title: Chronic toxicity of bromodichloromethane to the Japanese medaka (Oryzias latipes).
abstract: Japanese medaka (Oryzias latipes) were continually exposed in a flow-through diluter system for 9 months to measured bromodichloromethane (BDCM) concentrations of 0.018, 0.143, or 1.424 mg/L. Parameters evaluated were hepatocarcinogenicity, hepatocellular proliferation, hematology, and intrahepatic BDCM concentration. BDCM was not hepatocarcinogenic to medaka at the concentrations tested. Chronic toxicity was evidenced at 6 and 9 months by statistically significant (alpha = 0.05) levels of gallbladder lesions and bile duct abnormalities in medaka treated with 1.424 mg/L BDCM. Hepatocellular proliferation was assessed after 1, 4, and 20 days of BDCM exposure. Treatment-related increases or decreases in cellular proliferation were not observed at any time point. Hematocrit, leukocrit, cell viability, and cell counts of treated fish after 9 months of BDCM exposure were not significantly different from control fish. Intrahepatic concentrations were evaluated by gas chromatography after 9 months of BDCM exposure. Fish livers from all three BDCM treatments had detectable amounts of BDCM, with median intrahepatic concentrations of 1.02, 2.89, and 21.25 mg BDCM/kg fish liver in the low, middle, and high concentrations, respectively. Medaka chronic toxicity effects of statistically significant gallbladder and bile duct abnormalities occurred at 1.424 mg/L BDCM, well above median drinking water levels.
authors.affiliation: GEO-CENTERS, Fort Detrick, Maryland 21702-5010, USA. Margaret.Toussaint@amedd.army.mil
authors.forename: M W
authors.initials: MW
authors.lastname: Toussaint
authors.forename: A B
authors.initials: AB
authors.lastname: Rosencrance
authors.forename: L M
authors.initials: LM
authors.lastname: Brennan
authors.forename: W E
authors.initials: WE
authors.lastname: Dennis
authors.forename: J R
authors.initials: JR
authors.lastname: Beaman
authors.forename: M J
authors.initials: MJ
authors.lastname: Wolfe
authors.forename: F J
authors.initials: FJ
authors.lastname: Hoffmann
authors.forename: H S
authors.initials: HS
authors.lastname: Gardner
mesh_terms: D000818:Animals; D001652:Bile Ducts / Q000473:pathology*; D002273:Carcinogens / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D005260:Female; D005704:Gallbladder / Q000473:pathology*; D006965:Hyperplasia; D008099:Liver / Q000187:drug effects*; D008297:Male; D009990:Oryzias / Q000254:growth & development*; D013997:Time Factors; D018675:Toxicity Tests; D022882:Trihalomethanes / Q000633:toxicity*
chemical_list: D002273:Carcinogens; D022882:Trihalomethanes; C025191:bromodichloromethane