Two-fifths of Chevron Corp (CVX.N) shareholders support greater disclosure about the risks of hydraulic fracturing following the company's big move into the "fracking" business through an acquisition last year...Fracking is used to extract natural gas or oil from shale rock by blasting in a mix of water, chemicals and sand. The practice has created serious concerns about water contamination... Chevron...became heavily involved in the huge Marcellus shale region centered on Pennsylvania through its purchase last year of Atlas Energy and a recent acreage deal with Chief Oil & Gas...A Chevron spokesman said fracking is regulated well enough at the state level to not need federal oversight, and the company believes fracking can be done safely...Chevron also supports the publication of chemicals used in the process, and the company will make its first disclosure online by the end of June, he added.