A new study found that children diagnosed with a form of leukemia between 2002 to 2019, during Colorado’s hydraulic fracturing boom, were more likely to live near oil and gas well sites than children without cancer.
Children between 2-9 years old who lived within 3.1 miles of wells with high activity faced the greatest risk of developing acute lymphocytic leukemia, compared to those living farther away from significant operations. Overall, Colorado children between 2-9 years with the cancer were more likely to live within 8.1 miles of an oil or gas site, compared to children without the disease. The research was published in Cancer Epidemiology, Biomarkers & Prevention.
“Children all the way out to 13 kilometers [8.1 miles] – if they have a lot of oil and gas development around them, are at an increased risk for childhood leukemia, with children within 5 kilometers [3.1 miles] bearing the greatest risk,” said Lisa McKenzie, an associate professor at the Colorado School of Public Health and lead author of the peer-reviewed study, which was funded by the American Cancer Society.
Leukemia is a form of blood cancer that makes it harder for children to fight off common infections. Acute lymphocytic leukemia, one of the most common forms of pediatric cancer, affects the body’s lymphocytes, or white blood cells that destroy foreign bacteria or viruses.
Certain oil and gas work can emit benzene, an industrial chemical that some studies have linked to higher rates of leukemia. Oil and gas operations can also lead to an increase in traffic and heavy machinery, which can emit plumes of air pollution.
The study did not identify the cause of the increase in leukemia risk, or how exposure to certain chemicals contributes to cancer development. McKenzie said those topics deserve further research. There might also be other "confounding" factors that the study did not fully account for, which could complicate the relationship between oil and gas drilling and cancer risk.
“We don’t have the data to actually say for example, how much benzene each one of these children were exposed to,” McKenzie said. “We’re just looking at the overall density of oil and gas development, so we don’t know specifically what it is that might be causing childhood leukemia.”
The Colorado Oil and Gas Association, an industry advocacy group, strongly objected to the study's findings and called McKenzie’s previous work “misleading.” In 2017, McKenzie published a smaller pilot study that found that children and young adults in rural Colorado diagnosed with acute lymphocytic leukemia were more likely to live near active oil and gas operations than those with other types of cancers. The study recommended more comprehensive research.
“Her previous work contained such significant flaws in the methodology that the Colorado Department of Public Health & Environment (CDPHE) publicly highlighted these ‘significant limitations’,” said Gabby Schaefer, COGA’s director of communications and marketing, in an email.
At the time, Dr. Larry Wolk, then head of the Colorado Department of Public Health and Environment, said in a statement that the study had limitations – which the findings acknowledge – and did not establish a definitive link between oil and gas operations and childhood leukemia.
Schaefer, COGA’s spokesperson, said in an email that the group shared similar concerns about the latest research, adding that it shows a lower leukemia risk for children than the 2017 findings.
In her findings, McKenzie writes that the difference may be because the newer study design is more rigorous and adjusts for more environmental factors. This study builds on the 2017 pilot by expanding the sample size to all children in Colorado, examining the intensity of oil and gas activity during each month before a child was diagnosed with cancer, and considering wells up to 10 miles away from homes.
A spokesperson for CDPHE, which helped with the current study, said the agency hadn’t reviewed the findings but that it welcomed research on the health impacts of pollutants.
Colorado regulators do not allow oil and gas drilling less than 2,000 feet from homes and schools, though certain exceptions mean drilling can take place as close as 500 feet away. McKenzie said current “setback” requirements might be too weak to ward off health risks for Coloradans who live close to intense oil and gas activity.
“It is likely that current setback regulations are not sufficient to protect public health, and policymakers should reconsider existing standards not just in Colorado, but also in other states where oil and natural gas activity is prevalent,” McKenzie said in a release.
The state’s Energy and Carbon Management Commission, which regulates oil and gas activity, has not yet reviewed the study and did not comment on the efficacy of existing setback regulations.
Intensity and proximity to oil and gas could make a difference
This study – known as a “case-control” study – compares children who have leukemia to children who don’t. CDPHE staff compiled a list of every live birth in Colorado from 1992 to 2019. They then whittled that down to only include children aged 2-9 years old with no previous cancer history, and who were diagnosed with leukemia between 2002 - 2019, which eventually yielded 451 cases. Researchers designed the study period to coincide with a surge in “unconventional” techniques like fracking, which spurred a dramatic rise in oil and gas development in Colorado.
Researchers then compared those cases to “controls” – or children who did not have any form of cancer before they were 10, and who were born in the same window. They mapped where those cases and controls lived compared to thousands of oil and gas wells, as well as other polluting sites, like highways, and gave more weight to sites closer to a child’s home.
“It’s not that every child living near oil and gas is going to get leukemia. It’s just that they are at a higher risk, remembering that child leukemia is a rare disease,” McKenzie said.
The study contributes to a small body of evidence from McKenzie and other researchers exploring the relationship between oil and gas operations and diseases. But limitations remain, especially in understanding how cancers develop.
“We suspect it has something to do with benzene emissions, but we don’t know that for sure,” McKenzie said. “And we don’t know everything that is emitted from those sites. We only know what we’ve measured.”
A 2019 CDPHE study found that Coloradans could face headaches, nausea and nosebleeds from close exposure to chemicals found in oil and gas operations. In 2020, Colorado’s oil and gas regulators cited the study to set stricter setback rules, part of a broader push, mandated by lawmakers, to better regulate the public health impacts of fossil fuel development.
McKenzie said regulators should consider changing setback rules to account for more than just the distance of one well or pad from a home.
“They don't account for all the other oil and gas development that might be going on,” she said. “And they also don't account for all the other sources of air pollution that could be around.”
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