Biomedical subjects

Julius Mwaiselage

Publications and source records attributed to Julius Mwaiselage.

6 recordsLinked to original sources

PubMed2006

Variability of exposure and estimation of cumulative exposure in a manually operated coal mine.

This study aims at estimating variability in exposure to respirable dust and assessing whether the a priori grouping by job team is appropriate for an exposure-response study on respiratory effects among workers in a manually operated coal mine in Tanzania. Furthermore, estimated exposure levels were used to calculate cumulative exposure. Full-shift personal respirable dust samples (n = 204) were collected from 141 randomly chosen workers at underground and surface work sites. The geometric mean exposure for respirable dust varied from 0.07 mg m(-3) for office workers to 1.96 mg m(-3) for the development team. The analogous range of respirable quartz exposure was 0.006-0.073 mg m(-3). Variance components were estimated using random effect models. For most job teams the within-worker variance component was considerably higher than the between-worker variance component. For respirable dust the estimated attenuation of the linear exposure-response relationship was low (5.9%) when grouping by job team. Grouping by job team was considered appropriate for studying the association between current dust exposure and respiratory effects. Based on the estimated worker-specific mean exposure in the job teams, the arithmetic mean cumulative exposure for the 299 workers who participated in the epidemiological part of the study was 38.1 mg* yr m(-3) for respirable dust and 2.0 mg* yr m(-3) for quartz.

Adult↗

PubMed2005

High exposure to respirable dust and quartz in a labour-intensive coal mine in Tanzania.

Labour-intensive mines are numerous in several developing countries, but dust exposure in such mines has not been adequately characterized. The aim of this study was to identify and quantify the determinants of respirable dust and quartz exposure among underground coal mine workers in Tanzania. Personal respirable dust samples (n = 134) were collected from 90 underground workers in June-August 2003 and July-August 2004. The development team had higher exposure to respirable dust and quartz (geometric means 1.80 and 0.073 mg m(-3), respectively) than the mining team (0.47 and 0.013 mg m(-3)), the underground transport team (0.14 and 0.006 mg m(-3)) and the underground maintenance team (0.58 and 0.016 mg m(-3)). The percentages of samples above the threshold limit values (TLVs) of 0.9 mg m(-3) for respirable bituminous coal dust and 0.05 mg m(-3) for respirable quartz, respectively, were higher in the development team (55 and 47%) than in the mining team (20 and 9%). No sample for the underground transport team exceeded the TLV. Drilling in the development was the work task associated with the highest exposure to respirable dust and quartz (17.37 and 0.611 mg m(-3), respectively). Exposure models were constructed using multiple regression model analysis, with log-transformed data on either respirable dust or quartz as the dependent variable and tasks performed as the independent variables. The models for the development section showed that blasting and pneumatic drilling times were major determinants of respirable dust and quartz, explaining 45.2 and 40.7% of the variance, respectively. In the mining team, only blasting significantly determined respirable dust. Immediate actions for improvements are suggested to include implementing effective dust control together with improved training and education programmes for the workers. Dust and quartz in this underground mine should be controlled by giving priority to workers performing drilling and blasting in the development sections of the mine.

Coal Mining↗

PubMed2005

Acute respiratory health effects among cement factory workers in Tanzania: an evaluation of a simple health surveillance tool.

OBJECTIVES: The effects of cement dust exposure on acute respiratory health were assessed among 51 high exposed and 33 low exposed male cement workers. The ability of the questionnaire to diagnose acute decrease in ventilatory function was also assessed. METHODS: Acute respiratory symptoms were recorded by interview using a structured optimal symptom score questionnaire. Peak expiratory flow (PEF) was measured preshift and postshift for each worker with a Mini-Wright PEF meter. Personal respirable dust (n=30) and total dust (n=15) were measured with 37-mm Cyclone and 37-mm closed-faced Millipore cassette. Twenty-nine workers had concurrent respirable dust, PEF and questionnaire on the same day. RESULTS: The geometric means of personal respirable dust and total dust among high exposed were 4.0 and 13.2 mg/m(3), respectively, and 0.7 and 1.0 mg/m(3) among low exposed. High exposed workers had more acute cough, shortness of breath and stuffy nose than the low exposed. Mean percentage cross-shift decrease in PEF was significantly more pronounced among high exposed workers than low exposed (95% CI 1.1, 6.1%). For workers with concurrent respirable dust, PEF and questionnaire assessment, an exposure-response relationship was found between log-transformed respirable dust and percentage cross-shift decrease in PEF (4.5% per unit of log-respirable dust in mg/m(3) ; 95% CI 3.3, 5.6%). Respirable dust exposure >/=2.0 mg/m(3) versus <2.0 mg/m(3) was associated with increased prevalence ratio for cough (7.9) and shortness of breath (4.2). Shortness of breath was associated with the highest sensitivity (0.87) and specificity (0.83) for diagnosing a percentage cross-shift decrease in PEF of >/=10%. CONCLUSION: The observed acute respiratory health effects among the workers are most likely due to exposure to high concentrations of irritant cement dust. The results also highlight the usefulness of the questionnaire for health surveillance of the acute respiratory health effect.

Acute Disease↗

PubMed2005

Variability in dust exposure in a cement factory in Tanzania.

Dust exposure levels were studied in a cement factory in Dar es Salaam, Tanzania, as part of an epidemiological study assessing chronic respiratory health effects. One hundred and twenty personal 'total' dust samples were collected from 80 randomly selected workers from eight a priori occupational groups (OGs) based on work areas using a 37 mm Millipore sampler. The between-group, within-group and within-worker variances were determined to assess the contrast in exposure level between the OGs and to estimate the attenuation and standard error of the theoretical exposure-response slope. Using mixed-effect model estimates, the probability of overexposure relative to the occupational exposure limit (OEL) was assessed for each OG. The geometric means of total dust exposure were higher in the cranes (38.64 mg m(-3)), packing (21.30 mg m(-3)) and crusher (13.48 mg m(-3)) than in the cement mill (3.23 mg m(-3)), kiln (2.87 mg m(-3)), raw mill (1.85 mg m(-3)), maintenance (1.16 mg m(-3)) and administration (0.29 mg m(-3)). The a priori grouping scheme seems to be an efficient scheme because of the high contrast in exposure level between the OGs (0.78) and minimal attenuation of the theoretical exposure-response slope (1.0%). When using the reduced mixed-effect model, the probabilities of overexposure () relative to the OEL of 10 mg m(-3) for total cement dust were higher in the crane (96%), packing (88%) and crusher (73%) than in the cement mill (16%), kiln (14%), raw mill (5%), maintenance (2%) and administration (0.01%).

Construction Materials↗

PubMed2005

Respiratory symptoms and chronic obstructive pulmonary disease among cement factory workers.

OBJECTIVES: This study assessed chronic respiratory symptoms and chronic obstructive pulmonary disease (COPD) among workers exposed to cement dust at a Tanzanian cement factory. METHODS: A total of 120 exposed workers and 107 controls participated in this cross-sectional investigation. Information on demographics, occupational history, chronic respiratory symptoms, smoking habits, and use of respiratory protection equipment was collected by questionnaire. Ventilatory function testing and measurement of personal total dust exposure were also carried out. COPD was diagnosed for workers with chronic bronchitis who also had spirometric airflow obstruction. Chronic respiratory symptoms and COPD were correlated with cumulative total dust exposure and adjusted for age, pack-years, and education. RESULTS: The exposed workers had more chronic cough [odds ratio (OR) 4.5, 95% confidence interval (95% CI) 1.9-10.4], chronic sputum production (OR 10.8, 95% CI 4.4-26.4.), dyspnea (OR 5.3, 95% CI 1.9-15.2), work-related shortness of breath (OR 4.8, 95% CI 1.6-14.2), and chronic bronchitis (OR 5.5, 95% CI 2.0-15.3) than the controls. Chronic cough, chronic sputum production, dyspnea, work-related shortness of breath, and chronic bronchitis were significantly related to cumulative dust exposure of 20.0-99.9 and > or = 100.0 versus <20.0 mg/m3-years. The prevalence of COPD was higher for the exposed group (18.8%) than for the controls (4.8%). The odds ratio for COPD was significantly increased for cumulative dust exposure, > or = 100.0 versus <20.0 mg/m3-years (OR 11.2, 95% CI 2.2-56.0). CONCLUSIONS: Cement workers seem to be at high risk of developing chronic respiratory symptoms and COPD, probably caused by cumulative total dust exposure independent of smoking habits.

Age Factors↗

PubMed2004

Cement dust exposure and ventilatory function impairment: an exposure-response study.

We investigated cumulative total cement dust exposure and ventilatory function impairment at a Portland cement factory in Tanzania. All 126 production workers were exposed. The control group comprised all 88 maintenance workers and 32 randomly chosen office workers. Exposed workers had significantly lower forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), peak expiratory flow rate (PEF), FEV1/FVC, FVC%, FEV1% and PEF%, than controls adjusted for age, duration of employment, height, and pack-years. Cumulative total dust exposure was significantly associated with reduced FVC, forced expiratory volume in 1 second, and peak expiratory flow rate adjusted for age, height and pack-years. Cumulative total dust exposure more than 300 mg/m year versus lower than 100 mg/m years was significantly associated with increased risk of developing airflow limitation (odds ratio = 9.9). The current occupational exposure limit for total cement dust (10 mg/m) appears to be too high to prevent respiratory health effects among cement workers.

Adult↗