What Can We Learn from Environmental Accidents?

Accidents happen. When they do, it is important to learn from them. Environmental accidents teach society about the dangers of certain chemicals or industrial processes. In 1973, a major chemical accident occurred in Michigan, USA. A chemical company there manufactured both polybrominated biphenyls (PBBs) and a food supplement for farm animals. PBBs are chemicals once used to reduce the flammability of plastics and other materials. The company made a critical mistake. It accidentally sent bags of PBBs to be mixed into animal feed, instead of the intended food supplement.

The contaminated feed was distributed to farms across Michigan. The contamination was not discovered until a year later, after a farmer spent months investigating why his cows were getting sick. By that time, millions of people in Michigan had unknowingly eaten meat, dairy products, and eggs from animals that had consumed PBBs.

Scientists have spent decades studying the health effects of this accident. In this article, we review their findings. We summarize the short-term and long-term health effects on the people who were exposed. We also examine how the accident affected their children and even their grandchildren.

Some chemicals designed to improve life can turn out to be dangerous. Polybrominated biphenyls (PBBs) are a prime example. These chemicals were widely used in the 1970s to make products like plastics and textiles less flammable. However, their use was banned in 1976. Why? People discovered that PBBs are persistent organic pollutants. They break down very slowly and can remain in the environment and in people's bodies for a very long time, causing negative health effects.

The dangers of PBBs became widely known because of the 1973 Michigan accident. For nearly a year, livestock such as cows, chickens, and hogs ate feed contaminated with PBBs. People then consumed the milk, meat, and eggs from these animals. It is estimated that up to 6.5 million people were exposed.

Since the accident, scientists have conducted numerous studies. We wanted to understand exactly how much we know about the human health effects of PBBs. We systematically reviewed scientific studies focused on people affected by the Michigan contamination. Our goal was to summarize what we have learned.