(
http://www.cbsnews.com)
According to a study published August 25 in
Nature Geoscience by researchers from the University of Michigan, mercury produced by coal-burning plants in China and India travel thousands of miles through the air before falling as rain to the ocean floor around Hawaii. From there, it's absorbed by fish that pass it on to humans.
The toxic form of mercury found in fish is called methylmercury. When consumed, it can damage the heart, central nervous and immune system and human fetuses. Scientists previously believed that microbes at the ocean surface were responsible for converting mercury into methylmercury. However, the scientists found that this was not true; they discovered that 80% of methylmercury is produced at depths of about 165 to 2,000 feet, likely by bacteria that cling to sinking organic matter.
The bacteria is consumed by fish and the methylmercury enters the food chain. Fish that live in deeper waters, like swordfish, generally have higher mercury levels. The researchers say that as countries like China and India continue to develop, mercury levels will go up. Dr. David Agus said regarding the study, "[W]e need to push for international controls of mercury in these plants and ways that we can actually degrade the mercury so it doesn't cause a problem to all of us."
