The U.S. Environmental Protection Agency (EPA) has asked Ameren Corp. and subsidiaries to expand their investigation into PCB (polychlorinated biphenyl)-contaminated liquids found in natural gas distribution systems in Alton and East St. Louis, IL, the agency said last week.

Ameren, under federal and Illinois EPA oversight, recently inspected the gas supply equipment at Alton Middle School and 12 residences in East St. Louis. The gas equipment in the school did not contain PCBs. However, three liquid collection points outside the school were found to have liquids with PCBs and Ameren removed them. Low levels of PCBs were discovered in liquids in gas meters outside three residences in East St. Louis. Ameren replaced the meters and cleaned the soil beneath them, EPA said.

EPA directed Ameren to revise a draft inspection plan for buildings where the PCBs were previously found. EPA also specified procedures for sample collection, analysis and further investigation if warranted. The agency said it expects a response from Ameren "in the next few days."

In July EPA announced an investigation into PCB contamination of the Nicor Gas distribution system in Park Ridge, IL. Last week the agency said the company's inspection of 135 homes in Park Ridge showed that the problem of PCBs in gas meters is "probably not widespread."

PCBs were used historically in some gas distribution equipment, typically as a compressor lubricant or valve sealant. PCBs are mixtures of synthetic chemicals ranging from oily liquids to waxy solids. Because of evidence that PCBs persist in the environment and have harmful effects, domestic manufacture of commercial mixtures was stopped in 1977. Existing PCBs continue to be used. EPA says they are probably carcinogens. In rare cases, liquids in natural gas pipelines can migrate through meters, interrupting pressure or gas flow to appliances in homes. Pipeline liquids are typically methane, propane and butane but may also contain PCBs.

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