Laboratory Results of Some Biological Measures in Workers Exposed to Lead

Erythrocyte ALA-dehydratase (ALAD) activity and blood lead levels were studied in different groups of subjects not occupationally exposed to lead, ie, male and female clerical workers, traffic policemen, motorway tollgate attendants, and chronic alcoholics in comparison with values obtained in workers in a lead- using industry.

Among the subjects without occupational exposure to lead, the highest mean values of erythrocyte ALAD activity and the lowest mean values of lead in the blood were found in female clerical workers. Progressively lower mean values of ALAD activity and conversely higher mean values of lead in the blood were observed in the male clerical workers, traffic policemen, motorway tollgate attendants, and chronic alcoholics.

In workers occupationally, exposed to lead, erythrocyte ALAD activity undergoes much greater reductions not only in the manifest phases of lead poisoning but even at the very beginning of exposure, and ALAD remains reduced even some time after exposure has ceased.     

Retrospective exposure assessment for respirable and inhalable dust, crystalline silica and arsenic in the former German uranium mines of SAG/SDAG Wismut

OBJECTIVES: Starting shortly after the reunification of Germany and lasting up to the end of the 1990s, an extensive series of retrospective exposure investigations for the East German uranium mining industry was performed in order to provide information about the exposure situation of the miners towards respirable dust, inhalable dust, crystalline silica and heavy metals. It should provide the necessary information for legal compensation of miners with potential industrial diseases as well as for epidemiological research. METHODS: Extensive side-by-side measurements using original historic equipments as well as comprehensive evaluation of the time increments of specific jobs with respect to exposure relevant tasks were performed. After attributing average exposures to the tasks, shift exposures for the jobs could be calculated. RESULTS: By the end a comprehensive job exposure matrix for all underground jobs of the German uranium mining industry was developed for the components mentioned, including arsenic where relevant. In the early days of SAG/SDAG Wismut dust and silica exposures were extremely high with respirable dust up to 20 mg/m(3) and respirable crystalline silica well above 2 mg/m(3) as shift averages. Beginning from about the early 1960s dust control measures started to improve conditions dramatically. CONCLUSIONS: It is absolutely necessary to invest sufficient effort for the estimation of exposure situations of past technological environments. Especially, the situation of early mechanised mining, characterised by low ventilation, dry drilling techniques and generally lacking dust control measures was characterized by extreme shift exposures. It is important to keep these in mind when metal mining exposure in different environments is considered.     

蔺草染土粉尘的特性及职业危害

目的　研究蔺草染土粉尘的特性及其对作业场所环境污染的特点。方法　按GB5 74 8— 85和GB16 2 2 5— 1996规定的方法在同一作业点同时测定总粉尘和呼吸性粉尘浓度 ;分别用焦磷酸重量法和X射线衍射法测定粉尘中游离SiO2 含量 ,X射线衍射法测定粉尘矿物学结构。结果　总粉尘浓度几何均数为(2 7 90± 2 82 )mg/m3 ,呼吸性粉尘浓度几何均数为 (6 78± 2 5 2 )mg/m3 ,两者呈正相关 ,r =0 873,P <0 0 1,两种粉尘浓度均数的比值为 4 11;X射线衍射法测定总粉尘和呼吸性粉尘中游离SiO2 含量分别为 4 5 87%和 2 1 37% ;构成染土粉尘的矿物主要有石英、高岭土、叶腊石、云母。结论　蔺草染土是一种混合性矿物粉尘 ,其中呼吸性粉尘约占 2 5 % ;由于环境中粉尘浓度很高 ,长期接触可引起尘肺 ,多种矿物的联合作用不可忽视     

A comprehensive assessment of exposures to respirable dust and silica in the taconite mining industry

This study assessed the present-day levels (year 2010–2011) of exposure to respirable dust (RD) and respirable silica (RS) in taconite mines and evaluated how the mining process influences exposure concentrations. Personal samples (n = 679) were collected to assess exposure levels of workers to RD and RS at six mines in the Mesabi Iron Range of Minnesota. The RD and RS concentrations were measured using the National Institute for Occupational Safety and Health (NIOSH) 0600 and NIOSH 7500, respectively. Between-mine, between-SEG (similar exposure groups), within-SEG, and within-worker components of variability for RD and RS exposures were estimated using a two- or three-way nested random-effects ANOVA model. The majority of RD concentrations across all mines were below the Mine Safety and Health Administration (MSHA) Permissible Exposure Limit (PEL). The highest concentrations of RD were often observed in either the Pelletizing or Crushing departments, which are inherently dusty operations. With a few exceptions, the concentrations of RS in the crushing and concentrating processes were higher than those in the other mining processes, as well as higher than the American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV) for RS. The magnetic separation and flotation processes in the concentrating department reduced the levels of RS significantly, and lowered the percentage of quartz in RD in the pelletizing department. There was little variability among the six mines or between the two mineralogically distinct zones for either RD or RS exposures. The between-SEG variability for RS did not differ substantially across most of the mines and was a major component of exposure variance. The within-SEG (or between-worker) variance component was typically the smallest because in many instances one worker from a SEG within a mine was monitored multiple times. Some of these findings were affected by the degree of censoring in each SEG and mine, characteristics of the taconite rock, seasonal effects during sampling, or the tasks assigned to each job in that mine.     

呼吸性矽尘与矽肺的暴露——反应关系

本文在某钨矿进行了呼吸性矽尘与矽肺的暴露～反应关系的研究。首先对该矿井下呼吸性粉尘与息扮尘浓度的关系进行了研究,把历史接尘资料中总粉尘浓度转换为呼吸性粉尘浓度。最后用Logistic多元回归模型对1151名工人的接尘资辩进行了处理,推算出在一定接尘条件下,呼吸性矽尘的容许浓度为0.24mg/m~3。     

Silica exposure and silicosis among Ontario hardrock miners: III. Analysis and risk estimates

An epidemiological investigation was undertaken to determine the relationship between silicosis in hardrock miners in Ontario and cumulative exposure to silica (free crystalline silica--alpha quartz) dust. This report describes the analytic method and presents the risk estimates.     

红外光谱法与焦磷酸消化法测定粉尘中游离二氧化硅含量的比较

目的比较红外光谱法与焦磷酸消化法测定粉尘中游离二氧化硅的可行性。方法对粉尘中游离二氧化硅含量用上述2种方法分别进行测定,比较2种方法测定结果。结果红外光谱法与焦磷酸消化法测定游离二氧化硅含量值差异无统计学意义（P〉0.05）,游离二氧化硅含量在0～100.03 mg范围内与吸光度值有良好的线性关系,相关系数r=0.9996。样品加标回收率为93.08%～95.01%,测定结果的相对标准偏差不大于5.21%（n=5）。结论红外光谱法可以实现高精度快速批量检测,可以逐步取代焦磷酸消化法。     

Silica exposure and silicosis among Ontario hardrock miners: II. Exposure estimates

An epidemiological investigation was carried out to determine the relationship between silicosis in hardrock miners in Ontario and cumulative exposure to silica (free crystalline silica--alpha quartz) dust. This second report describes a side-by-side air-sampling program used to derive a konimeter/gravimetric silica conversion curve. A total of 2,360 filter samples and 90,000 konimeter samples were taken over 2 years in two mines representing the ore types gold and uranium, both in existing conditions as well as in an experimental stope in which dry drilling was used to simulate the high dust conditions of the past. The method of calculating cumulative respirable silica exposure indices for each miner is reported.     

X线衍射法与焦磷酸消化法测定粉尘中游离二氧化硅含量的比较

对粉尘中游离二氧化硅含量进行了Ｘ线衍射法和焦磷酸消化法的对比测定。结果表明,Ｘ线衍射法与焦磷酸地的结果之间有很好的相关性,其测定值在统计学上无显著性差异（Ｐ〉０．０５）,两方法测定值的相关回归方程是Ｙ＝１．０００９Ｘ＋２．２６２６,ｒ＝０．９７１９。Ｘ线衍射法的相对偏差小于１０％,达到常规微量（０．１～５ｍｇ）样本的分析要求;可以较好地排除某些干扰因子对结果的影响。     

Exposure-response relationships for coal mine dust and obstructive lung disease following enactment of the Federal Coal Mine Health and Safety Act of 1969.

Underground U.S. coal miners were studied cross-sectionally for the association of respirable coal mine dust exposure with pulmonary function and symptoms of airways obstruction. The study group included 1,185 miners participating in Round 4 of the National Study of Coal Workers' Pneumoconiosis who had started mining in or after 1970 when comprehensive exposure regulations first came into effect. Quantitative estimates of cumulative exposure, derived using respirable dust measurements taken by the Mine Safety and Health Administration over the entire study period, were used in linear and logistic regression models on indicators of pulmonary function and chest symptoms while controlling for smoking status, pack-years, and other potential confounders. Statistically significant associations between log cumulative exposure and decrements in FVC, FEV1, and FEV1/FVC were observed. In logistic models, statistically significant associations of cumulative exposure with increasing prevalence of FEV1 and FEV1/FVC less than 80% predicted and symptoms including chronic phlegm, chronic bronchitis, breathlessness, wheeze, and wheeze with shortness of breath were found. It is concluded that exposures to respirable coal mine dust present in U.S. mines since 1970 continue to affect respiratory health in underground miners.     

15 years of monitoring occupational exposure to respirable dust and quartz within the European industrial minerals sector

Introduction

In 2000, a prospective Dust Monitoring Program (DMP) was started in which measurements of worker’s exposure to respirable dust and quartz are collected in member companies from the European Industrial Minerals Association (IMA-Europe). After 15 years, the resulting IMA-DMP database allows a detailed overview of exposure levels of respirable dust and quartz over time within this industrial sector. Our aim is to describe the IMA-DMP and the current state of the corresponding database which due to continuation of the IMA-DMP is still growing. The future use of the database will also be highlighted including its utility for the industrial minerals producing sector.

Respirable Dust and Respirable Silica Exposure in Ontario Gold Mines

A comprehensive survey of respirable dust and respirable silica in Ontario gold mines was conducted by the Ontario Ministry of Labor during 1978–1979. The aim was to assess the feasibility of introducing gravimetric sampling to replace the assessment method which used konimeters, a device which gave results in terms of number of particles per cubic centimeter (ppcc) of air. The study involved both laboratory and field assessments. The field assessment involved measurement of airborne respirable dust and respirable silica at all eight operating gold mines of the time. This article describes the details of the field assessment. A total of 288 long-term (7–8 hr) personal respirable dust air samples were collected from seven occupational categories in eight gold mines. The respirable silica (α-quartz) was determined by x-ray diffraction method. The results show that during 1978–1979, the industry wide mean respirable dust was about 1 mg/m³, and the mean respirable silica was 0.08 mg/m^3.The mean% silica in respirable dust was 7.5%. The data set would be useful in future epidemiological and health studies, as well as in assessment of workers’ compensation claims for occupational diseases such as silicosis, chronic obstructive pulmonary disease (COPD), and autoimmune diseases such as renal disease and rheumatoid arthritis.     

Respirable silica and noise exposures among stone processing workers in northern Thailand

Silica and noise are highly prevalent occupational exposures in the stone processing industry. Monitoring for silica and noise are expensive tasks that may be especially difficult to perform in low-resource settings, but exposure awareness is vital for protecting worker health. This study evaluated personal noise and silica measurements at a stone processing facility in northern Thailand to investigate the differing exposure potentials and risk for overexposure among the varying job categories. Our research team performed repeated personal noise and respirable silica measurements on 46 workers, over three separate workshifts for each of 46 workers. While 36.2% of noise measurements exceeded the recommended exposure limit of 85 dBA, only three silica measurements (2.4%) were above the threshold limit value (TLV) of 25 µg/m³. Self-reported personal protective equipment use was low, with only 27.5% of participants wearing hearing protection in noisy environments during their monitored shift and 29.7% of workers wearing respiratory protection during dusty portions of their shift. We identified a significant positive correlation between measured noise and silica levels (r = 0.54, p < 0.01), with stone loaders having the highest average noise (mean = 89 dBA, standard deviation = 4.9 dBA) and silica (geometric mean = 6.4 µg/m³, geometric standard deviation = 1.8) exposure levels. In a multivariate model, the stone loader job category was a significant predictor of exposure to detectable levels of respirable silica (p < 0.01). These results provide useful guidance regarding the need for noise and silica exposure interventions in order to reduce incidences of workplace disease in the stone processing industry.     

Silica exposure and silicosis among Ontario hardrock miners: I. Methodology

An epidemiological investigation was undertaken to determine the relationship between silicosis in hardrock miners in Ontario and cumulative exposure to silica (crystalline silica--alpha quartz) dust. This first report describes the cohort, the method of classifying the radiographs, and the identification of a case of silicosis.     

The accuracy of self-reported regulatory data: the case of coal mine dust

Coal-mine owners are required to measure miner exposures to respirable dust so that compliance with Federal health regulations can be monitored. This study analyzes the problem of possible underreporting of dust exposures. Using two statistical approaches, data for three mining occupations in 54 large underground coal mines during 1976-1978 are examined for evidence of underreporting. First, regression estimates compare dust concentrations reported by coal-mine owners with those reported by government health inspectors. Then, the statistical distribution of concentrations reported by coal-mine owners are examined for the size and nature of their deviation from log-normality. Both approaches suggest widespread underreporting.     

The incidence and progression of pneumoconiosis over nine years in U.S. coal miners: I. Principal findings

Chest radiographs, taken at a 9-year interval for 1,261 U.S. coal miners, were read for pneumoconiosis side-by-side by six readers in a controlled trial. Incidence and progression of small, rounded opacities were consistent with levels predicted from dose-response curves developed by the British Pneumoconiosis Field Research interpolated at a concentration derived from U.S. compliance levels mandated over the last 9 years. The results imply that the level of pneumoconiosis in U.S. miners is being reduced through application of the current 2 mg/m3 standard. The long developmental period for pneumoconiosis necessitates that further study be undertaken to verify this finding and to determine whether 2 mg/m3 is an appropriate regulatory dust level for the prevention of category 2 or greater simple pneumoconiosis over a 35-year period.