The research institute RTI International, in conjunction with Duke University in Durham, North Carolina, began a three year study in May, thanks to a USDA grant, to determine whether this type of water is safe to use on food crops. Researchers plan to sample water, soils, and crops from the farms that currently use OPW for irrigation, along with samples from farms that don’t use OPW, then assess any potential human or environmental problems through modeling and risk assessment techniques.