Mead Johnson Nutrition Co. said the finding affected an isolated area of the Zeeland plant. Company spokesman Christopher Perille said plant officials discovered the problem during "normal and detailed monitoring" at the facility.
The plant employs more than 300 workers making Enfamil formula. Details of the finding weren't immediately released.
Perille said follow-up environmental testing found "nothing of concern." Most of the plant wasn't affected.
Full production is expected to resume soon.