Francisco Ramirez, a 31-year-old gardener who had been visiting family in the central California city of Bakersfield, was allowed to return home to Milwaukee.
"The substances in the bottles did turn out to be honey. They tested negative for all explosives and narcotics. It is nothing but honey," said FBI spokesman Steve Dupre.
The security scare came as jitters gripped the U.S. travel industry in the aftermath of an unsuccessful Christmas Day attempt to blow up a Detroit-bound commercial flight from Amsterdam using explosives smuggled on board.
Meadows Field Airport in Bakersfield, about 160km north of Los Angeles, was shut down and evacuated for hours and flights diverted after the incident, which began when Ramirez' bag set of an alarm in a luggage-screening machine.
US Transportation and Security administration screeners turned up five Gatorade bottles full of what they called a "suspicious-looking liquid." Swabs of the bag and bottles tested positive for the explosives TNT and TATP.
When the bottles were opened, two of the screeners smelled a strong chemical odor, complained of nausea and were rushed to a local hospital, where they treated and released, Kern County Sheriff's spokesman Michael Whorf said.
Kern County Sheriffs deputies, fire crews, FBI agents and members of a "joint terrorism task force" responded to the scene and spent the day questioning Ramirez before further tests showed that the liquid was honey.
After the all-clear was given, officials said they were trying to determine why the honey tested positive for explosives and made the screeners so ill that they would need medical attention.
"There are some questions I think are going to have to be followed up on," Dupre said. He said that Ramirez was "free to go" and would likely be home in Milwaukee by Wednesday.
Ramirez, who Whorf described as "very cooperative," had originally been booked on a flight from Bakersfield to Milwaukee with a connection through San Francisco.
In an unrelated incident halfway across the country on Tuesday, a bomb-sniffing dog detected what was thought to be explosives in a piece of luggage at the Minneapolis-St. Paul International Airport, prompting an evacuation of a terminal and delayed flights there.
No explosives were found in the bag.
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