*2.4. Statistical Analyses*

One-way analysis of variance (ANOVA) tests with a subsequent Games–Howell test evaluated differences in parameter distributions. Levene's tests were used to investigate homoscedasticity (Table S2). Data are presented as means ± standard deviations (SD), and statistical significance was determined at *p* < 0.05. The statistical results are shown in Tables S3–S5.

To assess the effects of the mixed treatment, EC50-72 h values were obtained from each compound, and the mixture treatments were used. Concentration addition (CA) and independent addition (IA) models were used to evaluate the interaction patterns of nickel and BED-47 mixtures, followed by an analysis with the MIXTOX tool [33]. Calculation details were described in a previous study [33]. These models evaluate putative interaction patterns for combinations of chemicals. CA models are generally used to evaluate combinations of chemicals that share the same mechanism of action. In contrast, IA models are generally used for those that exhibit different mechanisms of action. Nevertheless, it is difficult to confirm the model that should be used in many cases. The MIXTOX model can be used with the additional parameter '*a*' to evaluate potential interaction patterns [34,35]. Briefly, the '*a*' parameter was used to evaluate the synergism or antagonism of two chemical interactions, wherein *a* < 0 indicates synergism and *a* > 0 indicates antagonism.
