Sang-Gil Lee

The relationship between low-level benzene exposure and blood cell counts in Korean workers

Objectives Benzene is a well-known haematological toxin causing aplastic anaemia and leukaemia. Some recent studies have shown that low-level benzene exposure (<1 ppm) disturbs the haematopoietic system. However, other studies showed inconsistent results. The aim of the present study was to examine the relationship between low-level benzene exposure and blood cell counts in Korean workers. Methods Blood cell counts of benzene-exposed workers were extracted from a nationwide Special Health Examination Database from 2000 to 2008. If a worker did not take a blood test for benzene between 2000 and 2004, the worker was selected for analysis. In total, 8679 personal air benzene measurements were extracted from the nationwide Workplace Environment Measurement Database from 2004 to 2008. Mean benzene levels were calculated and assigned to benzene-exposed workers using various combinations of factory/industry/process codes. Mixed-effects models were used to examine dose-related associations between benzene levels and white blood cell (WBC), red blood cell (RBC), platelet, neutrophil and lymphocyte counts. Results In total, 21 140 blood samples were tested from 10 702 workers between 2005 and 2008; 40% of the workers had repeated blood tests (average, 3.4 times). RBC counts in male workers showed a significant negative association with low-level benzene exposure. WBC, platelet, neutrophil and lymphocyte counts did not show a consistent association with low-level benzene exposure. Conclusions Our findings support the potential haematotoxicity of low-level benzene exposure (<1 ppm). A longitudinal study with direct benzene measurements for exposed workers is needed to confirm the toxicity of low-level benzene exposure.

Long Working Hours and Emotional Well-Being in Korean Manufacturing Industry Employees

ObjectivesKorea is well known for its long work hours amongst employees. Because workers of the manufacturing industry are constantly exposed to extended work hours, this study was based on how long work hours affect their emotional well-being.MethodsThe analysis was done using the secondary Korean Working Condition Survey (KWCS). Long work hours were defined to be more than 48 hours, and they were subcategorized into units of 52 hours and 60 hours. Based on the WHO (five) well-being index, emotional state was subdivided into three groups - reference group, low-mood group, and possible depression group- where 28 points and 50 points were division points, and two groups were compared at a time. Association between long work hours and emotional state was analyzed using binary and multinomial logistic regression analysis.ResultsWorking for extended working hours in the manufacturing industry showed a statistically significant increase (t test p < 0.001) in trend among the possible depression group when compared to the reference group and the low-mood group. When demographical characteristics, health behaviors, socioeconomic state, and work-related characteristics were fixed as controlled variables, as work hours increased the odds ratio of the possible depression group increased compared to the reference group, and especially the odds ratio was 2.73 times increased for work hours between 48–52 and 4.09 times increased for 60 hours or more and both were statistically significant. In comparing the low-mood group and possible depression group, as work hours increased the odds ratio increased to 1.73, 2.39, and 4.16 times, and all work hours from working 48–52 hours, 53–60 hours, and 60 hours or more were statistically significant. Multinomial logistic regression analysis also showed that among the reference group and possible group, the possible depression group was statistically significant as odds ratio increased to 2.94 times in working 53–60 hours, and 4.35 times in 60 hours or more.ConclusionsLong work hours have an adverse effect on emotional well-being. A more diversified research towards variables that affect long work hours and emotional well-being and how they interact with each other and their relationship to overall health is imperative.

Interstitial lung disorders in the indium workers of Korea: An update study for the relationship with biological exposure indices

BACKGROUND Korea is one of the highest indium-consuming countries worldwide. The present study aims to determine the relationship between interstitial lung disorders and indium exposure in Korea. METHODS In 50 indium workers from seven plants, the effect of serum indium on the lungs was determined using laboratory tests, spirometry, and high-resolution computed tomography (HRCT). RESULTS Higher serum indium and Krebs von den Lungen-6 (KL-6) levels were associated with HRCT-detected interstitial lung changes. Workers with high serum indium levels (≥3 µg/L) had longer exposure durations and a higher prevalence of HRCT-detected interstitial lung changes. KL-6 and surfactant protein-D (SP-D) levels were significantly higher in the highest serum indium quartile than the lowest quartile. Significant dose-effect relationships existed between serum indium levels and KL-6, SP-D levels and the prevalence of HRCT-detected interstitial lung changes. CONCLUSIONS Workforce medical surveillance should be established to prevent indium-induced interstitial lung disease in Korea.

Work-relatedness of lung cancer by smoking and histologic type in Korea

ObjectivesThis study investigated the distribution of causative agents related to occupational lung cancer, their relationships with work, and associations between work-relatedness and the histologic type of lung cancer.MethodsWe used data from the occupational surveillance system in Korea in 2013. In addition, data from 1,404 participants diagnosed with lung cancer were collected through interviews. We included the patients’ longest-held job in the analysis. Work-relatedness was categorized as “definite,” “probable,” “possible,” “suspicious,” “none,” or “undetermined.”ResultsAmong the subjects, 69.3% were men and 30.7% were women. Regarding smoking status, current smokers were the most prevalent (35.5%), followed by non-smokers (32.3%), ex-smokers (32.2%). Regarding the causative agents of lung cancer, asbestos (1.0%) and crystalline silica (0.9%) were the most common in definite work-related cases, while non-arsenical insecticide (2.8%) was the most common in probable cases followed by diesel engine exhaust (1.9%) and asbestos (1.0%). Regarding histologic type, adenocarcinoma was the most common (41.7%), followed by squamous cell carcinoma (21.2%). Among current smokers, squamous cell carcinoma was the most common among definite and probable cases (13.4%), while non-small cell lung cancer was the least common (7.1%). Among non-smokers, squamous cell carcinoma was the most common (21.4%), while the least common was adenocarcinoma (1.6%).ConclusionsApproximately, 9.5% of all lung cancer cases in Korea are occupational-related lung cancer. Well-known substances associated with lung cancer, such as crystalline silica, asbestos, and diesel engine exhaust, are of particular concern. However, the histologic types of lung cancer related to smoking were inconsistent with previous studies when work-relatedness was taken into account. Future studies are required to clarify the incidence of occupational lung cancer in agricultural workers exposed to non-arsenical insecticides and the associations between work-relatedness and the histologic type of lung cancer.

1132 Estimation of lead exposure prevalence in korean population through combining multiple experts’ judgment based on objective data sources

Objectives Estimation of exposure prevalences of carcinogens is important for preventing occupational cancers. For developing Korean CAREX (CARcinogen EXposure) which is a carcinogen surveillance system employed in many countries, as an exemplary carcinogen, we estimated lead exposure prevalences in Korean working population. Methods We used three nationwide data sources to retrieve objective default estimates of lead exposure prevalence across industries: the work-environment monitoring database (WEMD), the special health examination database (SHED), and the Work Environment Condition Survey (WECS). Furthermore, we surveyed experts for their judgment about lead exposure prevalence across industries after reviewing the default estimates computed from aforementioned three exposure databases. We developed various estimation methods combining experts’ judgment, and then compared with each other. The 2010 Census was used as the reference population to estimate the number of lead-exposed workers for the 228 industries through multiplying the exposure prevalence with the number of workers in each industry. Results Default estimates of exposure prevalence for 228 industries were calculated using the WEMD and SHED collected between 2009–2011, and the 2009 WECS. A total of 52 experts who have 20 or more experience in industrial hygiene practice participated in the study and provided their judgment on the lead exposure prevalences as a number for the 228 industries. Among various estimation methods, the median values of experts’ responses were selected for our estimates of lead exposure prevalence in each industry. As a result, a total of 129,247 Korean workers was estimated to be exposed to lead in the year of 2010. Conclusions We developed a method estimating exposure prevalences combining experts’ judgment based on objective databases. Our effort for estimating the exposure prevalences of CAREX may introduce an unbiased approach to the development process accounting for uncertainty of exposure.

1131 Combining lead exposure measurements and experts’ opinion through a bayesian framework

Objectives CAREX (CARcinogen EXposure) is a carcinogen surveillance system employed in many countries. To initiate Korean CAREX, we focused on estimating the exposure intensity of lead across industries, which is a suspected carcinogen. Methods We extracted airborne lead measurements from the work environment measurement database (WEMD) which is the Korean nationwide measurement database. In addition, we elicited the experts’ opinion about lead exposure intensity across industries by conducting a questionnaire. Experts provided estimates of lead exposure levels as the boundary of the 5th and 95th percentiles. We assumed that experts provided their estimates based on the assumption of log-normal distributions of exposure. First, for each industry, estimates of log-transformed geometric means (logGM) and log-transformed geometric standard deviations (logGSD) were extracted from the experts’ responses, followed by combining them to quantify the experts’ prior Normal-Inverse-Gamma prior distribution. Then, the corresponding logGM and logGSD from lead measurement data for each industry were updated with the experts’ prior distribution through a Bayesian framework, yielding posterior distributions of logGM and logGSD. Results WEMD contains 83 035 airborne lead measurements collected between 2002–2007. Total 17 occupational hygiene professionals with more than 20 year experience provided lead exposure estimates. In industries where measurement data is abundant, the measurement data dominate the posterior exposure estimates, while in industries with a limited number of measurements, experts’ opinion played an important role in determining posterior exposure estimates. For example, rubber manufacturing industry with 246 measurements (GM 1.72; GSD 1.94) and 6 experts’ responses (GM 0.79; GSD 6.73) showed posterior exposure estimates of GM 1.60 and GSD 2.34. Conclusions Our method of estimating the exposure intensity of CAREX may introduce an unbiased approach to the development process by utilising both prior knowledge of experts and measurement data simultaneously. In addition, it will supply a framework for future updates.

0088 Characteristics of non-hodgkin’s lymphoma patients among a cohort of semiconductor-manufacturing workers

Objective The Occupational Safety and Health Research Institute (OSHRI) established a cohort consisting of workers in six semiconductor-manufacturing companies to determine cancer incidence. The data gathered until 2014 revealed that 43 non-Hodgkin’s lymphoma (NHL) cases occurred. This study aimed to identify the characteristics of these cases. Methods In 2008, OSHRI established a cohort based on company personnel records and national cancer registration data that could be obtained from Statistics Korea on former and current workers of six semiconductor-manufacturing factories in South Korea since 1998. This study analysed the characteristics of NHL cases that occurred in this cohort. Results In the cohort, 43 NHL cases occurred. Of those cases, 23 were men and 20 were women. The highest incidence of 20 cases occurred in the workers in their 30 s. The years 1995–1999 and 2000–2004 were the most common time periods for entry into the company with 11 and 10 cases, respectively. The types of occupations included: 33 manufacturing workers, 7 non-manufacturing workers, and 3 who could not be precisely categorised. Conclusion Although NHL as an illness that is known to occur at a relatively old age, the prevalence of NHL among former and current semiconductor workers, occurring at a younger working age, may suggest causality based on occupation. As such, identifying their demographic characteristics is a necessary step towards identifying the occupational hazards in the semiconductor industry and the risk factors for development of NHL.

0406 Analysis of infectious disease prevalence among semiconductor manufacturing workers with non-hodgkin’s lymphoma

Introduction The Occupational Safety and Health Research Institute (OSHRI) established a cohort of former and current workers in six semiconductor-manufacturing companies in South Korea, to determine the incidence of occupational cancer. This study compared the prevalence and incidence of general illnesses between patients with non-Hodgkin lymphoma (NHL) and a control group. Research Methods After identifying 43 workers with NHL, OSHRI established a sex- and age-matched control group. The NHL cohort and control groups were compared for the prevalence of infectious diseases before and after diagnosis. The prevalence of infectious diseases was based on diagnostic data collected from National Health Insurance information. Disease names were determined by the ICD-10 disease code. Outcomes Prior to the diagnosis of NHL, there was no significant difference in the prevalence of bacterial and viral diseases between the groups. However, following the diagnosis of NHL, the prevalence rates of viral and bacterial infections were significantly higher in the NHL group. Significant differences were found in the prevalence of herpes zoster, cytomegalovirus, and tuberculosis. Conclusion Prior to the diagnosis of NHL, there were no significant underlying diseases in the NHL cohort group when compared to the control group. Therefore, we concluded there is no relationship between underlying infectious disease and NHL development. However, the probability of contracting opportunistic infections was higher in the NHL group after diagnosis. Presumably, cancer progression and treatment may cause opportunistic infections. Further evaluation is necessary to support this result.

P279 A case of azoospermia in a non-destructive testing (NDT) worker exposed to ionising radiation

Many workers are exposed to ionising radiation and it has various detrimental health effects. Those are categorised into stochastic effects and deterministic effects. We represent a case of an azoospermic patient who exposed to ionising radiation and affected by deterministic effects for permanent infertility. He had been worked for a NDT company for six years and mainly performed the radiography testing (RT). He took RT images from 300 to 1,000 per day with barely equipped with protectives. After work, he felt nauseated, fatigue and got a headache from time to time. In addition, he could not conceive a baby even though he tried for eight years with normal intercourses and no contraceptives. He visited urology department and diagnosed with irreversible azoospermia and there were no evidence that he was congenitally infertile; He had a normal male genital organ, normal 46 XY male chromosomes without any microdeletion. While his thermo-luminescence dosimeter indicated his cumulative radiation dose were only 17.81 mSv for 80 months, the radiation dose evaluated by biological assessments was shown to be near two Grey (Gy); The dicentric chromosome assay showed 0.882 Gy (0.597–1.183, 95% CI) and the 1, 2, 4 translocation assay indicated 1.913 Gy (1.358–2.591, 95% CI). Based on the biological assessment of radiation, he was approved for work-relatedness by compensation committee of the Korea Workers Compensation and Welfare Service. In this case report, we represent a case of azoospermia caused by occupational exposure of ionising radiation and suggest biological assessments as an alternative evaluating index for whose radiation exposure is uncertain.