# Application of the _Aliium_ Test in Toxicity Studies of Lead and Copper: A Cytological Perspective
## 3 Results  
### Analysis of the Effect of Lead on the Mitotic Index  
The ANOVA test results presented in Table 1 highlight the significant influence of dose, time, and their interaction on the mitotic index under lead exposure conditions. The effect of lead on the mitotic index shows a highly significant statistical relevance (\(p<0.001\)), indicating that increasing lead dose results in significant alterations in mitotic activity. \begin{table}
\begin{tabular}{l l l l l l} \hline \hline
**Source** & **Df** & **Sum Sq** & **Mean Sq** & **F Value** & **Pr(\textgreater{}F)** \\ \hline Dose & 4 & 344.3 & 86.09 & 86.41 & \textless{}2 \(\times\)\(10^{-16}\)*** \\ \hline Time & 2 & 48.4 & 24.22 & 24.31 & \(1.85\times\)\(10^{-8}\)*** \\ \hline Dose–Time & 8 & 5.70 & 0.71 & 0.71 & 0.68 \\ \hline Residuals & 60 & 59.8 & 1.00 & & \\ \hline \hline \end{tabular}  
* Significance level: *** \(p<0.001\).  
\end{table} 
Table 1: ANOVA results showing the effects of dose, time, and their interaction on the mitotic index under lead exposure. Another critical factor influencing the reduction in the mitotic index is time, with an equally significant statistical impact (\(p<0.001\)). This underscores that the duration of exposure significantly affects the mitotic index. The interaction between dose and time is not statistically significant (\(p>0.05\)) (Table 1). This indicates that the genotoxic effect of lead at the analyzed doses on the mitotic index does not show an increasing severity based on the duration of exposure. The absence of an interaction between the two factors (dose and exposure time) suggests that this does not occur. This study may reflect the consequence that lead has a cumulative rather than a chronic effect on the cell, with its effects being significant over time. The results of the cytological analyses presented in Table 2 show an inhibitory effect of concentration for different lead concentrations and exposure times, based on the mitotic index and the abnormalities index. The highest mitotic index (MI) values were observed in the control samples (dH\({}_{2}\)O), reaching 11.82% at 24 h, indicating normal mitotic activity. On the other hand, as lead concentration and exposure time increased, varying levels of mitotic index inhibition were observed. At higher lead concentrations, the mitotic index decreased significantly, particularly at 1 mM, for which it reached its lowest level at 72 h (5.06%). This result suggests a progressive inhibitory effect of lead on cell division as concentration or exposure time increase. With regards to the 50% inhibitory concentration relative to the control (IC\({}_{50}\)), the results indicate that this level was reached at concentrations of 0.75 mM and 1 mM after 72 h of exposure. With regards to the abnormal index (AI), no abnormal cells were detected in the control samples. The same result applied to samples treated with 0.25 mM lead. However, the first abnormalities were observed at a concentration of 0.50 mM after 72 h of exposure. This underlines the importance of exposure time in the development of chromosomal abnormalities. Furthermore, the genotoxic effect of lead became more pronounced at higher doses and longer exposure times. As lead concentration and exposure time increased, the abnormality index (AI) rose significantly, reaching 1.81% at 1 mM after 72 h (Table 2). The effect of long-term lead exposure is highlighted by polynomial analyses. The mitotic index (MI) for the control sample remains relatively constant over time, reflecting normal cell division in the absence of lead. Similarly, at a low lead concentration of 0.25 mM, no significant changes were observed, demonstrating that at this concentration, lead does not significantly inhibit cell division during the studied exposure period (Table 2 and Figure 3). On the other hand, at a concentration of 0.50 mM, a reduction in mitotic division capacity becomes evident, indicating the onset of inhibition and a decrease in the mitotic index.