| Due to their well-known carcinogenic and mutagenic properties in humans, PAHs are a concern to more and more people and have been widely studied in various environmental and biologic compartments. PM2.5-bound PAHs can deposit deeply in the bronchioles and alveoli of the lungs, and are harmful to human health. Elderly are often at increased risk due to the physical conditions. In this research, PAHs exposure character of elderly was analyzed, and the health risk, PAHs potential soures were estimated. A total of101elderly participants living in two residential communities in Tianjin were recruited for the exposure study from June13to July2, and from November30to December12,2011. Personal exposure, indoor and region PM2.5samples were simultaneously monitored. And the first morning urine samples of elderly were collected after PM sample collecting, to analyze OH-PAHs and8-OHdG.The major results of the study included:1)The average concentration of PM2.5in region samples was98.6μg/m3(ranged from28.2to144.8μg/m3) in summer,140.0μg/m3(ranged from23.5to325.6μg/m3) in winter. China Environmental Protection Agency has recently established the PM2.5National Ambient Air Quality Class2Standard at35μg/m3for the annual standard and at75μg/m3for the24h standard. The PM2.5mass concentration in two seasons both exceeded the24h standard. The PM2.5bound-PAH concentration was16.56ng/m3in summer, BbF, InP and BP were the most abundant compounds. PAHs concentration was139.82ng/m3in winter, BbF, FluA and Chr were the most abundant compounds. Diagnostic ratio analysis and factor analysis indicated the major sources were vehicle emissions, coal combustion and industry emissions.2)In sumer, PM2.5concentration was122.0μg/m3for personal exposure sample,128.6μg/m3for indoor sample. And the concentration was164.8and169.2μg/m3，respectively for personal exposure and indoor samples in winter. The average PAHs concentrations of personal exposure samples in summer and winter were22.24and92.12ng/m3, respectively, and the PAHs concentrations of indoor samples were21.46and88.06ng/m3, respectively. In summer, low molecular weight PAHs (2-3rings) were the major compounds, accounting for over46%of the total PAHs, while in winter, higher molecular weight (4-6rings) were most abundant compounds, accounting for over80%of the total. PAHs in personal expouse samples were highly correlated with PAHs of indoor samples. A probabilistic risk assessment framework was integrated with the toxic equivalence factors (TEFs) and the incremental lifetime cancer risk (ILCR) approaches to quantitatively estimate the exposure risk for the elderly. In low exposure scenario, the median value of inhalation risk was estimated to be5.4×10-7. For10%of the high-risk population, the PAHs induced cancer rate was1.48×10-6. In the high exposure scenario, the median value of inhalation risk was estimated to be4.29×10-7, and for10%of the high-risk population, the PAHs induced cancer rate was1.31×10-5. The risk level higher than the acceptable level of10-6, posed an unacceptable potential cancer risk. Diagnostic ratio analysis and factor analysis indicated multiple sources contributed to the elder PAHs exposure, including vehicle emissions, coal combustion and industry and cigarette smoke.(3) In summer,7OH-PAH analytes were well detected, and in winter10OH-PAH analytes were well analyzed. Low molecular weight PAHs hydroxyl metabolites were the the most abundant compounds.The concentrations of1-and2-OH-Naphthalene were much higher than other analytes, accounting for over46%of the total. Good significant correlation was observed between PAHs hydroxyl metabolites.1-OHP was the most commonly used indicator in biomonitoring studies, the concentration exhibited significant difference between summer and winter. The average concentration of1-OHP in summer samples was lower than the reported dates in China, while in winter, the1-OHP concentration was even higher than the occupational exposure results, indicating potential health risk. The concentration of8-OHdG in morning urine samples was9.08μmol/molcr in winter, higher than the reported dates of healty adults, schoolchild and even some occupational exposure workers, suggesting potential health risk exsit for elderly.4) Good correlations were found between1-OHNaP,2-OHNaP,∑OHNaP and PM2.5-bound NaP, suggesting the PM2.5contribution to elderly exposure. However, no other significant corralations were observed between other urine metabolites and PM2.5-bound PAHs, indicating that ingestion could be the more exposure route for the general population. |
