U.S. Rep. Russ Carnahan has announced two fresh investigations into the use of improperly sterilized medical equipment at the Cochran Veterans Administration hospital in midtown St. Louis.

The VA's inspector general, Carnahan said in a news release this morning, has agreed to launch a formal investigation into why dental equipment at the facility was not properly cleaned, potentially exposing veterans to hepatitis and other communicable diseases.

At the same time, the General Accounting Office -- a watchdog agency that takes its orders from Capitol Hill -- will include Cochran into an existing investigation focused the processing of reusable medical equipment at several VA hospitals around the country.

The VA sent letters in late June to those who had dental procedures at Cochran from Feb. 1, 2009, through March 11, 2010. advising them of the need to be tested. The warning touched off an outcry from some veterans, prompted congressional criticism and led to the chief of the dental clinic being placed on leave.

"These independent investigations are critical to make sure we have a full understanding of what happened so we can identify and fix any systemic problems that made such a grave error possible," Carnahan said in a statement.