目的：本研究主要探討常用植物生長調節劑(Gibberellic acid, Paclobutrazol)對水生生物可能造成的傷害。方法：採用已建立之研究生態毒理學模式，研究室自行培養五代以上之圓水蚤(Daphnia pulex)為測試生物，試驗之測試藥劑皆以仿自然水體溶液為稀釋水配製系列濃度測試溶液，於每次實驗前進行配製使用。檢驗植物生長調節劑（勃激素、巴克素）是否對水蚤生活史有影響。包括圓水蚤(Daphnia pulex)急毒性試驗評估樣本半數致影響濃度值(EC50 value)，與胚胎毒性試驗評估致畸胎之EC50濃度值。結果：植物生長調節劑的急毒性試驗結果發現，勃激素A3與巴克素對圓水蚤會造成傷害導致死亡；胚胎毒性試驗顯示植物生長調節劑會對圓水蚤胚胎造成致畸胎現象；勃激素A3可導致圓水蚤胚胎造成致畸胎現象的最低閾值濃度是0.5 mg/L；巴克素則是0.2mg/L。致畸胎的現象包括殼刺彎曲、觸角分化不完整、馬氏管分化不完全，並且隨著藥劑濃度增加致畸胎情形越為嚴重。結論：試驗結果證實本研究之假設，市面上常見的植物生長調節劑對水生無脊椎動物是有害的。暴露於勃激素A3及巴克素之圓水蚤胚胎相較於控制組，有死亡、生長遲滯或生長畸型等現象。
Purpose: The present study evaluated whether the plant growth regulators, gibberellic acid and paclobutrazol, would be embryotoxic to cladoceran Daphnia pulex (water fleas) in the laboratory. Methods: For this study, we developed an in vitro assay system to detect toxic compounds in the aquatic environment containing 5th generation water flea (cladoceran) eggs. The eggs were placed in a culture medium containing nature-imitating water (hard water). Then, two representative plant growth regulators, gibberellic acid and paclobutrazol, were added at various doses in a series of experiments in which we performed acute toxicity tests for EC50 values and evaluated embryo toxicity by observing the occurrence of visible morphological embryonic abnormalities. Results: We found gibberellic acid and paclobutrazol to be toxic to developing embryos. The threshold concentration of gibberellic acid for the occurrence of developmental abnormalities was 0.5 mg/L and paclobutrazol 0.2 mg/L. The developmental abnormalities consisted primarily of curved or unextended shell spines, underdeveloped first antennae, and underdeveloped Malpighian tubes. The greater the exposure to the chemicals, the greater the incidence of these abnormalities. Conclusion: Gibberellic acid and paclobutrazol are embryotoxic to daphnids and cause growth retardation, abnormalities and death.
