A new poll by the Paul Simon Public Policy Institute at Southern Illinois University Carbondale finds voters are divided over whether hydraulic fracturing, or fracking, should be encouraged for its economic benefits or discouraged because of its environmental impact.  There were 40.7 percent who said it should be encouraged and 39.7 percent who said it should be discouraged.  About 20 percent had no opinion.  The survey of 403 registered voters in the 18 southernmost Illinois counties was taken September 20^th through October 2^nd.  The poll has a margin of error of 4.9 percent.  The survey found a plurality of respondents feel hydraulic fracturing is a somewhat safe natural gas and oil extraction technique.  Nearly one-third of respondents saw hydraulic fracturing as not very safe or not at all safe, while one in 10 felt the technique is very safe.  Hydraulic fracturing utilizes the high-pressure injection of water, sand, and chemicals into rock formations deep underground.