Chapel Hill, N.C. — Democratic presidential hopeful John Edwards' campaign office in Chapel Hill was to reopen Thursday after an evacuation prompted when a staff member opened an envelope containing white powder.

Authorities tested the substance and found that it didn't pose a health threat, according to a news release issued by the campaign Thursday morning.

“The test results of the white powdery substance received (Wednesday) have come back negative, and the authorities have informed us that it is safe to return to the office," the statement said.

The office is located in the commercial center of Southern Village, but other businesses in the area weren't affected.

Edwards, who resides in Chapel Hill, was out of town Wednesday, speaking at Howard University in Washington, D.C.

White powder in letters has been associated with anthrax after an attack in 2001 killed five people and sickened 17. The substance was mailed to lawmakers on Capitol Hill and members of the news media in New York and Florida just weeks after the Sept. 11, 2001, terrorist attacks.