Toxicity interactions of azole fungicide mixtures on Chlorella pyrenoidosa

Abstract

It is acknowledged that azole fungicides may release into the environment and pose potential toxic risks. The combined toxicity interactions of azole fungicide mixtures, however, are still not fully understood. The combined toxicities and its toxic interactions of 225 binary mixtures and 126 multi‐component mixtures on Chlorella pyrenoidosa were performed in this study. The results demonstrated that the negative logarithm 50% effect concentration (pEC50) of 10 azole fungicides to Chlorella pyrenoidosa at 96 h ranged from 4.23 (triadimefon) to 7.22 (ketoconazole), while the pEC50 values of the 351 mixtures ranged from 3.91 to 7.44. The high toxicities were found for the mixtures containing epoxiconazole. According to the results of the model deviation ratio (MDR) calculated from the concentration addition (MDRCA), 243 out of 351 (69.23%) mixtures presented additive effect at the 10% effect, while the 23.08% and 7.69% of mixtures presented synergistic and antagonistic effects, respectively. At the 30% effect, 47.29%, 29.34%, and 23.36% of mixtures presented additive effects, synergism, and antagonism, respectively. At the 50% effect, 44.16%, 34.76%, and 21.08% of mixtures presented additive effects, synergism, and antagonism, respectively. Thus, the toxicity interactions at low concentration (10% effect) were dominated by additive effect (69.23%), whereas 55.84% of mixtures induced synergism and antagonism at high concentration (50% effect). Climbazole and imazalil were the most frequency of components presented in the additive mixtures. Epoxiconazole was the key component induced the synergistic effects, while clotrimazole was the key component in the antagonistic mixtures.

Mechanism of the Synergistic Toxicity of Ampicillin and Cefazoline on Selenastrum capricornutum

“…To maintain the algal culture, a BG11 medium was utilized, and the culture was incubated in a constant light environment at 22 °C with an illuminance ranging from 2000 to 3000 Lux. The light–dark cycle was set at 12 h of light followed by 12 h of darkness [ 36 , 42 ]. Algal specimens in the logarithmic growth phase were selected for experimentation.…”

“…The AMP (3.47 × 10 −7 mol/L–6.59 × 10 −5 mol/L, dilution factor = 0.4) and CZO (1.37 × 10 −6 mol/L-2.73 × 10 −4 mol/L, dilution factor = 0.4) concentration ranges are based on the mixture test concentration and the mixing ratio. Following a 96 h exposure period, the growth inhibition ratio ( I ) was calculated for S. capricornutum in response to the two individual pollutants as well as their combination, utilizing the following formula [ 36 , 43 , 44 , 45 , 46 ]: where OD t0 and OD ti are the optical density (OD) of the treatment at 0 and 96 h, respectively. OD 00 and OD 0i are the OD of the controls at 0 and 96 h, respectively.…”

“…In the analysis of the concentration inhibition data, we applied the classical two-parameter nonlinear functions, specifically the Weibull function (Equation (2)) and the Hill function (Equation (3)). These mathematical models have been widely utilized in the field [ 6 , 36 , 44 , 47 , 48 ]. The selection of the optimal fitting function was based on either achieving the maximum determination coefficient ( R 2 ) or the minimum root-mean-square error ( RMSE ) [ 36 ].…”

“…These mathematical models have been widely utilized in the field [ 6 , 36 , 44 , 47 , 48 ]. The selection of the optimal fitting function was based on either achieving the maximum determination coefficient ( R 2 ) or the minimum root-mean-square error ( RMSE ) [ 36 ]. where α and β are the position and slope parameters in Equation (2), respectively; α and β represent the maximum effect and EC 50 in Equation (3), respectively; E is the effect; and x is the concentration of an individual compound or mixture.…”

“…Although the toxicity of AMP and CZO when exposed to algae alone has been tested, no combined toxicity of the two has been reported [ 9 ]. In natural aquatic ecosystems, multiple classes of antibiotics are often detected concurrently [ 35 , 36 , 37 ]. Consequently, aquatic organisms may face exposure to antibiotic mixtures, where synergistic or antagonistic interactions may occur between antibiotics [ 38 ].…”