Eun Chae Yim

Comparison of the acute toxicities of novel algicides, thiazolidinedione derivatives TD49 and TD53, to various marine organisms

Acute toxicity assessments of new algicides, thiazolidinedione derivatives TD49 and TD53, to the marine ecological system were conducted. The toxicity assessments were performed using two of the new International Organization for Standardization (ISO) standard methods employing Ulva pertusa Kjellman and three species representative of the marine ecological system, with the results compared by calculating the 50% effective concentration (EC50), 50% lethal concentration (LC50), no-observed-effect concentration (NOEC), and predicted-no-effect concentration (PNEC). In the acute toxicity assessment using the Kjellman, the EC50, NOEC, and PNEC of TD53 were 1.65 µM, 0.08 µM, and 1.65 nM, and those of TD49 were 0.18 µM, 0.63 µM, and 0.18 nM. In the assessments using Skeletonema costatum, Daphnia magna, and Paralichthys olivaceus fry, the EC50 or LC50 of TD53 were 1.53, 0.61, and 2.14 µM, respectively, indicating that D. magna was the most sensitive. The calculated NOEC and PNEC to D. magna were 0.25 µM and 6.10 nM, respectively. The LC50s (or EC50) of TD49 for the three species were 0.34, 0.68, and 0.58 µM. The NOEC and PNEC to S. costatum, the most sensitive species, were 0.2 µM and 3.4 nM, respectively. The slight difference in the chemical structures of the algicides caused significantly different sensitivities and specificities in the toxicities to the employed species. The results of the toxicity assessments showed that application concentrations for algiciding of red tide blooms were higher than the corresponding PNEC values. Therefore, we suggest that a formulization study of the algicides with high specificity should be conducted to reduce the surrounding ecological toxicity.

Acute toxicity assessment of Osthol content in bio-pesticides using two aquatic organisms

Objectives This study focused on the assessment of acute toxicity caused by Osthol, a major component of environment-friendly biological pesticides, by using two aquatic organisms. Methods The assessment of acute toxicity caused by Osthol was conducted in Daphnia magna and by examining the morphological abnormalities in Danio rerio embryos. Results The median effective concentration value of Osthol in D. magna 48 hours after inoculation was 19.3 μM. The median lethal concentration of D. rerio embryo at 96 hours was 30.6 μM. No observed effect concentration and predicted no effect concentration values of Osthol in D. magna and D. rerio were calculated as 5.4 and 0.19 μM, respectively. There was an increase in the morphological abnormalities in D. rerio embryo due to Osthol over time. Coagulation, delayed hatching, yolk sac edema, pericardial edema, and pigmentation were observed in embryos at 24–48 hours. Symptoms of scoliosis and head edema occurred after 72 hours. In addition, bent tails, ocular defects, and symptoms of collapse were observed in fertilized embryo tissue within 96 hours. Ocular defects and pigmentation were the additional symptoms observed in this study. Conclusions Because Osthol showed considerable toxicity levels continuous toxicity evaluation in agro-ecosystems is necessary when bio-pesticides containing Osthol are used.