T9 AM Bioaccumulation and Biomagnification
Tuesday, 15 November 2005: 8:00 AM - 11:40 AM in 339-340

(STA-1117-829501) Uptake and Debromination of Decabromodiphenyl Ether in Juvenile Rainbow Trout: Assimilation and Biotransformation.

Stapleton, H¹, Brazil, B², Holbrook, R¹, Anderson, S², ¹ National Institute of Standards and Technology, Gaithersburg, MD, USA² National Center for Cool and Coldwater Research, Kearneysville, WV, USA

ABSTRACT- Decabromodiphenyl ether (BDE 209) is the major component of the commercial flame retardant mixture known as decaBDE, which is commonly used to flame retard polymers such as high impact polystyrene found in TV and computer casings. High concentrations of BDE 209 have been reported in sediments, biosolids and house dust. The present study was undertaken to examine the in vivo uptake and biotransformation of BDE 209 by juvenile trout along the gut wall that would lead to accumulation in other tissues within trout. Juvenile rainbow trout were reared at the U.S. Department of Agricultures National Center for Cool and Coldwater Aquaculture. One tank was fed a clean control diet throughout the experiment and three tanks were fed food spiked with decabromodiphenyl ether (BDE 209) at a rate of 9.4 micrograms/kg body weight/day. The concentration of BDE 209 in fish tissues from the exposure tanks increased throughout the first four months of exposure from 1.4 ng/g wet weight to 9.6 ng/g wet weight. NonaBDEs were measured in trout tissues after one week of exposure and octaBDEs were observed in the second week of exposure. Five octaBDE congeners, including BDE 196, BDE 197 and BDE 203 were observed to increase in concentration throughout the dietary exposure to BDE 209. Four heptaBDE congeners, including BDE 183, also increased in concentration throughout the exposure period. Only one hexaBDE congener, BDE 154, appeared to increase in concentration. Results from the first month of the present experiment demonstrate that the concentration of PBDEs was consistently higher in the intestinal and gut tissues relative to the carcass of the rainbow trout. Concentrations were 5 to 20 times higher in intestinal tissue relative to the whole body tissue. BDE 209 and minor levels of nonaBDEs were detected in the residual food recovered from the rainbow trout guts upon sacrifice. Based on this evidence, it appears that the formation and accumulation of octa- and heptaBDEs occurs at the gut wall. Work is currently in progress with intestinal and liver microsomes to assess the potential for debromination of BDE 209 and to compare the biotransformation of BDE 209 observed in vivo, to the in vitro experiments.

Key words: PBDEs, debromination, biotransformation, rainbow trout