Polycyclic aromatic hydrocarbons and digestive tract cancers: a perspective

Relationship Between Polycyclic Aromatic Hydrocarbons and Cardiovascular Diseases: A Systematic Review

Objective: The primary aim of this systematic review was to examine the relationship of polycyclic aromatic hydrocarbon (PAH) exposure with cardiovascular diseases (CVDs) and elaborate the current knowledge and recent advances in the area of PAH and its effects on CVDs and discuss the growing epidemiological evidence linking PAH to CVDs on the health of human populations. In this systematic review, the increased risk of cardiovascular diseases and their relationship with PAHs were discussed in detail.

Methods: On 05th April 2021, a systematic literature search was conducted using PubMed/Medline and Web of Science search engines in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria. The search was limited to articles that were written in English and dealt with human issues. All original peer-review publications were considered for inclusion. Comments, case reports, reviews, duplicated papers, and conference reports were excluded. Data was collected from included papers by two independent reviewers.

Results: Conclusively, 20 research articles published between 2005 and 2021 were chosen for the final analysis. The systemic review included 20 studies with a variety of geographical studies. The most common research category among the nominated studies were time-series studies followed by retrospective cohort, cross-sectional, quasi-experimental, panel, and case-control studies. Most of the studies were conducted in the United States, whereas others were showed in various geographical countries around the world, such as Denmark, Germany, Finland, Netherlands, France, China, Norway, Korea, Sweden, Saudi Arabia, and Belgium. Eight studies assessed the association between PAH exposure and CVDs, four articles observed this relationship with blood pressure (BP), two observed association between atherosclerotic CVD and PAH, one congenital heart disease, cardiovascular events, and two with obesity. Furthermore, in some investigations, a favorable association between PAH exposure and hypertension as well as PAH exposure and obesity was found.

Conclusion: In conclusion, this systematic review examined the relationship of PAH exposure with CVDs and CVD-related risk factors by searching several digital databases. After a comprehensive literature searches and summarizing findings from 20 articles, the authors concluded that a positive relationship was observed between PAH exposure and CVD risks.

PIG-A gene mutation as a genotoxicity biomaker in polycyclic aromatic hydrocarbon-exposed barbecue workers

Background

The PIG-A gene mutation assay is a valuable tool for measuring in vivo gene mutations in blood cells. The human PIG-A assay, used as a potential genotoxicity biomarker, is minimally invasive, sensitive, and cost-efficient; however, the relationship between carcinogen exposure and PIG-A mutations is not well understood.

Methods

We investigated the genotoxic effect of red blood cells using PIG-A assay and lymphocyte cytokinesis-block micronucleus test in barbecue restaurant workers (N = 70) exposed to polycyclic aromatic hydrocarbons (PAHs) and self-identified healthy control subjects (N = 56). Urinary PAH metabolites were measured to evaluate internal exposure levels.

Results

Multivariate Poisson regression showed that the PAH-exposed workers exhibited significantly higher PIG-A mutant frequency (MF) (8.04 ± 6.81 × 10^− 6) than did the controls (5.56 ± 5.26 × 10^− 6) (RR = 0.707, 95% CI: 0.615–0.812, P < 0.001). These results indicate that PAH exposure is a risk factor for elevated PIG-A MF. The frequencies of micronuclei (MN) and nuclear buds (NBUD) in the PAH-exposed workers (MN: 3.06 ± 2.07 ‰, NBUD: 1.38 ± 1.02 ‰) were also significantly higher than in the controls (MN: 1.46 ± 0.64 ‰, P < 0.001; NBUD: 0.70 ± 0.60 ‰, P < 0.001). Additionally, PIG-A MFs showed better associations with several urinary hydroxylated PAH metabolites (P_2-OH-Flu = 0.032, r_2-OH-Flu = 0. 268; P_2-OH-Phe = 0.022, r_2-OH-Phe = 0.286; P_3-OH-Phe = 0.0312, r_3-OH-Phe = 0.270; P_4-OH-Phe = 0.018, r_4-OH-Phe = 0.296), while the increase in MN, NPB, and NBUD frequencies was not associated with any OH-PAH metabolites; and high-PAH-exposed workers showed the highest PIG-A MFs. Furthermore, there was a significant association between PIG-A MF and PAH exposure levels (Chi-square test for trend, P = 0.006).

Conclusions

Our results indicate that an increase in PIG-A MF in barbecue workers could reflect the response to PAH exposure, providing evidence of its potential as a genotoxicity biomarker in human risk assessment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s41021-021-00230-1.

Evaluation of Carcinogenic Polyaromatic Hydrocarbon Levels in Airborne Particulates Associated with Long-Term Exposure throughout the COVID-19 Pandemic in Makkah, Saudi Arabia

BACKGROUND

The effect of polyaromatic hydrocarbons (PAHs) on human health differs depending on the duration and exposure path.

OBJECTIVE

This study aimed to examine the effects of PAHs on the human health risks associated with long-term exposure both before and throughout the COVID-19 pandemic.

METHODOLOGY

PM10 sampling for 24 h was conducted at six sampling sites (Al-Haram, Aziziyah, Al Nuzhah, Muzdalifah, Arafat, and Al Awali). On-site measurements were conducted from March 2020 to February 2021. PAHs were analyzed using Perkin Elmer GC/MS, which was adjusted with standard reagents for identifying 16 PAH mixtures.

RESULTS

The 24 h average PM10 concentration showed considerable inconsistencies, exceeding the WHO standards used for median exposure (25.0 µgm-3). The PAH intensities fluctuated from 7.67 to 34.7 ng/m3 in a suburban area, near a rush-hour traffic road, and from 6.34 to 37.4 ng/m3 close to business and light manufacturing areas. The highest carcinogenic compound levels were found in the Al-Azizia, Al Muzdalifah, and Al Nuzah areas because of the high traffic density, and the lowest concentrations were found in the Al-Haram and Arafat areas throughout the year, as a result of the COVID-19 pandemic health precautions that were undertaken by the government of Saudi Arabia involving border entry limits and limitations of the Umrah and Hajj seasons.

CONCLUSION

This study period is considered extraordinary as the Saudi Arabian government has undertaken successful preventive measures that have had a great effect both on the spread of the pandemic and in reducing air pollution in Makkah. More studies are required to examine PAHs' carcinogenic effects after the pandemic measures are eased across Makkah.

Polycyclic Aromatic Hydrocarbons Detected in Processed Meats Cause Genetic Changes in Colorectal Cancers

Polycyclic aromatic hydrocarbons (PAHs) are commonly ingested via meat and are produced from high-temperature cooking of meat. Some of these PAHs have potential roles in carcinogenesis of colorectal cancer (CRC). We aimed to investigate PAH concentrations in eight types of commonly consumed ready-to-eat meat samples and their potential effects on gene expressions related to CRC. Extraction and clean-up of meat samples were performed using QuEChERS method, and PAHs were detected using GC-MS. Nine different PAHs were found in meat samples. Interestingly, roast turkey contained the highest total PAH content, followed by salami meat. Hams of varying levels of smokedness showed a proportional increase of phenanthrene (PHEN), anthracene (ANTH), and fluorene (FLU). Triple-smoked ham samples showed significantly higher levels of these PAHs compared to single-smoked ham. These three PAHs plus benzo[a]pyrene (B[a]P), being detected in three meat samples, were chosen as treatments to investigate in vitro gene expression changes in human colon cells. After PAH treatment, total RNA was extracted and rtPCR was performed, investigating gene expression related to CRC. B[a]P decreased mRNA expression of TP53. In addition, at high concentrations, B[a]P significantly increased KRAS expression. Treatments with 1 µM PHEN, 25 µM, and 10 µM FLU significantly increased KRAS mRNA expression in vitro, implying the potential basis for PAH-induced colorectal carcinogenesis. Opposingly, the ANTH treatment led to increased TP53 and APC expression and decreased KRAS expression, suggesting an anti-carcinogenic effect. To conclude, PAHs are common in ready-to-eat meat samples and are capable of significantly modifying the expression of key genes related to CRC.

E-waste polycyclic aromatic hydrocarbon (PAH) exposure leads to child gut-mucosal inflammation and adaptive immune response

Polycyclic aromatic hydrocarbon (PAH) exposure alters immunological responses. Research concerning PAH exposure on intestinal immunity of children in electronic waste (e-waste) areas is scarce. The aim of this study was to evaluate the effects of polycyclic aromatic hydrocarbon (PAH) pollutants on intestinal mucosal immunity of children in e-waste areas. Results showed higher hydroxylated PAH (OH-PAH) concentrations in e-waste-exposed children, accompanied with higher sialyl Lewis A (SLA) level, absolute lymphocyte and monocyte counts, decreased of percentage of CD4⁺ T cells, and had a higher risk of diarrhea. OH-PAH concentrations were negative with child growth. 1-OHNap mediated through WBCs, along with 1-OHPyr, was correlated with an increase SLA concentration. 2-OHFlu, 1-OHPhe, 2-OHPhe, 1-OHPyr, and 6-OHChr were positively correlated with secretory immunoglobulin A (sIgA) concentration. Our results indicated that PAH pollutants caused inflammation, affected the intestinal epithelium, and led to transformation of microfold cell (M cell). M cells initiating mucosal immune responses and the subsequent increasing sIgA production might be an adaptive immune respond of children in the e-waste areas. To our knowledge, this is the first study of PAH exposure on children intestinal immunity in e-waste area, showing that PAH exposure plays a negative role in child growth and impairs the intestinal immune function.

Evaluation of fireground exposures using urinary PAH metabolites

BACKGROUND

Firefighters have increased cancer incidence and mortality rates compared to the general population, and are exposed to multiple products of combustion including known and suspected carcinogens.

OBJECTIVE

The study objective was to quantify fire response exposures by role and self-reported exposure risks.

METHODS

Urinary hydroxylated metabolites of polycyclic aromatic hydrocarbons (PAH-OHs) were measured at baseline and 2-4 h after structural fires and post-fire surveys were collected.

RESULTS

Baseline urine samples were collected from 242 firefighters. Of these, 141 responded to at least one of 15 structural fires and provided a post-fire urine. Compared with baseline measurements, the mean fold change of post-fire urinary PAH-OHs increased similarly across roles, including captains (2.05 (95% CI 1.59-2.65)), engineers (2.10 (95% CI 1.47-3.05)), firefighters (2.83 (95% CI 2.14-3.71)), and paramedics (1.84 (95% CI 1.33-2.60)). Interior responses, smoke odor on skin, and lack of recent laundering or changing of hoods were significantly associated with increased post-fire urinary PAH-OHs.

SIGNIFICANCE

Ambient smoke from the fire represents an exposure hazard for all individuals on the fireground; engineers and paramedics in particular may not be aware of the extent of their exposure. Post-fire surveys identified specific risks associated with increased exposure.

Chrysene, a four-ring polycyclic aromatic hydrocarbon, induces hepatotoxicity in mice by activation of the aryl hydrocarbon receptor (AhR)

Polycyclic aromatic hydrocarbons (PAHs) are a group of persistent organic global environmental pollutants and cause harmful effects on human health. Here, we evaluated adverse effects of chrysene, which is a four-ring PAH and an important member of 16 priority PAHs, on the liver. Chrysene was detected in some common raw and cooked Chinese food samples. Hepatotoxicity including increased relative liver weight, hepatocyte swelling and degeneration, and elevated serum alanine aminotransferase (ALT) levels were observed in chrysene-exposed C57BL/6 mice. Glutamine treatment effectively ameliorated chrysene-induced mice liver injury by decreasing serum ALT levels. Chrysene induced mice hepatic glutathione depletion and oxidative DNA damage with increased 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels. Hepatic expression levels of the aryl hydrocarbon receptor (AhR), AhR-related target genes including CYP1A1, CYP1A2 and CYP1B1, and AhR nuclear translocator (ARNT) were significantly increased in chrysene-exposed C57BL/6 mice. Chrysene induced mice hepatic mRNA levels of the nuclear factor erythroid 2-related factor 2 (Nrf2) and Nrf2-mediated phase II detoxifying and antioxidant enzymes including NQO1, UGT1A1, UGT1A6, SULT1A1, GSTm1, GSTm3, Catalase (CAT), GPx1, and SOD2. We found that chrysene had toxic effects including increased relative liver weight and elevated serum ALT levels on AhR^+/+ mice but not AhR^-/- mice. Chrysene significantly induced hepatic mRNA levels of CYP1A1 and CYP1A2 in AhR^+/+ mice but not AhR^-/- mice. To our knowledge, this study is the first to demonstrate that hepatotoxicity causes by chrysene is dependent on AhR, and Nrf2 plays an important regulation role in protection against oxidative liver injury induced by chrysene.

GC-MS determination of the content of polycyclic aromatic hydrocarbons in bread and potato Tahdig prepared with the common edible oil

The polycyclic aromatic hydrocarbon (PAH) content of the Tahdig of the breads and potatoes prepared with edible oil was determined by GC-MS. The Tahdigs of bread and potato were baked under the same condition (volume of any oil 40 cc, temperature 180 °C, time 30 min). Polycyclic aromatic hydrocarbon determination was performed by an Agilent 6890 N Gas chromatography with mass selective detector, equipped with a capillary column. The highest contents of PAHs in Tahdig of bread and Tahdig of potato were observed in canola with 550 ± 3.9 ng/kg and sesame with 408.3 ± 41 ng/kg. The mean of PAH content was significantly higher in the Tahdig of bread compared to the Tahdig of potato (p < 0.05). Among the 16 PAHs examined by GC/MS, 10 PAHs were detected. The amount of high molecular weight (HMW) PAHs were significantly more than low molecular weight (LMW) PAHs (p < 0.05). Benzo [b]fluoranthene and benz[a]anthracene concentrations were significantly more than the other detected compounds (p < 0.05). Due to high PAH contamination of both Tahdig groups, the consumption of Tahdig (any type) was not recommended.

Biodegradation and Removal of PAHs by Bacillus velezensis Isolated from Fermented Food

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the environment. They are highly toxigenic and carcinogenic. Probiotic bacteria isolated from fermented foods were tested to check their ability to degrade and/or detoxify PAHs. Five probiotic bacteria with distinct morphologies were isolated from a mixture of 26 fermented foods co-cultured with benzo(a)pyrene (BaP) containing Bushnell Haas minimal broth. Among them, B. velezensis (PMC10) significantly reduced the abundance of BaP in the broth. PMC10 completely degraded BaP presented at a lower concentration in broth culture. B. velezensis also showed a clear zone of degradation on a BaP-coated Bushnell Haas agar plate. Gene expression profiling showed significant increases of PAH ringhydroxylating dioxygenases and 4-hydroxybenzoate 3-monooxygenase genes in B. velezensis in response to BaP treatment. In addtion, both live and heat-killed B. velezensis removed BaP and naphthalene (Nap) from phosphate buffer solution. Live B. velezensis did not show any cytotoxicity to macrophage or human dermal fibroblast cells. Live-cell and cell-free supernatant of B. velezensis showed potential anti-inflammatory effects. Cell-free supernatant and extract of B. velezensis also showed free radical scavenging effects. These results highlight the prospective ability of B. velezensis to biodegrade and remove toxic PAHs from the human body and suggest that the biodegradation of BaP might be regulated by ring-hydroxylating dioxygenase-initiated metabolic pathway.

Association between Polycyclic Aromatic Hydrocarbon Exposure and Diarrhea in Adults

Objective: Polycyclic aromatic hydrocarbons (PAHs) are not only natural but also anthropogenic contaminants that exist in many places in the environment. Human beings often accidentally ingest PAHs via smoking. Furthermore, smoking may increase the risk of bowel disorder, including diarrhea and other gastrointestinal problems. Therefore, PAH exposure is hypothesized to be related to diarrhea risk. This study discusses the association between diarrhea and PAH exposure in the United States adult population. Method: 10,537 participants from the National Health and Nutrition Examination Survey (NHANES 2001–2006) were involved in this cross-sectional analysis. Bowel disorders were assessed via examination of stool frequency and stool type. The concentrations of urinary PAH metabolites were used to evaluate PAH exposure. The association between bowel habits and PAH exposure was assessed using a multivariate logistic regression model with covariate assessment of gender, age, race, liver function, kidney function, and common chronic health diseases. Results: All PAH metabolites except 1-hydroxynaphthalene, 1-hydroxypyrene, and 9-hydroxyfluorene were substantially correlated with an increased risk of diarrhea (p < 0.05) after modification of relevant covariables. This study also revealed significant association in the group of females (p < 0.05). Furthermore, all PAH metabolites except 1-hydroxynaphthalene, 2-hydroxyphenanthrene, 1-hydroxypyrene, and 9-hydroxyfluorene show significantly positive association in the non-obesity group (BMI < 30, p < 0.05). Conclusions: PAH exposure is highly associated with risk of bowel disorders among the adult population in the United States, especially in female and non-obesity populations. More research is necessary to shed light on the pathophysiological mechanisms associated to PAH exposure and diarrhea.

Effect of Cigarette Smoke on Gut Microbiota: State of Knowledge

Cigarette smoke is a representative source of toxic chemical exposures to humans, and the adverse consequences of cigarette smoking are mediated by its effect on both neuronal and immune-inflammatory systems. Cigarette smoking also is a major risk factor for intestinal disorders, such as Crohn's disease and peptic ulcer. On the other hand, cigarette smoking is protective against developing ulcerative colitis. The effects of cigarette smoking on intestinal disorders include changes in intestinal irrigation and microbiome, increases in permeability of the mucosa, and impaired mucosal immune responses. However, the underlying mechanism linking cigarette smoking with intestinal microbiota dysbiosis is largely unknown. In this communication, we first review the current knowledge about the mechanistic interaction between cigarette smoke and intestinal microbiota dysbiosis, which include the likely actions of nicotine, aldehydes, polycyclic aromatic hydrocarbons, heavy metals, volatile organic compounds and toxic gases, and then reveal the potential mechanisms of the lung-gut cross talk and skin-gut cross talk in regulating the balance of intestinal microbiota and the interrelation of intestinal microbiota dysbiosis and systemic disorders.

A review of human and animals exposure to polycyclic aromatic hydrocarbons: Health risk and adverse effects, photo-induced toxicity and regulating effect of microplastics

Polycyclic aromatic hydrocarbons (PAHs) are one of the most widely distributed persistent organic pollutants (POPs) in the environmental media. PAHs have been widely concerned due to their significant health risk and adverse effects to human and animals. Currently, the main sources of PAHs in the environment are the incomplete combustion of fossil fuels, as well as municipal waste incineration and agricultural non-surface source emissions. In this work, the scope of our attention includes 16 typical PAHs themselves without involving their metabolites and industrial by-products. Exposure of human and animals to PAHs can lead to a variety of adverse effects, including carcinogenicity and teratogenicity, genotoxicity, reproductive- and endocrine-disrupting effects, immunotoxicity and neurotoxicity, the type and severity of which depend on a variety of factors. On the other hand, the regulatory effect of microplastics (MPs) on the bio-toxicity and bioaccumulation capacity of PAHs has now gradually attracted attention. We critically reviewed the adsorption capacity and mechanisms of MPs on PAHs as well as the effects of MPs on PAHs toxicity, thus highlighting the importance of paying attention to the joint bio-toxicity caused by PAHs-MPs interactions. In addition, due to the extensive nature of the common exposure pathway of PAHs and ultraviolet ray, an accurate understanding of biological processes exposed to both PAHs and UV light is necessary to develop effective protective strategies. Finally, based on the above critical review, we highlighted the research gaps and pointed out the priority of further studies.

Polycyclic Aromatic Hydrocarbon Levels in Wistar Rats Exposed to Ambient Air of Port Harcourt, Nigeria: An Indicator for Tissue Toxicity

This study investigated the PAH levels in Wistar rats exposed to ambient air of the Port Harcourt metropolis. Twenty Wistar rats imported from a nonpolluted city (Enugu) were exposed to both indoor and outdoor air. Following the IACUC regulation, baseline data were obtained from 4 randomly selected rats, while the remaining 16 rats (8 each for indoor and outdoor) were left till day 90. Blood samples were obtained by cardiac puncture, and the PAH levels were determined using Gas Chromatography Flame-Ionization Detector (GC-FID). GraphPad Prism (version 8.0.2) Sidak's (for multiple data set) and unpaired t-tests (for two data sets) were used to evaluate the differences in group means. Seven of the PAHs found in indoor and outdoor rats were absent in baseline rats. The mean concentrations of PAH in indoor and outdoor animals were higher than those of baseline animals, except for Benzo(a)pyrene, which was found in baseline animals but absent in other animal groups. Additionally, Dibenz(a,h)anthracene, Indeno(1,2,3-c,d)pyrene, Pyrene, 2-methyl, and other carcinogenic PAHs were all significantly higher (p < 0.05) in outdoor groups. The vulnerable groups in Port Harcourt are at the greatest risk of such pollution. Therefore, urgent environmental and public health measures are necessary to mitigate the looming danger.

State-of-the-Art of Strategies to Reduce Exhaust Emissions from Diesel Engine Vehicles

Compression ignition engines play a significant role in the development of a country. They are widely used due to their innate properties such as high efficiency, high power output, and durability. However, they are considered one of the key contributors to transport-related emission and have recently been identified as carcinogenic. Thus, it is important to modify the designs and processes before, during, and after combustion to reduce the emissions to meet the strict emission regulations. The paper discusses the pros and cons of different strategies to reduce emissions of a diesel engine. An overview of various techniques to modify the pre-combustion engine design aspects has been discussed first. After that, fuel modifications techniques during combustion to improve the fuel properties to reduce the engine-out emission is discussed. Finally, post-combustion after-treatment devices are briefly discussed, which help improve the air quality of our environment.

Microbial Degradation of Naphthalene and Substituted Naphthalenes: Metabolic Diversity and Genomic Insight for Bioremediation

Low molecular weight polycyclic aromatic hydrocarbons (PAHs) like naphthalene and substituted naphthalenes (methylnaphthalene, naphthoic acids, 1-naphthyl N-methylcarbamate, etc.) are used in various industries and exhibit genotoxic, mutagenic, and/or carcinogenic effects on living organisms. These synthetic organic compounds (SOCs) or xenobiotics are considered as priority pollutants that pose a critical environmental and public health concern worldwide. The extent of anthropogenic activities like emissions from coal gasification, petroleum refining, motor vehicle exhaust, and agricultural applications determine the concentration, fate, and transport of these ubiquitous and recalcitrant compounds. Besides physicochemical methods for cleanup/removal, a green and eco-friendly technology like bioremediation, using microbes with the ability to degrade SOCs completely or convert to non-toxic by-products, has been a safe, cost-effective, and promising alternative. Various bacterial species from soil flora belonging to Proteobacteria (Pseudomonas, Pseudoxanthomonas, Comamonas, Burkholderia, and Novosphingobium), Firmicutes (Bacillus and Paenibacillus), and Actinobacteria (Rhodococcus and Arthrobacter) displayed the ability to degrade various SOCs. Metabolic studies, genomic and metagenomics analyses have aided our understanding of the catabolic complexity and diversity present in these simple life forms which can be further applied for efficient biodegradation. The prolonged persistence of PAHs has led to the evolution of new degradative phenotypes through horizontal gene transfer using genetic elements like plasmids, transposons, phages, genomic islands, and integrative conjugative elements. Systems biology and genetic engineering of either specific isolates or mock community (consortia) might achieve complete, rapid, and efficient bioremediation of these PAHs through synergistic actions. In this review, we highlight various metabolic routes and diversity, genetic makeup and diversity, and cellular responses/adaptations by naphthalene and substituted naphthalene-degrading bacteria. This will provide insights into the ecological aspects of field application and strain optimization for efficient bioremediation.

Chemopreventive effect of galangin against benzo(a)pyrene-induced stomach tumorigenesis through modulating aryl hydrocarbon receptor in Swiss albino mice

The present study was aimed to evaluate the chemopreventive potential of galangin against benzo(a)pyrene (BaP)-induced stomach carcinogenesis in Swiss albino mice. Stomach cancer was induced in experimental mice using BaP oral administration. The mice were treated with galangin (10 mg/kg b.wt.) before and during BaP administration. Oral administration of galangin at a dose of 10 mg/kg b.wt. significantly (p < 0.05) prevented the tumor incidence, tumor volume in the experimental animals. Further, galangin pretreatment prevents BaP-induced lipid peroxidation and restores BaP-mediated loss of cellular antioxidants status. It has also been found that galangin prevents BaP-induced activation of phase I detoxification enzymes. Furthermore, galangin pretreatment prevented the BaP-induced overexpression of cytochrome P450s isoform genes (CYP1A1, CYP1B1), aryl hydrocarbon receptor system (AhR, ARNT), transcriptional activators (CBP/p300, NF-kB), tumor growth factors, proto-oncogenes, invasion markers (TGFB, SRC-1, MYC, iNOS, MMP2, MMP9) and Phase II metabolic isoenzyme genes (GST) in the stomach tissue homogenate when compared to the control groups. The western blot results confirm that galangin (10 mg/kg. b.wt.) treatment significantly prevented the BaP-mediated expression of ArR, ARNT, and CYP1A1 proteins in the mouse stomach tissue. Therefore, the present results confirm that galangin prevents BaP-induced stomach carcinogenesis probably through modulating ArR and ARNT expression in the experimental mice.

Physiologically-based pharmacokinetic modeling of benzo(a)pyrene and the metabolite in humans of different ages

Age-specific differences in the pharmacokinetics of benzo(a)pyrene (BaP) and its metabolite 3-hydroxybenzo(a)pyrene (3-OHBaP) potentially affect time courses of tissue concentration; however, the quantitative impact of these differences is not well characterized. Our objective was to quantify the effect of age-specific differences in physiological and biochemical parameters on the pharmacokinetics of BaP and 3-OHBaP from newborn at birth to adulthood following inhalation exposure. The time courses of BaP and 3-OHBaP were simulated by using a physiologically based pharmacokinetic model with Advanced Continuous Simulation Language (ACSLX). The concentrations of BaP increased with age in the liver but decreased with age in most tissues, urine, and blood. The concentrations of 3-OHBaP were the highest in the newborns. Our results also showed that the concentration of BaP has almost reached a steady state in the kidney, liver, lung, rapidly perfused tissues, slowly perfused tissues, and skin except for adipose tissues. However, the concentration of 3-OHBaP has reached a steady state in all tissues. This study suggests that age-specific parameters have an effect on the pharmacokinetics of BaP and 3-OHBaP. In particular, tissue concentration in the newborns is higher than other age groups, which indicates that the newborns are susceptible to environmental BaP exposure.

Risk of two common glandular cell-type cancers (breast and colorectal cancers) in Chinese occupational chefs: a nationwide ecological study in Taiwan

OBJECTIVES

Cooking oil fumes (COFs) contain many carcinogens. We investigated the association between COFs and incidence risk of colorectal cancer and female breast in chefs.

METHODS

We identified Chinese food chefs and non-Chinese food chefs from Taiwan's national database of certified chefs in 1984-2007. In total, 379,275 overall and 259,450 females had not been diagnosed as having any cancer before chef certification. We followed these chefs in Taiwan's Cancer Registry Database (1979-2010) and Taiwan's National Death Statistics Database (1985-2011) for newly diagnosed colorectal cancer and female breast cancer.

RESULTS

A total of 4,218,135 and 2,873,515 person-years were included in our analysis of colorectal cancer and female breast cancer incidence, respectively. Compared to non-Chinese food chefs, the Chinese food chefs had an adjusted IRR for colorectal cancer of 1.65 (95% CI  1.17-2.33). The risk of colorectal cancer was even higher among female Chinese food chefs certified for more than 5 years (adjusted incident rate ratio (IRR) = 2.39, 95% CI   1.38-4.12). For female breast cancer, the risk was also significant (adjusted IRR = 1.40, 95% CI 1.10-1.78) and the risks were even higher in female Chinese food chefs certified for more than 5 years (adjusted IRR = 1.74, 95% CI 1.37-2.22).

CONCLUSIONS

This study found that Chinese food chefs had an increased risk of colorectal cancer and female breast cancer, particularly female chefs who had worked for more than 5 years. Future human and animal studies are necessary to re-confirm these findings.

Dietary exposure and cancer risk assessment of the Pakistani population exposed to polycyclic aromatic hydrocarbons

The sixteen-priority polycyclic aromatic hydrocarbons (PAHs) were determined in twenty-one groceries from six food groups consumed by the Pakistani population. The highest concentration of the total PAHs was found in fish (243 ng g^-1), while the lowest concentration was determined in rice (53 ng g^-1). The total B[a]P_eq dietary exposure for the male group followed an increasing order of children (865.5 ng day^-1) < adolescents (2301 ng day^-1) < seniors (2864 ng day^-1) < adults (3004 ng day^-1), whereas the similar order was also observed for the female group. The male group showed 1-8.5% (mean 5.5%) of higher exposure amount compared to the female group. Among all food categories, wheat (43%) and milk (34%) contributed the greatest while rice (1%) and egg (1%) contributed the smallest to the total dietary exposure of PAHs. The incremental lifetime cancer risk (ILCR) values for the adults and children revealed a potential cancer risk to the both male and female groups. Whereas at the 95th percentiles, the ILCR values for all age and gender groups exceeded the limit (>10^-5), demonstrating a high potential cancer risk in the Pakistani population. The sensitivity analysis found that the daily dietary intake, exposure duration and the cancer slope factor were the most influential variables contributed to the total variance of risk.

A Review and Bibliometric Analysis on Applications of Microbial Degradation of Hydrocarbon Contaminants in Arctic Marine Environment at Metagenomic and Enzymatic Levels

The globe is presently reliant on natural resources, fossil fuels, and crude oil to support the world's energy requirements. Human exploration for oil resources is always associated with irreversible effects. Primary sources of hydrocarbon pollution are instigated through oil exploration, extraction, and transportation in the Arctic region. To address the state of pollution, it is necessary to understand the mechanisms and processes of the bioremediation of hydrocarbons. The application of various microbial communities originated from the Arctic can provide a better interpretation on the mechanisms of specific microbes in the biodegradation process. The composition of oil and consequences of hydrocarbon pollutants to the various marine environments are also discussed in this paper. An overview of emerging trends on literature or research publications published in the last decade was compiled via bibliometric analysis in relation to the topic of interest, which is the microbial community present in the Arctic and Antarctic marine environments. This review also presents the hydrocarbon-degrading microbial community present in the Arctic, biodegradation metabolic pathways (enzymatic level), and capacity of microbial degradation from the perspective of metagenomics. The limitations are stated and recommendations are proposed for future research prospects on biodegradation of oil contaminants by microbial community at the low temperature regions of the Arctic.

Parvimonas micra, Peptostreptococcus stomatis, Fusobacterium nucleatum and Akkermansia muciniphila as a four-bacteria biomarker panel of colorectal cancer

Dysbiosis of the gut microbiome has been associated with the pathogenesis of colorectal cancer (CRC). We profiled the microbiome of gut mucosal tissues from 18 CRC patients and 18 non-CRC controls of the UKM Medical Centre (UKMMC), Kuala Lumpur, Malaysia. The results were then validated using a species-specific quantitative PCR in 40 CRC and 20 non-CRC tissues samples from the UMBI-UKMMC Biobank. Parvimonas micra, Fusobacterium nucleatum, Peptostreptococcus stomatis and Akkermansia muciniphila were found to be over-represented in our CRC patients compared to non-CRC controls. These four bacteria markers distinguished CRC from controls (AUROC = 0.925) in our validation cohort. We identified bacteria species significantly associated (cut-off value of > 5 fold abundance) with various CRC demographics such as ethnicity, gender and CRC staging; however, due to small sample size of the discovery cohort, these results could not be further verified in our validation cohort. In summary, Parvimonas micra, Fusobacterium nucleatum, Peptostreptococcus stomatis and Akkermansia muciniphila were enriched in our local CRC patients. Nevertheless, the roles of these bacteria in CRC initiation and progression remains to be investigated.

The Activation of Procarcinogens by CYP1A1/1B1 and Related Chemo-Preventive Agents: A Review

CYP1A1 and CYP1B1 are extrahepatic P450 family members involved in the metabolism of procarcinogens, such as PAHs, heterocyclic amines and halogen-containing organic compounds. CYP1A1/1B1 also participate in the metabolism of endogenous 17-β-estradiol, producing estradiol hydroquinones, which are the intermediates of carcinogenic semiquinones and quinones. CYP1A1 and CYP1B1 proteins share approximately half amino acid sequence identity but differ in crystal structures. As a result, CYP1A1 and CYP1B1 have different substrate specificity to chemical procarcinogens. This review will introduce the general molecular biology knowledge of CYP1A1/1B1 and the metabolic processes of procarcinogens regulated by these two enzymes. Over the last four decades, a variety of natural products and synthetic compounds which interact with CYP1A1/1B1 have been identified as effective chemo-preventive agents against chemical carcinogenesis. These compounds are mainly classified as indirect or direct CYP1A1/1B1 inhibitors based on their distinct mechanisms. Indirect CYP1A1/1B1 inhibitors generally impede the transcription and translation of CYP1A1/1B1 genes or interfere with the translocation of aryl hydrocarbon receptor (AHR) from the cytosolic domain to the nucleus. On the other hand, direct inhibitors inhibit the catalytic activities of CYP1A1/1B1. Based on the structural features, the indirect inhibitors can be categorized into the following groups: flavonoids, alkaloids and synthetic aromatics, whereas the direct inhibitors can be categorized into flavonoids, coumarins, stilbenes, sulfur containing isothiocyanates and synthetic aromatics. This review will summarize the in vitro and in vivo activities of these chemo-preventive agents, their working mechanisms, and related SARs. This will provide a better understanding of the molecular mechanism of CYP1 mediated carcinogenesis and will also give great implications for the discovery of novel chemo-preventive agents in the near future.

Estimations of benchmark dose for urinary metabolites of coke oven emissions among workers

Coke oven emissions (COEs), usually composed of polycyclic aromatic hydrocarbons (PAHs) and so on, may alter the relative telomere length of exposed workers and have been linked with adverse health events. However, the relevant biological exposure limits of COEs exposure has not been evaluated from telomere damage. The purpose of this study is to estimate benchmark dose (BMD) of urinary PAHs metabolites from COEs exposure based on telomere damage with RTL as a biomarker. A total of 544 exposed workers and 238 controls were recruited for participation. High-performance liquid chromatography and qPCR were used to detect concentrations of urinary mono-hydroxylated PAHs and relative telomere length in peripheral blood leukocytes for all subjects. The benchmark dose approach was used to estimate benchmark dose (BMD) and its lower 95% confidence limit (BMDL) of urinary OH-PAHs of COEs exposure based on telomere damage. Our results showed that telomere length in the exposure group (0.75 (0.51, 1.08)) was shorter than that in the control group (1.05 (0.76,1.44))(P < 0.05), and a dose-response relationship was shown between telomere damage and both 1-hydroxypyrene and 3-hydroxyphenanthrene in urine. The BMDL of urinary 1-hydroxypyrene from the optimal model for telomere damage was 1.96, 0.40, and 1.01 (μmol/mol creatinine) for the total, males, and females group, respectively. For 3-hydroxyphenanthrene, the BMDL was 0.94, 0.33, and 0.49 (μmol/mol creatinine) for the total, males, and females. These results contribute to our understanding of telomere damage induced by COEs exposure and provide a reference for setting potential biological exposure limits.

Lymphocyte micronuclei frequencies in skin, haematological, prostate, colorectal and esophageal cancer cases: A systematic review and meta-analysis

Micronucleus (MN) assay has been widely used as a biomarker of DNA damage, chromosomal instability, cancer risk and accelerated aging in many epidemiological studies. In this narrative review and meta-analysis we assessed the association between lymphocyte micronuclei (MNi) and cancers of the skin, blood, digestive tract, and prostate. The review identified nineteen studies with 717 disease subjects and 782 controls. Significant increases in MRi for MNi were observed in the following groups: subjects with blood cancer (MRi = 3.98; 95 % CI: 1.98-7.99; p = 0.000) and colorectal cancer (excluding IBD) (MRi = 2.69; 95 % CI: 1.82-3.98, p < 0.000). The results of this review suggest that lymphocyte MNi are a biomarker of DNA damage and chromosomal instability in people with haematological or colorectal cancers. However, the MRi for lymphocyte MNi in subjects with cancers of skin, prostate, esophagus was not significantly increased. More case-control and prospective studies are warranted to further verify the observed trends and to better understand the role of lymphocyte MNi as a biomarker of cancer risk in blood, skin, digestive tract and prostate.

Polycyclic aromatic hydrocarbon metabolites and mortality risk in an adult population

Occupational polycyclic aromatic hydrocarbons (PAHs) exposure has been shown to increase the risk of various cancers and may be associated with carcinogenic mortality. However, no study has explored the relationship between environmental PAH exposure and mortality in general population. The aim of our study was to explore the association between PAH exposure and all-cause, cardiovascular, and cancer mortality in a general US adult population. We analyzed data from the National Health and Nutrition Examination Survey (NHANES 2001-2006) based on the information in this dataset on 692 males and 717 females. PAH exposure was detected using biomarkers from urine samples. Follow-up data on mortality were derived from initial examination of the subjects until death or 31 December 2006 in the NHANES database. We calculated hazard ratios (HRs) of PAH metabolites among all-cause, cardiovascular, and cancer mortality using the multivariate Cox proportional hazards regression model after adjusting for covariates. Among males, 3-phenanthrene was positively associated with increased risk of all-cause mortality (HR 1.043, 95%CI 1.019-1.066). Female participants with higher 2-napthol (HR 1.043, 95%CI 1.014-1.072), 3-fluorene (HR 2.159, 95%CI 1.233-3.779), and 1-phenanthrene (HR = 1.259, 95%CI 1.070-1.481) levels had increased all-cause mortality. In addition, high 3-phenanthrene (HR 1.333, 95%CI 1.008-1.763) and 1-phenanthrene (HR 1.463, 95%CI 1.126-1.900) levels increased the risk of cardiovascular mortality. However, there were no significant findings for cancer mortality in both genders. Environmental PAH exposure among the adult population is associated with non-carcinogenic but not cancer mortality. Future studies are warranted to determine the underlying mechanisms related to these findings.

Suspended fine particulate matter (PM2.5), microplastics (MPs), and polycyclic aromatic hydrocarbons (PAHs) in air: Their possible relationships and health implications

Exposure to fine particulate matter (PM_2.5) and their associated microcontaminants have been linked to increased harmful effects on the human health. In this study, the possible relationships between PM_2.5, microplastics (MPs), and polycyclic aromatic hydrocarbons (PAHs) were analyzed in an urban area of Bushehr port, in the northern part of the Persian Gulf. Presence, sources, and health risks of MPs and PAHs in both normal and dusty days were also investigated. The median of PM_2.5 and ƩPAHs were 52.8 μg/m³ and 14.1 ng/m³, respectively, indicating high pollution levels especially in dusty days. The mean level of MPs in urban suspended PM_2.5 was 5.2 items/m³. Fragments were the most abundant shape of identified MPs and polyethylene terephthalate (PET) was the most plastic types in urban dust of Bushehr port. The results revealed that PM_2.5 and MPs may possibly act as a carrier for airborne MPs and PAHs, respectively. In addition, the significant positive relationships between MPs, wind speed and wind direction, confirmed that the MPs transportation were highly controlled by atmospheric condition. Moreover, the source identification methods and trajectory analyses indicated that petrogenic sources from both proximal and distal origins play an important role in the level of PAHs. The results of chronic health risk evaluation via inhalation revealed that PM_2.5-bound PAHs had high potential cancer risk in winter, while, the estimated risks for non-carcinogenic PAHs were not considerable. In the case of MPs, the assessment of human intake of MPs via inhalation highlighted the possible risks for habitants.

Evaluation of public knowledge and beliefs of adverse health effects of unhealthy food and knowledge and beliefs based inequalities among various socio-demographic groups in Lithuania

OBJECTIVES

The availability of information on healthy products does not ensure the empowerment of people with the knowledge on how to choose or avoid food products or dishes depending on unhealthy factors. Public knowledge and beliefs of unhealthy food effects on health needs to be evaluated so that appropriate measures can be taken to properly inform people and relevant socio-demographic groups.

METHODS

The original survey questionnaire containing questions about specific food groups and various health effects was compiled. A total of 1,007 respondents, Lithuanian residents aged 18-75 years, were surveyed in March 2019. Multilevel stratified probability sampling method was used for data representativeness.

RESULTS

Almost half of respondents (46.2%) knew that deep-fried food could cause cancer. The majority of respondents (68.4%) were aware that sugar causes obesity and 61.7% were aware that sugar increases the risk of diabetes mellitus; 41.6% (more often those living in non-rural areas) know that grilled meat may cause cancer. More than half of respondents (57.2%) (more likely those living in non-rural areas and those with a university degree) were aware that smoked meat products may cause cancer. Only 46.4% were aware of the fact that salt raises blood pressure and the risk of cardiovascular diseases.

CONCLUSION

Only about half of Lithuanian residents aged 18-75 were aware of the scientifically proven harmful effects of unhealthy food groups. Socio-demographic factors influence the knowledge and beliefs of the population.

Risk Assessment for People Exposed to PM2.5 and Constituents at Different Vertical Heights in an Urban Area of Taiwan

Environmental epidemiological studies have consistently reported associations between ambient particulate matter (PM) concentrations and everyday mortality/morbidity. Many urban dwellers in Asia live in high-rise apartment buildings; thus, the pollutant concentrations of their immediate outdoor environments are affected by the vertical distribution of pollutants in the atmosphere. The vertical distributions of pollutants provide unique information about their sources and dynamic transport in urban areas, as well as their relationship to people’s exposure at ground level, while the vertical distributions of pollutants have rarely been considered in exposure assessment. In the current study, PM concentrations (with aerodynamic diameters less than 1.0 μm (PM1), 2.5 μm (PM2.5), and 10 μm (PM10)), nanoparticles, black carbon (BC), and particle-bound polycyclic aromatic hydrocarbons (p-PAHs) were measured at different residential heights—6 m, 16 m, and 27 m—at Feng Chia University near a popular night market in Western Taiwan. PM2.5 data were further adopted for health risk estimations. In winter, the magnitude of PM1, PM2.5, and PM10 concentrations were 16 m > 6 m > 27 m; nanoparticle concentrations were 6 m > 27 m > 16 m; and BC and p-PAHs concentrations were 27 m > 16 m > 6 m. In summer, PM1, PM2.5, and PM10 concentrations ranged from 6 m > 16 m > 27 m; nanoparticle concentrations were 6 m > 16 m; and BC and p-PAHs concentrations were from 27 m > 16 m. PM and constituents concentrations during winter were significantly higher in the nighttime than those in daytime, and levels of PM1, PM2.5, and PM10 increased rapidly on 6 m and 16 m heights (but did not increase at 27 m) after 5 pm, whereas these trends became less significant in summer. Health risk analysis for PM2.5 concentrations showed a decrease in lung cancer mortality rate and an extended lifespan for residents living at 27 m. Overall, the current study investigated the vertical profile of particulate matters and analyzed health impacts of PM2.5 at different residential heights in urban area of Taiwan. As the distributions of PM and the constituents varied at different residential heights, exposure and risk assessment of particle concentrations with multiple sizes and various components at broader vertical heights should be further investigated.

Lycopene enriched tomato extract suppresses chemically induced skin tumorigenesis in mice

Abstract. The present study revealed the effects of Lycopene enriched tomato extract (LycT) on chemically induced skin cancer in mice. Skin tumors were induced by topical application of 7,12-Dimethylbenz(a)anthracene (DMBA) [500 nmol/100 ul of acetone, twice a week for two weeks] and 12-O-tetradecanoyl phorbol-13-acetate (TPA) [1.7 nmol/100 ul of acetone, twice a week for eighteen weeks] and LycT (5 mg/kg b.w.) was administered orally. Male Balb/c mice were divided into four groups (n = 15 per group): control, DMBA/TPA, LycT and LycT + DMBA/TPA. The chemopreventive response of LycT to skin tumorigenesis was evident by inhibition in tumor incidence, number, size, burden and volume in LycT + DMBA/TPA group when compared to DMBA/TPA group. This was associated with inhibition of cell proliferation in LycT + DMBA/TPA group as observed by the decrease in epidermal morphometric parameters and mRNA and protein expression of proliferating cell nuclear antigen when compared to DMBA/TPA group (p ≤ 0.05). LycT decreased (p ≤ 0.05) the mRNA and protein expression of angiogenic genes (vascular endothelial growth factor, angiopoietin-2, basic fibroblast growth factor) in LycT + DMBA/TPA group, suggesting its anti-angiogenic effects. The increase (p ≤ 0.05) in protein expression of connexin-32 and 43 in LycT + DMBA/TPA group suggests improved inter cellular communication when compared to DMBA/TPA group. Histochemical studies demonstrated that the components of extracellular matrix (fibrous proteins and mucopolysaccharides) were also modulated during skin carcinogenesis and its chemoprevention by LycT. The decrease in cell proliferation parameters and expression of angiogenesis associated genes, modulation of ECM components and increase in expression of connexins suggest that LycT improved multiple dysregulated processes during chemoprevention of skin cancer.

Microbiota and Cancer: The Emerging Beneficial Role of Bifidobacteria in Cancer Immunotherapy

Many intestinal bacteria are believed to be involved in various inflammatory and immune processes that influence tumor etiology because of their metabolic properties and their ability to alter the microbiota homeostasis. Although many functions of the microbiota are still unclear, there is compelling experimental evidence showing that the intestinal microbiota is able to modulate carcinogenesis and the response to anticancer therapies, both in the intestinal tract and other body sites. Among the wide variety of gut-colonizing microorganisms, various species belonging to the Bifidobacterium genus are believed to elicit beneficial effects on human physiology and on the host-immune system. Recent findings, based on preclinical mouse models and on human clinical trials, have demonstrated the impact of gut commensals including bifidobacteria on the efficacy of tumor-targeting immunotherapy. Although the underlying molecular mechanisms remain obscure, bifidobacteria and other microorganisms have become a promising aid to immunotherapeutic procedures that are currently applied to treat cancer. The present review focuses on strategies to recruit the microbiome in order to enhance anticancer responses and develop therapies aimed at fighting the onset and progression of malignancies.

Review article: impact of cigarette smoking on intestinal inflammation-direct and indirect mechanisms

BACKGROUND

The inflammatory bowel diseases, Crohn's disease and ulcerative colitis are related multifactorial diseases. Their pathogenesis is influenced by each individual's immune system, the environmental factors within exposome and genetic predisposition. Smoking habit is the single best-established environmental factor that influences disease phenotype, behaviour and response to therapy.

AIM

To assess current epidemiological, experimental and clinical evidence that may explain how smoking impacts on the pathogenesis of inflammatory bowel disease.

METHODS

A Medline search for 'cigarette smoking', in combination with terms including 'passive', 'second-hand', 'intestinal inflammation', 'Crohn's disease', 'ulcerative colitis', 'colitis'; 'intestinal epithelium', 'immune system', 'intestinal microbiota', 'tight junctions', 'mucus', 'goblet cells', 'Paneth cells', 'autophagy'; 'epigenetics', 'genes', 'DNA methylation', 'histones', 'short noncoding/long noncoding RNAs'; 'carbon monoxide/CO' and 'nitric oxide/NO' was performed.

RESULTS

Studies found evidence of direct and indirect effects of smoking on various parameters, including oxidative damage, impairment of intestinal barrier and immune cell function, epigenetic and microbiota composition changes, that contribute to the pathogenesis of inflammatory bowel disease.

CONCLUSIONS

Cigarette smoking promotes intestinal inflammation by affecting the function and interactions among intestinal epithelium, immune system and microbiota/microbiome.

Household Fuel Use and the Risk of Gastrointestinal Cancers: The Golestan Cohort Study

BACKGROUND

Three billion people burn nonclean fuels for household purposes. Limited evidence suggests a link between household fuel use and gastrointestinal (GI) cancers.

OBJECTIVES

We investigated the relationship between indoor burning of biomass, kerosene, and natural gas with the subsequent risk of GI cancers.

METHODS

During the period 2004-2008, a total of 50,045 Iranian individuals 40-75 years of age were recruited to this prospective population-based cohort. Upon enrollment, validated data were collected on demographics, lifestyle, and exposures, including detailed data on lifetime household use of different fuels and stoves. The participants were followed through August 2018 with < 1 % loss.

RESULTS

During the follow-up, 962 participants developed GI cancers. In comparison with using predominantly gas in the recent 20-y period, using predominantly biomass was associated with higher risks of esophageal [hazard ratio (HR): 1.89; 95% confidence interval (CI): 1.02, 3.50], and gastric HR: 1.83; 95% CI: 1.01, 3.31) cancers, whereas using predominantly kerosene was associated with higher risk of esophageal cancer (HR: 1.84; 95% CI: 1.10, 3.10). Lifetime duration of biomass burning for both cooking and house heating (exclusive biomass usage) using heating-stoves without chimney was associated with higher risk of GI cancers combined (10-y HR: 1.14; 95% CI: 1.07, 1.21), esophageal (10-y HR: 1.19; 95% CI: 1.08, 1.30), gastric (10-y HR: 1.11; 95% CI: 1.00, 1.23), and colon (10-y HR: 1.26; 95% CI: 1.03, 1.54) cancers. The risks of GI cancers combined, esophageal cancer, and gastric cancer were lower when biomass was burned using chimney-equipped heating-stoves (strata difference p -values = 0.001 , 0.003, and 0.094, respectively). Duration of exclusive kerosene burning using heating-stoves without chimney was associated with higher risk of GI cancers combined (10-y HR: 1.05; 95% CI: 1.00, 1.11), and esophageal cancer (10-y HR: 1.14; 95% CI: 1.04, 1.26).

DISCUSSION

Household burning of biomass or kerosene, especially without a chimney, was associated with higher risk of some digestive cancers. Using chimney-equipped stoves and replacing these fuels with natural gas may be useful interventions to reduce the burden of GI cancers worldwide. https://doi.org/10.1289/EHP5907.

Quantitative Analysis of Heavy Metals and Organic Compounds in Soil from Deir Kanoun Ras El Ain Dump, Lebanon

Recently, there has been a worldwide concern regarding soil contamination by heavy metals and organic compounds, especially in the developing countries including Lebanon that has suffered from solid waste mismanagement for decades. Deir Kanoun Ras El Ain is a village in southern Lebanon that possesses one of the country's worst dumps, and its leachates influx into a running canal that irrigates surrounding agricultural lands. The aim of this study was to determine the levels of some toxic heavy metals and organic compounds in different soil samples collected from the dump and along the canal during winter and summer seasons. Six research sites (four from the dump and two along the canal) were selected, and the soil samples for analysis were collected from a depth of around 10 cm. Heavy metals (lead, cadmium, arsenic, and mercury) and organic compounds (phthalates, bisphenol A, and polyaromatic hydrocarbons) content were determined using atomic absorption and high pressure liquid chromatography, respectively. The conducted research confirmed high levels of contamination in the collected soil samples by both heavy metals and organic compounds. The present study provided evidence that different sampling sites accumulated heavy metals at concentrations that exceeded the average maximum permissible levels for sewage sludge and agricultural land. These findings suggest the need for mitigation measures by the Lebanese authorities and new waste management programs to resolve the problems associated with uncontrolled dumping of solid wastes in Lebanon.

Increased mitochondrial content and function by resveratrol and select flavonoids protects against benzo[a]pyrene-induced bioenergetic dysfunction and ROS generation in a cell model of neoplastic transformation

Dietary polyphenols act in cancer prevention and may inhibit carcinogenesis. A possible mitochondrial mechanism for carcinogen-induced neoplastic transformation and chemoprevention by polyphenols, however, is largely unexplored. Using the Bhas 42 cell model of carcinogen-induced neoplastic transformation, we investigated benzo[a]pyrene (B[a]P) along with different polyphenols for their effects on mitochondrial content and function, and on mitochondrial and intracellular ROS generation. Bhas 42 cells were either co-treated with 5 μM polyphenol starting 2 h before exposure to 4 μM B[a]P for 24 or 72 h, or pre-treated with polyphenol for 24 h and removed prior to B[a]P exposure. Exposure to B[a]P decreased mitochondrial content (by 46% after 24 h and 30% after 72 h), decreased mitochondrial membrane potential and cellular ATP, and increased generation of mitochondrial superoxide and intracellular ROS. Polyphenol co-treatments protected against the decreased mitochondrial content, with resveratrol being the most effective (increasing the mitochondrial content after 72 h by 75%). Measurements after 24 h of mRNA for mitochondria-related proteins and of SIRT1 enzyme activity suggested an involvement of increased mitochondrial biogenesis in the polyphenol effects. The polyphenol co-treatments also ameliorated B[a]P-induced deficits in mitochondrial function (most strongly resveratrol), and increases in generation of mitochondrial superoxide and intracellular ROS. Notably, 24 h pre-treatments with polyphenols strongly suppressed subsequent B[a]P-induced increases, after 24 and 72 h, in mitochondrial superoxide and intracellular ROS generation, with resveratrol being the most effective. In conclusion, the results support a mechanism for B[a]P carcinogenesis involving impaired mitochondrial function and increased mitochondria-derived ROS, that can be ameliorated by dietary polyphenols. The evidence supports an increase in mitochondrial biogenesis behind the strong chemoprevention by resveratrol, and a mitochondrial antioxidant effect in chemoprevention by quercetin.

Future Trends for In Situ Monitoring of Polycyclic Aromatic Hydrocarbons in Water Sources: The Role of Immunosensing Techniques

Polycyclic aromatic hydrocarbons (PAHs) are hazardous environmental pollutants found in water, soil, and air. Exposure to this family of chemicals presents a danger to human health, and as a result, it is imperative to design methods that are able to detect PAHs in the environment, thus improving the quality of drinking water and agricultural soils. This review presents emerging immunoassay techniques used for in situ detection of PAH in water samples and how they compare to common-place techniques. It will discuss their advantages and disadvantages and why it is required to find new solutions to analyze water samples. These techniques are effective in reducing detection times and complexity of measurements. Immunoassay methods presented here are able to provide in situ analysis of PAH concentrations in a water sample, which can be a great complement to existing laboratory techniques due to their real-time screening and portability for immunoassay techniques. The discussion shows in detail the most relevant state-of-the-art surface functionalization techniques used in the field of immunosensors, with the aim to improve PAH detection capabilities. Specifically, three surface functionalization techniques are key approaches to improve the detection of PAHs, namely, substrate surface reaction, layer-by-layer technique, and redox-active probes. These techniques have shown promising improvements in the detection of PAHs in water samples, since they show a wider linear range and high level of sensitivity compared to traditional PAH detection techniques. This review explores the various methods used in the detection of PAH in water environments. It provides extra knowledge to scientists on the possible solutions that can be used to save time and resources. The combination of the solutions presented here shows great promise in the development of portable solutions that will be able to analyze a sample in a matter of minutes on the field.

Chemoprevention of Colorectal Cancer by Anthocyanidins and Mitigation of Metabolic Shifts Induced by Dysbiosis of the Gut Microbiome

Diets rich in fat, smoking, as well as exposure to environmental pollutants and dysbiosis of gut microbiota, increase the risk of developing colorectal cancer. Much progress has been made in combating colorectal cancer. However, options for chemoprevention from environmental insult and dysbiosis of gut microbiota remain elusive. We investigated the influence of berry-derived anthocyanidins (Anthos), with and without encapsulating them in bovine milk-derived exosomes (ExoAnthos), on the chemoprevention of bacteria-driven colon tumor development. Anthos and ExoAnthos treatment of colon cancer cells showed dose-dependent decreases in cell viability. Calculated selectivity index (SI) values for Anthos and ExoAnthos suggest that both treatments selectively targeted cancer over normal colon cells. In addition, ExoAnthos treatment yielded higher SI values than Anthos. Anthos and ExoAnthos treatment of Apc^Min/+ mice inoculated with enterotoxigenic Bacteriodes fragilis (ETBF) bacteria led to significant decreases in colon tumor numbers over mice receiving vehicle treatments. Western blot analysis of normal colon, colon tumor, and liver tissue lysates showed that mice inoculated with ETBF featured increased expression of phase I enzymes in normal colon tissue and decreased expression of phase II enzymes in liver tissue. Treatment with the Anthos and ExoAnthos reverted the modulation of phase I and phase II enzymes, respectively; no significant changes in phase II enzyme expression occurred in colon tumor tissue. Treatment of HCT-116 cells with the ubiquitous carcinogen, benzo[a]pyrene (B[a]P) led to similar modulation of phase I and II enzymes, which was partially mitigated by treatment with Anthos. These results provide a promising outlook on the impact of berry Anthos for prevention and treatment of bacteria- and B[a]P-driven colorectal cancer.

Accumulation and translocation of phenanthrene, anthracene and pyrene in winter wheat affected by soil water content

Polycyclic aromatic hydrocarbons (PAHs) are universal organic pollutants in the agro ecosystems in China, therefore, it is important to understand the uptake and accumulation of PAHs in crops growing on PAHs contaminated soils for human health risk assessments. Water management is a common practice to maintain high grain yields during wheat production. However, the effects of soil water content on the accumulation and translocation of PAHs in wheat are still not clear. The main objectives of the present study were to investigate the effects of soil water content on the accumulation of three selected PAHs (Σ₃PAHs, phenanthrene, anthracene and pyrene) in wheat during whole plant growth stage and on translocation or remobilization of Σ₃PAHs from vegetative tissues to wheat grains. Winter wheat (Triticum aestivum cv. Xiaoyan22) were grown on Σ₃PAHs spiked soils maintaining 80%, 60% or 40% water-holding capacity during the whole plant growth stage. Plant samplings were performed at jointing, anthesis or maturity stage, respectively. The present study showed that grain yield and biomass of the crop increased with soil water content increasing. Transpiration rate of wheat leaf under 80% and 60% water-holding capacity treatments was significantly (p < 0.05) higher than that under 40% water-holding capacity treatment at both anthesis and filling stage. Soil water content and plant growth stage had significant (p < 0.0001) effects on concentrations of phenanthrene, anthracene and pyrene in winter wheat. When exposed to 0, 15, 60, and 150 mg kg^-1 Σ₃PAHs in soils, Σ₃PAHs concentrations in the grains under 60% water-holding capacity treatment were 46.6%, 69.9%, 89.5% and 81.7% of those under 80% water-holding capacity treatment, respectively. The highest concentrations of Σ₃PAHs in the crop were recorded at anthesis stage. The distribution of PAHs in different tissues of wheat varied among different soil water treatments and plant growth stages. The present study indicated that optimizing soil water content during winter wheat production could apparently reduce concentrations of Σ₃PAHs in grains via influence root uptake of Σ₃PAHs and translocation of Σ₃PAHs from stem or leaf into grain, suggesting the potential of water management to cope with PAHs contamination in crops growing on PAHs contaminated soils.

Characterization of polycyclic aromatic hydrocarbon (PAHs) source profiles in urban PM2.5 fugitive dust: A large-scale study for 20 Chinese cites

Polycyclic aromatic hydrocarbons (PAHs) in road dust (RD) and construction dust (CD) in PM_2.5 were quantified in the samples collected in 20 Chinese cities. The PAHs profiles in urban PM_2.5 fugitive dusts were determined and their potential health risks were evaluated. Seven geographical regions in China were identified as northwest China (NWC), the North China Plain (NCP), northeast China (NEC), central China (CC), south China (SC), southwest China (SWC), and east China (EC). The overall average concentrations of total quantified PAHs (ΣPAHs) were 23.2 ± 18.9 and 22.8 ± 29.6 μg·g^-1 in RD and CD of PM_2.5, indicating that severe PAHs pollution to urban fugitive dusts in China. The differences of ΣPAHs between RD and CD were minor in northern and central regions of China but much larger in southern and east regions. The ƩPAHs for RD displayed a pattern of "high in northern and low in southern", and characterized by large abundance of high molecular weights (HMWs) PAHs, indicating that vehicle emission was the predominant pollution origin. Additionally, higher diagnostic ratios of fluoranthene/(fluoranthene + pyrene) in NCP, CC, and SWC suggest critical contributions of biomass burning and coal combustion for RD in these areas. In comparison, gasoline combustion was the major pollution source for CD PAHs in NWC, NCP, NEC, and CC, whereas industrial emissions such as cement production and iron smelting had strong impacts in the heavy industrial regions. The total benzo[a]pyrene (BaP) carcinogenic potency concentrations (BaP_TEQ) for RD and CD both showed the lowest in SC (0.05 and 0.07, respectively) and the highest in NCP (10.99 and 7.67, respectively). The highest and lowest incremental life cancer risks (ILCR) were found in NCP and SC, coinciding with the spatial distributions of ambient PAHs levels. The total CD-related cancer risks for adults and children (~10^-4) suggest high potential health risks in NCP, SWC, and NWC, whereas the evaluated values in EC and SC indicate virtual safety (≤10^-6).

Quantification, source apportionment and risk assessment of polycyclic aromatic hydrocarbons in sediments from Mokolo and Blood Rivers in Limpopo Province, South Africa

The presence of polycyclic aromatic hydrocarbons (PAHs) in the environment is of major concern since some of these compounds are highly persistent, toxic (causing cancer) and wide spread pollutants. The objective of this study was to evaluate the levels of PAHs in sediment samples collected from Blood and Mokolo Rivers in Limpopo Province, South Africa. The PAHs in sediments were extracted using optimized microwave-assisted extraction (MAE) method. The quantification of sixteen (16) PAHs in sediments was done by gas chromatography-flame ionization detector (GC-FID). The levels of PAHs recorded in sediment samples from Blood River ranged between 0.015 and 3.25 mg kg^-1. The concentrations of PAHs obtained in sediments from Mokolo River (0.047 to 52.7 mg kg^-1) were higher than those recorded in sediments from Blood River. The PAHs ratios indicated that both pyrogenic and petrogenic could be the sources of these compounds in both rivers. Toxic equivalency factors (TEFs) and benzo(a)pyrene equivalent (BaPE) were used to estimate the potential human health risk of PAHs in quantitative terms. The assessment of ecotoxicological risk indicated that the sediment samples collected from Mokolo River are at high toxicity risk while sediments from Blood River are at low sediment toxicity risk.

Heavy metals and organic compounds contamination in leachates collected from Deir Kanoun Ras El Ain dump and its adjacent canal in South Lebanon

Environmental pollution generated from uncontrolled dumping is a major problem in Lebanon due to the lack of proper waste management plans. Deir Kanoun Ras El Ain is the village that harbors the worst dumps in Lebanon. Wastewater leachates of this dump influx into an adjacent nearby canal used for irrigation and drinking purposes. The aim of this study is to assess the concentrations of heavy metals (Pb, Cd, As, and Hg) and the presence of organic compounds (phthalates, bisphenol A, and polycyclic aromatic hydrocarbons (PAHs)) in water samples collected from two different sites around the dump and two canal sites during winter and summer seasons. The concentrations of heavy metals were determined using atomic absorption spectrophotometry, while the identification of the extracted organic compounds was performed using High Performance Liquid Chromatography coupled to Mass Spectrometry (HPLC–MS). The carried analyses revealed that water samples collected from dump and canal were heavily polluted by Cd, As, Hg, phthalates, bisphenol A, and PAHs caused by pyrogenic and petrogenic sources. The concentrations of the found heavy metals were far above the maximum tolerable levels set by different guidelines. The findings suggest that the studied water sources are not safe for irrigation and drinking. The serious implications of dumping wastes on the health of inhabitants recall for an immediate employment of efficient waste management policies to resolve this problem.

AHR and GPER mediate the stimulatory effects induced by 3-methylcholanthrene in breast cancer cells and cancer-associated fibroblasts (CAFs)

BACKGROUND

The chemical carcinogen 3-methylcholanthrene (3MC) binds to the aryl hydrocarbon receptor (AHR) that regulates the expression of cytochrome P450 (CYP) enzymes as CYP1B1, which is involved in the oncogenic activation of environmental pollutants as well as in the estrogen biosynthesis and metabolism. 3MC was shown to induce estrogenic responses binding to the estrogen receptor (ER) α and stimulating a functional interaction between AHR and ERα. Recently, the G protein estrogen receptor (GPER) has been reported to mediate certain biological responses induced by endogenous estrogens and environmental compounds eliciting an estrogen-like activity.

METHODS

Molecular dynamics and docking simulations were performed to evaluate the potential of 3MC to interact with GPER. SkBr3 breast cancer cells and cancer-associated fibroblasts (CAFs) derived from breast tumor patients were used as model system. Real-time PCR and western blotting analysis were performed in order to evaluate the activation of transduction mediators as well as the mRNA and protein levels of CYP1B1 and cyclin D1. Co-immunoprecipitation studies were performed in order to explore the potential of 3MC to trigger the association of GPER with AHR and EGFR. Luciferase assays were carried out to determine the activity of CYP1B1 promoter deletion constructs upon 3MC exposure, while the nuclear shuttle of AHR induced by 3MC was assessed through confocal microscopy. Cell proliferation stimulated by 3MC was determined as biological counterpart of the aforementioned experimental assays. The statistical analysis was performed by ANOVA.

RESULTS

We first ascertained by docking simulations the ability of 3MC to interact with GPER. Thereafter, we established that 3MC activates the EGFR/ERK/c-Fos transduction signaling through both AHR and GPER in SkBr3 cells and CAFs. Then, we found that these receptors are involved in the up-regulation of CYP1B1 and cyclin D1 as well as in the stimulation of growth responses induced by 3MC.

CONCLUSIONS

In the present study we have provided novel insights regarding the molecular mechanisms by which 3MC may trigger a physical and functional interaction between AHR and GPER, leading to the stimulation of both SkBr3 breast cancer cells and CAFs. Altogether, our results indicate that 3MC may engage both GPER and AHR transduction pathways toward breast cancer progression.

Expression levels of circulating microRNAs-126, -155, and -145 in Mexican women exposed to polycyclic aromatic hydrocarbons through biomass fuel use

Human exposure to polycyclic aromatic hydrocarbons (PAHs) has been considered a risk determinant for the development of cardiovascular diseases (CVD). Therefore, the aim of this study was to assess expression levels of vascular-related miRNAs, miR-126, miR-155, and miR-145, in plasma from women (aged 19-81 years) exposed (n = 100) and non-exposed (n = 20) to PAHs via biomass combustion smoke.1-hydroxypyrene (1-OHP) was determined in urine as a biomarker of exposure to PAHs using high-resolution liquid chromatography. Plasma expression levels of proposed miRNAs were determined by quantitative real-time PCR. Additionally, traditional risk factors (age, blood pressure, serum lipid profile, blood glucose, and among others) associated with CVD were evaluated. Urinary 1-OHP concentrations and plasma expression levels of miR-126 and miR-155 were significantly higher (P < 0.05) in women using wood as a fuel source in their homes (indoor) compared to women from the reference group (non-exposed to biomass smoke). Besides, multivariate linear regression analyses revealed that miR-126[β = 0.61; 95% confidence interval (0.32-0.90)] and miR-155 [β = 0.45; 95% confidence interval (0.13-0.84)] expression levels were significantly associated with urinary 1-OHP concentrations after being adjusted by traditional risk factors (P < 0.05). In contrast, no significant relationship was found between miR-145 and urinary 1-OHP levels. Furthermore, miRNAs assessed in this investigation are associated with CVD events. Consequently, actions to reduce exposure to PAHs in the evaluated population are warranted. Environ. Mol. Mutagen. 60:546-558, 2019. © 2019 Wiley Periodicals, Inc.

Cigarette butts: An overlooked source of PAHs in the environment?

Cigarette butts (CBs) are the most common littered objects in the environment and may contain high amounts of polycylic aromatic hydrocarbons (PAHs) from incomplete tobacco leave burning. But to date there is no comprehensive study on environmental emissions of PAHs by CBs. So the main aim of this study was to compare the concentration levels of 16 PAHs in freshly smoked CBs and CBs from the environment (collected from urban streets and river areas) with different exposure times to the environment. The results showed that the mean concentration levels of 4 PAHs including naphthalene, acenaphthylene, acenaphthene, and fluorene were significantly higher in the freshly smoked CB samples compared to the street samples and were the lowest in the river samples. Considering the number of CBs annually littered, considerable amounts of these 4 PAHs may be released to the environment, which may be a threat to the quality of water resources.