Exposure to wood dust and endotoxin in small-scale wood industries in Tanzania

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Abstract
Workers in small-scale wood industries (SSWI) have increased risks of developing asthma and other respiratory diseases. Wood dust and microbial agents have both been suggested to play a role, but few studies have measured endotoxin exposure in SSWI in Africa. We assessed inhalable dust levels in 281 samples from 115 workers and bacterial endotoxins levels in 157 samples from 136 workers from SSWI in Dar es Salaam, Tanzania. The overall geometric mean of personal exposure was 3.3 mg/m3; geometric standard deviation (GSD) 2.5; range 0.45–67.0 mg/m3) and 91 EU/m3 (GSD 3.7; range 9–4914.8 EU/m3) for wood dust and endotoxins, respectively. Dust and endotoxin levels were weakly correlated (r=0.44, n=157, P<0.0001). Between- and within-worker variances and percentages explained by the differences among job titles and seasons were 0.31 (9%) and 0.35 (30%), respectively, for wood dust exposure, and 0.35 (0%) and 0.35 (38%) for endotoxin exposure. Higher dust and endotoxin exposure levels were observed in the dry compared to the wet season, after correcting for differences in exposure between jobs. Carving and manual cleaning were associated with the highest dust exposures. Sewing seat covers and manual cleaning were associated with the highest endotoxin exposures. Dust and endotoxin exposure levels in SSWI are high and appropriate control measures are necessary.