BIOAEROSOL EXPOSURE IN WASTE COLLECTION - A COMPARATIVE-STUDY ON THE SIGNIFICANCE OF COLLECTION EQUIPMENT, TYPE OF WASTE AND SEASONAL-VARIATION

Recent Danish studies on waste collectors' bioaerosol exposure are sum marized. Generally the median exposure levels ranged from 10(5) to 10( 6) cells m(-3) (total microorganisms), 10(4) to 10(5) cfu m(-3) (cultu rable fungi) and 10(3) to 10(4) cfu m(-3) (culturable bacteria). The t ype of waste was a governing factor for exposure. Garden waste collect ors frequently experienced concentrations exceeding 10(5) cfu m(-3) fo r mesophilic fungi and 10(4) cfu m(-3) for the thermophilic fungus Asp ergillus fumigatus. Workers collecting compostable, mixed and sorted w aste occasionally experienced similar concentrations of the fungal gro ups while workers collecting 'bulky waste' and paper had low exposure. Type of collection vehicle was identified as another governing factor for exposure. Vehicles loaded from the top (approximately 3 m above t he ground) caused lower exposure (by a factor of 25) to fungi than veh icles loaded at the level or the breathing zone of the workers. Exposu re was also affected by season of the year-the concentration of total microorganisms, culturable fungi, Aspergillus fumigatus and endotoxin was low in winter. Exposure to total microorganisms counted by microsc opy was found to have a fairly high validity (Va)as an indicator of ex posure to culturable fungi (Va = 1.45) or culturable bacteria (Va = 1. 25). Likewise, dust may also be used as an indicator of exposure to to tal microorganisms (Va = 1.36), culturable fungi (Va = 1.31) and cultu rable bacteria (Va = 1.35). (C) 1997 British Occupational Hygiene Soci ety.