## 4 Conclusions  
This study gives a comprehensive assessment of the metal contamination and the associated environmental health risk of the following metals: Cu, Zn, Pb, Fe, and Cr in the sediments of the water bodies surrounding the area of the former ferrochromium plant. The metal concentrations in the sediments could be attributed to the former plant's activity. The Cr level at all sites exceeded the permissible limit. The highest values were reached for Cr and Fe at site 2 (S2, \"Huta\"), which is located closest to the slag heap. The concentrations of the metals were relatively lower at the other sampling sites where the distance from the heap was greater. The toxicity towards living organisms was tested via the application of commercial tests: Ostracodtotoxit F for assessing the toxicity of the sediments and Daphtoxkit F magna and Algaltoxkit F for the water toxicity studies. In the case of sediments, a 30% death rate for _H. incongruenus_ was recorded in the sediments at the \begin{table}
\begin{tabular}{c c c c} \hline \multirow{2}{*}{**Site**} & **Toxic Metals** & \multicolumn{2}{c}{**ECR**} \\ \cline{2-4}  & **[mg/kg]** & **Children** & **Adults** \\ \hline \multirow{3}{*}{S1} & Cr & \(7\times 10^{-1}\) & \(2.6\times 10^{-1}\) \\ \cline{2-4}  & Pb & \(3.6\times 10^{-4}\) & \(1.36\times 10^{-4}\) \\ \hline \multirow{3}{*}{S2} & Cr & \(2.23\times 10^{0}\) & \(8.3\times 10^{-1}\) \\ \cline{2-4}  & Pb & \(9.3\times 10^{-4}\) & \(3.5\times 10^{-4}\) \\ \hline \multirow{3}{*}{S3} & Cr & \(1\times 10^{-1}\) & \(4\times 10^{-2}\) \\ \cline{2-4}  & Pb & \(2.8\times 10^{-4}\) & \(1.03\times 10^{-4}\) \\ \hline \end{tabular}
\end{table} 
Table 11: ECR values for children and adults for the sediments at all the studied sites: S1 \"Blekitna\", S2 \"Huta\", and S3 \"Mala Szwecja\" [mg/kg]. closest site to the landfill (S2, \"Huta\"). The highest mortality of _D. magna_ (40% after 48 h) was observed in the water taken at this site (S2, \"Huta\"), and for algae, the lowest values of LC50 were calculated at S2 also, proving that the water in this reservoir still poses a health risk to living organisms, which also corresponds to the highest concentrations of studied elements recorded at this site. The results calculated from the sediments generally showed that the former ferrochromium plant poses the highest risk. The health exposure expressed by the health risk hazard quotient decreases as follows: HQing > HQderm > HQinh. The HI value for Cr for children was above 1, which indicates the high health impact of this metal when ingested by children. ECR was determined for Cr and Pb. All the values were above the range limit of \(10^{-6}\). The ECR value for Cr was the highest in the sediments at the site closest to the landfill for both children and adults. Therefore, the cancer risk from Cr and Pb for both children and adults was found to be very high. Pb and Cr were determined to have extremely high environmental risks due to their high concentrations. Thus, the former ferrochromium plant can be harmful to health when considering Cr and Pb contamination, and it is possible that potential danger to humans consuming fish from this water reservoir, as well as to other living organisms, currently exists in the water reservoir. In other studied water bodies, even though the risk is lower, it still exists. In conclusion, because of the potential risk of toxic metal contamination, efforts to control this area should be made, especially when considering the proven Cr contamination. Therefore, further research is needed in this area, particularly focusing on the bioaccumulation of metals in fish and assessing the change in metal content in the bottom sediments as a function of depth, which will give precise information about the potential health risk. This comprehensive risk assessment is essential for the risk assessment of the sediments from these studied water reservoirs.