Exposure to dust, endotoxin and micro-organisms in the potato processing industry

Abstract

Exposure to organic dust components was studied in four potato processing plants because preliminary results showed high exposures accompanied by work-related health complaints. Ambient air concentrations of inhalable dust ranged from below 0.4 up to 44 mg m−3 [geometric mean (GM) 0.64 mg m−3]. Respirable dust concentrations were considerably lower. Personal concentrations of inhalable dust were somewhat higher, and strongly related to a few working tasks dealing with dried starch or protein. Ambient air concentrations of endotoxin ranged from 0.5 to more than 60 000 endotoxin units (EU) per m3 for the inhalable size fraction (GM = 280 EU m−3). For the respirable size fraction, endotoxin concentrations were lower (about the same factor as for dust). Personal endotoxin concentrations were lower than ambient air concentrations, probably because workers did not work the whole period of the shift near endotoxin sources. Endotoxin exposure was evaluated as very high; 23% of the workers had a mean exposure above 1000 EU m−3 (100 ng m−3). Differences between plants had a large influence on both dust and endotoxin exposure. A fairly good correlation was found between counts of airborne gram-negative bacteria and airborne endotoxin of the respirable size fraction. Ambient air levels of bacteria and endotoxin were strongly related to process water temperature, suggesting that exposure reduction can be achieved by lowering this temperature or by other measures that inhibit bacterial growth. We conclude that recycling of process water probably constitutes an exposure source of bacteria and endotoxin in many facilities.