Distribution and excretion of 2,4,5,2’,4’,5'‐hexabromobiphenyl, the major component of firemaster BP‐6

Abstract

The intestinal absorption, distribution, and excretion of the major component of Firemaster BP-6,2,4,5,2',4',5'-hexabromobiphenyl, has been studied in the male rat. This polybrominated biphenyl was readily absorbed from the intestine, initially distributed throughout the body, and eventually stored primarily in the adipose tissue, was not subject to appreciable metabolism, and was excreted almost exclusively in the feces and at a very slow rate. Approximately 90% of an oral dose was absorbed from the intestine, and extrapolation of the rate of excretion to infinity indicates that less than 10% of the total dose would ever be excreted.

Toxicity of polybrominated biphenyls (PBBs) in Domestic and laboratory animals.

“…Similar relationships have been reported for the PCBs (48,49). The major technical hexabromobiphenyl component, 2,4,5,2' ,4',5'-hexabromobiphenyl, appears to be the most persistent component in the species studied (26,27,43).…”

“…It was estimated on the basis of the short-term metabolic studies that only 9.5% of the total dose would ever be excreted in the feces. These findings suggested that male and nonnursing females and non-egglaying birds would be unable to effectively clear Environmental Health Perspectives their tissues of ingested PBBs in their lifetimes (43). There is evidence that another PBB component, heptabromobiphenyl, disappears more quickly from milk (36) and eggs (38) than the hexabromobiphenyl described above.…”

“…These studies indicate that PBBs are rapidly and almost completely absorbed (absorption apparently decreases with increasing bromine con-177 tent) from the gastrointestinal tract and are initially distributed widely throughout the body tissues with major concentrations in liver and fat (1,5,(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44). Based on the available data, the PBBs in Firemaster BP-6 are apparently metabolized to give hydroxylated degradation products by metabolic routes that are similar to those for the structurally related polychlorinated biphenyls (14,(45)(46)(47)(48).…”

“…Additional excretory routes for these chemicals are via lipophilic secretions such as hair and skin oil. Milk and eggs are the major routes in lactating mammals and egg-laying birds, respectively (43). Transplacental transfer of PBBs has been demonstrated in rats and cows and detrimental effects in young suckling on PBB-contaminated mothers have been reported (5,29,37,(40)(41)(42).…”

The role of structure in the disposition of halogenated aromatic xenobiotics.

“…Matthews and Anderson (17) showed that 2,4,5,2',4',5'-hexachlorobiphenyl was metabolized and cleared very slowly. The same brominated isomer, which is a major component of Firemaster BP-6 (9), was also shown to be resistant to metabolism (18). After treating rats with Firemaster FF-1, Domino et al (56) showed that 2,4,5,2',5'-pentabromobiphenyl was cleared more rapidly than was 2,4,5,3',4'-pentabromobiphenyl.…”