Study: U.S. crude oil less toxic than coal

Tomball, Texas -- U.S. scientists have completed a four-year study of mercury in U.S. refined crude oil and found it contains less toxic mercury than does coal on average.

S. Mark Wilhelm and colleagues at Mercury Technology Services in Tomball, Texas, said extensive studies have been conducted on mercury in coal, the nation's other major fuel. Coal is the largest source of human-generated mercury emissions in the United States, with coal-fired power plants releasing about 48 tons of mercury annually, according to U.S. Environmental Protection Agency figures.

However, the amount of mercury present in crude oil, and thus potentially released into the air in automobile exhaust and other sources, remained uncertain due to a lack of accurate mercury concentration data for the wide range of crude oils produced domestically and imported into the United States.

The researchers found the total amount of mercury in crude oil processed in the United States annually is less than five percent of the amount contained in U.S. coal.

The full study is to appear in the July 1 issue of the journal Environmental Science & Technology.

Copyright 2007 by United Press International.