PBBs Michigan

The principal source of pollution by polybrominated biphenyls (PBBs) has been the commercial mixture Firemaster, which was produced in the United States between 1970 and 1974. Production was discontinued in 1974 following a severe pollution incident in Michigan, when Firemaster was accidentally mixed with cattle feed on a farm. In due course, PBBs entered the human food chain via contaminated animal products. Substantial residues were found in humans from the area, and were snbse-quently found to be highly persistent. 

Firemaster is a stable solid, resembling a PCB mixture in its lipophilicity, chemical and thermal stability, and low vapor pressure. Firemaster contains some 80 ont of a possible 209 PBB congeners, but just two of them— 2,2, 4,4, 5,5-hexabromobiphenyl and 2,2, 3,4,4, 5,5, heptabromobiphenyl—account for around 85% of the commercial product (Environmental Health Criteria 152). These two componnds were fonnd to be very slowly eliminated by humans exposed to them during the Michigan incident. A half-life of abont 69 weeks was estimated for 2,4,5,2,4, 5 -HBB. 

Chou, S.H. Fate of Acylanilides in Soils and PolybrominatedBiphenyls (PBBs) in Soils and Plants, Dissertation, Michigan State University, East Lansing, MI, 1977. 

A group of 55 workers who had been employed in the Michigan plant producing FireMaster BP-6 from 1970 to 1974 were examined, and all were found to have serum levels of PBBs greater than lmg/1. An increased prevalence of respiratory symptoms and skin disorders was seen in this group compared with the available data on PBB-exposed farmers lin Michigan. 

Polybrominated biphenyls (PBBs) Contaminant Fire retardant inadvertently substituted for feed supplement in Michigan livestock loss, undetermined effect on human health... 

PBBs are no longer produced or used in the United States. Thus, the general population exposure to PBBs will only be from past releases. For people residing in the lower peninsula of Michigan, especially near PBB contaminated areas, exposure to PBBs may still be occurring today. However, environmental levels have decreased since the 1970s and current exposure, if any, will be at low levels. For other regions of the United States, the levels of exposure will either be very low or none. 

Some information on health effects of PBBs in children is available from studies of the Michigan contamination episode. Symptoms of ill health were not associated with increased exposure to PBBs and general neurological examinations did not show any abnormalities. More detailed... 

Limited data are available on health effects of commercial decabromobiphenyl and octabromobiphenyl mixtures, although the hexabromobiphenyl mixtures FireMaster BP-6 and FireMaster FF-1 have been extensively tested. Most of the information on human health effects of PBBs comes from studies of Michigan residents who accidentally ingested milk, meat, and eggs that came from farms that used animal feed contaminated with FireMaster FF-1. In 1973, livestock on certain farms in Michigan were exposed to... 

Examinations of a small number of children (19) believed to have been exposed in utero or in early infancy during the peak of the Michigan PBB-feed contamination episode have not found consistent or marked effects on neuropsychological development. One study found a statistically significant association between performance in neuropsychological development tests and PBB levels in adipose tissues when the children were 2.5-4 years old, but a later examination when the children were 4-6 years old did not find such an association for the same tests. 

Polybrominated Biphenyls. Symptoms of musculoskeletal effects, described as "joint pain" and "swelling in joints," were frequently cited health complaints in two epidemiological studies of groups of Michigan residents who were likely to have ingested PBB-contaminated food (Anderson et al. 1978c Landrigan et al. 

Although one study demonstrated a statistically significant difference between the prevalence rate for these types of symptoms in Michigan residents compared with nonexposed residents of Wisconsin farms (Anderson et al. 1978c), neither study demonstrated a positive association between serum PBB levels and the prevalence rates for symptoms of musculoskeletal effects. 

Polybrominated Biphenyls. Results from several studies of humans exposed to PBBs do not demonstrate, in general, a conclusive association between adverse effects on the liver and oral exposure to PBBs. In a study in which serum was collected in 1974, 1977, 1978, and 1979 from 89, 240, 220, and 200 individuals, respectively, who were predominately residents of quarantined Michigan farms, no consistent statistically significant correlations were found betw een serum PBB levels and levels of serum glutamic oxaloacetic transaminase (SGOT), serum glutamic pyruvic transaminase (SGPT) or serum bilirubin (Kreiss et al. 

Polybrominated Biphenyls. No statistically significant correlations were found between serum PBB levels and serum levels of blood urea nitrogen (BUN) or creatinine in a study of residents of quarantined Michigan farms after the 1973 PBB contamination episode (Kreiss et al. 1982). No other studies were located with information pertinent to renal effects in humans after oral exposure to PBBs. 

Polybrominated Biphenyls. Numerous reports have been published regarding the immunological competence of individuals exposed to PBBs in the Michigan feed contamination episode. Due to the relatively high number of published reports and to the fact that often different groups of investigators appear to have examined the same cohort, only representative studies are discussed below. 

It was also reported at this time that Michigan farm residents with the highest exposure to PBB had significantly elevated levels of IgM, IgA, and IgG relative to Wisconsin dairy farm residents (Bekesi et al. 

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