Quantitative Microbial Risk Assessment in Occupational Settings Applied to the Airborne Human Adenovirus Infection

Abstract

Quantitative Microbial Risk Assessment (QMRA) methodology, which has already been applied to drinking water and food safety, may also be applied to risk assessment and management at the workplace. The present study developed a preliminary QMRA model to assess microbial risk that is associated with inhaling bioaerosols that are contaminated with human adenovirus (HAdV). This model has been applied to air contamination data from different occupational settings, including wastewater systems, solid waste landfills, and toilets in healthcare settings and offices, with different exposure times. Virological monitoring showed the presence of HAdVs in all the evaluated settings, thus confirming that HAdV is widespread, but with different average concentrations of the virus. The QMRA results, based on these concentrations, showed that toilets had the highest probability of viral infection, followed by wastewater treatment plants and municipal solid waste landfills. Our QMRA approach in occupational settings is novel, and certain caveats should be considered. Nonetheless, we believe it is worthy of further discussions and investigations.

Keywords: airborne infectious; human adenovirus (HAdV); occupational exposure; quantitative microbial risk assessment.

Figure 1

Concentrations of HAdV in different occupational settings. Sampling sites (average value μ and intervals (μ − σ, μ + σ), σ = standard deviation (SD)). Toilets: (1) four-bed patient room (7.90 GC/m³, SD = 2.81); (2) two-bed patient room (6.86 GC/m³, SD = 3.61); (3) healthcare personnel (6.02 GC/m³, SD = 4.02); (4) office building (4.81 GC/m³, SD = 2.96); wastewater treatment plants: (5) entrance sewage (3.39 GC/m³, SD = 0.73); (6) sludge treatment (2.97 GC/m³, SD = 0.20); (7) biological oxidation tank (3.21 GC/m³, SD = 0.80); (8) side-entrance manhole (2.77 GC/m³, SD = 0.33); solid waste landfill: (9) paper recycling (3.20 GC/m³, SD = 3.46); (10) outside area (2.24 GC/m³, SD = 2.89).

Figure 2

Probability of infection as a function of exposure time in different occupational settings. Sampling sites (average values μ): toilets: (4) office building (4.81 GC/m³); wastewater treatment plants: (5) entrance sewage (3.39 GC/m³); (6) sludge treatment (2.97 GC/m³); (7) biological oxidation tank (3.21 GC/m³); (8) side-entrance manhole (2.77 GC/m³); solid waste landfill: (9) paper recycling (3.20 GC/m³); (10) outside area (2.24 GC/m³).