Effects of exposure to grain dust on pulmonary function of selected animal feed mill workers in Kiambu County, Kenya

Abstract

The animal feed industry in Kenya experienced rapid growth, attributed to increased demand for animal feed around major towns in Kenya. This proportionately increased the risk of exposure to grain dust among industrial workers. These risks and health-related impacts have not been adequately studied in Kenya. The goal of the study was to assess the effects of exposure to grain dust on the pulmonary function of selected animal feed mill workers in Kiambu County, Kenya. The study adopted both a cross-sectional and a case-control study design. A total of 355 animal feed mill workers from 35 animal feed firms were included in the study. Assessment of dust management systems was done through structured questionnaires, interviews, and walk-through surveys. The grain dust exposure levels (PM10 and PM2.5) in the study sites were measured using a portable particulate matter sensor model (Temtop, US). A total of 81 animal feed mill workers participated in the assessment of their lung function and respiratory symptoms using the spirometry model. A total of 81 workers from the milk processing companies formed the matched control group. SPSS was used to process and analyse the collected data. The results showed that the majority of the workers had not been trained in grain dust management. The proportion of workers trained on various aspects was as follows: dust management procedures (16.44%), grain dust hazards (3.42%), and usage of PPE (13.70%). None of the workers was aware of the air sampling measurements or the exposure limits. Only 16.13% of the feed mills controlled the dust using engineering and administrative controls, apart from ventilation. The mean PM10 of 53.72±71.32 µg/m3 and PM2.5 of 36.54±41.56 µg/m3 found in this study exceeded the WHO Air Quality Guideline level of a 24-hour exposure time of 45 µg/m3 for PM10 and PM2.5, 15 µg/m3. The mean predicted lung function parameters were FEV1(%)±SD (82.64±21.17), FVC(%) ± SD (88.44±21.76), FEV1/FVC(%)±SD(95.42±20.76), and FEF25-75(%)±SD(80.60±30.69). These were significantly lower for the animal feed mill workers than the control workers for all the parameters (p<.05). Obstructive lung abnormalities were reported among the target group and none in the control group. The most prevalent symptom among the respondents was a stuffy, itchy, and running nose (53.77%), followed by watery and itchy eyes (30.48%), phlegm first thing in the morning during cold periods (13.70%), and cough first thing in the morning during cold periods (12.33%). This study reveals that declining lung function among animal feed mill workers is associated with exposure to grain dust. The study recommends continued implementation of the dust control measures and the introduction of controls, hazard awareness, medical examinations for the workers, and adherence to the set safety and health guidelines by the workers and the firms.