## 4 Discussion  
Toxic metals, to a large extent, are dispersed in the environment through industrial effluents, organic wastes, refuse burning and transport and power generation. They can be carried to locations many miles away from their sources by wind, depending upon whether they are in gaseous or particulate form. Metallic pollutants are ultimately washed out of the air onto land or the surfaces of waterways. Thus, air is also a route for the pollution of environment. Metals containing industrial effluents constitute major sources of metallic pollution of the hydrosphere [22]. Heavy metal is a broad term used to describe a group of naturally occurring metallic elements of high molecular weight and density when compared to water. At low concentrations, certain heavy metals, such as iron (Fe), zinc (Zn), copper (Cu) and manganese (Mn), are essential for human survival, but they can become toxic agents at higher concentrations. Other heavy metals, such as arsenic (As), cadmium (Cd), lead (Pb), thallium (TI) and mercury (Hg), serve no biological purpose. However, they inevitably enter the human body due to their presence in the environment. Similarly to the essential metals, they induce toxicity once certain concentrations are reached [23]. Specifically, heavy metals induce oxidative stress by generating free radicals and reducing antioxidant levels. Heavy metals also alter the confirmation of protein and DNA and inhibit their function. Chelation therapy is commonly used to treat metal toxicity. Chelation is a chemical process that occurs when the interaction between a central metal atom/ion and a ligand leads to the formation of a complex ring-like structure. The ligand has a donor ion/molecule, which has a lone pair of electrons and may be monodentate to polydentate. Since each metal has a different reactivity with a ligand, a specific chelation agent is required for each metal. Combination therapy with a chelating agent and an antioxidant led to improved outcomes [24]. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Groups** & **Fe Group** & **Zn Group** & \begin{tabular}{c} **Fe-Juglone** \\ **Group** \\ \end{tabular} & \begin{tabular}{c} **Zn-Juglone** \\ **Group** \\ \end{tabular} & \begin{tabular}{c} **Zn-Juglone** \\ **Group** \\ \end{tabular} & \
\begin{tabular}{c} **Control Group** \\ \end{tabular} \\ \hline
\begin{tabular}{c} apoptotic cell \\ count \\ \end{tabular} & \(51.66\pm 2.91\) * & \(50.60\pm 2.40\) * & \(14.00\pm 3.80\) * & \(13.60\pm 3.049\) * & \(12.60\pm 1.81\) */ * \\ \hline \hline \end{tabular}  
* There is a significant difference between the Fe group and the control and Fe-juglone group, \(p=0.001\). ** There is a significant difference between the Zn group and the control and Zn-juglone groups, \(p=0.001\).  
\end{table} 
Table 2: Mean number of apoptotic cells in groups of liver tissue. Figure 3: (**a**) Fe group, apoptotic cells in liver, TUNEL, \(\times 40\); (**b**) Zn group, apoptotic cells in liver, TUNEL, \(\times 40\); (**c**) control group, apoptotic cells in liver, TUNEL, \(\times 40\). Aluminum-oxide nanoparticles (Al\({}_{2}\)O\({}_{3}\)NPs) and zinc -oxide nanoparticles (ZnONPs) are involved in many industries and they are extensively abundant in many aspects of human life [25]. Zinc is a very common pollutant in the environment; its occurrence may influence water-based ecological environments. Consequently, many studies have been directed toward the spread of zinc in water environments. Anthropogenic activities, including municipal wastewater release and coal-burning power plants, industrial methods involving metals and atmospheric outcomes are the main sources of zinc contamination. The extreme discharge of zinc contaminated the surface water and subsurface environment and contributed to groundwater pollution [26]. Organ damage arising from chronic iron overload is remarkable for the range of tissues affected (both replicative and nonreplicative) and for the often slow and insidious onset of organ dysfunction.