Co-exposure to polycyclic aromatic hydrocarbons, benzene and toluene and their dose-effects on oxidative stress damage in kindergarten-aged children in Guangzhou, China

Urinary Metabolites of Polycyclic Aromatic Hydrocarbons of Rural Population in Northwestern China: Oxidative Stress and Health Risk Assessment

Polycyclic aromatic hydrocarbon (PAH) exposure is suspected to be linked to oxidative damage. Herein, ten PAH human exposure biomarkers [hydroxylated PAH metabolites (OH-PAHs)] and five oxidative stress biomarkers (OSBs) were detected in urine samples collected from participants living in a rural area (n = 181) in Northwestern China. The median molar concentration of ΣOH-PAHs in urine was 47.0 pmol mL-1. The 2-hydroxynaphthalene (2-OHNap; median: 2.21 ng mL-1) was the dominant OH-PAH. The risk assessment of PAH exposure found that hazard index (HI) values were <1, indicating that the PAH exposure of rural people in Jingyuan would not generate significant cumulative risks. Smokers (median: 0.033) obtained higher HI values than nonsmokers (median: 0.015, p < 0.01), suggesting that smokers face a higher health risk from PAH exposure than nonsmokers. Pearson correlation and multivariate linear regression analysis revealed that ΣOH-PAH concentrations were significant factors in increasing the oxidative damage to deoxyribonucleic acid (DNA) (8-hydroxy-2'-deoxyguanosine, 8-OHdG), ribonucleic acid (RNA) (8-oxo-7,8-dihydroguanine, 8-oxoGua), and protein (o, o'-dityrosine, diY) (p < 0.05). Among all PAH metabolites, only 1-hydroxypyrene (1-OHPyr) could positively affect the expression of all five OSBs (p < 0.05), suggesting that urinary 1-OHPyr might be a reliable biomarker for PAH exposure and a useful indicator for assessing the impacts of PAH exposure on oxidative stress. This study is focused on the relation between PAH exposure and oxidative damage and lays a foundation for the study of the health effect mechanism of PAHs.

Exposure to volatile organic compounds induces cardiovascular toxicity that may involve DNA methylation

Volatile organic compounds (VOCs) are common air pollutants and water contaminants. We previously found maternal exposure to VOCs was associated with offspring congenital heart disease (CHD). However, little information is available about the effects of VOCs on cardiovascular development at embryonic stage and the underlying mechanism remains unclear. In this study, we aimed to investigate the effects of a mixture of six VOCs on cardiovascular development in zebrafish embryos. Embryos were exposed to different concentrations of VOCs mixture (32 mg/L, 64 mg/L and 128 mg/L) for 96 h, cardiovascular abnormalities including elongated heart shape, increased distance between sinus venosus and bulbus arteriosus, slowed circulation and altered heart rate were observed in a dose- and time-dependent manner. Meanwhile, VOCs exposure increased global DNA methylation levels in embryos. Analysis identified hundreds of differentially methylated sites and the enrichment of differentially methylated sites on cardiovascular development. Two differentially methylated-associated genes involved in MAPK pathway, hgfa and ntrk1, were identified to be the potential genes mediating the effects of VOCs. By enzyme-linked immunosorbent assay, altered human serum hgf and ntrk1 levels were detected in abnormal pregnancies exposed to higher VOCs levels with fetal CHD. For the first time, our study revealed exposure to VOCs induced severe cardiovascular abnormalities in zebrafish embryos. The toxicity might result from alterations in DNA methylation and corresponding expression levels of genes involved in MAPK pathway. Our study provides important information for the risk of VOCs exposure on embryonic cardiovascular development.

Development and validation of an HPLC-MS/MS method for the simultaneous analysis of volatile organic compound metabolites, hydroxylated polycyclic aromatic hydrocarbons, and 8-hydroxy-2'-deoxyguanosine in human urine

Humans are widely and concurrently exposed to volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs). However, few studies have reported the internal co-exposure levels of these chemicals in occupational and general populations. Specifically, the associations revealed between the urinary levels of metabolites of VOCs (mVOCs), hydroxylated PAHs (OH-PAHs), and oxidative stress biomarkers for humans remain limited. In this study, a method based on solid-phase extraction (SPE) and liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was developed for the simultaneous analysis of 22 mVOCs, 12 OH-PAHs, and 8-hydroxy-2'-deoxyguanosine (8-OHdG) in human urine samples. The method was validated with all target analyte accuracies and precisions in the range of 76 %-120 % and 1 %-14 % at three levels of spiked urine samples, respectively. The limit of detection (LOD) and limit of quantification (LOQ) of the target analytes were 0.01-0.34 ng/mL and 0.01-7.57 ng/mL, respectively. And the method was applied to measure urinary levels of target analytes from 38 petrochemical workers in Guangzhou, South China. Except for 3-hydroxy-benzo[a]pyrene, all target analytes were detected in the urine samples. The average levels were 0.05-12.6 ng/mL for individual OH-PAHs, 0.20-73620 ng/mL for individual mVOCs, and 1.00 ng/mL for 8-OHdG. Additionally, 3-hydroxy-phenanthrene, 1-hydroxy-pyrene, 6-hydroxy-chrysene, N-acetyl-S-(trichlorovinyl)-L-cysteine, 2-methylhippuric acid, thiodiacetic acid, trans, trans-Muconic acid, and N-acetyl-S-(3,4-dihydroxybutyl)-L-cysteine had statistically significant positive effects on 8-OHdG levels, while 1-hydroxy-naphthalene, 1,2-dihydroxybenzene, and hippuric acid showed a negative effect on 8-OHdG, indicating these metabolites could lead to synergistic or antagonistic oxidative DNA damage. This study provides a robust analytical method that permits a comprehensive assessment of co-exposure to PAHs and VOCs and their potential adverse health effects.

Reintroducing a keystone bioturbator can facilitate microbial bioremediation in urban polluted sediments

Anthropogenic environmental stressors have significantly reduced biodiversity and the capacity of remnant natural habitats to deliver ecosystem functions and services in urban areas. To mitigate these impacts and recover biodiversity and function, ecological restoration strategies are needed. While habitat restoration is proliferating in rural and peri-urban areas, strategies purposely designed to succeed under the environmental, social and political pressures of urban areas are lacking. Here, we propose that ecosystem health in marine urban areas can be improved by restoring biodiversity to the most dominant habitat, unvegetated sediments. We reintroduced a native ecosystem engineer, the sediment bioturbating worm Diopatra aciculata, and assessed their effects on microbial biodiversity and function. Results showed that worms can affect the diversity of microbes, but effects varied between locations. Worms caused shifts in microbial community composition and function at all locations. Specifically, the abundance of microbes capable of chlorophyll production (i.e. benthic microalgae) increased and the abundance of microbes capable of methane production decreased. Moreover, worms increased the abundances of microbes capable of denitrification in the site with lowest sediment oxygenation. Worms also affected microbes capable of degrading the polycyclic aromatic hydrocarbon toluene, although the direction of that effect was site-specific. This study provides evidence that a simple intervention such as the reintroduction of a single species can enhance sediment functions important for the amelioration of contamination and eutrophication, although further studies are needed to understand the variation in outcomes between sites. Nevertheless, restoration strategies targeting unvegetated sediments provide an opportunity to combat anthropogenic stressors in urban ecosystems and may be used for precondition before more traditional forms of habitat restoration such as seagrass, mangrove and shellfish restoration.

Developing a profile of urinary PAH metabolites among Chinese populations in the 2010s

Polycyclic aromatic hydrocarbons (PAHs) pose significant health risks. However, no nationwide cohort has been established to consistently record biomonitoring data on PAH exposure in the Chinese population. Biomonitoring data from 56 published studies were combined in this study to develop a profile of urinary PAH metabolites among Chinese population in the 2010s. The stacked column charts described the composition profiles of hydroxylated PAHs (OH-PAHs) in general, special, and occupational populations. Hydroxynaphthalene (OH-Nap) and hydroxyfluorene (OH-Flu) accounted for more than half of the urinary OH-PAH in general and special populations. The urine of the occupational populations contained a significant amount of hydroxyphenanthrene (OH-Phe) and 1-hydroxypyrene (1-OHPyr). Furthermore, this study analyzed the distribution profiles of non-occupationally exposed populations, such as spatial distribution, age distribution, and trends over time. The population of the Southern region had higher urinary OH-PAH concentrations than the population of the Northern region. Adults (45-55 years old) had the highest level of internal PAH exposure. Between 2010 and 2018, the overall trend of urinary OH-PAHs in Chinese general populations decreased. The cumulative distribution function (CDF) revealed that 1-OHNap and 1-OHPyr were better at distinguishing internal PAH exposure among different populations. The sum of OH-Flu and OH-Phe in urine can be used to assess the impact of indoor and outdoor environments on human exposure to PAHs. Our findings suggest that more emphasis should be placed on collecting biomonitoring data for adults of all ages (particularly in the Northern region) and vulnerable populations. In conclusion, this study advocates for the establishment of a nationwide cohort study of Chinese populations as soon as possible in the future to evaluate the Chinese population's exposure to environmental contaminants.

Association between polycyclic aromatic hydrocarbon exposure and hypertension among the U.S. adults in the NHANES 2003-2016: A cross-sectional study

The global burden of hypertension, the major cause of cardiovascular disease (CVD) globally, remains unresolved. Exposure to PM2.5 has been linked to hypertension (HTN) in adults and the elderly globally according to previous studies. Nonetheless, evidence on the association of polycyclic aromatic hydrocarbon (PAH) exposure and HTN risk in the general adult population in the United States was limited. To investigate the relationship between PAH exposure and HTN in adults in the United States, cross-sectional data during 2003 and 2016 from the National Health and Nutrition Examination Survey (NHANES) on a stratified multistage random sample of the civilian non-institutionalized population were utilized. After eliminating individuals with incomplete information of interest, the final analysis contained 8951 subjects aged ≥20. In the multivariate logistic regression model, 1-hydroxynaphthalene and 2-hydroxyfluorene were found positively associated with increased risk of HTN among overall participants after adjusting for the covariates. 1-hydroxynaphthalene and 2-hydroxynaphthalene showed positive associations with HTN risk among overweight participants. In the Bayesian kernel machine regression (BKMR) model, 1-hydroxynaphthalene and 2-hydroxyfluorene presented great importance to HTN risk among overall individuals. In the male subgroup analyses by BKMR, 2-hydroxyfluorene presented a positive effect on HTN risk when the remaining OH-PAHs were set at their 25th, 50th, and 75th percentile. Our findings highlight the complexities of estimating the risk of HTN associated with mixed PAH exposure, and additional longitudinal studies are required to determine the exact link between PAH exposure and HTN risk, as well as the underlying mechanisms.

The association of co-exposure to polycyclic aromatic hydrocarbon and phthalates with blood cell-based inflammatory biomarkers in children: A panel study

The association of co-exposure to polycyclic aromatic hydrocarbons (PAHs) and phthalates (PAEs) with blood cell-based inflammatory biomarkers is largely unknown. We conducted a panel study of 144 children aged 4-12 years, with up to 3 repeated visits across 3 seasons. For each visit, we collected the first-morning urine for 4 consecutive days and fasting blood on the day of physical examination. We developed a gas chromatography/tandem mass spectrometry method to detect the metabolites of 10 PAHs (OH-PAHs) and 10 PAEs (mPAEs) in urine samples. We employed linear mixed-effects models to evaluate the individual associations of each OH-PAH and mPAE with blood cell-based inflammatory biomarkers over different lag times. Bayesian kernel machine regression (BKMR) and quantile g-computation were used to evaluate the overall associations of OH-PAHs and mPAEs mixtures with blood cell-based inflammatory biomarkers. After multiple adjustments, we found positive associations of summed hydroxylphenanthrene (∑OHPHE), summed OH-PAHs, and mono-n-butyl phthalate with inflammatory biomarkers such as neutrophil count, neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, and the systemic immune-inflammation index (SII) at lag 0 (the day of physical examination). Each 1% increase in ∑OHPHE was related to a 0.18% (95% confidence interval: 0.10%, 0.25%) increase in SII, which was the strongest among the above associations. The results of BKMR and quantile g-computation suggested that co-exposure to PAHs and PAEs mixture was associated with an elevated white blood cell count, neutrophil count, neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, and SII, to which ∑OHPHE and 1-hydroxypyrene (1-OHPYR) might be the major contributors. In addition, gender and age modified the associations of ∑OHPHE and 1-OHPYR with inflammatory biomarkers, where girls and younger children were more susceptible. In conclusion, co-exposure to PAHs and PAEs was associated with elevated inflammation in children, in which ∑OHPHE and 1-OHPYR might play important roles.

Dynamic thiol disulfide homeostasis in painters as indices of oxidative stress

This study was designed to determine thiol-disulfide homeostasis as indices of oxidative stress in painters by using a novel and automated colorimetric measurement method. Male painters (n = 117) were separated into three groups according to duration of work; group 1 (<5 years), group 2 (5-14 years) and group 3 (≥15 years). Hippuric acid, trichloroacetic acid (TCA), and phenol in urine was determined. Catalase activity and ischemia-modified albumin (IMA) levels were also assessed. Disulfide/Native Thiol and Disulfide/Total Thiol of group 2 and group 3 were significantly higher than those of group 1 (p < 0.001). A positive correlation was observed between urinary phenol and disulfide/native thiol (r = 0.214, p = 0.035), IMA (r = 0.305, p = 0.002), disulfide (r = 0.209, p = 0.040), and duration of work (r = 0.341, p < 0.001). The newly developed automated colorimetric method used in our study proposes a promising, practical and daily applicable test for evaluating oxidative status of painters.

Selective detection of VOCs using microfluidic gas sensor with embedded cylindrical microfeatures coated with graphene oxide

Volatile organic compounds (VOCs) are major environmental pollutants. Exposure to VOCs has been associated with adverse health outcomes. The monitoring of hazardous VOCs is a vital step towards identifying their presence and preventing the risk of acute or chronic exposure and polluting the environment. One of the challenges associated with monitoring VOCs is selectivity of the sensor. Microfluidic gas sensors offer selective and sensitive detection capabilities that have been recently applied for detection of VOCs. In this study, we achieve improved selectivity for detection of a range of VOCs by adding micro- and nanofeatures to the microchannel of microfluidic gas sensors. First, microfeatures are embedded into the microchannel and their geometries are optimized using Taguchi design of experiment method. In the next step the microfeatures embedded microchannel is coated with graphene oxide, to increase the surface to volume ratio by introducing nanofeatures to the surfaces. The nano- and microfeatures are characterized by SEM, XPS, and water contact angle measurement. Finally, the changes in the sensor response are compared to plain microfluidic gas sensor, the results show an average of 64.4% and 120.9% improvement in the selectivity of the sensor with microfeatures and both nano- and microfeatures, respectively.

Repeated measurements of 21 urinary metabolites of volatile organic compounds and their associations with three selected oxidative stress biomarkers in 0-7-year-old healthy children from south and central China

Human beings are extensively and concurrently exposed to multiple volatile organic compounds (VOCs, including some Class I human carcinogens), which may induce oxidative stress in human body. Data on urinary metabolites of VOCs (mVOCs) among young children are limited. No studies have examined their inter-day variability of mVOCs and their associations with oxidative stress biomarkers (OSBs) using repeated urine samples from children. In this study, we measured twenty one mVOCs and three OSBs [8-hydroxy-2'-deoxyguanosine (8-OHdG; for DNA), 8-hydroxyguanosine (8-OHG; for RNA], and 4-hydroxy nonenal mercapturic acid (HNEMA; for lipid)] in 390 urine samples of 130 children (three samples on three consecutive days provided by each participant) aged 0-7 years from September 2018 to January 2019 in Shenzhen, south China, and Wuhan, central China. HPMMA (3-hydroxypropyl-1-methyl mercapturic acid/N-Acetyl-S-(3-hydroxypropyl-1-methyl)-l-cysteine), 3HPMA (3-hydroxypropyl mercapturic acid/N-Acetyl-S-(3-hydroxypropyl)-l-cysteine), and ATCA (2-aminothiazoline-4-carboxylic acid) had higher specific gravity-adjusted median concentrations (1 383, 286, and 273 μg/L, respectively) than the others. Intraclass correlation coefficients of mVOCs ranged from 0.29 to 0.71. After false-discovery rate (FDR, defined as FDR q-value < 0.05) adjustment, linear mixed-effects models revealed that 14 mVOCs were positively associated with 8-OHdG (β range: 0.09-0.37), 11 mVOCs were positively associated with 8-OHG (β range: 0.08-0.30), and 11 mVOCs were positively associated with HNEMA (β range: 0.21-0.70) in urine. Considering the weight of the mVOC index accounted for the associations, based on the weighted quantile sum regression model, parent compounds of DHBMA (3,4-dihydroxybutyl mercapturic acid/N-Acetyl-S-(3,4-dihydroxybutyl)-l-cysteine) and t,t-MA (trans,trans-muconic acid) should be listed as priority VOCs for management to mitigate health risks. For the first time, this study characterized the inter-day variability of urinary mVOCs and their associations with selected OSBs (8-OHdG, 8-OHG, and NHEMA) in young, healthy Chinese children.

The association between urinary metabolites of polycyclic aromatic hydrocarbons (PAHs) and cardiovascular diseases and blood pressure: a systematic review and meta-analysis of observational studies

Although epidemiological studies have discerned the association between polycyclic aromatic hydrocarbons (PAHs) exposure and hypertension and/or cardiovascular disease in the general population, the possible mechanisms for this association are not well understood. We sought to examine the association between urinary metabolites of PAHs and cardiovascular diseases (CVDs) and blood pressure in adults, by conducting a meta-analysis of observational studies. We searched PubMed, Scopus, Embase, and Web of science, up to July 2021, for observational studies that investigated the association between urinary metabolites of PAHs and CVDs and blood pressure in adults. Nine prospective studies, including 27,280 participants, were included. Based on overall pooled results, there was a significant positive association between all types of urinary metabolites of PAH and blood pressure (OR: 1.32; 95%, CI: 1.19 to 1.48, p < 0.0001) (I2 = 62.4%, p < 0.0001). There was no significant association between any urinary metabolite of PAH and CHD (OR: 0.93; 95%, CI: 0.83 to 1.03, p = 0.174) (I2 = 0%, p = 0.653). Overall, there was a significant positive association between all urinary metabolites of PAH and CVD (OR: 1.23; 95%, CI: 1.16 to 1.30, p < 0.0001) (I2 = 59.7%, p < 0.0001). The results of the present meta-analysis suggest that different metabolites PAHs are associated with an increased risk of CVD and HTN. Further studies, including randomized clinical trials, are needed to confirm the veracity of our findings.

8-Formylophiopogonanone B induces ROS-mediated apoptosis in nasopharyngeal carcinoma CNE-1 cells

Cancer is one of the leading causes of death in the world. It is very important to find drugs with high efficiency, low toxicity, and low side effects for the treatment of cancer. Flavonoids and their derivatives with broad biological functions have been recognized as anti-tumor chemicals. 8-Formylophiopogonanone B (8-FOB), a naturally existed homoisoflavonoids with rarely known biological functions, needs pharmacological evaluation. In order to explore the possible anti-tumor action of 8-FOB, we used six types of tumor cells to evaluate in vitro effects of this agent on cell viability and tested the effects on clone formation ability, scratching wound-healing, and apoptosis. In an attempt to elucidate the mechanism of pharmacological action, we examined 8-FOB-induced intracellular oxidative stress and -disrupted mitochondrial function. Results suggested that 8-FOB could suppress tumor cell viability, inhibit cell migration and invasion, induce apoptosis, and elicit intracellular ROS production. Among these six types of tumor cells, the nasopharyngeal carcinoma CNE-1 cells were the most sensitive cancer cells to 8-FOB treatment. Intracellular ROS production played a pivotal role in the anti-tumor action of 8-FOB. Our present study is the first to document that 8-FOB has anti-tumor activity in vitro and increases intracellular ROS production, which might be responsible for its anti-tumor action. The anti-tumor pharmacological effect of 8-FOB is worthy of further investigation.

Association among blood BPDE-DNA adduct, serum interleukin-8 (IL-8) and DNA strand breaks for children with pulmonary diseases

Exposure to benzo[a]pyrene (B[a]P) may be a risk factor for pulmonary diseases. To investigate the correlations among B[a]P exposure level, DNA strand breaks and pulmonary inflammation, we recruited 83 children diagnosed with pulmonary diseases and 63 healthy children from Guangzhou, China. Results showed that the levels of Benzo[a]pyrene diol epoxide (BPDE) DNA adduct in blood and IL-8 in serum in case group were significantly higher than those in control group (p < 0.01). Moreover, levels of atmospheric B[a]P in case group was about twice of those in control group, which was consistent with the levels of BPDE-DNA adduct in blood. Significant positive correlations were observed among the levels of BPDE-DNA adduct, IL-8 and DNA strand breaks (p < 0.05). Our findings indicate that environmental air is an important exposure source of B[a]P and higher B[a]P exposure may contribute to the occurrence of pulmonary inflammation and lead to high health risks.

Variability in urinary biomarkers of human exposure to polycyclic aromatic hydrocarbons and its association with oxidative stress

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants. Urinary concentrations of mono-hydroxylated metabolites of PAHs (OH-PAHs) have been used as biomarkers of these chemicals' exposure in humans. Little is known, however, with regard to intra- and inter-individual variability in OH-PAH concentrations and their association with oxidative stress. We conducted a longitudinal study of measurement of urinary concentrations of 15 OH-PAHs and 7 oxidative stress biomarkers (OSBs) of DNA damage [8-hydroxy-2'-deoxyguanosine (8-OHdG)], lipid [malondialdehyde (MDA) and F₂-isoprostanes (PGF_2α)] and protein [o,o'-dityrosine (diY)] peroxidation in 19 individuals for 44 consecutive days. Metabolites of naphthalene (OHNap), fluorene (OHFlu), phenanthrene (OHPhe), and pyrene (OHPyr) were found in >70% of 515 urine samples analyzed, at sum concentrations (∑OH-PAH) measured in the range of 0.46-60 ng/mL. After adjusting for creatinine, OHNap and ∑OH-PAH concentrations exhibited moderate predictability, with intra-class correlation coefficients (ICCs) ranging from 0.359 to 0.760. However, ICC values were low (0.001-0.494) for OHFlu, OHPhe, and OHPyr, which suggested poor predictability for these PAH metabolites. Linear mixed-effects analysis revealed that an unit increase in ∑OH-PAH concentration corresponded to 4.5%, 5.3%, 20%, and 21% increase in respective urinary 8-OHdG, MDA, PGF_2α, and diY concentrations, suggesting an association with oxidative damage to DNA, lipids, and proteins. The daily intakes of PAHs, calculated from urinary concentrations of OH-PAHs, were 10- to 100-fold below the current reference doses. This study provides valuable information to design sampling strategies in biomonitoring studies and in assigning exposure classifications of PAHs in epidemiologic studies.

Remediation of soils and sediments polluted with polycyclic aromatic hydrocarbons: To immobilize, mobilize, or degrade?

Polycyclic aromatic hydrocarbons (PAHs) are generated due to incomplete burning of organic substances. Use of fossil fuels is the primary anthropogenic cause of PAHs emission in natural settings. Although several PAH compounds exist in the natural environmental setting, only 16 of these compounds are considered priority pollutants. PAHs imposes several health impacts on humans and other living organisms due to their carcinogenic, mutagenic, or teratogenic properties. The specific characteristics of PAHs, such as their high hydrophobicity and low water solubility, influence their active adsorption onto soils and sediments, affecting their bioavailability and subsequent degradation. Therefore, this review first discusses various sources of PAHs, including source identification techniques, bioavailability, and interactions of PAHs with soils and sediments. Then this review addresses the remediation technologies adopted so far of PAHs in soils and sediments using immobilization techniques (capping, stabilization, dredging, and excavation), mobilization techniques (thermal desorption, washing, electrokinetics, and surfactant assisted), and biological degradation techniques. The pros and cons of each technology are discussed. A detailed systematic compilation of eco-friendly approaches used to degrade PAHs, such as phytoremediation, microbial remediation, and emerging hybrid or integrated technologies are reviewed along with case studies and provided prospects for future research.

Human exposure and health risk assessment of an increasingly used antibacterial alternative in personal care products: Chloroxylenol

The ban of some antibacterial ingredients, such as triclosan (TCS) and triclocarban (TCC), in personal care products (PCPs) in some countries (but not in China) has resulted in the increasing use of antibacterial alternatives, such as chloroxylenol (PCMX). However, the underlying human health risks and environmental impacts of PCMX exposure are largely unknown. Thus, the distribution characteristics of PCMX in PCPs and susceptible populations and the major routes and health risks of human exposure to PCMX were investigated. The PCMX, TCS, and TCC concentrations in PCPs, urine, drinking water, and surface water were determined using high-performance liquid chromatograph system equipped with diode array detector or triple quadrupole mass spectrometer. Results showed that PCMX is widely used in antibacterial hand sanitizers and household disinfectants in China. The addition of PCMX as an antibacterial ingredient in PCPs showed an increasing trend. The geomean concentrations of urinary PCMX in children and pregnant women were 21.6 and 31.9 μg·L^-1, respectively, which were much higher than TCS and TCC. A considerable concentration of PCMX ranging from 1.62 to 9.57 μg·L^-1 was observed in the aquatic environment, suggesting a potential massive-use of PCMX by humans. Human PCMX exposure via drinking was negligible because the PCMX concentrations in drinking water were less than 2.00 ng·L^-1. During human simulation experiment, we found that dermal contact was the dominant route of human PCMX exposure, accounting for 92.1% of the urinary PCMX concentration. The estimated daily intake of PCMX in 9.68% of children and 5.66% of pregnant women was higher than the reference dose. However, the urinary 8-hydroxy-2'-deoxyguanosine concentrations remained stable despite the elevated PCMX concentrations, thereby suggesting that daily PCMX exposure may not cause oxidative DNA damage in humans. Nevertheless, the potential ecotoxicity and health risks induced by chronic PCMX exposure cannot be ignored because of its increasing use.

Polycyclic aromatic hydrocarbon exposure, oxidative potential in dust, and their relationships to oxidative stress in human body: A case study in the indoor environment of Guangzhou, South China

A comparative study of internal and external exposure is a good method to comprehensively understand human exposure to environmental contaminants that may trigger oxidative stress in human body. Information is limited regarding the influences of reactive oxygen species (ROS) on human health from the environment. In addition, data on the contribution of polycyclic aromatic hydrocarbons (PAHs) from indoor environments, especially air, to total human exposure are still insufficient. The present study measured PAHs in paired indoor dust (n = 101), gas (polyurethane foams, n = 100), and particle samples (quartz fiber filters, n = 100) and their hydroxy metabolites (OH-PAHs) in 205 urine samples from 101 families in Guangzhou, South China. The oxidative potential (OP) in dust samples was quantified with a dithiothreitol (DTT) assay to reflect the oxidizability of ROSs, and explore the relationship between environmental ROSs and oxidative stress in humans (using urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) as a biomarker). The estimated daily intakes (EDIs) of Σ₁₆PAH via air inhalation were much higher than those from gas dermal contact, dust dermal contact, and dust ingestion (mean: 19.5 > 4.27 > 3.75 > 1.60 ng/kg_bw/day). Generally, approximately 16% of naphthalene, 28% of fluorene, 9% of phenanthrene, and 3% of pyrene were derived from indoor environments for all residents when compared with the total PAH exposure amount from all sources. Significantly positive relationships were found between OH-PAHs and 8-OHdG (coefficients β: 0.129-0.366, p < 0.05) checked by linear mixed effect models, and males seemed to be more susceptible than females to the DNA oxidative damage related to PAH exposure. The mean OP value in dust was 7.14 ± 6.68 pmol/(min·μg). Individual PAHs in dust gradually intensified the oxidizability of dust particles as their molecular weight increased. A potential but not significant dose-relationship was found between dusty OP and urinary 8-OHdG. Further work should determine the impact of chemical profiles on OP in different environmental media and continuously explore the potential to use OP as a useful indicator to reflect the total oxidizability of several groups of environmental pollutants.

Independent and combined associations of solid-fuel use and smoking with obesity among rural Chinese adults

Although solid-fuel use or smoking is associated with obesity measured by body mass index (BMI), research on their interactive effects on general and central obesity is limited. Data of 20,140 individuals in the Henan Rural Cohort Study was examined the independent and combined associations of solid-fuel use and smoking with prevalent obesity, which was measured by BMI, waist circumference (WC), waist-to-hip ratio (WHR), waist-to-height ratio (WHtR), body fat percentage (BFP), and visceral fat index (VFI). Multiple adjusted logistic regression models showed that the OR (95% CI) of prevalent obesity measured by BMI associated with exposure to solid fuels alone or with smoking was 0.78 (0.70, 0.86) or 0.46 (0.32, 0.66), compared with neither smoking nor solid-fuel exposure. Similar results had been found in other obese anthropometric indices and in the results of linear regression analysis. The results indicated that solid-fuel use and smoking have a synergistic effect on reduction in obesity indices. The effects of household air pollution from solid-fuel use and smoking on obesity should be considered when exploring the influencing factors of obesity.

Co-exposure to polycyclic aromatic hydrocarbons and phthalates and their associations with oxidative stress damage in school children from South China

Monohydroxylated polycyclic aromatic hydrocarbons (OH-PAHs), phthalate metabolites (mPAEs), and 8-hydroxy-2'-deoxyguanosine (8-OHdG) in the urine of school children aged 8-11 years from Shenzhen, China were measured in order to investigate oxidative stress damage from co-exposure to PAHs and PAEs. The concentrations of OH-PAHs and mPAEs in urine were 0.36-36.5 (median: 3.86) and 9.48-1609 (median: 240) ng/mL respectively. Gender and age did not influence urinary concentrations of ΣOH-PAHs and ΣmPAEs, but geographical variations (i.e., urban versus suburban) were observed. Levels of 8-OHdG were positively correlated with urinary OH-PAHs and mPAEs, with correlation coefficients (r) varying between 0.160 and 0.365 (p < 0.05). OH-PAHs made a greater contribution to oxidative DNA damage than mPAEs when these two types of pollutants were present at the same concentrations. Human health risks were assessed using the hazard quotient and the hazard index for the cumulative risk of a complex of chemicals. The results demonstrated that risks from PAHs could be neglected, but that 29.5 % of school children may be subject to obvious health risks from PAEs, especially diethylhexyl phthalate.

Biomonitoring of polycyclic aromatic hydrocarbons in the urine of lactating mothers: Urinary levels, association with lifestyle factors, and risk assessment

Polycyclic aromatic hydrocarbons (PAHs) are pollutants produced during incomplete combustion of organic matter and several industrial processes. Humans can be exposed to PAHs through ingestion of food, inhalation of tobacco smoke or polluted air, and dermal contact, causing immunologic, developmental, and reproductive problems. In the present research, eleven metabolites of PAHs were analyzed in the urine of 110 lactating women living in Spain (2015). PAH metabolites were extracted from the urine samples by liquid-liquid extraction and their determination was performed by liquid chromatography coupled to tandem mass spectrometry. In addition, information on lifestyle and dietary habits of the participants was collected using a questionnaire. All the PAH metabolites were detected in more than 70% of the samples, except for 3-hydroxybenzo(a)pyrene which was detected in less than 1% of the samples. The highest urinary levels were found for naphthalene metabolites, with geometric means of 0.8 (1-hydroxynaphthalene) and 7.1 ng ml^-1 (2-hydroxynaphthalene). The statistical analysis showed that smoking status, as well as the ingestion of certain food groups (vegetables, cereals, oils and fats, smoked fish and coffee), were the main influencing factors of exposure to PAHs. The estimated daily intake (EDI) was calculated for naphthalene, fluorene, phenanthrene, and pyrene, ranging from 6 to 1522 ng kg^-1·day^-1. The non-cancer risk associated to PAH exposure was estimated, showing hazard quotients (HQs) and hazard indexes (HIs) below 1. Therefore, it did not reveal a significant health risk for Spanish women due to PAH exposure.

Decreased levels of urinary di-2-ethylhexyl phthalate (DEHP) metabolites and biomarkers of oxidative stress in children exposed to DEHP-tainted foods in Taiwan in 2011: A 44-month follow-up

A major health scandal involving DEHP-tainted (di-2-ethylhexyl phthalate) foodstuffs occurred in Taiwan in 2011. We investigated temporal relationships between urinary DEHP metabolites and biomarkers of oxidative stress in two cohorts of potentially affected children during that food scandal. One cohort was collected from Kaohsiung Medical University Hospital in southern Taiwan between May and June of 2011 (the KMUH cohort). This cohort was followed up at 2, 6, and 44 months. The other cohort was collected from a nationwide health survey conducted by Taiwan's National Health Research Institutes (the NHRI cohort) for potentially affected people between August 2012 and January 2013. Both cohorts only included children 10 years old and younger who had provided enough urine for analysis of urinary DEHP oxidative metabolites and two markers of oxidative stress: 8-oxo-2'-deoxyguanosine (8-OHdG) and malondialdehyde (MDA). The KMUH cohort had a simultaneous and significant decrease in urinary DEHP metabolites, 8-OHdG, and MDA, with the lowest concentrations found at the 6-month follow up and maintained until the 44-month follow up, consistent with those from NHRI cohort at ∼15-18 months post-scandal (p > 0.05). There were decreases in both DEHP metabolites and oxidative stress markers across the populations, but no association was observed between DEHP metabolites and oxidative stress markers in individuals in the two cohorts. Continued follow-up is needed to determine long-term health consequences in these children.

New Approach to Dehydration of Xylose to 2-Furfuraldehyde Using a Mesoporous Niobium-Based Catalyst

Furfural chemistry is one of the most promising platforms directly derived from lignocellulose biomass. In this study, a niobium-based catalyst (mNb-bc) was synthesized by a new fast and simple method. This new method uses microemulsion to obtain a catalyst with a high specific surface area (340 m² g^-1), defined mesoporosity, and high acidity (65 μmol g^-1). Scanning electron microscopy revealed that mNb-bc has a rough surface. The mNb-bc was used to catalyze the conversion reaction of xylose into 2-furfuraldehyde in a monophasic system using water as a green solvent. This reaction was investigated using a 2³ experimental design by varying the temperature, time, and catalyst-to-xylose ratio (CXR). The responses evaluated were xylose conversion (X _c), reaction yield (Y), and selectivity to 2-furfuraldehyde (S). The optimized reaction conditions were used to evaluate the reaction kinetics. At milder reaction conditions of 140 °C, 2 h, and a CXR of 10%, mNb-bc led to an X _c value of 41.2%, an S value of 77.1%, and a Y value of 31.8%.

Exposure to heavy metals and its association with DNA oxidative damage in municipal waste incinerator workers in Shenzhen, China

Burning municipal waste produces a great deal of harmful heavy metals, which may lead to elevated exposure in incinerator workers and residents living nearby. However, relevant human exposure studies remain scarce, especially in China. This study aimed to determine the concentrations of ten heavy metals in urine of incinerator workers (n = 119, as the exposed group) and residents living nearby (n = 215, as the control group) from Shenzhen (China), and explore the associations between heavy metal exposure and DNA oxidative stress (indicated by 8-hydroxy-2'-deoxyguanosine or 8-OHdG) in humans. The median urinary concentrations of manganese (Mn), iron (Fe), chromium (Cr), arsenic (As), selenium (Se) and 8-OHdG in the exposed group were significantly higher than those in the control group (p < 0.05), suggesting occupational exposure elevated heavy metal intake for the incinerator workers. Nevertheless, there is no correlation statistically significant between the concentrations of any heavy metal and 8-OHdG in urine in the exposed group, indicating heavy metals releasing from waste incineration were not important factors to induce DNA oxidative stress. To our knowledge, this study firstly reported the concentrations of heavy metal in urine and their associations with DNA oxidative damage in waste incinerator workers in Shenzhen, China.

Non-linear relationships between seasonal exposure to polycyclic aromatic hydrocarbons and urinary 8-hydroxy-2'-deoxyguanosine levels among Chinese young students

Limited data are available on seasonal associations of polycyclic aromatic hydrocarbons (PAHs) exposure with oxidative DNA damage. We conducted a pilot study with 20 postgraduates, and measured urinary levels of mono-hydroxyl PAHs (OH-PAHs) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) for 7 consecutive days in the four seasons. We assessed the relationships of urinary OH-PAHs with urinary 8-OHdG in the whole year as well as cold- and warm-seasons. Summed OH-PAHs (∑OH-PAHs) were higher in cold season than in warm season. Each ln-unit (ln-transformed unit) increase in ∑OH-PAHs in the whole year corresponded to a 34%, 16% or 23% increase in urinary 8-OHdG levels at lag0, lag1 or lag2 day as well as a 26% increase in urinary 8-OHdG levels at lag0-2 days (cumulative effects). Each ln-unit increase in ∑OH-PAHs corresponded to a 36%, 26% or 46% increase in urinary 8-OHdG levels in cold season at lag0 day, lag1 day or lag2 day as well as a 36% increase in urinary 8-OHdG in warm season at lag0 day. Distributed non-linear cumulative lag models (DLNMs) indicated that each ln-unit increase in ∑OH-PAHs within the range of 5.7-8.1 nmol/mmol Cr had a stronger effect (coefficient β: 1.11-2.97 nmol/mmol Cr) on urinary 8-OHdG rather than non-cumulative DLNMs (coefficient β: 1.08-1.43 nmol/mmol Cr) as well as the non-linear dose-response relationships of ∑OH-PAHs with urinary 8-OHdG. PAHs exposure exhibited the lagged and cumulative effects on urinary 8-OHdG levels.

The association between urinary metabolites of polycyclic aromatic hydrocarbons and diabetes: A systematic review and meta-analysis study

To examine the association between urinary metabolites of polycyclic aromatic hydrocarbons (OH-PAHs) and diabetes, online databases, including PubMed, Scopus, and Web of Science, were searched on July 17, 2019. Of the 668 articles identified through searching, six cross-sectional studies involving 24,406 participants were included. The pooled odds ratio (OR) and 95% confidence interval (CI) were calculated using a random-effect model. Heterogeneity was measured by reporting the I-square index. Moreover, subgroup analysis according to types of metabolites was performed. We found a significantly higher odds of diabetes in the highest versus the lowest category of urinary naphthalene (NAP), fluorine (FLU), phenanthrene (PHEN), and total OH-PAH metabolites. The pooled OR (95% CI) was estimated at 1.47 (1.17, 1.78), 1.50 (1.29, 1.71), 1.41 (1.21, 1.60), and 1.61 (1.01, 2.21), respectively. We also found a significant association per 1-fold increase in FLU (OR = 1.09, 95% CI [1.00, 1.19]) and PHEN (OR = 1.19, 95% CI [1.08, 1.30]) metabolites. In subgroup analysis stratified by types of OH-PAH metabolites, A significant stronger odds of diabetes was observed in the highest versus the lowest category of 2-PHEN (OR = 1.66, 95% CI [1.32, 2.00]), 2-NAP (OR = 1.66, 95% CI [1.16, 2.17]), 2-FLU (OR = 1.62, 95% CI [1.28, 1.97]), and 9-FLU (OR = 1.62, 95% CI [1.21, 2.04]) metabolites. Furthermore, there was a meaningfully greater likelihood of diabetes per 1-fold increase in 2-FLU (OR = 1.34, 95% CI [1.10, 1.57]), 2-PHEN (OR = 1.33, 95% CI [1.14, 1.51]), and 3-PHEN (OR = 1.19, 95% CI [1.04, 1.34]) metabolites. In conclusion, our study suggests the significant odds of association between urinary OH-PAH metabolites and diabetes.

Urinary monohydroxylated polycyclic aromatic hydrocarbons in primiparas from Shenzhen, South China: Levels, risk factors, and oxidative stress

The main objectives of the present study were to investigate urinary monohydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) in 77 primiparas who live in Shenzhen, Guangdong Province, China, and their association with 8-hydroxy-2'-deoxyguanosine (8-OHdG) and human health risks. High detection frequencies of OH-PAHs demonstrated the wide occurrence of chemicals in the human exposure to PAHs. The urinary concentrations of Σ₇OH-PAHs ranged from 1.37 to 45.5 ng/mL, and the median concentrations of 1-hydroxynaphthalene (1-OHN), 2-hydroxynaphthalene (2-OHN), 2-hydoxyfluorene (2-OHF), ΣOHPhe (the sum of 1-, 2+ 3-hydroxyphenanthrene), and 1-hydroxypyrene (1-OHP) were 3.00, 2.58, 0.31, 0.44, and 0.51 ng/mL, respectively. In the sum concentration of seven OH-PAHs, 1-OHN accounted for the largest proportion (43.7% of Σ₇OH-PAHs), followed by 2-OHN (37.1%), 2-OHF (4.94%), 1-OHP (8.01%), 1-OHPhe (4.79%), and 2+3-OHPhe (1.46%). The present results showed that vehicle exhaust and petrochemical emission are the main sources of PAHs in primiparas in Shenzhen, and inhalation is the most important exposure route. The living conditions have a significant influence on human exposure to PAHs. The concentrations of 8-OHdG were positively correlated with OH-PAH concentrations in urine because evidence suggested that urinary 8-OHdG levels can be considered as a biomarker of oxidative DNA damage. Hazard quotient was used to assess the human health risks from exposure to single compound, and hazard index was used to assess the cumulative risks of the compounds, which demonstrated that the exposure risks from PAHs in primiparas were relatively low.

Associations between renal functions and exposure of arsenic and polycyclic aromatic hydrocarbon in adults living near a petrochemical complex

BACKGROUND

The understanding for the impact of petrochemical pollutants exposure on renal functions is limited.

OBJECTIVES

Our study examined the associations between renal functions and pollutants exposure in adult residents living in the vicinity of a petrochemical industry.

METHODS

We recruited 2069 adult residents near a big petrochemical complex in Taiwan in 2009-2012, and they were categorized into high exposure (HE) and low exposure (LE) groups based on their address to source by 10 km radius. Study subjects were measured the urinary levels of arsenic, cadmium, mercury, thallium, and 1-hydroxypyrene (1-OHP). The estimated glomerular filtration rate (eGFR) was calculated using the Taiwanese Chronic Kidney Disease Epidemiology Collaboration equation, and the chronic kidney disease (CKD) prevalence and risks were defined according to KDIGO 2012 guidelines. Adjusted generalized linear and logistic regression models were applied to evaluate the associations between petrochemical exposure and renal functions.

RESULTS

Subjects in the HE areas had significantly lower eGFR, higher CKD prevalence, and higher levels of urinary arsenic, cadmium, mercury, thallium and 1-OHP. The closer to complex and high exposure group of study subjects were significantly associated with the decrease in eGFR, higher ORs for CKD and high-intermediate risk of CKD. In addition, the study subjects who had two-fold urinary arsenic and 1-OHP levels were significantly with decreased 0.68 and 0.49 ml/min/1.73 m² of eGFR, respectively.

CONCLUSIONS

Residing closer and higher arsenic and polycyclic aromatic hydrocarbon exposure were associated with the renal impairment and risks of CKD among the residential population near the petrochemical industry.

Effect of exposure to phthalates on association of polycyclic aromatic hydrocarbons with 8-hydroxy-2'-deoxyguanosine

BACKGROUND

Although polycyclic aromatic hydrocarbons (PAHs) and phthalates separately related to oxidative DNA damage have been reported, the joint effect of them on oxidative DNA damage need to be evaluated.

METHODS

In this pilot study, 106 participants were recruited from the community-dwelling residents (n=1240) of Wuhan city, China. Each individual provided three continuous days of spot urine samples for measuring the urinary monohydroxylated PAHs (OH-PAHs), phthalates metabolites and 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels in the two seasons. Linear mixed effect model and Bayesian Kernel Machine Regression (BKMR) were used to analyze joint effect of urinary PAHs and phthalates metabolites on urinary 8-OHdG levels. We measured cellular and mitochondrial reactive oxygen species (ROS), malondialdehyde (MDA) and glutathione peroxidase (GSH-Px) levels as well as IL-6 and IL-8 secretions by the corresponding commercial kits in HepG2 cells treated with di (2-ethylhexyl) phthalate (DEHP, 62.5, 125.00, 250.00, 500.00 or 1000.00μM) alone, benzo[a]pyrene (BaP, 50.00μM) alone or both DEHP and BaP.

RESULTS

Linear mixed effect model showed that each of urinary PAHs metabolite was positively associated with urinary 8-OHdG levels; urinary level of mono (2-ethylhexyl) phthalate or monoisononyl phthalate was positively associated with urinary 8-OHdG levels; BKMR model indicated that a positive association of eight OH-PAHs with urinary 8-OHdG levels, nine urinary phthalates metabolites enhanced the association. We found that DEHP at the indicated concentration plus 50.00μM BaP increased cellular and mitochondrial ROS levels, IL-6 and IL-8 secretions at 24 and 48h as well as MDA levels and GSH-Px activities at 48h, compared to the solvent control.

CONCLUSIONS

Exposure to certain dose phthalates may attenuate the positive association of PAHs exposure with oxidative DNA damage in the body. DEHP at the certain concentrations enhanced BaP-induced mitochondrial ROS, pro-inflammatory response and the activation of the antioxidant defense system in HepG2 cells.

Assessment of the chemical hazard awareness of petrol tanker driver: A case study

Understanding the tanker driver hazard awareness on chemical exposure is important to ensure that they are fortified with the appropriate information regarding the risk of their occupation. This present study was conducted to determine the awareness of the petrol tanker driver on the chemical exposure during transportation petroleum product. The assessment on hazardous awareness of the petrol tank driver was conducted through questionnaire survey. Wherein, the questionnaire was designed with considering the variables of age of the driver, working experience, working hours in a day and knowledge on chemical hazard presence in the petroleum oil. A reliability test of Cronbach's Alpha was performed to validate the questionnaire and the Chi-Square test was conducted to determine the correlation among the studied variables. The findings of the present study revealed that the drivers who are frequently come into direct contact with petrol cannot identify the spillage had occurred during working. The study identified that there is an urgency to conduct training on safe handling of petroleum oil in order to eliminate the risk of chemical hazards exposure to the tanker driver.

Maternal urinary metabolites of PAHs and its association with adverse birth outcomes in an intensive e-waste recycling area

Polycyclic aromatic hydrocarbons (PAHs) are well-known carcinogenic and endocrine disrupting chemicals that have been concerned over the past few decades. We aimed to determine the hydroxylated PAH (OHPAH) metabolite concentrations in maternal urine collected from the e-waste-contaminated area of Guiyu and the reference area of Haojiang, China, and to evaluate their health effects on birth outcomes. The median ƩOHPAH concentration was 6.87 μg/g creatinine from Guiyu, and 3.90 μg/g creatinine from Haojiang. 2-OHNap and 1-OHPyr were the predominant metabolites. Residence in Guiyu and recycling in houses were associated with elevated 2-OHNap and 1-OHPyr. Standardized mean difference revealed that compared to low PAH metabolite levels in the first quartile, high PAH metabolite levels in the fourth quartile especially for 1-OHPyr, ƩOHPAHs and sometimes hydroxylphenanthrene compounds, presented a reduced size in birth outcomes (overall SMD: -0.09; 95% CI: -0.15, -0.03), including head circumference, BMI and Apgar 1 score, and increased size in height. After adjusting for confounders in regression models, an interquartile increase in ΣOHPAHs was associated with a decrease of 234.56 g in weight (95% CI: -452.00, -17.13), 1.72 cm in head circumference (95% CI: -2.96, -0.48), 1.06 kg/m² in BMI (95% CI: -1.82, -0.31) and 0.42 in Apgar 1 score (95% CI: -0.66, -0.18), respectively. These findings suggest high exposure to PAHs during pregnancy in e-waste areas, posing a potential threat to neonatal development, which likely can be attributed to direct e-waste recycling activities. Ongoing studies should be continued to monitor human exposure and health, in particular for vulnerable individuals in e-waste-polluted areas.

Cardiometabolic traits mediated the relationship from urinary polycyclic aromatic hydrocarbons metabolites to heart rate variability reduction: A community-based study

Polycyclic Aromatic Hydrocarbons (PAHs) exposure was related with metabolic syndrome (MetS) and heart rate variability (HRV) reduction, and HRV was also affected by cardiometabolic traits. However, the role of cardiometabolic traits in the associations from PAHs exposures to HRV was largely unknown. We conducted this study to investigate whether the relationship between PAHs exposure and HRV reduction was mediated by cardiometabolic traits. Levels of urinary polycyclic aromatic hydrocarbons metabolites (OH-PAHs), 10min-HRV, and metabolic traits were accurately measured for 2476 participants from Wuhan-Zhuhai (WHZH) cohort. Single mediator and multiple mediator models were used to evaluate the mediation effects of cadiometabolic traits. The concentrations of ΣOH-PAHs ranged from 4.20 to 8.63 mg/mmol Cr. When compared with the lowest tertile, ΣOH-PAHs in the highest tertile were significantly related with 20% (95% confidence interval [95%CI]:1%, 40%), 35% (95%CI: 14%, 56%), 22% (95%CI: 1%, 44%), and 38% (95%CI: 9%, 68%) decreases in very low frequency (VLF), low frequency (LF), high frequency (HF), and total power (TP) for participants with MetS, respectively. No statistically significant associations between ΣOH-PAHs and HRV indices were observed for participants without MetS. Similar results were found when we investigated the relationships between OH-PAHs and HRV indices by three groups of OH-PAHs (including total hydroxynaphthalene [ΣOHNa], total hydroxy fluorene [ΣOHFlu], and total hydroxyphenanthrene [ΣOHPh] metabolites). Further, mediation analysis suggested that cardiometabolic traits, including fasting glucose (GLU), high density lipoprotein (HDL), and blood pressure partially mediated the relationship from ΣOH-PAHs to HRV reduction. GLU was the strongest mediator, with mediation percentages of 15.70% for VLF, 14.70% for LF, 43.03% for HF, and 5.61% for TP. Our study found that the relationships between OH-PAHs and HRV reduction differed among participants with and without MetS, and these relationships were found to be partially mediated by cardiometabolic traits, especially fasting glucose. Further studies are encouraged to validate our findings and investigate potential mechanisms.

Investigating the association between urinary levels of acrylonitrile metabolite N-acetyl-S-(2-cyanoethyl)-L-cysteine and the oxidative stress product 8-hydroxydeoxyguanosine in adolescents and young adults

Acrylonitrile is a colorless volatile liquid mostly present in tobacco smoke. Acrylonitrile exposure has shown to increase oxidative stress in animal studies; however, there was no previous research in human epidemiology. In this study, 853 subjects were recruited from a cohort of Taiwanese adolescents and young adults to investigate the association between urinary concentrations of the acrylonitrile metabolite N-acetyl-S-(2-cyanoethyl)-L-cysteine (CEMA), the oxidative stress product 8-hydroxydeoxyguanosine (8-OHdG) and cardiovascular disease (CVD) risk factors. The geometric mean (SD) of CEMA and 8-OHdG concentrations were 4.67 (8.61) μg/L and 2.97 (2.14) μg/L, respectively. 10% elevated in CEMA (μg/L) was positively correlated with the change of 8-OHdG levels (μg/L) (β = 0.325, SE = 0.105, P = 0.002) in multiple linear regression analyses. The urinary CEMA was not related to other CVD risk factors. In subpopulation analyses, the association between CEMA and 8-OHdG was evident in all genders, adolescents, homeostasis model assessment of insulin resistance score ≥0.89, and environmental tobacco smokers. In this study, we observed that higher levels of CEMA levels were correlated with increased levels of 8-OHdG in this cohort. Future research on exposure to acrylonitrile and oxidative stress was warranted.

Volatile Organic Compounds in Air: Sources, Distribution, Exposure and Associated Illnesses in Children

BACKGROUND

Toxic volatile organic compounds (VOC), like benzene, toluene, ethylbenzene and xylenes (BTEX), are atmospheric pollutants representing a threat to human health. They are released into the environment from mobile sources in urban settings, but newly polluted areas are gaining importance in countries where accelerated industrialization is taking place in suburban or rural settings.

METHODS

The review includes studies done in Mexico and Latin-America and countries considered to have emerging economies and are compared with similar studies in developed countries. Data about environmental VOC levels and exposure of children have been included. Also, information about health effects was reviewed. Articles were searched in PubMed and Scopus, and information was also obtained from the United States Environmental Protection Agency (EPA), the EPAs Integrated Risk Information System (IRIS-EPA) and state reports on air quality of Mexican cities.

RESULTS

VOC or BTEX levels reported in industrial and suburban areas were found to be higher due to the burning of fossil fuels and waste emission; whereas, in big cities, VOC emissions were mainly due to mobile sources. Even though TEX levels were under reference values, benzene was found at levels several times over this value in cities and even higher in industrial zones. Elevated VOC emissions were also reported in cities with industrial development in their peripheral rural areas.Public health relevance: Industrial activities have changed the way of life of small towns, which previously had no concern about environmental pollution and chemicals. No air monitoring is done in these places where toxic chemicals are released into rivers and the atmosphere. This work demonstrates the need for environmental monitors to protect human life in suburban and rural areas where industrial growth occurs without planning and ecological or health protection, compromising the health of new generations beginning in fetal development.

Urinary polycyclic aromatic hydrocarbon metabolites among 3-year-old children from Krakow, Poland

Polycyclic aromatic hydrocarbons (PAHs) are widespread in the environment and can adversely affect human health. The aim of the present study is to describe the level of PAHs exposure in children living in Kraków, one of the most polluted cities in Poland, and to determine the relationship of urinary biomarkers with environmental PAHsexposure. Urinary monohydroxy metabolites (OH-PAHs) of 20 PAHs were assessed in 218 three-year old children, of which only 10 were present in nearly all the samples: monohydroxy metabolites of naphthalene, fluorene, phenantrene and pyrene. Of the metabolites analyzed, hydroxynaphthalenes were predominant and constituted almost 73% of total excreted OH-PAHs, while 1-OH-PYRene was the least abundant (2.3% of total OH-PAHs). All measured urinary OH-PAHs were statistically significantly correlated with each other (R = 0.165-0.880) but the highest correlation coefficients with other individual OH-PAHs and with total OH-PAHs were observed for 2-OH-FLUOR. Children exposed at home to environmental tobacco smoke (ETS) had higher concentrations of fluorene and pyrene urinary metabolites compared to those without ETS exposure; and those exposed to gas-based appliances used for cooking or heating water had higher levels of fluorene and phenanthrene metabolites than children not exposed. The use of coal, wood or oil for heating was associated with elevated levels of 1-OH-PYRene. Urinary PAHs metabolites only modestly reflect high molecular weight carcinogenic PAHs exposures such as those monitored in air in the present study. None of the measured PAHs metabolites was correlated with airborne PM_2.5 and only two were slightly correlated with measured higher molecular mass airborne PAHs. The average concentrations of these specific metabolites in Polish children were much higher than observed in other pediatric populations living in developed countries. Our findings suggest that to capture various sources of PAHs, in addition to 1-OH-PYRene, biomonitoring of PAHs exposure should include 2-OH-NAP and 2-OH-FLUOR.

Ambient Nonmethane Hydrocarbon Levels Along Colorado's Northern Front Range: Acute and Chronic Health Risks

Oil and gas (O&G) facilities emit air pollutants that are potentially a major health risk for nearby populations. We characterized prenatal through adult health risks for acute (1 h) and chronic (30 year) residential inhalation exposure scenarios to nonmethane hydrocarbons (NMHCs) for these populations. We used ambient air sample results to estimate and compare risks for four residential scenarios. We found that air pollutant concentrations increased with proximity to an O&G facility, as did health risks. Acute hazard indices for neurological (18), hematological (15), and developmental (15) health effects indicate that populations living within 152 m of an O&G facility could experience these health effects from inhalation exposures to benzene and alkanes. Lifetime excess cancer risks exceeded 1 in a million for all scenarios. The cancer risk estimate of 8.3 per 10 000 for populations living within 152 m of an O&G facility exceeded the United States Environmental Protection Agency's 1 in 10 000 upper threshold. These findings indicate that state and federal regulatory policies may not be protective of health for populations residing near O&G facilities. Health risk assessment results can be used for informing policies and studies aimed at reducing and understanding health effects associated with air pollutants emitted from O&G facilities.

The Effect of Nitric Oxide Pollution on Oxidative Stress in Pregnant Women Living in Durban, South Africa

The purpose of the study was to evaluate the effect nitric oxide (NO _x ) pollution had on maternal serum 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-OHdG) levels and neonatal outcomes in pregnant women living in Durban, South Africa (SA). Women, in their third trimester with singleton pregnancies, were recruited from the heavily industrialised south (n = 225) and less industrialised north (n = 152). Biomarker levels of serum 8-OHdG concentrations were analysed, and the women were genotyped for glutathione-S-transferases pi 1 (GSTP1) and glutathione-S-transferases mu 1 (GSTM1) polymorphisms. The level of NO _x pollution in the two regions was determined by using land use regression modelling. The serum 8-OHdG was shown to correlate significantly with NO _x levels; this relationship was strengthened in the south (p < 0.05). This relationship was still observed after adjusting for maternal characteristics. GSTP1 was significantly associated with the south region, where the variant (AG+GG) genotype was associated with increased 8-OHdG levels as a result of NO _x exposure (p < 0.05). GSTM1 null genotype was associated with a positive correlation between NO _x and 8-OHdG levels (p < 0.05). NO _x levels were found marginally to reduce gestational age (p < 0.05) with mothers carrying male neonates. Variant GSTP1 and living in the north were factors that contributed to gestational age reduction (p < 0.05). Our study demonstrated that NO _x exposure resulted in increased 8-OHdG levels in pregnant women living in Durban, SA, which led to gestational age reduction. The GSTP1 variant increased susceptibility of individuals to harmful effects of NO _x .

Is there any association between urinary metabolites of polycyclic aromatic hydrocarbons and thyroid hormone levels in children and adolescents?

Considering the possible effects of polycyclic aromatic hydrocarbons (PAHs) on thyroid function, the current study aims to investigate the association of PAH urinary metabolites with the level of thyroid hormones in a sample of Iranian children and adolescents. This cross-sectional study was conducted from September 2015 to July 2016 in Isfahan, Iran. Participants were 150 students, aged 6-18 years, who were selected by multistage cluster random sampling from schools of Isfahan province. Blood and urine samples of participants were obtained for measurement of thyroid hormone levels (measured by immunoradiometric assay) and PAH urinary metabolites, including 1-hydroxynaphthalene, 2-hydroxynaphthalene, 9-hydroxyphenanthrene, and 1-hydroxypyrene. The association of serum thyroid-stimulating hormone (TSH) and PAH urinary metabolites was determined by correlation and regression analyses. Multivariate regression analysis revealed significant association between serum TSH and PAH urinary metabolites; this association remained significant after adjustment for gender and age. The corresponding figures were r = 0.85 for 1-naphthol, r = 0.86 for 2-naphthol, r = 0.87 for 1-hydroxypyrene, and r = 0.42 for 9-phenantrol, respectively, all p values < 0.001. The mean levels of 1-hydroxypyrene and 9-phenanthrol were higher in boys than those in girls (p < 0.05). The findings of this study indicated significant positive association between urinary PAH biomarkers and the TSH level in children and adolescents. It can be suggested that long-term exposure to PAHs might result in thyroid function impairment. The clinical implication of the current findings should be confirmed by future longitudinal studies.

Formation of Developmentally Toxic Phenanthrene Metabolite Mixtures by Mycobacterium sp. ELW1

Mycobacterium sp. ELW1 co-metabolically degraded up to 1.8 μmol of phenanthrene (PHE) in ∼48 h, and hydroxyphenanthrene (OHPHE) metabolites, including 1-hydroxyphenanthrene (1-OHPHE), 3-hydroxyphenanthrene (3-OHPHE), 4-hydroxyphenanthrene (4-OHPHE), 9-hydroxyphenanthrene (9-OHPHE), 9,10-dihydroxyphenanthrene (1,9-OHPHE), and trans-9,10-dihydroxy-9,10-dihydrophenanthrene (trans-9,10-OHPHE), were identified and quantified over time. The monooxygenase responsible for co-metabolic transformation of PHE was inhibited by 1-octyne. First-order PHE transformation rates, kPHE, and half-lives, t1/2, for PHE-exposed cells were 0.16-0.51 h-1 and 1.4-4.3 h, respectively, and the 1-octyne controls ranged from 0.015-0.10 h-1 to 7.0-47 h, respectively. While single compound standards of PHE and trans-9,10-OHPHE, the major OHPHE metabolite formed by ELW1, were not toxic to embryonic zebrafish (Danio rerio), single compound standards of minor OHPHE metabolites, 1-OHPHE, 3-OHPHE, 4-OHPHE, 9-OHPHE, and 1,9-OHPHE, were toxic, with effective concentrations (EC50's) ranging from 0.5 to 5.5 μM. The metabolite mixtures formed by ELW1, and the reconstructed standard mixtures of the identified OHPHE metabolites, elicited a toxic response in zebrafish for the same three time points. EC50s for the metabolite mixtures formed by ELW1 were lower (more toxic) than those for the reconstructed standard mixtures of the identified OHPHE metabolites. Ten unidentified hydroxy PHE metabolites were measured in the derivatized mixtures formed by ELW1 and may explain the increased toxicity of the ELW1 metabolites mixture relative to the reconstructed standard mixtures of the identified OHPHE metabolites.

Exposure to polycyclic aromatic hydrocarbons and volatile organic compounds among recently pregnant rural Guatemalan women cooking and heating with solid fuels

BACKGROUND

Household air pollution is a major contributor to death and disability worldwide. Over 95% of rural Guatemalan households use woodstoves for cooking or heating. Woodsmoke contains carcinogenic or fetotoxic polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs). Increased PAHs and VOCs have been shown to increase levels of oxidative stress.

OBJECTIVE

We examined PAH and VOC exposures among recently pregnant rural Guatemalan women exposed to woodsmoke and compared exposures to levels seen occupationally or among smokers.

METHODS

Urine was collected from 23 women who were 3 months post-partum three times over 72h: morning (fasting), after lunch, and following dinner or use of wood-fired traditional sauna baths (samples=68). Creatinine-adjusted urinary concentrations of metabolites of four PAHs and eight VOCs were analyzed by liquid chromatography-mass spectrometry. Creatinine-adjusted urinary biomarkers of oxidative stress, 8-isoprostane and 8-OHdG, were analyzed using enzyme-linked immunosorbent assays (ELISA). Long-term (pregnancy through 3 months prenatal) exposure to particulate matter and airborne PAHs were measured.

RESULTS

Women using wood-fueled chimney stoves are exposed to high levels of particulate matter (median 48h PM2.5 105.7μg/m3; inter-quartile range (IQR): 77.6-130.4). Urinary PAH and VOC metabolites were significantly associated with woodsmoke exposures: 2-naphthol (median (IQR) in ng/mg creatinine: 295.9 (74.4-430.9) after sauna versus 23.9 (17.1-49.5) fasting; and acrolein: 571.7 (429.3-1040.7) after sauna versus 268.0 (178.3-398.6) fasting. Urinary PAH (total PAH: ρ=0.89, p<0.001) and VOC metabolites of benzene (ρ=0.80, p<0.001) and acrylonitrile (ρ=0.59, p<0.05) were strongly correlated with long-term exposure to particulate matter. However urinary biomarkers of oxidative stress were not correlated with particulate matter (ρ=0.01 to 0.05, p>0.85) or PAH and VOC biomarkers (ρ=-0.20 to 0.38, p>0.07). Urinary metabolite concentrations were significantly greater than those of heavy smokers (mean cigarettes/day=18) across all PAHs. In 15 (65%) women, maximum 1-hydroxypyrene concentrations exceeded the occupational exposure limit of coke-oven workers.

CONCLUSIONS

The high concentrations of urinary PAH and VOC metabolites among recently pregnant women is alarming given the detrimental fetal and neonatal effects of prenatal PAH exposure. As most women used chimney woodstoves, cleaner fuels are critically needed to reduce smoke exposure.

8-Hydroxydeoxyguanosine as a biomarker of oxidative DNA damage in workers exposed to low-dose benzene

•

Gasoline station attendants have higher urinary t,t,-MA and 8-OHdG levels.

•

There is strong correlation between 8-OHdG and benzene exposure level.

•

8-OHdG levels are significantly correlated also with job seniority.

•

Low-level chronic exposure to benzene can determine oxidative damage on DNA.

The present study aims to investigate the relation between exposure to low-dose benzene and the occurrence of oxidative DNA damage in gasoline station workers, as well as the possible role of interfering or confounding factors.

Urine levels of 8-OHdG were evaluated by a competitive immunoassay in a group of 80 men, employed in gasoline stations located in East Sicily and compared with a control group (n = 63) of male office employees not occupationally exposed to benzene. Information regarding socio-demographic characteristics, lifestyle and job-related records were provided through a questionnaire.

Significantly higher (p < 0.05) urinary t,t,-MA and 8-OHdG levels were observed in gasoline station attendants compared to subjects not exposed to benzene.

Pearson’s test demonstrated a strong correlation (r = 0.377, p < 0.001) between 8-OHdG and benzene exposure level. 8-OHdG significantly correlated also with job seniority, (r = 0.312, p < 0.01), whereas the relation with age resulted weaker (r = 0.242, p < 0.05). Multiple linear regression analysis, performed to exclude a role for confounding factors, showed that variables like gender, smoking habit, alcohol consumption and BMI did not have a significant influence on the measured biomarkers. No subject enrolled in the study presented signs or symptoms of work-related disease or other illness linked to oxidative stress.

These results suggest that low-level chronic exposure to benzene among gasoline station attendants can determine oxidative damage on DNA, as indicated by alteration of 8-OHdG which may represent a non-invasive biomarker of early genotoxic damage in exposed subjects.

Dose-response relationship between urinary polycyclic aromatic hydrocarbons metabolites and urinary 8-hydroxy-2'-deoxyguanosine in a Chinese general population

Association of exposure to polycyclic aromatic hydrocarbons (PAHs) with increased urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) formation has been reported in occupational population and children. However, studies on the association between them in general population are limited. A total of 1864 eligible subjects from the baseline Wuhan participants of the Wuhan-Zhuhai Cohort Study (n = 3053) were included in this study, after excluding individuals with certain disease and missing data on urinary monohydroxy PAHs (OH-PAHs) and 8-OHdG levels. Urinary monohydroxy PAHs and 8-OHdG levels were measured by gas chromatography-mass spectrometry and high performance liquid chromatography-electrochemical detection, respectively. Association of urinary OH-PAHs with urinary 8-OHdG was analyzed by multiple linear regression analysis. We found a dose-dependent relationship between urinary PAHs metabolites and urinary 8-OHdG (p < 0.05 for all). Furthermore, more evidence for the association of total concentrations of urinary OH-PAHs with 8-OHdG levels were observed in individuals with normal body mass index or central obesity (p < 0.01 for all). There was a dose-dependent relationship between urinary OH-PAHs levels and urinary 8-OHdG levels among a general Chinese population. Exposure to background PAHs may have a greater influence on urinary 8-OHdG levels in individuals with central obesity.

Emerging trends in photodegradation of petrochemical wastes: a review

Various human activities like mining and extraction of mineral oils have been used for the modernization of society and well-beings. However, the by-products such as petrochemical wastes generated from such industries are carcinogenic and toxic, which had increased environmental pollution and risks to human health several folds. Various methods such as physical, chemical and biological methods have been used to degrade these pollutants from wastewater. Advance oxidation processes (AOPs) are evolving techniques for efficient sequestration of chemically stable and less biodegradable organic pollutants. In the present review, photocatalytic degradation of petrochemical wastes containing monoaromatic and poly-aromatic hydrocarbons has been studied using various heterogeneous photocatalysts (such as TiO₂, ZnO and CdS. The present article seeks to offer a scientific and technical overview of the current trend in the use of the photocatalyst for remediation and degradation of petrochemical waste depending upon the recent advances in photodegradation of petrochemical research using bibliometric analysis. We further outlined the effect of various heterogeneous catalysts and their ecotoxicity, various degradation pathways of petrochemical wastes, the key regulatory parameters and the reactors used. A critical analysis of the available literature revealed that TiO₂ is widely reported in the degradation processes along with other semiconductors/nanomaterials in visible and UV light irradiation. Further, various degradation studies have been carried out at laboratory scale in the presence of UV light. However, further elaborative research is needed for successful application of the laboratory scale techniques to pilot-scale operation and to develop environmental friendly catalysts which support the sustainable treatment technology with the "zero concept" of industrial wastewater. Nevertheless, there is a need to develop more effective methods which consume less energy and are more efficient in pilot scale for the demineralization of pollutant.

The relationship between plasma and urinary 8-hydroxy-2-deoxyguanosine biomarkers measured by liquid chromatography tandem mass spectrometry

Although 8-hydroxy-2-deoxyguanosine (8-OHdG) is a widely used promising biomarker of DNA damage, there are concerns about which tissues or body fluids should be sampled. The objective of this study is to evaluate the correlation of DNA oxidative damage biomarkers, 8-OHdG, between blood and urine and risk factors associated with 8OHdG. The study population was recruited from a baseline survey of a worksite lifestyle study including 92 office workers aged 23 to 60 years. A self-administered questionnaire was used to collect information on personal characteristics. The plasma and urinary 8-OHdG was measured by liquid chromatography tandem mass spectrometry (LC-MS/MS). In linear regression, a positive relation was found (p < 0.01) between the log-transformed plasma and urinary 8-OHdG levels adjusted for gender, age, BMI, and smoking status. Our findings showed that age, gender and smoking were significantly associated with plasma 8-OHdG, but not with urinary 8-OHdG. Our results suggest that there is a positive relation between the biomarkers of plasma (steady state DNA damage) and urinary 8-OHdG (total DNA damage). However, the plasma 8-OHdG is more sensitive than urinary 8-OHdG to detect increased oxidative damages induced by risk factors.

Trace elements are associated with urinary 8-hydroxy-2'-deoxyguanosine level: a case study of college students in Guangzhou, China

Many trace heavy elements are carcinogenic and increase the incidence of cancer. However, a comprehensive study of the correlation between multiple trace elements and DNA oxidative damage is still lacking. The aim of this study is to investigate the relationships between the body burden of multiple trace elements and DNA oxidative stress in college students in Guangzhou, China. Seventeen trace elements in urine samples were determined by inductively coupled plasma-mass spectrometry (ICP-MS). Urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG), a biomarker of DNA oxidative stress, was also measured using liquid chromatography tandem mass spectrometer (LC-MS/MS). The concentrations of six essential elements including manganese (Mn), copper (Cu), nickel (Ni), selenium (Se), strontium (Sr), and molybdenum (Mo), and five non-essential elements including arsenic (As), cadmium (Cd), aluminum (Al), stibium (Sb), and thallium (Tl), were found to be significantly correlated with urinary 8-OHdG levels. Moreover, urinary levels of Ni, Se, Mo, As, Sr, and Tl were strongly significantly correlated with 8-OHdG (P < 0.01) concentration. Environmental exposure and dietary intake of these trace elements may play important roles in DNA oxidative damage in the population of Guangzhou, China.

STAT3 methylation in white blood cells as a novel sensitive biomarker for the toxic effect of low-dose benzene exposure

Alterations in DNA methylation patterns play an essential role in disease process and are associated with cancer risk. To explore the toxic effect and early sensitive biomarker of the health effects of low-dose benzene exposure (LDBE), and investigate the correlation between DNA methylation and the toxic effect of LDBE, a cross-sectional study was conducted in a sample of 571 workers; 312 workers who were exposed to a 1.82 ± 1.16 mg m-3 air benzene concentration were assigned to the LDBE group, while 259 non-known benzene exposure (NBE) workers were assigned to the control group, with an air benzene concentration of 0.06 ± 0.01 mg m-3. Routine blood indexes, alanine transaminase (ALT), oxidative stress parameters and signal transducer and activator of transcription 3 (STAT3) methylation were detected. Compared with the NBE population, the STAT3 methylation level (P = 0.001), Platelets (PLTs) (P = 0.002) and 8-isoprostane-PGFs (8-iso-PGF2a) (P = 0.001) manifested a significant reduction, while ALT (P = 0.002) and 8-hydroxy-2 deoxyguanosine (8-OHdG) (P = 0.002) showed a significant rise in the LDBE population. In addition, a significant correlation was observed between STAT3 methylation and oxidative stress, namely 8-OhdG and 8-iso-PGF2a. Furthermore, a multivariate analysis showed that the STAT3 methylation (structure loadings = 0.909) was the most strongly correlated with the other set of variables, especially with white blood cells (WBCs) (structure loadings = 0.675). Taken together, STAT3 methylation may be the underlying mechanism involved in the early toxic effect of LDBE, therefore, STAT3 methylation can be a novel sensitive biomarker for the toxic effect of low-dose benzene exposure.

Regression models to estimate the total concentration of polycyclic aromatic hydrocarbon metabolites in urine

Polycyclic aromatic hydrocarbons (PAH) are potentially mutagenic and carcinogenic and as such their exposure is of serious concern. Regression models to estimate the total concentration of polycyclic aromatic hydrocarbon metabolites (∑PAH) in urine were developed. Using data from National Health and Nutrition Examination Survey for the years 2003-2008 and 2011-2012, regression models were developed to estimate ∑PAH in urine. The performance of the fitted models were computed by comparing percent predicted values located between 0 and 5%, 5-10%, 15-20% and >20% of the observed values. While data for 2003-2008 were used to fit the regression models, the data for 2011-2012 were solely used to evaluate the performance of the fitted models. R(2) of the fitted model was 94.7%. About 46% of the predicted values for the 2003-2008 data and over 48% of the predicted values for the 2011-2012 data were found to be between 0 and 10% of the observed values. In order to use these models, in addition to age, gender, and smoking status, and optionally race/ethnicity, the knowledge of the levels of only 1-hydroxynaphthalene, 2-hydroxynaphthalene, and 9-hydroxyfluorene is necessary. Models that optionally require the knowledge of the levels of urine creatinine were also developed.