Children who live close to fracking sites in Pennsylvania have a higher risk for the most common form of childhood cancer, a new study finds
Researchers at the Yale School of Public Health used the Pennsylvania Cancer Registry, along with state data on unconventional oil and gas drill sites, to determine that children born within two kilometers, or 1.24 miles, of an active well site were two to three times more likely to be diagnosed with acute lymphoblastic leukemia (ALL) between the ages of 2 and 7.
The study was published Wednesday in the journal Environmental Health Perspectives. It looked at 405 children diagnosed with ALL between 2009 and 2017, and included 2,080 controls matched by birth year.
“The magnitude of the elevated risk that we observed was fairly striking,” said Dr. Cassandra Clark, a post-doctoral fellow at the Yale School of Public Health and co-author of the report. “After accounting for a variety of socioeconomic, demographic and biological factors that could potentially be underlying this association, it was consistent.”
Acute lymphoblastic leukemia is one of the most common childhood cancers, which is why the researchers chose to look at it. Additionally, a known cause is benzene, a chemical released by oil and gas drilling activities into both air and water. The five-year survival rate in children with ALL is high, at 90 percent.
Unconventional gas development is also referred to as fracking, which is a part of the overall process that injects water with chemicals at high pressure into shale rock formations deep underground to release oil and gas. Water that returns to the surface often includes those chemical additives, along with long-buried naturally occurring toxins and radiological material.
More than 10,000 unconventional natural gas wells have been drilled and fracked in Pennsylvania between 2002 and 2017. The Department of Environmental Protection has reported more than 1,000 spills in that period, along with fielding about 4,000 residential well water complaints between 2005 and 2014. Many who live in rural areas rely on private well water, about one-third of which are within two kilometers of a wellhead.
One unique aspect of the Yale research includes tracing potential drinking water exposure.
“It really is a superb study,” said Dr. Bernard Goldstein, former dean of the University of Pittsburgh School of Public Health and an expert in environmental causes of childhood leukemia. Goldstein is not associated with this study. He has conducted prior research into exposures due to oil and gas wastewater in Pennsylvania. “It looks at a potential problem in ways that include new exposure metrics, which are really needed.”
Goldstein says that though the factors that contribute to childhood leukemia are complex and still unclear, benzene is the one known link.
The interdisciplinary team of researchers included experts on leukemia and environmental science, as well as hydrogeologists. In addition to the location of well sites, researchers mapped individual watersheds and determined the flow of water from well heads to the children’s homes. They did not survey the families to determine individual sources of drinking water. Still, they say the research shows that a child living within 1.2 miles of a well site, which is within their watershed, could be at a higher risk of exposure through drinking water.
Previous research has shown an association between fracking activities and health impacts, but determining the path to exposure is more difficult.
“I think we have about 50 epidemiological health studies demonstrating increased adverse health outcomes in communities that live near unconventional oil and gas sites,” said Dr. Nicole Deziel, a co-author of the study and associate professor at the Yale School of Public Health in the Department of Environmental Health Sciences. “I think it would be very important to understand which exposures or hazards might be driving these associations.”
Deziel says she wants the study to impact public policy, including regulations on residential setbacks from wellheads and the density of drilling sites. Pennsylvania requires a 500-foot setback from schools and homes. Deziel says it should be 1,000 meters, especially since her findings show greater impacts for those children exposed in utero.
“We saw some stronger associations when we restricted that time window to children who had an exposure in utero,” she said, “suggesting that that may be a sensitive time window, which is also consistent with some other studies of other environmental exposures.”
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