A federal agency admits there's a 20-mile stretch in Pennsylvania where residents have an elevated risk of contracting a rare blood cancer.

Officials say people living between Hazleton and Tamaqua are four times as likely to suffer from the rare disease, known as PV, as anyone in the outlying area.

The area 80 miles northwest of Philadelphia is home to several Superfund toxic cleanup sites and a power plant fired by waste coal, though the government report stresses not enough data exists to trace the cancer cluster to a specific source.

Some residents blame a center where paint sludge, waste oils, and other carcinogens were recycled 30 years ago, as well as the power plant.

It's the only cluster of PV recorded in the U.S., though officials say it's likely there are others.