PBB

From Great Lakes Wiki

Polybrominated biphenyls, or PBBs, are a group of flame retardants used in home appliances and other plastics to make them more difficult to burn. In 1973, Michigan Chemical Co., the owner of a chemical plant in St. Louis, accidentally mixed PBB with livestock feed, leading to one of the worst widespread contaminations in U.S. history. That location on the Pine River is now closed, and is maintained as the Pine River Superfund Site.

Before the 1970s, PBBs were widely used commercially as a flame retardant. In 1973, however, several thousand pounds of PBBs were accidentally mixed with livestock feed that was distributed to farms in West Central Michigan, USA. Some 1.5 million chickens, 30,000 cattle, 5,900 pigs, and 1,470 sheep had become contaminated with PBBs before the error was discovered. These events were dramatized in the 1981 film Bitter Harvest.

Although these animals were promptly culled, a study was undertaken on 4,545 people to determine the effects of PBBs on human beings. These include three exposure groups – all people who lived on the quarantined farms, people who received food from these farms and workers (and their families) engaged in PBB manufacture – as well as 725 people with low-level PBB exposure.

All were queried concerning 17 symptoms and conditions possibly related to PBBs. Venous blood was drawn and analyzed for PBB by gas chromatography. Mean serum PBB levels were found to be 26.9 ppb by weight (26.9 µg/kg) in farm residents, 17.1 in recipients, 43.0 ppb in workers, and 3.4 ppb in the low exposure group. No associations could be established between serum PBB levels and symptom prevalence rates.

Noting the possible hazards on the environment, however, PBBs were listed as one of six controlled substances under the Restriction of Hazardous Substances Directive (ROHS), which was enacted into European Law in February 2003. Partly as a market-driving phenomenon, ROHS legislation lists PBBs as a "restricted substance" group, resulting most recently in restriction dates planned in China on March 1, 2007 and South Korea on July 1, 2007.

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This page (PBB) is (all or in part) copied from Wikipedia. It is therefore licensed under the GNU Free Documentation License version 1.2. It uses or incorporates material from the Wikipedia article Polybrominated_biphenyl.