Estimation of herbicide species sensitivity distribution using single‐species algal toxicity data and information on the mode of action

Abstract

Although species sensitivity distribution (SSD) is a key concept for quantitative ecological risk assessment, its application is limited owing to a lack of sufficient data for the analysis, especially on the toxicity of herbicides for primary producers. The authors developed a method of herbicide SSD estimation using single-species toxicity data and information on the herbicide mode of action. The authors' method was based on 2 assumptions: the slopes of the SSD of the same MOA herbicides are the same and the relative sensitivities of standard algae in the SSD of the same MOA herbicides are the same. The 2 parameters of log-normal SSD, mean sensitivity, and variation in sensitivity, for 92 herbicides were determined to establish the estimation model. Mean sensitivities were linearly correlated with logarithmic 50% effect concentrations (EC50) for standard algae. The average of variations in sensitivity significantly differed among MOA, and variations in sensitivity were constant independently of EC50 values for standard algae for the same MOA herbicides. These results were all consistent with the assumptions of the SSD estimation method. The outcome was validated by comparing the estimated SSDs using the proposed method with the generated SSDs using toxicity data which were independent of method development. These SSDs were consistent, and considering MOA information improved the accuracy of estimating SSD markedly.

Ecological effect assessment by species sensitivity distribution for 68 pesticides used in Japanese paddy fields

“…3,35) The results of the present study also clearly showed that the slope of the SSD (ln SD) significantly differed among MoAs. This indicates that the variation in species sensitivity is specific for each MoA.…”

“…A few studies have attempted such estimation using single-species toxicity data and information on the MoA. 3,36) SSD application is limited in many cases owing to a lack of sufficient data. Therefore, the estimation method will be useful for a wide range of SSD applications for ecological effect assessment of various kinds of pesticides.…”

“…Therefore, filling the data gap in an efficient and economical way would be essential to enhance the SSD application. 3,42) Monitoring the actual environmental concentration of pesticides and risk assessment after registration is also important for risk management. Quantification of the ecological risk of pesticides using SSD as the PAF provides a useful tool for risk management.…”

Sensitivity differences among seven algal species to 12 herbicides with various modes of action

“…5) Recently, it was determined that the differences in algal species sensitivity to herbicides are remarkably large. [6][7][8] In our previous study, an efficient and economical high-throughput algal toxicity assay using five riverine periphytic species was developed. 9) The use of a microplate assay, in which periphytic algae are attached to the bottom of a microplate, 10,11) was combined with fluorometric measurement of algal growth with high measurement sensitivity.…”

Studies on ecological risk assessment of pesticide using species sensitivity distribution

“…Therefore, I developed a method of SSD estimation using single-species toxicity data and information regarding the pesticide mode of action. 29) This method was based on two assumptions: (1) the slopes of the SSD of pesticides with the same mode of action are the same, and (2) the relative sensitivities of standard algae in the SSD of pesticides with the same mode of action are the same. The outcome of the SSD estimation method was validated by comparing the estimated SSDs using the proposed method with the generated SSDs, using toxicity data that is independent of the method development.…”