Experts[who?] estimate that Paraguay lost 0.5 percent of its forest cover each year between 1990 and 2000. Paraguay also has a growing pollution problem. Many of the country’s rivers suffer from toxic dumping. Tanneries are particularly harmful, releasing mercury and chromium into rivers and streams. Runoff from toxic chemicals used by farmers also seeps into Paraguay’s waters. In the Chaco, the salination of already arid land makes farming even more difficult. Furthermore, poachers have almost free rein in Paraguay, and continue to foster the illegal trade in armadillo, deer and crocodile skins.