Toxicity Studies of Chlorpyrifos to Leopard Frog (Rana pipiens) Embryos

EPA Grant Number: U915585
Title: Toxicity Studies of Chlorpyrifos to Leopard Frog (Rana pipiens) Embryos
Investigators: Gaizick, Lia M.
Institution: University of Maryland - Eastern Shore
EPA Project Officer: Hahn, Intaek
Project Period: September 1, 1999 through January 1, 2001
Project Amount: $61,220
RFA: STAR Graduate Fellowships (1999) RFA Text |  Recipients Lists
Research Category: Academic Fellowships , Endocrine Disruptors , Fellowship - Endocrine Disruptors


The objective of this research project is to determine the effective concentration (EC50) of chlorpyrifos (CPF) to Rana pipiens embryos. Specific interests include determining the sensitivity of embryonic life stages (Gosner stages 12-20) of R. pipiens to CPF, and performing comparative studies using Daphnia magna neonates and Vibrio fischeri (using the Microtox assay).


Standard acute toxicity tests (96 hours) were conducted on R. pipiens embryos in an environmental chamber. Water temperature remained at 19°C. At the conclusion of the 96 hours, we examined effects such as hatching time, hatching success, and physical malformations such as edema, skin discoloration, and curvation of the tail. Glass finger bowls (105 mm x 44 mm) served as test chambers. Each bowl had 10 embryos. Test concentrations were 0, 10, 50, 100, and 200 ppb CPF, with tests being run in triplicate. Dissolved oxygen, temperature, pH, and water hardness were monitored. A 2 mg/L CPF stock solution was used to make dilutions with reconstituted spring water. No carrier solvent was used to reduce toxic carryover effect from solvent. Chlorpyrifos concentrations were analyzed at the beginning and end of the 96-hour tests. D. magna static, acute-toxicity tests of 48 hours were followed according to procedures outlined in Standard Methods for the Examination of Water and Wastewater. The Microtox assay also was conducted, using the organic-solvent test protocol.

Supplemental Keywords:

fellowship, chlorpyrifos, amphibians, Microtox., RFA, Health, Scientific Discipline, Environmental Chemistry, Endocrine Disruptors - Environmental Exposure & Risk, endocrine disruptors, Environmental Microbiology, Biochemistry, Biology, Endocrine Disruptors - Human Health, aquatic ecosystem, microbial degradation, wastewater, EDCs, endocrine disrupting chemicals, chlorpyrifos, estrogen response

Progress and Final Reports:

  • 2000
  • Final