on BEAS-2B normal human lung cells: Cytotoxic, oxidative, apoptotic and morphometric analysis

Due to the broad toxic relevance of acrylamide, many measures have been taken since the 1900s. These measures increased day by day when acrylamide was discovered in foods in 2002, and its toxic spectrum was found to be wider than expected. Therefore, in some countries, the products with higher acrylamide content were restricted. On the other hand, the effects of acrylamide on the respiratory system cells have yet to be well understood. In this study, we aimed at investigating the effect of acrylamide on lung epithelial BEAS-2B cells. Initially, the cytotoxic effect of acrylamide on BEAS-2B was determined by MTT assay. Then, cellular oxidative stress was measured. Flow cytometry analysis was conducted for Annexin-V and caspase 3/7. Furthermore, Bax, Bcl-2 and Nrf-2 proteins were evaluated by immunocytochemistry. Finally, acrylamide-induced cellular morphological changes were observed under confocal and TEM microscopes. According to MTT results, the IC50 concentration of acrylamide was 2.00 mM. After acrylamide treatment, oxidative stress increased dose-dependently. Annexin V-labelled apoptotic cells and caspase 3/7 activity were higher than untreated cells in acrylamide-treated cells. Immunocytochemical examination revealed a marked decrease in Bcl-2, an increase in Bax and Nrf-2 protein staining upon acrylamide treatment. Furthermore, in confocal and TEM microscopy, apoptotic hallmarks were pronounced. In the present study, acrylamide was suggested to display anti-proliferative activity, decrease viability, induce apoptosis and oxidative stress and cause morphological changes in BEAS-2B cells.

Experimental and pan-cancer genome analyses reveal widespread contribution of acrylamide exposure to carcinogenesis in humans

Humans are frequently exposed to acrylamide, a probable human carcinogen found in commonplace sources such as most heated starchy foods or tobacco smoke. Prior evidence has shown that acrylamide causes cancer in rodents, yet epidemiological studies conducted to date are limited and, thus far, have yielded inconclusive data on association of human cancers with acrylamide exposure. In this study, we experimentally identify a novel and unique mutational signature imprinted by acrylamide through the effects of its reactive metabolite glycidamide. We next show that the glycidamide mutational signature is found in a full one-third of approximately 1600 tumor genomes corresponding to 19 human tumor types from 14 organs. The highest enrichment of the glycidamide signature was observed in the cancers of the lung (88% of the interrogated tumors), liver (73%), kidney (>70%), bile duct (57%), cervix (50%), and, to a lesser extent, additional cancer types. Overall, our study reveals an unexpectedly extensive contribution of acrylamide-associated mutagenesis to human cancers.

Cancer risk estimation of glycidol based on rodent carcinogenicity studies, a multiplicative risk model and in vivo dosimetry

Here we evaluate a multiplicative (relative) risk model for improved cancer risk estimation of genotoxic compounds. According to this model, cancer risk is proportional to the background tumor incidence and to the internal dose of the genotoxic compound. Furthermore, the relative risk coefficient per internal dose is considered to be approximately the same across tumor sites, sex, and species. In the present study, we demonstrate that the relative risk model is valid for cancer risk estimation of glycidol, a common food contaminant. Published tumor data from glycidol carcinogenicity studies in mice and rats were evaluated in combination with internal dose estimates from hemoglobin adduct measurements in blood from mice and rats treated with glycidol in short-term studies. A good agreement between predicted and observed tumor incidence in responding sites was demonstrated in the animals, supporting a relative risk coefficient that is independent of tumor site, sex, and species. There was no significant difference between the risk coefficients for mice (5.1% per mMh) and rats (5.4% per mMh) when considering internal doses of glycidol. Altogether, this mechanism-based risk model gives a reliable risk coefficient, which then was extrapolated to humans considering internal dose, and background cancer incidence.

Coffee consumption and risk of pancreatic cancer: a systematic review and dose-response meta-analysis

The association between coffee consumption and pancreatic cancer risk has been extensively studied; however, there is no consistent conclusion. Therefore, this meta-analysis study sought to evaluate dose-response relationship between them. A search was conducted using the PubMed and Web of Science databases. Thirteen high-quality cohort studies were identified, involving in 959,992 study participants and 3831 pancreatic cancer cases. Comparing the highest with lowest categories of coffee intake, the pooled relative risk (RR) was 1.08 (95% CI 0.94-1.25). For dose-response analysis, no evidence of a nonlinear dose-response association between coffee consumption and pancreatic cancer (p for nonlinearity =0.171) was found. The risk of pancreatic cancer was increased by 5.87% (RR =1.06, 95% CI 1.05-1.07) with the increment of one cup/day. Coffee consumption was identified to be related with the increasing risk of pancreatic cancer in a dose-response manner. Nevertheless, further mechanistic studies are needed to clarify the concerned issues.

Using the comet assay and lysis conditions to characterize DNA lesions from the acrylamide metabolite glycidamide

The alkaline comet assay and a cell-free system were used to characterise DNA lesions induced by treatment with glycidamide (GA), a metabolite of the food contaminant acrylamide. DNA lesions induced by GA were sensitively detected when the formamidopyrimidine-DNA-glycosylase (Fpg) enzyme was included in the comet assay. We used LC-MS to characterise modified bases from GA-treated naked DNA with and without subsequent Fpg treatment. N7-GA-Guanine and N3-GA-Adenine aglycons were detected in the supernatant showing some depurination of adducted bases; treatment of naked DNA with Fpg revealed no further increase in the adduct yield nor occurrence of other adducted nucleobases. We treated human lymphocytes with GA and found large differences in DNA lesion levels detected with Fpg, depending on the duration and the pH of the lysis step. These lysis-dependent variations in GA-induced Fpg sensitive sites paralleled those observed after treatment of cells with methyl methane sulfonate (MMS). On the other hand, oxidative lesions (8-oxoGuanine) induced by a photoactive compound (Ro 12-9786) plus light, and also DNA strand breaks induced by X-rays, were detected largely independently of the lysis conditions. The results suggest that the GA-induced lesions are predominantly N7-GA-dG adducts slowly undergoing imidazole ring opening at pH 10 as in the standard lysis procedure; such structures are substrate for Fpg leading to strand breaks. The data suggest that the characteristic alkaline lysis dependence of some DNA lesions may be used to study specific types of DNA modifications. The comet assay is increasingly used in regulatory testing of chemicals; in this context, lysis-dependent variations represent a novel approach to obtain insight in the molecular nature of a genotoxic insult.

Acrylamide Production in Autoclaved Rodent Feed

Sterilization of rodent feed by steam autoclaving is a common practice in many research institutions. Often we only considerthe beneficial effects of this process-the reduction of microbial contamination-and forget that the high temperatures andpressures can have negative effects on diet quality. The purpose of our study was to assess both the physical and chemicalchanges to a standard rodent feed autoclaved at multiple sterilization temperatures and the effects of the treated diets on mice. Pelleted NIH31 rodent feed was autoclaved at 4 sterilization temperatures (230, 250, 260, and 270 °F). Feed pellet hardness and the acrylamide concentrations of the diets were tested and compared with irradiated NIH31 feed. Study diets were fed to mice for 28 d, after which tissue samples were collected for analysis of acrylamide, glycidamide (the active metabolite of acrylamide), and genotoxicity. Both feed pellet hardness and acrylamide concentration increased with increasing sterilization temperatures; however, neither affected feed intake or body weight gain. Plasma acrylamide and glycidamide weresignificantly elevated only in mice fed NIH31 diet autoclaved at 270 °F compared with the irradiated feed, whereas urineacrylamide and glycidamide metabolites were significantly elevated in most autoclaved diets. Liver DNA adducts, whichcorrelate with genotoxicity, were significantly elevated in all autoclaved diets compared with the irradiated diet. Institutionsthat autoclave their animal diets should carefully consider the temperatures necessary to achieve feed sterilization and thetype of studies in which these autoclaved diets are used.

The polymorphism rs2480258 within CYP2E1 is associated with different rates of acrylamide metabolism in vivo in humans

In a recent study, we demonstrated that the variant allele of rs2480258 within intron VIII of CYP2E1 is associated with reduced levels of mRNA, protein, and enzyme activity. CYP2E1 is the most important enzyme in the metabolism of acrylamide (AA) by operating its oxidation into glycidamide (GA). AA occurs in food, is neurotoxic and classified as a probable human carcinogen. The goal of the present study was to further assess the role of rs2480258 by measuring the rate of AA > GA biotransformation in vivo. In blood samples from a cohort of 120 volunteers, the internal doses of AA and GA were assessed by AA and GA adducts to hemoglobin (Hb) measured by mass spectrometry. The rate of biotransformation was assessed by calculating the GA-Hb/AA-Hb ratio. To maximize the statistical power, 60 TT was compared to 60 CC-homozygotes and the results showed that TT homozygotes had a statistically significant reduced rate of biotransformation. Present results reinforced the notion that T-allele of rs2480258 is a marker of low functional activity of CYP2E1. Moreover, we studied the role of polymorphisms (SNPs) within glutathione-S-transferases (GSTs) enzymes and epoxide hydrolase (EPHX), verifying previous findings that SNPs within GSTs and EPHX influence the metabolism rate.

Dietary acrylamide intake and risk of breast cancer: The Japan Public Health Center-based Prospective Study

Acrylamide forms during cooking and is classified as a probable carcinogen in humans, mandating the need for epidemiological studies of dietary acrylamide and cancers. However, the risk of dietary acrylamide exposure to breast cancer in Japanese women has not been assessed. We investigated the association between dietary acrylamide intake and risk of breast cancer in the Japan Public Health Center-based Prospective Study. The present study included 48 910 women aged 45-74 years who responded to a 5-year follow-up survey questionnaire. Dietary acrylamide intake was assessed using a validated food frequency questionnaire. Cox proportional hazards regression models were used to estimate hazard ratios and 95% confidence intervals. During an average of 15.4 years of follow up, 792 breast cancers were diagnosed. Energy-adjusted dietary acrylamide intake was not associated with the risk of breast cancer (adjusted hazard ratio for highest versus lowest tertile = .95, 95% confidence intervals: 0.79-1.14, P-trend = .58). Further, no significant associations were observed when stratified analyses were conducted by smoking status, coffee consumption, alcohol consumption, body mass index, menopausal status, estrogen receptor status, and progesterone receptor status. In conclusion, dietary acrylamide intake was not associated with the risk of breast cancer in this population-based prospective cohort study of Japanese women.

Parallelogram based approach for in vivo dose estimation of genotoxic metabolites in humans with relevance to reduction of animal experiments

When employing metabolism studies of genotoxic compounds/metabolites and cancer tests for risk estimation, low exposure doses in humans are roughly extrapolated from high exposure doses in animals. An improvement is to measure the in vivo dose, i.e. area under concentration-time curve (AUC), of the causative genotoxic agent. In the present work, we propose and evaluate a parallelogram based approach for estimation of the AUC of genotoxic metabolites that incorporates in vitro metabolic data and existing knowledge from published in vivo data on hemoglobin (Hb) adduct levels, using glycidamide (GA) as a case study compound that is the genotoxic metabolite of acrylamide (AA). The estimated value of AUC of GA per AUC of AA from the parallelogram approach vs. that from Hb adduct levels measured in vivo were in good agreement; 0.087 vs. 0.23 in human and 1.4 vs. 0.53 in rat, respectively. The described parallelogram approach is simple, and can be useful to provide an approximate estimation of the AUC of metabolites in humans at low exposure levels for which sensitive methods for analyzing the metabolites are not available, as well as aid in reduction of animal experiments for metabolism studies that are to be used for cancer risk assessment.

Mechanistic roles of microRNAs in hepatocarcinogenesis: A study of thioacetamide with multiple doses and time-points of rats

Environmental chemicals exposure is one of the primary factors for liver toxicity and hepatocarcinoma. Thioacetamide (TAA) is a well-known hepatotoxicant and could be a liver carcinogen in humans. The discovery of early and sensitive microRNA (miRNA) biomarkers in liver injury and tumor progression could improve cancer diagnosis, prognosis, and management. To study this, we performed next generation sequencing of the livers of Sprague-Dawley rats treated with TAA at three doses (4.5, 15 and 45 mg/kg) and four time points (3-, 7-, 14- and 28-days). Overall, 330 unique differentially expressed miRNAs (DEMs) were identified in the entire TAA-treatment course. Of these, 129 DEMs were found significantly enriched for the “liver cancer” annotation. These results were further complemented by pathway analysis (Molecular Mechanisms of Cancer, p53-, TGF-β-, MAPK- and Wnt-signaling). Two miRNAs (rno-miR-34a-5p and rno-miR-455-3p) out of 48 overlapping DEMs were identified to be early and sensitive biomarkers for TAA-induced hepatocarcinogenicity. We have shown significant regulatory associations between DEMs and TAA-induced liver carcinogenesis at an earlier stage than histopathological features. Most importantly, miR-34a-5p is the most suitable early and sensitive biomarker for TAA-induced hepatocarcinogenesis due to its consistent elevation during the entire treatment course.