Characteristics and potential health risk of rural Tibetans' exposure to polycyclic aromatic hydrocarbons during summer period

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.

Association of occupational exposure to polycyclic aromatic hydrocarbons in workers with hypertension from a northeastern Chinese petrochemical industrial area

Elevated urinary polycyclic aromatic hydrocarbon metabolites have been linked to an increased risk of cardiovascular diseases (CVDs). However, for petrochemical workers with potentially high PAH exposure, it remains largely unknown whether the link will be amplified. Thus, this work aimed to investigate 14 urinary mono-hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) in 746 petrochemical workers working in a Chinese petrochemical industrial area and their association with the risk of hypertension using the binary logistic regression. Metabolites of naphthalene, fluorene, phenanthrene, and pyrene were frequently detected in the 746 urine samples analyzed (>98%), with Σ₁₀OH-PAH concentration in the range of 0.906-358 ng/mL. 2-hydroxynaphthalene accounted for the largest proportion of ten detected OH-PAHs (60.8% of Σ₁₀OH-PAHs). There were significant correlations between these metabolites and other factors, including gender, age, and body mass index. Diastolic blood pressure, not systolic blood pressure, was significant positively associated with the urinary Σ₁₀OH-PAH concentrations of the petrochemical workers. Elevated urinary 2/3-OH-Flu was significantly associated with an increased risk of hypertension (adjusted odds ratio: 1.96, 95% confidence interval: 1.20-3.18, p = 0.007), suggesting that PAH exposure in petrochemical workers was a driving factor of hypertension. In the stratified analysis, the association was more pronounced in those who were overweight with older age. Although the PAH exposure risk in petrochemical workers based on the estimated daily intakes was relatively low. Given the long-term impact, we call attention to CVDs of petrochemical workers.

Levels, distribution, sources and children health risk of PAHs in residential dust: A multi-city study in China

BACKGROUND

Polycyclic aromatic hydrocarbons (PAHs) are typical residential pollutants mainly from biofuel combustion that impose inevitable risk to children. The PAHs in residential dust is universal in most Chinese households with an obvious public health concern.

METHODS

In this observational study, a total of 235 residential dust samples from 8 Chinese cities (Panjin, Shijiazhuang, Lanzhou, Luoyang, Xi'an, Wuxi, Mianyang, and Shenzhen) were collected from April 2018 to March 2019, which were extracted and analyzed for 16 priority PAHs by HPLC/FD-UV. Diagnostic ratios, hierarchical clustering analysis and principal component analysis were applied simultaneously for source apportionments. Incremental lifetime cancer risk was employed to estimate children's health risks based on the assumed exposure scenarios. Spearman correlation, Mann-Whitney U test, Kruskal-Wallis H test and Partial Least Squares were used to screen the factors affecting the concentration of PAHs in residential dust.

RESULTS

The median concentration of ∑₁₆PAHs in residential dust from 8 cities was 44.11 μg/g (0.04 - 355.79 μg/g). ∑₁₆PAHs were found both higher in dust samples in heating season and from downwind households only in Mianyang (p < 0.05). The leading two sources of PAHs were combustion processes and automobile exhaust emissions based on four principal components that accounted for 74.29 % of the total variance. Indoor air environmental factors, household characteristics, and residents' behavioral lifestyles may be the influencing factors of residential dust PAHs. The carcinogenic risk of children aged 0 - 5 years, under the moderate exposure level of PAHs in residential dust, exceeded the acceptable level (10^-5 - 10^-4 for dermal contact and 10^-6 - 10^-5 for ingestion).

CONCLUSIONS

There was serious PAHs pollution in residential dust under actual living conditions in eight cities across China. More evidence-based measures were needed to control PAHs pollution to safeguard children's health according to appointed sources and influencing factors in residential dust.

Contributors to reductions of PM2.5-bound heavy metal concentrations and health risks in a Chinese megacity during 2013, 2016 and 2019: An advanced method to quantify source-specific risks from various directions

PM_2.5-bound heavy metals were measured in a Chinese megacity (Tianjin) in 2013, 2016 and 2019, and analyzed by a new RSDA method (source directional apportionment of risks). Through combining the receptor model, cluster analysis of back trajectories, and risk assessment, the RSDA was developed in this work to quantify source-specific risks from each direction. Concentrations of PM_2.5 and most species (especially for heavy metals) underwent various reductions, and the incremental lifetime cancer risk (ILCR) and non-cancer risk (HQ) declined by more than 80% from 2013 to 2019. Pb was the highest contributor to the reduction of HMs mass concentration (58.6%), while Cr (85.5% for cancer risk) and As (26.0% for non-cancer risk) were more prominent for the reduction of HM risks. The coal combustion and industrial emissions were vital contributors to the reduction of both PM_2.5 mass concentrations (contributed 34.0% and 7.8% to the reduction respectively) and health risks (contributed 36.1% and 25.7% to the cancer risk reduction respectively). Although the percentage mass contribution of traffic emissions increased (7.7% in 2013 and 21.9% in 2019), the associated risks decreased (contributed 26.8% to the cancer risk reduction). Furthermore, the results of RSDA consistently implied that coal combustion, industrial emissions and traffic emissions controls in the northeast/north-northeast, south and southwest of the studied area played important roles in the risk reductions, which mainly due to the risk reduction of air masses from NE/NNE, S and SW, and their strong influence to Tianjin. The RSDA method can quantify the health risks from different sources and directions, and the evaluation of contributors to the reductions of risks in this work would provide a meaningful reference for policy maker to control PM_2.5 emissions and protect population health.

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.

Human risk assessment of ash soil after 2020 wildfires in Pantanal biome (Brazil)

Wildfires have increased in the last years and, when caused by intentional illegal burnings, are frequently run out of control. Wildfire has been pointed out as an important source of polycyclic aromatic hydrocarbons (PAHs) and trace elements (TEs) — such as, As, Ni, and Pb — to environmental compartments, and thus may pose a risk to human health and to the ecosystem. In 2020, the Brazilian biome, Pantanal, faced the largest losses by wildfires in the last 22 years. Ashes from the topsoil layer in Pantanal were collected after these wildfires at 20 sites divided into the sediment, forest, PF, PS, and degraded sites. Toxicity and associated risks for human health were also evaluated. The areas highly impacted by wildfires and by artisanal gold mining activities showed higher concentrations for TEs and PAHs than the protected areas. Pb varied from 8 ± 4 to 224 ± 81 mg kg⁻¹, and total PAH concentration ranged between 880 ± 314 and 1350 ± 70 ng g⁻¹, at sites impacted by anthropogenic activities. Moreover, health risk assessments for TE and PAH indicated a potentially great risk for children and adults, via ingestion, inhalation, and dermal pathway. The carcinogenic risks exceeded reference values, for both TE and PAH, suggesting harmful conditions, especially for vulnerable groups, such as children and the elderly.

Dietary and drinking water intake of essential trace elements in a typical Kashin-Beck disease endemic area of Tibet, China

BACKGROUND

Essential trace elements (ETEs), such as copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), selenium (Se), zinc (Zn), are very important elements for human health.

METHODS

In this study, 89 drinking water samples and 85 highland barleys were collected from 48 villages in 11 townships, and the average daily dose (ADD) of ETEs were calculated, in addition, health effects of ETEs to rural residents in Luolong County, a typical Kashin-Beck disease (KBD) endemic area in Tibet, were assessed.

RESULTS

The mean concentrations of Cu, Fe, Mn, Mo, Se, Zn in drinking water were 0.278 ± 0.264 μg·kg^-1, 0.766 ± 0.312 μg·kg^-1, 0.411 ± 0.526 μg·kg^-1, 0.119 ± 0.223 μg·kg^-1, 0.155 ± 0.180 μg·kg^-1, and 0.804 ± 1.112 μg·kg^-1, respectively; and mean concentrations of Cu, Fe, Mn, Mo, Se and Zn in highland barley were 3.550 ± 0.680 mg·kg^-1, 81.17 ± 38.14 mg·kg^-1, 14.03 ± 1.42 mg·kg^-1, 0.350 ± 0.200 mg·kg^-1, 0.0028 ± 0.0056 mg·kg^-1, and 23.58 ± 3.10 mg·kg^-1, respectively. The ADD of Cu in the study area was appropriate; the ADD of Fe and Mn in each township were higher than the maximum oral reference dose recommended by the National Health Commission of China, indicating that Fe and Mn had non-carcinogenic health risks; the ADD of Mo and Zn in 36.36% and 54.55% of the townships exceeded the maximum oral reference dose; and 72.73% of the townships had insufficient ADD of Se. The ADD of Mo, Cu and Se in different townships was significantly correlated with the prevalence of KBD.

CONCLUSIONS

Therefore, in order to prevent and control the prevalence of KBD and ensure the health of local residents, it is necessary to reduce the intake of high concentrations of Fe, Mn and Zn in diet, as well as increase the intake of Mo, Cu, especially Se.

Urinary monohydroxylated polycyclic aromatic hydrocarbons in the general population from 26 provincial capital cities in China: Levels, influencing factors, and health risks

Polycyclic aromatic hydrocarbons (PAHs) derived from the incomplete combustion of organic materials are associated with adverse health effects. However, little is known about PAH exposure levels and their influencing factors on a large scale in developing countries. In this study, urinary monohydroxylated metabolites of PAHs (OH-PAHs), including the metabolites of naphthalene, fluorene, phenanthrene, pyrene, chrysene, and benzo[a]pyrene, were measured in 1154 samples in the general population nationwide from 26 provincial capitals in China. Concentrations of OH-PAHs ranged from 1.39 to 228 μg/L. OH-Nap, metabolite of naphthalene, was the predominant compound, accounting for 65.1% of totals. People in eastern, southwest and northeast China, such as Shanghai, Kunming, Nanning, and Changchun, suffered more PAH exposure than other regions which might associate with sampling time, living habits of the subjects, and the imbalance of economic development and energy consumption across regions. Urinary OH-PAH concentrations were associated with body mass index, gender, and age, and smoking was the main correlating factor. Inhalation and diet might be the main exposure route of human exposure to PAHs, especially for smokers by inhalation. Hazard indices showed that no subject was exposed to PAHs with potential non-carcinogenic risk. Furthermore, the carcinogenic risk was the most significant health effects, with almost all subjects having carcinogenic risk values higher than the acceptable level of 10^-6. Naphthalene and phenanthrene were the main contributors. The results also suggested a possible relationship between PAH exposure and lung cancer in the Chinese population. This first nationwide study on human internal exposure to PAHs provides a large body of scientific information for governmental decision-making about associated human health and the prevention of human exposure to PAHs.

Investigation of Indoor Polycyclic Aromatic Hydrocarbons (PAHs) in Rural Northeast China: Pollution Characteristics, Source Analysis, and Health Assessment

Due to the low winter temperatures in rural areas of Northeast China, biomass fuels are widely used for heating and cooking, resulting in increased concentrations of PAHs in rural indoor areas during the heating period and threatening human health. Therefore, exploring the pollution characteristics, source localization, and risk assessment of indoor PAHs in rural Northeast China is of great significance for improving rural indoor air quality. In this study, PAHs were collected from a residential building in rural Northeast China for one consecutive year (January 2020–December 2020), and their concentrations were determined to explore the distribution patterns and sources of PAHs to further assess the carcinogenic risk of PAHs to humans. The results of the study showed that the average concentration of indoor PAHs in rural areas during the heating period (93.02 ng/m3) was about 1.81 times higher than that of the non-heating period (51.26 ng/m3). The main sources of PAHs were mixed combustion of biomass and coal, motor vehicle emissions, and domestic waste combustion. The level of indoor PAHs pollution has posed a carcinogenic risk to the health of the rural population in the Northeast.

Estimating household exposure to moth repellents p-dichlorobenzene and naphthalene and the relative contribution of inhalation pathway in a sample of Japanese children

p-Dichlorobenzene (DCB) and naphthalene (NP) used as moth repellents in indoor environments are suspected to be carcinogenic. To evaluate their adverse effects on health with chronic exposure in the general population, especially children, we need to know their amounts absorbed by the body and the relationships between their amounts and air quality in residences. At present, little is known worldwide about them. This study examined the daily intakes of DCB and NP by Japanese children via all exposure pathways and the contribution of indoor air quality to the intakes. First-morning void urine samples from the subjects aged 6 to 15 years and air samples in their bedrooms were collected. Airborne NP and DCB and their urinary metabolites were measured. Significant correlations were detected between their airborne concentrations and the urinary excretion amounts of their corresponding metabolites. The absorption amounts of DCB and NP by inhalation of the children while at home were calculated to be 26 and 2.0 ng/kg b.w./h, respectively, as median values. The daily intake was estimated to be 2.4 and 0.90 μg/kg b.w./d (median), respectively. The fractions (median) of inhalation absorption amounts to overall absorption amounts for DCB and NP were 30% and 5%, respectively. In children living in residences where the indoor air concentrations of these compounds were more than half the level of each guideline value for indoor air quality, the main exposure route for their absorption was considered to be inhalation while at home. The indoor concentrations of DCB exceeded the lifetime excess cancer risk level of 10^-4 in 22% of the residences and 10^-3 in 9% of them. Our findings indicate the need to further reduce airborne concentrations of DCB in Japanese residences to prevent its adverse effects on the health of Japanese children.

Century-long record of polycyclic aromatic hydrocarbons from tree rings in the southeastern Tibetan Plateau

Limited studies have been carried out on the historical variations of atmospheric polycyclic aromatic hydrocarbons (PAHs), especially in remote regions of the world. In this study, century-long record of PAHs (1916-2018) were reconstructed from tree rings in the remote southeastern Tibetan Plateau (TP). The total concentrations of 15 PAHs varied from 27.5 to 6.05 × 10² ng/g dry weight (dw), with a mean value of 1.40 × 10² ng/g dw. Higher levels of PAHs were observed during World War Ⅱ and the Peaceful Liberation of Tibet, and increasing trends were observed starting from rapid industrialization in India. Both the isomer ratios and the positive matrix factorization model results indicated biomass and coal combustion were the dominant sources of PAHs. The carcinogenic risk of PAHs to local residents was assessed, which might have been negligible in most past periods and lower than in other regions of the world. Nevertheless, since the beginning of the 21st century, the cancer risk has been increasing year by year, indicating more actions are needed to reduce emissions of PAHs. This study provides an idea for reconstructing the pollution history of PAHs at the global scale.

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.

Inhalation exposure to size-segregated fine particles and particulate PAHs for the population burning biomass fuels in the Eastern Tibetan Plateau area

Indoor biomass burning produces large amounts of small particles and hazardous contaminants leading to severe air pollution and potentially high health risks associated with inhalation exposure. Personal samplers provide more accurate estimates of inhalation exposure. In this study, inhalation exposure to size-segregated particles and particulate polycyclic aromatic hydrocarbons (PAHs) for the biomass user was studied by deploying personal samplers. The study found that daily PM_2.5 inhalation exposure level was as high as 121 ± 96 μg/m³, and over 84% was finer PM_1.0. For PAHs, the exposure level was 113 ± 188 ng/m³, with over 77% in PM_1.0. High molecular weight PAHs with larger toxic potentials enriched in smaller particles resulting in much high risks associated with PAHs inhalation exposure. Indoor exposure contributed to ~80% of the total inhalation exposure as a result of high indoor air pollution and longer residence spent indoor. The highest exposure risk was found for the male smoker who conducted cooking activities at home.

Polycyclic and nitro-polycyclic aromatic hydrocarbon pollution characteristics and carcinogenic risk assessment of indoor kitchen air during cooking periods in rural households in North China

Medium-flow atmospheric samplers were used to collect particulate (PM_2.5) and gaseous samples from the indoor kitchen of each of 35 randomly selected rural houses in North China while a meal was being cooked. The concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) and 9 nitro-PAHs (NPAHs) in the samples were quantified by high-performance liquid chromatography (HPLC). This study provided the real PAH and NPAH pollution characteristics and carcinogenic risk produced by cooking in rural indoor kitchens in North China. The mean PAH and NPAH concentrations in air in the indoor kitchens during cooking periods were 4049.1 and 1741.6 ng/m³, respectively. The PAH and NPAH concentrations were lower in the particulate phase than the gaseous phase. The mean PAH and NPAH concentrations were much higher for cooking using coal than for cooking using liquefied petroleum gas (LPG) or electricity. The PAH and NPAH benzo[a]pyrene toxic equivalent (TEQ_BaP) concentrations for cooking using coal were 1823.3 and 2760.9 ng/m³, respectively. Lower PAH and NPAH concentrations were found in kitchens with than without range hoods. Range hoods decreased the PAH and NPAH TEQ_BaP concentrations by 68.8% and 61.9%, respectively. Appropriate fuel and ventilation choice will improve air pollution in indoor kitchens during cooking. The results provide important evidence for changing cooking habits and developing policies for cooking in rural China.

Unraveling the behaviors and significances of waste biomass ashes as underlying emission sources of soil polycyclic aromatic hydrocarbons in Tibetan Plateau

Domestic consumption of biomass fuels has been found as a leading source of polycyclic aromatic hydrocarbons (PAHs) in pristine regions. The biomass ashes would serve as both source and vector for PAHs, which may threaten residents' health. However, research focusing on the behaviors of waste biomass ashes acting as emission resources of PAHs is still lacking. In present study, occurrence and fate of PAHs released from disposal biomass ashes in the Tibetan Plateau were investigated by evaluating their patterns and levels in soils at different distances from the Lhasa landfill. Concentrations of 16 PAHs averaged at 1009 ng/g dry weight and 103 ng/g dry weight in landfill cover soils and surrounding soils, respectively. The spatial distributions of PAHs evidenced the local source of biomass ashes in landfill, while the fractionations of PAHs in soils profiles emphasized the post-deposal leaching. Since PAH compositions altered significantly during their transport and sequestration, the rectification factors were suggested to adjust the source diagnostic ratios. In study area, the emission flux of PAHs from waste biomass ashes to soils was 0.93 ton/year; extended to the Tibetan Plateau, the flux was estimated to be 13.1-32.5 ton/year. This study confirmed that waste biomass ashes would represent significant contributions of PAH emissions in this pristine region, which might remarkably exacerbate the total emissions of PAHs in Tibet by more than 25%.

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.

Polycyclic aromatic hydrocarbons in soils and sediments in Southwest Nigeria

Polycyclic Aromatic Hydrocarbons are strongly associated with agricultural, residential, transportation, and industrial activities. This study determined by GC-MS the concentration of 15 PAHs in soil and sediments at different sites from the Awotan-Asunle dumpsite area in the Southwestern region of Nigeria, which is one of the largest dumpsites in Africa. The sources of contamination, toxicity and associated risks for human health were also evaluated. Total PAHs concentrations were from 489 to 5616 μg kg^-1, and 642-2159 μg kg^-1, for soil and sediment, respectively. For soils, the highest values were observed for indeno[1,2,3-c,d]pyrene, coronene, and phenanthrene, while for sediments, the most abundant species were pyrene, fluoranthene and phenanthrene. Diagnostic ratios were used to determine the sources of PAHs and suggested that the compounds were mainly emitted from non-traffic sources. The total BaP-TEQ and BaP-MEQ for soils did not exceed the value recommended by the Canadian guideline since the country does not present guidelines. The analysis of incremental lifetime cancer risk was high mostly for dermal and ingestion exposures in the population. This study might provide valuable information regarding exposure to PAHs in soils of a Nigerian community.

Estimation of human exposure to polycyclic aromatic hydrocarbons (PAHs) based on the dietary and outdoor atmospheric monitoring in the Czech Republic

In everyday life, humans can be exposed to various chemicals including ubiquitous polycyclic aromatic hydrocarbons (PAHs) mostly through food consumption and/or inhalation. In the presented study, we evaluated PAH concentrations in duplicate samples (n = 251). Concurrently, the outdoor concentrations of PM2.5-bound PAHs in filters (n = 179) were also monitored. The daily exposure to PAHs was subsequently estimated for the risk group of pregnant women living in two different cities (Most city and Ceske Budejovice city) in the Czech Republic. This is the first unique study in Europe to evaluate human daily exposure to 20 PAHs both from inhalation (outdoor air) and dietary intake. For the analysis of samples collected during the years 2016/2017, a gas chromatography coupled to tandem mass spectrometry was applied. Focusing on the diet samples, a slightly higher sum of detected PAHs was measured in duplicates obtained from the mothers living in the Most city (0.115-186 ng g^-1) compared to the Ceske Budejovice city (0.115-97.1 ng g^-1). This could be due to a higher occurrence of major analytes (pyrene, phenanthrene and fluoranthene) and the different composition of daily diet. The values of toxic and most often detected substance, namely benzo[a]pyrene (BaP), were also higher by 35% in the Most city. Regarding the outdoor air contamination (only particulate phase - PM2.5 was assessed), here the opposite situation was observed, relatively higher amounts of all PAHs were monitored in the Ceske Budejovice city (median: 2.22 ng m^-3) than in the Most city (median: 1.07 ng m^-3). These higher PAH concentrations in the Ceske Budejovice city are probably caused by more intense traffic, higher population and also by the occurrence of old-fashioned heating plant. Depending on a seasonal variability, especially during the cold season, the concentrations of BaP exceeded the European average emission limit (1 ng m^-3) by 1.5-6 times. This highest inhalation exposure to all PAHs was observed in February. However, the dietary intake still represents the dominant contributor (>90%) to the total PAH exposure.

Comparative study of PM10-bound heavy metals and PAHs during six years in a Chinese megacity: Compositions, sources, and source-specific risks

To comparatively analyze source-specific risks of atmospheric particulate matter (PM), PM₁₀-bound polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) were synchronously detected in a megacity (Chengdu, China) from 2009 to 2016. Non-cancer risk (assessed by hazard quotient, HQ) of PAHs and HMs was within the acceptable level, while cancer risk (assessed by incremental life cancer risk (ILCR), R) of PAHs and HMs were 1.01 × 10^-4 and 9.40 × 10^-5 in DP and WP, which showed low risk. HMs dominated cancer (92.12%) and non-cancer (99.99%) risks. An advanced method named as joint source-specific risk assessment of HMs and PAHs (HP-SRA model) was developed to assess comprehensive source-specific risks. Gasoline combustion (contributed 9.6% of PM₁₀, 0.3% of HQ and 10.0% of R), diesel combustion (6.2% of PM₁₀, 0.2% of HQ and 10.7% of R), coal combustion (17.5% of PM₁₀, 1.8% of HQ and 13.4% of R), industrial source (9.1% of PM₁₀, 80.7% of HQ and 35.0% of R), crustal dust (28.1% of PM₁₀, 9.0% of HQ and 1.6% of R), nitrate (7.5% of PM₁₀, 1.1% of HQ and 6.2% of R) and sulphate & secondary organic carbon & adsorption (SSA, 19.6% of PM₁₀, 6.9% of HQ and 23.1% of R) were identified as main sources. For cancer risk, industrial sources and SSA posed the highest proportion. Higher levels of Co and Ni generated from industrial sources and Cr (Ⅵ), Cd and Ni absorbed in the SSA can result in high-risk contributions. Thus, controlling HMs levels in industrial emissions is essential to protecting human health.

Tree bark as a biomonitor for assessing the atmospheric pollution and associated human inhalation exposure risks of polycyclic aromatic hydrocarbons in rural China

Inhalation exposure to atmospheric polycyclic aromatic hydrocarbons (PAHs) is posing a great threat to human health. Biomass combustion in rural areas contributes greatly to the total PAH emission in China. To conduct a comprehensive risk assessment of ambient PAHs in rural China, a nationwide air sampling campaign was carried out in this study. The 16 U.S. Environmental Protection Agency priority PAHs in tree bark, which was employed as a passive air sampler, were analyzed. The summation of the 16 PAHs ranged from 11.7 to 12,860 ng/m³ in the air of rural China. The national median benzo(a)pyrene equivalent (BaP_eq) concentration was 18.4 ng/m³, with the range from 0.334 to 2497 ng/m³. The total inhalation carcinogenic risks of individual PAHs, with the exception for naphthalene, were very low (<1 × 10^-6) at most of the sampling sites. The national median excess lifetime lung cancer risk associated with inhalation exposure to atmospheric PAHs was 20.3 × 10^-6, corresponding to a population attributable fraction (PAF) of 3.38‰. Our estimations using tree bark were comparable to those reported in other studies and the uncertainties of the variables in the dataset were within the acceptable levels, demonstrating that tree bark is feasible for assessing the atmospheric PAH pollution and associated health risks. We feel that the outputs from this study can assist decision-makers focusing on protecting human health against exposure to atmospheric PAHs in rural China.