A national study on the residential impact of biological aerosols from the land application of biosolids

Aims: The purpose of this study was to evaluate the community risk of infection from bioaerosols to residents living near biosolids land application sites. Methods and Results: Approximately 350 aerosol samples from 10 sites located throughout the USA were collected via the use of six SKC Biosamplers (R). Downwind aerosol samples from biosolids loading, unloading, land application and background operations were collected from all sites. All samples were analysed for the presence of HPC bacteria, total coliform bacteria, Escherichia coli, Clostridium perfringens, coliphage, enteroviruses, hepatitis A virus and norovirus. Total coliforms, E. coli, C. perfringens and coliphage were not detected with great frequency from any sites, however, biosolids loading operations resulted in the largest concentrations of these aerosolized microbial indicators. Microbial risk analyses were conducted on loading and land application operations and their subsequent residential exposures determined. Conclusions: The greatest annual risks of infection occurred during loading operations, and resulted in a 4 x 10(-4) chance of infection from inhalation of coxsackievirus A21. Land application of biosolids resulted in risks that were < 2 x 10(-4) from inhalation of coxsackievirus A21. Overall bioaerosol exposure from biosolids operations poses little community risk based on this study. Significance and Impact of the Study: This study evaluated the overall incidence of aerosolized micro-organisms from the land application of biosolids and subsequently determined that microbial risks of infection were low for residents close to biosolids application sites.