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In a new study conducted by the U.S. Geological Survey (USGS), every single fish tested
from 291 freshwater streams across the United States was found to be contaminated with
mercury.
"This study shows just how widespread mercury pollution has become in our air,
watersheds and many of our fish in freshwater streams," said Interior Secretary Ken
Salazar.
Mercury is a potent neurotoxin that builds up in the food chain at ever higher
concentrations in predators such as large fish and humans. It is especially damaging to
the developing nervous systems of fetuses and children, but can have severe effects on
adults, as well. The pollutant enters the environment almost wholly as atmospheric
emissions from industrial processes, primarily the burning of coal for electricity. It
then spreads across the plant and settles back to the surface, eventually concentrating in
rivers, lakes and oceans, where it enters the aquatic food chain.
The number one cause of human mercury poisoning in the United States is the consumption of
fish and shellfish.
Researchers tested the water, sediment and fish of the 291 streams between 1998 and 2005.
Fish tested were mostly larger species near the top of the food chain, such as largemouth
bass.
All fish were contaminated with mercury, more than 66 percent of them at levels higher
than those set by the Environmental Protection agency as a "level of concern for
fish-eating mammals," according to Reuters. More than 25 percent of the fish were
contaminated at levels higher than those set as the threshold for human consumption.
The study is the first to focus on mercury contamination of streams, rather than lakes,
reservoirs, wetlands or oceans. The researchers found the highest mercury concentrations
in fish from the coastal blackwater streams of the Southeast. Apparently the combination
of pine forests and wooded wetlands found in these regions transforms mercury very
effectively into its more toxic organic form (methylmercury). Mercury concentrations were
also high in streams fed from areas with a history of mining. (Natural News, 3.03.2010) http://www.naturalnews.com/028284_fish_mercury.html
Sources for this story include: www.reuters.com.
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