Prenatal exposure to polycyclic aromatic hydrocarbons, benzo[a]pyrene-DNA adducts, and genomic DNA methylation in cord blood

Prenatal exposure to Benzo[a]pyrene affects maternal-fetal outcomes via placental apoptosis

Prenatal exposure to Benzo[a]pyrene (BaP) has been suggested to increase the risk of adverse pregnancy outcomes. However, the role of placental apoptosis on BaP reproductive toxicity is poorly understood. We conducted a maternal animal model of C57BL/6 wild-type (WT) and transformation-related protein 53 (Trp53) heterozygous knockout (p53KO) mice, as well as a nested case-control study involving 83 women with PB and 82 term birth from a birth cohort on prenatal exposure to BaP and preterm birth (PB). Pregnant WT and p53KO mice were randomly allocated to BaP treatment and control groups, intraperitoneally injected of low (7.8 mg/kg), medium (35 mg/kg), and high (78 mg/kg) doses of 3,4-BaP per day and equal volume of vegetable oil, from gestational day 10.5 until delivery. Results show that high-dose BaP treatment increased the incidence of preterm birth in WT mice. The number of fetal deaths and resorptions increased with increasing doses of BaP exposure in mice. Notably, significant reductions in maternal and birth weights, increases in placental weights, and decrease in the number of livebirths were observed in higher-dose BaP groups in dose-dependent manner. We additionally observed elevated p53-mediated placental apoptosis in higher BaP exposure groups, with altered expression levels of p53 and Bax/Bcl-2. In case-control study, the expression level of MMP2 was increased among women with high BaP exposure and associated with the increased risk of all PB and moderate PB. Our study provides the first evidence of BaP-induced reproductive toxicity and its adverse effects on maternal-fetal outcomes in both animal and population studies.

Gestational exposure to environmental chemicals and epigenetic alterations in the placenta and cord blood mononuclear cells

Background

Exposure to environmental chemicals such as phthalates, phenols, and polycyclic aromatic hydrocarbons (PAHs) during pregnancy can increase the risk of adverse newborn outcomes. We explored the associations between maternal exposure to select environmental chemicals and DNA methylation in cord blood mononuclear cells (CBMC) and placental tissue (maternal and fetal sides) to identify potential mechanisms underlying these associations.

Method

This study included 75 pregnant individuals who planned to give birth at the University of Cincinnati Hospital between 2014 and 2017. Maternal urine samples during the delivery visit were collected and analyzed for 37 biomarkers of phenols (12), phthalates (13), phthalate replacements (4), and PAHs (8). Cord blood and placenta tissue (maternal and fetal sides) were also collected to measure the DNA methylation intensities using the Infinium HumanMethylation450K BeadChip. We used linear regression, adjusting for potential confounders, to assess CpG-specific methylation changes in CBMC (n = 54) and placenta [fetal (n = 67) and maternal (n = 68) sides] associated with gestational chemical exposures (29 of 37 biomarkers measured in this study). To account for multiple testing, we used a false discovery rate q-values < 0.05 and presented results by limiting results with a genomic inflation factor of 1±0.5. Additionally, gene set enrichment analysis was conducted using the Kyoto Encyclopedia of Genes and Genomics pathways.

Results

Among the 29 chemical biomarkers assessed for differential methylation, maternal concentrations of PAH metabolites (1-hydroxynaphthalene, 2-hydroxyfluorene, 4-hydroxyphenanthrene, 1-hydroxypyrene), monocarboxyisononyl phthalate, mono-3-carboxypropyl phthalate, and bisphenol A were associated with altered methylation in placenta (maternal or fetal side). Among exposure biomarkers associated with epigenetic changes, 1-hydroxynaphthalene, and mono-3-carboxypropyl phthalate were consistently associated with differential CpG methylation in the placenta. Gene enrichment analysis indicated that maternal 1-hydroxynaphthalene was associated with lipid metabolism and cellular processes of the placenta. Additionally, mono-3-carboxypropyl phthalate was associated with organismal systems and genetic information processing of the placenta.

Conclusion

Among the 29 chemical biomarkers assessed during delivery, 1-hydroxynaphthalene and mono-3-carboxypropyl phthalate were associated with DNA methylation in the placenta.

Supplementary Information

The online version contains supplementary material available at 10.1186/s43682-024-00027-7.

Associations of co-exposure to polycyclic aromatic hydrocarbons and lead (Pb) with IGF1 methylation in peripheral blood of preschool children from an e-waste recycling area

BACKGROUND

Childhood exposure to polycyclic aromatic hydrocarbons (PAHs) or lead (Pb) is associated with epigenetic modifications. However, the effects of their co-exposures on IGF1 (Insulin-like growth factor 1) methylation and the potential role in child physical growth are unclear.

METHODS

From our previous children study (N = 238, ages of 3-6), 75 children with higher total concentrations of urinary ten hydroxyl PAH metabolites (∑10OH-PAHs) from an e-waste recycling area, Guiyu, and 75 with lower ∑10OH-PAHs from Haojiang (reference area) were included. Pb and IGF1 P2 promoter methylation in peripheral blood were also measured. Multivariable linear regression analyses were performed to estimate individual associations, overall effects and interactions of co-exposure to OH-PAHs and Pb on IGF1 methylation were further explored using Bayesian kernel machine regression.

RESULTS

Methylation of IGF1 (CG-232) was lower (38.00 vs. 39.74 %, P < 0.001), but of CG-207 and CG-137 were higher (59.94 vs. 58.41 %; 57.60 vs. 56.28 %, both P < 0.05) in exposed children than the reference. The elevated urinary 2-OHPhe was associated with reduced methylation of CG-232 (B = -0.051, 95 % CI: -0.096, -0.005, P < 0.05), whereas blood Pb was positively associated with methylation of CG-108 (B = 0.106, 95 %CI: 0.013, 0.199, P < 0.05), even after full adjustment. Methylations of CG-224 and 218 significantly decreased when all OH-PAHs and Pb mixtures were set at 35th - 40th and 45th - 55th percentile compared to when all fixed at 50th percentile. There were bivariate interactions of co-exposure to the mixtures on methylations of CG-232, 224, 218, and 108. Methylations correlated with height, weight, were observed in the exposed children.

CONCLUSIONS

Childhood co-exposure to high PAHs and Pb from the e-waste may be associated with IGF1 promoter methylation alterations in peripheral blood. This, in turn, may interrupt the physical growth of preschool children.

Effects and mechanisms of polycyclic aromatic hydrocarbons in inflammatory skin diseases

Polycyclic aromatic hydrocarbons (PAHs) are hydrocarbons characterized by the presence of multiple benzene rings. They are ubiquitously found in the natural environment, especially in environmental pollutants, including atmospheric particulate matter, cigarette smoke, barbecue smoke, among others. PAHs can influence human health through several mechanisms, including the aryl hydrocarbon receptor (AhR) pathway, oxidative stress pathway, and epigenetic pathway. In recent years, the impact of PAHs on inflammatory skin diseases has garnered significant attention, yet many of their underlying mechanisms remain poorly understood. We conducted a comprehensive review of articles focusing on the link between PAHs and several inflammatory skin diseases, including psoriasis, atopic dermatitis, lupus erythematosus, and acne. This review summarizes the effects and mechanisms of PAHs in these diseases and discusses the prospects and potential therapeutic implications of PAHs for inflammatory skin diseases.

Prenatal polycyclic aromatic hydrocarbon exposure and asthma at age 8-9 years in a multi-site longitudinal study

BACKGROUND AND AIM

Studies suggest prenatal exposure to polycyclic aromatic hydrocarbons (PAHs) may influence wheezing or asthma in preschool-aged children. However, the impact of prenatal PAH exposure on asthma and wheeze in middle childhood remain unclear. We investigated these associations in socio-demographically diverse participants from the ECHO PATHWAYS multi-cohort consortium.

METHODS

We included 1,081 birth parent-child dyads across five U.S. cities. Maternal urinary mono-hydroxylated PAH metabolite concentrations (OH-PAH) were measured during mid-pregnancy. Asthma at age 8-9 years and wheezing trajectory across childhood were characterized by caregiver reported asthma diagnosis and asthma/wheeze symptoms. We used logistic and multinomial regression to estimate odds ratios of asthma and childhood wheezing trajectories associated with five individual OH-PAHs, adjusting for urine specific gravity, various maternal and child characteristics, study site, prenatal and postnatal smoke exposure, and birth year and season in single metabolite and mutually adjusted models. We used multiplicative interaction terms to evaluate effect modification by child sex and explored OH-PAH mixture effects through Weighted Quantile Sum regression.

RESULTS

The prevalence of asthma in the study population was 10%. We found limited evidence of adverse associations between pregnancy OH-PAH concentrations and asthma or wheezing trajectories. We observed adverse associations between 1/9-hydroxyphenanthrene and asthma and persistent wheeze among girls, and evidence of inverse associations with asthma for 1-hydroxynathpthalene, which was stronger among boys, though tests for effect modification by child sex were not statistically significant.

CONCLUSIONS

In a large, multi-site cohort, we did not find strong evidence of an association between prenatal exposure to PAHs and child asthma at age 8-9 years, though some adverse associations were observed among girls.

Association of urinary polycyclic aromatic hydrocarbon metabolites with gestational diabetes mellitus and gestational hypertension among pregnant women in Southwest China: A cross-sectional study

The association of polycyclic aromatic hydrocarbons (PAHs) with gestational diabetes mellitus (GDM) and gestational hypertension during pregnancy has not yet been established. To investigate the association between PAH exposure and GDM and gestational hypertension, we conducted a cross-sectional study of 4206 pregnant women from the Zunyi birth cohort in southwestern China. Gas chromatography/mass spectrometry was used to detect the urinary levels of 10 monohydroxylated PAHs (OH-PAHs). GDM and gestational hypertension were diagnosed and the relevant information was documented by specialist obstetricians and gynecologists. Logistic regression and restricted cubic spline regression were employed to investigate their single and nonlinear associations. Stratified analyses of pregnancy and body mass index data were conducted to determine their moderating effects on the abovementioned associations. Compared with the first quartile of urinary ∑OH-PAHs, the third or fourth quartile in all study participants was associated with an increased risk of GDM (quartile 3: odds ratio [OR] = 1.35, 95% confidence interval [CI]: 1.03-1.77) and gestational hypertension (quartile 3: OR = 1.88, 95% CI: 1.26-2.81; quartile 4: OR = 1.58, 95% CI: 1.04-2.39), respectively. Nonlinear associations of 1-OH-PYR with GDM (cutoff level: 0.02 μg/g creatinine [Cr]) and 1-OH-PHE with gestational hypertension (cutoff level: 0.06 μg/g Cr) were also observed. In pregnant women with overweight or obesity, 1-OH-PHE and 3-OH-PHE were more strongly associated with gestational hypertension. Our results indicate that exposure to PAH during pregnancy may significantly increase the maternal risks of GDM and gestational hypertension; however, this finding still needs to be confirmed through larger-scale prospective studies and biological evidence.

Quantitative relationships of FAM50B and PTCHD3 methylation with reduced intelligence quotients in school aged children exposed to lead: Evidence from epidemiological and in vitro studies

At present, the application of DNA methylation (DNAm) biomarkers in environmental health risk assessment (EHRA) is more challenging due to the unclearly quantitative relationship between them. We aimed to explore the role of FAM50B and PTCHD3 at the level of signaling pathways, and establish the quantitative relationship between them and children's intelligence quotients (IQs). DNAm of target regions was measured in multiple cell models and was compared with the human population data. Then the dose-response relationships of lead exposure with neurotoxicity and DNAm were established by benchmark dose (BMD) model, followed by potential signaling pathway screening. Results showed that there was a quantitative linear relationship between children's IQs and FAM50B/PTCHD3 DNAm (DNAm between 51.40 % - 78.78 % and 31.41 % - 74.19 % for FAM50B and PTCHD3, respectively), and this relationship was more significant when children's IQs > 90. The receiver operating characteristic (ROC) and calibration curves showed that FAM50B/PTCHD3 DNAm had a satisfying accuracy and consistency in predicting children's IQs, which was confirmed by sensitivity analysis of gender and CpG site grouping data. In cell experiments, there was also a quantitative linear relationship between FAM50B DNAm and reactive oxygen species (ROS) production, which was mediated by PI3K-AKT signaling pathway. In addition, the lead BMD of ROS was close to that of FAM50B DNAm, suggesting that FAM50B DNAm was a suitable biomarker for the risk assessments of adverse outcomes induced by lead. Taken collectively, these results suggest that FAM50B/PTCHD3 can be applied to EHRA and the prevention/intervention of adverse effects of lead on children's IQs.

Saffron stigma extract and crocin play an important neuroprotective role in therapeutic measures against benzo[a]pyrene-induced behavioral alterations in zebrafish

Saffron is a well-known expensive spice, which has many pharmacological properties against a variety of ailments. Saffron stigma and leaf contain apocarotenoids and bioactive phytochemicals having therapeutic potential against human disorders. Polycyclic aromatic hydrocarbons (PAHs) are one of the most common toxins in today's aquatic environment. Benzo[a]pyrene (B[a]P), a high molecular weight PAHs prototype, and reported as a potent neurotoxicant, which is profoundly contaminating the environment. The present study investigated the therapeutic efficacy of Saffron stigma extracts and crocin, on B[a]P-induced behavioral changes, altered antioxidant activities, and neurodegeneration in zebrafish. The behavioral responses monitored through the light-dark preference test and novel tank diving test suggested that B[a]P treated zebrafish group showed alteration in anxiolytic-like behavior. Animals exhibited their native behavior when treated alone with Saffron Stigma Extract (SSE) and crocin, an apocarotenoid which also reduced the altered behavior induced by B[a]P. The SSE and crocin stimulated the antioxidant activities with an accumulation of reduced glutathione and catalase enzymes, indicating a protective role against B[a]P-induced oxidative stress and behavioral deficits. The histopathological studies showed the percentage change of pyknotic cell counts in the Periventricular Gray Zone region of the Optic Tectum was 1.74 folds high in B[a]P treated animals as compared to control. Furthermore, the treatment of SSE and crocin reduced the pyknosis process induced by B[a]P-mediated neurodegeneration, possibly due to a better protective mechanism. Future studies may reveal the detailed mechanisms of action of potent SSE and crocin like bioactive compounds having neuroprotective potentials against neurodegenerative diseases.

Interleukin-2 gene methylation levels and interleukin-2 levels associated with environmental exposure as risk biomarkers for preterm birth

AIM

To compare interleukin-2 levels (IL-2) and IL-2 gene site 1 methylation levels between preterm newborns (PN) and full-term newborns (FN) and investigate their association with the environmental exposure of their mothers during pregnancy.

METHODS

IL-2 and IL-2 gene site 1 methylation levels were assessed in 50 PN and 56 FN. Newborns' mothers filled in questionnaires about their living and occupational environments, habits, diets, and hobbies.

RESULTS

The mothers of PN were significantly more frequently agrarian/rural residents than the mothers of FN. PN had significantly higher IL-2 levels, and significantly lower methylation of IL-2 gene site 1 levels than FN.

CONCLUSION

IL-2 levels, hypomethylation of the IL-2 gene site 1, and the mother's rural residence (probably due to pesticide exposure) were predictive biomarkers for preterm birth. For the first time, we present the reference values for the methylation of IL-2 gene site 1 in PN and FN, which can be used in the clinical setting and biomonitoring.

Before the first breath: why ambient air pollution and climate change should matter to neonatal-perinatal providers

Common outdoor air pollutants present threats to fetal and neonatal health, placing neonatal-perinatal clinical specialists in an important role for harm reduction through patient counseling and advocacy. Climate change is intertwined with air pollution and influences air quality. There is increasing evidence demonstrating the unique vulnerability in the development of adverse health consequences from exposures during the preconception, prenatal, and early postnatal periods, as well as promising indications that policies aimed at addressing these toxicants have improved birth outcomes. Advocacy by neonatal-perinatal providers articulating the potential impact of pollutants on newborns and mothers is essential to promoting improvements in air quality and reducing exposures. The goal of this review is to update neonatal-perinatal clinical specialists on the key ambient air pollutants of concern, their sources and health effects, and to outline strategies for protecting patients and communities from documented adverse health consequences.

The infiltration of wildfire smoke and its potential dose on pregnant women: Lessons learned from Indonesia wildfires in 2019

The occurrence of wildfires in Indonesia is prevalent during drought seasons. Multiple toxic pollutants emitted from wildfires have deleterious effects on pregnant women. However, the evidence for these on pregnant women was underreported. The study conducted 24-h monitoring of fine particulate matter (PM2.5) concentrations indoors and outdoors in 9 low-income homes in Palangka Raya during the 2019 wildfire season and 6 low-income homes during the 2019 non-wildfire season. A hundred and seventy pregnant women had their PM exposure assessed between July and October 2019 using personal monitors. It was observed that outdoor air pollutant levels were greater than those found indoors without indoor sources. The findings indicate that indoor PM2.5 concentrations were modestly increased by 1.2 times higher than outdoor, suggesting that buildings only partially protected people from exposure during wildfires. The concentrations of PM2.5 were found to be comparatively higher indoors in residential buildings with wood material than in brick houses. The study findings indicate that 8 out of 12 brick houses exhibited a notable RI/O24 h of less than 1 during the wildfires, whereas all I/O24 h ratios during the non-wildfire season were >1, suggesting the influence of indoor sources. Based on the estimation of daily PM2.5 dose, pregnant women received around 21% of their total daily dose during sedentary activity involving cooking. The present research offers empirical support for the view that indoor air quality in low-income households is affected by a complex combination of factors, including wildfire smoke, air tightness, and occupant behaviour. Also, this situation is more likely a potential risk to pregnant women being exposed to wildfire smoke.

Prenatal exposure to polycyclic aromatic hydrocarbons and cognition in early childhood

BACKGROUND

Epidemiological evidence for gestational polycyclic aromatic hydrocarbon (PAH) exposure and adverse child cognitive outcomes is mixed; little is known about critical windows of exposure.

OBJECTIVE

We investigated associations between prenatal PAH exposure and child cognition in a large, multi-site study.

METHODS

We included mother-child dyads from two pooled prospective pregnancy cohorts (CANDLE and TIDES, N = 1,223) in the ECHO-PATHWAYS Consortium. Seven urinary mono-hydroxylated PAH metabolites were measured in mid-pregnancy in both cohorts as well as early and late pregnancy in TIDES. Child intelligence quotient (IQ) was assessed between ages 4-6. Associations between individual PAH metabolites and IQ were estimated with multivariable linear regression. Interaction terms were used to examine effect modification by child sex and maternal obesity. We explored associations of PAH metabolite mixtures with IQ using weighted quantile sum regression. In TIDES, we averaged PAH metabolites over three periods of pregnancy and by pregnancy period to investigate associations between PAH metabolites and IQ.

RESULTS

In the combined sample, PAH metabolites were not associated with IQ after full adjustment, nor did we observe associations with PAH mixtures. Tests of effect modification were null except for the association between 2-hydroxynaphthalene and IQ, which was negative in males (βmales = -0.67 [95%CI:-1.47,0.13]) and positive in females (βfemales = 0.31 [95%CI:-0.52,1.13])(pinteraction = 0.04). In analyses across pregnancy (TIDES-only), inverse associations with IQ were observed for 2-hydroxyphenanthrene averaged across pregnancy (β = -1.28 [95%CI:-2.53,-0.03]) and in early pregnancy (β = -1.14 [95%CI:-2.00,-0.28]).

SIGNIFICANCE

In this multi-cohort analysis, we observed limited evidence of adverse associations of early pregnancy PAHs with child IQ. Analyses in the pooled cohorts were null. However, results also indicated that utilizing more than one exposure measures across pregnancy could improve the ability to detect associations by identifying sensitive windows and improving the reliability of exposure measurement. More research with multiple timepoints of PAH assessment is warranted.

Developmental exposure to polycyclic aromatic hydrocarbons (PAHs): Focus on benzo[a]pyrene neurotoxicity

Polycyclic Aromatic Hydrocarbons (PAHs) are a class of ubiquitous organic compounds produced during the incomplete combustion or pyrolysis of organic material. Dietary source is the main route for PAH human exposure by environmental contamination, food industrial processing or domestic cooking methods. The most studied PAH is benzo[a]pyrene (B[a]P), due to its harmful and multiple effects on human health: in addition to its well-known carcinogenic effects, emerging evidence indicates that B[a]P also induces neurotoxicity earlier and at lower doses than B[a]P-induced carcinogenicity making B[a]P neurotoxicity relevant to human health risk assessment. Developmental neurotoxicity of B[a]P has indeed received increasing attention: both human and experimental studies provide evidence of detrimental effects of prenatal or early postnatal B[a]P exposure, even at low doses. Indeed, in some of the multi-dose animal studies, maximal adverse effects were observed at lower B[a]P doses, according to a non-monotonic dose-response curve typical of endocrine-disrupting compounds. In substantial agreement with epidemiological studies, both rodents and zebrafish developmentally exposed to B[a]P exhibit long-term changes in multiple behavioural domains, in the absence of overt toxicological effects at birth (e.g. body weight and morphologic abnormalities). Notably, most targeted behavioural responses converge on locomotor activity and emotional profile, often, but not always, leading to a disinhibitory/hyperactive profile.

Prenatal polycyclic aromatic hydrocarbon exposure and asthma at age 8-9 years in a multi-site longitudinal study

Background and aim

Studies suggest prenatal exposure to polycyclic aromatic hydrocarbons (PAHs) may influence wheezing or asthma in preschool-aged children. However, the impact of prenatal PAH exposure on asthma and wheeze in middle childhood remain unclear. We investigated these associations in diverse participants from the ECHO PATHWAYS multi-cohort consortium.

Methods

We included 1,081 birth parent-child dyads across five U.S. cities. Maternal urinary mono-hydroxylated PAH metabolite concentrations (OH-PAH) were measured during mid-pregnancy. Asthma at age 8-9 years and wheezing trajectory across childhood were characterized by caregiver reported asthma diagnosis and asthma/wheeze symptoms. We used logistic and multinomial regression to estimate odds ratios of asthma and childhood wheezing trajectories associated with five individual OH-PAHs, adjusting for urine specific gravity, various maternal and child characteristics, study site, prenatal and postnatal smoke exposure, and birth year and season in single metabolite and mutually adjusted models. We used multiplicative interaction terms to evaluate effect modification by child sex and explored OH-PAH mixture effects through Weighted Quantile Sum regression.

Results

The prevalence of asthma in the study population was 10%. We found limited evidence of adverse associations between pregnancy OH-PAH concentrations and asthma or wheezing trajectories. We observed adverse associations between 1/9-hydroxyphenanthrene and asthma and persistent wheeze among girls, and evidence of inverse associations with asthma for 1-hydroxynathpthalene, which was stronger among boys, though tests for effect modification by child sex were not statistically.

Conclusions

In a large, multi-site cohort, we did not find strong evidence of an association between prenatal exposure to PAHs and child asthma at age 8-9 years, though some adverse associations were observed among girls.

Associations between prenatal exposure to polycyclic aromatic hydrocarbons and thyroid hormones in umbilical cord blood

We explored the association between maternal urinary polycyclic aromatic hydrocarbon (PAH) metabolites and thyroid hormones in umbilical cord blood in 120 pairs of pregnant women and newborns. Maternal urinary PAH metabolites were measured using high-performance liquid chromatography with tandem mass spectrometry. Thyroid hormones were measured using a flow fluorescence assay. The dose-response relationship between PAH metabolites and thyroid hormones was analyzed using the generalized linear model and restricted cubic spline model. Results showed that ƩOH PAHs in maternal urine had a negative effect on triiodothyronine (T3). Associations between maternal urinary PAH metabolites and thyroid hormones in umbilical cord blood plasma were observed. Prenatal exposure to PAHs could affect neonatal thyroid hormones, thereby disrupting neonatal thyroid function.

Involvement and targeted intervention of benzo(a)pyrene-regulated apoptosis related proteome modification and muti-drug resistance in hepatocellular carcinoma

During the development of hepatocellular carcinoma (HCC), the mutual adaptation and interaction of HCC cells and the microenvironment play an important role. Benzo(a)pyrene (B[a]P) is a common environmental pollutant, which can induce the initiation of various malignant tumors, including HCC. However, the effects of B[a]P exposure on progression of HCC and the potential mechanisms remains largely uninvestigated. Here we found that, after the long-term exposure of HCC cells to low dose of B[a]P, it activated glucose-regulated protein 75 (GRP75), which then induced a modification of apoptosis-related proteome. Among them, we identified the X-linked inhibitor of apoptosis protein (XIAP) as a key downstream factor. XIAP further blocked the caspase cascade activation and promoted the acquisition of the anti-apoptosis abilities, ultimately leading to multi-drug resistance (MDR) in HCC. Furthermore, the abovementioned effects were markedly attenuated when we inhibited GRP75 by using 3,4-dihydroxycinnamic acid (caffeic acid, CaA). Collectively, our present study revealed the effects of B[a]P exposure on the progression of HCC, and identified GRP75 was a meaningful factor involved in.

Biodegradation of organic compounds in the coal gangue by Bacillus sp. into humic acid

Coal gangue (CG), one of the world's largest industrial solid wastes produced during coal mining, is extremely difficult to be used owing to its combined contents of clay minerals and organic macromolecules. This study explored a novel process of degrading the harmful organic compounds in the CG into humic acid using a biological method characterized by scanning electron microscope-energy dispersive spectrometer, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and elemental analyzer. The results reveal that adding selected Bacillus sp. to the CG for 40 days can increase the humic acid content by ~ 17 times, reaching 17338.17 mg/kg, which is also the best level for promoting plant growth. FTIR and XPS spectra show that the organic compounds in the CG transforms primarily from C=C to C=O, COOH, and O-H groups, indicating that the organic compounds are gradually oxidized and activated, improving the humic acid concentration of soil. In addition, Bacillus sp. decreases pH and benzo[a]pyrene contents, and increases the content of available nutrients. After microbial degradation, coal gangue can be turned into ecological restoration materials.

Exposure of embryos to phenanthrene impacts the cardiac development in F1 zebrafish larvae and potential reasons

To explore the impact of embryonic exposure to phenanthrene (Phe), a typical tricyclic polycyclic aromatic hydrocarbon, on cardiac development in next generation, fertilized zebrafish embryos were exposed to 0.05, 0.5, 5 and 50 nM Phe for 96 h, and then transferred to clear water and raised to adulthood. The cardiac development in F1 larvae generated by adult females or males mated with unexposed zebrafish was assessed. Malformation and dysfunction of the heart, such as increased heart rate, arrhythmia, enlarged heart and abnormal contraction, were shown in both paternal and maternal F1 larvae. A greater impact on the distance between the sinus venosus and bulbus arteriosus was exhibited in maternal F1 larvae, while paternal F1 larvae displayed a more severe impact on heart rate and arrhythmia. The transcription of genes related to cardiac development was disturbed in F1 larvae. DNA methylation levels in the promoter of some genes were associated with their transcription. The expression of acetylated histone H3K9Ac and H3K14Ac in maternal F1 larvae was no significantly changed, but was significantly downregulated in paternal F1 larvae, which might be associated with the downregulated transcription of tbx5. These results indicate that exposure to Phe during embryogenesis adversely affects cardiac development in F1 generation, and the effects and toxic mechanisms showed sex-linked hereditary differences, highlighting the risk of Phe exposure in early life to heart health in next generation.

Effects of H19/SAHH/DNMT1 on the oxidative DNA damage related to benzo[a]pyrene exposure

The mechanisms that long noncoding RNA (lncRNA) H19 binding to S-adenosylhomocysteine hydrolase (SAHH) interacted with DNA methyltransferase 1 (DNMT1) and then regulated DNA damage caused by polycyclic aromatic hydrocarbons (PAHs) remain unclear. A total of 146 occupational workers in a Chinese coke-oven plant in 2014 were included in the final analyses. We used high-performance liquid chromatography mass spectrometry (HPLC-MS) equipped to detect urine biomarkers of PAHs exposure, including 2-hydroxynaphthalene (2-NAP), 2-hydroxyfluorene (2-FLU), 9-hydroxyphenanthrene (9-PHE) and 1-hydroxypyrene (1-OHP). The levels of SAM and SAH in plasma were detected by HPLC-ultraviolet. By constructing various BEAS-2B cell models exposed to 16 μM benzo[a]pyrene (BaP) for 24 h, toxicological parameters reflecting distinct mechanisms were evaluated. We documented that urinary 1-hydroxypyrene (1-OHP) levels were positively associated with blood H19 RNA expression (OR: 1.51, 95% CI: 1.03-2.19), but opposite to plasma SAHH activity (OR: 0.63, 95% CI: 0.41-0.98) in coke oven workers. Moreover, by constructing various BEAS-2B cell models exposed to benzo[a]pyrene (BaP), we investigated that H19 binding to SAHH exaggerated DNMT1 expressions and activity. Suppression of H19 enhanced the interaction of SAHH and DNMT1 in BaP-treated cells, decreased eight-oxoguanine DNA glycosylase 1 (OGG1) methylation, reduced oxidative DNA damage and lessened S phase arrest. However, SAHH or DNMT1 single knockdown and SAHH/DNMT1 double knockdown showed the opposite trend. A H19/SAHH/DNMT1 axis was involved in OGG1 methylation, oxidative DNA damage and cell cycle arrest by carcinogen BaP.

PAH-induced metabolic changes related to inflammation in childhood asthma

Epidemiological studies have shown that PAHs may exert adverse effects on childhood asthma. However, the underlying molecular mechanism remains to be fully elucidated. This study aimed to investigate this process in view of metabolic pathways, especially one-carbon metabolism and tryptophan metabolism. Fifty asthmatic children and 50 control subjects were recruited for this study. Serum IgE and IL-17A levels were detected by ELISA. Serum PAH concentrations were measured by GC-MS. One-carbon-related metabolites and tryptophan metabolites were determined by UPLC-Orbitrap-MS. DNA methylation was analyzed by bisulfite sequencing PCR. ChIP assays were used to examine H3K4me3 enrichment on IL-17A gene. Multivariable linear regression was performed to evaluate the association between PAHs and childhood asthma mediated by intermediators. HE staining in lung tissue, IgE and IL-17A in BALF, metabolic profiles in urine, and Ahr, Il-17a, and Cyp1a1 gene expression were determined in PAH-exposed mice. Serum Fla level was associated with childhood asthma (OR = 1.380, 95% CI: 1.063-1.792), and had a great effect on one-carbon metabolites, especially SAH, SAM, and Ser, which exerted significant mediation effects on the relationship between the Fla concentration and asthma. Moreover, we did find significant mediation effects between serum Fla and asthma by LINE-1 DNA methylation and H3K4me3 levels in the IL-17A promoter region. The differential Trp metabolites, such as Trp, tryptamine, IA, IAA, indole, IAld, and IAAld, indicated that asthmatic children had increased indole-AhR pathway. Mediation analysis failed to show a mediator effect of Trp metabolites in the association between PAHs and childhood asthma. An animal study confirmed that PAH exposure increased methylation levels, and altered Trp metabolite-AhR-IL-17A axis, which may be influenced by gender. PAHs disturbed one-carbon metabolism to influence the methyl group refilling DNA methylation and histone methylation, and disturbed tryptophan metabolism to regulate Th17-cell differentiation, which may elevate serum IL-17A concentration in asthmatic children.

Prenatal exposure to polycyclic aromatic hydrocarbons is not associated with behavior problems in preschool and early school-aged children: A prospective multi-cohort study

BACKGROUND

Epidemiological study findings are inconsistent regarding associations between prenatal polycyclic aromatic hydrocarbon (PAH) exposures and childhood behavior. This study examined associations of prenatal PAH exposure with behavior at age 4-6 years in a large, diverse, multi-region prospective cohort. Secondary aims included examination of PAH mixtures and effect modification by child sex, breastfeeding, and child neighborhood opportunity.

METHODS

The ECHO PATHWAYS Consortium pooled 1118 mother-child dyads from three prospective pregnancy cohorts in six U.S. cities. Seven PAH metabolites were measured in prenatal urine. Child behavior was assessed at age 4-6 using the Total Problems score from the Child Behavior Checklist (CBCL). Neighborhood opportunity was assessed using the socioeconomic and educational scales of the Child Opportunity Index. Multivariable linear regression was used to estimate associations per 2-fold increase in each PAH metabolite, adjusted for demographic, prenatal, and maternal factors and using interaction terms for effect modifiers. Associations with PAH mixtures were estimated using Weighted Quantile Sum Regression (WQSR).

RESULTS

The sample was racially and sociodemographically diverse (38% Black, 49% White, 7% Other; household-adjusted income range $2651-$221,102). In fully adjusted models, each 2-fold increase in 2-hydroxynaphthalene was associated with a lower Total Problems score, contrary to hypotheses (b = -0.80, 95% CI = -1.51, -0.08). Associations were notable in boys (b = -1.10, 95% CI = -2.11, -0.08) and among children breastfed 6+ months (b = -1.31, 95% CI = -2.25, -0.37), although there was no statistically significant evidence for interaction by child sex, breastfeeding, or neighborhood child opportunity. Associations were null for other PAH metabolites; there was no evidence of associations with PAH mixtures from WQSR.

CONCLUSION

In this large, well-characterized, prospective study of mother-child pairs, prenatal PAH exposure was not associated with child behavior problems. Future studies characterizing the magnitude of prenatal PAH exposure and studies in older childhood are needed.

Cellular mechanisms linking to outdoor and indoor air pollution damage during pregnancy

Pregnancies are a critical window period for environmental influences over the mother and the offspring. There is a growing body of evidence associating indoor and outdoor air pollution exposure to adverse pregnancy outcomes such as preterm birth and hypertensive disorders of pregnancy. Particulate matter (PM) could trigger oxi-inflammation and could also reach the placenta leading to placental damage with fetal consequences. The combination of strategies such as risk assessment, advise about risks of environmental exposures to pregnant women, together with nutritional strategies and digital solutions to monitor air quality can be effective in mitigating the effects of air pollution during pregnancy.

Phthalate acid esters and polycyclic aromatic hydrocarbons concentrations with their determining factors among Chinese pregnant women: A focus on dietary patterns

BACKGROUND

Pregnant women are susceptible to adverse health effects associated with phthalate acid esters (PAEs) and polycyclic aromatic hydrocarbons (PAHs), and diet is a significant exposure source. Little is known about the contributions of dietary patterns during pregnancy to the exposure variability of these environmental contaminants.

OBJECTIVES

To identify dietary patterns in relation to PAEs and PAHs exposure in the Chinese pregnant population.

METHODS

Dietary data and urinary concentrations of environmental pollutants were obtained from 1190 pregnant women in the Tongji Birth Cohort (TJBC). PAEs and PAHs were measured in spot urine samples. Food intake was assessed using a food-frequency questionnaire. Dietary patterns were constructed by principal component analysis (PCA). Through PCA, we also extracted three chemical mixture scores that represent different co-exposure patterns of PAEs and PAHs. Multiple linear regression models were adopted to identify predictors of PAEs and PAHs exposure.

RESULTS

Four dietary patterns were identified by PCA that explained 44.9 % of the total variance of food intake. We found egg-dairy products pattern, whole grain-tuber crop pattern, and meat-aquatic products pattern were positively associated with specific pollutants exposure. In contrast, fruit-nut-vegetable pattern was negatively correlated with PAEs and PAHs exposure. Every SD increase in this pattern score was associated with 14.36 % reduced mono(2-ethyl-5-oxohexyl) phthalate (MEOHP) (95 % CI: -24.50 ~ -2.96, p-trend = 0.01), 10.86 % reduced 2-hydroxynaphthalene (2-OHNap) (95 % CI: -20.07 ~ -0.60, p-trend = 0.04), 19.35 % reduced 9-hydroxyphenanthrene (9-OHPhe) (95 % CI: -34.49 ~ -0.70, p-trend = 0.01), and 8.33 % reduced scores of PAHs group (95 % CI: -15.97 ~ -0.10, p-trend = 0.02). In addition, disposable tableware usage and passive smoking were suggested as potentially modifiable sources of PAEs and PAHs exposure, respectively.

CONCLUSION

Adhering to egg-dairy products pattern, whole grain-tuber crop pattern, and meat-aquatic products pattern may be related to increased PAEs and PAHs exposure, while following fruit-nut-vegetable pattern seems to correlate with a lower burden of such exposure.

Maternal exposure to urinary polycyclic aromatic hydrocarbons (PAH) in pregnancy and childhood asthma in a pooled multi-cohort study

BACKGROUND

Prenatal exposure to polycyclic aromatic hydrocarbons (PAH) may increase risk of pediatric asthma, but existing human studies are limited.

OBJECTIVES

We estimated associations between gestational PAHs and pediatric asthma in a diverse US sample and evaluated effect modification by child sex, maternal asthma, and prenatal vitamin D status.

METHODS

We pooled two prospective pregnancy cohorts in the ECHO PATHWAYS Consortium, CANDLE and TIDES, for an analytic sample of N = 1296 mother-child dyads. Mono-hydroxylated PAH metabolites (OH-PAHs) were measured in mid-pregnancy urine. Mothers completed the International Study on Allergies and Asthma in Childhood survey at child age 4-6 years. Poisson regression with robust standard errors was used to estimate relative risk of current wheeze, current asthma, ever asthma, and strict asthma associated with each metabolite, adjusted for potential confounders. We used interaction models to assess effect modification. We explored associations between OH-PAH mixtures and outcomes using logistic weighted quantile sum regression augmented by a permutation test to control Type 1 errors.

RESULTS

The sociodemographically diverse sample spanned five cities. Mean (SD) child age at assessment was 4.4 (0.4) years. While there was little evidence that either individual OH-PAHs or mixtures were associated with outcomes, we observed effect modification by child sex for most pairs of OH-PAHs and outcomes, with adverse associations specific to females. For example, a 2-fold increase in 2-hydroxy-phenanthrene was associated with current asthma in females but not males (RRfemale = 1.29 [95 % CI: 1.09, 1.52], RRmale = 0.95 [95 % CI: 0.79, 1.13]; pinteraction = 0.004). There was no consistent evidence of modification by vitamin D status or maternal asthma.

DISCUSSION

This analysis, the largest cohort study of gestational PAH exposure and childhood asthma to date, suggests adverse associations for females only. These preliminary findings are consistent with hypothesized endocrine disruption properties of PAHs, which may lead to sexually dimorphic effects.

Ambient air pollution during pregnancy and DNA methylation in umbilical cord blood, with potential mediation of associations with infant adiposity: The Healthy Start study

BACKGROUND

Prenatal exposure to ambient air pollution has been associated with adverse offspring health outcomes. Childhood health effects of prenatal exposures may be mediated through changes to DNA methylation detectable at birth.

METHODS

Among 429 non-smoking women in a cohort study of mother-infant pairs in Colorado, USA, we estimated associations between prenatal exposure to ambient fine particulate matter (PM2.5) and ozone (O3), and epigenome-wide DNA methylation of umbilical cord blood cells at delivery (2010-2014). We calculated average PM2.5 and O3 in each trimester of pregnancy and the full pregnancy using inverse-distance-weighted interpolation. We fit linear regression models adjusted for potential confounders and cell proportions to estimate associations between air pollutants and methylation at each of 432,943 CpGs. Differentially methylated regions (DMRs) were identified using comb-p. Previously in this cohort, we reported positive associations between 3rd trimester O3 exposure and infant adiposity at 5 months of age. Here, we quantified the potential for mediation of that association by changes in DNA methylation in cord blood.

RESULTS

We identified several DMRs for each pollutant and period of pregnancy. The greatest number of significant DMRs were associated with third trimester PM2.5 (21 DMRs). No single CpGs were associated with air pollutants at a false discovery rate <0.05. We found that up to 8% of the effect of 3rd trimester O3 on 5-month adiposity may be mediated by locus-specific methylation changes, but mediation estimates were not statistically significant.

CONCLUSIONS

Differentially methylated regions in cord blood were identified in association with maternal exposure to PM2.5 and O3. Genes annotated to the significant sites played roles in cardiometabolic disease, immune function and inflammation, and neurologic disorders. We found limited evidence of mediation by DNA methylation of associations between third trimester O3 exposure and 5-month infant adiposity.

Prenatal exposure to air pollution is associated with altered brain structure, function, and metabolism in childhood

BACKGROUND

Prenatal exposure to air pollution disrupts cognitive, emotional, and behavioral development. The brain disturbances associated with prenatal air pollution are largely unknown.

METHODS

In this prospective cohort study, we estimated prenatal exposures to fine particulate matter (PM_2.5 ) and polycyclic aromatic hydrocarbons (PAH), and then assessed their associations with measures of brain anatomy, tissue microstructure, neurometabolites, and blood flow in 332 youth, 6-14 years old. We then assessed how those brain disturbances were associated with measures of intelligence, ADHD and anxiety symptoms, and socialization.

RESULTS

Both exposures were associated with thinning of dorsal parietal cortices and thickening of postero-inferior and mesial wall cortices. They were associated with smaller white matter volumes, reduced organization in white matter of the internal capsule and frontal lobe, higher metabolite concentrations in frontal cortex, reduced cortical blood flow, and greater microstructural organization in subcortical gray matter nuclei. Associations were stronger for PM_2.5 in boys and PAH in girls. Youth with low exposure accounted for most significant associations of ADHD, anxiety, socialization, and intelligence measures with cortical thickness and white matter volumes, whereas it appears that high exposures generally disrupted these neurotypical brain-behavior associations, likely because strong exposure-related effects increased the variances of these brain measures.

CONCLUSIONS

The commonality of effects across exposures suggests PM_2.5 and PAH disrupt brain development through one or more common molecular pathways, such as inflammation or oxidative stress. Progressively higher exposures were associated with greater disruptions in local volumes, tissue organization, metabolite concentrations, and blood flow throughout cortical and subcortical brain regions and the white matter pathways interconnecting them. Together these affected regions comprise cortico-striato-thalamo-cortical circuits, which support the regulation of thought, emotion, and behavior.

Influences of polycyclic aromatic hydrocarbon on the epigenome toxicity and its applicability in human health risk assessment

The existence of polycyclic aromatic hydrocarbons (PAHs) in ambient air is an escalating concern worldwide because of their ability to cause cancer and induce permanent changes in the genetic material. Growing evidence implies that during early life-sensitive stages, the risk of progression of acute and chronic diseases depends on epigenetic changes initiated by the influence of environmental cues. Several reports deciphered the relationship between exposure to environmental chemicals and epigenetics, and have known toxicants that alter the epigenetic states. Amongst PAHs, benzo[a]pyrene (B[a]P) is accepted as a group 1 cancer-causing agent by the International Agency for the Research on Cancer (IARC). B[a]P is a well-studied pro-carcinogen that is metabolically activated by the aryl hydrocarbon receptor (AhR)/cytochrome P450 pathway. Cytochrome P450 plays a pivotal role in the stimulation step, which is essential for DNA adduct formation. Accruing evidence suggests that epigenetic alterations assume a fundamental part in PAH-promoted carcinogenesis. This interaction between PAHs and epigenetic factors results in an altered profile of these marks, globally and locus-specific. Some of the epigenetic changes due to exposure to PAHs lead to increased disease susceptibility and progression. It is well understood that exposure to environmental carcinogens, such as PAH triggers disease pathways through changes in the genome. Several evidence reported due to the epigenome-wide association studies, that early life adverse environmental events may trigger widespread and persistent variations in transcriptional profiling. Moreover, these variations respond to DNA damage and/or a consequence of epigenetic modifications that need further investigation. Growing evidence has associated PAHs with epigenetic variations involving alterations in DNA methylation, histone modification, and micro RNA (miRNA) regulation. Epigenetic alterations to PAH exposure were related to chronic diseases, such as pulmonary disease, cardiovascular disease, endocrine disruptor, nervous system disorder, and cancer. This hormetic response gives a novel perception concerning the toxicity of PAHs and the biological reaction that may be a distinct reliance on exposure. This review sheds light on understanding the latest evidence about how PAHs can alter epigenetic patterns and human health. In conclusion, as several epigenetic change mechanisms remain unclear yet, further analyses derived from PAHs exposure must be performed to find new targets and disease biomarkers. In spite of the current limitations, numerous evidence supports the perception that epigenetics grips substantial potential for advancing our knowledge about the molecular mechanisms of environmental toxicants, also for predicting health-associated risks due to environmental circumstances exposure and individual susceptibility.

Neurotoxicity of Polycyclic Aromatic Hydrocarbons: A Systematic Mapping and Review of Neuropathological Mechanisms

Several studies present the neurotoxic effects of polycyclic aromatic hydrocarbons (PAHs), a class of environmental pollutants capable of causing neurological deficits. However, a collective review approach to this research topic is scarce. This study presents the effect of PAHs on the central nervous system using a bibliometric approach. The neuropathological mechanisms of PAHs are also highlighted. Published articles were searched for in the Scopus and Web of Science databases from January 1979 to December 2020 using the keywords ‘polycyclic aromatic hydrocarbons’ and ‘neurotoxicity’. The total number of documents retrieved from both databases was 338. Duplicated documents (80) were excluded and 258 articles were used for the final analysis. Our findings revealed that there has been a significant increase in research outputs on this topic in the last ten years. The countries with the highest scientific productivity in this area are USA, China, France and Italy. The result also showed that, in the past few years, global scientific output in research relating to PAH neurotoxicity focused on neurodegeneration, cholinergic function, neurodevelopmental toxicity, behavioural studies, oxidative stress, neuroprotection and therapeutic intervention using different experimental models, including zebrafish, neuronal cell lines, Caenorhabditis elegans and rats. Recent studies also revealed the neuroprotective roles of some natural products against PAH-induced neurotoxicity. However, more investigation involving clinical trials is required to emphasize the observed neurotoxic effects.

Intersections of the microbiome and early neurodevelopment

Our resident microbes influence nearly all aspects of our biological systems. In particular, the maternal and early life microbiota is uniquely positioned to influence the development of the nervous system, and alterations to the gut microbiota, or dysbiosis, during this critical time in early life can have long-lasting negative effects on health. The question of how the maternal and early life microbiota shapes neurodevelopment is the topic of numerous investigations. Here, we discuss two possible, but not necessarily independent, hypotheses: (1) the maternal microbiota during pregnancy regulates the metabolites that are important for fetal development, (2) maternal microbiota seeded to offspring at birth and early postnatal days programs offspring immune and brain development, and regulates key molecules for postnatal brain development. In this chapter, we provide an overview of the impact of the microbiota on brain and behavior, introduce the maternal gut and vaginal microbiome during pregnancy, and discuss current understandings of microbiome in the context of developmental origins of health and disease. We consider novel translational insights that harness the multitude of microbes and microbial metabolites for prevention or treatment of neurological disorders.

DNA methylation: a potential mediator between air pollution and metabolic syndrome

Given the global increase in air pollution and its crucial role in human health, as well as the steep rise in prevalence of metabolic syndrome (MetS), a better understanding of the underlying mechanisms by which environmental pollution may influence MetS is imperative. Exposure to air pollution is known to impact DNA methylation, which in turn may affect human health. This paper comprehensively reviews the evidence for the hypothesis that the effect of air pollution on the MetS is mediated by DNA methylation in blood. First, we present a summary of the impact of air pollution on metabolic dysregulation, including the components of MetS, i.e., disorders in blood glucose, lipid profile, blood pressure, and obesity. Then, we provide evidence on the relation between air pollution and endothelial dysfunction as one possible mechanism underlying the relation between air pollution and MetS. Subsequently, we review the evidence that air pollution (PM, ozone, NO₂ and PAHs) influences DNA methylation. Finally, we summarize association studies between DNA methylation and MetS. Integration of current evidence supports our hypothesis that methylation may partly mediate the effect of air pollution on MetS.

Benzo[a]pyrene—Environmental Occurrence, Human Exposure, and Mechanisms of Toxicity

Benzo[a]pyrene (B[a]P) is the main representative of polycyclic aromatic hydrocarbons (PAHs), and has been repeatedly found in the air, surface water, soil, and sediments. It is present in cigarette smoke as well as in food products, especially when smoked and grilled. Human exposure to B[a]P is therefore common. Research shows growing evidence concerning toxic effects induced by this substance. This xenobiotic is metabolized by cytochrome P450 (CYP P450) to carcinogenic metabolite: 7β,8α-dihydroxy-9α,10α-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE), which creates DNA adducts, causing mutations and malignant transformations. Moreover, B[a]P is epigenotoxic, neurotoxic, and teratogenic, and exhibits pro-oxidative potential and causes impairment of animals’ fertility. CYP P450 is strongly involved in B[a]P metabolism, and it is simultaneously expressed as a result of the association of B[a]P with aromatic hydrocarbon receptor (AhR), playing an essential role in the cancerogenic potential of various xenobiotics. In turn, polymorphism of CYP P450 genes determines the sensitivity of the organism to B[a]P. It was also observed that B[a]P facilitates the multiplication of viruses, which may be an additional problem with the widespread COVID-19 pandemic. Based on publications mainly from 2017 to 2022, this paper presents the occurrence of B[a]P in various environmental compartments and human surroundings, shows the exposure of humans to this substance, and describes the mechanisms of its toxicity.

The effect of maternal polycyclic aromatic hydrocarbons exposure and methylation levels of CHDs-candidate genes on the risk of congenital heart diseases

OBJECTIVE

To evaluate the impact of maternal exposure to polycyclic aromatic hydrocarbons (PAHs) and methylation levels of CHDs-candidate genes on the risk of congenital heart diseases (CHDs), and the effect of PAHs exposure on DNA methylation states.

METHODS

A case-control study involving 60 mother -fetus pairs was performed by measuring 1-OHPG concentration in maternal urine and methylation levels of 20 CHDs-candidate genes in cord bloods. Logistic regression models were applied to determine the effect of maternal PAHs exposure and fetal methylation levels on the risk of CHDs. Spearman correlation was performed to correlate PAHs exposure and methylation levels.

RESULTS

Maternal higher PAHs exposure was associated with the risk of CHDs (aOR = 3.245, 95% CI: 1.060, 9.937) or some subtypes. The methylation levels of 23 amplicons within 11 genes exhibited significant differences between CHDs and controls. Higher methylation of NKX2-5_M1 was associated with decreased risk of CHDs (aOR=0.182, 95% CI:0.034, 0.983). No significant correlations were found between 1-OHPG concentration and methylation levels of NKX2-5_M1.

CONCLUSIONS

Maternal PAHs exposure was linked with CHDs. Higher methylation of the upstream sequence of NKX2-5 promoter decreased the risk of CHDs. There was no correlation between maternal PAHs exposure and the methylation level of NKX2-5. This article is protected by copyright. All rights reserved.

Impacts of Life-Time Exposure of Arsenic, Cadmium and Fluoranthene on the Earthworms’ L. rubellus Global DNA Methylation as Detected by msAFLP

This study reports on the effects of long-term exposure to the metals arsenic (As), cadmium (Cd) and the polycyclic aromatic hydrocarbon fluoranthene on the survival, growth, development and DNA methylation status of the earthworm Lumbricus rubellus. Exposures to the three chemicals were conducted over their whole juvenile developmental period from egg to adult. Significant effects on one or more measured endpoints were found for all three chemicals. Arsenic had no effect on survival, but had a significant effect on growth rates at concentrations of 36 mg/kg or higher and also slowed the rate of maturation. Cadmium significantly reduced juvenile survival at 500 mg/kg, juvenile growth at 148 mg/kg and maturation rates at all tested concentrations. Fluoranthene had no effect on survival or the developmental period, but did significantly reduce growth rates at 800 mg/kg. Effects at these concentrations are consistent with the known effects of these three chemicals on earthworms from previous studies conducted mainly with Eisenia fetida. Both As and Cd had no effect on DNA methylation patterning in earthworms measured at the end of the exposure. Fluoranthene was shown, for the first time. to have an effect on a species’ DNA methylation levels. These results suggest that apical phenotypic changes for As and Cd are not necessarily associated with changes in DNA methylation profiles. However, exposure to the organic chemical fluoranthene influenced DNA methylation patterns, suggesting wider remodelling of the epigenome for this chemical.

Association Studies of Environmental Exposures, DNA Methylation and Children’s Cognitive, Behavioral, and Mental Health Problems

Introduction: Prenatal environmental exposures have been associated with children’s cognitive, behavioral, and mental health problems, and alterations in DNA methylation have been hypothesized as an underlying biological mechanism. However, when testing this hypothesis, it is often difficult to overcome the problem of multiple comparisons in statistical testing when evaluating a large number of developmental outcomes and DNA methylation sites as potential mediators. The objective of this study is to implement a ‘meet-in-the-middle’ approach with a sequential roadmap to address this concern.

Methods: In the Columbia Center for Children’s Environmental Health birth cohort study, we implemented a 5-step sequential process for identifying CpG sites that mediate associations between prenatal environmental exposures and cognitive, behavioral, and mental health problems as measured by the Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV) and the Child Behavior Checklist (CBCL). These steps include 1) the identification of biological pathways that are relevant to each outcome of interest; 2) selection of a set of genes and CpGs on genes that are significantly associated with the outcomes; 3) identification of exposures that are significantly associated with selected CpGs; 4) examination of exposure-outcome relationships among those where significant CpGs were identified; and 5) mediation analysis of the selected exposures and corresponding outcomes. In this study, we considered a spectrum of environmental exposure classes including environmental phenols, pesticides, phthalates, flame retardants and air pollutants.

Results: Among all considered exposures and outcomes, we found one CpG site (cg27510182) on gene (DAB1) that potentially mediates the effect of exposure to PAH on CBCL social problems at children aged 7.

Conclusion: This ‘meet-in-the-middle’ approach attenuates concerns regarding multiple comparisons by focusing on genes and pathways that are biologically relevant for the hypothesis.

Global DNA Methylation in Cord Blood as a Biomarker for Prenatal Lead and Antimony Exposures

DNA methylation is an epigenetic mechanism for gene expression modulation and can be used as a predictor of future disease risks. A prospective birth cohort study was performed to clarify the effects of neurotoxicants on child development, namely, the Tohoku Study of Child Development, in Japan. This study aimed to evaluate the association of prenatal exposure to five toxic metals—arsenic, cadmium, mercury, lead (Pb), antimony (Sb), and polychlorinated biphenyls (PCBs, N = 166)—with global DNA methylation in umbilical cord blood DNA. DNA methylation markers, 5-methyl-2′-deoxycytidine (mC) and 5-hydroxymethyl-2′-deoxycytidine (hmC), were determined using liquid chromatography-tandem mass spectrometry. The mC content in cord blood DNA was positively correlated with Pb and Sb levels (r = 0.435 and 0.288, respectively) but not with cord blood PCBs. We also observed significant positive correlations among Pb levels, maternal age, and hmC content (r = 0.155 and 0.243, respectively). The multiple regression analysis among the potential predictors demonstrated consistent positive associations between Pb and Sb levels and mC and hmC content. Our results suggest that global DNA methylation is a promising biomarker for prenatal exposure to Pb and Sb.

GPR61 methylation in cord blood: a potential target of prenatal exposure to air pollutants

To explore the impact of air pollutants exposure during pregnancy on infant DNA methylation, we identified correlated methylated genes in maternal and cord blood samples using the Illumina Human Methylation 27 k BeadChip. Quantitative methylation-specific PCR (QMS-PCR) was performed to validate the target gene methylation pattern in 568 participants. Then the association between air pollutants exposure and DNA methylation level in the target gene was investigated. The GPR61 gene with a higher methylation level both in mothers and newborns was identified as the target gene, and we found a positive mother-infant DNA methylation correlation in the promoter region of GPR61. Air pollutants exposure during entire pregnancy was associated with maternal and infant GPR61 DNA methylation. After adjusting confounding variables, maternal air pollutants exposure was still associated with infant GPR61 DNA methylation. In summary, GPR61 methylation in cord blood may be a potential target of prenatal exposure to air pollutants.

Maternal and early life exposures and their potential to influence development of the microbiome

At the dawn of the twentieth century, the medical care of mothers and children was largely relegated to family members and informally trained birth attendants. As the industrial era progressed, early and key public health observations among women and children linked the persistence of adverse health outcomes to poverty and poor nutrition. In the time hence, numerous studies connecting genetics ("nature") to public health and epidemiologic data on the role of the environment ("nurture") have yielded insights into the importance of early life exposures in relation to the occurrence of common diseases, such as diabetes, allergic and atopic disease, cardiovascular disease, and obesity. As a result of these parallel efforts in science, medicine, and public health, the developing brain, immune system, and metabolic physiology are now recognized as being particularly vulnerable to poor nutrition and stressful environments from the start of pregnancy to 3 years of age. In particular, compelling evidence arising from a diverse array of studies across mammalian lineages suggest that modifications to our metagenome and/or microbiome occur following certain environmental exposures during pregnancy and lactation, which in turn render risk of childhood and adult diseases. In this review, we will consider the evidence suggesting that development of the offspring microbiome may be vulnerable to maternal exposures, including an analysis of the data regarding the presence or absence of a low-biomass intrauterine microbiome.

Polycyclic Aromatic Hydrocarbons (PAHs) Sample Preparation and Analysis in Beverages: A Review

The monitoring of food contaminants is of interests to both food regulatory bodies and the consumers. This literature review covers polycyclic aromatic hydrocarbons (PAHs) with regard to their background, sources of exposures, and occurrence in food and environment as well as health hazards. Furthermore, analytical methods focusing on the analysis of PAHs in tea, coffee, milk, and alcoholic samples for the last 16 years are presented. Numerous experimental methods have been developed aiming to obtain better limits of detections (LODs) and percent recoveries as well as to reduce solvent consumption and laborious work. These include information such as the selected PAHs analyzed, food matrix of PAHs, methods of extraction, cleanup procedure, LOD, limits of quantitation (LOQ), and percent recovery. For the analysis of tea, coffee, milk, and alcoholic samples, a majority of the research papers focused on the 16 US Environmental Protection Agency PAHs, while PAH4, PAH8, and methylated PAHs were also of interests. Extraction methods range from the classic Soxhlet extraction and liquid–liquid extraction to newer methods such as QuEChERS, dispersive solid-phase microextraction, and magnetic solid-phase extraction. The cleanup methods involved mainly the use of column chromatography and SPE filled with either silica or Florisil adsorbents. Gas chromatography and liquid chromatography coupled with mass spectrometry or fluorescence detectors are the main analytical instruments used. A majority of the selected combined methods used are able to achieve LODs and percent recoveries in the ranges of 0.01–5 ug/kg and 70–110%, respectively, for the analysis of tea, coffee, milk, and alcoholic samples.

The preliminary investigation of potential response biomarkers to PAHs exposure on childhood asthma

BACKGROUND

Exposure to polycyclic aromatic hydrocarbons (PAHs) is a potential risk factor for asthma prevalence. This study aims to explore whether PAHs exposure is associated with childhood asthma by altering microbial diversity and metabolic profiles.

METHODS

Thirty children with asthma and 30 children as control in Nanjing, China were recruited. Urinary 1-hydroxypyrene (1-OHPyr) level was determined by UPLC-Orbitrap-MS as a PAHs exposure biomarker. Logistic regression was conducted to investigate the association between 1-OHPyr and childhood asthma. Microbial diversity was analyzed by 16S rRNA gene sequencing. Metabolic profiles were obtained by UPLC-Orbitrap-MS methods. Differential microbiota and metabolites were screened and selected as response biomarkers or intermediates. Mediation analysis was conducted to assess the association between PAHs and asthma mediated by intermediates.

RESULTS

Participating children with and without asthma aged 6.43 ± 2.23 years. The urinary 1-OHPyr level ranged from 0.10 to 1.51 μmol/mol (creatinine corrected) in the participants. The urinary 1-OHPyr level was associated with childhood asthma (OR = 7.21, 95% CI: 1.03-50.42 per 1 μmol/mol unit). Microbial diversity was decreased in the group with asthma and there was a significant shift in the abundance of Proteobacteria (at the phylum level), Veillonella and Prevotella (at the genus level). The enrichment pathway analysis showed that differentially expressed metabolites were involved in purine metabolism, amino acid metabolism, and lipid and fatty acid metabolism. The urinary 1-OHPyr level was associated with the abundance of Actinomyces sp. oral clone IO076 and 7-methylguanine that showed a mediation effect on the association between urinary 1-OHPyr levels and childhood asthma by mediation analysis.

CONCLUSIONS

Urinary 1-OHPyr exposure was associated with childhood asthma, microbial diversity, and metabolic profiles. Microbial diversity and metabolic profiles may be intermediates as response biomarkers to PAHs exposure in childhood asthma. Further research is needed to confirm these study results and determine the underlying mechanism.

Aspirin ameliorates the cognition impairment in mice following benzo[a]pyrene treatment via down-regulating BDNF IV methylation

Benzo[a]pyrene (B[a]P) is neurotoxic, however, the mechanisms remain unclear and there is no effective prevention. Available evidence suggests a role of DNA methylation in B[a]P-induced neurotoxicity. This study investigated the brain-derived neurotrophic factor (BDNF) IV methylation in the development of and aspirin intervention against B[a]P's neurotoxicity in mice and HT22 cells. Mice were intraperitoneally treated with solvent or B[a]P (0.5, 2, and 10 mg/kg b.w.) for 60 days. An intervention group was treated simultaneously with B[a]P (10 mg/kg, i.p.) and aspirin (10 mg/kg, daily water-drinking). The treated mice showed a dose-dependent cognitive and behavioral impairment, and cerebral cell apoptosis, which were alleviated by aspirin co-treatment. Following B[a]P treatment, DNA methyltransferase (DNMTs) and BDNF IV hypermethylation were increased in the cerebral cortex of mice compared to controls, while significant decreases were found in BDNF IV and BDNF mRNA, and BDNF protein levels. Aspirin co-treatment rescued DNMTs activation and BDNF IV hypermethylation, and mitigated the recession in BDNF mRNA and protein induced by B[a]P treatment. Similar results were shown in HT22 cells. These findings reveal a critical role of BDNF IV methylation in the neurotoxicity of B[a]P, and demonstrate a promising prevention of aspirin against B[a]P-induced cognitive impairment via inhibiting BDNF IV hypermethylation.

Influence of Benzo(a)pyrene on Different Epigenetic Processes

Epigenetic changes constitute one of the processes that is involved in the mechanisms of carcinogenicity. They include dysregulation of DNA methylation processes, disruption of post-translational patterns of histone modifications, and changes in the composition and/or organization of chromatin. Benzo(a)pyrene (BaP) influences DNA methylation and, depending on its concentrations, as well as the type of cell, tissue and organism it causes hypomethylation or hypermethylation. Moreover, the exposure to polyaromatic hydrocarbons (PAHs), including BaP in tobacco smoke results in an altered methylation status of the offsprings. Researches have indicated a potential relationship between toxicity of BaP and deregulation of the biotin homeostasis pathway that plays an important role in the process of carcinogenesis. Animal studies have shown that parental-induced BaP toxicity can be passed on to the F1 generation as studied on marine medaka (Oryzias melastigma), and the underlying mechanism is likely related to a disturbance in the circadian rhythm. In addition, ancestral exposure of fish to BaP may cause intergenerational osteotoxicity in non-exposed F3 offsprings. Epidemiological studies of lung cancer have indicated that exposure to BaP is associated with changes in methylation levels at 15 CpG; therefore, changes in DNA methylation may be considered as potential mediators of BaP-induced lung cancer. The mechanism of epigenetic changes induced by BaP are mainly due to the formation of CpG-BPDE adducts, between metabolite of BaP-BPDE and CpG, which leads to changes in the level of 5-methylcytosine. BaP also acts through inhibition of DNA methyltransferases activity, as well as by increasing histone deacetylases HDACs, i.e., HDAC2 and HDAC3 activity. The aim of this review is to discuss the mechanism of the epigenetic action of BaP on the basis of the latest publications.

Methylmercury and Polycyclic Aromatic Hydrocarbons in Mediterranean Seafood: A Molecular Anthropological Perspective

Eating seafood has numerous health benefits; however, it constitutes one of the main sources of exposure to several harmful environmental pollutants, both of anthropogenic and natural origin. Among these, methylmercury and polycyclic aromatic hydrocarbons give rise to concerns related to their possible effects on human biology. In the present review, we summarize the results of epidemiological investigations on the genetic component of individual susceptibility to methylmercury and polycyclic aromatic hydrocarbons exposure in humans, and on the effects that these two pollutants have on human epigenetic profiles (DNA methylation). Then, we provide evidence that Mediterranean coastal communities represent an informative case study to investigate the potential impact of methylmercury and polycyclic aromatic hydrocarbons on the human genome and epigenome, since they are characterized by a traditionally high local seafood consumption, and given the characteristics that render the Mediterranean Sea particularly polluted. Finally, we discuss the challenges of a molecular anthropological approach to this topic.

Prenatal exposure to polycyclic aromatic hydrocarbons could increase the risk of low birth weight by affecting the DNA methylation states in a Chinese cohort

Polycyclic aromatic hydrocarbons (PAHs), as a kind of endocrine disruptors, can enter the fetus body cross the placental barrier from prenatal PAHs exposure to cause adverse birth outcomes. However, it is controversial association between prenatal PAHs exposure and low birth weight (LBW) of their infants. So the present study aimed to estimate the effects of prenatal PAHs exposure during the pregnancy on the risk of LBW in a Chinese cohort through modifying the DNA methylation states. A longitudinal prospective study with 407 pregnant women was established from May to October 2019. The prenatal PAHs exposure during the pregnancy was assessed using the internal dose such as the PAHs metabolites and PAH-DNA adducts in the umbilical cord blood. The methylation levels of genomic DNA and growth-related genes (IGF1 and IGF2) were assessed, while the expressions of these genes were both determined by RT-PCR and Elisa methods. The growth outcomes and relevant Z-scores were recorded at birth. The correlations between the DNA methylation status and concentrations of PAHs, expression levels of growth-related genes and body weight/WAZ were investigated as the measures. According to the PAH-DNA adducts, the subjects were divided into two groups: PAHs-exposed group (PAH-DNA adducts>0, n = 55) and non-exposed group (PAH-DNA adducts = 0, n = 352). Compared with the non-exposed group, it displayed marked decreased birth weight, and increased concentrations of PAHs and DNA methylation levels of the global genomic, IGF1 and IGF2 with their lower expressions in the PAHs-exposed group. These hypermethylation (global genomic, CpG14 and CpG15 of IGF1, and CpG14 of IGF2) were positively correlated with the contents of PAHs in the umbilical cord blood, and negatively correlated with the growth outcomes and their expressions. Totally, prenatal PAHs exposures may contribute to an increased risk of LBW of their infants by modulating the DNA methylation states of genomic DNA and growth-related genes (IGF1 and IGF2) in the umbilical cord blood, which could provide the prenatal prevention of PAHs exposure from possible environmental media except from the occupation and tobacco usage to ensure the health of their infants.

Exposure to polycyclic aromatic hydrocarbons, DNA methylation and heart rate variability among non-current smokers

Polycyclic aromatic hydrocarbons (PAHs) exposure is associated with heart rate variability (HRV) reduction, a widely used marker of cardiovascular autonomic dysfunction. The role of DNA methylation in the relationship between PAHs exposure and decreased HRV is largely unknown. This study aims to explore epigenome-wide DNA methylation changes associated with PAHs exposure and further evaluate their associations with HRV alternations among non-current smokers. We measured 10 mono-hydroxylated PAHs (OH-PAHs) in urine and DNA methylation levels in blood leukocytes among participants from three panels of Chinese non-current smokers (152 in WHZH, 99 in SY, and 53 in COW). We conducted linear regression analyses between DNA methylation and OH-PAHs metabolites with adjustment for age, gender, body mass index, drinking, blood cell counts, and surrogate variables in each panel separately, and combined the results by using inverse-variance weighted fixed-effect meta-analysis to obtain estimates of effect size. The median value of total OH-PAHs ranged from 0.92 × 10^-2 in SY panel (62.6% men) to 13.82 × 10^-2 μmol/mmol creatinine in COW panel (43.4% men). The results showed that methylation levels of cg18223625 (COL20A1) and cg07805771 (SLC16A1) were significantly or marginally significantly associated with urinary 2-hydroxynaphthalene [β(SE) = 0.431(0.074) and 0.354(0.068), FDR = 0.016 and 0.056, respectively], while methylation level of cg09235308 (PLEC1) was positively associated with urinary total OH-PAHs [β(SE) = 0.478(0.079), FDR = 0.004]. Hypermethylations of cg18223625, cg07805771, and cg09235308 were inversely associated with HRV indices among the WHZH and COW non-current smokers. However, we did not observe significant epigenome-wide associations for the other 9 urinary OH-PAHs. These findings provide new evidence that PAHs exposure is linked to differential DNA methylation, which may help better understand the influences of PAHs exposure on HRV alternations.

Acute benzo[a]pyrene exposure induced oxidative stress, neurotoxicity and epigenetic change in blood clam Tegillarca granosa

The blood clam (Tegillarca granosa) is being developed into a model bivalve mollusc for assessing and monitoring marine pollution on the offshore seabed. However, the information on the response of blood clam to PAHs, an organic pollutant usually deposited in submarine sediment, remains limited. Herein, we employed multiple biomarkers, including histological changes, oxidative stress, neurotoxicity and global DNA methylation, to investigate the effects of 10 and 100 μg/L Bap exposure on the blood clams under laboratory conditions, as well as the potential mechanisms. Acute Bap exposure can induce significant morphological abnormalities in gills as shown through hematoxylin–eosin (H.E) staining, providing an intuitive understanding on the effects of Bap on the structural organization of the blood clams. Meanwhile, the oxidative stress was significantly elevated as manifested by the increase of antioxidants activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and glutathione-s-transferase (GST), lipid peroxidation (LPO) level and 8-hydroxy-2′-deoxyguanosine (8-OHdG) content. The neurotoxicity was also strengthened by Bap toxicity manifested as inhibited acetylcholinesterase (AChE) and choline acetyltransferase (ChAT) activities. In addition, the global DNA methylation level was investigated, and a significant DNA hypomethylation was observed in Bap exposed the blood clam. The correlation analysis showed that the global DNA methylation was negatively correlated with antioxidants (SOD, CAT and POD) activities, but positively correlated choline enzymes (AChE and ChAT) activities. These results collectively suggested that acute Bap exposure can cause damage in gills structures in the blood clam possibly by generating oxidative stress and neurotoxicity, and the global DNA methylation was inhibited to increase the transcriptional expression level of antioxidants genes and consequently elevate antioxidants activities against Bap toxicity. These results are hoped to shed some new light on the study of ecotoxicology effect of PAHs on marine bivalves.

Epigenome-wide DNA methylation signature of benzo[a]pyrene exposure and their mediation roles in benzo[a]pyrene-associated lung cancer development

Benzo[a]pyrene (B[a]P) is a typical carcinogen associated with increased lung cancer risk, but the underlying mechanisms remain unclear. This study aimed to investigate epigenome-wide DNA methylation associated with B[a]P exposure and their mediation effects on B[a]P-lung cancer association in two lung cancer case-control studies of 462 subjects. Their plasma levels of benzo[a]pyrene diol epoxide-albumin (BPDE-Alb) adducts and genome-wide DNA methylations were separately detected in peripheral blood by using enzyme-linked immunosorbent assay (ELISA) and genome-wide methylation arrays. The epigenome-wide meta-analysis was performed to analyze the associations between BPDE-Alb adducts and DNA methylations. Mediation analysis was applied to assess effect of DNA methylation on the B[a]P-lung cancer association. We identified 15 CpGs associated with BPDE-Alb adducts (P_-meta < 1.0 × 10^-5), among which the methylation levels at five loci (cg06245338, cg24256211, cg15107887, cg02211741, and cg04354393 annotated to UBE2O, SAMD4A, ACBD6, DGKZ, and SLFN13, respectively) mediated a separate 38.5%, 29.2%, 41.5%, 47.7%, 56.5%, and a joint 58.2% of the association between BPDE-Alb adducts and lung cancer risk. Compared to the traditional factors [area under the curve (AUC) = 0.788], addition of these CpGs exerted improved discriminations for lung cancer, with AUC ranging 0.828-0.861. Our results highlight DNA methylation alterations as potential mediators in lung tumorigenesis induced by B[a]P exposure.

Children's Greenness Exposure and IQ-Associated DNA Methylation: A Prospective Cohort Study

Epigenetics is known to be involved in regulatory pathways through which greenness exposure influences child development and health. We aimed to investigate the associations between residential surrounding greenness and DNA methylation changes in children, and further assessed the association between DNA methylation and children's intelligence quotient (IQ) in a prospective cohort study. We identified cytosine-guanine dinucleotide sites (CpGs) associated with cognitive abilities from epigenome- and genome-wide association studies through a systematic literature review for candidate gene analysis. We estimated the residential surrounding greenness at age 2 using a geographic information system. DNA methylation was analyzed from whole blood using the HumanMethylationEPIC array in 59 children at age 2. We analyzed the association between greenness exposure and DNA methylation at age 2 at the selected CpGs using multivariable linear regression. We further investigated the relationship between DNA methylation and children's IQ. We identified 8743 CpGs associated with cognitive ability based on the literature review. Among these CpGs, we found that 25 CpGs were significantly associated with greenness exposure at age 2, including cg26269038 (Bonferroni-corrected p ≤ 0.05) located in the body of SLC6A3, which encodes a dopamine transporter. DNA methylation at cg26269038 at age 2 was significantly associated with children's performance IQ at age 6. Exposure to surrounding greenness was associated with cognitive ability-related DNA methylation changes, which was also associated with children's IQ. Further studies are warranted to clarify the epigenetic pathways linking greenness exposure and neurocognitive function.

An Assessment on Ethanol-Blended Gasoline/Diesel Fuels on Cancer Risk and Mortality

Although cancer is traditionally considered a genetic disease, the epigenetic abnormalities, including DNA hypermethylation, histone deacetylation, and/or microRNA dysregulation, have been demonstrated as a hallmark of cancer. Compared with gene mutations, aberrant epigenetic changes occur more frequently, and cellular epigenome is more susceptible to change by environmental factors. Excess cancer risks are positively associated with exposure to occupational and environmental chemical carcinogens, including those from gasoline combustion exhausted in vehicles. Of note, previous studies proposed particulate matter index (PMI) as a measure for gasoline sooting tendency, and showed that, compared with the other molecules in gasoline, 1,2,4-Trimethylbenzene, 2-methylnaphthalene and toluene significantly contribute to PMI of the gasoline blends. Mechanistically, both epigenome and genome are important in carcinogenicity, and the genotoxicity of chemical agents has been thoroughly studied. However, less effort has been put into studying the epigenotoxicity. Moreover, as the blending of ethanol into gasoline substitutes for carcinogens, like benzene, toluene, xylene, butadiene, and polycyclic aromatic hydrocarbons, etc., a reduction of secondary aromatics has been achieved in the atmosphere. This may lead to diminished cancer initiation and progression through altered cellular epigenetic landscape. The present review summarizes the most important findings in the literature on the association between exposures to carcinogens from gasoline combustion, cancer epigenetics and the potential epigenetic impacts of biofuels.

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.

Maternal exposure to phenanthrene during gestation disturbs glucose homeostasis in adult mouse offspring

Epidemiological studies have indicated that polycyclic aromatic hydrocarbons were related to diabetes and insulin resistance. However, studies in mammals on the development of diabetes caused by polycyclic aromatic hydrocarbons are lacking. Pregnant mice were orally exposed to phenanthrene (0, 60 and 600 μg kg^-1 body weight) once every 3 days during gestation. In adult mouse offspring, in-utero phenanthrene exposure caused glucose intolerance and decreased insulin levels in females, while caused elevated fasting blood glucose and insulin levels in males. Serum resistin and interleukin-6 levels were elevated in offspring of both sexes. Serum adiponectin levels were decreased in females but increased in males. The insulin receptor signals were upregulated in the liver and downregulated in the skeletal muscle of F1 females, while they were inhibited in both tissues of F1 males. The visceral fat weight and body weight of the treated mice were not increased, suggesting that phenanthrene is not an obesogen, which is supported by the nonsignificant alteration in pparγ transcription in visceral adipose tissue. The transcription of retn in visceral adipose tissue was upregulated in both sexes, and that of adipoq was downregulated in females but upregulated in males, which were matched with the promoter methylation levels of these genes. The results indicated that phenanthrene exposure during gestation could disturb adipocytokine levels via epigenetic modification in adult offspring, and further influence glucose metabolism. These results might be helpful for understanding nonobesogenic pollutant-induced insulin resistance and preventing against diabetes without obesity.