WASHINGTON - FEBRUARY 4: An EPA employee walks towards a stack of 55 gallon drum barrels in a staff parking lot near the Dirksen Senate building, which remains closed February 4, 2004 in Washington, DC. Three Senate office buildings were closed February 2 after a letter was confirmed to contain the poison ricin in Senate Majority leader Bill Frist's (R-TN) office. (Photo by Mannie Garcia/Getty Images)
