Final toxicology tests for two unknown powder samples at an Ingram Micro distribution center came back negative, according to an FBI spokesman.
The FBI tested the samples for four toxins including anthrax, the spokesman said.
Ingram Micro evacuated about 400 employees Oct. 15 from its Millington, Tenn., facility after an employee found an unknown, loose white powder in a shipment. After employees returned, another suspicious powder was discovered an hour and a half later, and part of the warehouse was sealed off.
Two Ingram Micro employees were given decontamination showers and antibiotics as a precaution.
Ingram Micro undertook all recommended safety measures following the nationwide wave of anthrax-related scares, said Ingram Micro Chairman and CEO Kent Foster. The incident occurred soon after anthrax spores were discovered at several media and government facilities.
"We're right in the middle of this. Every company in America is in the middle of it," Foster said.
The powder is believed to be residue from disk-drive cleaning kits, said an Ingram Micro spokeswoman.