Effects of professional toothbrushing among patients with gingivitis.

OBJECTIVES: This study aimed to evaluate the biological and clinical effect of professional toothbrushing on the periodontal health of patients with gingivitis. METHODS: We enrolled 21 university students with gingivitis in Jinju City in this study between April 24 and October 28, 2014. A dental hygienist performed a professional toothbrushing routine on the participants twice, once at baseline and after 3 months. Oral examinations were performed at baseline, 3, and 6 months to assess the periodontal health. The patient hygiene performance index, gingival bleeding rate, periodontal pocket depth, amount of gingival sulcus fluid, and number of bacterial colonies in the gingival sulcus (CFU/mL) were evaluated during the oral examination. RESULTS: The patient hygiene performance index, gingival bleeding rate, pocket depth, amount of gingival sulcus fluid, and CFU/mL within the gingival sulcus significantly decreased after professional toothbrushing (p < 0.05), indicating an improvement in the periodontal health. The patient hygiene performance index, gingival bleeding rate, pocket depth, amount of gingival sulcus fluid, and CFU/mL within the gingival sulcus decreased more among those whose pocket depth was 4-5 mm than among those whose PD was ≤3 mm (p < 0.05). CONCLUSIONS: Professional toothbrushing improved the periodontal health in patients with gingivitis in respect of both biological and clinical results.

Effects of Exposure to Lead and Cadmium on Health of Inhabitants of Abandoned Metal Mine Area in Korea.

People living near abandoned mines are at increased risk of exposure to toxic metals. We surveyed 4500 inhabitants with the mean age of 68.5 years old (male: 1768, female: 2732) living near 104 abandoned metal mines from 2013 to 2017 (the 2nd phase health survey in Korea). We conducted personal interviews, blood and urine sampling, and analyzed the concentrations of lead (Pb) and cadmium (Cd) in whole blood and Cd in urine using a graphite furnace atomic absorption spectrometer. The geometric means of blood Pb, blood Cd, and urine Cd were 2.27 µg/dL, 1.42 µg/L, and 1.66 µg/g creatinine, respectively. The level of metal exposure was lower than that reported from the first phase health survey in Korea (2008‒2011) but was higher than in the general population of Korea. Blood Pb was higher in males while blood Cd and urine Cd were significantly higher in females. Blood Pb was highest in the 40‒59 age group, while blood and urine Cd levels continuously increased until age 80 or older. The Cd levels in blood and urine were affected by consumption of locally produced rice and duration of residence near abandoned mines. Furthermore, negative correlations were observed between blood Pb and blood and urine Cd levels. Additionally, 252 of the 4500 subjects exceeded the thresholds of blood Cd or urine Cd levels. Together, these findings suggest that Cd has more sustainable and adverse health effects on the abandoned mine inhabitants, who are mostly aged. Therefore, continuous biomonitoring and risk assessment to environmental health risks are necessary for environmental pollution control and health promotion.

COVID-19 Outbreak and Its Association with Healthcare Workers' Emotional Stress: a Cross-Sectional Study.

BACKGROUND: The coronavirus disease 2019 (COVID-19) outbreak has exposed healthcare workers to extreme physical workloads and psychological challenges. Thus, we aimed to assess the immediate correlates of emotional stress and to identify which specific jobs, departments, and exposure types are risk factors for emotional stress in healthcare workers. METHODS: In this cross-sectional study conducted from April 2 to 10, 2020, university hospital workers were administered self-reported questionnaires that covered general characteristics and included the Patient Health Questionnaire, Generalized Anxiety Disorder scale, and a visual analog scale. At-risk groups for depression and anxiety were identified, and the odds ratios for depression and anxiety were analyzed after adjusting for age, gender, education, marital status, and duration of employment. RESULTS: The data of 1,003 participants were analyzed. Of these, 14.2% worked in wards for confirmed COVID-19 cases and 15.2% had had direct contact with these patients. Treating patients with COVID-19 was associated with depression and anxiety, while dealing with COVID-19 test samples was associated with depression. Exposure to random or unspecified patients was also associated with depression. Lastly, social rejection and other negative experiences were associated with depression and anxiety. CONCLUSION: The COVID-19 outbreak is correlated with healthcare workers' emotional stress, and specific types of jobs and duties involving close contact with these patients can be risk factors. Interestingly, even low-exposure groups reported significant depression and anxiety as a result of social stigma and uncertainty. Adequate and timely management measures for emotional stress are required for vulnerable and at-risk groups.

Blood cadmium concentration of residents living near abandoned metal mines in Korea.

The purpose of this study was to investigate demographic and lifestyle variables and blood cadmium concentrations in residents living near abandoned metal mines in Korea. Blood cadmium concentrations were measured in 15,161 subjects living around abandoned metal mines (exposed group, n = 14,464) and compared with those living in designated control areas (control group, n = 697). A questionnaire was provided to all subjects to determine age, gender, mine working history, times of residence, smoking habits and dietary water type. The geometric mean (95% confidence intervals) of blood cadmium concentration (1.25 [1.24-1.27] µg/L) in the exposed group was significantly higher than in the control group (1.17 [1.13-1.22] µg/L). Mean residence time and mine working history in the exposed group were significantly higher than in the control group. Blood cadmium concentrations increased with increasing age, and residence time in both groups, and blood cadmium concentrations were higher in current-smokers than in non-smokers in both groups. This study shows the geometric mean of blood cadmium concentration in abandoned mining areas are higher than in non-mining areas in the general adult Korean population.

Blood levels of cadmium and lead in residents near abandoned metal mine areas in Korea.

We analyzed national data on blood lead levels (BLL) and blood cadmium levels (BCL) in residents living near 38 abandoned metal mining areas (n = 5,682, 18-96 years old) in Korea that were collected by the first Health Effect Surveillance for Residents in Abandoned Metal mines (HESRAM) from 2008 to 2011. The geometric mean BCL and BLL were 1.60 µg/L (95 % CI = 1.57-1.62 µg/L) and 2.87 µg/dL (95 % CI = 2.84-2.90 µg/dL), respectively, notably higher than levels in the general population in Korea and other countries. We found significantly higher BLL and BCL levels in people living within 2 km of an abandoned metal mine (n = 3,165, BCL = 1.87 µg/L, BLL = 2.91 µg/dL) compared to people living more than 2 km away (n = 2,517, BCL = 1.31 µg/L, BLL = 2.82 µg/dL; P < 0.0001) and to the general population values reported in the literature.

Factors associated with musculoskeletal pain in professional dancers, including lapse period of group practice due to the COVID-19 outbreak: repeated-measures analysis.

BACKGROUND: This study investigated the prevalence and associated factors of musculoskeletal pain among professional dancers who experienced a lapse in group practice due to coronavirus disease 2019. METHODS: General characteristics, practice time, region of musculoskeletal pain due to injury using the visual numeric scale (VNS), and causative motion were surveyed among professional dancers. Pain of VNS 0 to 3 was categorized as "no or minor," 4 to 6 was categorized as "moderate," and 7 to 10 was categorized as "severe." The causal motions of musculoskeletal pain were analyzed according to body region. Factors other than motion associated with pain were also analyzed. RESULTS: In total, 368 participants were included. In the univariate analysis, age and practice time were positively associated with "moderate" pain. Practice time, dance experience, and postural accuracy were positively associated with "severe" pain, as was performing Korean traditional dance. In the multivariable analysis, practice time, group practice, and age were positively associated with pain of VNS 4 to 10, and practice time, group practice, and Korean traditional dance were positively associated with pain of VNS 7 to 10. CONCLUSION: Among the factors related to dancer training, practice time, group practice, and dance type affect the occurrence of pain.

Increase of blood mercury level with shark meat consumption: A repeated-measures study before and after Chuseok, Korean holiday.

Sharks are known to contain high levels of mercury in their meat. However, few studies have directly assessed the changes in mercury concentration in the human body according to shark meat intake. One hundred and ninety-seven participants that traditionally consume shark meat during the Chuseok holiday were recruited from two areas of Gyeongsangbuk-do, South Korea to examine their blood mercury level before and after the holiday season. Blood mercury levels were measured before and after the holiday season. Characteristics such as the consumption of shark meat, intake amount, and the effect on mercury concentration were assessed during the survey. Univariable and multivariable analysis (Linear Mixed Model) were done for assessing the association between shark meat consumption of holiday season and blood mercury level. Among the total participants, 83 consumed shark meat during holiday. In the univariable analysis, a significant increase in blood mercury levels before and after Chuseok was observed only for the group that consumed shark meat during holiday. The multivariable analysis (adjusted for identified confounders that affect both exposure and outcome considering repeated measurements) showed that consuming shark meat was significantly associated with increased blood mercury levels by 3.56 µg/L (95% confidence interval [CI], 2.64-4.67 µg/L). In the model considering the amount consumed as two group, the level of increase was 2.61 µg/L (95% CI, 1.63-3.58 µg/L) for those consuming <100 g, and 6.20 µg/L (95% CI, 4.77-7.62 µg/L) for those consuming ≥100 g compared to group without consuming shark meat. Considering amount consumed as continuous value, 0.02 µg/L (95% CI, 0.01-0.02 µg/L) of blood mercury increase was significantly associated with consuming 1 g. Consumption of shark meat significantly elevated blood mercury levels, exceeding commonly suggested reference concentrations in less than 2 weeks. These findings suggest the need for public health warnings and regulations regarding shark meat consumption.

The Impact of Aircraft Noise on the Cognitive Function of Elementary School Students in Korea.

Background: This study evaluated the effects of chronic exposure to aircraft noise on the cognitive functions of Korean elementary school students attending an elementary school around a military airfield and clarified the relationship between noise exposure and cognitive functions. Methods: Five schools with average weight equivalent continuous perceived noise levels (WECPNL) of ≥75 dB were selected from four regions in Korea. Each of these schools was matched with a non-exposed school. The Korean Intelligence Test Primary (KIT-P) was used to measure the scores of four subcategories and the intelligence quotient (IQ). The noise exposure groups were divided into high-exposure (WECPNL ≥ 80 dB) and medium-exposure (75 ≤ WECPNL < 80) groups. The period of exposure during the school year was collected. A linear mixed model, with matched pairs of schools, was used for statistical analysis. Results: In the multivariable linear mixed model adjusted by possible confounders, the reasoning score was significantly lower in the high-exposure group of students than in the no-exposure group. Other scores and IQ were lower in the noise exposure groups, although these were not statistically significant. The duration of exposure did not show a significant relationship with cognitive functions. Conclusion: Chronic exposure to noise from military airfields may influence the cognitive functions, thereby reducing the learning performance of Korean children.

Satisfaction of industrial health care managers regarding the work of industrial hygiene engineers: a cross-sectional study.

BACKGRUOUND: A group health service is a system that delegates workplace health management to an entrusted institution. There have been various studies on group health services to date, but recent changes, such as an increase in foreign workers, are rapidly changing industry characteristics. METHODS: Satisfaction was assessed using a 27-question survey distributed among 203 workplaces employing health professionals. The survey items consisted of general characteristics, comprehensive satisfaction, requirements for health professionals' work, and satisfaction with work environment management, ergonomic management, and healthcare management. Multiple regression and frequency analyses were performed. RESULTS: The comprehensive satisfaction was 4.08 points on average, out of 5. The comprehensive satisfaction of health professionals in the industry was positively correlated with each factor. Hazardous materials and chemical management (material safety data sheets, MSDSs) were the most common requirements. CONCLUSION: A low level of satisfaction with work environment management indicates high demand for healthcare management. The working environment should be improved by identifying characteristics of the workplace, examining harmful substances, inspecting equipment, and enhancing worker methods. The shorter the work experience of health professionals, the more dependent they are on group health services. The variables affecting comprehensive satisfaction were the period of work, healthcare management satisfaction, and work environment management satisfaction. Most of the requirements of health professionals in the workplace were practical improvement case presentations, MSDSs, and legal document management.

Cytotoxicity of dental self-curing resin for a temporary crown: an in vitro study.

BACKGROUND: Residual monomer tests using high-performance liquid chromatography and cytotoxicity tests were performed to analyze the effect on the oral mucosa of a self-curing resin for provisional crown production. METHODS: A cytotoxicity test was performed to confirm whether leaked residual monomers directly affected oral mucosal cells. The cytotoxicity of the liquid and solid resin polymers was measured using a water-soluble tetrazolium (WST) test and microplate reader. RESULTS: In the WST assay using a microplate reader, 73.4% of the cells survived at a concentration of 0.2% liquid resin polymer. The cytotoxicity of the liquid resin polymer was low at ≤0.2%. For the solid resins, when 100% of the eluate was used from each specimen, the average cell viability was 91.3% for the solid resin polymer and 100% for the hand-mixed self-curing resin, which is higher than the cell viability standard of 70%. The cytotoxicity of the solid resin polymer was low. CONCLUSION: Because the polymerization process of the self-curing resin may have harmful effects on the oral mucosa during the second and third stages, the solid resin should be manufactured indirectly using a dental model.

Rates and subsequent clinical course of fetal congenital anomalies detected by prenatal targeted ultrasonography of 137 cases over 5 years in a single institute: a retrospective observational study.

BACKGROUND: With the establishment of international guidelines and changes in insurance policies in Korea, the role of targeted ultrasonography has increased. This study aimed to identify the rates and clinical course of anomalies detected using prenatal targeted ultrasonography. METHODS: This study was a retrospective analysis of all pregnancies with targeted ultrasonography performed in a single secondary medical center over 5 years. RESULTS: Fetal anomalies were detected by targeted ultrasonography in 137 of the 8,147 cases (1.7%). The rates of anomalies were significantly higher in female fetuses (2.0% vs. 1.3%). In cases of female fetuses, the rate of anomalies was significantly higher in the advanced maternal age group (2.4% vs. 1.2%). In cases of male fetuses, the rate of anomalies was significantly higher in nulliparous (2.4% vs. 1.5%) and twin (5.7% vs. 1.9%) pregnancies. Pulmonary anomalies were significantly more common in the multiparity group (17.6% vs. 5.8%). Among the 137 cases, 17.5% terminated the pregnancy, 16.8% were diagnosed as normal after birth, and 42.3% were diagnosed with anomalies after birth or required follow-up. CONCLUSION: Through the first study on the rates and clinical course of anomalies detected by targeted ultrasonography at a single secondary center in Korea, we found that artificial abortions were performed at a high rate, even for relatively mild anomalies or anomalies with good prognosis. We suggest the necessity of a nationwide study to establish clinical guidelines based on actual incidences or prognoses.

Association between dental amalgam restoration and urine mercury concentrations among young women: a cross-sectional study.

BACKGROUND: The association between dental amalgam fillings and urine mercury concentrations was investigated in this study to assess the health risks associated with dental amalgams. METHODS: This cross-sectional study included 99 women in their 20s who visited the dental clinic in Daegu, Korea. The 99 participants were composed of 68 subjects who had dental amalgam fillings (exposure group) and 31 subjects who did not have dental amalgam fillings (nonexposure group). Oral examinations were conducted by a single dental hygienist, sociodemographic features were investigated as confounding variables, and urine mercury concentrations were measured using an automatic mercury analyzer. RESULTS: The mean±standard deviation of the urine mercury concentrations of the exposure and nonexposure groups were 1.50±1.78 µg/g creatinine and 0.53±0.63 µg/g creatinine, respectively. The exposure group showed significantly higher levels than the nonexposure group (p<0.01). The urine mercury concentration significantly increased with an increase in the number of teeth filled with amalgam, cavity surfaces involved, and number of defective amalgam fillings, and according to the latest exposure time (p<0.001). In the multiple regression analysis of amalgam-related factors and urine mercury concentrations after correction for confounding factors, the urine mercury concentration in the group with six or more amalgam-filled teeth, 11 or more cavity surfaces, and two or more defective amalgams was significantly higher than that in the nonexposure group (p<0.001). CONCLUSION: According to this study, exposure to dental amalgams was confirmed to significantly affect urine mercury concentrations.

Association of Blood Mercury Level with Liver Enzymes in Korean Adults: An Analysis of 2015-2017 Korean National Environmental Health Survey.

Increased liver enzymes as a result of exposure to mercury and their toxic effects are not well understood in Korea at the population level. The effect of blood mercury concentration on alanine aminotransferase (ALT) and aspartate aminotransferase (AST) was evaluated after adjusting for sex, age, obesity, alcohol consumption habit, smoking, and exercise parameters in 3712 adults. The risk of abnormal liver function was measured using a multiple logistic regression analysis. Blood mercury concentration was divided into quartiles, and liver enzyme levels were compared for each quartile. ALT and AST levels were 10-20% higher in the second, third, and fourth quartiles compared to the first quartile. The risk of liver dysfunction or elevated liver enzymes was significantly higher in the second, third, and fourth quartiles than in the first quartile. As blood mercury levels increased, liver enzymes and mercury-induced hepatotoxicity increased. The increase in liver enzymes caused by mercury was more pronounced in the low-mercury concentration range. To reduce the long-standing problem of abnormal liver enzymes and liver function in Korea and other similar settings, it is important to decrease exposure to mercury through effective implementation of specific health and environmental strategies.

Risk assessment of heavy metals in tuna from Japanese restaurants in the Republic of Korea.

Background: Studies on the risk of mercury (Hg) in Korean fishery products focus primarily on total Hg levels as opposed to methylmercury (MeHg) levels. None of the few studies on MeHg in tuna investigated tuna from Japanese restaurants. Few have evaluated lead (Pb), cadmium (Cd) and arsenic (As) in tuna. Thus, this study aimed to conduct a risk assessment by evaluating heavy metal concentrations in tuna from Japanese restaurants. Methods: Thirty-one tuna samples were collected from Japanese restaurants in the Republic of Korea. They were classified according to region and species. The concentration of heavy metals in the samples was analyzed using the Ministry of Food and Drug Safety Food Code method. The rate of exceedance of maximum residue levels (MRLs) and the risk compared to the provisional tolerable weekly intake (PTWI) set by the Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives (%PTWI) were evaluated for risk assessment. Results: The mean of MeHg, Pb, Cd and As concentrations were 0.56 ± 1.47 mg/kg, 33.95 ± 3.74 µg/kg, 14.25 ± 2.19 µg/kg and 1.46 ± 1.89 mg/kg, respectively. No sample exceeded the MRLs of Pb and Cd, but 9.7% of the samples exceeded the MRL of MeHg. The %PTWIs of MeHg, Pb, Cd and As were 4.2037, 0.0162, 0.0244 and 1.1627, respectively. The %PTWI of MeHg by age group and sex was highest among men aged 19-29 years (10.6494), followed by men aged 30-49 years (7.2458) and women aged 19-29 years (4.8307). Conclusions: We found that 3 out of 31 samples exceeded the MRL of MeHg. The %PTWI of MeHg showed significant differences based on age and sex, and the value was likely to exceed a safe level depending on individuals' eating behaviors. Therefore, improved risk management for MeHg is required.

Association of heavy metal complex exposure and neurobehavioral function of children.

Background: Exposure to heavy metals is a public health concern worldwide. Previous studies on the association between heavy metal exposure and neurobehavioral functions in children have focused on single exposures and clinical manifestations. However, the present study evaluated the effects of heavy metal complex exposure on subclinical neurobehavioral function using a Korean Computerized Neurobehavior Test (KCNT). Methods: Urinary mercury, lead, cadmium analyses as well as symbol digit substitution (SDS) and choice reaction time (CRT) tests of the KCNT were conducted in children aged between 10 and 12 years. Reaction time and urinary heavy metal levels were analyzed using partial correlation, linear regression, Bayesian kernel machine regression (BKMR), the weighted quantile sum (WQS) regression and quantile G-computation analysis. Results: Participants of 203 SDS tests and 198 CRT tests were analyzed, excluding poor cooperation and inappropriate urine sample. Partial correlation analysis revealed no association between neurobehavioral function and exposure to individual heavy metals. The result of multiple linear regression shows significant positive association between urinary lead, mercury, and CRT. BMKR, WQS regression and quantile G-computation analysis showed a statistically significant positive association between complex urinary heavy metal concentrations, especially lead and mercury, and reaction time. Conclusions: Assuming complex exposures, urinary heavy metal concentrations showed a statistically significant positive association with CRT. These results suggest that heavy metal complex exposure during childhood should be evaluated and managed strictly.

Association between environmental tobacco smoke exposure of children and parental socioeconomic status: a cross-sectional study in Korea.

INTRODUCTION: It has been reported that most environmental tobacco smoke (ETS) exposure of children occurs at home, and lower parental socioeconomic status (SES) increases the risk of this exposure. We estimated the independent and interactive effects of parental SES and residential area SES on ETS exposure of children at home. METHODS: We evaluated whether ETS exposure was associated with parental SES by entering data from 7,059 school-aged children in Korea into fixed effects models. The empirical model, including the interaction variable of the level of deprivation of each residential area, was fitted with parental SES. RESULTS: After adjustment for possible confounding variables, low paternal education (odds ratio [OR], 1.81; 95% CI, 1.30-2.54) and highly deprived areas (OR, 1.34; 95% CI, 1.06-1.69) were significantly associated with the ETS exposure of children, especially among children whose fathers had <12 years of education and lived in the most deprived area (OR, 2.04; 95% CI, 1.04-4.02). CONCLUSIONS: Our findings suggest that the SES of residential areas may influence the ETS exposure of children directly, as well as interactively with parental SES, in Korea. Findings from this study will help inform policy decision makers that intervention to promote smoking cessation should consider not only the SES of individuals but also that of residential areas.

Effect of environmental tobacco smoke on atopic dermatitis among children in Korea.

The prevalence of atopic dermatitis is increasing in many countries. Several factors are known to be associated with childhood atopic dermatitis. Environmental tobacco smoke (ETS) is one of the most common indoor pollutants, and children are more vulnerable to ETS exposure than adults are. In this study, the possible association of ETS with atopic dermatitis was evaluated in 7030 individuals aged 6-13 years who participated in the Children's Health and Environment Research study. In addition, predictive factors, such as the allergic history of the parents, children's immunoglobulin E levels and children's history of rhinitis and its association with dermatitis, were assessed. After adjustment for possible confounding variables, atopic dermatitis was found to be highly correlated with ETS, especially among children whose mothers had smoked during pregnancy and/or in the first year after birth (OR=2.06, 95% CI: 1.01-4.22). In conclusion, our results show that childhood exposure to ETS is a major risk factor for atopic dermatitis.

Dental composite fillings and bisphenol A among children: a survey in South Korea.

AIMS: Bisphenol A (BPA)-based dental composites have commonly been used to fill dental cavities or seal pits and fissures on teeth. However, epidemiological evidence with regard to the BPA exposure from dental composites among children has rarely been reported. This study investigated whether there is a relationship between the BPA concentration in urine and the presence of composite restorations and sealants among South Korean children. METHODS: Oral examinations and urine sample analyses were conducted on a total of 495 children aged 8-9 years. We classified the participants into four groups by the number of resin composites and sealant surfaces (0, 1-5, 6-10 and 11+). RESULTS: BPA concentrations in urine were higher in children with 11 or more surfaces restored with sealants and resin composites than in those with zero restored surfaces, although no difference was seen in the group with 1-10 surfaces. After adjusting for gender and age, the urinary BPA concentration in children with 11 or more resin composite surfaces was 2.67 µg/g creatinine, which was higher than the concentration found in those with no filling surfaces (P < 0.01). CONCLUSIONS: Having many dental composite filling surfaces on teeth may increase the urinary BPA concentration in children.

Blood lead levels of residents living around 350 abandoned metal mines in Korea.

In 2007, as part of the control and prevention of environmental contamination threatening public health, the Korean Ministry of Environment planned to implement a national biomonitoring survey of three metals: lead, cadmium, and mercury in the blood of residents living near 350 abandoned metal mines known to be contaminated and as possible threats to the health of inhabitants. Thus, we investigated demographic and lifestyle variables and blood lead levels in residents living around the mines and compared them against those of control subjects. We measured the blood lead concentrations in 14,849 subjects (14,132 from nearby the 350 abandoned metal mines and 717 subjects from eight control areas). A questionnaire was provided to all subjects to determine gender, age, mining experience, period of time living in the vicinity of mines, smoking status, and personal perception of abandoned mines as a health risk. The geometric means (95% confidence intervals) of the blood lead levels of residents living around the abandoned metal mines and control areas were 3.017 (2.996-3.037 µg/dL) [female, 2.797 µg/dL (2.771-2.822 µg/dL); male, 3.330 µg/dL (3.298-3.363 µg/dL)] and 2.757 (2.677-2.837 µg/dL) [female, 2.604 µg/dL (2.506-2.700 µg/dL); male, 2.993 µg/dL (2.859-3.126 µg/dL)], respectively. Among residents of the mining areas, nonsmokers and residents who had no mining experience showed significantly lower mean blood lead levels than did smokers, past smokers, and those with mining experience. The mean blood lead concentrations of residents who expressed some concern about the abandoned mines were significantly higher than those of residents without concerns. The mean blood lead concentration of residents living around the abandoned mines was significantly higher than that of residents living in control areas as well as that of the general adult Korean population. We also confirmed that smoking is an important variable to consider, as it increases blood lead concentration.

Preventive Measures Against COVID-19 in Small- and Mid-sized Enterprises from an Early Stage of the Epidemic in Daegu and Gyeongsangbuk-do.

Background: In the early stage of the coronavirus disease 2019 (COVID-19) epidemic, small- and mid-sized enterprises (SMEs) may be an important transmission consideration. The study aimed to identify the pattern of COVID-19 prevention measures during the outbreaks in Daegu and Gyeongsangbuk-do at the early stage of COVID-19. Moreover, we investigated whether SME size and past experiences affected the preventive measures implemented in the region. Methods: A survey detailing the general characteristics and implementation of 12 preventive activities was conducted in 122 SMEs in Daegu and Gyeongsangbuk-do. The survey was analyzed by size and operation period. Results: The study subjects consisted of 53 (43.4%) workplaces with 1-5 employees, 50 (40.9%) workplaces with 6-30 employees, and 19 (15.6%) workplaces with 31-49 employees. The lowest three items among those surveyed were 'symptomatic workers to stay home for 3-4 days' (17.2%), 'work remotely' (18.9%), and 'video meetings' (20.5%). There were significant differences in the rate of several preventive measures implemented. The larger sized SMEs, the higher the number of implementations (p < 0.01). The operation period had no significant relationship with the implementation of preventive measures. The same pattern was observed in multiple generalized linear regression with covariate adjustment. Conclusion: Preventive measures among SMEs with fewer than 50 employees were identified. Even within SMEs, a gap in preventive measures according to size was confirmed. To prevent the spread of infection and protect workers' right to health, different support for different sized SMEs is necessary.