## 2 Materials and Methods
### Pollution Indices of Soil Contamination and Potential Human Health Risk Assessment
Cancer risk (CR), that is, a unitless probability of an individual developing cancer over time, was determined for elements As, Ni and Cd by using Equation (16) from Table 1, with the factors explained in Table 2.  
With respect to HQ, the hazard index (HI) was determined for 6 heavy metals (Cu, As, Ni, Zn, Cd and Hg) by using the equation presented in Table 1 and the explained parameters presented in Tables 2 and 3. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Parameter** & **Definition** & **Unit** & **Value for Children** & **References** \\ \hline \multirow{3}{*}{IngR} & Soil ingestion rate & [mg day\({}^{-1}\)] & 200 & [12; 47; 48; 49] \\  & depending on age & & & \\  & Exposure frequency & [days year\({}^{-1}\)] & 350 days & [47; 48; 49] \\  & Exposure duration & [year] & 6 & [12; 47; 48; 49] \\  & Average body weight & [kg] & 15 & [12; 47; 48; 49] \\  & Average time & [days] & ED \(\times\) 365 & [48; 49] \\  & InhR & Inhalation rate & [m\({}^{3}\)/day] & 7.6 & [12; 48; 49] \\  & PEF & Particle emission factor & [m\({}^{3}\) kg\({}^{-1}\)] & 1.36 \(\times\) 10\({}^{9}\) & [12; 42; 48; 49] \\  & Skin area exposed to & & & \\  & pollutant & & & \\  & Skin adherence factor & [mg cm\({}^{-2}\) day\({}^{-1}\)] & 0.2 & [12; 42; 48; 49] \\  & Thermal absorption & none & 0.001 (for all the metals) & [12; 48] \\  & factor & & & \\  & Volatilization factor & [mg\({}^{3}\) kg\({}^{-1}\)] & 32,675.6 & [12; 48] \\  & Average chemical daily & & & \\  & intakes of humans via & [mg kg\({}^{-1}\) day\({}^{-1}\)] & – & [18] \\  & all three pathways & & & \\  & Risk reference slope & & & \\  & factor & & & \\  & Inhalation unit risk & [(ug/m\({}^{3}\))\({}^{-1}\)] & & [41] \\  & Concentration of & & & \\  & element & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The definition and unit of measurement for the used parameters. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Element** & \multicolumn{4}{c}{**RfD [mg kg\({}^{-1}\) day\({}^{-1}\)] for Various Pathways**} & \multirow{2}{*}{**SF\({}_{ing}\)**} & \multirow{2}{*}{**IUR**} \\ \cline{2-2} \cline{5-6}  & **Ingestion** & **Dermal** & **Inhalation** & **Inhalation of Hg Vapor** & \\ \hline Cu & \(4\times 10^{-2\,\text{(a)}}\) & \(4\times 10^{-2\,\text{(a)}}\) & \(1.2\times 10^{-2\,\text{(a)}}\) & – & – \\ As & \(3\times 10^{-4\,\text{(a)}}\) & \(3.01\times 10^{-4\,\text{(a)}}\) & \(1.23\times 10^{-4\,\text{(a)}}\) & – & \(1.5\,\text{(c)}\) & \(4.3\times 10^{-3\,\text{(c)}}\) \\ Ni & \(2\times 10^{-2\,\text{(a)}}\) & \(2.06\times 10^{-2\,\text{(a)}}\) & \(5.4\times 10^{-3\,\text{(a)}}\) & – & – & \(2.6\times 10^{-4\,\text{(c)}}\) \\ Zn & \(3\times 10^{-1\,\text{(a)}}\) & \(3\times 10^{-1\,\text{(a)}}\) & \(6\times 10^{-2\,\text{(a)}}\) & – & – & \\ Cd & \(1\times 10^{-3\,\text{(a)}}\) & \(1\times 10^{-3\,\text{(a)}}\) & \(5\times 10^{-5\,\text{(a)}}\) & – & – & \(1.8\times 10^{-3\,\text{(c)}}\) \\ Hg & \(3\times 10^{-4\,\text{(a)}}\) & \(8.57\times 10^{-5\,\text{(a)}}\) & \(2.1\times 10^{-5\,\text{(a)}}\) & \(8.75\times 10^{-5\,\text{(b)}}\) & – & – \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Toxicants’ risk reference doses (RfDs), risk reference slope factor (SF) and inhalation unit risk (IUR). In the case of the hazard index, the permitted value is 1; if this value is exceeded, the corresponding metal might be harmful for human health.