# Temporal Variations of Heavy Metal Sources in Agricultural Soils in Malta
## 3 Results and Discussion
### Health Risk Assessment  
HQ values calculated for adults and children (shown in Table 9) are all less than the benchmark value of unity, thus as referenced in literature by [PERSON] and [PERSON] (2010), none of the heavy metals present in the soil for Field A and Field B present quantifiable adverse non-carcinogenic risks [24]. Since the Hazard Index (HI) is also less than unity, these non-carcinogenic adverse effects which may originate through soil ingestion and dermal contact are assumed to be negligible.  
Cancer Risk (CR) values in Table 8 demonstrate that concentrations obtained through analysis pose very low cancer risk in both adults and children. The RI is also very low since the results obtained are below \(10^{-6}\)[22; 26], which suggests that the risk of cancer development is extremely low in any person exposed to the metallic elements reviewed, thus ensuring safety to the landowner and any persons farming the land, together with children who might visit the respective fields.  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Element**} & \multicolumn{2}{c}{**Mean**} & \multirow{2}{*}{**\begin{tabular}{c} \\ **Concentration** \\ \end{tabular} } & \multirow{2}{*}{**\begin{tabular}{c} **HQ\({}_{\text{adults}}\)** \\ \end{tabular} } & \multirow{2}{*}{**\begin{tabular}{c} **CR\({}_{\text{adults}}\)** \\ \end{tabular} } & \multirow{2}{*}{**HQ\({}_{\text{children}}\)**} & \multirow{2}{*}{**\begin{tabular}{c} **CR\({}_{\text{children}}\)** \\ \end{tabular} } & \multirow{2}{*}{**\
\begin{tabular}{c} **Igo** \\ \end{tabular} } & \multirow{2}{*}{**CF**} & \multirow{2}{*}{**
\begin{tabular}{c} **Ei** \\ \end{tabular} } \\  & & & & & & & & \\ \hline Co & 0.100 & N/A \({}^{*}\) & N/A \({}^{*}\) & N/A \({}^{*}\) & N/A \({}^{*}\) & \(-\)0.584 & 1.001 & 5.005 \\ Cr & 0.339 & \(7.951\times 10^{-5}\) & \(9.982\times 10^{-8}\) & \(1.298\times 10^{-7}\) & \(1.858\times 10^{-7}\) & \(-\)5.606 & 0.031 & 0.062 \\ Cu & 0.818 & \(1.216\times 10^{-5}\) & N/A \({}^{*}\) & \(2.248\times 10^{-5}\) & N/A \({}^{*}\) & \(-\)2.875 & 0.204 & 1.022 \\ Fe & 2594.401 & N/A \({}^{*}\) & N/A \({}^{*}\) & N/A \({}^{*}\) & N/A \({}^{*}\) & \(-\)1.136 & 0.683 & N/A \({}^{**}\) \\ Mn & 41.898 & N/A \({}^{*}\) & N/A \({}^{*}\) & N/A \({}^{*}\) & N/A \({}^{*}\) & \(-\)5.299 & 0.038 & 0.038 \\ Ni & 0.461 & \(1.374\times 10^{-5}\) & \(2.475\times 10^{-7}\) & \(2.537\times 10^{-5}\) & \(4.606\times 10^{-7}\) & \(-\)6.023 & 0.023 & 0.115 \\ Pb & 3.034 & \(5.225\times 10^{-4}\) & \(1.520\times 10^{-8}\) & \(9.563\times 10^{-4}\) & \(2.829\times 10^{-8}\) & \(-\)2.154 & 0.337 & 1.686 \\ Sr & 9.969 & N/A \({}^{*}\) & N/A \({}^{*}\) & N/A \({}^{*}\) & N/A \({}^{*}\) & \(-\)6.520 & 0.016 & N/A \({}^{**}\) \\ Zn & 207.262 & \(4.137\times 10^{-4}\) & N/A \({}^{*}\) & \(7.608\times 10^{-4}\) & N/A \({}^{*}\) & 2.788 & 10.363 & 10.363 \\ H\({}_{\text{adults}}\) & & & & & \(1.042\times 10^{-3}\) & & & & \\ HI\({}_{\text{children}}\) & & & & & \(1.895\times 10^{-3}\) & & & & \\ R\({}_{\text{dudus}}\) & & & & & \(3.625\times 10^{-7}\) & & & & \\ R\({}_{\text{children}}\) & & & & & \(6.746\times 10^{-7}\) & & & & \\ PERI & & & & & 18.291 & & & & \\ \hline \hline \end{tabular}  
\({}^{**}\) Toxic response factor values for the respective elements were not documented in other researched studies.  
\end{table}
Table 9: Results for the Health Risk Assessment and the Potential Ecological Risk Assessment variables \({}^{3}\).  
This health risk assessment study matches the outcome of concentration results for the heavy metals studied. None of the elements was higher than limit values set, and although Zn content was higher than documented in other studies, its content was still within the acceptable range; thus, its level of contamination was minimal.