A pilot study of childhood leukemia patients living near Colorado oil and gas drilling sites recently led to an American Cancer Society (ACS) grant for Lisa McKenzie, CU Cancer Center Fellow, PhD, MPH.
For the pilot study, which was partially funded by the CU Cancer Center, McKenzie, a clinical assistant professor in the department of environmental and occupational health at the Colorado School of Public Health, used the Colorado Central Cancer Registry to compare diagnosed children. with acute lymphoid leukemia (ALL), a type of cancer of the blood, to children diagnosed with other types of cancer.
“What we found in this study is that children with ALL were four times more likely to live in the highest density of oil and gas areas than children diagnosed with another type of cancer,” says McKenzie .
The striking results of the pilot study led McKenzie to apply for funding from ACS to conduct a larger population-based case-control study. McKenzie funding for the four-year grant will begin July 1.
Map a potential link between acute lymphoid leukemia and oil and gas production
McKenzie chose to focus on leukemia because of its relationship with the chemical benzene. Benzene is a colorless, flammable liquid and a natural component of crude oil and gasoline, so it is emitted at varying levels from oil and gas sites. It is also a known carcinogen, most closely associated with acute myeloid leukemia (AML), which occurs mainly in adults.
Unlike AML, McKenzie says little is known about the environmental causes of ALL, the most common type of childhood leukemia. “Benzene hasn’t necessarily been involved in ALL, but that hasn’t been ruled out either,” she says. This study will examine whether there is a potential link between the two.
The new study will draw its control group from the Colorado birth registry and its case group from the Colorado Central Cancer Registry. The control group will exclude children who have been diagnosed with any type of cancer other than ALL. Similar to the pilot study, McKenzie hopes to determine whether children living near oil and gas sites – and therefore closer to areas where benzene emits – are more likely than other children to develop ALL.
“The reason we chose children is that the time between exposure and cancer onset (the latency period) is much shorter in children than in adults,” explains McKenzie. The primary age group for the study is children aged two to nine, although McKenzie is also considering an exploratory goal to examine infants aged zero to one.
The new study will have several advantages over the pilot study. In addition to drawing his control group from the birth register, he will also take into account not only a child’s proximity to an oil and gas site, but also the intensity of activity at these sites.
“Different things happen at oil and gas well sites at different times,” explains McKenzie. “Some of them are in production, some of them are what we call closed, which means they are not producing anything, and others are being actively drilled.” All of these can affect benzene emission levels.
The new study also gives researchers additional data benchmarks for each child. For all children, their date of birth and address at birth will be taken from the birth register. For the group of cases (children with ALL), their age at diagnosis and their address at diagnosis will come from the cancer registry. And for the control group, researchers will use a search engine to find each child’s address (based on information from the mother) and age at the time their corresponding case was diagnosed with ALL.
“It’s important when we think about environmental exposures, because there’s this mismatch between exposure to something in the environment and the expression of cancer,” McKenzie explains.
The second objective of the study is to explore another potential reason for the apparent increase in diagnoses of ALL in children near oil and gas sites: a social and epidemiological phenomenon called population mixing.
“When you have a large influx of people, like when there is a big boom in oil and gas development, it can introduce new pathogens that might cause some kind of abnormal immune response, especially in children with a bad system. more naive immune system, ”McKenzie explains.
Understand the risks and advance research techniques
McKenzie says this research is especially important in areas like Colorado where oil and gas production is important. Colorado was among the top five crude oil producing states in the country in 2020, according to the US Energy Information Administration.
“It is beneficial for us to understand what those risks might be, because it helps us decide what we can do to mitigate some of these risks,” she says.
For this reason, in addition to the expected academic manuscripts and peer-reviewed publications, McKenzie expects that an additional outcome of this research may be the presentation of his team’s findings to community members and interested decision makers. .
She also hopes the project will help her and future researchers improve the way they estimate environmental exposures in retrospective studies.
“For a retrospective study, you can’t go back and take measurements on people,” she says. “And a lot of information on air pollution is just not available – it is not being collected – so you have to start thinking about different ways of understanding what is going on.”
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