The Central Role of Cytochrome P450 in Xenobiotic Metabolism-A Brief Review on a Fascinating Enzyme Family

Human Cytochrome P450 (CYP) enzymes constitute a superfamily of membrane-bound hemoproteins that are responsible for the metabolism of a wide variety of clinically, physiologically, and toxicologically important compounds. These heme-thiolate monooxygenases play a pivotal role in the detoxification of xenobiotics, participating in the metabolism of many structurally diverge compounds. This short-review is intended to provide a summary on the major roles of CYPs in Phase I xenobiotic metabolism. The manuscript is focused on eight main topics that include the most relevant aspects of past and current CYP research. Initially, (I) a general overview of the main aspects of absorption, distribution, metabolism, and excretion (ADME) of xenobiotics are presented. This is followed by (II) a background overview on major achievements in the past of the CYP research field. (III) Classification and nomenclature of CYPs is briefly reviewed, followed by (IV) a summary description on CYP’s location and function in mammals. Subsequently, (V) the physiological relevance of CYP as the cornerstone of Phase I xenobiotic metabolism is highlighted, followed by (VI) reviewing both genetic determinants and (VI) nongenetic factors in CYP function and activity. The last topic of the review (VIII) is focused on the current challenges of the CYP research field.

Association between oral microflora and gastrointestinal tumors (Review)

The oral cavity contains the highest density and the most species of microorganisms compared with other parts of the body. Recent studies have determined that the species and abundance of oral microflora are closely associated with the development of upper gastrointestinal tumors, including oral, esophageal and gastric cancer. Additionally, differential abundant microbiota in patients with cancer and abnormal microorganisms inside the tumor tissue have been identified as critical markers of tumorigenesis. There is evidence to suggest that certain genera, including Firmicutes, along with various species, such as Porphyromonas, can increase the risk of oral cancer. Furthermore, Porphyromonas gingivalis is a risk factor for esophageal carcinoma, while Helicobacter pylori infections are a main cause of gastric cancer. Currently, as far as carcinogenic mechanisms of oral microorganisms are concerned, it has been hypothesized that the production of carcinogenic substances, chronic inflammation and altered cell metabolisms may be mechanisms by which oral microorganisms influence the development of upper gastrointestinal cancer. Certain phrases, including 'oral microbes', 'oral microorganism', 'oral microbiology', 'oral microflora', 'oral cancer', 'oral carcinoma', 'carcinoma of mouth', 'esophagus cancer', 'esophageal cancer', 'esophageal carcinoma', 'carcinoma of esophagus', 'gastric cancer', 'gastric carcinoma', 'stomach cancer', 'cancer of the stomach', 'carcinogenic mechanism' and 'carcinogenesis', were searched as key words in PubMed and Web of Science for articles published between 1975 to 2020. A total of 1,512 studies were obtained. After further searching the abstracts for key words, such as oral microorganisms, oral cancer, esophagus cancer, gastric cancer and carcinogenic mechanisms, 137 studies were selected. The current review systematically and comprehensively summarized the association between the oral microbiota and oral, esophageal and gastric cancer. Additionally, the current review described the carcinogenic mechanisms of oral microbes and attempted to identify common molecular mechanisms among different types of tumor. The association between upper gastrointestinal cancer therapy and oral microflora was also assessed. The present review may be used as a reference for future diagnosis and therapeutics for upper gastrointestinal tumors.

Review of aluminum, paraben, and sulfate product disclaimers on personal care products

BACKGROUND

Product disclaimers listed on personal care products face limited regulation. These disclaimers may be helpful or may mislead the public.

OBJECTIVE

Review the evidence supporting the potential harms of three compounds commonly addressed by product disclaimers: parabens, aluminum, and sulfates.

METHODS

Reported cases of adverse events to these compounds were identified. Trends in allergic contact dermatitis to chemicals used in place of these compounds were also identified.

RESULTS

There is limited evidence that parabens and aluminum pose a threat to human health; there is even less evidence that topical sulfate containing products pose a danger to consumers. In the setting of paraben avoidence, there has been a steady increase in cases of allergic contact dermatitis to preservatives which are more allergenic, specifically the isothiazolinones.

LIMITATIONS

Assessment of the toxicology of these compounds is ongoing and may change with new data.

CONCLUSION

There is limited evidence that parabens, aluminum, and sulfates used in personal care products pose a health risk. There is evidence that avoidance of parabens has resulted in an epidemic of allergic contact dermatitis to isothiazolonine preservatives.

Why We Will Continue to Lose Our Battle with Cancers If We Do Not Stop Their Triggers from Environmental Pollution

Besides our current health concerns due to COVID-19, cancer is a longer-lasting and even more dramatic pandemic that affects almost a third of the human population worldwide. Most of the emphasis on its causes has been posed on genetic predisposition, chance, and wrong lifestyles (mainly, obesity and smoking). Moreover, our medical weapons against cancers have not improved too much during the last century, although research is in progress. Once diagnosed with a malignant tumour, we still rely on surgery, radiotherapy, and chemotherapy. The main problem is that we have focused on fighting a difficult battle instead of preventing it by controlling its triggers. Quite the opposite, our knowledge of the links between environmental pollution and cancer has surged from the 1980s. Carcinogens in water, air, and soil have continued to accumulate disproportionally and grow in number and dose, bringing us to today's carnage. Here, a synthesis and critical review of the state of the knowledge of the links between cancer and environmental pollution in the three environmental compartments is provided, research gaps are briefly discussed, and some future directions are indicated. New evidence suggests that it is relevant to take into account not only the dose but also the time when we are exposed to carcinogens. The review ends by stressing that more dedication should be put into studying the environmental causes of cancers to prevent and avoid curing them, that the precautionary approach towards environmental pollutants must be much more reactionary, and that there is an urgent need to leave behind the outdated petrochemical-based industry and goods production.

Implications of Lifestyle and Occupational Factors on the Risk of Breast Cancer in Shiftwork Nurses

Shift work that involves circadian disruption has been highlighted as a likely carcinogenic factor for breast cancer in humans. Also, unhealthy lifestyle habits observed in night work nurses could be causally related to an increase in the incidence of estrogen-positive breast tumours in this population. Assessing baseline risk of breast cancer in nurses is essential. The objective of this study was to analyze the risk of breast cancer that nurses had in relation to their lifestyle and labour factors related to shift work. A cross-sectional descriptive study through a questionnaire about sociodemographic variables, self-perception of health, and working life was designed. The sample consisted of 966 nurses. The relationship between variables was tested. A binary logistic regression and a classification and regression tree were performed. The most significant labour variables in relation to the risk of breast cancer were the number of years worked (more than 16 years; p < 0.01; OR = 8.733, 95% CI = 2.811, 27.134) and the total years performing more than 3 nights per month (10 or more years; p < 0.05; OR = 2.294, 95% CI = 1.008, 5.220). Also, the nights worked throughout life (over 500; OR = 4.190, 95% CI = 2.118, 8.287) were significant in the analysis. Nurses who had or ever had breast cancer valued their self-perceived health more negatively (p < 0.001) and referred a lower quality of sleep (p < 0.001) than the non-cases nurses. The occupational factors derived from night work could have several impacts on nurses' health and their family-work balance. Promoting healthy lifestyles, informing about shift work risks, and adjusting shift work schedules are critical methods to decrease the possible effects of circadian disruption in nurses.

Electrical features, liquid composition and toxicant emissions from 'pod-mod'-like disposable electronic cigarettes

INTRODUCTION

Use of flavoured pod-mod-like disposable electronic cigarettes (e-cigarettes) has grown rapidly, particularly among cost-sensitive youth and young adults. To date, little is known about their design characteristics and toxicant emissions. In this study, we analysed the electrical and chemical characteristics and nicotine and pulmonary toxicant emission profiles of five commonly available flavoured disposable e-cigarettes and compared these data with those of a JUUL, a cartridge-based e-cigarette device that pod-mod-like disposables emulate in size and shape.

METHODS

Device construction, electrical power and liquid composition were determined. Machine-generated aerosol emissions including particulate matter, nicotine, carbonyl compounds and heavy metals were also measured. Liquid and aerosol composition were measured by high-performance liquid chromatography, gas chromatography-mass spectrometry/flame ionisation detection, and inductively coupled plasma mass spectrometry.

RESULTS

We found that unlike JUUL, disposable devices did not incorporate a microcontroller to regulate electrical power to the heating coil. Quality of construction varied widely. Disposable e-cigarette power ranged between 5 and 9 W and liquid nicotine concentration ranged between 53 and 85 mg/mL (~95% in the protonated form). In 15 puffs, total nicotine yield for the disposables ranged between 1.6 and 6.7 mg, total carbonyls ranged between 28 and 138 µg, and total metals ranged between 1084 and 5804 ng. JUUL emissions were near the floors of all of these ranges.

CONCLUSIONS

Disposable e-cigarettes are designed with high nicotine concentration liquids and are capable of emitting much higher nicotine and carbonyl species relative to rechargeable look-alike e-cigarettes. These differences are likely due to the lower quality in construction, unreliable labelling and lack of temperature control regulation that limits the power during operation. From a public health perspective, regulating these devices is important to limit user exposure to carbonyls and nicotine, particularly because these devices are popular with youth and young adults.

Exploring Potential Carcinogenic Activity of Per- and Polyfluorinated Alkyl Substances Utilizing High-Throughput Toxicity Screening Data

Per- and polyfluorinated alkyl substances (PFAS) are ubiquitous, persistent, and toxic chemicals that pose public health risks. Recent carcinogenicity concerns have arisen based on epidemiological studies, animal tumor findings, and mechanistic data. Thousands of PFAS exist; however, current understanding of their toxicity is informed by studies of a select few, namely, perfluorooctanoic acid and perfluorooctanesulfonic acid. Hence, the computational, high-throughput screening tool, the US EPA CompTox Chemical Dashboard's ToxCast, was utilized to explore the carcinogenicity potential of PFAS. Twenty-three major PFAS that had sufficient in vitro ToxCast data and covered a range of structural subclasses were analyzed with the visual analytics software ToxPi, yielding a qualitative and quantitative assessment of PFAS activity in realms closely linked with carcinogenicity. A comprehensive literature search was also conducted to check the consistency of analyses with other mechanistic data streams. The PFAS were found to induce a vast range of biological perturbations, in line with several of the International Agency for Research on Cancer-defined key carcinogen characteristics. Patterns observed varied by length of fluorine-bonded chains and/or functional group within and between each key characteristic, suggesting some structure-based variability in activity. In general, the major conclusions drawn from the analysis, that is, the most notable activities being modulation of receptor-mediated effects and induction of oxidative stress, were supported by literature findings. The study helps enhance understanding of the mechanistic pathways that underlie the potential carcinogenicity of various PFAS and hence could assist in hazard identification and risk assessment for this emerging and relevant class of environmental toxicants.

Detecting Chemical Vapor Diffusion through Firefighter Turnout Gear

Firefighters are exposed to burning materials that may release toxic partial combustion and pyrolysis products into the environment, including compounds listed as priority pollutants by the United States Environmental Protection Agency (EPA). A novel passive sampling dosimeter device containing firefighter turnout gear as a diffusion membrane and an activated charcoal strip (ACS) for volatile analyte collection was designed and used to monitor potential exposures of firefighters to volatile organic compounds. Solvent extracts from the ACS and turnout gear diffusion layer were analyzed using Gas Chromatography–Mass Spectrometry (GC-MS) to determine the diffusion of compounds from burned substrates through firefighter turnout gear and compound adsorption to the turnout gear. The compounds in these samples were identified using target factor analysis (TFA). An activated carbon layer (ACL) was added to the dosimeter between the turnout gear and the ACS. The presence of combustion and pyrolysis compounds identified on the ACS in the dosimeter was reduced.

Cancer Incidence and Mortality among Firefighters: An Overview of Epidemiologic Systematic Reviews

Firefighters are exposed to carcinogens that may increase their risk of developing many types of occupational cancer. Many systematic reviews (SRs) have been produced with sometimes conflicting conclusions. In this overview of reviews, we aim to assess the conclusion consistency across the available systematic reviews on the cancer risk in firefighters. Literature searches were conducted in several indexed databases and grey literature to retrieve systematic reviews aiming to evaluate cancer incidence or cancer mortality in firefighters. Results from included SRs were analyzed according to the tumour site. Out of 1054 records identified by the search in the databases, a total of 11 SRs were ultimately included. The original studies (n = 104) analyzed in the SRs were published between 1959 and 2018. The results consistently reported a significant increase in the incidence of rectal, prostate, bladder and testicular cancers as well as mesothelioma and malignant melanoma in firefighters compared to the general population. The SRs also indicate that death rates from rectal cancer and non-Hodgkin's lymphoma are higher among firefighters. Consistent SR results suggest that several types of cancer may be more frequent in firefighters than in the general population.

Supervised mutational signatures for obesity and other tissue-specific etiological factors in cancer

Determining the etiologic basis of the mutations that are responsible for cancer is one of the fundamental challenges in modern cancer research. Different mutational processes induce different types of DNA mutations, providing 'mutational signatures' that have led to key insights into cancer etiology. The most widely used signatures for assessing genomic data are based on unsupervised patterns that are then retrospectively correlated with certain features of cancer. We show here that supervised machine-learning techniques can identify signatures, called SuperSigs, that are more predictive than those currently available. Surprisingly, we found that aging yields different SuperSigs in different tissues, and the same is true for environmental exposures. We were able to discover SuperSigs associated with obesity, the most important lifestyle factor contributing to cancer in Western populations.

Deciphering the Influence of Cigarette Smoke Carcinogens on CNS Associated Biomolecules: A Computational Synergistic Approach

BACKGROUND

Human health issues caused by Cigarette Smoke Carcinogens (CSC) are increasing rapidly every day and challenging the scientific community to provide a better understanding in order to avoid its impact on communities. Cigarette smoke also contains tobacco-based chemical compounds harmful to human beings, either smokers or non-smokers.

OBJECTIVE

We have tested 7H-Dibenzo[c,g]carbazole (7H-DBC) and Dibenz[a,h]acridine (DBAD) derivatives of Asz-arenes along with N'-Nitrosoanabasine (NAB) and N-Nitrosoanatabine (NAT) derivatives of N-Nitrosamines molecular interaction with CNS biomolecules.

METHODS

Computational synergistic approaches like system biology and molecular interaction techniques were implemented to conduct the analysis.

RESULTS

CSC efficiently interacted with NRAS, KRAS, CDH1, and RAC1 molecular targets in CNS. We have also performed the interactome analysis followed by system biology approaches and found that HSPA8 is the most important hub protein for the network generated for CSC-hampered genes of CNS. We have also identified 6 connector proteins, namely TP53, HSP90AA1, PPP2CA, CDH1, CTNNB1, and ARRB1. Further analysis revealed that NRAS and CDH1 have maximum interactions with all the selected CSC.

CONCLUSION

The obtained structural analysis data could be utilized to assess the carcinogenic effect of CSC and could be useful in the treatment of CNS diseases and disorders induced, especially by tobacco-specific carcinogens, or it could also be used in vivo/ in vitro experimentation model designing.

[Determination of 1-chloro-2,3-epoxypropane in order to assess the working environment]

BACKGROUND

1-Chloro-2,3-epoxypropane, known as epichlorohydrin (ECH), is a colorless liquid used in the production of epoxy resins, synthetic glycerine, elastomers, glycidyl ethers, surfactants, polyamide-epichlorohydrin resins and others. Epichlorohydrin may cause cancer. The aim of this study was to develop a new method for determining concentrations of ECH in workplace air in the range of 1/10-2 values of the maximum admissible concentration (MAC).

MATERIAL AND METHODS

The paper presents a method for the determination of ECH in workplace air using a gas chromatograph coupled with a mass spectrometer (GC-MS). The developed method is based on the adsorption of ECH on an activated charcoal, extraction with acetone, and a chromatographic analysis of the resulting solution.

RESULTS

The method developed makes it possible to determine ECH in the concentration range of 0.1-2 mg/m³, i.e., 1/10-2 values of MAC established in Poland. The limit of detection (LOD) is 0.24 μg/m³ and the limit of quantification (LOQ) is 0.71 μg/m³.

CONCLUSIONS

The method is characterized by good precision and accuracy; it meets the requirements of the European standard PN-EN 482, and can be used by occupational hygiene laboratories to measure concentrations of ECH in workplace air, with a view to assessing workers' exposure to this substance. Med Pr. 2020;71(6):715-23.

Neoplastic diseases (cancer) of occupational origine between 2003-2019 in Podkarpackie voivodeship

INTRODUCTION

In Europe data concerned with occupational exposure to carcinogens or mutagenic factors is collected on the basis of: national registers, databases and information systems related to the exposure, and presenting the degree of health hazard for the employees who are exposed to such factors. The overriding carcinogenic factors at workplace, which are essential for preventive measures against occupational diseases used by institutions responsible for occupational safety, are e.g.: asbestos, polycyclic aromatic hydrocarbons, arsenic trichloroethylene, tetrachloroethylene and industrial processes related to exposure to wood dust.

AIM OF THE PAPER

The paper shows current data relating to cancers of occupational origin in Podkarpackie voivodeship between 2003-2019.

MATERIAL AND METHODS

The materials coming from Podkarpackie voivodeship between 2003-2019 are collected occupational diseases identification cards, sent to the Podkarpacki National Provincial Sanitary Inspectorate by Sanitary Inspectors of Podkarpackie voivodeship districts.

RESULTS

Between 2003 - 2019 in Podkarpackie voivodeship neoplastic diseases made up 1,94% of a total of all occupational diseases. Since 2006 the frequency of the occupational cancers stays at similar level. The most frequent locations of neoplastic diseases of occupational etiology were: lungs, bronchi and larynx.

CONCLUSIONS

Occupational cancer can be prevented by elimination or limitation of occupational exposition to carcinogenic or mutagenic substances, regular monitoring of their intensity in work environment, providing workers with individual protection by employers, preventive measures taken by occupational health service, occupational safety and health as well as supervising institutions such as National Sanitary Inspectorate and State Labour Inspectorate.

The Nightingale Legacy

The World Health Organization (WHO, 2020) has designated 2020 as the International Year of the Nurse and the Midwife to mark the 200th anniversary of Florence Nightingale's birth. This celebration honors her work and impact on the nursing profession-one of engagement and advocacy for public health. Nightingale's Notes on Nursing (1860) illustrated her observations of social determinants for health wellness and illness. She championed efforts for community access to clean water and public sanitization and emphasized the importance of nutrition and hygiene on healing and wellness. Her calls for action still resonate with enduring worldwide healthcare shortcomings, which contribute significantly to morbidity and mortality.

Environmental Risk Factors: The role of oncology nurses in assessing and reducing the risk for exposure

BACKGROUND

The multifaceted origins of cancer are related to the dynamic interface between the human body and the environment. It is estimated that as many as 60% of cancers arise from environmental exposures.

OBJECTIVES

This article describes potential risks for exposure to radon, arsenic, pesticides, and antineoplastic agents, which can lead to the development of cancer.

METHODS

The authors performed a review of the literature on environmental exposures and their relationship to the development of cancer.

FINDINGS

Environmental factors are abundant in the home, workplace, and environment. Nurses can lead campaigns to educate the public about environmental risk factors and their effects on the development of cancer.

Arsenic Methyltransferase and Methylation of Inorganic Arsenic

Arsenic occurs naturally in the environment, and exists predominantly as inorganic arsenite (As (III) and arsenate As (V)). Arsenic contamination of drinking water has long been recognized as a major global health concern. Arsenic exposure causes changes in skin color and lesions, and more severe health conditions such as black foot disease as well as various cancers originating in the lungs, skin, and bladder. In order to efficiently metabolize and excrete arsenic, it is methylated to monomethylarsonic and dimethylarsinic acid. One single enzyme, arsenic methyltransferase (AS3MT) is responsible for generating both metabolites. AS3MT has been purified from several mammalian and nonmammalian species, and its mRNA sequences were determined from amino acid sequences. With the advent of genome technology, mRNA sequences of AS3MT have been predicted from many species throughout the animal kingdom. Horizontal gene transfer had been postulated for this gene through phylogenetic studies, which suggests the importance of this gene in appropriately handling arsenic exposures in various organisms. An altered ability to methylate arsenic is dependent on specific single nucleotide polymorphisms (SNPs) in AS3MT. Reduced AS3MT activity resulting in poor metabolism of iAs has been shown to reduce expression of the tumor suppressor gene, p16, which is a potential pathway in arsenic carcinogenesis. Arsenic is also known to induce oxidative stress in cells. However, the presence of antioxidant response elements (AREs) in the promoter sequences of AS3MT in several species does not correlate with the ability to methylate arsenic. ARE elements are known to bind NRF2 and induce antioxidant enzymes to combat oxidative stress. NRF2 may be partly responsible for the biotransformation of iAs and the generation of methylated arsenic species via AS3MT. In this article, arsenic metabolism, excretion, and toxicity, a discussion of the AS3MT gene and its evolutionary history, and DNA methylation resulting from arsenic exposure have been reviewed.

UDP-glucuronosyltransferase polymorphisms affect diethylnitrosamine-induced carcinogenesis in humanized transgenic mice

UDP‐glucuronosyltransferase (UGT) 1A enzymes detoxify a broad array of exogenous compounds including environmental toxins and carcinogens. Case‐control studies identified genetic variations in UGT1A genes leading to reduced glucuronidation activity, which were associated with hepatocellular carcinoma (HCC) formation and progression. The aim of the study was therefore to examine the direct effect of common UGT1A polymorphisms (SNPs) on HCC development and outcome in a diethylnitrosamine (DEN)‐induced mouse model. Therefore, a single intraperitoneal DEN injection (20 mg/kg) was administered to 15‐day‐old htgUGT1A‐WT and htgUGT1A‐SNP mice (containing a human haplotype of 10 common UGT1A SNPs) either receiving water or coffee cotreatment for the following 39 weeks. After this time, tumor incidence, size (>1 mm), histology, liver‐body ratio, serum aminotransferase activities, and UGT1A regulation and activity levels were determined. In DEN‐treated htgUGT1A‐SNP mice, a markedly higher number of tumors with a bigger cumulative diameter were detected. The relative liver weight and aminotransferase activity levels were also significantly higher in mice carrying UGT1A SNPs. After coffee + DEN cotreatment, susceptibility for tumor development and growth considerably decreased in both mouse lines, but was still higher in htgUGT1A‐SNP mice. In conclusion, our study provides experimental evidence for the protective role of UGT1A enzymes in neoplastic transformation. These data confirm case‐control studies implicating impaired UGT1A‐mediated carcinogen detoxification as a risk factor for individual cancer disposition. Coffee treatment, which is able to activate UGT1A expression and activity, reduced HCC development and provides an explanation for the protective properties of coffee on liver diseases including liver cancer.

Benefits of aged garlic extract in modulating toxicity biomarkers against p-dimethylaminoazobenzene and phenobarbital induced liver damage in Rattus norvegicus

Garlic (Allium sativum L.), a popular spice, has been used for decades in treating several medical conditions. Although Allicin, an active ingredient of garlic has been extensively studied on carcinogen-induced hepatotoxicity and oxidative stress in rats (Rattus norvegicus), no systematic study on the beneficial effects of generic aged garlic and specific aged garlic extract-Kyolic has been done. The present study involves rats fed chronically with two liver carcinogens, p-dimethylaminoazobenzene and phenobarbital, to produce hepatotoxicity. The aged garlic extract was characterized by UV-spectra, FTIR, HPLC and GC-MS. Biochemical and pathophysiological tests were performed by keeping suitable controls at four fixation intervals, namely, 30, 60, 90, and 120 days, utilizing several widely accepted toxicity biomarkers. Compared to the controls, remarkable elevation in the activities of lactate dehydrogenase, gamma glutamyl transferase and decline in catalase and glucose-6-phosphate dehydrogenase were observed in the carcinogen fed rats. Daily administration of aged garlic extract, could favorably modulate the elevated levels of various toxicity biomarkers including serum triglyceride, creatinine, urea, bilirubin, blood urea nitrogen except total cholesterol. It also altered the levels of blood glucose, HDL-cholesterol, albumin, AST, ALT, and hemoglobin contents in carcinogen intoxicated rats, indicating its protective potential against hepatotoxicity and oxidative stress in the experimental rats. Down-regulation of Bcl-2 and p53 proteins caused cell cycle arrest and apoptosis in garlic fed group. Kyolic exhibited additional benefits by arresting cell viability of cancer cells. This study would thus validate the use of aged garlic extract in the treatment of diseases causing liver toxicity including hepatocarcinoma.

Voltage and e-liquid composition affect nicotine deposition within the oral cavity and carbonyl formation

INTRODUCTION

The diversity of e-liquids along with higher powered e-cigarette nicotine delivery devices are increasing. This study evaluated the effect of voltage and e-liquid composition on particle size, nicotine deposition in a human oral-trachea cast model and generation of carbonyls.

METHODS

Nineteen e-liquids were evaluated for 30 common chemicals by gas chromatography-mass spectrometry (GC-MS). E-cigarette aerosols containing nicotine (1.2%) were generated at 4 and 5 volts for assessment of particle size distribution using Aerodynamic Particle Sizer (APS), Fast Mobility Particle Size (FMPS) and an In-Tox cascade impactor and nicotine deposition by GC-MS. Carbonyl formation in aerosols was assessed by liquid chromatography tandem triple-quad mass spectrometry.

RESULTS

Total chemical burden ranged from 0.35 to 14.6 mg/mL with ethyl maltol present in all e-liquids. Increasing voltage was associated with an increase in median size of aerosol particles and the deposition of nicotine in the oral cast. Two e-liquids caused a 2.5-fold to 5-fold increase in nicotine deposition independent of particle size and voltage. Increasing voltage caused an increase in formaldehyde, acetaldehyde and acrolein in the presence and absence of nicotine. Most striking, aerosols from several e-liquids significantly increased levels of acetaldehyde and acrolein compared with unflavoured.

CONCLUSIONS

Increasing voltage and composition of e-liquid can increase the exposure of the oral pharynx and bronchial airways to carbonyls that can react with DNA to generate adducts, induce oxidative stress, inflammation and cell death. The elevated nicotine and carbonyls readily enter the circulation where they can also cause cardiovascular stress. The growing popularity of higher voltage e-cigarette delivery devices will likely further elevate health risks from chronic exposure to these complex aerosols.

Might limiting liquid nicotine concentration result in more toxic electronic cigarette aerosols?

Some jurisdictions have instituted limits on electronic cigarette (ECIG) liquid nicotine concentration, in an effort to control ECIG nicotine yield, and others are considering following suit. Because ECIG nicotine yield is proportional to the product of liquid nicotine concentration (milligram per millilitre) and device power (watts) regulations that limit liquid nicotine concentration may drive users to adopt higher wattage devices to obtain a desired nicotine yield. In this study we investigated, under various hypothetical regulatory limits on ECIG liquid nicotine concentration, a scenario in which a user of a common ECIG device (SMOK TF-N2) seeks to obtain in 15 puffs the nicotine emissions equivalent to one combustible cigarette (ie, 1.8 mg). We measured total aerosol and carbonyl compound (CC) yields in 15 puffs as a function of power (15-80 W) while all else was held constant. The estimated nicotine concentration needed to achieve combustible cigarette-like nicotine yield at each power level was then computed based on the measured liquid consumption. We found that for a constant nicotine yield of 1.8 mg, reducing the liquid nicotine concentration resulted in greater amount of liquid aerosolised (p<0.01) and greater CC emissions (p<0.05). Thus, if users seek a given nicotine yield, regulatory limits on nicotine concentration may have the unintended consequence of increasing exposure to aerosol and respiratory toxicants. This outcome demonstrates that attempting to control ECIG nicotine yield by regulating one factor at a time may have unintended health effects and highlights the need to consider multiple factors and outcomes simultaneously when designing regulations.

Identification of volatile constituents released from IQOS heat-not-burn tobacco HeatSticks using a direct sampling method

OBJECTIVES

To identify the chemicals released in I Quit Ordinary Smoking (IQOS) heat-not-burn tobacco aerosol and to assess their potential human health toxicity.

METHODS

The heating temperature window of the IQOS heat-not-burn device was determined using a thermographic camera over a period of 100 s. Qualitative studies were performed using a novel real-time gas chromatograph-mass spectrometer set-up. Aerosols from six tobacco-flavoured IQOS HeatSticks (Amber, Blue, Bronze, Sienna, Turquoise and Yellow) were collected in a 1 mL loop via a manual syringe attached to the sample-out port of the valve. The gas transport line was heated to 200°C in order to prevent the condensation of volatile species. Compound identification was performed using the NIST11 mass spectrometry database library (US National Institute of Standards and Technology), where only chemicals with a match of 70% and above were listed as identifiable.

RESULTS

The temperature profile of the IQOS device revealed a non-combustive process employed in generating the tobacco aerosol. Real-time qualitative analysis revealed 62 compounds encompassing a broad spectrum of chemicals such as carbonyls, furans and phthalates, which are highly toxic.

DISCUSSION

Our findings complement the qualitative studies previously performed by Philip Morris International and others via indirect sampling methods. By analysing the aerosols in real time, we have identified a total of 62 compounds, from which only 10 were in common with previous studies. Several identified species such as diacetyl, 2,3-pentanedione, hydroxymethylfurfural and diethylhexyl phthalate are classified as highly toxic, with the latter considered carcinogenic.

CYP1B1 gene: Implications in glaucoma and cancer

Glaucoma is a serious disease that can lead to irreversible loss of vision. Patients with primary congenital glaucoma may have elevated intraocular pressure. Hypertension causes damages to intraocular structures and affects the Schlemm's canal, collector channels, trabecular meshwork, and optic nerve's molecular structures. An important gene that is defective in patients with glaucoma is CYP1B1, a gene associated with optic nerve deterioration. CYP1B1is a key enzyme involved in the metabolism of exogenous and endogenous compounds. Also, it is critical in the detoxification of pre-carcinogens, such as polycyclic aromatic hydrocarbons and estrogen. It catalyzes their conversion into metabolites subsequently eliminated from the body. In malignant tumors, the CYP1B1 promoter is hypomethylated. CYP1B1 overexpression results in the conversion of estrogens to quinone forms, which bind with DNA and create a predisposition for cancer in several organs, such as the brain, breast, and ovary. Increased cytokine interleukin-6 and leptin lead to elevated CYP1B1 activity, which possibly causes cancer. In addition, the expression of aromatic hydrocarbon receptors is increased in tumor tissues, and it elevates oxidative stress and cell growth. TCGA database analysis showed increased survival at bladder and renal carcinoma when CYP1B1 expression is low. Therefore, alteration of CYP1B1 expression may suggest a therapeutic benefit for multiple diseases such as glaucoma and cancer.

Increased Thyroid Cancer Incidence in Volcanic Areas: A Role of Increased Heavy Metals in the Environment?

Thyroid cancer incidence is significantly increased in volcanic areas, where relevant non-anthropogenic pollution with heavy metals is present in the environment. This review will discuss whether chronic lifelong exposure to slightly increased levels of metals can contribute to the increase in thyroid cancer in the residents of a volcanic area. The influence of metals on living cells depends on the physicochemical properties of the metals and their interaction with the target cell metallostasis network, which includes transporters, intracellular binding proteins, and metal-responsive elements. Very little is known about the carcinogenic potential of slightly increased metal levels on the thyroid, which might be more sensitive to mutagenic damage because of its unique biology related to iodine, which is a very reactive and strongly oxidizing agent. Different mechanisms could explain the specific carcinogenic effect of borderline/high environmental levels of metals on the thyroid, including (a) hormesis, the nonlinear response to chemicals causing important biological effects at low concentrations; (b) metal accumulation in the thyroid relative to other tissues; and (c) the specific effects of a mixture of different metals. Recent evidence related to all of these mechanisms is now available, and the data are compatible with a cause–effect relationship between increased metal levels in the environment and an increase in thyroid cancer incidence.

Tissue-Specific Carcinogens as Soil to Seed BRCA1/2-Mutant Hereditary Cancers

Despite their ubiquitous expression, the inheritance of monoallelic germline mutations in breast cancer susceptibility gene type 1 or 2 (BRCA1/2) poses tissue-specific variations in cancer risks and primarily associate with familial breast and ovarian cancers. The molecular basis of this tissue-specific tumor incidence remains unknown and intriguing to cancer researchers. A plethora of recent reports support the idea that several nongenetic factors present in the tissue microenvironment could induce tumors in the mutant BRCA1/2 background. This Opinion article summarizes the recent advances on tissue-specific carcinogens and their complex crosstalk with the compromised DNA repair machinery of BRCA1/2-mutant cells. Finally, we present our perspective on the therapeutic and chemopreventive interpretations of these developments.