Source analysis and health risk assessment of polycyclic aromatic hydrocarbons in atmospheric PM2.5 in a district of Taizhou City from 2019 to 2021 / 环境与职业医学

Background Polycyclic aromatic hydrocarbons (PAHs), one of the main components of fine particulate matter (PM2.5), have a certain impact on ambient air quality, and long-term exposure to PAHs may pose potential health risks to human beings. Objective To identify the distribution characteristics and sources of PAHs in atmospheric PM2.5 in a district of Taizhou City from 2019 to 2021, and to evaluate the health risks of PAHs to the population in the area through the inhalation pathway. Methods From 2019 to 2021, air PM2.5 sampling was carried out at a state-controlled surveillance point in a district of Taizhou City for 7 consecutive days on the 10th-16th of each month, the sampling time was 24 h·d−1, and the sampling flow rate was 100 L·min−1. PM2.5 mass concentration was calculated by gravimetric method. A total of 16 PAHs were determined by ultrasonic extraction-liquid chromatography. Kruskal-Wallis H test was used to compare the distribution charac teristics of PAHs concentrations by years and seasons, characteristic ratio and principal component analysis (PCA) was used to analyze their sources, and a lifetime carcinogenic risk (ILCR) model was used to assess the health risk of PAHs. Results From 2019 to 2021, the annual average concentrations [M (P25, P75)] of ∑PAHs in atmospheric PM2.5 in the selected district of Taizhou City were 6.52 (2.46, 10.59), 8.52 (4.56, 12.29), and 3.72 (1.51, 7.11) ng·m−3, respectively, and the annual benzo[a]pyrene (BaP) excess rates (national limit: 1 ng·m−3) were 27.38% (23/84), 47.62% (40/84), and 19.04% (16/84), respectively, both presenting 2020> 2019 > 2021 (P<0.001, P<0.05). The ∑PAHs concentration distribution showed a seasonal variation, with the highest value in winter and the lowest value in summer (P<0.05). Among the atmospheric PM2.5 samples, the proportion of 5-ring PAHs was the highest, the proportion of 2-3-ring PAHs was the lowest; the proportion of 2-4-ring PAHs showed a yearly upward trend, and the proportion of 5-6-ring PAHs showed yearly downward trend (P<0.05). The characteristic ratio and PCA results suggested that the sources of sampled PAHs were mainly mixed sources such as dust, fossil fuel (natural gas), coal combustion, industrial emissions, and motor vehicle exhaust emissions. The ILCR (RILCR) of PAHs by inhalation for men, women, and children were 1.83×10−6, 2.35×10−6, and 2.04×10−6, respectively, and the annual average RILCR was 2.07×10−6, all greater than 1×10−6. Conclusion For the sampled time period, the main sources of PAHs pollution in atmospheric PM2.5 in the target district of Taizhou City are dust, fossil fuel (natural gas), coal combustion, industrial emissions, motor vehicle emissions, etc., and PAHs may have a potential carcinogenic risk to local residents.

Mediating role of neutrophil-lymphocyte ratio in association between polycyclic aromatic hydrocarbons and mild cognitive impairment / 环境与职业医学

Background As a group of environmental pollutants, polycyclic aromatic hydrocarbons (PAHs) are neurotoxic and may cause mild cognitive impairment (MCI) by inducing inflammation. Whether neutrophil-lymphocyte ratio (NLR), an inflammatory indicator, plays a mediating role in the relationship between PAHs exposure and MCI is unclear yet. Objective To investigate a potential mediating role of NLR in the association between exposure to PAHs and MCI in coke oven plant workers. Methods Eleven urine hydroxylated PAHs (OH-PAHs) of 530 coke oven plant workers were determined by high performance liquid chromatography tandem mass spectrometry. NLR was derived from participants' routine blood examination results using a fully automated haematology analyser. The associations between urinary OH-PAHs and MCI were analyzed by binary logistic regression, the associations between urinary OH-PAHs and NLR were analyzed by multiple linear regression, and the role of NLR in the relationship between urinary OH-PAHs and MCI was evaluated by mediating effect analysis. Results After controlling for confounding factors and other OH-PAHs, the results of binary logistic regression showed that for every e-fold (e is the base of the natural logarithm) increase in the concentration of 2-hydroxynaphthalene (2-OHNap) and 1-hydroxyphenanthrene (1-OHPhe), the OR (95%CI) values of reporting MCI positive were 1.21 (1.02, 1.43) and 1.25 (1.04, 1.51) respectively. For each unit increase of NLR, the OR (95%CI) of reporting MCI positive was 1.56 (1.12, 2.18). The results of multiple linear regression showed that each unit increase in natural log-transformed levels of 1-OHPhe was associated with 0.05 (95%CI: 0.01, 0.10) increase of NLR. The results of mediating effect analysis showed that the association between urinary 1-OHPhe and MCI was partially mediated by peripheral blood NLR, with a mediation ratio of 9.8%. Conclusion Exposure to PAHs in coke oven plant workers may increase the risk of reporting MCI positive partially through increased NLR in peripheral blood.

Relationship between polycyclic aromatic hydrocarbons internal exposure and lung function change among healthy college students / 中国学校卫生

Objective@#To investigate the relationship between urinary monohydroxylated metabolites of hydroxyl polycyclic aromatic hydrocarbons (OH-PAHs) and lung function, as well as the role of oxidative stress in these associations, so as to provide a scientific basis for air pollution control and policy formulation.@*Methods@#A panel study was carried out among 45 young healthy adults. Four follow up surveys and health examinations were conducted from November 2017 to October 2018 to measure lung function parameters [forced vital capacity (FVC), second forced expiratory volume in one second (FEV1), peak expiratory flow (PEF), FEV1/FVC, and forced expiratory flow between 25% and 75% vital capacity (FEF 25%~75% )], markers of exposure to 7OHPAHs [∑ 7OH PAHs], and markers of oxidative stress[8 hydroxy 2 deoxyguanosine (8 OHdG) and 8 isoprostaglandin F 2α (8 iso PGF 2α )]. The relationship between urinary PAH metabolites and lung function was quantified by linear mixed effects models. Mediation analysis was performed to assess the role of oxidative stress in the relationship between OH PAHs and lung function.@*Results@#The median values of FVC, FEV1, FEVI/FVC, PEF, and FEF 25%-75% were 4.37 L, 3.58 L, 83.00%, 4.38 L/s, and 3.32 L/s, respectively. The results showed that each 1 unit increase in log transformed value of 2 Hydroxyfluorene (2 OHFlu) was associated with a 5.05% decrease ( β %=-5.05%，95% CI =-8.85%--1.09%) in FVC, 4.15% decrease ( β %=-4.15%，95% CI =-7.94%- -0.22% ) in FEV1 and 5.87% decrease ( β %=-5.87%，95% CI =-11.35%--0.05%) in FEF 25%-75% , respectively. Each 1 unit increase in log transformed values of 2 OHFlu and 9 Phenanthrol (9 OHPhe) was associated with a 7.03% decrease ( β %=-7.03%，95% CI =-12.60%--1.11%) and a 7.08% decrease ( β%=-7.08%，95% CI =-13.50%--0.17%) in PEF, respectively. Additionally, urinary ∑ 7OH PAHs had a positive correlation with the levels of urinary 8 OHdG and 8 iso PGF 2α ( r =0.64, 0.69, P <0.01). Meanwhile, the levels of 8 OHdG mediated 17.06% and 15.71% of the association between 2 OHFlu with FVC and FEV1.@*Conclusion@#The finding reveales a negative relationship between urinary OH PAHs and lung function among young healthy adults. The 8 OHdG plays a mediated role in the correlation of 2 OHFlu with FVC and FEV1. Active relevant policies are needed to control air pollution and maintain the healthy living conditions of young people.

Characterization and application of exposure biomarkers of polycyclic aromatic hydrocarbons in diesel exhaust / 环境与职业医学

Diesel exhaust (DE), Group 1 carcinogen, is an important source of air pollutants. Studies show that DE exposure associates with elevated incidences of respiratory and cardiovascular diseases. The toxic effects of DE are closely related to its components. Polycyclic aromatic hydrocarbons (PAHs) are one of the main toxic components in DE and are often used as human exposure biomarkers to DE. However, the exposure assessment of DE using PAHs as biomarkers could be interfered due to the other sources of PAHs. Therefore, identification of highly specific and reliable PAHs sourced biomarkers of DE exposure has become a hotspot of current research. New biomarkers of DE may play an important role in determining human exposure to DE and establishing dose-response relationship of DE exposure and health outcomes of interest. This paper focused on current progress in terms of PAHs sourced biomarkers of human exposure to DE with the following aims: (1) to clarify the types of PAHs sourced biomarkers to DE; (2) to explore the applicability and limitations of PAHs sourced biomarkers for DE exposure assessment in occupational exposure and environmental exposure analysis; and (3) to summarize the analysis methods for PAHs sourced exposure biomarkers in human urine samples and compare the advantages and disadvantages of different analytical methods.

Measurement of pesticides in hair samples from pemphigus foliaceus and pemphigus vulgaris patients in Southeastern Brazil

Abstract Background Pesticides, mainly organophosphates (OP), have been related to increased risk of pemphigus vulgaris (PV) and pemphigus foliaceus (PF), nevertheless, their measurement has not been determined in pemphigus patients. Objective To evaluate pesticide exposure and pesticide measurement, comparing PV, PF and control groups in Southeastern Brazil. Methods Information about urban or rural residency and exposure to pesticides at the onset of pemphigus was assessed by questionnaire interview; hair samples from the scalp of PV, PF, and controls were tested for OP and organochlorines (OC) by gas-phase chromatography coupled to mass spectrometry. Results The minority of PV (2 [7.1%] of 28) and PF (7 [18%] of 39), but none of the 48 controls, informed living in rural areas at the onset of pemphigus (p = 0.2853). PV (33.3%), PF (38.5%), and controls (20%) informed exposure to pesticides (p = 0.186). Twenty-one (14.8%) of 142 individuals tested positive for OP and/or OC: PV (2 [6.3%] of 32) and PF (11 [25.6%] of 43) had similar pesticides contamination as controls (8 [11.9%] of 67) (p = 0.4928; p = 0.0753, respectively), but PF presented higher contamination than PV (p = 0.034). PV did not present any positivity for OP. Three (7%) PF tested positive for both OP and OC. Some PF tested positive for three or four OP, mainly diazinon and dichlorvos. Study limitation Lack of data for some controls. Conclusion Although the frequency of PV and PF patients exposed to pesticides was similar, pesticides were more frequently detected in hair samples from PF compared to PV. The cause-effect relationship still needs to be determined.

Evaluación de la exposición a Hidrocarburos Aromáticos Policíclicos, salud renal y respiratoria en población indígena de Tocoy, San Antonio, S.L.P., México / Evaluation of exposure to polycyclic aromatic hydrocarbons, renal and respiratory health in the indigenous population of Tocoy, San Antonio, S.L.P, México

Resumen La contaminación del aire interior es un problema de salud pública, ya que afecta a unos 2.600 millones de personas en todo el mundo que siguen cocinando con combustibles sólidos como la madera, los residuos de las cosechas, etc. Esta exposición aumenta el factor de riesgo de desarrollo de enfermedades crónicas. La población indígena es muy susceptible a estar expuesta a mezclas de contaminantes del humo de leña como los Hidrocarburos Aromáticos Policíclicos (HAPs) debido a los métodos tradicionales de cocción. El objetivo de este trabajo fue evaluar la exposición a HAPs por medio de 10 metabolitos hidroxilados en orina de la población indígena de la Huasteca Potosina, mediante cromatografía de gases acoplada a espectrometría de masas; por otro lado, la salud renal y pulmonar fueron evaluadas con una prueba general de orina y la toxina urémica Indoxil sulfato, esta fue evaluada por medio cromatografía líquida de alto rendimiento, y la función pulmonar con una espirometría. Los resultados indican la presencia de metabolitos hidroxilados en el 89,47% de las muestras de orina, los más frecuentes fueron el 1-OH-PIRENO, el 1,2-OH-NAFTALENO. El Indoxil sulfato se presentó en el 100% de las muestras y la media era de 193,4 ± 91,85 gg/L En cuanto a la salud pulmonar, los resultados indican que algunos sujetos presentan patrones respiratorios regulares e irregulares. Estos resultados indican que la población se encuentra expuesta de manera crónica a una mezcla de contaminantes en el aire que podría producir el desarrollo de daño en los pulmones y los riñones y aumentar el riesgo al desarrollo de enfermedades crónicas.

Abstract Interior air pollution is a public health concern, it affects about 2.6 billion people around the world who still cook using solid fuels such as wood, crop wastes, among others. This exposition increases the risk of the development of non-communicable diseases (NCDs). The indigenous population is very susceptible to being exposed to mixtures of pollutants from the wood smoke such as Polycyclic Aromatic Hydrocarbons (PAHs) due to traditional methods of cooking, heating and waste burning. Therefore, the objective of this work was to evaluate the exposure to PAHs through the application of 10 hydroxylated metabolites (OH-PAHs) in the urine of the indigenous population from the Huasteca Potosina, this by gas chromatography coupled to mass spectrometry and to assess renal health of the population at the time of the study, with a general test of urine and through the uremic toxin Indoxyl Sulfate (IS), this by high-performance liquid chromatography, and the and pulmonary health with spirometry. The results indicate the presence OH-PAHs in 89.47% of the urine samples, the most frequent metabolites were 1-OH-PYRENE, 2-OH-NAPTHALENE. IS was present in 100% of the samples in mean concentrations of 193.4 ± 91.85 gg/L. For pulmonary health, the results indicate some subjects have regular and irregular respiratory patterns. These results indicate that the population is highly exposed to a mixture of pollutants in the air that might damage the lungs and kidneys and increase the risk of NCDs development.

Caracterización y biomonitoreo de contaminantes orgánicos e inorgánicos en una zona ladrillera de San Luis Potosí / Characterization and biomonitoring of organic and inorganic contaminants in a brick-making area of San Luis Potosí

Resumen El sector ladrillero se caracteriza por la elaboración del ladrillo de forma artesanal donde utilizan técnicas rudimentarias, hornos de baja tecnología y diversos combustibles de poca calidad generando humos negros con gran cantidad de contaminantes. Por lo que el objetivo de este estudio fue caracterizar los metales en suelo, HAPs en aire y biomonitoreo de HAPs en trabajadores de la zona ladrillera "Las Terceras" San Luis Potosí, México. Con el fin de conocer la exposición laboral se determinó la concentración de HAPs en partículas PM10, se caracterizó el suelo de la zona de trabajo y se realizó un biomonitoreo de me-tabolitos hidroxilados HAPs (OH-HAPs) en orina de los trabajadores. En aire se encontraron 14 de los 16 HAPs prioritarios por la Agencia de Protección Ambiental en la fracción de PM10, con una concentración media de 5293,05 gg/m3 (3,11-10510,81). Los resultados del análisis químico de los polvos mostraron que están constituidos principalmente de cuarzo (SiO2) y arcillas (SiAlOx) con presencia de óxidos de Fe-Ti, fosfatos de tierras raras (Lantano, Cerio, Neodimio Torio), silicatos de zirconio, sulfatos de bario, óxidos de zinc. En el biomonitoreo participaron 42 trabajadores ladrilleros, los resultados de la exposición a OH-HAPs en orina demostraron la media total de los OH-HAPs de 15,7 (6,92-195) ng/ml. Estos resultados muestran que el monitoreo ocupa-cional de las zonas ladrilleras es importante debido al escenario de riesgo y a las condiciones precarias de este trabajo, además de la alta exposición a contaminantes que afectan la salud de los trabajadores y sus familias, así como la propuesta de estrategias que ayuden a minimizar los impactos ambientales y prevenir los efectos en salud de las poblaciones.

Abstract The brick-making sector is characterized by artisanal brick production using rudimentary techniques, low-tech kilns and various low-quality fuels that generate black fumes with a large amount of pollutants. Therefore, the objective of this study was to characterize metals in soil, PAHs in air and biomonitoring of PAHs in workers of the "Las Terceras" brick area in San Luis Potosí, Mexico. In order to know the occupational exposure, the concentration of PAHs in PM10 particles was determined, the soil of the work area was characterized and a biomonitoring of hydroxylated PAH metabolites (OH-HAPs) in the urine of the workers was carried out. In air, 14 of the 16 PAHs prioritized by the Environmental Protection Agency were found in the PM10 fraction, with an average concentration of 5293.05 gg/m3 (3.11-10510.81). The results of the chemical analysis of the dusts showed that they are mainly constituted of quartz (SiO2) and clays (SiAlOx) with presence of Fe-Ti oxides, rare earth phosphates (Lanthanum, Cerium, Neodymium Thorium), zirconium silicates, barium sulfates, zinc oxides. The biomonitoring involved 42 brick workers, the results of OH-HAPs exposure in urine showed the mean total OH-HAPs of 15.7 (6.92-195) ng/ml. These results show that occupational moni-toring of brick-making areas is important due to the risk scenario and the precarious conditions of this work, in addition to the high exposure to pollutants that affect the health of workers and their families, as well as the proposal of strategies that help minimize environmental impacts and prevent health effects on populations.

Health Risk Assessment of PAHs from Wheat (Tritcum specie) Bambara Nut (Vigna subterranea) and Pigeon Peas (Cajanus cajanifolia) Consumed in Nigeria

Polycyclic aromatic hydrocarbons, PAHs are carcinogenic and genotoxic in nature and have been of worldwide concern. This study aimed at determining the PAH contamination levels in types of wheat (Tritcum specie), bambara groundnut (Vigna subterranea) and pigeon peas (Cajanus cajanifolia) commonly consumed in the eastern part of Nigeria and assess the health risk associated with their consumption. The grain samples were analyzed of sixteen priority PAHs using gas chromatography coupled with flame ionization detector, GC-FID after extraction by sonication. Estimation of daily intakes were carried out using adult male and female consumers while margin of exposure was used to assess the health risk applying bench mark dose levels for the indicators-BaP, PAH2, PAH4 and PAH8. The sixteen PAHs were detected in all the analyzed grains. The ∑16 PAHs concentrations (× 10¯²µg/kg) detected ranged from 25.004±20.553 in white pigeon peas to 36.493±20.305 in red pigeon peas. The eight probable carcinogenic PAHs (∑PAH8) detected ranged from 10.913±4.295 to 17.444±7.023 also in white and red pigeon peas respectively. From the estimation of daily intake calculated, the total dietary exposure of male (41.42 µg/kg bw/day) was less than that of female (48.24 µg/kg bw/day) implying that adult female are more exposed. The MOE for adult male individual ranged from 49,893 in pure white bambara groundnut to 392,943 in pigeon peas. While for adult female individual, the values of MOE ranged from 48,110 in bambara groundnut to 336,770 in pigeon peas. The values of margin of MOE obtained for all the indicators were much higher than 10000 which according to EFSA indicate low concern for human health and considered low priority for risk management actions. The PAHs values detected were all below 1.0 µg/kg which is the permissible limit established by EFSA. Based on these facts, these grains are safe for consumption.

Association between urinary polycyclic aromatic hydrocarbons metabolites and high-normal blood pressure in coke oven workers / 中国职业医学

@#Objective （ ） To investigate the association between urinary polycyclic aromatic hydrocarbons PAHs metabolites - Methods and high normal blood pressure in coke oven workers. A total of 433 coke oven workers were selected as the study - subjects using convenient sampling method. They were divided into normal blood pressure group and high normal blood pressure group according to their blood pressure level. The levels of ten kinds of urinary hydroxylated PAHs metabolites were measured by - Results - high performance liquid chromatography mass spectrometry. Among the subjects,57.5% had high normal blood - ， - ， - pressure. The levels of 1 hydroxynathalene 2 hydroxyphenanthrene 1 hydroxyphenanthrene and the metabolite of total PAHs - （ P ） in the high normal blood pressure group were higher than those in the normal blood pressure group all <0.05 . The results of - ， - ， - ， the multivariate logistic regression analysis showed that urinary 1 hydroxynathalene 2 hydroxyfluorene 3 hydroxychrysene - （ P ）， and metabolite of total PAHs were all risk factors for high normal blood pressure in coke oven workers all <0.05 after ， ， ， ， ， adjusting for confounding factors such as gender length of service body mass index smoking index alcohol consumption tea ， ， ， Conclusion consumption night shift exercise frequency and other PAHs metabolites. Exposure to PAHs in coke oven plants may increase the risk of elevated blood pressure within the normal range among coke oven workers.

Correlation between exposure to polycyclic aromatic hydrocarbons during pregnancy and placental mitochondrial DNA copy number / 预防医学

Objective@#To examine the correlation between exposure to polycyclic aromatic hydrocarbons ( PAHs ) and placental mitochondrial DNA ( mtDNA ) copy number among pregnant women, so as to provide the evidence for evaluation of potential effects of PAHs exposure during pregnancy on offspring health.@*Methods@#A total of 200 pregnant women delivered at a tertiary hospital in Urumqi City during the period from January to October 2019, and their newborns were recruited, and grouped according to the time of delivery, including the heating group [delivery during the heating period ( from January to April ) ] and the non-heating group [delivery during the non-heating period (from July to October) ]. Subjects'age, ethnicity, educational level and type of home heating were collected, and the total concentration of 16 PAHs was determined in the blood samples of pregnant women and their babies using gas chromatography-mass spectrometry. Placental DNA was extracted, and placental mtDNA copy number was measured using real-time fluorescence quantitative PCR assay. In addition, the correlation between PAHs concentration and placental mtDNA copy number was examined using the Spearman rank correlation analysis.@*Results@#There were 100 subjects in the heating group, which had a median age of 29 ( interquartile range, 3 ) years and had a mean gestational age of ( 275.06±0.72 ) days, and there were 100 subjects in the non-heating group, which had a median age of 29 ( interquartile range, 4 ) years and had a mean gestational age of ( 276.82±0.66 ) days. The total concentration of PAHs in the blood of pregnant women [15.71 (4.30) vs. 12.98 (5.49) μg/L; P<0.05 ], the total concentration of PAHs in neonatal blood [ 14.29 (4.25) vs. 11.24 (5.09) μg/L; P<0.05 ] and the placental mtDNA copy number [4.67 (1.18) vs. 4.51 (0.62); P<0.05] were all higher in the heating group than in the non-heating group. Spearman rank correlation analysis revealed that the total concentration of PAHs in the blood of pregnant women and neonates was positively correlated with placental mtDNA copy number ( rs=0.240, P=0.001; rs=0.273, P<0.001 ), and the total concentration of PAHs in the blood of pregnant women was positively correlated with the placental mtDNA copy number in the heating group ( rs=0.245, P=0.014 ), while the PAHs concentration in the neonatal blood was positively correlated with the placental mtDNA copy number in the non-heating group ( rs=0.292, P=0.003 ).@*Conclusions@#Exposure to PAHs positively correlates with placental mtDNA copy number among pregnant women, and there is a correlation between maternal exposure to PAHs and neonatal oxidative stress.

Variations and health risk of polycyclic aromatic hydrocarbons in ambient PM2.5 in industrial and residential areas in Fuzhou City / 环境与职业医学

Background PM2.5 pollution has become a widely concerned environmental health problem. Polycyclic aromatic hydrocarbons(PAHs) are the main harmful components of PM2.5, and their sources and carcinogenic risk deserve attention. Objective To analyze the source apportionment of PAHs in ambient PM2.5 in Fuzhou, and to evaluate the potential carcinogenic risk through inhalation due to exposure to PAHs. Methods In this study, two sampling sites were set up in Cangshan (industrial area) and Taijiang (commercial and residential area) districts in Fuzhou City. PM2.5 was collected from 10th to 16th of each month from 2017 to 2020 by membrane filtration method. The concentrations of ambient PM2.5 were measured by weighing, and the concentrations of 16 PAHs, including naphthalene(NAP), acenaphthylene(ACY), acenaphthene(ACE), fluorene(FLU), phenanthrene(PHE), anthracene(ANT), fluoranthene(FLT), pyrene(PYR), benzo[a]anthracene(BaA), chrysene(CHR), benzo[b]fluoranthene(BbF), benzo[k]fluoranthene(BkF), benzo[a]pyrene(BaP), indeno[1,2,3-cd]pyrene(IcdP), dibenzo[a,h]anthracene(DahA), and benzo[g,h,i]perylene(BghiP), were determined by ultra-high performance liquid chromatography coupled with diode array detector and fluorescence detector. The concentrations of PM2.5 and PAHs were compared in the two districts and the concentrations of PAHs were also compared in different seasons. The diagnostic ratio [FLT/(FLT+PYR), IcdP/(IcdP+BghiP), BaA/(BaA+CHR), and BaP/BghiP] method and positive matrix factorization (PMF) analysis were used to determine the sources of PAHs in PM2.5 in Fuzhou. The excess carcinogenic risk (ECR) model was used to assess the potential health risk of inhalation exposure to PAHs. Results During 2017–2020, the M (P25, P75) concentration of ambient PM2.5 in Cangshan and Taijiang districts of Fuzhou were 35.0 (25.0, 47.5) and 34.0 (25.5, 46.0) μg·m−3 respectively, and the percentages of PM2.5 exceeding the national standard in Cangshan and Taijiang were 2.68% and 4.17%, respectively, without significant differences (P＞0.05). The M (P25, P75) concentrations of ΣPAHs in Cangshan was 5.03 (3.07, 7.67) ng·m−3, higher than that in Taijiang, 3.20 (2.05, 5.59) ng·m−3 (P＜0.05). The M (P25, P75) concentrations of PAHs monomers except ACY, FLU, and ACE in Cangshan were higher than those in Taijiang (P＜0.05). The concentrations of ΣPAHs in PM2.5 in four seasons in Cangshan were higher than those in Taijiang (P＜0.05). In both districts, the concentration of ΣPAHs in winter was higher than those in spring, summer, and autumn (P＜0.05). According to the diagnostic ratio method, the median ratios of FLT/(FLT+PYR) in the two districts ranged from 0.4 to 0.5, and those of IcdP/(IcdP+BghiP), BaA/(BaA+CHR), and BaP/BghiP were from 0.2 to 0.5, from 0.2 to 0.35, and less than 0.6, respectively. The results of PMF analysis showed the proportions of four factors in Cangshan were 37.9%, 13.2%, 24.0%, and 24.9%, respectively. The major load contributors to factor 1 included FLT, PHE, and PYR; to factor 2, FLU, ACY, and ACE; to factor 3, DahA; to factor 4, BghiP, IcdP, and BaP. The proportions of four factors in Taijiang were 23.6%, 19.3%, 22.0%, and 35.1%, respectively. The main load contributor to factor 1 was DahA; to factor 2, BghiP; to factor 3, FLT, PHE, and PYR; to factor 4, IcdP, BaP, BbF, BkF, CHR, and BaA. The benzo[a]pyrene equivalences (BEQ) in Cangshan and Taijiang districts were 1.87 ng·m−3 and 1.61 ng·m−3, respectively. The excess carcinogenic risks of PAHs through inhalation exposure was 3.83×10−6 and 3.30×10−6, respectively. Conclusion The complex sources of PAHs in ambient PM2.5 include dust, vehicle emissions, industrial emissions in Fuzhou, and are different in selected two districts. The level of PAHs in ambient PM2.5 may pose a potential carcinogenic risk to local population.

Pollution characteristics, sources, and risk assessment of polycyclic aromatic hydrocarbons in atmosphere of two districts of Lanzhou City from 2019 to 2020 / 环境与职业医学

Background Polycyclic aromatic hydrocarbons (PAHs) are one of the most widely distributed and harmful organic pollutants in the atmosphere. Objective To investigate the distribution characteristics and composition sources of PAHs in the atmosphere of two districts of Lanzhou from 2019 to 2020 and evaluate the health risks of PAHs via inhalation to different populations. Methods The PAHs concentrations in two urban areas (Chengguan District and Xigu District) of Lanzhou City from January 2019 to December 2020 were regularly monitored. Mann-Whitney U test was used to compare differences in target pollutant concentrations between the two areas. Diagnostic ratio method and principal component analysis were adopted for source identification. Incremental lifetime cancer risk (ILCR) model was applied to evaluate the health risks of PAHs. Results The M (P25, P75) PAHs concentrations in Chengguan District and Xigu District were 24.04 (14.59, 41.81) ng·m−3 and 25.97 (18.59, 42.56) ng·m−3, respectively, with no significant difference (Z=−0.970, P>0.05). As to seasonal distribution, most PAHs monomer concentrations in Chengguan District were higher than those in Xigu District in summer, and the concentrations of benzo[a]anthracene and benzo[g,h,i]perylene in Chengguan District were also higher than those in Xigu District in spring and autumn (P<0.05), but there were no significant differences in PAHs monomer concentrations between the two urban areas in winter (P>0.05). Ring number of PAHs exhibited seasonal fluctuations. In winter and spring, the highest proportions in Chengguan District and Xigu District were both 4-ring PAHs (37.32%-41.73%, 35.20%-39.66%), and in summer and autumn, the highest proportions were both 2- and 3-ring PAHs (39.38%-49.54%, 47.17%-51.23%). The results of diagnostic ratio method revealed mixed atmospheric PAHs sources in the two urban areas, including fossil fuel, coal, and biomass combustion. The results of principal component analysis showed that the cumulative contribution rate of the four principal component factors reached 79.54%. Principal component 1 included phenanthrene, anthracene, fluoranthene, pyrene, chrysene, benzo[a]anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, and benzo[a]pyrene; principal component 2 included acenaphthene and dibenzo[a,h]anthracene; principal component 3 was fluorene; principal component 4 was naphthalene. The results of health risk assessment showed that the ILCR values of adult males, adult females, and children in Chengguan District were 2.30×10−6, 2.16×10−6, and 1.73×10−6, respectively; and those in Xigu District were 1.58×10−6, 1.48×10−6, and 1.19×10−6, respectively; all were greater than 10−6. Conclusion PAHs pollution exists in the atmosphere of the two urban areas of Lanzhou City, mainly comes from mixed sources of fossil fuels, coal, and biomass burning, and may pose potential carcinogenic risks to the population.

Interaction between adverse pregnancy history and polycyclic aromatic hydrocarbon-DNA adducts on missed abortion / 环境与职业医学

Background The incidence rate of missed abortion is increasing year by year, but the etiology has not been fully elucidated. Adverse pregnancy history and exposure to polycyclic aromatic hydrocarbons (PAHs) may increase the risk of missed abortion. Objective To investigate the interaction between adverse pregnancy history and PAHs exposure on missed abortion in early pregnancy, and to provide evidence for the etiologic research of missed abortion. Methods A total of 114 pregnant women diagnosed with missed abortion in the Department of Obstetrics of the First Hospital of Shanxi Medical University from March to December 2019 were selected as the case group, and 139 pregnant women who visited the same hospital for voluntary induced abortion in the same period as the control group, to collect basic information and medical information of abortion, stillbirth, intrauterine growth retardation, and other adverse pregnancy history. Abortion villus tissues were collected to detect PAH-DNA adducts levels, stratified by pregnancy and adverse pregnancy history and grouped by quartile method: Q1 (< 404.61 ng·L−1), Q2 (404.61−453.75 ng·L−1), Q3 (453.76−506.72 ng·L−1), and Q4 (≥506.73 ng·L−1). SPSS 25.0 statistical software was used for χ2 test and multiple logistic regression, and additive and multiplicative models were used to investigate the interaction between adverse pregnancy history and PAH-DNA adducts level on missed abortion. The PAH-DNA adducts were grouped by tertiles and quartiles, and P33, P50, P67 and P75 were used as data cut points for sensitivity analysis. Results The proportion of adverse pregnancy history in the case group (32.46%) was higher than that in the control group (12.23%) (P < 0.001). Among 160 subjects with≥2 pregnancies, the proportion of adverse pregnancy history in the case group (57.81%) was higher than that in the control group (17.71%) (P < 0.001). The results of χ2 test stratified by pregnancy for different PAH-DNA adducts levels between the two groups showed that the PAH-DNA adducts level was associated with missed abortion in subjects with≥2 pregnancies (χ2=10.14, P=0.017). Being further stratified by adverse pregnancy history, the PAH-DNA adducts level in subjects with no adverse pregnancy history was associated with missed abortion (χ2=9.70, P=0.021). The results of logistic regression analysis showed that adverse pregnancy history (OR=5.88, 95%CI: 2.79−12.39) and PAH-DNA adducts (OR=3.01, 95%CI: 1.22−7.40) increased the risk of missed abortion, but no interaction between them was found. The relative excess risk of interaction (RERI), the attributable percentage of interaction (AP), and the synergy index (SI) and its 95%CI were 0.60 (95%CI: −0.58−1.77), 0.74 (95%CI: −0.83−2.30), and 0.20 (95%CI: 0.01−5.43), respectively. Conclusions Adverse pregnancy history and PAH-DNA adducts in pregnant women may increase the risk of missed abortion. The effect of the interaction between them on the occurrence of missed abortion is not supported by the current study.

Application of three statistical models in association between polycyclic aromatic hydrocarbons exposure and cognitive level in workers / 环境与职业医学

Background As a complex organic pollutant, polycyclic aromatic hydrocarbons (PAHs) exposure shares the common exposure characteristics of multiple hydroxyl metabolites. Most studies have analyzed independent effect of each PAHs metabolite and have adjusted for the potential confounding effects induced by other metabolites concomitantly, without considering possible interactions among them. Proper statistical methods are needed to study their toxic effects. Objective To explore the applicability of logistic regression, weighted quantile sum (WQS) regression, and Bayesian kernel machine regression (BKMR) in evaluating the correlation between mixed exposures to exogenous chemicals and health outcomes, compare the advantages and limitations of the three models, and propose analytical strategies for evaluating the health effects of mixed chemical exposure for application in the analysis of the association between PAHs exposure and cognition. Methods Urine samples were collected of workers from a coke oven plant and a water treatment plant in Shanxi Province, who participated in their routine employee healthexamination. Mono-hydroxylated PAHs were detected by high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS), cognitive function was assessed using the Montreal Cognitive Assessment (MoCA). A cut-off value of MoCA less than 26 was considered mild cognitive impairment (MCI). According to a predetermined inclusion and exclusion criteria, 1 051 cases were included in the final data analysis. Logistic regression, WQS regression, and BKMR were used to analyze the relationship between PAHs metabolites and MCI. Results The prevalence rate of reporting MCI among the 1 051 workers was 21.7% (228/1 051). The concentration of 2-hydroxynathalene (2-OHNAP) was the highest among the 11 PAHs metabolites with a median concentration of 0.30 μg·L−1, followed by 9-hydroxyphenanthrene (9-OHPHE) (0.26 μg·L−1). There were significant differences between the two groups in 2-OHNAP, 1-hydroxynaphthalene (1-OHNAP), 2-hydroxyfluorene (2-OHFLU), 9-OHPHE, 1-hydroxyphenanthrene (1-OHPHE), and 1-hydroxypyrene (1-OHPYR) (all Ps<0.05). In the logistic regression, 2-OHNAP and 2-OHPHE were associated with MCI, and the OR (95%CI) for reporting MCI was 1.28 (1.01-1.67) and 1.27 (1.00-1.72) for each 10-fold increase in 2-OHNAP and 2-OHPHE concentrations, respectively. In the WQS regression analysis, the WQS index was positively correlated with the prevalence rate of reporting MCI (OR=1.37, 95%CI: 1.10-1.72). In the BKMR analysis, compared with the median exposure levels of all chemicals, the overall effect was statistically significant when all PAHs metabolites concentrations were at or above their 30th percentile; when all exposures were at the 75th percentile, the risk of reporting MCI increased by 6%. Conclusion Based on the results of these three models, 2-OHNAP and 2-OHPHE are the most important factors related to cognitive. It is recommended to use a combination of traditional logistic regression and either WQS or BKMR to study the association between PAHs and MCI.

Mediating effect of serum BDNF level on association of occupational PAHs exposure with cognitive impairment in coke oven workers / 环境与职业医学

Background Long-term occupational polycyclic aromatic hydrocarbons (PAHs) exposure is an important risk factor for cognitive impairment. At the same time, it can also cause a decrease of brain-derived neurotrophic factor (BDNF). However, it is not clear whether BDNF plays a key role in the cognitive impairment of workers caused by occupational PAHs exposure. Objective To analyze the correlation between the levels of PAHs in the plasma of coke oven workers and cognitive impairment, and to explore the possible mediating effect of plasma BDNF level on the relationship between PAHs and cognitive impairment. Methods A cross-sectional survey was carried out to select 138 pairs of workers from a coking plant (exposure group) and an energy plant (control group) in a large enterprise in Taiyuan, and the matching variables included age, education level and smoking status. The basic data of the workers were collected by questionnaire. The cognitive function of the workers was assessed by the Montreal Cognitive Assessment (MoCA) scale. Fasting elbow venous blood was collected, the plasma concentrations of 16 PAHs were determined by high performance gas chromatography-mass spectrometry (GC-MS), and the plasma concentration of BDNF was detected by enzyme-linked immunosorbent assay (ELISA). Multiple linear regression model was used to analyze the relationship between 12 PAHs levels in plasma and MoCA scores, and Bootstrap method was used to analyze the mediating effect of BDNF in the relationship between these two indicators. Results The average (\begin{document}$\bar x \pm s $\end{document}) age of workers in the two groups was (48.46±5.04) years, the length of service was (21.45±9.78) years, and 58.7% of the participants reported their education level at secondary vocational school, high school, and above. The median level (25th and 75th percentiles) [M(P25, P75)] of plasma Σ12PAHs concentration of workers in the exposure group [20.937 (9.454, 38.387) μg·L−1] was significantly higher than that of the control group [9.997 (4.952, 23.770)μg·L−1] and the MoCA score (22.82±2.38) of the exposure group was significantly lower than that of the control group (24.60±5.67) (P<0.05). The plasma BDNF showed no significant difference between the exposure group [(29.99±9.80) μg·L−1] and the control group [(31.48±9.09) μg·L−1](P>0.05). Taking plasma PAHs as independent variable and MoCA score as dependent variable, after adjusting selected covariates, the results of multiple linear regression model showed that the MoCA score changed by −0.020 (95%CI: −0.035 - −0.005) for every 1 μg·L−1 increase of plasma Σ12PAHs. Low (<P33), medium ( P33~P66) and high (>P66) dummy variables were set according to the intertertile boundaries (8.31, 23.76) μg·L−1 of the plasma level of Σ12PAH of the workers. The change of MoCA score in the high concentration group versus the low concentration group was −1.167 (95%CI: −1.866 - −0.467). The MoCA score changed by 0.066 (95%CI: 0.012 - 0.119) for each 1 μg·L−1 increase in plasma BDNF level. The results of dichotomous logistic regression analysis showed that the risk of cognitive impairment in the high concentration group was 2.635 (95% CI: 1.085 - 6.398) times higher than that in the low concentration group. The results of mediating effect analysis showed that plasma BDNF level was an intermediate variable between PAHs and cognitive impairment, and 45.50% of PAHs-induced cognitive impairment risk was mediated by reduced BDNF level. Conclusion The level of plasma PAHs in coke oven workers is negatively correlated with MoCA score, and PAHs may mediate cognitive impairment by reducing plasma BDNF level.

Determination of eight volatile halogenated hydrocarbons in drinking water by headspace thermal desorption⁃gas mass spectrometry / 上海预防医学

ObjectiveTo establish a method for the determination of 8 volatile halogenated hydrocarbons in drinking water， including vinyl chloride， trichloroethylene， tetrachloroethylene， tetrachloromethane， chloroform， dichlorobromomethane， dichlorodibromomethane， and tribromomethane by headspace thermal desorption-gas mass spectrometry. MethodsThe water sample was kept in the headspace bottle at 60 ℃ for 40 min， and the volatile matter was transferred to the cold trap，subjected to thermal desorption， then analyzed by gas chromatography-mass spectrometry. ResultsThe linear ranges were 0.2‒20.0 μg·L-1 for vinyl chloride， 0.1‒20.0 μg·L-1 for chloroform， 0.02‒20.00 μg·L-1 for tetrachloromethane， 0.2‒20.0 μg·L-1 for trichloroethylene， 0.3‒20.0 μg·L-1 for dichlorobromomethane， 0.1‒20.0 μg·L-1 for tetrachloroethylene， 0.4‒20.0 μg·L-1 for dichlorodibromomethane， and 1.0‒20.0 μg·L-1 for tribromomethane. All the correlation coefficients were more than 0.997. The respective quantitative limits were 0.162， 0.073， 0.016， 0.184， 0.270， 0.071， 0.356 and 0.813 μg·L-1， and the respective recoveries were 98.0%‒101.0%， 102.0%‒110.0%， 99.2%‒101.0%， 95.5%‒96.2%， 96.0%‒102.0%， 100.0%‒102.0%， 99.0%‒105.0%， and 94.0%‒103.0%. ConclusionThe method is simple， sensitive， rapid， accurate and reliable， so it is applicable for the determination of 8 kinds of volatile halogenated hydrocarbons in drinking water.

Conflicto armado, contaminación y riesgos en salud: una evaluación de riesgo de tres fuentes de exposición ambiental asociadas con el conflicto en Colombia / Armed conflict, pollution, and health risks: A risk evaluation of three sources of environmental exposure associated with the conflict in Colombia

Resumen | Introducción. Los conflictos armados afectan los territorios ricos en recursos y biodiversidad; el daño ambiental causado por las acciones violentas puede afectar la salud de las poblaciones. Objetivos. Evaluar los riesgos para la salud humana debidos a la degradación ambiental asociada con tres acciones violentas en el marco del conflicto armado colombiano: la voladura de oleoductos, la minería informal con mercurio y la aspersión de cultivos ilícitos con glifosato. Materiales y métodos. Se hizo una evaluación cuantitativa de los riesgos para la salud individual asociados con actividades del conflicto armado, usando metodologías que tienen en cuenta la ruta de dispersión de los contaminantes, su concentración en el ambiente, la exposición de los individuos y los riesgos de efectos cancerígenos y no cancerígenos. Resultados. La evaluación de los riesgos asociados con las acciones en el marco del conflicto armado analizadas, evidenció un riesgo cancerígeno intolerable y uno no cancerígeno inaceptable debidos al consumo de agua y peces contaminados por hidrocarburos aromáticos policíclicos, mercurio y glifosato. Conclusiones. El estudio reafirmó las conexiones inextricables que existen entre ambiente, sociedad y salud, y las implicaciones de la violencia ambiental para la salud pública de los grupos poblacionales vulnerables y, en general, para el bienestar de todos los seres vivos afectados por el conflicto armado.

Abstract | Introduction: Armed conflicts affect territories rich in resources and biodiversity. As a result of the environmental damage caused by violent actions, the health of populations can be affected. Objectives: To assess the risks to human health due to environmental degradation associated with three violent actions in the context of the Colombian armed conflict: Pipeline bombing, informal mining with mercury, and spraying of illicit crops with glyphosate. Materials and methods: We conducted a quantitative evaluation of the risks to individual health associated with armed conflict activities using methodologies focused on the routes of pollutants dispersion, their concentrations in the environment, the exposure of the individuals, and the risks of carcinogenic and non-carcinogenic effects. Results: The risk assessment of the armed conflict-related actions under study evidenced intolerable carcinogenic risk and unacceptable non-carcinogenic risk due to the consumption of water and fish contaminated by polycyclic aromatic hydrocarbons (PAH), mercury, and glyphosate. Conclusions: The study reiterates the inextricable connections existing among the environment, society, and health, as well as the implications of environmental violence for the public health of vulnerable population groups and, in general, for the well-being of all living beings affected by the armed conflict.

IDENTIFICATION OF ENDOPHYTIC BACTERIA OF SEEDS FROM Cedrela odorata L. (Meliaceae) WITH BIOTECHNOLOGICAL CHARACTERISTICS / Identificación de bacterias endófitas de semillas de Cedrela odorata L. (Meliaceae) con características biotecnológicas

ABSTRACT In the present study, 62 endophytic bacterial strains of cedar seeds (Cedrela odorata L.), collected in the municipalities of Huehuetán, Motozintla, and Pijijiapan in the state of Chiapas, Mexico were isolated. The goal was to identify characteristics of biotechnological interest such as biocontrol, promotion ofplant growth, and growth in aromatic compounds. The strains were identified by the partial sequence of the 16S ribosomal gene as belonging to the Bacillus genus. The biocontrol capacity of phytopathogenic fungi, production of indoleacetic acid (IAA), solubilization of phosphate, and growth in xenobiotic compounds (phenanthrene, benzene, anthracene, or phenol) were detected in 26 strains of the 62 isolates. 21 % of the strains inhibited the mycelial growth of Alternaria solani and Fusarium sp., and 13 % of the Phytophthora capsici oomycete. IAA production was detected in 24 isolates, phosphate solubilizing activity was identified in 18 isolates, while the ability to grow in the presence of phenanthrene and benzene was found in 26 isolates; 24 isolates grew in the presence of anthracene and only two isolates grew in phenol as the only carbon sources. This is the first report of the isolation and identification of endophytic bacteria from cedar seeds, where biotechnological characteristics were detected for biological control, promotion of plant growth, and growth in the presence of xenobiotic compounds.

RESUMEN En el presente estudio se aislaron 62 cepas bacterianas endófitas de semillas de cedro (Cedrela odorata L.) colectadas en los municipios de Huehuetán, Motozintla y Pijijiapan en el estado de Chiapas, México, con el objetivo de identificar características de interés biotecnológicas como biocontrol, promoción del crecimiento vegetal y crecimiento en compuestos aromáticos. Las cepas se identificaron por la secuencia parcial del gen 16S ribosomal como pertenecientes al género Bacillus. En 26 cepas de las 62 aisladas se detectaron la capacidad de biocontrol de hongos fitopatógenos, la producción de ácido indolacético (AIA), la solubilización de fosfato y el crecimiento en compuestos xenobióticos (fenantreno, benceno, antraceno o fenol). El 21 % de las cepas inhibió el crecimiento miceliar de Alternaria solani y Fusarium sp., y el 13 % del oomiceto Phytophthora capsici. La producción de ácido indolacético se detectó en 24 aislados y la actividad solubilizadora de fosfato se encontró en 18 aislados, mientras que la capacidad de crecer en presencia de fenantreno y benceno se manifestó en 26 aislados (24 aislados crecieron en presencia de antraceno y solo dos aislados crecieron en fenol como únicas fuentes de carbono). Es importante mencionar que este es el primer reporte del aislamiento e identificación de bacterias endófitas de semillas de cedro, en el que se detectaron características biotecnológicas para el control biológico, la promoción del crecimiento vegetal y el crecimiento en presencia de compuestos xenobióticos.

Estudo de tecnologias de investigação ambiental em alta resolução para refinamento do modelo conceitual — estudo de caso: Duque de Caxias (RJ), Brasil / Study of high-resolution site characterization technologies for the improvement of the conceptual site model — case study: Duque de Caxias (RJ), Brazil

RESUMO Este trabalho apresenta os resultados da utilização de duas técnicas de investigação geoambiental em alta resolução: investigação passiva de vapores do solo e investigação com o uso de Membrane Interface Probe (MIP), em uma área contaminada por hidrocarbonetos de petróleo, localizada no município de Duque de Caxias, Rio de Janeiro. O processo de gerenciamento ambiental da área iniciou-se em 2012 e contemplou as etapas preconizadas nas legislações vigentes. Os resultados obtidos a partir das investigações tradicionais foram insuficientes para a compreensão das características físicas e geoquímicas necessária para o sucesso das fases de diagnóstico e, consequentemente, da remediação. Portanto, duas investigações em alta resolução foram conduzidas com o objetivo de refinar o modelo conceitual de forma a atender adequadamente à Resolução CONAMA nº 420/09 e à Resolução CONEMA nº 44/12, permitindo ações futuras mais eficientes. A investigação passiva de vapores do solo utilizou amostradores compostos por materiais adsorventes granulares, encapsulados em uma membrana microporosa hidrofóbica e quimicamente inerte que permite a difusão dos vapores presentes no meio. Os resultados representam qualitativamente a presença de contaminação no subsolo. O MIP é uma ferramenta de direct push com medição em tempo real, que detecta a presença da contaminação tanto em meios insaturados quanto saturados inconsolidados. A partir dos resultados integrados, foi possível constatar que a distribuição de compostos orgânicos voláteis (volatile organic compounds (VOCs)) em água subterrânea ocorre de forma descontínua ao longo da área, sendo possível identificar cinco hotspots distintos e suas diferentes áreas fonte, incluindo uma região com presença de fase livre.

ABSTRACT This paper presents the results of two high-resolution site characterization (HRSC) techniques: passive investigation of soil vapors and investigation using Membrane Interface Probe (MIP), in an area contaminated by petroleum hydrocarbon, located in the municipality of Duque de Caxias, Rio de Janeiro. The environmental management process in the area began in 2012 and contemplated the stages recommended by the current legislation. The results obtained from the traditional investigations were insufficient for the understanding of the physical and geochemical aspects for the success of the diagnostic phases and, consequently, the remediation phase. Therefore, it was conducted two high-resolution investigations with the objective of improving the conceptual model in order to comply adequately with CONAMA Resolution 420/09 and CONEMA Resolution 44/12, allowing future actions more efficient. The soil gas passive investigation used samplers composed of granular adsorbent materials, encapsulated in a hydrophobic and chemically inert microporous membrane that allows the diffusion of the vapors present in the media. The results qualitatively represent the presence of contamination in the subsoil. MIP is a direct push tool with real-time measurement, which detect the presence of contamination in both unsaturated and saturated media. From the integrated results, it was possible to verify that the distribution of volatile organic compounds (VOCs) in groundwater occurs in a discontinuous way throughout the area. It was possible to identify five distinct hotspots and their different source areas, including a region with the presence of free-phase.

Determination of seven polycyclic aromatic hydrocarbons in water by dispersive liquid-liquid microextraction based on solidification of floating organic droplet with gas chromatography-mass spectrometry / 上海预防医学

Objective To develop a new method for the simultaneous determination of seven polycyclic aromatic hydrocarbons(PAHs)in water by dispersive liquid-liquid microextraction based on solidification of floating organic droplet(DLLME-SFO)with gas chromatography-mass spectrometry(GC-MS). Methods The experimental conditions of DLLME-SFO were determined with dodecanol as extractant solvent, methanol as dispersive solvent, inonic strength increased by adding 8% NaCl. After vortexed for 1 min and centrifuged at 4 000 r/min for 5 min, the water sample was cooled down in an ice bath till dodecanol became solid and formed a small ball. Then the solidified dodecanol phase was transferred, and directly detected by GC-MS method after it melted. Results Good linearities were obtained for the seven polycyclic aromatic hydrocarbons within the range of 5 μg/L-200 μg/L. The correlation coefficients were above 0.996. The detection limits ranged from 1.6 ng/L to 3.2 ng/L. The average recoveries ranged from 86.2% to 105% and the RSDs from 3.8% to 9.4%. Conclusion The method is sensitive, fast and simple. It has the advantage of little organic solvent consumption, which is friendly to environment and suitable for the detection of seven PAHs in water.