Chul-Gab Lee

Association of ozone exposure with asthma, allergic rhinitis, and allergic sensitization

BACKGROUND Children are vulnerable to air pollution, which is known to be related to the recent increasing trend of allergic disease. OBJECTIVE To investigate the effects of air pollution on respiratory allergic diseases in school children. METHODS A prospective survey of parental responses to International Study of Asthma and Allergies in Childhood questionnaires, together with allergy evaluation, was conducted in 1743 school children selected from metropolitan cities and industrial areas during a 2-year period. Individual exposure to air pollution was estimated by using a geometric information system with the 5-year mean concentration of air pollutants. RESULTS A total of 1,340 children (male:female ratio, 51.4:48.6) with a mean (SD) age of 6.84 (0.51) years were included in the analysis. Each child underwent allergy evaluation at the time of enrollment and at a 2-year follow-up. After 2 years, the 12-month prevalence of wheezing was significantly decreased, whereas the lifetime prevalence of allergic rhinitis showed a significant increase. Ozone exposure was significantly associated with the 12-month prevalence of wheeze (odds ratio per 5 ppb, 1.372; 95% confidence interval, 1.016-1.852). Ozone was also associated with allergic rhinitis in children who reside in industrial areas. In addition, significant positive associations between ozone and the rate of newly developed sensitization to outdoor allergen were found (P for trend = .007). CONCLUSION Exposure to ozone was associated with current wheeze and allergic rhinitis. An increased rate of newly developed sensitization to outdoor allergen by ozone may explain the association.

Air pollution interacts with past episodes of bronchiolitis in the development of asthma.

Exposure to ambient air pollution and bronchiolitis are risk factors for asthma. The aim of this study was to investigate the effect of air pollution on the development of asthma in children with past episodes of bronchiolitis.

Representative levels of blood lead, mercury, and urinary cadmium in youth: Korean Environmental Health Survey in Children and Adolescents (KorEHS-C), 2012–2014

BACKGROUND This study examined levels of blood lead and mercury, and urinary cadmium, and associated sociodemographic factors in 3-18 year-old Korean children and adolescents. MATERIALS AND METHODS We used the nationally representative Korean Environmental Health Survey in Children and Adolescents data for 2012-2014 and identified 2388 children and adolescents aged 3-18 years. The median and 95th percentile exposure biomarker levels with 95% confidence intervals (CIs) were calculated. Multivariate regression analyses were performed on log transformed exposure biomarker levels adjusted for age, sex, area, household income, and fathers education level. The median exposure biomarker levels were compared with data from Germany, the US, and Canada, as well as the levels of Korean children measured at different times. RESULTS The median levels of blood lead and mercury, as well as urinary cadmium were 1.23μg/dL, 1.80μg/L, and 0.40μg/L (95% CIs, 1.21-1.25, 1.77-1.83, and 0.39-0.41, respectively). The blood lead levels were significantly higher in boys and younger children (p<0.0001) and children with less educated fathers (p=0.004) after adjusting for covariates. Urinary cadmium level increased with age (p<0.0001). The median levels of blood mercury and urinary cadmium were much higher in Korean children and adolescents than those in their peers in Germany, the US, and Canada. Blood lead levels tended to decrease with increasing age and divergence between the sexes, particularly in the early teen years. Median levels of blood lead and urinary cadmium decreased since 2010. CONCLUSION Sociodemographic factors, including age, sex, and fathers education level were associated with environmental exposure to heavy metals in Korean children and adolescents. These biomonitoring data are valuable for ongoing surveillance of environmental exposure in this vulnerable population.

Changes in Balance Ability and Muscle Thickness of the Transverse Abdominis and Multifidus of Elderly Females after Eight Weeks of the Lumbar Stabilization Exercise

이 연구는 여성노인의 낙상 예방을 위하여 요부안정화운동을 실시하고 요부 등척성 근력, 복횡근과 다열근의 근두께, 자세안정성의 변화를 측정하였다. 대상자는 광주광역시에 소재한 요양원에서 여성노인 21명을 대상으로 8주간 운동 후 요부 등척성 근력, 복횡근과 다열근의 근두께, 자세안정성을 비교하였다. 요부 등척성 근력은 페가수스 근력 측정장치(3D Pegasus system, Germany), 복횡근과 다열근의 근두께는 초음파영상 계측장치(Sonoace 6000C, Korea), 자세안정성은 BBS 균형측정장치(Biodex Balance System SD, USA)로 측정하고 분석하였다. 요부 등척성 근력 중 굴곡, 신전, 좌회전과 복횡근 이완(횡)두께는 운동 전보다 운동 후에 통계학적으로 유의하게 증가하였으며, 자세안정성변화에서 전체 좌우 전후균형지수 모두 운동 후 통계학적으로 유의하게 감소하였다. 요부안정화운동이 근력 및 자세안정성에 영향을 미쳐 여성노인의 낙상 예방에 효과적이다 라는 결론을 얻었다. 【This study was conducted to examine the effects of the lumbar stabilization exercise (LSE) on fall prevention in elderly females (n = 21) by measuring changes in the isometric strength, multifidus, transverse abdominis muscle thickness, and posture stability index. The strength of isometric contraction was measured by the 3-D Pegasus system ; the thickness of the multifidus and transverse abdominis were measured by using Sonoace 6000C, and the posture stability index was measured using a computerized Biodex Balance System SD apparatus analysis. These results lead us to the conclusion that flexion and extension, left rotation on strength of isometric contraction, and thickness of the transverse abdominis (when released) statically increased. Overall, the anterior/posterior and medial/lateral elements in the posture stability index statically decreased, Consequently, the LSE should the prevent falls in elderly females.】

Factors Related to the Prevalence of Respiratory Symptoms in Workers in a Petrochemical Complex

Factors Related to the Prevalence of Respiratory Symptoms in Workers in a Petrochemical Complex: Jong Park, et al. Department of Preventive Medicine, College of Medicine, Chosun University, Korea—This study was performed to evaluate the prevalence of respiratory symptoms in workers in a petrochemical complex and to elucidate the relationship between the prevalence and work‐related factors. A questionnaire was distributed to 5,983 male workers working in a petrochemical complex. As for the respiratory symptoms, cough was present in 2.4%, phlegm in 8.1%, wheezing in 2.8% and shortness of breath in 4.7% of the workers. The factors significantly related to respiratory symptoms were smoking history, wearing of protective devices, handling of substances toxic to the respiratory system, and history of atopy or respiratory disease (p<0.05). The substances toxic to the respiratory system were divided into 4 types, ie., dusts, solvents, metals, and vapors. When the analysis was performed to evaluate the effects of exposure to substance type on respiratory symptoms, the odds ratio of cough was 1.96 times higher in those workers exposed to dusts compared with those not exposed, 2.28 times for exposure to metals, 1.52 times for solvents, and 1.55 times for vapors, all showing significant differences (p<0.05). For phlegm, the odds ratio was 1.08 times higher in those workers exposed to dusts compared with those not exposed, 1.94 times for exposure to metals, 1.70 times for organic solvents, and 1.85 for vapors (p<0.05). For wheezing, the odds ratio was 2.38 times for exposure to dusts; for shortness of breath, it was 2.42 times for exposure to dusts, 2.89 times for metals, 2.10 times for organic solvents, and 2.14 times for vapors, all showing significant differences (p<0.05). In conclusion, work‐related factors significantly affected the respiratory symptoms in workers working in the petrochemical complex. Especially, these respiratory symptoms were significantly related to exposure to toxic substances and the wearing of protective devices. Thus, safety education and management are needed for these workers.

Association of current phthalate exposure with neurobehavioral development in a national sample.

BACKGROUND Previous studies have indicated that phthalate exposure may influence the development of children, but the current data are limited, and controversy remains regarding the sex-specific and age-specific effects of phthalate exposure. METHODS We investigated the sex- and age-specific associations of current phthalate exposure with neurobehavioral development scores in a nationally representative sample of 6-18-year-olds participating in the Korean Environmental Health Survey in Children and Adolescents (KorEHS-C). Neurobehavioral development was assessed using the Korean Child Behavior Checklist (CBCL, N=1723) and the Korean Attention Deficit Hyperactivity Disorder Rating Scale (ARS, N=867). We measured the concentrations of phthalate metabolites in urine samples using high-performance liquid chromatography tandem mass spectrometry. The associations between urine phthalate metabolite concentrations and neurobehavioral development were examined by survey regression analysis for complex sampling and penalized regression splines using a generalized additive model. RESULTS Survey regression analysis revealed that a higher mono-n-butyl phthalate (MnBP) level was associated with social (β=0.60; 95% confidence interval=0.15-1.05), thought (0.55; 0.08-1.03), and attention (0.68; 0.21-1.14) problems on the CBCL. A significant association was found between the MnBP level and the ARS hyperactivity subscale score (0.42; 0.05-0.58). Higher levels of MnBP (0.87; 0.20-1.54), mono-2-ethyl-5-oxohexyl phthalate (MEOHP, 0.61; 0.11-1.11) and mono-2-ethyl-5-hydroxyhexyl phthalate (MEHHP, 0.51; 0.04-0.97) were associated with an increase in thought problems among the girls. Among the younger children aged 6-11 years, significant positive associations between the MnBP (0.71; 0.09-1.33), MECPP (0.74, 0.14-1.34), MEOHP (0.65; 0.10-1.20), and MEHHP (0.71; 0.21-1.21) levels and social problems and between the MnBP (1.11; 0.37-1.84), MEOHP (0.64; 0.13-1.15), and MEHHP (0.66; 0.18-1.14) levels and attention problems were observed. The penalized regression splines for the age-specific relationships between the urinary MnBP, MEOHP, and MEHHP levels and social and attention problems exhibited positive supralinear relationships with downward curvature in the 6-11 year age group. In contrast, the score for social problems exhibited nearly linear relationships with these levels in the 12-18 year age group. CONCLUSIONS In this national sample, increased phthalate exposure exhibited supralinear associations with social, thought and attention problems in children aged 6-11 years, who showed greater vulnerability to phthalate exposure. The results highlight the need for the environmental regulation of phthalate exposure in younger children, even at low dosages.

Biomechanical Analysis on Locomotion with Lower Extremity Supporter

The purpose of this study was to analyze the effects of the use of the lower extremity supporter to ground reaction force(GRF) & EMG in women. Five women participated in the experiment conducted in the study(age: yrs, weight: kg, lower extremity height: cm, knee height: cm). The Ground reaction force was measured by AMTI ORG-6 and the Muscle activity of the lower extremity was measured by an 8-channel surface EMG system(Noraxon Myoresearch, USA, 1000Hz). We statistically compared muscle activity and ground reaction force with and without the lower-extremity supporter by one-way repeated ANOVA. The results were as follows. First, the use of the lower extremity supporter affects the ground reaction force along the anterior-posterior axis(Y). Second, the vertical(Z-axis) reaction force on the upper part of the lower extremity supporter increase because of the difference between the interval of vertical movement. Third, the muscle activity of the lateral gastrocnemius and rectus femoris was higher in the upper part of the lower extremity supporter. Further research for example, on a comparative analysis of joint moments, the effects of direct stressor on joints. and the relationship between muscle activity and joint movement, is necessary for a better understanding of the effects of the lower-extremity supporter.

Environmental Tobacco Smoke Exposure at Home and High-Sensitivity C-Reactive Protein Levels in Three-to-Five-Year-Old Children

Exposure to harmful environmental factors is particularly detrimental to younger children. We investigated the relationship between environmental tobacco smoke (ETS) exposure in pre-schoolers at home and the level of high-sensitivity C-reactive protein (hs-CRP), a predictive factor for cardiovascular disease. This study was conducted in 2014 and was based on the data of preschool children from the Korean Environmental Health Survey in Children and Adolescents (2012 to 2014), a nationally representative sample. Of 577 children, aged three to five years, 482 were eventually selected for the analysis after excluding those with missing variables, or whose hs-CRP level exceeded the reference value. The proportion of pre-school children exposed to ETS at home was 14.8%. The odd ratios (OR)s of hs-CRP > 1mg/L were 4.90 (95% Confidence Interval (CI) = 1.04–23.17) and 11.66 (95% CI = 1.90–71.65) in the groups exposed to ETS 3–4 times and ≥5 times daily, respectively, compared to the non-exposed group. The risk of elevated levels of hs-CRP showed an increasing trend proportionally to the increase in ETS exposure frequency (p for trend = 0.03). Anti-smoking educational programs for parents and guardians may be helpful to reduce ETS exposure at home.

Analysis of Biomechanical Changes According to Mechanical Alignment of the Lower Limbs when Gait with a Material Handling

Objective : Walking with a Material handling is an activity frequently undertaken by agricultural workers in Korea, due to the nature of their work. This study aimed to investigate differences in biomechanical variables according to the mechanical alignment of the lower limbs when walking with a heavy load, and to use this as basic data in the design of various working environments to reduce the skeletomuscular burden on the knee joint. Method : The study subjects comprised of 22 right-foot dominant adult men and women aged between 20 and 23 years. The subjects were divided into a varus or valgus group according to the mechanical alignment of the lower limb by using radiographic findings. The subjects walked without any load and with a load of 10%, 20%, or 30% of their body weight held in front of them. The Kwon3d XP program was used to calculate biomechanical variables. Results : The flexion/extension moment of the knee joint showed a decreasing trend with increased load, irrespective of the mechanical alignment of the lower limb, while the varus group did not show normal compensatory action when supported by one leg at the point of maximum vertical ground reaction force. In addition, in terms of the time taken, subjects showed no difficulties in one-foot support time up to 20%/BW, but at 30%/BW, despite individual differences, there was an increase in single limb. The increased load resulted in a decrease in the ratio of standing phase to ensure physical stability. The valgus group showed a trend of increasing the stability of their center of mass with increasing load, through higher braking power in the early standing phase. Conclusion : In conclusion, although there was no statistical difference in biomechanical variables according to the mechanical alignment of the lower limbs, the varus group showed a more irregular walking pattern with a Material handling than the valgus group, partially proving the association between lower limb alignment and walking with a Material handling.

Analysis on Biomechanical Differences Depending on Changes in Postures during Farm Work

Objective: This study looks into biomechanical variables occurring when one moves in a sitting posture, and presents objective references to make improvements in work environments of farm workers. Background: The farmers have more common musculoskeletal disorders compared to other professions, because they are much more exposed to biomechanical risk factors. The sitting posture that is the representative form of the squatted, can cause typical knee joint diseases, such as osteoarthritis or patellofemoral pain syndrome of the knee joint. Therefore, a quantitative study of knee load upon the movement in a squatting posture is required. Method: In order to proceed with its investigation, the study examined movements in a sitting posture with and without a lower body supporter through a threedimensional image analysis and by using Surface EMG. The study compared and analyzed the average muscle activity and the maximum muscle activity as well. Results: Every movement in a sitting posture is related to loads onto the knee joints and, when the farm workers move to sides, the study observed a high level of bowlegged moment. The study also noticed differences in muscle activity of medial gastrocnemius with and without the lower body supporter. Conclusion and Application: The study argues that what has been discussed so far is evidence to prove how the farm working environments should be improved in consideration of these movements observed when the farm workers move in a sitting posture.