Effects of bisphenol A on the freshwater planarians

The aim of this study was to examine whether bisphenol A (BPA) had any effects on the freshwater planarians. It was clarified that the sensitivity to BPA was different in each species. Among these 6 species examined this time, Bdellocephala brunnea showed the highest at 96-h median lethal toxicant concentration (LCsub(50)=9.58 mg/L) and Dugesia ryukyuensis (OH strain) showed the lowest concentration (LCsub(50) = 5.11 mg/L). And it was also recognized that the strained D. japonica (FH strain) has a tendency to die at a lower concentration than the wild D. japonica. After examining the survival rates of three kinds of planarians with three kinds of concentration (100 ppb, 1 ppm, 10 ppm), there was a significant difference in 10ppm treated groups compared with the control specimens, and in D. ryukyuensis and D. japonica even 1 ppm treated groups. We treated D. japonica with a BPA short term lethal concentration (40 ppm) and observed the process to death and classified the process into 6 stages. From these experiments, it was suggested that the specimen has become a non-defensible body as it advanced to the stage 4. We examined the influence of BPA on the regeneration of D. japonica and B. brunnea. In B. brunnea treated with 1 ppm BPA for 4 weeks and 8 weeks after cutting, the head and tail formation failed. We also examined BPA influence on the regeneration of the genital organ using sexual B. brunnea, and we obtained the results that ovaries were growing significantly and the formation of the copulatory apparatus were being stimulated compared with the control specimens in the 100 ppb BPA treated group after 12 weeks. From the results of these experiments, it was clarified that BPA acts like endocrine disrupting chemical when used in a low-level concentration (100 ppb), and it inhibits regeneration when used in a mid concentration (300, 500 ppb and 1 ppm), and it leads them to die in the case of a high concentration (above 1 ppm).