The Pbb Episode in Michigan: An Overall Appraisal

Abstract

Polybrominated biphenyls (PBB) were used as a fire retardant. In common with other halogenated hydrocarbons, PBBs are lipophilic and resistant to chemical and metabolic degradation. Cattle on about 25 Michigan farms were exposed to as much as 250 g per head of PBB when it was accidentally mixed in cattle feed in 1973 to 1974. Livestock exposures several orders of magnitude lower occurred on several hundred other farms because of carryover and equipment contamination in feed mills. Approximately 85% of the Michigan population received some exposure to PBB because dairy product marketing involves mixing milk from many farms. A few cases of high human exposure, which may have been as great as 10 g, occurred when residents of the more highly exposed farms consumed their own products. Although numerous clinical signs and pathological changes were reported in exposed cattle, only anorexia, lacrimation, emaciation, hyperkeratosis, and kidney damage were confirmed in controlled studies. The acute toxicity of PBB in laboratory animals is low, but a variety of subacute effects have been reported. Induction of microsomal enzymes, enlargement and histopathological changes of the liver, fetotoxicity, and immunosuppression are among the more significant. Epidemiological studies of exposed humans have revealed no pattern of clinical signs or symptoms that were related to PBB exposure. A complete evaluation of the human consequences of exposure to PBB await the conclusion of long-term epidemiological studies.

Association of Brominated Flame Retardants With Diabetes and Metabolic Syndrome in the U.S. Population, 2003–2004

“…Unlike PBDEs, PBBs were prohibited in the U.S. in the 1970s after an accidental human exposure in Michigan (15). Thus, their main exposure route would be diet, which is similar to that for chlorinated POPs (15). These different exposure routes were reflected in the correlations among serum BFR concentrations.…”

“…Humans are exposed to PBDEs in house dust in direct inhalation, ingestion, and dermal exposure (5). Unlike PBDEs, PBBs were prohibited in the U.S. in the 1970s after an accidental human exposure in Michigan (15). Thus, their main exposure route would be diet, which is similar to that for chlorinated POPs (15).…”

Estimating perchlorate exposure from food and tap water based on US biomonitoring and occurrence data

“…2,2',4,4',5,5'-hexabromo biphenyl (BB-153) is a brominated biphenyl that was used as a flame retardant in the U.S. until the 1970s. Its use was phased out following an accidental contamination of cattle feed in the state of Michigan with the contamination extending to other animals, the environment, and into humans (Fries, 1985).…”

The Caffeine Breath Test and Caffeine Urinary Metabolite Ratios in the Michigan Cohort Exposed to Polybrominated Biphenyls: A Preliminary Study

“…Contamination of the Michigan food chain with polybrominated biphenyls (PBBs) occurred between July of 1973 and May of 1974 when approximately 295 kg of a mixture of PBB congeners, manufactured as a flame retardant (FireMaster FF-1), was accidentally added to dairy cattle feed (1,2). The contaminated feed was subsequently shipped to farms and retail outlets in Michigan, resulting in the dissemination of the PBBs in the Michigan food chain.…”