Background Polycyclic aromatic hydrocarbons (PAHs), one of the main components of fine particulate matter (PM_2.5), 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 PM_2.5 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 PM_2.5 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. PM_2.5 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 PM_2.5 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 PM_2.5 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 (R_ILCR) 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 R_ILCR 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 PM_2.5 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.

Objective:To investigate the value of plasma Epstein-Barr virus (EBV) DNA detection in the screening of nasopharyngeal carcinoma (NPC) and its clinical application in non-high-risk areas.Methods:Plasma EBV DNA results in 1 153 newly diagnosed nasopharyngeal carcinoma patients who were treated in Sichuan Cancer Hospital from 2015 to 2020 and 244 healthy control cases with matched sex and age were retrospectively analyzed. EBV DNA were detected by quantitative real-time PCR. Positive rate of EBV DNA was determined by the cutoff value of 400 (≥400 copies/ml as positive) and optimization threshold method (presence of S amplification curve as positive). Further analyses were conducted to compare EBV DNA load in different clinical stage, TNM stage and regions distribution characteristics. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the diagnostic value of the cutoff value of 400 and optimization threshold method for NPC.Results:Compared with healthy controls, EBV DNA increased significantly in newly diagnosed NPC patients ( P<0.001). Both evaluation methods revealed that the EBV DNA positive percentage increased with TNM and clinical stage ( P<0.001). With 400 copies/ml as cutoff value, the diagnostic sensitivity and specificity were 40.85% and 100%, respectively. The area under the curve was 0.704 (95% CI 0.676-0.733, P<0.001). Evaluated by the optimization threshold method, the sensitivity and specificity could improve to 82.0% and 99.2%, respectively, and the area under the curve reached 0.910 (95% CI 0.894-0.924, P<0.001). Conclusions:In the low prevalence area of nasopharyngeal carcinoma, the sensitivity for diagnosis of nasopharyngeal carcinoma is only 40.9% by the 400 copies/ml cutoff value method. The optimization threshold method is a better choice to improve the diagnostic sensitivity without lowering the diagnostic specificity.

PurposeTo evaluate the feasibility of a low-dose contrast medium protocol for 64-slice spiral CT angiography (CTA) of cerebral and carotid using a low-tube-voltage setting, and to compare the display effect of cerebral and carotid arteries by low-tube-voltage low-dose contrast medium and routine-tube-voltage routine-dose contrast medium scanning, and to assess the effect on radiation dose.Materials and MethodsEighty consecutive patients were prospectively selected to perform cerebral and carotid CTA inspection. The patients were randomly divided into control group and low dose group with 40 people in each group. The voltage in control group was 120 kV and the contrast agent was 80 ml; those in low dose group were 80 kV and 50 ml, respectively. The artery image quality was evaluated and venous interference was scored. The CT value, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and radiation dose in both groups were statistically analyzed.Results The consistency of uniform in artery image quality score and venous interference score was rather high according to the assessment of two physicians (Kappa=0.782 and 0.867). There was no statistical difference in artery image quality score, venous interference score, SNR and CNR between the two groups (Z=-0.864--0.032,P>0.05). The CT value in low dose group was higher than that in control group (differences with statistical significance,t=-8.789-1.715,P<0.05). The CT dose index of volume, dose-length product and effective dose in low dose group were all signiifcantly lower than those in control group (Z=-8.888,t=78.092 and 78.350, respectively,P<0.05).Conclusion The use of low tube voltage and low contrast dose in cerebral and carotid CTA examination can result in high quality images which meets the diagnostic needs and obviously reduce radiation dosage.