Fluorescein is a non-toxic substance typically used for testing wastewater systems. The results, however, "did not demonstrate the presence of toxic elements in the samples analyzed," Arpav said.
The change of color had been reported by residents, raising many questions. In 1968, the Argentine artist Nicolas Garcia Uriburu dyed his waters green with a fluorescent dye during the 34th Venice Biennale, as part of an ecological awareness campaign.. Activists from the last generation environmental movement repeated that they had nothing to do with what happened.