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Although heavy metal pollution has developed into a major global environmental problem, most research has focused on specific elements, especially arsenic (As) and selenium (Se), and on the health risks to people in polluted areas or by occupation. This study investigated the urine of 480 participants from Guangzhou with a population of 18 million and targeted nine heavy metals: As, Se, chromium (Cr), manganese (Mn), nickel (Ni), cadmium (Cd), lead (Pb), antimony (Sb), and mercury (Hg). The heavy metals were widely detected, of which As, Se, Cd, and Pb all exceed 98%. Among the toxicants, As showed the highest concentration, followed by Se with 40.5 and 35.4 μg/L, respectively. The heavy metal levels from suburban subjects were generally higher than those in urban subjects (except for Sb), and the Cd level of males was lower than that of females. Concentrations were related to age, body mass index, alcohol consumption, and smoking. According to the health risk assessment, most subjects experienced potential non-carcinogenic risk from As, Cd, Se, and Hg, which accounted for 38.2%, 8.83%, 8.31%, and 3.38%, respectively. The carcinogenic risk of As and Cd surpassed the risk level of 10−6, and 90.1% and 35.4% of the subjects, respectively, exceeded 10−4, an unacceptable risk level. More attention to the high carcinogenic risk from heavy metals and the high detected levels of As and Cd is required.

Polycyclic aromatic hydrocarbons (PAHs) are compounds with two or more benzene rings whose hydroxylated metabolites (OH-PAHs) are excreted in urine. Human PAH exposure is therefore commonly estimated based on urinary OH-PAH concentrations. However, no study has compared PAH exposure estimates based on urinary OH-PAHs to measurements of PAH levels in blood samples. Estimates of PAH exposure based solely on urinary OH-PAHs may thus be subject to substantial error. To test this hypothesis, paired measurements of parent PAHs in serum and OH-PAHs in urine samples from 480 participants in Guangzhou, a typical developed city in southern China, were used to investigate differences in the estimates of human PAH exposure obtained by sampling different biological matrices. The median PAH concentration in serum was 4.05 ng mL−1, which was lower than that of OH-PAHs in urine (8.33 ng mL−1). However, serum pyrene levels were significantly higher than urinary levels of its metabolite 1-hydroxypyrene. Concentrations of parent PAHs in serum were not significantly correlated with those of their metabolites in urine with the exception of phenanthrene, which exhibited a significant negative correlation. Over 28% of the participants had carcinogenic risk values above the acceptable cancer risk level of 10−6. Overall, estimated human exposure and health risks based on urinary 1-hydroxypyrene levels were only 13.6% of those based on serum pyrene measurements, indicating that estimates based solely on urine sampling may substantially understate health risks due to PAH exposure.

“Swimming across the Pearl River” is an annual large-scale sporting event with great popularity in Guangzhou. To reduce the risk of swimmers’ exposure to various contaminants in the Pearl River during swimming activities, the local government limits direct sewage and effluent discharge from urban channels during the event. However, the impact of discharge reduction on some contaminants of emerging concern (CECs), such as organophosphorus flame retardants (OPFRs), bisphenol analogues (BPs), and triclosan remains unknown. In the present study, the concentrations of CECs, as well as ammonia-nitrogen (NH3-N), dissolved organic carbon, and chemical oxygen demand, were measured in aqueous and suspended particulate matter (SPM) from the Guangzhou reaches of the Pearl River. The concentration ranges of sixteen OPFRs, eight BPs, and triclosan were 21.2–91.0, 8.46–37.3, and 1.47–5.62 ng/L, respectively, in aqueous samples, and 25.2–492, 14.0–86.3, and 0.69–17.5 ng/g, respectively, in SPM samples. Hydrophobic and π-π interactions could be contributing to the distribution of CECs. Principal component analysis indicated that consumer materials, manufacturing, and domestic sewage might be the main sources of the CECs. In addition, our study showed that the concentrations of CECs did not change considerably before or after discharge reduction activities, although NH3-N showed a substantial decrease following pollution control measure. The results demonstrated that temporary reductions of contaminant discharges to the Pearl River had only limited effect on the levels of CECs. Further research is needed to investigate the distributions and potential health risks of CECs in the Pearl River.

Background Analyses of the effects of pit and fissure sealant have been based on small samples and lack large-scale field evaluation data in China. The aim of this study was to understand the effect of pit and fissure sealant in preventing caries in the first permanent molars (FPMs) of children in Guangzhou. Methods We conducted a population-based cohort study using the database of the pit and fissure sealant program of Guangzhou. The carious status and sealant retention of the FPMs were assessed in 4,822 school children who received pit and fissure sealant 3 years prior to the study. The control group included 4,396 children who had indications for receiving pit and fissure sealant but were not treated and were matched according to sex, age and school. Results In the sealant group, the rate of sealant retention in the FPMs was 72.2%. Children in the sealant group had a 37% decreased risk of dental caries compared with the control group (adjusted HR = 0.63 [95% confidence interval (CI), 0.57–0.69], P

Background The relationship between body dissatisfaction (BD) and health-related quality of life (HRQoL) has been well documented in adolescents and adults but is less clear in children, particularly in China. The aims of this study were to describe body image perception and dissatisfaction and to examine their effects on HRQoL among primary school students in Guangzhou, China. Methods A total of 5734 children aged 8–12 years from 29 schools completed self-report questionnaires, which included the Paediatric Quality of Life Inventory 4.0 for measuring HRQoL and Ma figural stimuli for measuring BD. Based on their level of BD, the children were divided into three groups: no dissatisfaction, mild dissatisfaction and moderate or high dissatisfaction. Based on the children’s perceptions of their own body image, the groups were also categorized into just right, too fat and too thin groups. Height and weight were objectively measured using standardized methods, and a BMI z-score was derived using the age- and sex-specific WHO references from 2007 for children aged 5–19 years. Weight status was classified as underweight, healthy weight, overweight or obese. Results A total of 78.10% of children aged 8–12 years in Guangzhou had different levels of BD; boys had slightly higher levels BD than girls (p

Background Nine COVID-19 (Corona Virus Disease, 2019) cases were observed in one community in Guangzhou. All the cases lived in three vertically aligned units of one building sharing the same piping system, which provided one unique opportunity to examine the transmission mode of SARS-CoV-2. Methods We interviewed the cases on the history of travelling and close contact with the index patients. Respiratory samples from all the cases were collected for viral phylogenetic analyses. A simulation experiment in the building and a parallel control experiment in a similar building were then conducted to investigate the possibility of transmission through air. Results Index patients living in Apartment 15-b had a travelling history in Wuhan, and four cases who lived in Apartment 25-b and 27-b were subsequently diagnosed. Phylogenetic analyses showed that virus of all the patients were from the same strain of the virus. No close contacts between the index cases and other families indicated that the transmission might not occur through droplet and close contacts. Airflow detection and simulation experiment revealed that flushing the toilets could increase the speed of airflow in the pipes and transmitted the airflow from Apartment 15-b to 25-b and 27-b. Reduced exhaust flow rates in the infected building might have contributed to the outbreak. Conclusions The outbreak of COVID-19 in this community could be largely explained by the transmission through air, and future efforts to prevent the infection should take the possibility of transmission through air into consideration. A disconnected drain pipe and exhaust pipe for toilet should be considered in the architectural design to help prevent possible virus spreading through the air., Highlights • Provide evidence of SARS-CoV-2 transmission through air. • Poor ventilation in the apartments increases the risk of transmission. • Floor drain should be sealed with water and regular disinfected. • The privately remodeled piping system might have played a role in this transmission.

To study the status of physical activities and its influencing factors among parents of primary and secondary school students, to provide basis for improving students' parents physical activities.A total of 12 501 parents ofprimary and secondary school students from Shenyang, Guangzhou, Chengdu and Wuhan were selected by stratified random cluster sampling. They completed a self-designed questionnaire that was derived from International Physical Activity Questionnaire( IPAQ). Logistic regression model was used to analyze the influence of region, stage of school, gender, age, education level, occupation and economic level on physical activities among parents of primary and secondary school students.The rate of students' parents with insufficient physical activity was 58. 3%, and the rate of students' parents spending2 h and more on sedentary activities per day was 55. 7%. Logistic regression analysis showed that compared with primary school students ' parents, the risk of insufficient physical activity and spending 2 h and more on sedentary activities of junior and senior middle school students' parents were decreased( the risk of insufficient physical activity:ORjunior( 95% CI) = 0. 796( 0. 728-0. 869), ORsenior( 95% CI) = 0. 746( 0. 683-0. 815); the risk of spending 2 h and more on sedentary activities: ORjunior( 95% CI) =0. 823( 0. 750-0. 904), ORsenior( 95% CI) = 0. 788( 0. 712-0. 872)). Compared with students' parents with primary school education, the risk of insufficient physical activity and spending 2 h and more on sedentary activities of parents with junior college or above education were increased( the risk of insufficient physical activity: OR( 95% CI) = 1. 288( 1. 107-1. 497); the risk of spending 2 h and more on sedentary activities: OR( 95%CI) = 1. 303( 1. 120-1. 515)). Compared with housework/unemployed/retirees, the risk of insufficient physical activity and spending 2 h and more on sedentary activities of agricultural/equipment operators were decreased( the risk of insufficient physical activity:OR( 95% CI) = 0. 755( 0. 634-0. 899); the risk of spending 2 h and more on sedentary activities: OR( 95% CI) = 0. 731( 0. 617-0. 867)).The rate of insufficient physical activity and spending 2 h and more on sedentary activities among students' parents were relatively higher. The influencing factors on physical activity level and sedentary activity time were region, stage of school, education level and occupation. Specific interventions should be developed for different people.

Little is known about the impact of air pollution on school children in developing countries. This paper aims to fill this gap by quantifying the causal effects of air pollution on the health status and the school attendance of the Chinese students. We relate the arguably exogenous daily variation in air pollution-instrumented by the occurrence of temperature inversion-with student illnesses and absences from more than 3000 schools in Guangzhou City. We find a sizable deleterious effect of air pollution on school attendance through the health channel. The impact persists for at least four days and displays a monotonically increasing pattern. Notably, this harmful effect is non-negligible even when pollution levels are below the official standards for air quality in China, suggesting that the current ambient air quality standards in China are not low enough to protect students.