"This study developed dose response models for determining the probability of eye, respiratory or central nervous system infections from previously conducted studies using Naegleria fowleri, Acanthamoeba spp. and Pseudomonas aeruginosa. These opportunistic pathogens have been identified in drinking water and premise plumbing systems, and a lack of dose response models for the appropriate exposure routes of concern has prevented researchers from quantifying the risk they pose to human health. Using the newly developed dose response model for P. aeruginosa, a reverse quantitative microbial risk assessment (QMRA) was completed to determine the threshold concentrations of P. aeruginosa associated with an annual risk of 10-4 for corneal and inhalation exposures. The results indicated that an average concentration of 1 CFU/L in the bulk water could result in an annual risk greater than the guideline set by the Environmental Protection Agency. The threshold concentration responsible for a 10 -4 risk of pneumonia from P. aeruginosa was 11 orders of magnitude greater than the threshold concentration for bacterial keratitis. Modeling all possible exposure routes of concern for opportunistic pathogens in drinking water is critical, as the exposure route dramatically affects the concentrations of concern. This reverse QMRA and future risk assessments that utilize the dose response models developed in this study can be used to inform decisions on drinking water treatment, monitoring protocols, and future plumbing design."--Page ii.
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