Association of waste-collection employment with the prevalence of respiratory and irritation symptoms among waste-collection workers

Abstract

Objective: Waste-collecting worker performs various jobs such as collecting, sweeping, and sorting. They are exposed to harmful substances depending on job types, which cause severe respiratory and irritation symptoms. The objective of this study is to investigate a prevalence rate of respiratory and irritation symptoms that waste-collecting workers complained and to examine if types of waste-collecting work influence the development of respiratory and irritation symptoms.Methods: We randomly invited 1,055 waste-collecting workers from 30 private companies and 16 municipal administrative offices. Those waste-collecting workers who collect and handle street and household wastes agreed to participate in this study. The workers who sort municipal and street wastes collected at the plant are also included. The questionnaire first distributed to 1,055 workers was completed by trained interviewers. Our study subjects were involved in the sweeping a street, collecting municipal household waste, and sorting the waste collected for recycling. They were asked to report individual characteristics such as age, gender, duration of employment, wage, average working hours per day, shift work, average working days per week, types of company, and types of waste-collecting work as well as their work. The questionnaire was primarily designed to investigate symptoms pertaining to respiratory (cough, dyspnea, wheeze) and irritation (eye, skin, nose) that they complained. We selected several demographic and work environmental characteristics as independent variables that may be associated with the development of those health symptoms. They were characterized so that the number of categories was appropriately divided for further analysis. Chi-square (2) test was used to examine the difference of demographical and work environmental characteristics, and respiratory and irritation symptoms. Only variables with p-values <0.25 were finally introduced to our multiple logistic regression analysis. Finally, Odd ratios (OR) with 95% confidence intervals (95% CI) of respiratory and irritation symptoms were calculated.Results: The distribution of this study participants (n=1055) was evaluated by demographic and work environmental characteristics. Age (n=993) averaged 48.7 years old (SD: 7.5) with range of 26-68 years old. The average of employment duration (n=1033) was 9.2 years (SD: 6.0) with range of 0.1-28 years. The average of labor wage (n=966) was ₩2,190,800 (SD: ₩456,000) with range of ₩800,000-₩3,300,000. The number of male and female was 986 (93.4%) and 46 (4.3%), respectively. The number of subjects working under 8 hours and over 8 hours during a day were 153 (14.5%) and 696 (66.0%), respectively. 33.4% (352) of study workers were found to use midnight shift, while the number of daytime shift workers were 703 (66.6%). The numbers of subjects working 5 days and over working 5 days per week were 435 (41.2%) and 574 (54.4%), respectively. The number of subjects employed at internal company was 647 (61.3%), and the number of subjects employed at external company was 403 (38.2%). The number of subjects sweeping was 400 (37.9%), the number of subjects collecting was 565 (53.6%), and the number of subjects sorting was 71 (6.7%), respectively.The prevalence rate of Cough, dyspnea, and wheeze was respectively 42.2% (n=445), 19.2% (n=203), and 13.0% (n=137). The prevalence rate of eye, skin, and nose irritation was 49.1% (n=518), 14.3% (n=151), and 28.6% (n=302), respectively.The difference in symptoms among categorical variables was examined by chi-square (2) test. Wage, type of company, average working hours per day, type of waste-collecting work, and average working days per a week were found to be significant factors associating cough symptom (p<0.05). Duration of employment, wage, type of company, the average working hours per a day, and shift work were significantly associated with dyspnea symptom (p<0.05). No environmental and occupational factors was found to be significantly associated with wheeze symptom at p<0.05. Gender and type of waste-collecting work were significantly associated with eye irritation (p<0.05). Duration of employment, wage, type of company, the average work hours per day, type of waste-collecting work, and shift work were significantly associated with skin irritation (p<0.05). Age, Duration of employment, shift work, and the number of work day per a week were significantly associated with nose irritation (p<0.05).We examined the effect of waste-collecting work on the prevalence of respiratory and irritation symptoms among waste-collecting workers using logistic regression analysis. In cough symptom, sweeping (reference) waste-collecting work showed significantly lower risk than that of waste collecting worker (OR: 0.53, 95% CI: 0.36-0.77). Waste-collecting midnight work (reference) was lower risk than daytime waste-collecting work (OR: 0.57, 95% CI: 0.37-0.89). The risk of cough for waste-collecting workers working over 5 days per week (OR: 1.62, 95% CI: 1.18-2.23) was found to be significantly higher than that of worker working less than 5 days (reference). In dyspnea symptom, work environmental and occupational factors were not associated with any characteristics. In wheeze symptom, waste-collecting occupational factors were not associated with the development of wheeze symptom. In eye irritation symptom, the risk for this symptoms by sorting work was 2.18 times (OR: 2.18, 95% CI: 1.16-4.09) higher than that of the Sweeping (reference). In skin irritation symptom, no waste-collecting occupational factors were associated with the development of wheeze symptom. In nose irritation symptom, the development of nose irritation for daytime workers (OR: 0.44, 95% CI: 0.27-0.72) was found to be significantly lower than that of midnight workers (reference). Waste-collecting workers showed almost two times significant higher nose irritation symptoms (OR: 1.90, 95% CI: 1.32-2.72) that that of workers under 5 days (reference).