In studies with rats, Agricultural Research Service scientists have set the stage for more in-depth research on how livestock animals may handle chemical pollutants ingested from the environment.
Of particular interest is the animals' absorption, breakdown (metabolism), tissue retention and excretion of substances known as "polybrominated diphenyl ethers" (PBDEs), which are flame retardants used in textiles, electronics, plastics and other materials.
PBDEs have been credited with helping prevent fire-related injuries and property damage. But some PBDEs face scrutiny because of their ability to persist in the environment and their potential to accumulate in living organisms, including humans, according to ARS scientists Heldur Hakk, Janice Huwe and Gerald Larsen in Fargo, N.D.
The scientists' studies at the ARS Biosciences Research Laboratory in Fargo aim to shed light on whether PBDEs can be passed from livestock into the food supply. In one approach, the Fargo team fed rats peanut oil containing one of three commercial formulations of PBDEs. The formulation levels used were typical of those found in the environment and included various types of PBDEs.
In another approach, the scientists created radioactive versions of PBDEs and fed them individually to rats. By tracking the radioactivity, the scientists could follow how each substance was absorbed and excreted by the animal.
Among the observations the scientists have made: When exposed to low levels of PBDEs in their food, the rats' gastrointestinal systems absorbed the substances at roughly the same rates, regardless of the size of the PBDE molecules. The group also observed that the rats' bodies did not readily convert the different types of PBDEs into water-soluble forms that could be excreted in urine.
The Fargo group is planning similar studies in chickens. According to Hakk, this research, which will help weigh the benefits of PBDEs' continued use against potential human health issues, augments efforts at federal, state and industry levels.
Annually, fires claim 3,000 U.S. lives and injure 20,000. The total market demand for PBDEs is approximately 67,400 metric tons, according to the Bromine Science and Environmental Forum.
ARS is the USDA's chief scientific research agency.