Chemicals Cleared in Pennsylvania Cancer Cluster

Published January 1, 2008

Scientists have cast doubt on high-profile accusations that industrial chemicals are causing an elevated number of cases of a rare disease, known as polycythemia vera (PV), in eastern Pennsylvania.

After lengthy and detailed study of environmental factors, scientists have found no link between environmental chemicals and the condition. The pocket of higher-than-normal PV cases in Schuylkill, Luzerne, and Carbon counties appears to be nothing more than a random statistical aberration.

PV is the overproduction of red blood cells, causing unusually thick blood. People with PV can live a normal life if they undergo blood removal and replacement when their blood gets too thick. The disease is not fatally invasive.

Chemicals Blamed

When it became apparent there were more than the usual number of PV cases in the three Pennsylvania counties, environmental activists were quick to assert industrial chemicals must be to blame.

Area residents suspected a chemical waste dump in Schuylkill County that was closed in 1979 and cleaned up through the Environmental Protection Agency’s Superfund program shortly thereafter. The Wilkes-Barre Times Leader suggested five coal-fired electric plants in the area might also be a factor.

The Wilkes-Barre and Philadelphia press sensationalized the ongoing investigation by state and federal officials. News reports included interviews with angry local citizens blaming their asthma and other illnesses on the suspect waste site.

The Pennsylvania State Health Director, Dr. Calvin Johnson, promised to keep an eye on things, and deputy state director Michael Huff said, “The department has committed to monitor the cases and see what might be causing this disease.”

Scientists Find No Link

Against this backdrop of fear, the federal Agency for Toxic Substances and Disease Registry (ATSDR) reported on October 24 investigators could find no pattern of exposure and disease that would implicate environmental chemicals. According to ATSDR, the individuals diagnosed with PV did not share common exposures that would raise concern about their cases being related.

Although fear had spread because PV appeared to be more prevalent than normal in a cluster of communities, scientists and statisticians know such random clusters happen.

“The risk of some factor in the environment causing this disease remains dubious at best,” said Dr. Gilbert Ross, medical director of the American Council on Science and Health.

“There is some expected variation in the rate of cancer across regions, just as with any other disease,” Ross added. “Some areas are hit harder, some less so–by chance. One-half of all counties will have a higher-than-average rate of whatever is being studied, while one-half will have a lower rate: [That’s] basic math.”

John Dale Dunn, M.D., J.D. ([email protected]) teaches emergency medicine at Carl R. Darnall Army Medical Center, Fort Hood, Texas. He is a science and policy advisor to the American Council on Science and Health.