By: Duane Craig
A $374 million cleanup of an old Michigan manufacturing site has resurrected bad memories from more than 40 years ago when one of the worst agricultural contamination cases caused the destruction of 30,000 cows and introduced a dangerous contaminant into the human food chain.
The contaminant responsible was polybrominated biphenyls, or PBB, a flame retardant produced by Michigan Chemical in St. Louis, Mich. In 1973 the company was making PBB as well as magnesium oxide, a supplement for cattle. Somehow, the two got mixed together and the contaminated supplement was fed to cattle across the state. Almost immediately cattle began losing weight, growing deformed hooves, and "developing abscesses and elephant-like hides." It was months before the state discovered the cause and quarantined more than 500 farms. In the meantime, nine out of 10 residents in the state consumed PBB in milk and other food products derived from cattle. Not only were 30,000 cows destroyed, but also an estimated 1.5 million chickens and thousands of pigs, sheep and rabbits that had either eaten the PBB directly or eaten food made with animal renderings that was contaminated with the material.
The animals were buried in two huge burial pits that have been monitored for seepage since they were backfilled. So far there have been no leakages of PBB from the burial grounds. Some of the state’s rivers have detectable levels of PBB, but not at concentrations the Michigan Department of Community Health considers to be risky.
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