Synergistic effect of hepatitis virus infection and occupational exposures to vinyl chloride monomer and ethylene dichloride on serum aminotransferase activity

Aims: To study the synergistic effect of occupational chemical exposure and hepatitis virus infection on serum aminotransferase activity. Methods: A total of 568 male workers who were employed in five polyvinyl chloride (PVC) or four vinyl chloride monomer (VCM) manufacturing factories were studied. Information relating to current job title, alcohol consumption, and cigarette smoking was obtained. Exposure level of chemical mixtures was classified by hygienic effect (a summation of personal time weighted average/reference permissible exposure level of each chemical) into high, moderate, and low exposure groups. Serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT), hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg), and anti-hepatitis C antibody were assayed. Results: Hepatitis virus infection and increased body mass index were associated with abnormal serum aminotransferase activity. In workers with hepatitis virus infection, those with high exposure had a higher prevalence of abnormal AST and ALT compared to low exposure; among those without hepatitis virus infection, the differences of prevalence of abnormal AST and ALT were not significant between different chemical exposure groups. There was a significant trend of increasing risks of increased AST and ALT in moderate and high exposure groups with hepatitis virus infection. Such a synergistic effect was more prominent among HBeAg-positive workers. Conclusions: Mixed exposures to 1,2-ethylene dichloride and VCM have a positive synergistic effect with hepatitis virus infection on liver damage. Assessment of fitness for work should be considered in workers with hepatitis B and C infection, when they have potential exposure to hepatotoxins in the workplace.     

二甲基甲酰胺对接触工人肝功能的影响

目的探讨二甲基甲酰胺(DMF)接触浓度、饮酒量及其他因素对DMF接触工人肝功能的影响。方法根据工厂前2年车间空气的监测数据,将DMF分为对照组、低接触组及高接触组。采用问卷调查了解各组研究对象的基本情况及饮酒习惯,采集血样测定肝功能。结果低接触组和高接触组血清丙氨酸转氨酶(ALT)及γ-谷氨酰转肽酶(γ-GT)水平明显高于对照组,高接触组血清天冬氨酸转氨酶(AST)水平高于低接触组;高接触组肝脏指数(Liver index)明显高于对照组和低接触组。多元线性回归分析表明ALT、γ-GT、肝脏指数与接触DMF及体重指数(BMI)相关,ALT还与甘油三酯(TRIG)相关,AST只与工人的饮酒量相关。在肝功能异常者中,有86.7%的AST/ALT比值<1。结论DMF能影响接触工人肝功能,肥胖及饮酒量有一定的协同作用。肝脏指数和AST/ALT比值可作为肝损伤评价和筛选指标。     

Abnormal liver function associated with occupational exposure to dimethylformamide and hepatitis B virus

N,N-Dimethylformamide (DMF) has excellent solvent properties and is used intensively in the production of synthetic leather and resins. It has caused hepatoxicity in human and animal studies. Hepatitis B virus (HBV) and hepatitis C virus infections are reported to be the major causes of chronic liver diseases (including liver cirrhosis and liver cancer) in Taiwan. This study examined the dose-response relationship of the observed abnormal liver function among the DMF-exposed workers and the interactions among DMF, other chemical exposures, HBV infection, and potential confounders on liver abnormalities. The average DMF exposure concentration was 11.6 ppm (median, 5.9 ppm; range, 0.1 to 86.6 ppm); 65 of 176 workers (36.9%) had high (> 10 ppm) DMF exposure, 37 (21%) had middle (> 5 ppm, < or = 10 ppm) exposure, and 74 (42%) had low (< or = 5 ppm) exposure. There were 24 of 65 abnormal liver function test results (LFTs) (36.9%) (elevations of either glutamate oxaloacetate transaminase, glutamate pyruvate transaminase, or gamma-glutamyl transpeptidase) among the workers with high DMF exposure, 10 of 37 abnormal LFTs (27%) among workers with middle DMF exposure, and 11 of 74 abnormal LFTs (22%) among workers with low DMF exposure. Compared with the workers having low DMF exposure, the HBV, drinking, body mass index (BMI), sex, duration of employment, epichlorohydrin, and toluene exposure adjusted odds ratios (ORs) (and 95% confidence intervals [CIs]) for abnormal LFTs were 1.62 (0.61, 4.28) for workers with middle DMF exposure and 2.93 (1.27, 6.8) for those with high DMF exposure, and there was a significant dose response between DMF exposure and the prevalence of abnormal LFTs (P = 0.006). There were significant associations between abnormal LFTs and HBV carriers (adjusted OR: 3.11; 95% CI: 1.29, 7.5; P = 0.01) and between abnormal LFTs and increased BMI (adjusted OR: 2.2; 95% CI: 1.02, 4.72; P = 0.041). Ultrasonography showed significant associations between chronic liver diseases and HBV carrier status, increased BMI, and high cumulative (> 100 ppm-years) DMF exposure (respectively, adjusted OR: 9.58, 95% CI: 1.79, 51.4, P = 0.007; adjusted OR: 13.2, 95% CI: 1.32, 132, P = 0.025; and adjusted OR: 6.2, 95% CI: 1.14, 34.1, P = 0.032). Drinking and BMI were significantly associated with fatty liver (respectively, adjusted OR: 4.9, 95% CI: 1.39, 17.3, P = 0.012; and adjusted OR: 7.93, 95% CI: 1.6, 39.3, P = 0.01). In conclusion, this study demonstrated that (1) a significant dose-response relationship existed between liver function abnormalities and DMF exposure among workers in Taiwan, (2) HBV carrier status or increased BMI had synergistic effects with DMF in causing liver abnormalities (abnormal LFTs and clinical chronic liver diseases).     

某焦化厂职业接触多环芳烃焦炉工肝脏某些酶活性的变化

目的探讨多环芳烃(PAHs)对炼焦作业工人某些肝血清酶活性改变的可能影响。方法对乙肝表面抗原(HBsAg)阴性的炼焦作业工人和非PAHs职业接触工人进行总PAHs累积接触指数(CEL-PAHs)评估,尿中1-羟基芘(1-OHP)浓度等级划分,和血清中丙氨酸转移酶(ALT)、天门冬氨酸转移酶(AST)、γ-谷氨酰转移梅(GGT)、碱性磷酸酶(ALP)的检测。结果焦炉工职业性PAHs暴露水平明显高于对照组(P<0·05)。与对照组相比,血清ALT的明显升高可见于CEL-PAHs<50μg/(m3·a)组和尿中1-OHP浓度<2·3μmol/mol肌酐CEL-PAHs≥200μg/m3组,血清AST的明显升高可见于CEL-PAHs<50μg/(m3·a)组;当CEL-PAHs(200μg/(m3·a)或尿中1-OHP浓度≥10·0μmol/mol肌酐时,可发现四种肝生化指标实测值的明显升高(P<0·05),以及ALT、AST和GGT异常率的明显升高(P<0·05),以血清GGT水平的升高(10倍CEL-PAHs的上升导致1·24倍血清GGT水平的升高,10倍尿中1-OHP浓度的上升导致1·19倍的升高)和异常率的上升(logistic回归,调整OR值为6·2~7·2,P<0·05)最为明显。结论PAHs职业暴露可导致炼焦作业工人肝脏某些血清酶活性的升高。     

ZnCl2对二甲基甲酰胺所致小鼠急性肝毒性的保护作用研究

目的 研究ZnCl2对二甲基甲酰胺(N,N-dimethylformamide,DMF)致小鼠急性肝损伤的保护作用,为保护DMF接触人群提供指导.方法 将80只动物随机分为8组:正常对照组、DMF组、ZnCl2-10 DMF组、ZnCl2-20 DMF组、ZnCl2-40 DMF组、ZnCl2-10组、ZnCl2-20组和ZnCl2-40组.所有ZnCl2给药组每天皮下注射一定剂量的ZnCl2溶液.ZnCl2-10、ZnCl2-20和ZnCl2-40组在DMF染毒之前,其余组在DMF染毒后48 h处死小鼠,测定其血清丙氨酸氨基转移酶(ALT)、天门冬氨酸氨基转移酶(AST)和乳酸脱氢酶(LDH)的活力;制备肝匀浆,测定ZnCl2-10、ZnCl2-20和ZnCl2-40组小鼠肝金属硫蛋白(MT)含量;留取肝脏组织,常规石蜡包埋切片,HE染色,光镜观察肝脏组织病理变化.结果 与正常组比较,DMF组小鼠血清中ALT、AST和LDH活力明显升高,肝脏组织出现明显的肝细胞变性坏死;ZnCl2 DMF组的小鼠血清中ALT、AST和LDH活力与DMF组相比明显降低,肝脏组织病理损伤明显减轻.单独给予ZnCl2组小鼠MT含量升高.结论 ZnCl2对DMF引起的小鼠急性肝损伤具有明显的保护作用.     

HBsAg carriers among healthy Nepalese men: a serological survey

The prevalence of hepatitis B surface antigen (HBsAg) was studied among 2,585 healthy Nepalese men, aged 16-50 years, who required medical check-ups for employment abroad. Serum samples, collected during July-September 1999, were tested for HBsAg using a third-generation ELISA kit. Of the 2,585 men, 24 (0.93%) were positive for HBsAg, indicating that hepatitis B infection in the target group was below the intermediate endemicity. The prevalence of HBsAg was minimum (0.36%) in the central development region, followed by western, eastern and mid-western development regions (0.82%,1.16%, and 2.08% respectively, chi2 = 4.76, p < 0.2). The positivity of HBsAg was slightly higher in the hilly region (1.11%) than in the terai (0.84%) and mountainous regions (0%), which was not significant (chi2 = 2.1, p < 0.5). The prevalence was highest in the 46-50-year age group. Alanine aminotransferase was tested in all 24 positive and 150 negative subjects to indicate the stage of infection. Seven (29.16%) of the 24 positive cases had elevated alanine aminotransferase, indicating associated liver damage (chi2 = 4.16, p < 0.05) and it was significantly associated with positivity of HBsAg (chi2 = 32.6, p < 0.001). All 9 positive subjects from the terai region had normal alanine aminotransferase, whereas 7 of the 15 subjects from the hilly region had it elevated (chi2 = 1.76, p < 0.001). Seven (29%) of the positive subjects were chronic carriers with its sequel in the liver, and the remaining 17 subjects (70.84%) may be in the incubation period or convalescent stage or may be chronic carriers. The results suggest that the population should be educated about the sequel of the infection.     

Interaction of vinyl chloride monomer exposure and hepatitis B viral infection on liver cancer.

Vinyl-chloride monomer (VCM), a human carcinogen, has caused angiosarcoma of the liver. Recent studies have shown that VCM exposure is associated with hepatocellular cancer. In Taiwanese studies, the majority of VCM-exposed workers with liver cancer had history of hepatitis B virus (HBV) infection. To determine the role of HBV on the development of liver cancer in the VCM-exposed workers, we conducted a case-control study from a previously established polyvinyl chloride (PVC) cohort consisting of 4096 male workers from six PVC polymerization plants. A total of 18 patients with liver cancer, and 68 control subjects matched for age and specific plant of employment were selected. Detailed history of the participants that included alcohol consumption status, cigarette use, occupation, and family history of chronic liver disease were obtained using an interviewer-administered questionnaire. When the HBV surface antigen (HBsAg)-negative subjects without history of tank-cleaning were used as the reference, the HBsAg-negative subjects with history of tank-cleaning demonstrated a 4.0-fold greater risk of liver cancer (95% confidence interval: 95% CI = 0.2-69.1). The HBsAg carriers without history of tank-cleaning revealed a 25.7-fold greater risk of liver cancer (95% CI = 2.9-229.4). Whereas the HBsAg carriers with history of tank-cleaning revealed the greatest risk (matched odds ratio (ORm) 396.0, 95% CI = 22.6 -infinity) of developing liver cancer among subjects with different VCM-exposure status and HBsAg status categories. Further analysis showed the interaction term was significant (P < .01). Therefore, our results suggest an interaction between occupational VCM exposure and HBV infection for the development of liver cancer.     

Increased risk for hepatitis B-related liver cirrhosis in relatives of patients with hepatocellular carcinoma in northern Taiwan

BACKGROUND: There is a tendency for familial aggregation of hepatocellular carcinoma (HCC). The aims of this study were to assess the degree to which familial aggregation of hepatitis B surface antigen (HBsAg) carriers accounts for familiality of HCC in families of hepatitis B-related HCC patients, and whether HCC shares a familial predisposition with liver cirrhosis among HBsAg carriers. METHODS: A total of 671 first-degree relatives of HBsAg-positive HCC cases were recruited using abdominal ultrasonography and tests for HBsAg and serum aminotransferases. They were from 165 simplex families defined as having only one HCC case and 72 multiplex families with more than one case. In analyses of family history of HCC and cirrhosis, the data set consisted of 4,471 unrelated asymptomatic HBsAg carriers recruited in a prospective study. RESULTS: There was no significant difference in the HBsAg-positive rate among relatives between multiplex (55.7%) and simplex (48.1%) families. Sonographic evidence of liver cirrhosis was present in 14.4% of HBsAg-positive relatives from multiplex families but in only 7.8% of HBsAg-positive relatives from simplex families (multiplex versus simplex families: adjusted odds ratio [OR] = 2.29; 95% CI: 1.10-4.77). Among unrelated asymptomatic HBsAg carriers, the adjusted OR of liver cirrhosis associated with a first-degree family history of HCC was 2.80 (95% CI: 1.68-4.66). This association was stronger in HBsAg carriers <50 years. No association was seen between family history of HCC and hepatitis activity based on elevated levels of aminotransferases. CONCLUSIONS: Familial aggregation of HCC in HBsAg carriers is associated with familial clustering of liver cirrhosis.     

二甲基甲酰胺对作业工人健康影响的调查研究

目的探讨二甲基甲酰胺(DMF)职业接触对工人肝脏、心脏的影响。方法根据职业接触DMF状况和作业场所空气监测数据,将某合成革企业573名男性职工分为3组,分别为对照组、低浓度接触组和高浓度接触组,进行问卷调查和肝功能常规检查;同时,从接触组抽取63人进行心肌酶谱检测,对结果进行分析。结果高浓度接触组丙氨酸氨基转移酶(ALT)、总胆红素水平及心电图异常率明显高于低浓度组和对照组,差异有统计学意义(P<0.05)。心电图异常组肌酸激酶同工酶(CK-MB)水平明显增高,差异有统计学意义(P<0.05)。结论长期暴露于DMF不仅可对工人肝脏造成损伤,而且会导致心肌损伤。     

Abnormal liver function in workers exposed to low levels of ethylene dichloride and vinyl chloride monomer

We investigated whether exposure to ethylene dichloride (EDC) and vinyl chloride monomer (VCM) resulted in increased risk of liver damage. Epidemiological information, including occupational, medical, smoking, and drinking history, was obtained by interview from 251 male workers. Serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), and gamma-glutamyltransferase (GGT) were used as indicators of liver damage. Exposure to moderate or low levels of ECD and VCM resulted in a higher risk of developing abnormal ALT levels than did exposure to lower levels of the chemicals. Results were similar for AST. GGT was not associated with EDC or VCM exposure. Combined exposure to EDC and VCM showed a dose-response relationship in association with abnormal ALT levels. We concluded that relatively low concentrations of VCM and EDC cause liver damage.     

656例乙肝病毒检测与肝损伤的相关性分析

目的:探讨乙型肝炎患者病毒标志物的水平与肝损伤的相关关系。方法:丙氨酸氨基转移酶(ALT)、天门冬氨酸氨基转移酶(AST)用连续监测法,白蛋白(ALB)用溴甲酚绿法,总胆红素(T-BIL)用矾酸氧化法,C反应蛋白(CRP)用免疫散射比浊法,乙肝五项(HBsAg、HBsAb、HBeAg、HBeAb、HBcAb)用时间分辨荧光免疫分析法,乙肝病毒DNA(HBV-DNA)用实时荧光定量PCR法。结果:不区分炎症活动期乙肝病毒标志物与肝损伤之间无明显的相关关系(均P>0.05);炎症活动期乙肝病毒标志物水平与肝损伤有一定的相关关系(P<0.05)。结论:乙肝炎症活动期定量检测乙肝病毒标志物和HBV-DNA水平,对评价乙肝患者肝细胞损伤程度有一定的意义。     

隆安县HBsAg携带者乙型肝炎病毒DNA、ALT调查

[目的]了解广西壮族自治区隆安县HBsAg携带者血清乙型肝炎病毒（HBV）DNA、丙氨酸氨基转移酶（ALT）情况。[方法]对广西隆安县30～55岁HBsAg携带者组成的研究队列采空腹静脉血,利用套式聚合酶链激反应（nPCR）检测血清HBV DNA,利用赖氏法测血清ALT,根据HBV DNA检测结果将研究对象分为两组,HBVDNA（＋）组和HBVDNA（-）组。比较人群ALT异常率。[结果]HBsAg携带者HBV DNA阳性率为53．34％（1008／1855）,ALT异常率为17．41％（323／1855）,男性HBVDNA阳性率（56．69％,589／1039）、ALT异常率（22．14％,230／1039）均高于女性（51．35％、419／816,11．40％、93／816）（均P〈O．05）,HBVDNA（＋）组ALT异常率（23．21％）高于HBVDNA（-）组（10．51％）（Pd0．01）;40～岁年龄组ALT异常率（19．18％）最高,各年龄组ALT异常率的差异无统计学（P〉0．05）。[结论]该地区HBsAg携带者高HBV复制率、肝功能受损是肝癌高发的危险因素之一。     

Hepatitis B and C infection: Is it a problem in Polish healthcare workers?

Objectives

Hepatitis B (HBV) and C viruses (HCV) are among the most frequent blood borne pathogens. According to WHO, 5% of healthcare workers (in central Europe), are exposed to at least one sharps injury contaminated with HBV per year, 1,7% — contaminated with HCV.

Aims

The aims of the study were to determine prevalence of HCV and HBV infections, vaccination efficacy against hepatitis B and usefulness of alanine aminotransferase (ALT) testing in prophylactic examinations in healthcare workers (HCWs).

Material and Methods

In a group of 520 healthcare workers, a survey, laboratory and serologic tests such as ALT, HBsAg, anti-HBs, anti-HBcT and anti-HCV were carried out.

Results

The study revealed a low rate of workers with presence of HBsAg and anti-HCV (1,2% and 0,8% respectively). Anti-HBcT was found in 99 subjects (19%) without a significant association with experiencing an occupational percutaneous injury. Being vaccinated against HBV was declared by 90% of the subjects. There was no relationship between ALT level rise and positive HBsAg, anti-HCV and anti-HBcT tests.

Conclusion

A seroprevalence of HBV and HCV markers in HCWs found in the study is low and similar to the one found in general population. Current or past hepatitis B infections were independent of needle stick injuries. Vaccination against HBV coverage, although found to be high, should improve to 100%. Occupational prophylactic medical examinations found performing ALT test (obligatory in Poland for HCWs) not helpful. It seems that determination of anti-HBcT and anti-HCV status would be essential in pre-employment medical examinations.     

Causal relationship between a case of severe hepatic dysfunction and low exposure concentrations of N,N-dimethylformamide in the synthetics industry

A 19-year-old man suffered hepatic dysfunction after 5 months of exposure to N,N-dimethylformamide (DMF) at his job in the synthetic resins industry. Laboratory data revealed elevated levels of AST (578 IU/l), ALT (1193 IU/l), and gamma-GTP (107 IU/l), no viral infection with HAV, HBV, or HCV, and no history or evidence of hepatic injury, although he did have a slight abdominal abnormality and swelling which was detected by palpation. His urinary N-methylformamide level, as a biological exposure index of DMF, was 42.8 mg/l, indicating 10-30 ppm of DMF exposure. After 2 months he was reinstated in two workplaces, the former where he worked in the morning and the other in the afternoon where environmental DMF concentrations were less than those in the former workplace. On the 18th day after his reinstatement, his liver function became exasperated again. After the second period of medication and one month of rest from work, he had fully recovered and was reinstated, but to a workshop without DMF exposure.     

人造革厂工人二甲基甲酰胺经皮接触评估研究

目的 对人造革厂工人经皮肤接触二甲基甲酰胺(DMF)的水平进行评估。方法 采用洗手法和擦拭法对某人造革厂湿法配料、湿法涂台和三版印刷工人进行皮肤接触水平监测,同时对工人的吸入水平及尿中甲基甲酰胺(NMF)水平进行检测。结果 所有洗手液和擦拭液样品中均检测出DMF(洗手液：0.35～15.34 mg;擦拭液：29.58～110.45μg)。在洗手试验组中,洗手液中DMF总量与作业人员班末尿中NMF含量、累积接触水平与班末尿中NMF含量呈对数相关性;擦拭试验组中则各指标间无相关性。结论 洗手法是一种较好的研究DMF作业人员皮肤接触水平的方法,具有容易在现场实施以及结合生物监测结果等优点。     

Liver function assessment in workers exposed to vinyl chloride

Objective: To investigate liver function in vinyl chloride workers and assess its relation with current/past occupational exposure to vinyl chloride monomer (VCM). Methods: A medical examination including the execution of liver function tests (LFTs) and liver ultrasonography was executed in a group of 757 workers with a long-standing service in the production of VCM/polyvinylchloride (PVC). Cumulative and maximum VCM exposures were calculated. History of viral hepatitis and alcohol intake were carefully investigated. Regression analysis explored the association between abnormal LFTs and a group of possible determinants (VCM cumulative and maximum exposure, BMI, age, history of viral hepatitis, alcohol and triglyceride levels). Also, synergistic effect between VCM and a history of hepatitis was analysed, as well as the possible association between VCM exposure and aspartate aminotransferase/alanine amino transferase (AST/ALT) ratio >1. Distribution of abnormal LFTs was also assessed in relation to the results provided by liver ultrasonography. Results: The most frequently abnormal serum parameters were, in decreasing order: total cholesterol (27.3%), triglycerides (12.2%), total bilirubin (9.1%), gamma glutamil transpeptidase (GGT; 9.0%) and ALT (8.2%). The AST/ALT ratio >1 was present in 28.1% of workers. Abnormal LFTs were not found to be associated with current or past VCM exposure. High ALT resulted positively associated with BMI, AST with alcohol intake, GGT with alcohol intake and triglycerides. No synergistic effect on LFTs of exposure to VCM and a history of hepatitis was observed. The AST/ALT ratio >1 was not found to be associated with VCM exposure. The prevalence of abnormal LFTs was higher in case of liver steatosis (ALT) or periportal fibrosis (GGT), but not in case of pure hepatomegaly, as documented by ultrasonography. Conclusions: Liver function assessment only including LFTs is not able to detect VCM-induced liver damage, but reveals alterations due to non-occupational factors, such as dietary and/or metabolic disfunctions. The LFTs are however of importance to detect conditions that could recommend avoidance of exposure to VCM and are useful for medical counselling and health promotion purposes.     

Exposure to solvents in a synthetic leather manufacturing plant

The objective of this study was to evaluate the exposure of synthetic leather workers to dimethylformamide (DMF), epichlorohydrin (ECH) and toluene, in a manufacturing plant. The correlation between biological and environmental monitoring for DMF was also investigated. Environmental monitoring of the three solvents included personal and area sampling based on time of day (morning and afternoon). Urine samples were taken at the end of the shift and urinary N-methylformamide (NMF) was then used to biologically monitor DMF levels. Results for solvent concentrations based on air sampling were considerably higher in area than in personal sampling. Of 41 area samples, 15 (36.6%) and five (12.2%) exceeded permissible exposure levels for DMF and ECH, respectively, compared with 22 (28.6%) and three (3.9%) based on 77 personal samples. Overall, urinary NMF concentrations were lower than the Biological Exposure Index (BEI) suggested by the American Conference of Governmental Industrial Hygienists (ACGIH). A significant correlation (r=0.32; P < 0.05) was found between environmental and biological monitoring. Even though urinary NMF concentration was within permissible levels for Taiwan, the authors recommend that immediate measures be taken to decrease DMF and ECH concentrations in synthetic leather manufacturing plants. Received: 14 June 1999 / Accepted: 20 November 1999     

Liver changes in workers at an oil refinery and in a reference population in the state of Bahia, Brazil]

OBJECTIVE: To determine the prevalence of liver changes in workers at an oil refinery located in the state of Bahia, Brazil, as compared to a reference population with no occupational exposure to chemical products, and to describe the factors associated with the observed differences in prevalence. METHODS: We studied workers at the refinery and at the company's central management office located in the city of Salvador, which is the state capital. Blood samples of 692 refinery workers and 377 workers from the reference population were analyzed. Cases were defined as individuals presenting high serum levels of both gammaglutamyltransferase (GGT) and alanine aminotransferase (ALT) (GGT > 50 U/L for males and > 32 U/L for females; ALT > 50 U/L). Data were collected on age, sex, weight, height, years working for the company, use of alcohol, smoking habits, physical exercise, occupational exposure to chemical products, use of personal safety equipment, and medical history of hepatitis, jaundice, and obesity. RESULTS: The prevalence of liver changes among refinery workers was 15.3% (95% CI: 12.5 to 18.1), vs. 3.8% (95% CI: 1,8 to 5,8) in the reference population. According to multiple logistic regression analysis, the prevalence of liver changes among refinery workers was 3.56 times greater (95% CI: 1,99 to 6,38) than in the reference population, regardless of the presence of other relevant co-variables, such as obesity, exercise, smoking, and alcohol consumption. CONCLUSIONS: These results suggest that occupational exposure may play a major role in the development of liver changes among workers at the oil refinery where the study was carried out.     

The prevalence of TT virus and GB virus C/hepatitis G virus infection in individuals with raised liver enzymes but without HBV or HCV infection in Taiwan

The prevalence of TT virus (TTV) and GB virus-C/hepatitis G virus (GBV-C/HGV) infection and the association with raised liver function tests in 546 Taiwanese with negative HBsAg, anti-HCV and HCV RNA was elucidated. They were tested for serum alanine aminotransferase (ALT), GBV-C/HGV RNA, anti-envelope protein 2 antibody (anti-E2) and TTV DNA. Direct sequencing and phylogenetic analyses were performed on 58 isolates for TTV genotype determination. The prevalence of TTV DNA, GBV-C/HGV RNA, anti-E2 and over all GBV-C/HGV exposure was 24.9, 3.4, 8.2 and 11.1%, respectively. Using uni- and multi-variate analyses, male gender and TTV viremia were associated significantly with raised ALT values. Sixty-nine percent of TTV isolates were deduced to be TTV genotype 1 and they had significantly lower mean age than genotype non-1 isolates. In the population, raised ALT may be related to male gender and be attributable to TTV infection but not to GBV-C/HGV among individuals with no evidence of current HBV and HCV infection. TTV genotype 1 is the most prevalent genotype and associated with younger age.     

Biological monitoring of workers exposed to<Emphasis Type="Italic"> N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-dimethylformamide in synthetic leather manufacturing factories in Korea

Objectives To investigate the relationship between N,N-dimethylformamide (DMF) exposure and excretion of urinary N-acetyl-S-(N-methylcarbamoyl)cysteine (AMCC) and N-methylformamide (NMF) in workers at synthetic leather manufacturing factories in Korea, for the first time.Methods One-hundred forty-four male workers at nine synthetic leather manufacturing factories were surveyed. Exposure to DMF was evaluated through breathing zone air sampling followed by analysis via a gas chromatograph equipped with a flame ionization detector (GC-FID). The levels of NMF and AMCC were determined by a GC with a flame thermionic detector (GC-FTD). Urine samples were collected at the end of the workshift.Results and Conclusions Geometric mean of workplace air DMF and urinary NMF was 8.8 ppm and 47.5 mg/l, respectively, and the level of DMF and NMF was significantly correlated. The biological exposure limit for NMF (15 mg/ml) was exceeded in 89.5% of urine samples, and 37.9% of air samples exceeded the environmental DMF exposure limit (10 ppm), indicating a serious health risk to the employees of the synthetic leather industry in Korea. Exposure to 10 ppm DMF in the workplace air corresponded to a urinary NMF concentration of 53.4 mg/l. Alcohol intake the day before urine was sampled influenced NMF excretion into urine (40.5 mg/l NMF for the no-alcohol group and 94.6 mg/l for the group consuming more than 63.0 g alcohol/day). We could not find a significant relationship between air DMF and urinary AMCC concentration. Exposure to 10 ppm DMF corresponded to an AMCC concentration of 8.0 mg/l in the urine samples collected on the same day as the air was sampled.