## 3 Results and Discussion
### Health Risk Assessment of PAHs and Heavy Metals in Settled House Dust
#### 3.5.2 Heavy Metal Risk Exposure in Settled House Dust
As for the parents, the doses were significantly lower with respect to the children, and the differences between the reference doses were larger (2-4 order of magnitude). All HQ values were found to be less than one, and therefore, the risk is limited or even negligible, while as expected all values were found to be higher for children than for adults (Table 6). The element of the house dust associated with the highest noncarcinogenic risk was Cr, for both children and their parents. This finding is in agreement with [PERSON] et al. (2017), who also found that Cr was linked with the highest noncarcinogenic risk. On the scales of dangerousness Cu and Pb followed, while Cd was the element that was linked to the lowest risk, probably because it was detected only in low concentrations. Table 7 presents the lifetime average exposure doses of carcinogenic heavy metals (Cr, Ni, Cd, As) through the inhalation pathway, indicating that the elements are sorted as follows: Cr > Ni > As > Cd. According to the results, the carcinogenic risk exposure dose Exposure Risk was found to be too low to constitute a significant hazard for children and their parents. \begin{table}
\begin{tabular}{c c c} \hline
**Element** & **HQ\({}_{\text{child}}\)** & **HQ\({}_{\text{adult}}\)** \\ \hline Cr & 0.335 & 0.031 \\ Ni & 0.023 & 0.002 \\ Cu & 0.261 & 0.024 \\ Cd & 0.008 & 0.001 \\ Pb & 0.236 & 0.022 \\ Zn & 0.021 & 0.002 \\ Hg & 0.019 & 0.002 \\ As & 0.203 & 0.019 \\ Se & 0.003 & 0.000 \\ \hline \end{tabular}
\end{table} 
Table 6: Noncarcinogenic exposure risk values for children and their parents. \begin{table}
\begin{tabular}{c c c c} \hline
**Element** & **LD\({}_{\text{inh}}\)** & **SF\({}_{\text{inh}}\) (mg-kg\({}^{-1}\)-d\({}^{-1}\))** & **Exposure Risk** \\ \hline Cr & \(9.43\times 10^{-8}\) & 42.00 & \(3.96\times 10^{-6}\) \\ Ni & \(4.32\times 10^{-8}\) & 0.84 & \(3.63\times 10^{-8}\) \\ Cd & \(7.73\times 10^{-10}\) & 6.30 & \(4.87\times 10^{-9}\) \\ As & \(5.71\times 10^{-9}\) & 1.50 & \(8.56\times 10^{-9}\) \\ \hline \end{tabular}
\end{table} 
Table 7: Carcinogenic risk values of trace metal in inhalation exposure pathway. \begin{table}
\begin{tabular}{c c c c} \hline
**Element** & **DD\({}_{\text{total}}\)** & **D\({}_{\text{Ref}}\)** \\ \hline  & **Child** & **Adult** & **Child \& Adult** \\ \hline Cr & \(1.00\times 10^{-3}\) & \(9.33\times 10^{-5}\) & \(3.0\times 10^{-3}\) \\ Ni & \(4.60\times 10^{-4}\) & \(4.27\times 10^{-5}\) & \(2.0\times 10^{-2}\) \\ Cu & \(5.22\times 10^{-3}\) & \(4.85\times 10^{-4}\) & \(2.0\times 10^{-2}\) \\ Cd & \(8.24\times 10^{-6}\) & \(7.66\times 10^{-7}\) & \(1.0\times 10^{-3}\) \\ Pb & \(7.09\times 10^{-4}\) & \(6.59\times 10^{-5}\) & \(3.0\times 10^{-3}\) \\ Zn & \(6.17\times 10^{-3}\) & \(5.73\times 10^{-4}\) & \(3.0\times 10^{-1}\) \\ Hg & \(5.80\times 10^{-6}\) & \(5.39\times 10^{-7}\) & \(3.0\times 10^{-4}\) \\ As & \(6.08\times 10^{-5}\) & \(5.65\times 10^{-6}\) & \(3.0\times 10^{-4}\) \\ Se & \(1.61\times 10^{-5}\) & \(1.50\times 10^{-6}\) & \(5.0\times 10^{-3}\) \\ \hline \end{tabular}
\end{table} 
Table 5: Comparison between the total doses for children and their parents with the reference doses.