## 3 Results
### 24 h Binary Mixture of Cd + Zn--MixTOX Analysis  
In the 24 h dataset for Cd + Zn exposure in _E. aeidiculatus_, the concentration addition (CA) module is statistically significant, although it explains a relatively small proportion of the data variance. The inclusion of different sub-models improves the explanation of the data variance up to 77%. However, these models generally struggle to accurately predict mixture toxicity (Table 2). Specifically, the S/A model and the DR models both yield positive values for their parameters (\(a\) and \(b\)), which typically indicate antagonism in CA systems. However, the DR model shows synergism at low doses and antagonism at high doses. Notably, a strong synergistic effect was observed at the lowest concentrations of chemical 1 (Cd) and chemical 2 (Zn) (0.25 TU), followed by antagonism in the central dose range and again synergism at the highest tested concentrations tested. This non-linear dynamic could be attributed to hormesis, as observed in previous studies [54; 55; 56].  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**HMs**} & \multicolumn{2}{c}{**1 h—_Eupletes_} & \multicolumn{2}{c}{**24 h—_Eupletes_} \\ \cline{2-5}  & **LC\({}_{\text{20}}\)** (mg L\({}^{-1}\))** & **LC\({}_{\text{20}}\)** (mg L\({}^{-1}\))** & **LC\({}_{\text{20}}\)** (mg L\({}^{-1}\))** & **LC\({}_{\text{20}}\)** (mg L\({}^{-1}\))** \\ \hline CdCl\({}_{3}\) & 42.53 & 91.80 & 19.85 & 53.72 \\ CuS\({}_{\text{04}}\) & 34.78 & 76.41 & 0.18 & 0.43 \\ ZnS\({}_{\text{04}}\) & 282.41 & 283.95 & 76.47 & 137.65 \\ \hline \hline \multicolumn{5}{c}{**1 h—_Eupletes_} & \multicolumn{2}{c}{**24 h—_Eupletes_} \\ \cline{2-5}  & **LC\({}_{\text{20}}\)** (mg L\({}^{-1}\))** & **LC\({}_{\text{20}}\)** (mg L\({}^{-1}\))** & **LC\({}_{\text{20}}\)** (mg L\({}^{-1}\))** & **LC\({}_{\text{20}}\)** (mg L\({}^{-1}\))** \\ \hline CuO & 5922.50 & 6535.03 & 3.10 & 4.93 \\ ZnO & 77.32 & 139.99 & 30.93 & 56.16 \\ TiO\({}_{2}\) & 702.94 & 7361.62 & 2608.55 & 4439.97 \\ \cline{2-5} SiO\({}_{2}\) & \multicolumn{4}{c}{Up to 60,080 mg L\({}^{-1}\), there is no effects to the cells} \\ \cline{2-5}  & & & & \\ \hline \hline \end{tabular}
\end{table}
Table 1: LC\({}_{\text{20}}\) and LC\({}_{\text{50}}\) values of _E.aeidiculatus_ for HMs and NPs at 1 h and 24 h.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**CdCl\({}_{\text{2}}\) + ZnS\({}_{\text{04}}\)Exposure**} & \multirow{2}{*}{**Parameter**} & \multicolumn{4}{c}{**The Concentration Addition (CA)-Based Module**} \\  & & **CA** & **S/A** & **DR** & **DL** \\ \hline
1 h & \(a\) & – & 1.405 & 0.917 & 0.106 \\  & \(b\) & – & – & 1.018 & \(-\)7.852 \\  & \(R^{2}\) & 0.34 & 0.85 & 0.85 & 0.87 \\  & \(p(\chi 2)\) CA vs. & – & \(1.8\times 10^{-232}\) \(*\) & \(2.3\times 10^{-232}\) \(*\) & \(2.98\times 10^{-238}\) \(*\) \\  & S/A vs. & – & – & 0.008 \(*\) & \(5.247\times 10^{-09}\) \(*\) \\
24 h & \(a\) & – & 1.54 & 0.724 & \(-\)0.362 \\  & \(b\) & – & – & 0.414 & 2.088 \\  & \(R^{2}\) & 0.72 & 0.77 & 0.77 & 0.77 \\  & \(p(\chi 2)\) CA vs. & – & \(7.04\times 10^{-21}\)\(*\) & \(4.86\times 10^{-08}\)\(*\) & \(3.61\times 10^{-18}\)\(*\) \\  & S/A vs. & – & – & \(0.486\times 10^{-08}\)\(*\) & \(3.206\times 10^{-05}\)\(*\) \\ \hline \hline \end{tabular}
\end{table}
Table 2: Fitting results of the toxicity data of the bimetallic mixture (Cd + Zn) to the four models describing the deviations from concentration addition (CA) and independent action (IA) of _Eupletes aeidiculatus_ using the MixTOX tool.