Objective: To investigate the recessive infection rate of healthy children and guardians in different epidemic periods of hand, foot and mouth disease (HFMD) in Qingdao, analyze the risk factors affecting recessive infection, so as to provide the basis for HFMD prevention and control. Methods: In the nonepidemic period of 2022, the random cluster sampling method was used to selected 546 children and guardians from 4 childcare institutions in Laoshan District and Pingdu City. In the epidemic period of 2023, 690 children and guardians were selected from 6 childcare institutions in Shibei District, Laoshan District and Pingdu District. A questionnair survey was conducted in the epidemic period. Logistic regression analysis was used to analyze the factors affecting the recessive infection. Dominance analysis was used to explore the relative importance of the risk factors affecting recessive infection. Results: The results showed that the recessive infection rates of healthy children and guardians in the epidemic period were 18.84% and 13.62%, respectively; the recessive infection rates were 9.09% and 4.44% in the nonepidemic period, respectively. The results of multivariate Logistic analysis showed that rural areas (OR=4.71, 95%CI=2.57-8.61) and recessive infection of guardians (OR=18.62, 95%CI=7.45-46.56) were positively correlated with recessive infection of HFMD in healthy children (P<0.05). Washing hands (OR=0.09, 95%CI=0.04-0.20), using towels alone (OR=0.17, 95%CI=0.07-0.40), and EV71 vaccination (OR=0.42, 95%CI=0.20-0.87) were negatively correlated with recessive infection of HFMD in healthy children (P<0.05). Public toilets (OR=3.02, 95%CI=1.50-6.09) and drying bedding once per quarter (OR=3.89, 95%CI=1.75-8.68) were positively correlated with recessive infection of HFMD in healthy guardians. Housing with good lighting (OR=0.31, 95%CI=0.12-0.79), and tableware disinfection (OR=0.31, 95%CI=0.15-0.65) were negatively correlated with recessive infection of HFMD in healthy guardians (P<0.05). The results showed that recessive infection of guardians was relatively the most important for healthy children (41.51%), and tableware disinfection was relatively the most important for recessive infection of guardians (28.87%). Conclusions The recessive infections of HFMD are common among healthy populations in Qingdao, and the recessive infection rate among children during the epidemic period is relatively higher. Guardians play an important role in the recessive infection of healthy children. Therefore, healthy education should be strengthened for key populations, especially to enhance parents awareness of prevention and control to reduce the occurrence of recessive infections of hand, foot and mouth disease in children and guardians.

OBJECTIVE: To compare and analyze the risk of formaldehyde hazards in a plywood manufacturing factory using two risk assessment methods,and to evaluate the occupational health risk. METHODS: Occupational health investigation and formaldehyde detection for workplaces were carried out in a plywood manufacturing factory in Shandong province. The risk ratings of different posts were assessed by US Environmental Protection Agency( EPA) inhalation risk( EPA assessment model) and Singapore Semi-quantitative Assessment Model( MOM assessment model). The risk classification results of the 2 risk assessment methods were compared and analyzed. RESULTS: The concentration of airborne formaldehyde on the positions of shaving,woods feeding,gluing,hot milling,hot pressing,sanding and reprocessing were 0. 25,0. 13,1. 47,0. 72,0. 92 and 0. 58 mg/m~3,respectively. By the EPA assessment model,all of the positions were evaluated as high carcinogenic risk. Through the MOM assessment model,the feeding position was evaluated as medium risk,the positions of shaving,hot milling,hot pressing sanding and reprocessing were high risk,and the position of gluing was higher risk. CONCLUSION: It suggests that there is a high formaldehyde exposure in several posts in the plywood production processing. EPA assessment model is a suitable for occupational health risk assessment for formaldehyde exposure.

OBJECTIVE: To establish the cell model using human leukemia cell line HL-60 for exposure of coke oven emissions( COE) in vitro and to explore the mechanism of COE-induced acute toxicity in HL-60 cells. METHODS: HL-60 cells were collected in their logarithmic growth phase and cultured in medium that had final concentrations of COE in 2. 5,5. 0,10. 0 and 20. 0 mg / L for 24 hours. Cell survival rate was examined by CCK-8 assay. The cytotoxicity was evaluated using lactate dehydrogenase release assay. Reactive oxygen species( ROS) production was determined by the 2',7'-dichlorofluorescein diacetate and nitroblue tetrazolium method. The activation of nuclear factor-κB( NF-κB) pathway was evaluated by western blot. RESULTS: With the increasing exposure concentrations of COE,the cytotoxicity of HL-60 cells increased( P < 0. 01),the cell survival rate decreased( P < 0. 01),intracellular ROS decreased( P < 0. 01),whereas extracellular ROS increased( P < 0. 01). These changes had a dose-effect relationship. The levels of phospho-nuclear factor-kappa B p65 and phospho-inhibitor of kappa Bα were higher in all the COE-treated cells compared with untreated cells( P < 0. 05),with no dose-effect relationship. CONCLUSION: COE could cause acute toxicity in HL-60 cells in a doseeffect relationship. The mechanism may be related to the COE-induced in-balanced ROS release and removal,leading to the activation of NF-κB pathway. HL-60 cells can be used as a common cell line for COE hematotoxicity analysis.