Assessment of historical exposures in a nickel refinery in Norway. (25/621)

OBJECTIVES: The aim of the study was, on the basis of new information on nickel species and exposure levels, to generate a specific exposure matrix for epidemiologic analyses in a cohort of Norwegian nickel-refinery workers with a known excess of respiratory cancer. METHODS: A department-time-exposure matrix was constructed with average exposure to total nickel estimated as the arithmetic mean of personal measurements for periods between 1973 and 1994. From 1972 back to the start of production in 1910, exposure concentrations were estimated through retrograde calculation with multiplication factors developed on the basis of reported changes in the metallurgical process and work environment. The relative distribution of water-soluble nickel salts (sulfates and chlorides), metallic nickel, and particulates with limited solubility (sulfides and oxides) was mainly derived from speciation analyses conducted in the 1990s. RESULTS: The average concentration of nickel in the breathing zone was < or = 0.7 mg/m3 for all workers after 1978. Exposure levels for smelter and roaster day workers were 2-6 mg/m3 before 1970, while workers in nickel electrolysis and electrolyte purification were exposed to concentrations in the range of 0.15-1.2 mg/m3. The level of water-soluble nickel was of the same order for workers in the smelting and roasting departments as in some of the electrolyte purification departments. CONCLUSIONS: Compared with earlier estimates, the present matrix probably offers a more reliable description of past exposures at the plant.  (+info)

Factors predictive of ischemic heart disease mortality in foundry workers exposed to carbon monoxide. (26/621)

The potential predictors of ischemic heart disease mortality were studied for 931 male foundry workers in Finland who participated in a health examination in 1973. These workers were followed up to 1993 through registers and by using a questionnaire. In 1973, the systolic and diastolic blood pressures of workers exposed to carbon monoxide (CO) were slightly higher than those of unexposed workers. The prevalence of angina pectoris showed a clear dose-response relation to CO exposure. Electrocardiogram (ECG) findings indicating past myocardial infarction or suggesting coronary artery disease as a function of smoking and/or CO exposure were not evident. In the 1987 follow-up, the rate ratio for ischemic heart disease mortality was estimated as 4.4 for CO-exposed smokers compared with unexposed nonsmokers. Ischemic heart disease mortality in 1973-1993 was analyzed by using the Cox proportional hazards model. The statistically significant predictors were age, pathologic ECG findings in 1973, regular CO exposure, and abundant alcohol drinking. Of the ECG findings, changes in Q or QS and ST-J or ST waves and in ventricular extrasystoles were statistically significant. The risk of mortality from ischemic heart disease was increased by working in iron foundries, by hypertension, and by smoking.  (+info)

Impact of occupation on respiratory disease. (27/621)

OBJECTIVES: This study identified occupations with a marked impact on sick leaves due to respiratory disease. METHODS: A national sick-leave register containing information on all sick leaves exceeding 14 days, physicians' diagnoses, and the occupational status of all manual and service employees in the private sector in Sweden was studied. Sick leaves during 1992-1994 (N=210,755) were analyzed with special attention to respiratory disease and occupation. RESULTS: Respiratory disease accounted for 4.4% of the total number of sick leaves. The incidence of long-term (> or = 90 days) sick leaves due to respiratory disease was 3 times higher in occupations with a high incidence than in those with a low incidence. There was a high correlation (r=0.80) between the incidence of long-term sick leave due to respiratory disease and sick leave due to all other conditions; this finding suggests that market and selection factors may play an important role in determining the overall risk for sick leave in various occupations. The proportion of sick leaves due to long-term respiratory disease out of all long-term disease was compared between occupations. Agricultural workers had a 46% higher proportion of long-term respiratory disease than metal workers. Industrial workers, food industry workers, and painters were also occupations with an increased risk. These findings could not be explained by differences in age or smoking habits. CONCLUSIONS: Major differences were found among manual and service occupations regarding long-term sick leave due to respiratory disease. Several occupations, in which exposure to respiratory sensitizers and irritants are known to occur, were among those in which workers had an increased risk for long-term respiratory disease.  (+info)

Predictors of DMSA chelatable lead, tibial lead, and blood lead in 802 Korean lead workers. (28/621)

OBJECTIVES: To examine the interrelations among chelatable lead (by dimercaptosuccinic acid, DMSA), tibial lead, and blood lead concentrations in 802 Korean workers with occupational exposure to lead and 135 employed controls with only environmental exposure to lead. METHODS: This was a cross sectional study wherein tibial lead, DMSA chelatable lead, and blood lead were measured. Linear regression was used to identify predictors of the three lead biomarkers, evaluating the influence of age, job duration, sex, education level, alcohol and tobacco use, creatinine clearance rate, and body mass index. RESULTS: DMSA chelatable lead concentrations ranged from 4.8 to 2102.9 microg and were positively associated with age, current smoking, and creatinine clearance rate. On average, women had 64 microg less DMSA chelatable lead than men. When blood lead and its square were added to a model with age, sex, current smoking, body mass index, and creatinine clearance rate, blood lead accounted for the largest proportion of the variance and sex became of borderline significance. Tibial lead concentrations ranged from -7 to 338 microg/g bone mineral and were positively associated with age, job duration, and body mass index. Women had, on average, 9.7 microg/g less tibial lead than men. Blood lead concentrations ranged from 4.3 to 85.7 microg/dl and were positively associated with age and tibial lead, whereas current smokers had higher blood lead concentrations and women had lower blood lead concentrations. CONCLUSIONS: The data suggest that age and sex are both predictors of DMSA chelatable lead, blood lead, and tibial lead concentrations and that tibial lead stores in older subjects are less bioavailable and may contribute less to blood lead concentrations than tibial lead stores in younger subjects. Although blood lead concentrations accounted for a large proportion of the variance in DMSA chelatable lead concentrations, suggesting that measurement of both in epidemiological studies may not be necessary, the efficacy of each measure in predicting health outcomes in epidemiological studies awaits further investigation.  (+info)

Mercury evaporation from amalgams with varied mercury contents. (29/621)

This study examined the relationship between mercury content and mercury evaporation from amalgams during setting. Two different types of commercial high-copper amalgams (single composition and admixed types) were used. Cylindrical specimens of each amalgam were prepared with five different mercury contents according to ADA Specification No.1. Specimens were also prepared by hand condensation. Mercury evaporation from amalgam specimens maintained at 37 degrees C was measured using a gold film mercury analyzer from 10 min after the end of trituration until the mercury concentration in air reached an undetectable level. The mercury content more clearly influenced the mercury evaporation from the admixed type amalgam specimens when the mercury content decreased below the manufacturers' recommended trituration conditions. Triturating with less mercury than the manufacturers' recommended amount cannot lower the evaporation of mercury from freshly made amalgam. Proper condensing procedures can minimize the mercury evaporation from the amalgam surface.  (+info)

Development of Ag-Pd-Au-Cu alloy for multiple dental applications. Part 1. Effects of Pd and Cu contents, and addition of Ga or Sn on physical properties and bond with ultra-low fusing ceramic. (30/621)

Ag-Pd-Au-Cu quaternary alloys consisting of 30-50% Ag, 20-40% Pd, 10-20% Cu and 20% Au (mother alloys) were prepared. Then 5% Sn or 5% Ga was added to the mother alloy compositions, and another two alloy systems (Sn-added alloys and Ga-added alloys) were also prepared. The bond between the prepared alloys and an ultra-low fusing ceramic as well as their physical properties such as the solidus point, liquidus point and the coefficient of thermal expansion were evaluated. The solidus point and liquidus point of the prepared alloys ranged from 802 degrees C to 1142 degrees C and from 931 degrees C to 1223 degrees C, respectively. The coefficient of thermal expansion ranged from 14.6 to 17.1 x 10(-6)/degrees C for the Sn- and Ga-added alloys. In most cases, the Pd and Cu contents significantly influenced the solidus point, liquidus point and coefficient of thermal expansion. All Sn- and Ga-added alloys showed high area fractions of retained ceramic (92.1-100%), while the mother alloy showed relatively low area fractions (82.3%) with a high standard deviation (20.5%). Based on the evaluated properties, six Sn-added alloys and four Ga-added alloys among the prepared alloys were suitable for the application of the tested ultra-low fusing ceramic.  (+info)

How a sample of businesses in the West Midlands (UK) are currently managing vibration exposure. (31/621)

This paper discusses the results of a local initiative in the West Midlands (UK) which looked at how businesses in engineering, utilities and foundry trades managed the risks from hand-arm vibration. Inadequacies of health surveillance programmes and the need for enforcement action are outlined.  (+info)

Prognostic factors for respiratory sickness absence and return to work among blue collar workers and office personnel. (32/621)

OBJECTIVES: To analyze factors that determine the occurrence of sickness absence due to respiratory disorders and the time it takes to return to work. METHODS: A longitudinal study with 2 year follow up was conducted among 326 male blue collar and white collar workers. The survey started with an interview on respiratory complaints and spirometry. Sixty six (21%) workers were lost to follow up. Complete data on sickness absence among 251 workers during the follow up were collected from absence records and self reports. Regression analysis based on a proportional hazards model was applied to identify risk factors for the occurrence and duration of sickness absence due to respiratory disorders. RESULTS: During the follow up 35% workers attributed at least one period of sickness absence to respiratory complaints, which accounted for 14.2% of all days lost. A history of chronic obstructive pulmonary disease (COPD) did not predict sickness absence for COPD; the same was true for chronic non-specific lung disease (CNSLD). Complaints about asthma contributed significantly to absence due to asthma (relative risk (RR) 3.96; 95% confidence interval (95% CI) 1.99 to 7.90). Job title was a significant predictor of sickness absence due to respiratory complaints. Decrease in forced vital capacity (FVC, <80% of the reference value) was also a significant predictor of absence due to asthma (RR 4.03; 95% CI 1.41 to 11.54) and of respiratory absence (RR 2.49; 95% CI 1.07 to 5.79). Absence with respiratory complaints was not associated with age, height, body mass index, or smoking. Duration of employment was a weak almost significant predictor against respiratory absenteeism (RR 0.94; 95% CI 0.91 to 0.97). Return to work after respiratory absence was worse for blue collar workers than office personnel (RR 5.74; 95% CI 1.90 to 17.4 for welders, and RR 6.43; 95% CI 2.08 to 19.85 for metal workers). CONCLUSIONS: Asthmatic complaints in the 12 months before the study were associated with sickness absence for these complaints during the follow up. An abnormal level of FVC also influenced respiratory absenteeism. Blue collar workers had more often and more prolonged absences due to respiratory disorders than white collar workers. Workers with absence due to respiratory complaints were at higher risk of subsequent sickness absence in the next year.  (+info)