Hepatic function in workers occupationally exposed to carbon tetrachloride.

OBJECTIVES--To identify any differences in hepatic function between workers exposed to carbon tetrachloride and controls, and to identify the best variable with which to examine any effects. METHODS--In a cross sectional study of hepatic function in workers occupationally exposed to carbon tetrachloride, 135 exposed employees were compared with 276 non-exposed controls. The exposed group was taken from three sites in the north west of England and the control group included non-exposed workers from one of these sites and another site located nearby. Demographic and alcohol consumption data were collected from both groups by questionnaire. Each member of the study group was allotted a notional estimated exposure to carbon tetrachloride, calculated from historic personal monitoring data and job category. A fasting sample of blood was taken from all participants and analysed for a variety of biochemical and haematological variables. The techniques of univariate and multivariate analysis of variance were used to investigate the effect on biochemical and haematological indices of a range of factors. RESULTS--Multivariate analysis of variance of four core liver function variables, alanine transaminase, aspartate transaminase, alkaline phosphatase, and gamma-glutamyl transferase, showed a significant difference between exposed and non-exposed workers. The univariate analyses identified increases in only alkaline phosphatase and gamma-glutamyl transferase within the exposed group and these did not show a significant dose-response relation. Univariate analysis of variance did show effects of alcohol and age on several variables. Significant differences between exposed and control groups for three haematological variables, haemoglobin, packed cell volume, and red blood count, were thought not to be due to the effects of exposure. Clinical review of exposed subjects with abnormal results did not show clinically evident disease that could have been associated with exposure to carbon tetrachloride. Also, a follow up study conducted three years after the cross sectional study at the site with highest exposures to carbon tetrachloride showed no evidence of any further changes in liver function variables. CONCLUSIONS--The most sensitive statistical methods have shown significant differences in the liver function variables measured between people exposed to carbon tetrachloride and the control group. The interpretation of the data collected was that these differences may be due to exposure to carbon tetrachloride but this was not clearly shown. Furthermore, the changes found have not given rise to any clinical disease.     

Respiratory impairment due to asbestos exposure in brake-lining workers

There is extensive evidence that exposure to asbestos causes pulmonary parenchymal fibrosis, pleural disease, and malignant neoplasm in asbestos-exposed workers. However, few data concerning brake-lining workers are available in the literature. In this study, we aimed to assess the long-term effects of chrysotile asbestos exposure on lung function and the risk of asbestos-related diseases in brake-lining workers. Seventy-four asbestos-exposed workers who processed brake-lining products and 12 unexposed office workers were offered pulmonary function tests (spirometry and transfer factor) in 1992 and 1999. In 1999, the mean duration of asbestos exposure was 10.00+/-4.07 and 11.02+/-4.81 years (7-31 years) in nonsmoking and smoking asbestos workers, respectively. Transfer factor (T(L), CO) and transfer coefficient (K(CO)) decline were significant in the 7-year follow-up in both smoking and nonsmoking asbestos workers. However, lung function indices of the control group, whom were all current smokers; were also found to be decreased, including FEF(75), T(L), CO and K(CO). We found minimal reticular changes in 10 asbestos workers who were all current smokers, they underwent high-resolution computed tomography scans of the chest and we found that they had peribronchial thickening resulting from smoking. As a conclusion, even in the absence of radiographic asbestosis, T(L), CO and K(CO) may decrease after a mean 10-year duration of exposure to asbestos in brake-lining workers and this is more noticeable with cigarette burden.     

Respiratory effects of exposure of shipyard workers to epoxy paints

Epoxy resin systems have been associated with occupational asthma in several case reports, but medical publications contain little on the potential adverse respiratory effects of these chemicals in exposed worker populations. To further evaluate the association of workplace exposure to epoxy paints and respiratory dysfunction, the cross workshift changes in pulmonary function and symptoms of 32 shipyard painters exposed to epoxy paints were compared with 28 shipyard painters not exposed to epoxy paints. The prevalence of lower respiratory tract symptoms was significantly higher among painters exposed to epoxy paints compared with controls. Among exposed painters the mean cross workshift change in forced expiratory volume in one second (FEV1) (-3.4%) was greater than the decrement in the non-exposed group (-1.4%). A significant linear relation was seen between % decrement in FEV1 and hours of exposure to epoxy paints. This study suggests that epoxy resin coatings as used by shipyard painters are associated with increased lower respiratory tract symptoms and acute decrements in FEV1. Adequate respiratory protection and medical surveillance programmes should be established in workplaces where exposure to epoxy resin systems occurs.     

饮水中四氯化碳短期暴露健康风险参考值的验证

目的 针对四氯化碳的饮水短期暴露健康参考值的实验验证工作。方法 雄性SD大鼠分为6组（0、10、20、40、80、160 mg/（kg·d））,每组10只,玉米油作为阴性对照组。受试物组灌胃给予CCl4。染毒开始后24 h、11 d各组取5只大鼠,检测血清中OCT、SDH、ALT、AST、BUN。解剖取肝、肾进行组织病理学检查。结果 染毒24 h后,随着染毒剂量的增加,5项血清学指标均呈不同程度升高。大鼠体重、肝肾重及肝肾脏体比与阴性对照组相比均无明显变化。肝脏组织中观察到在80 mg/（kg·d）开始出现空泡。染毒11 d后,5项血清学指标均随着染毒剂量的增加而升高。各剂量组大鼠体重、肾重、肾脏体比与阴性对照组相比,均无明显变化。肝脏组织中观察到在20 mg/（kg·d）开始出现空泡,40 mg/（kg·d）起与对照组相比差异有统计学意义,随着剂量增加空泡病变严重。结论 本实验方案得出1 d的HA值为4 mg/L,10 d的HA值为1 mg/L,其中1 d的HA值与USEPA的相同,10 d的HA值比USEPA的高。     

Respiratory symptoms and ventilatory performance in workers exposed to grain and grain based food dusts

A health surveillance study of male grain food manufacturingworkers used a respiratory health questionnaire and spirometryto assess the prevalence of work-related respiratory symptomsand impaired ventilatory performance. The prevalence of cough,breathlessness, wheeze and chest tightness was between 8–13%but was 20% for rhinitis. Rhinitis was the most common symptomwith 37% of those reporting rhinitis describing this as work-related.A case-control analysis of workers reporting rhinitis did notidentify any specific occupational activities associated withincreased risk of rhinitis. Smoking habit and all respiratorysymptoms apart from rhinitis had a significant effect upon ventilatoryperformance. Occupational exposure to raw grains, flour, ingredientsand finished food was categorized as high, medium or low ineither continuous or intermediate patterns. Multiple regressionanalysis confirmed the effects of height, age and smoking uponventilatory performance. However, occupational exposure to grain,flour, food ingredients and cooked food dusts had no effectupon ventilatory performance. It is concluded that smoking habitis the major determinant of respiratory symptoms and impairedventilatory function. The excess complaints of rhinitis warrantfurther study but it would appear that the current occupationalexposure limits for grain, flour, food ingredients and cookedfood dusts are adequate to protect workers against impairmentof ventilatory performance.     

Respiratory effects of exposure of shipyard workers to epoxy paints.

Epoxy resin systems have been associated with occupational asthma in several case reports, but medical publications contain little on the potential adverse respiratory effects of these chemicals in exposed worker populations. To further evaluate the association of workplace exposure to epoxy paints and respiratory dysfunction, the cross workshift changes in pulmonary function and symptoms of 32 shipyard painters exposed to epoxy paints were compared with 28 shipyard painters not exposed to epoxy paints. The prevalence of lower respiratory tract symptoms was significantly higher among painters exposed to epoxy paints compared with controls. Among exposed painters the mean cross workshift change in forced expiratory volume in one second (FEV1) (-3.4%) was greater than the decrement in the non-exposed group (-1.4%). A significant linear relation was seen between % decrement in FEV1 and hours of exposure to epoxy paints. This study suggests that epoxy resin coatings as used by shipyard painters are associated with increased lower respiratory tract symptoms and acute decrements in FEV1. Adequate respiratory protection and medical surveillance programmes should be established in workplaces where exposure to epoxy resin systems occurs.     

Respiratory and allergic disorders in workers exposed to grain and flour dusts

Symptoms suggestive of chronic bronchitis or chronic productive cough were found in 29.0% of 100 workers exposed to flour dust in a flour mill, 26.0% presenting with chronic cough and 29.0% with phlegm. In the control group, the prevalence of chronic cough and phlegm was only 6.6% in each category. While 22.0% of the workers complained of chest tightness on exposure, and 18.0% developed symptoms and signs of bronchial asthma, only 3.3% of the controls complained of chest tightness and 3.3% of asthma. Respiratory measurements before and after the working shift showed a significant drop (p less than .001) in the forced expiratory volume in 1 sec (FEV1.0) and forced vital capacity (FVC) in the exposed group. Fifty-eight percent of the exposed workers experienced a drop in FEV1.0 and FVC measurements. A positive skin reaction to wheat flour extract was recorded among 31% of the exposed workers vs. 10% of the controls. The prevalence of other associated allergic symptoms was 17.0% and 19.0% for sinusitis and conjunctivitis, respectively; in the unexposed group, the prevalence of the same symptoms ranged between 3.3% and 6.6%. A strong association was revealed between exposure to grain and flour dusts and the prevalence of respiratory and allergic disorders.     

Respiratory cancer risks among workers with glutaraldehyde exposure

OBJECTIVE: Glutaraldehyde is a substance that represents a substantial portion of the human exposure to aldehydes in medicine and industry. Other aldehydes such as formaldehyde have been associated with increased cancer rates of the upper respiratory tract and leukemia. Our study is the only one, to our knowledge, to examine cancer rates among exposed glutaraldehyde workers. METHODS: In an extended follow up using death certificates, we calculated standardized mortality ratios (SMRs) and 95% confidence intervals (CIs) for three cumulative exposure categories of glutaraldehyde. There were 99,730 person-years of observation among unexposed workers, 2934 person-years in the lower exposure category, < 0-100.0 parts per billion (ppb)-years, and 2805 person-years in the higher exposure category of 100.0+ ppb-years. RESULTS: For all respiratory cancers for these exposure categories, the SMRs were 0.9 (95% CI = 0.7-1.1), 1.0 (95% CI = 0.2-3.0), and 0.3 (95% CI = 0.0-1.5). No increasing trend of SMR with increasing exposure is observed for any cause of death examined. We observed no cancers of the nasal cavity and sinus (0.03 expected), nasopharynx (0.02 expected), or leukemia (0.6 expected) among all glutaraldehyde-exposed workers. CONCLUSIONS: Although our study findings should be tempered by the small size and the potentially low prevalence of smoking among glutaraldehyde workers, we found no increased rates of respiratory tract cancer or leukemia related to glutaraldehyde exposure.     

Neuropsychiatric effects in workers with occupational exposure to carbon disulfide

In a cross-sectional study, prevalence of dysfunctions of the central nervous system was assessed in 134 male workers exposed to different levels of carbon disulfide (CS2) in a rayon viscose plant and compared to 38 non-exposed workers. In three groups of workers from the same plant with different levels of CS2 (heavy, intermediate, none) estimated by personal samplers, disorders in the central nervous system were examined by means of psychiatric examination and questionnaire 16 (Q16). Unconditional logistic regression was calculated adjusted for age, alcohol consumption and education. Psychoorganic syndrome was diagnosed significantly more often in workers with heavy CS2 exposure, with adjusted OR of 17.9 (95% CI 2.18-146.73), and insignificantly in workers with intermediate exposure. Prevalence of workers with more than 6 positive answers on the Q16 was higher in the heavily exposed workers (OR=4.76; 95% CI 1.80-12.60). A similar result was found for almost all the questions in the Q16, and the most pronounced psychological symptom was of less interest in sex (adjusted OR=8.14; 95% CI 2.19-30.22). High correlation was found between symptoms recorded on neuropsychiatric examination and on Q16. Both neuropsychiatric exams and Q16 indicated disturbances in the central nervous system due to the long-term heavy exposure to CS2. Disorders of the central nervous system were found more often in workers with heavy exposure to CS2. Questionnaire Q16 is a valuable means for selecting workers for further neuropsychiatric testing.     

Chronic peripheral neuropathy in workers with previous exposure to carbon disulphide.

Two groups of viscose rayon production workers were examined 10 years after discontinuation of exposure to CS2. Group A comprised 20 subjects exposed to high CS2 concentrations and group B 13 subjects with lower exposure. Clinical findings and the measurements of nerve conduction velocity of the slow fibres in the peripheral nerves were evaluated. Twelve subjects had both clinical and electromyographic evidence of neuropathy and 10 showed a diminution in motor conduction velocity. A relationship between the degrees of exposure to CS2 and prevalence of polyneuropathy was found. On re-examining 12 subjects with neuropathy who had been examined four years before no significant electromyographic improvement was observed. These findings are consistent with a permanent axonal neuropathy caused by carbon disulphide.     

Dust exposure in workers from grain storage facilities in Costa Rica

Background

About 12 million workers are involved in the production of basic grains in Central America. However, few studies in the region have examined the occupational factors associated with inhalable dust exposure.

Respiratory symptoms and lung function following exposure in workers exposed to soft paper tissue dust

Summary The objective of this study was to investigate if the dust in a mill producing soft paper tissue caused respiratory symptoms or impaired respiratory function. Using a questionnaire and spirometry, 355 persons were examined. They were divided into three groups according to present exposure to dust; low (< 1 mg/m³), moderate (1–5 mg/m³) and heavy (> 5 mg/m³). There was a dose-dependent increase of symptoms from the upper respiratory tract. However, coughing and coughing with phlegm were not found to be more common among persons with heavy exposure compared to those with low exposure to the dust. There was no difference in FEV, or FVC during a work shift. Persons with long-term (> 10 years) and heavy exposure to dust seemed to have impaired respiratory function compared to those with low and/or short-term exposure to the dust.     

Respiratory health effects of carbon black: a survey of European carbon black workers.

A study population of 3086 employees was identified in 18 carbon black production plants in seven European countries. Respiratory health questionnaires, spirometry, and chest radiographs were used to estimate effects on health and personal monitoring procedures were employed to measure current exposure to inspirable and respirable dust along with sulphur and carbon monoxide. The low concentrations of gaseous contaminants made the generation of their current and cumulative exposure indices impossible. Low responses from some plants restricted the final analysis to 1742 employees in 15 plants (81% response rate) for respiratory symptoms and spirometry, and 1096 chest radiographs from 10 plants (74% response rate). In total, 1298 respirable and 1317 inspirable dust samples, as well as 1301 sulphur dioxide and 1322 carbon monoxide samples were collected. This study is the first to include a comprehensive and concurrent assessment of occupational exposure to carbon black dust and its associated gaseous contaminants. Cough, sputum, and the symptoms of chronic bronchitis were found to be associated with increasing indices of current exposure. Lung function tests also showed small decreases in relation to increasing dust exposure in both smokers and non-smokers. Nearly 25% of the chest radiographs showed small opacities of category 0/1 or greater. These were strongly associated with indices of cumulative dust exposure. The findings are consistent with a non-irritant effect of carbon black dust on the airways combined with dust retention in the lungs. Further cross sectional studies are planned to investigate whether long term exposure to carbon black dust causes damage to the lung parenchyma.