A report by the Environmental Protection Agency (EPA) last month found that hydraulic fracturing for oil and gas can lead, and has led, to the contamination of drinking water. It was the first time the federal government had admitted such a link. But Gretchen Goldman, a lead analyst at the Center for Science and Democracy at the Union for Concerned Scientists, told the Guardian that the EPA's study - which is now open for comment - was nothing "more than a literature review" and called for the industry to be required to divulge greater data. Goldman says the EPA backed down from its initial promise to undertake prospective studies, which would have involved following a well site and testing its waters before, during and after fracking activities had begun. Such a study would have shed objective light on the fracking process and pushed scientific knowledge forward, she says. Even when companies were forced to share information through state regulations, they were still allowed to withhold ... the identity and mixture of chemicals that are injected into the ground through wells, together with water, at high intensity to fracture underground rocks and release oil or gas. In 2005 lobbying efforts by the oil and gas industry proved successful, with hydraulic fracturing activities exempted from certain sections of the Safe Drinking Water Act, including permit application.