Authorities are trying to find who dumped medical waste that includes syringes and vials in the Arkansas River in eastern Oklahoma.

Oklahoma Department of Environmental Quality spokeswoman Skylar McElhaney said Tuesday that a "significant amount" of waste had been discovered in the past few days washed up near Ralston. She says it's not known what was in the vials or syringes. Patient ID bracelets were also found.

She says some waste had names of patients and medical facilities on them. She warned fisherman and others who come to that area for recreation that there's still a risk of getting stuck with needles that haven't been recovered. Officials say there's no risk to drinking water.

The Pawnee County Sheriff's Office is also investigating. A message left seeking comment wasn't immediately returned.