Annals of Occupational and Environmental Medicine

Development of Physiologically Based Pharmacokinetic Model for Several Volatile Organic Compounds: Jae Yeon Jang, Kyung Jong Lee, Ho Keun Chung; Korean Journal of Occupational and Environmental Medicine 1997;9(2):357-377. Published online June 30, 1997; DOI: https://doi.org/10.35371/kjoem.1997.9.2.357

Abstract PDF: Recently physiologically based pharmacokinetic (PB-PK) model has important role in industrial and environmental health. One of problem in application of PB-PK models is that they have uncertainties that is due to different input parameters according to authors. In order to develope a PB-PK model that hag good validity, the effect of several input parameters on simulation results was studies. Chemicals studied were perchloroethylene, toluene and styrene. Simulation of alveolar concentration, blood concentration and urinary metabolites was performed for three solvents, respectively. Input parameters discusses were physiological parameters, metabolic parameters and partition coefficient of chemicals. By comparing simulation results according to several pairs of parameters with experimental data, input parameters that showed best fit were decided.

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Biomarkers of Susceptibility in Bladder Carcinogenesis: Sue Kyung Park, Hae Won Jung, Dae Hee Kang, Keun Young Yoo, Soo Hun Cho; Korean Journal of Occupational and Environmental Medicine 1997;9(2):341-356. Published online June 30, 1997; DOI: https://doi.org/10.35371/kjoem.1997.9.2.341

Abstract PDF: Owing to the development of molecular biological techniques to identify new biomarkers of bladder cancer, the information obtained from the studios in which newly developed biomarkers are applied potentially useful in screening of general population, diagnosis of patients, predicting biological behavior and prognosis, and exposure assessments. Despite of rapid development there are a few review about the biomarkers in bladder cancer from which grogs summary of results as well as their optimal function can be considered. This study was carried out in biomarkers of bladder cancer by reviewing the literature to assess the usefulness and stapes of researches for biomarkers of bladder cancer on high risk groups, general population and patients. The biomarkers of bladder cancer were classified by Weinstein's model of carcinogenesis, simple classification of exposure-discase in classical epidemiology, classification by conception of exposure-disease continuum on molecular epidemiology, and application of biomarkers. Two biomarkers, N-acetylation enzyme and Glutathion S-transferase, which had been studied extensively in molecular epidemiology were selected and reviewed. Although the generalization, prediction and diagnosis of bladder cancer based on a single biomarker give rise to trouble due to intravariation of bladder tumor and heterogeneity of biomarkers variation, searching for more specific tumor markers may accurately lead better prediction of prognosis and better estimation of treatment response. The usefulness of both N-acetylation enzyme and glutathion 5-transferase in high-risk groups who have exposes to carcinogen may be more valuable. However more informations are neede in order to apply these biomarkers in clinical practices in further studies.

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ALDH2 Genetic Polymorphism and Urinary Hippuric Acid Concentration in Toluene Exposed Workers: Oh Choon Kwon, Ree Joo, Jung Jeung Lee, Chang Yoon Kim, Jong Hak Chung, Seong Yong Kim; Korean Journal of Occupational and Environmental Medicine 1997;9(2):332-340. Published online June 30, 1997; DOI: https://doi.org/10.35371/kjoem.1997.9.2.332

Abstract PDF: In this study we evaluated the effects of the genetic polymorphism of aldehyde dehydrogenase2 (ALDH2) on toluene metabolism and determined biological exposure indices (BEIs) for toluene by the genotypes of ALDH2. The study subject were 77 men workers who are handling toluene in a video tape manufacturing factory and a textile company. Through the face-to-face interview, the information about smoking and drinking behavior wag obtained. For determination of ALDH2 poly morphism, 5 ml of venous blood sample was obtained from each subject after informed consent. DNA was extracted from the buffy coat and ALDH2 genotyping were performed using a polymerase chain reaction (PCR) method. The genotype of ALDH2 was classified into the homozygous genotype of normal ALDH2 (NN), and the heterozygous genotype of normal and inactive ALDH2 (ND), and homozygous genotype of an inactive ALDH2(DD). The concentration of hippuric acid (HA), the main metabolite of toluene, was determined in urine specimens collected at the end of shift, corrected with creatinine (HA/C), and compared with BEI for toluene, which is 2.5 g/g creatinine. The personal exposure level of toluene were monitored, using personal air sampler and analyzed by gas chromatography. The frequencies of the three genotypes in this study subjects were, NN : 45 (58.4%), ND : 26 (33.8%) and DD : 6 (7.8%), and frequencies of the genotypes in the middle or heavy toluene exposure workers were not significantly different from those in the mild toluene exposure workers. The frequencies of the DD type of ALDH2 was lower among alcohol drinkers than among non-drinkers. The urinary HA concentration of DD group was significantly lower than that of the NN or ND group, which suggests that the HA formation from toluene decreased in DD group. Regression lines were used to estimate the BEIs of the NN, ND, and DD groups. NN : y = 0.0085x + 0.23, r = 0.90 ND : y = 0.0074x + 0.21, r = 0.85 DD : y = 0.0041x + 0.82, r = 0.83 The three regression lines revealed that the estimated urinary HA concentration of NN, ND, and DD groups at 377 mg/m3 toluene(TLV-TWA) exposure were 3.43, 3.00, and 2.37 g/g creatinine, respectively. The HA concentration of the NN, and ND group were higher than that of the ACGIH BEI (2.5 g/g creatinine) ; however, the HA level of DD group was lower than the BEI. These results suggests that the ACGIH BEI is not adequate to estimate the toluene exposure of the NN, ND and DD groups at the same time. Based upon those results, a new BEI for ALDH2 deficient workers may be necessary.

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Effect of Cadmium on Cytokine Gene Expression in a Human Monocytic Cell Line, THP-1: Mi Jung Kang, Seon Hee Yang, In Sung Chung, Dong Hoon Shin, Kwan Kyu Park, Suk Kwon Suh; Korean Journal of Occupational and Environmental Medicine 1997;9(2):320-331. Published online June 30, 1997; DOI: https://doi.org/10.35371/kjoem.1997.9.2.320

Abstract PDF: Cadmium, a potent toxic metal, poses a serious environmental threat but the mechanism of its toxicity remains unclear. Also, cadmium is a known immunotoxic agent in animal studies and induces pathophysiological effects by modulating components of immune system. Cytokines are being increasingly recognized as essential mediators of normal and pathologic immune response. Cells of mononuclear phagocytic system are strategically located at portals of entry in humans and therefore may be particularly at risk for cadmium exposure through contaminated air, food, and drinking water. In the present study, we investigated the effect of cadmium cytotoxicity for the monocyte and expression of cytokine gene in the control and cadmium treated human monocytic cell lines using RT-PCR method. The results showed that cadmium inhibited cell proliferation at 0.1mM cadmium treated cells for 24 hours. The TNF-alpha mRNA was expressed in both control and cadmium treated cells but not IL-6 and IL-1 beta The mRNA levels of TNF-alpha were examined during 24 hours culture period, at different time points. The expression of TNF-alpha mRNA increased in both 0.01mM and 0.1mM cadmium treated cells, but did not show dose-response relationship. According to cadmium treated duration, expression of TNF-alpha mRNA was more decreases in 24 hours than 6 hours. The decreased levels of mRNA of TNF-alpha that cadmium suppresses iris production at the transcription level.

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The Stress Level According to the Working Status in the Migrant Workers: Myung Hee Lee, Chung Yill Park, Jung Wan Koo, Hyeon Woo Yim; Korean Journal of Occupational and Environmental Medicine 1997;9(2):309-319. Published online June 30, 1997; DOI: https://doi.org/10.35371/kjoem.1997.9.2.309

Abstract PDF

The number of foreign workers, which has increased since 1989, can be classified into industrial trainees and illegal migratory workers. As of January 1995, the official number of foreign workers reached 49,805 according to the Ministry of Labor. But the real number is estimated to be around 100,000 and industrial trainees are 22,583 among them. The stress induced by the culture shock, 3D (dirty, difficult and dangerous) working conditions, and illegal status of the foreign workers is greater than that of regular Korean workers. By using a psychological well-being index (PWI) measuring stress on 144 foreign workers, it was revealed that 68 people experienced "high risk stress", 76 "latent stress", and the average score was 62.8. The overall stress level was very high. Considering the distribution of high risk stress group and latent stress group by socio-demographic factors, the percentage of high risk stress group was higher among workers whose contract periods are less than 2 years than among workers whose contract periods are longer than 2 years. And the percentage of high risk stress group was higher when the number of workers at factory becoming larger, and also higher among workers who can not communicate well than among workers communicate well. After having a multiple stepwise regression analysis to find the socio-demographic factors which influence the PWI score, we found that the PWI score goes higher when the contract period is becoming shorter and the work hours is becoming longer, and these two factors are able to explain the score to the level 16.3%.

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Occupational Characteristics and Health Status of Vietnamese Male Migrant Workers in the Republic of Korea
Ohwi Kwon, Ji-Hun Song, Jeong-Ok Kong, Seong-Won Ma, Young Shin Lee, Joonho Ahn
Safety and Health at Work.2023; 14(3): 267. CrossRef

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Neuropsychiatric Symptoms of Workers Exposed to 2-Bromopropane: Kyeong Sook Choi, Byung Yeol Chun, Jung Sun Park, Yang Ho Kim, Young Hahn Moon; Korean Journal of Occupational and Environmental Medicine 1997;9(2):301-308. Published online June 30, 1997; DOI: https://doi.org/10.35371/kjoem.1997.9.2.301

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To investigate the impact of 2-bromopropane on neuropsychiatric symptoms, 33 exposed workers and 77 non-exposes workers in electronic company were recruited. Neuropsychiatric symptoms were assessed using self-administered questionnaire. Memory disturbance, concentration disturbance, sleep disturbance, understanding disturbance and acute irritation symptom were more frequent in workers exposed to 2-bromopropane. To investigate the association between 2-bromopropane exposure and neuropsychiatric symptoms, total symptom scores of exposed workers were compared with those of non-exposed workers. Mean value in the exposed workers was significantly higher than that of non-exposed comparisons. The mean value of total symptom score of smokers in exposed workers was significantly higher than that of smokers in non-exposed workers. In multivariate regression analysis, exposure status was significant predictor for total symptom score after controlling the effects of age, sex, education, smoking status and alcohol intake. Above findings suggest that 2-bromopropane was significantly associated with neuropsychiatric symptoms. Therefore, it is recommended that further research with objective assessments and long follow-up should be done to confirm the results of this study.

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Occupational Psychiatric Disorders in Korea
Kyeong-Sook Choi, Seong-Kyu Kang
Journal of Korean Medical Science.2010; 25(Suppl): S87. CrossRef

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Effects of the Chelating Agent on the Nephrotoxicity and Histopathological Change in Rat after Administration of Inorganic Mercury: Bong Suk Cha, Sang Baek Koh, Soon Won Hong; Korean Journal of Occupational and Environmental Medicine 1997;9(2):292-300. Published online June 30, 1997; DOI: https://doi.org/10.35371/kjoem.1997.9.2.292

Abstract PDF: This study was to determine the effects of Sodium-N-[4-methoxybenzyl]-D-glucamine-N-dithiocarbamate(MeOBGDTC) on the nephrotoxicity of mercury and histopathological change in rats pretreated with mercuric chloride 48h earlier. In a firsts experiment, 3 groups were given a single injection i.p. of 3.5 micromol/kg of HgCl2 mixed with 1microCi of 203Hg2+ in a final volume of 0.5ml of physiologic saline. Subsequently the rats also received the chelator, 1 mmol/kg of MeOBGDTC, at 1h in group 2 (HgCl2-MeOBGDTC 1h) and 12h in group 3 (HgCl2-MeOBGDTC 12h) after injection of mercuric chloride. The results showed that the injection of chelating agent at 1h after mercury injection significantly decreased mercury level in plasma. But not significant in renal cortex. In a second experiment, rats were divided into 4 groups, one group was control group, others were mercury injected group. MeOBGDTC was also administered to mercury-injected rats as described above. The changes in renal function were determined by measurement of proteinuria, plasma creatinine and urinary osmolality. The results showed that the injection of mercuric chloride increased the excretion of urinary protein and plasma creatinine, and decreased the urinary osmolarity. However, the injection of chelating agent at 1h after mercury injection significantly decreases the toxic effects of mercury. Finally, histopathological change at the light microscopic level was comparable effect of chelating agent on nephrotoxicity of mercury. Minimal morphological alterations were seen in kidney of rats of HgCl2-MeOBGDTC 1h. The HgCl2-MeOBGDTC 12h caused necrotic change of the proximal tubule at cortical-medullary junction. These changes were more common and more severe at the HgCl2 alone.

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A Case of Occupational Asthma Associated with Chromium: Hyun Sul Lim, Ji Yong Kim, Young Hyun Lee; Korean Journal of Occupational and Environmental Medicine 1997;9(2):283-291. Published online June 30, 1997; DOI: https://doi.org/10.35371/kjoem.1997.9.2.283

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Occupational asthma is an important occupation-related disease. We experienced a case of asthma induced by chromium. After discovery, chromium has been widely used in industry. Health effects of chromium and its compounds are contact dermatitis (allergic and irritant), mucosal irritation, basal septal perforation, asthma, and lung cancer. Their toxicity depends on valency, solubility, concentration, pH, exposure duration and route. The patient was a 47-year-old male and an ex-smoker. He complained of cough, sputum and dyspnea while working. Total eosinophil count was elevated but serum IgE value was normal. Bronchoprovocation test with 0.5 % (w/v) chromium solution revealed early and late asthmatic responses. Although his initial methacholine bronchial challenge test shoved a negative result, bronchial hyperresponsiveness developed after bronchoprovocation test with chromium solution. After discharge, he has complained of an intermittent dyspnea. It was suggested that chromium could induce occupational asthma in exposed workers. Further investigations are needed to clarify their pathogenetic mechanisms.

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Occupational Diseases in Korea
Seong-Kyu Kang, Eun A Kim
Journal of Korean Medical Science.2010; 25(Suppl): S4. CrossRef

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Study on the Cervicobrachial Syndrome Among Microwave-oven Assemblers (III) : A Review on Working Posture: Yang Ok Kim, Jong Park, So Yeon Ryu, Chul Gab Lee; Korean Journal of Occupational and Environmental Medicine 1997;9(2):275-282. Published online June 30, 1997; DOI: https://doi.org/10.35371/kjoem.1997.9.2.275

Abstract PDF: Working postures in 116 microwave-oven assemblers were measured and analysed using postural load scores of body parts in 137 workers complaining the cervicobrachial syndrome (CBS). The relationship between postural load scores of body parts and the grades of CBS was observed. Results were summarized as follows. 1. The height of work-table and work-seat, the thumb tip reach, the shoulder angle, the elbow angle and the forward bending angle of body trunk exceeded the recommended level and therefore they seemed to impose increased static postural loads on muscles of neck and shoulder as well as static and/or dynamic load on arm and hand muscles. 2. The postural load score of shoulder in grade II was significantly lower than that in grade III-2 and IV and those of elbow, neck+shoulder, elbow+wrist and upper extremity were significantly lower in grade II than in grade Iv. These results suggested that the awkward working postures were associated with the occurrence of CBS as well as the severity of CBS.

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Phototoxic Dermatitis by Coal Tar Containing Paint: Yun Chul Hong, Eun Hee Ha, Hye Sook Park; Korean Journal of Occupational and Environmental Medicine 1997;9(2):267-274. Published online June 30, 1997; DOI: https://doi.org/10.35371/kjoem.1997.9.2.267

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Many workers who used coal tar containing paints in shipyard industry have dermatitis, but the etiology is not known well. Our research is to fond out the etiology of the dermatitis and to provide proper management. Methods of this research are comprised of 3 steps. First, we diagnosed dermatitis by questionnaire and dermatologic examination and evaluated air level of coal tar pitch volatiles in workplace. Second, we confirmed coal tar phototoxicity by in vitro cell experiments. Third, we evaluated the effects of intervention. The results were as follows ; Questionnaire survey showed that the lesions of dermatitis were mainly on the sun exposed area and the symptoms were strongly associated with season, weather, and time. Air levels of coal tar pitch volatiles in workplace were higher than NIOSH standard (0.1 mg/m(3), cyclohexane solubles). Inhibitory effects of cellular proliferation by coal tar containing paints and UVA (365nm) exposure showed coal tar phototoxicity. Intervention was done by UV barrier cream(BPF 30) and 72.7% workers who applied UV barrier cream improved after 2 months later. Conclusively, the etiology of dermatitis of shipyard workers who used coal tar containing paint was coal tar phototoxicity, and this dermatitis would be protected by UV barrier cream.

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Overview of occupational cancer in painters in Korea
Jun-Pyo Myong, Younmo Cho, Min Choi, Hyoung-Ryoul Kim
Annals of Occupational and Environmental Medicine.2018;[Epub] CrossRef

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A Study of the Correlation Between the Activity of Erythrocyte Pyrimidine 5'-Nucleotidase and Urinary N-Acetyl-beta-D-Glucosaminidase in Lead Exposed Workers: Soung Hoon Chang, Cheon Hyun Hwang, Won Jin Lee, Soung Soo Lee, Byung Kook Lee, Hong Kyu Suh, Jae Wook Choi; Korean Journal of Occupational and Environmental Medicine 1997;9(2):258-266. Published online June 30, 1997; DOI: https://doi.org/10.35371/kjoem.1997.9.2.258

Abstract PDF: In this study, we measured the activity of the erythrocyte pyrimidine 5'-nucleotidase (P5N) and urinary N-acetyl-beta-D-glucosaminidase (NAG) from 154 workers exposed to lead and 43 workers not exposed. We analyzed the correlation of the P5N activity and NAG activity with other biological exposure indices of lead such as blood lead (PbB) and zinc protoporphyrin (ZPP). The measurement was performed by using high performance liquid chromatography (HPLC), spectrophotometer and atomic absorption spectrophotometer. The results are as follows: 1. The mean value of P5N activity for workers exposed to lead was 9.50+/-.13 micromol uridine/hr/g Hb and 11.60+/-.2 micromol uridine/hr/g Hb for workers not exported. The P5N activity showed a normal distribution, but the other indices of lead showed logarithmic normal distributions. 2. The P5N activity and ZPP were decreased as PbB wag increased. But the NAG activity had no correlation with changes of PbB. 3. The correlation coefficients of the P5N activity with other biological exposure indices of lead such as PbB, ZPP, NAG activity were -0.72, -0.55, and 0.05, respectively. We speculated that the P5N activity can be used as a reliable biological exposure index of lead but NAG activity can be used as a biological management index of lead.

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Effect of Noise Exposure and Psychosocial Factors on Blood Pressure in Manufacturing Workers: Bong Suk Cha, Sang Baek Koh, Sei Jin Chang, Jung Ku Park, Myung Guen Kang, Sang Yul Koh; Korean Journal of Occupational and Environmental Medicine 1997;9(2):244-257. Published online June 30, 1997; DOI: https://doi.org/10.35371/kjoem.1997.9.2.244

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This study was conducted to assess the effects of noise exposure and psychosocial factor on blood pressure in manufacturing workers. The study subjects are 414 workers (243 males, 171 females) employed at the noisy department. The mean age of low exposed group (<85dB) was 34.65+/-9.53 years, and that of high exposed group (> or =85dB) was 36.37+/-11.15 years. The difference in mean age wart not significant. The mean and distribution of working duration, smoking status, drinking status were not significantly different between two groups. The mean systolic blood pressure of the low exposed groups was 120.01+/-12.06 mmHg, and that of high exposed group wart 126.27+/-13.84 mmHg. The mean diastolic blood pressure of the low exposed and the high exposed group were 77.18+/-10.83 mmHg, and 83.46+/-11.22 mmHg respectively. These differences of blood pressure were statistically significant(p<0.05). The workers in noisy department have significantly less work environmental satisfaction, higher job demand, and higher social support. The mean values of psychosocial distress were higher in the workers of the noisy department, but the difference was not statistically significant. This study was to speculate whether the work environmental satisfaction and social supports modify the association between the noise exposure level and the blood pressure. The results showed that work environmental satisfaction could not modify the association between the blood pressure and the noise exposure. Social support at work did not modify the association. Furthermore, we evaluated the high job strain from a combination of high job demand and low job control at work. Compared to the low strain group, the olds ratio of the high job strain group for hypertension in diastolic blood pressure were statistically significant, but not in systolic blood pressure. Hierarchical multiple regression analysis was used to determine whether the independent variables contributed to explaining the blood pressure. After controlling for possible confounders, we found that the noise exposure level was a correlate of the diastolic blood pressure. But no association between the noise exposure level and the systolic blood pressure. No significant result was found for psychosocial factor.

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Relationship Between the Psychosocial Factors and Job Stress Among Clerical Public Officers
Ho-Jin Park, Sung-Kyeong Park, Young-Chae Cho
Journal of the Korea Academia-Industrial cooperation Society.2014; 15(9): 5610. CrossRef
Relationships Between Job Stress and Psychosocial Stress Among Nurses in a University Hospital
Sung-Kyeong Park, Jong-Oh Kim, Young-Chae Cho
Journal of the Korea Academia-Industrial cooperation Society.2011; 12(9): 3887. CrossRef

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Biological Indices for Early Detection of Cadmium Poisoning: Significance of Urinary Metallothionein: Jung Duck Park, Yeon Pyo Hong, Im Won Chang; Korean Journal of Occupational and Environmental Medicine 1997;9(2):230-243. Published online June 30, 1997; DOI: https://doi.org/10.35371/kjoem.1997.9.2.230

Abstract PDF: Metallothionein(MT) is a low molecular weight protein that is induced as a defence mechanism for cadmium (Cd) toxicity. In present study, urinary MT was determined using a competitive ELISA in Cd-exposed rats. In addition, measures the urinary, blood and renal Cd concentration and the urinary excretion of total protein, beta 2-microglobulin (MG) and N-acetyl-beta-D-glucosaminidase(NAG) at 1, 3, 7, 14, 28 days after Cd injection in Cd-exposed rats with dosers of 0.8 and 1.6 mg Cd/kg body weight respectively. The urinary, blood and renal Cd were specific for Cd-exposure, that increased in proportional to dose of Cd. The urinary and blood Cd tended to slightly decrease, while renal Cd tended to increase by lapse of time after Cd exposure. this finding indicates that renal Cd is more specific than urinary and blood Cd for Cd exposure. The urinary excretion of MT showed a statistically significant increase in Cd exposed rats(0.8 and 1.6 no Cd/kg body weight). The increase of urinary excretion of MT was more evident at 7, 14, 28 lays after Cd exposure than the changes of urinary excretion of total protein, beta-MG and NAG. The Pearson's correlation coefficients between urinary Cd and urinary MT, beta-MG, NAG and total protein were 0.4344, 0.3727, 0.3307 and 0.2099, respectively. These findings indicate that the urinary MT is more sensitive and specific than total protein, beta-MG and NAG for Cd exposure. The present results suggest that the urinary MT, using a simple and rapid competitive ELISA, is a valuable index as screening test in epidemiologic study for Cd exposed group.

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The Metabolism and Liver Toxicity of N, N-dimethylformamide in the Isolated Perfused Liver: Sang Baek Koh, Bong Suk Cha, Myung Guen Kang, Sang Yeol Koh, Jung Woo Lee, Sang Ok Kwon; Korean Journal of Occupational and Environmental Medicine 1997;9(2):217-229. Published online June 30, 1997; DOI: https://doi.org/10.35371/kjoem.1997.9.2.217

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N, N-dimethylformamide (DMF) is a solvent which is widely used in the industrial workplace. It causes the liver damages to the chronically exposed workers and is also well known as the harzadous material to generate occupational malignancies. DMF is mainly metabolized into N-hydroxymethyl-N-methylformamide (HMMF) by the microsomal cytochrome p-450. HMMF breaks down to NMF. However, the detailed mechanism of its toxicity are unknown. In this experiment, the metabolism and the toxicity of DMF was investigated using an isolated perfumed liver model. DMF (0, 10, 25mM) were added into recirculating perfusate of the isolated perfused rat liver. Samples were collected at 0, 30, 45, 60, 75, 90 minutes from inferior vena cava. The gas-chromatography was used to analyze the metabolite of DMF, The changes in the oxygen consumption rate by DMF were monitored during perfusion. The enzyme activity (AST, ALT, LDH) in the perfusate were treasured to find out whether DMF causers hepatotoxicity. As perfusion continued, DMF concentration in the perfusate decreased, and NMF 1.16mM was detected. The oxygen consumption rate increased both at 10mM and 25mM DMF concentration. However, when SKF 525A, a known inhibitor of cytochrome p-450, had been pretreated (300uM before DMF addition, the oxygen consumption rate was significantly inhibited, indicating that cytochrome p-450 system is responsible for the conversion to NMF. With DMF addition, the activity of AST, ALT, and LDH significantly increased time dependently and dose dependently. However, the pretreatment of perfused liver with SKF 525A shoved that the release of AST, ALT and LDH was inhibited. In summary, it is found that DMF is metabolized to NMF in liver, and that cytochrome p-450 mono-oxygenase is suggested to play a role in the biotransformation of NMF. The time course of BMF toxicity in relation to NMF formation is compatible with hypothesis that the hepatotoxicity of DMF is mediated via NMF. Further study combined with in vivo experiment through the toxicological approaches is expected.

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Clinical Outcomes of Occupational Exposure to N,N-Dimethylformamide: Perspectives from Experimental Toxicology
Tae Hyun Kim, Sang Geon Kim
Safety and Health at Work.2011; 2(2): 97. CrossRef

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Neurobehavioral Effects of Low Level Lead-exposed Workers at CRT(Cathode Ray Tube) Manufacturing Factory: Jong Young Lee, Chae Yong Lee, Ji Suk Kim, Sang Jae Lee, Wan Seoup Park, Kuck Hyeun Woo; Korean Journal of Occupational and Environmental Medicine 1997;9(2):208-216. Published online June 30, 1997; DOI: https://doi.org/10.35371/kjoem.1997.9.2.208

Abstract PDF: To assess neurobehavioral effects of 48 low level lead-exposed workers in CRT manufacturing factory, simple and choice reaction time test with NTOS (Neurobehavioral Tests for Occupational Screening), digit symbol and digit span with K-WAIS (Korean Wechsler Adult Intelligence Scale), and SCL-90-R (Symptom Check List 90 revised) was examined. These screening test battery reflect 3 psychological domain; psychomotor, short term memory, and symptom. Average blood lead level was 17.7 microgram/dl and mean exposure duration was 5.6 years. Nobody exceeded blood lead level over 40 microgram/dl, the guideline. We divided workers to two group, shorts-term exposed group(< or = 5 years) and long-term exposed groups 5 years) for analysis. ANCOVA model of simple reaction time, hostility, phobic anxiety, somatization were statistically significant and coefficient of independent variable of exposure duration was also significant. MANCOVA model of SCL-90-R was significant, too. The results of this study were consistent with previous study; symptoms were early neurobehavioral effects of low level lead exposure. And this study showed that current blood lead level as independent variable was able to mask the early neurobehavioral effects.

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Significance of Time-dependent Exposure Variable in Occupational Disease Study: Jai Dong Moon; Korean Journal of Occupational and Environmental Medicine 1997;9(2):201-207. Published online June 30, 1997; DOI: https://doi.org/10.35371/kjoem.1997.9.2.201

Abstract PDF: Although the final cumulative exposure has been used as a exposure variable on the cohort study for the relation between exposure and disease, the bias from the use of fixed exposure can be developed because the exposure amount changes across the time. We developed the program to handle the Cox model with irregularly changing time-dependent exposure variable and covariates, and the validity about the application of time-dependent exposure variable and lagged interval was practically evaluated by analyzing the data collected for typical retrospective cohort study with that program. The results were as follows : The exposure-response relations between the deaths from lung cancer and exposures (fixed or time-dependent) were not clear when 0 year lagged interval was applied. When 15 years lagged interval was applied, the exposure-response relations between the deaths from lung cancer and the time-dependent exposures to crystalline silica were observed and relative risky increased like 1.00, 1.17, 1.30 and 2.45 across the exposure levels. The relative risk estimates for lung cancer with time-dependent exposure variable were higher than those with fixed exposure variable without regard to the application of lagged interval. The exposure-response relations between the deaths from non-malignant respiratory disease (NMRD) and exposures (fixed or time-dependent) were observed across exposure levels when 0 year lagged interval was applied. When 15 years lagged interval wag applied, the exposure-response relations between the deaths from NMRD and the time-dependent exposures to crystalline silica were observed, but were not with fixed exposure variable. The relative risk estimates for NMRD mortality with time-dependent exposure variable were higher than those with fixed exposure variable, and the application of lagged interval on the evaluation of NMRD mortality was meaningless. The results suggests that the application of time-dependent exposure variable on the study of exposure-effect relation should be considered and the application of lagged interval should be decided according to the time needed from disease detection to death.

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