Commentary of the SKLM to the EFSA opinion on risk assessment of N-nitrosamines in food.

Dietary exposure to N-nitrosamines has recently been assessed by the European Food Safety Authority (EFSA) to result in margins of exposure that are conceived to indicate concern with respect to human health risk. However, evidence from more than half a century of international research shows that N-nitroso compounds (NOC) can also be formed endogenously. In this commentary of the Senate Commission on Food Safety (SKLM) of the German Research Foundation (DFG), the complex metabolic and physiological biokinetics network of nitrate, nitrite and reactive nitrogen species is discussed with emphasis on its influence on endogenous NOC formation. Pioneering approaches to monitor endogenous NOC have been based on steady-state levels of N-nitrosodimethylamine (NDMA) in human blood and on DNA adduct levels in blood cells. Further NOC have not been considered yet to a comparable extent, although their generation from endogenous or exogenous precursors is to be expected. The evidence available to date indicates that endogenous NDMA exposure could exceed dietary exposure by about 2-3 orders of magnitude. These findings require consolidation by refined toxicokinetics and DNA adduct monitoring data to achieve a credible and comprehensive human health risk assessment.

DRUG RELATED NITROSOGENESIS, PHOTOCARCINOGENESIS AND ONCOPHARMACOGENESIS OF NODULAR MELANOMA: A CASE RELATED ANALYSIS CONCERNING THE POLYCONTAMINATION OF THE POLYMEDICATION WITH VALSARTAN/HYDROCHLOROTHIAZIDE AND BISOPROLOL.

Despite the fact that the pathogenesis of cutaneous melanoma is shrouded in mystery, factors that have been neglected or unnoticed until now have come to the attention in recent years, and in all likelihood, they could also be pivotal. These factors, known as nitrosamines or NDSRIs, are characterized by high carcinogenic and mutagenic potency, and some of them have demonstrated these properties to human DNA as well. Unfortunately, these ingredients also turn up as contaminants in about 300 of the most widely distributed drugs worldwide. According to the most recent literature, some of these ingredients are also identified as potent photocarcinogens, as well as human carcinogens. The intake of these carcinogens in the context of polycontamination of polymedication, has been associated for years with the occurrence of melanomas. The need for cataloguing of nitrosamines , as well as their accurate labelling on drug packaging, would help to classify them even more accurately as carcinogens affecting human DNA. We present once again a patient , who developed nodular melanoma within the context of the intake of 3 potentially nitrosamine/ NDSRIs contaminated antihypertensive drugs (valsartan/ Hydrochlorothiazide/ bisoprolol). Pathogenetic aspects concerning drug-induced nitrosogenesis, photocarcinogenesis and oncopharmacogenesis of skin cancer are discussed. Nitrosogenesis' of Cancer as concept in the medical literature has been known for decades, but in relation to other forms of human cancer. Exogenously mediated drug-mediated nitrosogenesis is a logically conditioned and newly defined concept whose significance with respect to the clinical manifestation of skin cancer is only beginning to grow.

PERIOCULAR HIGH RISK BCCS AFTER ADDITIONAL/PARALLEL INTAKE OF TORASEMIDE, MOXONIDINE AND MIRABEGRON: IMPORTANT LINKS TO SKIN CANCER RELATED (PHOTO-) NITROSOGENESIS IN THE CONTEXT OF PHARMACO-ONCOGENESIS.

The Nitrosogenesis of skin cancer is a modern newly introduced concept in medicine, mainly concerning melanoma, but also keratinocytic cancers such as basal cell carcinoma. The nitroso-contamination of more than 300 drugs worldwide and the permanent (relatively short-term) intake of mutagen-contaminated drugs could create serious prerequisites for the development of skin cancer. Retrospective but also prospective analyses following potentially contaminated polymedication with a heterogeneous type of nitrosamines in real patients are indicative of a causal connection rather than a sporadic association between 1) intake of a possibly nitrosamine-contaminated drug and 2) generation of keratinocytic skin cancer. The pathogenesis of high-risk periocular localized basal cell carcinomas was until recently shrouded in mystery as it was mainly and until now associated with 1) intake of phototoxic drugs and 2) intense exposure to UV radiation (without intake of drugs), 3) congenital or acquired immunodeficiencies, and 4) Goltz Gorlin syndrome or 5) Xeroderma pigmentosum. Nitrosamines/ NDSRIs within the framework of polycotaminated drug intake appear to be one reasonable additional explanation for the association between carcinogen intake and subsequent skin cancer development and progression, and a relatively short-term one at that. Recently published scientific data provide information on a new ability of some of the nitrosamines - namely that some of them are photocarcinogenic or genotoxic after activation with UVA radiation. We present 4 patients who developed high-risk periocular localized basal cell carcinomas of the skin after/within the intake of potentially nitrosamine-contaminated drugs. The presented data are confirmatory with respect to previously published scientific observations on the carcinogenic effects of valsartan, candesartan, bisoprolol, metoprolol, perindopril, lisinopril and amlodipine. The contribution of newly validated data concerning potential/actual carcinogenic/genotoxic activity in the article is also due to the following newly announced nitroso preparations: torasemide, moxonidine and mirabegron. The expansion of the ˝bases of the pyramid˝ determining the stability of drug related (Photo) Nitrosogenesis/ Carcinogenesis (in terms of skin cancer generation) is growing daily. Exogenously/drug-induced Nitrosogenesis and the subsequently triggered carcinogenesis are a completely new explanatory concepts concerning the pathogenesis of skin tumors that remained unanalyzed and hidden for decades. Until now. The official lack of 1) availability, and of 2) precise concentrations regarding nitrosamines in medicinal preparations, are some of the most unexplained acts of irresponsibility to end-users and remain for the moment without a definitive answer from either regulators and manufacturers respectively. Polycontamination of polymedication in polymorbid patients remains highly problematic, at least as a cofactor in the development and progression of keratinocytic cancers, and this in the short term. Recently published data but also data from the past are suggestive that nitrosamines in tobacco are pivotal in the development of acquired mutations in p53 and RAS oncogenes in humans and rodents. The same genes are also affected by mutations in keratinocytic cancer patients. The overlapping mutation patterns of UV radiation-induced mutations in target genes such as p53 and RAS with those caused by some nitrosamines is indicative of a synergism available in terms of gene toxicity or possibly photocarcinogenicity of the latter. What leads the scientific community to believe that the nitrosamines in drugs, similar in composition and carcinogenic potency, act differently, is unclear. The link between drug intake, nitrosamine contamination, generation of some acquired mutations and subsequent cancer development becomes more than obvious and logically conditioned. The thesis of the controlled spread of cancer sounds more than logical today because: whoever controls and regulates the spread of carcinogens/mutagens/nitrosamines is also able to control the occurrence and spread of skin cancer. The Pharmaco-oncogenesis of skin cancer is determined by exogenously mediated Nitrosogenesis or the permissive availability for certain nitrosamines in drugs worldwide.

EDUCATION FROM DERMATOLOGISTS: THE SIMULTANEOUSLY DEVELOPMENT OF 16 KERATINOCYTIC CANCERS AFTER USE OF METFORMIN IN COMBINATION WITH LOSARTAN/ HYDROCHLOROTHIAZIDE, METOPROLOL AND NIFEDIPINE- IMPORTANT LINKS TO DRUG RELATED (PHOTO)-NITROSO-CARCINOGENESIS AND ONCOPHARMACOGENESIS.

Oncopharmacogenesis and Drug-Induced Skin cancer related Nitrosogenesis are newly introduced concepts in the medical literature that owe their genesis or presence to the carcinogens/ mutagens, also known as nitrosamines/NDSRIs, which are present in a heterogeneous class of drugs. The contribution to the origin of these 2 concepts is entirely due to 1) the functions and efficacy of FDA in terms of control and identification of these carcinogens, and 2) the establishment of clinicopathological correlations by the dermatologists, occurring during drug intake. According to recent FDA data, the concentration of NDMA in just one metformin tablet could be up to more than 5-fold increased. The intake of 3 to 6 tablets per day should result in a carcinogen intake that is 15 to 30 times elevated within the day and within the monomedication alone. It is these circumstances that paraphrase/ ˝betonate˝ concepts such as Onco-Pharmacogenesis and Drug-mediated Nitrosogenesis of skin cancer. Although not officially declared, these mutagens are present and have been in forced tolerance mode for the last 30-40 years. And after their intake, multiple cancers have been found to develop. The concomitant use of other nitrosamine-contaminated drugs such as losartan/hydrochlorothiazide, metoprolol and nefidipine should certainly not be surprising when it could also be associated with the development of exactly 16 keratinocytic tumours as in the case presented by us. Recent evidence in medical literature has linked the nitrosamine N-nitrosomorpholine (NMOR) with the direct development of its subsequent mutagenic action in rodents following irradiation with UVA. This fact leaves open the question of the potentially available photocarcinogenic action of the other nitrosamines in humans found in medicinal preparations. This is what necessitates a clarification of the concept of Photo-Nitroso-Carcinogenesis/ Oncogenesis in humans and its relationship to skin cancer. The overlap of the mutational patterns of some of the nitrosamine-induced mutations in target genes such as p53 and RAS oncogenes, with those of UV light-induced mutations - or practically the same ones mentioned above, suggest a possible significant role of the Drug-Induced Photo-Nitroso-Carcinogenesis of keratinocyte cancer in the context of Onco-Pharmacogenesis. Future analyses should focus on elucidating the photocarcinogenic effect of nitrosamines in drug preparations and differentiating Skin cancer Nitrosogenesis from ˝pure˝ Photo-Carcinogenesis and Nitroso-Photo-Carcinogenesis. The localization of the tumors in the area of the UV-exposed sites within the potential/actual contamination of the 4 preparations (simultaneously) in the described patient are indicative of a possible pathogenetic influence in the context of the already mentioned Nitroso-(Photo)carcinogenesis. Polycontamination of polymedication remains a so far unresolvable problem.

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.

hOGG1: A novel mediator in nitrosamine-induced esophageal tumorigenesis.

BACKGROUND: The effect of human 8-Oxoguanine DNA Glycosylase (hOGG1) on exogenous chemicals in esophageal squamous cell carcinoma (ESCC) remain unclear. The study plans to determine hOGG1 expression levels in ESCC and possible interactions with known environmental risk factors in ESCC. MATERIAL AND METHODS: We analyzed levels of exposure to urinary nitrosamines in volunteers from high and low prevalence areas by GC-MS. And we performed the interaction between hOGG1 gene and nitrosamine disinfection by-products by analyzing hOGG1 gene expression in esophageal tissues. RESULTS: In ESCC, nitrosamine levels were significantly increased and hOGG1 mRNA expression levels were significantly decreased. There was a statistically significant interaction between reduced hOGG1 mRNA levels and non-tap drinking water sources in ESCC. The apparent indirect association between ESCC and NMEA indicated that 33.4% of the association between ESCC and NMEA was mediated by hOGG1. CONCLUSION: In populations which exposed to high levels of environmental pollutants NDMA, low expression of hOGG1 may promote the high incidence of esophageal cancer in Huai'an. hOGG1 may be a novel mediator in nitrosamine-induced esophageal tumorigenesis.

Metabolism-dependent mutagenicity of two structurally similar tobacco-specific nitrosamines (N-nitrosonornicotine and N-nitrosoanabasine) in human cells, partially different CYPs being activating enzymes.

N-nitrosonornicotine (NNN) and N-nitrosoanabasine (NAB) are both tobacco-specific nitrosamines bearing two heterocyclic amino groups, NAB bearing an extra -CH2- group (conferring a hexa- rather than penta-membered cycle) but with significantly decreased carcinogenicity. However, their activating enzymes and related mutagenicity remain unclear. In this study, the chemical-CYP interaction was analyzed by molecular docking, thus the binding energies and conformations of NNN for human CYP2A6, 2A13, 2B6, 2E1 and 3A4 appeared appropriate as a substrate, so did NAB for human CYP1B1, 2A6, 2A13 and 2E1. The micronucleus test in human hepatoma (HepG2) cells with each compound (62.5-1000 µM) exposing for 48 h (two-cell cycle) was negative, however, pretreatment with bisphenol AF (0.1-100 nM, CYPs inducer) and ethanol (0.2% v:v, CYP2E1 inducer) potentiated micronucleus formation by both compounds, while CITCO (1 µM, CYP2B6 inducer) selectively potentiated that by NNN. In C3A cells (endogenous CYPs enhanced over HepG2) both compounds induced micronucleus, which was abolished by 1-aminobenzotriazole (60 µM, CYPs inhibitor) while unaffected by 8-methoxypsoralen (1 µM, CYP2A inhibitor). Consistently, NNN and NAB induced micronucleus in V79-derived recombinant cell lines expressing human CYP2B6/2E1 and CYP1B1/2E1, respectively, while negative in those expressing other CYPs. By immunofluorescent assay both compounds selectively induced centromere-free micronucleus in C3A cells. In PIG-A assays in HepG2 cells NNN and NAB were weakly positive and simply negative, respectively; however, in C3A cells both compounds significantly induced gene mutations, NNN being slight more potent. Conclusively, both NNN and NAB are mutagenic and clastogenic, depending on metabolic activation by partially different CYP enzymes.

Mechanisms of Nitrosamine Mutagenicity and Their Relationship to Rodent Carcinogenic Potency.

A thorough literature review was undertaken to understand how the pathways of N-nitrosamine transformation relate to mutagenic potential and carcinogenic potency in rodents. Empirical and computational evidence indicates that a common radical intermediate is created by CYP-mediated hydrogen abstraction at the α-carbon; it is responsible for both activation, leading to the formation of DNA-reactive diazonium species, and deactivation by denitrosation. There are competing sites of CYP metabolism (e.g., ß-carbon), and other reactive species can form following initial bioactivation, although these alternative pathways tend to decrease rather than enhance carcinogenic potency. The activation pathway, oxidative dealkylation, is a common reaction in drug metabolism and evidence indicates that the carbonyl byproduct, e.g., formaldehyde, does not contribute to the toxic properties of N-nitrosamines. Nitric oxide (NO), a side product of denitrosation, can similarly be discounted as an enhancer of N-nitrosamine toxicity based on carcinogenicity data for substances that act as NO-donors. However, not all N-nitrosamines are potent rodent carcinogens. In a significant number of cases, there is a potency overlap with non-N-nitrosamine carcinogens that are not in the Cohort of Concern (CoC; high-potency rodent carcinogens comprising aflatoxin-like-, N-nitroso-, and alkyl-azoxy compounds), while other N-nitrosamines are devoid of carcinogenic potential. In this context, mutagenicity is a useful surrogate for carcinogenicity, as proposed in the ICH M7 (R2) (2023) guidance. Thus, in the safety assessment and control of N-nitrosamines in medicines, it is important to understand those complementary attributes of mechanisms of mutagenicity and structure-activity relationships that translate to elevated potency versus those which are associated with a reduction in, or absence of, carcinogenic potency.

Risk characterization of N-nitrosodimethylamine in pharmaceuticals.

Since 2018, N-nitrosodimethylamine (NDMA) has been a reported contaminant in numerous pharmaceutical products. To guide the pharmaceutical industry, FDA identified an acceptable intake (AI) of 96 ng/day NDMA. The approach assumed a linear extrapolation from the Carcinogenic Potency Database (CPDB) harmonic-mean TD50 identified in chronic studies in rats. Although NDMA has been thought to act as a mutagenic carcinogen in experimental animals, it has not been classified as a known human carcinogen by any regulatory agency. Humans are exposed to high daily exogenous and endogenous doses of NDMA. Due to the likelihood of a threshold dose for NDMA-related tumors in animals, we believe that there is ample scientific basis to utilize the threshold-based benchmark dose or point-of-departure (POD) approach when estimating a Permissible Daily Exposure limit (PDE) for NDMA. We estimated that 29,000 ng/kg/day was an appropriate POD for calculating a PDE. Assuming an average bodyweight of 50 kg, we expect that human exposures to NDMA at doses below 5800 ng/day in pharmaceuticals would not result in an increased risk of liver cancer, and that there is little, if any, risk for any other type of cancer, when accounting for the mode-of-action in humans.

A critical review of advances in tumor metabolism abnormalities induced by nitrosamine disinfection by-products in drinking water.

Intensified sanitation practices amid the recent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak might result in the increased release of chloramine disinfectants into surface water, significantly promoting the formation of nitrosamine disinfection by-products (DBPs) in drinking water. Unfortunately, these nitrosamine DBPs exhibit significant genotoxic, carcinogenic, and mutagenic properties, whereas chlorinating disinfectants remain in global practice. The current review provides valuable insights into the occurrence, identification, contamination status, exposure limits, and toxicity of the new unregulated disinfection by-products (nitrosamine DBPs) in drinking water. As a result, concentrations of nitrosamine DBPs far exceed allowable limits in drinking water, and prolonged exposure has the potential to cause metabolic disorders, a critical step in tumor initiation and progression. Importantly, based on recent research, we have concluded the role of nitrosamines DBPs in different metabolic pathways. Remarkably, nitrosamine DBPs can induce chronic inflammation and initiate tumors by activating sphingolipid and polyunsaturated fatty acid metabolism. Regarding amino acid and nucleotide metabolism, nitrosamine DBPs can inhibit tryptophan metabolism and de novo nucleotide synthesis. Moreover, inhibition of de novo nucleotide synthesis fails to repair DNA damage induced by nitrosamines. Additionally, the accumulation of lactate induced by nitrosamine DBPs may act as a pivotal signaling molecule in communication within the tumor microenvironment. However, with the advancement of tumor metabolomics, understanding the role of nitrosamine DBPs in causing cancer by inducing metabolic abnormalities significantly lags behind, and specific mechanisms of toxic effects are not clearly defined. Urgently, further studies exploring this promising area are needed.

The comprehensive prediction of carcinogenic potency and tumorigenic dose (TD50) for two problematic N-nitrosamines in food: NMAMPA and NMAMBA using toxicology in silico methods.

The identification and toxicological assessment of potential carcinogens is of paramount importance for public health and safety. This study aimed to predict the carcinogenic potency and tumorigenic dose (TD50) for two problematic N-nitrosamines (N-NAs) commonly found in food: N-2-methylpropyl-N-1-methylacetonylnitrosamine (NMAMPA, CAS: 93755-83-0) and N-3-Methylbutyl-N-1-methylacetonylnitrosamine (NMAMBA, CAS: 71016-15-4). To achieve this goal, in silico toxicology methods were employed due to their practical applications and potential in risk assessment. The justification for conducting these studies was incoherent results published by the European Food Safety Authority (EFSA). For this purpose, we applied various in silico tools, including qualitative methods (ToxTree, ProTox II and CarcinoPred-EL) and quantitative methods (QSAR Toolbox and LAZAR) were applied to predict the carcinogenic potency. These tools leverage computational approaches to analyze chemical structures for finding toxicophores and generating predictions, making them efficient alternatives to traditional in vivo experiments. The results obtained indicated that N-NAs are carcinogenic compounds, and quantitative data was obtained in the form of estimated doses of TD50 for the compounds tested.

Genotoxicity and the stability of N-nitrosomorpholine activity following UVA irradiation.

This study investigated N-nitrosomorpholine (NMOR) genotoxicity following UVA irradiation without metabolic activation. Following UVA irradiation, the photo treated NMOR (irradiated NMOR) was directly mutagenic, without UVA or metabolic activation, in the Ames test. The activity was relatively stable, and approximately 79% of the activity remained after 10 days of storage at 37 °C, 4 °C, or -20 °C. Micronuclei (MN) formation was observed in HaCaT cells after treatment with irradiated NMOR without metabolic activation. The action spectrum of MN formation in response to NMOR irradiation followed the NMOR absorption curve. In vivo, MN formation was observed in the peripheral blood reticulocytes of mice injected with irradiated NMOR under the inhibition of cytochrome P450-mediated metabolism of NMOR. Volatile NMOR may attach to environmental materials and be irradiated with environmental UVA light. Photoactivated NMOR-attached air pollutants could float in the air and fall onto the human body, leading to genotoxicity induced by the irradiated NMOR.

N-Nitrosomorpholine-induced oncocytic transformation in rat endocrine organs.

BACKGROUND: N-Nitrosomorpholine (NMO) is one of the most common N-nitroso compounds. An oncocytic transformation has been demonstrated in renal tubules of NMO-treated rats. In our study, we aimed to investigate the potential transformation of oncocytic cells in 6 endocrine organs, i.e., thyroid, adrenal and pituitary glands, pancreas, testis, and bone, of NMO-exposed rats. METHODS: Thirty male rats were born and raised. Fifteen of them were given a single dose of 320 mg NMO per kg body weight, dissolved in drinking water, by a gavage tube. At the end of 52 weeks, the animals in both series were killed. Right after the killing, 6 different endocrine organs (hypophysis, thyroid, pancreas, adrenal gland, bone [femur], and testicles) of each animal were excised. RESULTS: There was no evidence of oncocytic cell development in the control group. In contrast, oncocytes were observed in 8 out of 13 NMO-treated rats: 2 in the adrenal sections, 1 in the thyroid sections, 3 in the pituitary sections, and 2 in the pancreas sections. Thesticle and bone sections were completely normal. CONCLUSIONS: We showed that NMO induced an oncocytic change in pancreas, thyroid, pituitary, and adrenal glands. To date, no identified specific environmental risk factors that lead to an oncocytic transformation in endocrine glands have been reported previously. Given the increasing prevalence of endocrine-disrupting chemicals in the environment, personal care products, manufactured goods, and food sources, there is a need to advance our understanding of the pathological mechanisms underlying oncocytosis in endocrine organs.

Diallyl trisulfide inhibits 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone-induced lung cancer via modulating gut microbiota and the PPARγ/NF-κB pathway.

Smoking is the primary risk factor for developing lung cancer. Chemoprevention could be a promising strategy to reduce the incidence and mortality rates of lung cancer. Recently, we reported that A/J mice exposed to tobacco smoke carcinogens displayed the reshaping of gut microbiota. Additionally, garlic oil was found to effectively inhibit the carcinogenic effects of tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in lung tumorigenesis. Diallyl trisulfide (DATS), which is the predominant compound in garlic oil, exhibits various biological activities. To further explore the chemopreventive action and potential mechanism of DATS on lung tumorigenesis, we established a lung adenocarcinoma model in A/J mice stimulated by NNK. Subsequently, we employed multi-omics combined molecular biology technologies to clarify the mechanism. The results indicated that DATS significantly decreased the number of lung tumors in NNK induced A/J mice. Interestingly, we discovered that DATS could modulate gut microbiota, particularly increasing the abundance of F. rodentium, which has inhibitory effects on tumor growth. Mechanistically, DATS could activate the PPARγ pathway, leading to the negative regulation of the NF-κB signaling pathway and subsequent suppression of NF-κB-mediated inflammatory factors. Collectively, these findings provide support for DATS as a potential novel chemopreventive agent for tobacco carcinogen-induced lung cancer.

N-Nitrosamines: a potential hazard in processed meat products.

Nitrite, nitrate, and their salts are added to processed meat products to improve color, flavor, and shelf life and to lower the microbial burden. N-Nitrosamine compounds are formed when nitrosing agents (such as secondary nitrosamines) in meat products interact with nitrites and nitrates that have been added to the meat. With the consumption of such meat products, nitrosation reactions occur in the human body and N-nitrosamine formation occurs in the gastrointestinal tract. Despite the benefits nitrites and nitrates have on food, their tendency to create nitrosamines and an increase in the body's nitrous amine load presents health risks. The inclusion of nitrosamine compounds in possible and probable carcinogen classes according to the International Agency for Research on Cancer requires a re-examination of the literature review on processed meat products. This article evaluates the connections between various cancer types and nitrosamines found in processed meat products. © 2023 Society of Chemical Industry.

Ames test study designs for nitrosamine mutagenicity testing: qualitative and quantitative analysis of key assay parameters.

The robust control of genotoxic N-nitrosamine (NA) impurities is an important safety consideration for the pharmaceutical industry, especially considering recent drug product withdrawals. NAs belong to the 'cohort of concern' list of genotoxic impurities (ICH M7) because of the mutagenic and carcinogenic potency of this chemical class. In addition, regulatory concerns exist regarding the capacity of the Ames test to predict the carcinogenic potential of NAs because of historically discordant results. The reasons postulated to explain these discordant data generally point to aspects of Ames test study design. These include vehicle solvent choice, liver S9 species, bacterial strain, compound concentration, and use of pre-incubation versus plate incorporation methods. Many of these concerns have their roots in historical data generated prior to the harmonization of Ames test guidelines. Therefore, we investigated various Ames test assay parameters and used qualitative analysis and quantitative benchmark dose modelling to identify which combinations provided the most sensitive conditions in terms of mutagenic potency. Two alkyl-nitrosamines, N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA) were studied. NDMA and NDEA mutagenicity was readily detected in the Ames test and key assay parameters were identified that contributed to assay sensitivity rankings. The pre-incubation method (30-min incubation), appropriate vehicle (water or methanol), and hamster-induced liver S9, alongside Salmonella typhimurium strains TA100 and TA1535 and Escherichia coli strain WP2uvrA(pKM101) provide the most sensitive combination of assay parameters in terms of NDMA and NDEA mutagenic potency in the Ames test. Using these parameters and further quantitative benchmark dose modelling, we show that N-nitrosomethylethylamine (NMEA) is positive in Ames test and therefore should no longer be considered a historically discordant NA. The results presented herein define a sensitive Ames test design that can be deployed for the assessment of NAs to support robust impurity qualifications.

In vitro permeation of nicotine and tobacco specific nitrosamines from smokeless tobacco product extracts in a 3D buccal tissue model.

Tobacco product use is a risk factor in the development of oral cancer, although epidemiology studies show this risk is far less with smokeless tobacco product use than cigarette smoking. While smokeless tobacco contains harmful and potentially harmful constituents (HPHCs), the oral permeation of HPHCs in oral tobacco products is not completely understood. To improve the understanding, three different extract concentrations of the CORESTA reference products (CRP) for snus (CRP1.1) and moist snuff (CRP2.1) were applied to cellular tissue derived from two donors of EpiOral™ model, a 3D human buccal model, and permeation of nicotine and tobacco-specific nitrosamines (TSNAs) were measured over two hours. Permeation of 0.15% caffeine in complete artificial saliva and cell viability were also measured. Results showed that a consistent and concentration dependent cumulative permeation of nicotine and TSNAs was observed with high percent recovery in all conditions. A high degree of sensitivity was seen for all analytes, with minimal cytotoxicity for both CRPs. The data presented here show the EpiOral™ model is fit-for-purpose to evaluate the permeation of nicotine and TSNAs in nicotine-containing snus and moist snuff oral tobacco.

N-nitrosamines induced gender-dimorphic effects on infant rats at environmental levels.

The safety of drinking water has always been a concern for people all over the world. N-nitrosamines (NAs), a kind of nitrogenous disinfection by-products (N-DBPs), are generally detected as a mixture in drinking water at home and abroad. Studies have shown that individual NAs posed strong carcinogenicity at high concentrations. However, health risks of NAs at environmental levels (concentrations in drinking water) are still unclear. Therefore, the potential health risks of environmentally relevant NAs exposure in drinking water needs to be conducted. In this study, blood biochemical analysis and metabolomics based on nuclear magnetic resonance (NMR) were performed to comprehensively investigate NAs induced metabolic disturbance in infant rats at environmental levels. Results of blood biochemical indices analysis indicated that AST in the serum of male rats in NAs-treated group exhibited a significant gender-specific difference. Multivariate statistics showed that two and eight significantly disturbed metabolic pathways were identified in the serum samples of NAs-treated male and female rats, respectively. In the urine samples of NAs-treated female rats, glycine, serine, and threonine metabolism pathway was significantly disturbed; while three significantly disturbed metabolic pathways were found in the urine of NAs-treated male rats. Finally, results of spearman correlation coefficients suggested that the disturbances of metabolism profile in serum and urine were correlated with changes in the gut microbiota (data derived from our published paper). Data presented here aimed to generate new health risk data of NAs mixture exposure at environmental levels and provide theoretical support for drinking water safety management. ENVIRONMENTAL IMPLICATION: N-nitrosamines (NAs) are a kind of nitrogenous disinfection by-products (N-DBPs) generated during drinking water disinfection processes. Herein, health risks of NAs at environmental levels (concentrations in drinking water) are investigated using blood biochemical analysis and nuclear magnetic resonance (NMR)-based metabolomics. Results confirmed NAs induced gender-specific on the metabolism in rat and the disturbances of metabolism profile in serum and urine were correlated with changes in the gut microbiota. Data presented here aimed to generate new health risk data of NAs mixture exposure at environmental levels and provide theoretical support for drinking water safety management.

METASTATIC NODULAR MELANOMA DEVELOPING ON NEVUS SPILUS DURING INTAKE OF BETA BLOCKERS (BISOPROLOL/NEBIVOLOL) AND ACE INHIBITORS (PERINDOPRIL). POTENTIAL LINKS TО THE DRUG RELATED NITROSOGENESIS/CARCINOGENESIS, DUNNING-KRUGER EFFECT AND GENETIC WEAPONS OF THE NEW GENERATION.

Drug-induced Nitrosogenesis/Carcinogenesis turns out to be a ubiquitous, pervasive, large-scale, poorly controllable concept for the academic community, which underlies the long-term, permanent modification of the human genome by contact with nitrosamines/NDSRIs, which ultimately leads to the generation of diverse cancers, but also melanoma in particular. The discovery of a (currently) unclassifiable number of nitroso derivatives/genome modifiers in the most commonly distributed drugs worldwide (in about 300 preparations according to the FDA/includes beta blockers/bisoprolol/nebivolol and ACE inhibitors/perindopril), their forced tolerability, attributed as a necessity or lack of alternative also to the present (but also to future periods), and their proven carcinogenicity (already 70 years ago), suggest a kind of creepy form of experiment to which public health is subjected worldwide. The creation of a universal nitroso-comfort of pharmaceutical companies and the regulation of a permanent intake of carcinogens in drugs for years to come, but also decades back, suggest possible cartel agreements between the regulation/distribution unit and that of production cycles. These "agreements" are becoming increasingly evident and in all likelihood position nitrosogenesis from a until recently unknown element, to a pathogenetic factor of paramount importance. Melanoma could be viewed precisely as the controlled end gene-modified product of drug-mediated nitrosogenesis/carcinogenesis, proven to be a locoregional (but not only) phenomenon hundreds if not thousands of times. The dilemma stays: Are the nitrosamines in drugs genetic weapons, ethnic bioweapons for silent war ? The nitrosogenesis concerning melanoma leads to the logical conclusion that cancer is in fact a largely controlled set event or, according to others, a forced necessity of evolutionary globalization processes to purge the population in certain regions. In favor of this statement indicative are namely: 1) lack of regulatory control/results of such conducted, 2) complete information veil for the end user regarding contamination with carcinogens/nitrosamines in certain batches or all batches of drugs, 3) misinformation and lack of transparency regarding the concept of nitrosogenesis also for the academic community, as well as 4) the impunity to pharmaceutical conglomerates after criminal negligence/controlled criminogenicity proven thousands of times by the FDA/EMA leading to regulatory controlled drug mediated genocide of the human population in certain areas on a daily basis. And most important of all: 5) the lack of refusal to eliminate these drugs, i.e. - the imposition of forced tolerance at any cost. It is extremely unfortunate that the mentioned and identified grotesque/situation, its tolerance on a global scale, lead to a misjudgement of the significance of real tumor inducers within the global health map//statistics as well as melanoma. The focus of prevention is being displaced, while the incidence of cancer in general and that of melanoma is skyrocketing. Nitrosamines could be defined as the newest, modern, until recently invisible and unknown, but -controllable form of genetic weapon to modify the human genome. Because of these very facts, the likelihood that clinicians and the academic community are in the frozen and permanent state of the Dunning-Kruger effect is very real. Certain globalization regulatory elements create problems and assignments that must be solved ˝competently˝ by incompetent, fully regulatable compartments. As their state of competence depends again and entirely on ˝their incompetence˝. Until now. After the formalization of the concept of Nitrosogenesis (as a form of genetic weapon) and melanoma for example, but not only, it remains to be seen whether universal incompetence will become a guarantee of competence and the survival. Or- will it remain again at the level of globalized, criminally conditioned, appointed and regulated from above "competent incompetence". The dilemmas to regulators and manufacturers remain open : Is it competent to take drugs that contain carcinogens/nitrosamines? Is it competent for this issue to continue for decades with impunity? Is it competent for regulators not to inform consumers about the presence of carcinogens/genome modifiers in medicines for decades? Is it competent for certain regions to be affected by nitrosamine contamination and not others? Is it competent not to reflect this in regional and global health bulletins on side effects? Is it competent to make thousands of times the profits from the modified genetic map business, regulated and legally initiated through the intake of carcinogens? Is it competent to have the concentration of carcinogens within polymedication exceeding many times the daily allowable doses of carcinogens and have no solution for this? Is it competent, when the intake of nitrosamines in medicines is associated with the generation of melanomas and heterogeneous cancers- to have no alternative to this or when one is available- to conceal it skillfully? Is it competent to determine carcinogenic activity based on mutagenic tests? Is it competent to be polyincompetent within a framework of mass (in)competence? We report systemically administered drugs for the treatment of high blood pressure from the group of beta blockers (bisoprolol/nebivolol) and ACE inhibitors (perindopril) that have been identified by regulators in the face of FDA as hypothetically contaminated with nitrosamines/NDSRIs with a carcinogenic potency between 4 and 5, respectively. Within this cumulative intake, (which according to the regulators was not at risk of developing cancerous forms), similar to other cases in the world literature, the patient developed a relatively short-term, metastatic nevus spilus-based nodular melanoma. The paper analyses not only the role of nitrosogenesis, but also that of two pregnancies and painful sunburns as potential cofactors for melanoma genesis. Academic attention is drawn to the potential impact of drug-mediated nitrosogenesis/carcinogenesis. Nitrosamines in the framework of polycontamination and polymedication could also be identified as one of the most effective, until recently unknown, modern generation genetic weapons for modifying the human genome and controlling cancer. Moreover, they could be controllably applied and skillfully targeted. At least until now. The officialization of carcinogens in more than 250 of the most common drugs and the clinico-pathological correlations concerning the development of cancer/melanoma in poorly controlled geographical regions represent a kind of in vivo prospective study to determine precisely the real carcinogenic role of nitrosamines to date.

From cultivation to cancer: formation of N-nitrosamines and other carcinogens in smokeless tobacco and their mutagenic implications.

Tobacco use is a major cause of preventable morbidity and mortality globally. Tobacco products, including smokeless tobacco (ST), generally contain tobacco-specific N-nitrosamines (TSNAs), such as N'-nitrosonornicotine (NNN) and 4-(methylnitrosamino)-1-(3-pyridyl)-butanone (NNK), which are potent carcinogens that cause mutations in critical genes in human DNA. This review covers the series of biochemical and chemical transformations, related to TSNAs, leading from tobacco cultivation to cancer initiation. A key aim of this review is to provide a greater understanding of TSNAs: their precursors, the microbial and chemical mechanisms that contribute to their formation in ST, their mutagenicity leading to cancer due to ST use, and potential means of lowering TSNA levels in tobacco products. TSNAs are not present in harvested tobacco but can form due to nitrosating agents reacting with tobacco alkaloids present in tobacco during certain types of curing. TSNAs can also form during or following ST production when certain microorganisms perform nitrate metabolism, with dissimilatory nitrate reductases converting nitrate to nitrite that is then released into tobacco and reacts chemically with tobacco alkaloids. When ST usage occurs, TSNAs are absorbed and metabolized to reactive compounds that form DNA adducts leading to mutations in critical target genes, including the RAS oncogenes and the p53 tumor suppressor gene. DNA repair mechanisms remove most adducts induced by carcinogens, thus preventing many but not all mutations. Lastly, because TSNAs and other agents cause cancer, previously documented strategies for lowering their levels in ST products are discussed, including using tobacco with lower nornicotine levels, pasteurization and other means of eliminating microorganisms, omitting fermentation and fire-curing, refrigerating ST products, and including nitrite scavenging chemicals as ST ingredients.