A man is in custody after he admitted to spraying a contaminant that officials believe contained mice poison on unpackaged food at several Michigan grocery stores, the FBI said.

In a news release Tuesday, the FBI said an investigation indicates the man sprayed a mixture of hand cleaner, water and mouse poison on produce and open food bars at three Ann Arbor stores within the last couple weeks.

The FBI said an investigation is ongoing to determine if other stores the suspect visited were affected.

State officials said they don't anticipate adverse health effects for those who may have eaten potentially contaminated food. But customers were encouraged to throw away food from salad bars, olive bars and ready-to-eat hot and cold food areas at the affected stores.