Marion County Health Department spokesman Curt Brantingham says tests didn't pinpoint exactly what the substance was. He says no more testing is planned.
Brantingham says the substance was stirred up Wednesday morning as workers prepared to load a truck and fans dispersed it. Plainfield assistant fire chief Brent Anderson says a worker reported having trouble breathing, and others at the center soon were feeling similar symptoms.
He says 32 workers were taken to area hospitals. He says none of the workers were believed to be seriously ill.
A telephone message seeking comment was left Wednesday for Amazon officials.