A survey by the Puerto Rico Health Department revealed that the cancer rate in Vieques is 27% higher than mainland Puerto Rico. In a 2001 federal lawsuit, Vieques' environmental groups and residents accused the Navy of causing "more damage than any other single actor in the history of Puerto Rico". The prosecutors stated that the Navy's activities contaminated much of the eastern portion of the island with a wide range of toxic substances. As cited by Franciscans International, according to the Navy's figures, throughout the course of six decades about 5 million pounds (2,000 t) of ordnance was dropped on Vieques every year. Ordnance included toxic compounds and elements such as arsenic, lead, mercury, cadmium, depleted uranium and napalm, and tons of a fiberglass-like substance. Most of these toxins are persistent and may bioaccumulate.