The association between dramatically elevated rates of polycythemia vera in several Pennsylvania counties and the proximity of waste-fuel-fired power plants appears to be real and can't be explained by those counties' aged populations.
That's the conclusion of an analysis by Dr. Samuel Lesko, medical director of the Northeast Regional Cancer Institute
in Scranton, Pa. It comes as scientists with the U.S. Agency for Toxic Substances and Disease Registry are in the Hometown area
to study its unusually high incidence of PV, a rare blood malignancy that scientific studies have linked to radiation, solvent and benzene exposure.
Lesko's finding came as he scrutinized research I conducted earlier this year
using PV data
obtained from the state cancer registry for 2001 to 2003. I excluded from consideration those counties with populations under 100,000, since one or two cases there would drastically skew the incidence rate. Among the 33 Pennsylvania counties I did consider, there were four where PV rates were at least double the state's, which is already nine to 23 times the nation's. Those counties were Blair, Cambria, Luzerne and Schuylkill.
In looking for common environmental factors among counties with an elevated PV incidence, I initially hypothesized that those with the highest rates would be downwind of Three Mile Island or the state's other nuclear power plants, all potential sources of ionizing radiation. As it turned out, I found no relationship between PV and nukes.
However, I did find an association between PV and the presence of waste-fuel-fired power plants, which are major sources of toxic pollutants
including lead, mercury and polycyclic aromatic hydrocarbons, combustion compounds that are related to benzene. Burning coal -- especially waste coal -- also produces radiation.
Of the 18 waste-fuel-burning power plants currently operating in the United States, 14 are in Pennsylvania, and five are in Schuylkill County, which has more than any other county in the nation, according to the Energy Justice Network
. Schuylkill County's Ben Titus Road community -- where the Army for a Clean Environment
has counted as many as eight cases of PV -- is adjacent to Northeastern Power Co., which burns anthracite coal waste or "culm" as its primary fuel and diesel or fuel oil as a secondary fuel, according to EJN.
NEPCO sits on the border of Luzerne County, which is also home to another waste-coal-burning plant -- the Hunlock Power Station west of Nanticoke. That facility burns anthracite coal as its primary fuel and culm as a secondary fuel. In the south-central part of the state, Cambria County has three waste-coal facilities: Cambria Cogen and Ebensburg Power, gob-burning plants in Ebensburg, and the Colver Power Project in Colver, which also burns gob. The Ebensburg facilities are located about 10 miles west of the Blair County border.
Many of these plants, including NEPCO, dump the toxic ash that remains after incineration in nearby mine pits, threatening local groundwater supplies with leaching poisons. In addition, at least one study
has documented elevated radiation levels in a waste coal ash landfill.
As part of my research, I created a map
showing the 10 waste-fuel-fired power plants located in the 33 populous Pennsylvania counties. I thus discovered that nine of the plants were in -- or, in the case of Blair County, on the border of -- the counties with the most dramatically elevated PV rates. That suggested to me that the pollution coming from those plants was a factor.
After I published my analysis, Lesko e-mailed me to point out that it suffered from a major shortcoming: I failed to account for age. That's important, because the risk of PV increases dramatically with age, and the four counties where I found the highest PV rates are also among those with the oldest populations. As Lesko wrote at the time:
So, age cannot be ruled out as a possible explanation for the high rates in these counties. If a similar pattern was observed for a map showing age-adjusted incidence rates, it would make a more compelling case that something is going on.
Unfortunately, PADOH doesn't make it easy to calculate age-adjusted PV incidence rates. When I requested PADOH's numbers on the disease, staff informed me that they would provide for free only the number of cases by county. They would not give me the data broken out by age category, which is necessary to conduct an age-adjusted analysis, without imposing a hefty fee that my shoestring operation couldn't afford.
Fortunately, Lesko came to the rescue and obtained the PV data for each county broken down by age category. He then had me collect the Census Bureau's 2000 population data for the four counties where I found the most dramatically elevated rates, which he used to age-adjust the rate for those counties. This is the text of the e-mail I got from him yesterday reporting his findings:
Thanks for forwarding the age-specific populations for the four counties of most interest (Blair, Cambria, Luzerne and Schuylkill). I used these data to compute age-standardized incidence figures (Standardized Incidence Ratios) comparing the observed incidence in these counties to the corresponding incidence in all of PA combined. The SIRs for each county remains elevated, although the disparity is not as large as with the unadjusted rates. The SIR and 95% Confidence Interval for these counties are as follows:
These ratios tend to be a bit smaller than the unadjusted ones used in the map you circulated in September. Except for Luzerne, the incidence in each of these counties is not more than twice the PA incidence, but they are still elevated (and close to double the PA rate).
This analysis tells us that the high incidence is not due to age alone. The 95% confidence intervals gives us some idea of the precision of these figures.
So it does appear that pollution from waste-fuel-burning power plants may be a possible culprit behind elevated PV rates. The question is, what will regulatory authorities and elected leaders do now that they know these facilities may be hurting the public's health?
Labels: polycythemia vera