Thursday, 9 May 2013

PCBs - Dangerous Pollutants in Cities and Rural Areas

PCBs (polychlorinated biphenyls) are dangerous substances that are made and used in industrial processes. They contaminate the environment and enter our bodies in a variety of ways. In experiments with animals the chemicals have been shown to cause cancer as well as problems in the nervous, immune, endocrine and reproductive systems. Research has shown that PCBs harm humans too.

Many people have assumed that people living in industrial cities would have more PCBs in their bodies than people living in rural areas. Now researchers have discovered that the people living in the two habitats have almost the same level of polychlorinated biphenyls in their blood.

Photo by Sturmovik at Wikimedia Commons,
CC BY-SA 3.0 License
Researchers at the University of Iowa analyzed blood samples from people living in East Chicago, Indiana (an industrial area) and in Columbus Junction, Iowa (a rural area). The researchers tested for the presence of all 209 PCB compounds in mothers and their junior high school children. They found that the total level of the chemicals was very similar in each group of people.

The manufacture of PCBs in the United States ended in 1977, although the University of Iowa report says that recently PCB 11, a nerve toxin, has been an "inadvertent byproduct" of paint manufacture. This chemical was found in more than sixty percent of the people that were tested. Polychlorinated biphenyls are stable compounds that persist for a long time, so molecules that contaminated the environment in the past are still present today. The use of PCBs is currently restricted in the U.S.

It's thought that most polychlorinated biphenyls enter our body in our food. They also come from the air that we breathe and the liquids that we drink. They can even pass into our body through skin contact.

The EPA (Environmental Protection Agency) has an interesting web page that summarizes the effects of PCBs on living things. The University of Iowa report doesn't mention how concentrated the PCBs were in the people that they tested, but the results of their survey are still worrying. Polychlorinated biphenyls are definitely chemicals that we need to avoid.