Seasonal variation in bioaerosol exposure during biowaste collection and measurements of leaked percolate

Abstract

The seasonal variation in waste collectors' exposure to microorganisms, endotoxin and dust was measured with personal sampling equipment. The measurement was carried out in three different combinations of storage and collection systems for biowaste: container/compactor truck (C/C), paper sack/compactor truck (P/C) and paper sack/platform truck (P/P). The maximum personal exposure was found to occur during the summer at the following median levels: total microorganisms 9.2 × 10⁵ cells m^-3, culturable fungi (moulds) 7.8 × 10⁴ cfu m^-3, Aspergillus fumigatus 2.9 × 10^-3 cfu m^-3 , mesophilic actinomycetes 9.0 × 10² cfu m^-3, bacteria 1.0 × 10⁴ cfu m^-3, endotoxin 16 EU m ^-3 (1.0 ng m^-3 ) and dust 0.33 mg m^-3. A seasonal variation was observed for microorganisms, moulds, A. fumigatus, mesophilic actinomycetes and endotoxin (P < 0.05). The highest exposure to moulds, A. fumigatus and endotoxin occurred in the C/C system (P < 0.05) during the summer. Percolate from the biowaste was collected from the bottom of the compactor trucks. Concentrations of endotoxin ranged from 3.9 to 8.1 × 10⁵ EU ml^-1 (25 to 52 μg ml ^-1 ) and the microflora of the percolate was dominated by bacteria (1.2 to 2.3 × 10⁹ cfu ml^-1 ). A seasonal variation was observed for concentrations of total microorganisms, moulds and endotoxin with a maximum occurring during the summer (P < 0.05) and no differences were observed between percolate collected from the C/C and the P/C system, respectively. The high volume of percolate generated in biowaste may constitute a potential health hazard to waste collectors on account of the high concentrations of microorganisms and the risk of splashing during collection.