A federal grand jury investigation has been launched into the West Virginia chemical spill that left 300,000 people unable to use their water supply , CNN learned Tuesday . Sources familiar with the grand jury 's activities tell CNN that subpoenas have been issued requiring testimony for what one federal official confirms is a criminal investigation . Meanwhile , an independent water test conducted at CNN 's request has found trace levels of the chemical 4-methylcyclohexane methanol , or MCHM , remain in both untreated river water and tap water from two homes in Charleston . The results by TestAmerica found the chemical is within the safe level of 1 part per million set by the Centers for Disease Control and Prevention ; whether that level is safe is disputed . The test result detected MCHM in the river at .42 parts per billion ; residence # 1 at 1.5 parts per billion ; and residence # 2 at 1.6 parts per billion . The amounts in the residences are more than double that found in the river , but still considered a `` trace '' amount and within safe limits as set by the CDC . According to a source familiar with the probe , the grand jury investigation has been under way since just after the spill at the Freedom Industries chemical storage facility on the Elk River in Charleston . The spill came to light in early January . On January 9 , more than 7,000 gallons of 4-methylcyclohexane methanol leaked into Charleston 's water supply from a Freedom Industries storage tank . The result was a do-not-use order that left about 300,000 people in the area unable to drink or bathe in their water , some for more than a week . Freedom Industries later told regulators that in addition to the methanol compound that escaped from a ruptured tank , a second chemical -- a mix of polyglycol ethers , known as PPH -- was part of the leak . PPH is not believed to pose any new health hazard for the people of Charleston , the CDC said . But the state environmental agency said failing to accurately report the makeup of the leak is a violation of state law . The CDC said little is known about the health hazards of PPH , but it appears to be less toxic than MCHM and made up about 5 % of the total volume of the leaking tank . `` Given the small percentage of PPH in the tank and information suggesting similar water solubility as MCHM , it is likely that any amount of PPH currently in the water system would be extremely low , '' it said . `` However , the water system has not been tested for this material . '' Elizabeth Scharman , West Virginia 's poison control director , told CNN last month that MCHM had not been widely studied . `` We do n't know the safety info , how quickly it goes into air , its boiling point , '' Scharman said . The chemical is used to wash coal before it goes to market to reduce ash . Exposure to it can cause vomiting , dizziness , headaches , diarrhea and irritated skin , among other symptoms , the American Association of Poison Control Centers and CNN 's previous reporting shows . Another chemical leaked from West Virginia plant , company says . New health hazard , same story ?
Tests find trace levels of contaminant remain in West Virginia water . Federal grand jury investigates chemical spill . The January 9 leak prompted a do-not-use order for up to 300,000 people . Comment: