Kyle Andrew Bessemer, 29, was arrested after he was identified by members of the public when images from surveillance video showing him in a grocery store with a red shopping basket were published online, the F.B.I. and the local police announced on Tuesday.
The authorities said Mr. Bessemer, of Ann Arbor, had intentionally contaminated food in open food bars and produce sections by spraying the items with the mixture at stores, including a Whole Foods Market, a Meijer and a Plum Market, over the last two weeks.
It was not clear if anyone had been sickened by the poison or how it had been detected. The authorities did not provide a motive.
The announcement that someone had randomly doused self-serve food sent a shudder of concern throughout the food industry, which is well aware of the unintentional contamination associated with people serving themselves from common bowls and trays, said Michael Doyle, the director of the Center for Food Safety at the University of Georgia.
Consumers lean in and heap their plates, some without utensils. People sneeze into the food. Some scoop up a little taste with their fingers. Strands of hair, from scalps or beards, can drift down into the serving bowls. Mr. Doyle said his wife once found a Band-Aid in a salad.
“I try to avoid them,” he said, referring to salad bars and buffets.