Lung function status of some Nigerian men and women chronically exposed to fish drying using burning firewood

OBJECTIVE: To determine the lung function status of some Nigerian men and women chronically exposed to fish drying using burning firewood. DESIGN: Case control study. SETTING: Ibaka, Utaewa and Ikanga fishing settlements. SUBJECTS: 183 males and 192 females engaged in fishing, aged 20 to 45 years who have been exposed for a minimum of five years as cases. The control group comprised sex matched male (142) and female (152) Nigerians from the same area who were not exposed to any known air pollutant. MAIN OUTCOME MEASURES: Lung function indices: FVC, FEV1, FEV1% and PEFR. RESULTS: Lung function indices were significantly lower in men engaged in fishing than in their controls: FVC [mean (SD): 2.98 (0.20) vs 3.52 (0.29), p < 0.001]; FEV1 [2.08 (0.18) vs 2.82 (0.25), p < 0.001]; FEV1% [69.8 (3.1) vs 80.2 (6.7), p < 0.001]; and PEFR [335 (22) vs 592 (99), p < 0.001], respectively. Similarly, lung function indices were lower in females in the fishing industry than in their controls; FVC [2.42 (0.17) vs 3.02 (0.24), p < 0.001]; FEV1 [1.70 (0.19) vs 2.55 (0.21), p < 0.001]; FEV1% [72.9 (3.2) vs 84.4 (6.7), p < 0.001]; and PEFR [298 (22) vs 418 (34), p < 0.001]. All the lung function indices (except FEV1%) of the fishermen and women declined significantly (p < 0.001) with their duration of exposure. The results showed a predominantly mixed pattern (restrictive and obstructive) of respiratory defect. There were higher prevalences of respiratory and other symptoms among the cases than the controls. The respiratory symptoms included cough with sputum, chest pain, dyspnoea catarrh and sneezing and unproductive cough. Other symptoms were eye and skin irritation, internal heat and headache. CONCLUSIONS: Chronic exposure to fish drying using burning firewood can impair lung function and cause respiratory and other symptoms.