"Long considered one of the nation's most dangerous industries, oil refining suddenly seemed one of the safest when the U.S. Bureau of Labor Statistics reported no refinery deaths in 2002 or 2003. But at least nine people were asphyxiated, burned or fell to their deaths at our nation's refineries during those years, according to a Houston Chronicle review of media accounts, industry statistics and fatal accident reports to the Occupational Safety and Health Administration. Twenty more have died since then — 15 in the March 23 BP Texas City accident alone.
How do the refinery dead disappear?
The answer is fairly simple. Increasingly, the accuracy of government safety statistics is undermined by the changing work force. These days, up to half of refinery workers are contractors, who generally get some of the most dangerous jobs. Since these folks do not work directly for petroleum companies — even though some toil for years at the same refinery — their deaths get diverted to several catch-all construction or maintenance categories, such as "1799, Special Trade Contractors, Not Elsewhere Classified."
"They'll show up in the statistics but not as refinery workers," explained retired Bureau of Labor Statistics (BLS) economist Guy Toscano. "The more dangerous an occupation, the less likely a company would want to hire those people directly — they want to boost their own safety rates and decrease their liability."
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http://www.chron.com/cs/CDA/ssistory.mpl/metropolitan/3183356