Verso Corp. says the chemical that spilled into the Potomac River last week at its Maryland paper mill was a synthetic form of latex, posing no allergy threat for people sensitive to natural rubber.
Verso spokeswoman Kathi Rowzie said Monday the substance was half water and half styrene-butadiene, a paper coating. Nearly 10,000 gallons spilled into the river Wednesday from a wastewater treatment plant serving the mill in Luke.
Rowzie says workers failed to close a drain from a storage tank that was being filled from a railroad tank car.
The spill prompted Paw Paw, West Virginia, to close its water intake Sunday before the milky green plume arrived. The town stored enough water to supply customers until Tuesday morning, when experts say the plume will have passed.