PARENT SESSION
PW2 - The Japanese Medaka Model
Wednesday, 20 November 2002
8:00 AM to 6:30 PM
Exhibit Hall
(P736) Acute Toxicity and Effects of Methylene Chloride on Egg Hatchability and Fry Survival of Japanese Medaka (Oryzias latipes).
Ahmd, Bashir*,1, Thiyagarajah, Arunthavarani1, Watanabe, Karen1, Hartley, William1, Abdelghani, Assaf1, 1 Tulane University Health Sciences Center and Center for Bioenvironmental Research, New Orleans, LA, USA
ABSTRACT- Methylene chloride is one of the chemicals found commonly in the contaminated environment. The purpose of this study is to determine the acute and embryotoxic toxic effects of methylene chloride. A 96-h acute toxicity studies were performed on the embryos in duplicate. The LC 50 was 875 mg/L methylene chloride with lower and upper 95% confidence intervals of 825 and 925 mg/L respectively. The embryo toxicity experiments are currently in progress. The embryos at early high blastula stage were exposed to five concentrations (0, 125, 250, 375, 500 and 625 mg/L) and two environmentally relevant concentrations of methylene chloride for 10days, then transferred to contaminant free water, and allowed to hatch. An average of 68 ppb of methylene chloride in surface water and 98 ppb methylene chloride in groundwater have been found at some hazardous waste sites. Less than 1 ppb has been found in most drinking water analyzed. Therefore the environmentally relevant concentrations selected were 0.1 mg/l and 0.01 mg/L. Fry were monitored for mortality for 2 weeks. Then the fry were transferred to grow-out tanks. The endpoints evaluated were mortality, egg hatchability and fry survival. The results will be discussed. Funded in part by Department of Energy project number # DE-FC26-00NT40843
Key words: Methylene chloride, Medaka, Acute Toxicity, Embryotoxicity