Natural-gas producers must do more to reduce environmental harm from hydraulic fracturing and disclose U.S. drilling risks, according to groups representing investors with more than $130 billion in assets. Companies such as Exxon Mobil Corp. (XOM) should identify the chemicals used and consume less water in fracturing to free gas trapped in rock, according to a report released today from the Investor Environmental Health Network and the Interfaith Center on Corporate Responsibility. [also refers to Encana, Cabot Oil & Gas, Chesapeake Energy]