Effects of PBBs on Cattle. IV. Distribution and Clearance of Components of FireMaster BP-6

Abstract

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. The National Institute of Environmental Health Sciences (NIEHS) and Brogan & Partners are collaborating with JSTOR to digitize, preserve and extend access to Environmental Health Perspectives.Sixty dairy animals were utilized in seven experiments to determine aspects of the distribution and clearance of FireMaster BP-6. Experimental protocols of various studies provided daily exposures from 0.25 to 25,000 mg, exposures for I to 202 days, and total study periods from 10 to 1100 days. Necropsy of 28 animals provided information on residue concentrations in 35 tissues, and the excretion in milk was determined in 15 animals. These studies showed that the major brominated biphenyls of this commercial mixture were absorbed from the gastrointestinal tract and appeared in the blood plasma within 4 hr. With continued exposure to the residue plasma concentrations reached a steady state by 15 days. Free PBB was not detectable in urine. During PBB feeding feces was the major route of excretion, representing approximately 50% of the amount fed to animals not displaying signs of toxicosis. Following withdrawal of PBB, fecal concentrations declined to 1 to 2% of concentrations during dosing, yet, feces remained the major excretory route in nonlactating animals. In contrast, in post-exposure lactating animals milk fat became an important excretory route removing three-times the quantity of residue cleared in feces. Following parturition, concentrations of PBB in milk fat declined approximately twofold in 6 days. Thereafter, the residue concentration in milk fat was approximately 0.4 that in depot fats. PBB had a predilection for lipid tissues with similar concentrations in various depot fats. Concentrations of the residue were notably low in tissues of the nervous system despite the high content of lipid material. Liver contained residue concentrations that were disproportionately high when compared to the lipid content of the organ. Calves born to PBB-exposed cows had similar distribution of residues in body tissues although concentrations were less than those of the dam.

PBB homologs in sera of Michigan dairy farmers and Michigan chemical workers.

“…In rats, the 2,3,4,5,2',4',5'-heptabromobiphenyl is readily absorbed along with other PBB components and persists unchanged for long periods (22). Absorptionexcretion patterns of heptabromobiphenyls in man and in cattle are apparently different from the rat, at least over the long term (23). (Willet et al, in press).…”

Effects of PBBs on cattle. III. Target organ modification as shown by renal function and liver biochemistry

“…These data support the previous conclusion by Durst et al (4) that PBB is a threshold toxin (29) in cattle and must be encountered in high concentrations before toxic responses are elicited. Other related work on the effects of PBBs in cattle is summarized in the accompanying papers (18,30,31). From these studies, it is apparent that large animals are useful and reliable for studying xenobiotic effect, distribution, and clearance.…”