ALLENTOWN — A federal researcher said Thursday he has not ruled out an environmental link to an elevated number of cases of a rare blood cancer in northeastern Pennsylvania, but that finding a cause is "somewhat of a fishing expedition."

The government reported Wednesday night that it confirmed a higher-than-expected incidence of polycythemia vera, or PCV, in Schuylkill and Luzerne counties but that its yearlong study found no link to something in the environment.

"We did not find any environmental links to the PV cases we interviewed," Vince Seaman, the lead researcher, said Thursday in an e-mail to reporters and an environmental activist. "That doesn't mean that there weren't any — we just didn't see anything with the information we collected."

Seaman, who is currently working on an assignment overseas, was not present Wednesday night at a heated community meeting in Hazleton at which the U.S. Agency for Toxic Substances and Disease Registry presented its findings.

The agency became involved after residents expressed concern about polycythemia (pah-lee-sy-THEE'-mee-ah) vera, a cancer that results in the overproduction of red blood cells and can lead to heart attack or stroke. Local activists have raised suspicions about a former toxic waste dump in northern Schuylkill County; the practice of filling abandoned strip mines with coal ash; and power plants fueled by waste coal — of which there are five in Schuylkill County.

Many of the patients diagnosed with PCV live near these sites, activists say.

Seaman said Thursday his findings suggest an "external factor" is at play. But he noted that until researchers discover the cause of PCV, "there is no specific place to start looking — it could be anything. ... It is still somewhat of a fishing expedition until we have a scientifically validated cause."