The battle over the controversial natural gas process known as "fracking" got a little hotter today after the Environmental Protection Agency announced it has subpoenaed energy giant Halliburton after the company refused to submit information for a congressionally mandated study..."[F]racking" has been the subject of intense debate...It's supported by businesses and landowners who tout its benefit to a struggling economy, and opposed by those who charge the process -- where...potentially toxic chemicals are injected into the earth -- contaminates wells and threatens public health...According to the EPA, eight of the companies----BJ Services, Complete Production Services, Key Energy Services, Patterson-UTI, RPC Inc., Schlumberger, Superior Well Services, and Weatherford---complied with the information request or made "unconditional commitments to provide all the information on an expeditious schedule". Only Halliburton failed to provide the EPA with the information it requested.