## 2 Materials and Methods
### Exposure Assessment  
The focus of this exposure assessment was the estimation of the likelihood of exposure by an individual to the identified hazard. The key elements and variables included were the concentrations and survival of key pathogens, specifically _Salmonella_ bacteria, adenoviruses, _Cryptosporidium_ and _Giardia_ spp., on raw vegetable crops watered by drip, spray or subsurface drip irrigation over a period of 30 days. To more fully evaluate the exposure of individuals to the ingestion of contaminated foods, the survival (and decay) of those pathogens on food products was considered. Natural processes, such as temperature, dissolved solids, UV/sunlight radiation exposure, relative humidity and moisture content (water activity), may impact the survival of pathogens on food products. As a component of this model, a decay constant was incorporated into the pathogen concentration term (C\({}_{\rm C}\)). The decay constants (\(k\)) used for this analysis for each class of microorganism are listed in Table 1. Microbial concentrations were calculated using the following equation:  
\[{\rm C_{c}=C_{RW}\left[exp(-kt_{d})\right]} \tag{1}\]  
where C\({}_{\rm c}\) is the concentration of pathogens in organisms/L at elapsed time t\({}_{\rm d}\) after irrigation or at consumption, C\({}_{\rm RW}\) (organisms/L) is the initial pathogen concentration in reclaimed water samples, \(k\) is the kinetic decay constant (d\({}^{-1}\)), and t\({}_{\rm d}\) is the elapsed time between final irrigation and consumption in days. The exposure to the ingestion of contaminated food can be estimated as the product of the pathogen concentration in the consumed food and the amount of food consumed per day [21], as represented in the equation developed by [PERSON] et al., 2006 [7], below:  
\[{\rm D_{i}=f_{raw}M_{body}M_{i}C_{c}V_{eq}exp(-kt_{d})} \tag{2}\] \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Model Parameter and** & **Symbol** & **Unit** & **Distribution and Fit Parameter** & **Reference** \\ \hline Organism Concentration in & & & & Calculated from \\ NCT2 RW & & & Normal, fitted to log data & 22 reclaimed water \\ \hline Adenovirus A–F & & & & \\ \hline _Salmonella_ spp. & & & & \\ \hline _Cryptosporidium_ spp. & & & Normal \(\mu\): 0.13,\(\sigma\): 0.45) & \\ \hline _Giardia_ spp. & & & Normal \(\mu\): 0.22,\(\sigma\): 0.36) & \\ \hline Daily fruit and vegetable & & & & \\ consumption & & & & \\ \hline Percentage of fruit and & & & & \\ vegetables consumed raw & \(f_{raw}\) & - & Triangular (0.25, 0.5, 0.75) & [PERSON] and Oron, 2010 [18] \\ \hline Kinetic decay constant & & & & \\ \hline Viruses & & & & \\ \hline Bacteria & & & & PE, 0.69 & [PERSON] et al., 1992 [19] \\ \hline Protozoan parasites & & & & PE, 0.147 & \\ \hline Body mass & \({\rm M_{body}}\) & kg & & \\ \hline Equivalent volume & & & & \\ \hline Spray irrigation & & & & \\ \hline \multirow{2}{*}{Drip irrigation} & & & & PE, 1.6 \(\times\) 10\({}^{-4}\) & \\ \cline{3-4}  & & & & Triangular (1.6 \(\times\) 10\({}^{-7}\), 1.6 \(\times\) 10\({}^{-6}\), & Van Ginneken and Oron, 1.6\(\times\) 10\({}^{-5}\)) & 2010 [18] \\ \hline Subsurface drip irrigation & & & & Triangular (1.6 \(\times\) 10\({}^{-8}\), 1.6 \(\times\) 10\({}^{-7}\), & \\ \cline{3-4}  & & & & 1.6\(\times\) 10\({}^{-6}\)) & \\ \hline Period between irrigation & & & & \\ and consumption & t\({}_{\rm d}\) & Days & 0, 15, 30 & - \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Summary of distributions and fit parameters used in models.