A new study from University of Colorado researchers finds a possible link between a specific kind of childhood cancer and nearby oil and gas activity, but the state Health Department and others are challenging the conclusion.
The study is the latest attempt to answer an increasingly important question in Colorado: Does living near an oil and gas well impact your health? CU School of Public Health professor Lisa McKenzie and five colleagues examined data from a state registry of cancer cases. They concluded that people ages 5-24 who were diagnosed with acute lymphocytic leukemia were more likely to live in areas with a high concentration of oil and gas activity.
"It's important that more studies be conducted to understand why," McKenzie said.
But Dr. Larry Wolk, the executive director of the Colorado Department of Public Health and Environment, said the study's conclusion isn't convincingly reached. He cited limitations in the study's design and data analysis and said the possible link between childhood cancer and high-concentration oil and gas development hinges on just 16 cases.
"I don't think the study supports the conclusion that they made," he said.
In a 2014, she and colleagues published a study finding a possible connection between congenital heart defects and proximity to an oil and gas well. Wolk raised similar criticisms of that study, saying that readers "could easily be misled to become overly concerned."
Oil and gas advocates also have criticized McKenzie's research. The Colorado Oil and Gas Association put out a statement Wednesday saying that, while it would review McKenzie's data, "researchers shouldn't be in the game of scaring people." Of the new study, Tracee Bentley, the executive director of the Colorado Petroleum Council, said: "This is more of the same and an attempt to undermine energy development and jobs in Colorado."
McKenzie denied she is trying to push an agenda, while acknowledging that the study has limitations that mean it falls short of proving a link. She said she provided CDPHE officials with a copy of her study before publication and tried to address their concerns in the final manuscript.
"We did the best study we could with the data that the Colorado Health Department was able to provide to us," she said.
For the study, McKenzie and colleagues looked at 743 cases of cancer reported between 2001 and 2013 in children and young adults living in rural areas of Colorado. They compared those numbers to data on active oil and gas wells throughout the state.
The researchers specifically looked at cases of acute lymphocytic leukemia - a cancer that starts in bone marrow - and at cases of non-Hodgkin lymphoma. They then weighed the number of those cases reported in high-density and low-density oil and gas areas against the numbers of other kinds of cancer reported in those areas.
While the researchers found no link between non-Hodgkin lymphoma and oil and gas development, they did find a statistically significant correlation between oil and gas and acute lymphocytic leukemia in people ages 5-24. McKenzie said pollutants associated with oil and gas activity - such as benzene - are known to potentially cause cancer.
"That's why we did the study," she said. "So, I don't think we were surprised by this result."
Wolk, though, said the study didn't adequately account for other potential causes of cancer and said it also didn't look at neighborhood turnover or length of exposure to the pollutants. Previous CDPHE studies have found benzene levels in neighborhoods near oil and gas developments within the accepted ranges, he said. Wolk said the new research ultimately found 16 cases of acute lymphocytic leukemia in areas of high-density oil and gas development during the study period.
Still, he said, the issue is important to explore further. He said CDPHE hopes to publish a summary of research on the health impacts of oil and gas development in the coming weeks.