A pumpjack is used to lift
liquid from an oil well.
Photo by Eric Kounce
Living in an area of high-density oil and gas development may increase a young person’s risk of developing acute lymphoblastic leukemia (ALL), according to research published in PLOS ONE.
The study showed that children and young adults in Colorado who had been diagnosed with ALL were more likely than young people with non-hematologic cancers to live in areas of high-density oil and gas development.
However, there was no such association for young people with non-Hodgkin lymphoma (NHL).
“Over 378,000 Coloradans and millions of Americans currently live within a mile of at least one oil and gas well, and petroleum development continues to expand into residential areas,” said study author Lisa McKenzie, PhD, of the University of Colorado Anschutz Campus in Aurora.
“The findings from our registry-based, case-control study indicate that young Coloradans diagnosed with one type of childhood leukemia are more likely to live in the densest areas of oil and gas sites. More comprehensive research that can address our study’s limitations is needed to understand and explain these results.”
Dr McKenzie and her colleagues said they conducted this study because oil and gas development emits known hematological carcinogens, such as benzene, and increasingly occurs in residential areas.
The team wanted to determine whether living near areas of oil and gas development was associated with risk for hematologic cancers. So they analyzed data from the Colorado Central Cancer Registry and the Colorado Oil and Gas Information System.
The study included 743 subjects, ages 0 to 24, living in rural Colorado and diagnosed with cancer between 2001 and 2013. This included 87 ALL cases, 50 NHL cases, and 528 controls with non-hematologic cancers. (Other hematologic malignancies were not included in the analysis due to small numbers.)
Data analysis
The researchers used information from the Colorado Oil and Gas Information System to build a geocoded dataset with coordinates of all oil and gas wells in rural Colorado and determined dates for when each well was active.
Geocoded residential addresses of cancer patients at the time of diagnosis were linked to active well locations in the year of diagnosis and active well locations in each of the 10 years preceding the cancer diagnosis.
The researchers then took the inverse of each distance and summed the inverse distances to calculate inverse distance weighted (IDW) oil and gas well counts within a 16.1 km radius of each participant’s residence at cancer diagnosis for each of the 10 years prior to the date of diagnosis. (The IDW well count method gives greater weight to the wells nearer the home.)
The team used logistic regression to estimate associations for cancers across IDW well count tertiles. The first tertile had less than 4.9 wells per 1.6 km, the second had 4.9 to 33.6 wells per 1.6 km, and the third had more than 33.6 wells per 1.6 km.
Results
The researchers found an increase in the odds of living near oil and gas development at the time of ALL diagnosis, even after adjusting for age, race, gender, income, elevation, and year of cancer diagnosis.
ALL patients ages 0 to 24 were twice as likely as controls to live in the densest area of active oil and gas wells (highest IDW well count tertile).
ALL patients ages 5 to 24 were 4.6 times more likely than controls to live in areas included in the highest IDW well count tertile.
However, there was no significant association between ALL and proximity to oil and gas development in ALL patients ages 0 to 4. The adjusted odds ratio was 0.51 for the highest IDW well count tertile.
Likewise, there were no significant associations between density of oil and gas development and NHL. The adjusted odds ratio was 0.99 for the highest IDW well count tertile.
Limitations and next steps
The researchers said this study was limited by the low occurrence of ALL and NHL in rural Colorado, lack of specific age at cancer diagnosis, and the fact that all study participants had been diagnosed with cancer.
In addition, the study was limited by the lack of information on specific activities at the well sites, place of residence before cancer diagnosis, other sources of pollution around the residence, and individual characteristics such as common infections and family history of cancer.
The team said future research should incorporate information on oil and gas development activities and production levels, as well as levels of specific pollutants of interest such as benzene, near homes, schools, and day care centers.
They recommended that such research consider specific ages and residential histories, compare cases to controls without cancer, and address other potential confounders and and environmental stressors.
