Colorado panel looks into chronic health risks near oil and gas production

A panel of public health, toxicology and energy experts reviewed three Colorado studies on the health effects of oil and gas development, ultimately finding that there are short-term exposure risks near drilling sites, but long-term risks are well managed by engineering practices.

The Colorado Energy & Carbon Management Commission (ECMC) — the state regulatory agency that oversees energy development — pulled together a panel of 15 experts to review three separate studies on the health effects of oil and gas development, including links to acute lymphoblastic leukemia (ALL) and the effectiveness of current residential setbacks from well pads, which are the base of operations for a oil or gas drilling.

Ultimately, the group found that long-term health risks near oil and gas sites are rare under current best practices and state regulations, but acute risks during the drilling phases are real and understudied.

“There are health risks living in close proximity to fracking wells,” Jacob Fox, a physician in pulmonary and critical care medicine and member of the panel, said during webinar on July 21. “What the state does is they try to balance those health risks and try to identify a threshold that’s safe for communities to live at. I think we don’t know exactly what that is. These studies help us better understand, but there’s still more work we need to do.”

Cumulative health risks

The first study looked at areas in Broomfield with overlapping exposure from oil and gas, traffic and ozone levels that fail to meet National Ambient Air Quality Standards. Overall, the study — conducted by the Environmental Defense Fund, Colorado State University and Colorado School of Public Health between 2018 and 2023 — examined how these different factors may come together to create negative health effects, both long-term and short-term.

Long-term health effects, like cancer, were found to be close to background levels, according to researchers. But short-term issues, like spikes in respiratory symptoms in people with asthma, may be increased during drilling due to a combination of bad ozone levels and volatile organic compounds (VOC), or carbon-containing chemicals that quickly evaporate into the air at room temperature.

“Greater protection to public health could be afforded by establishing policies that require drilling and well completions to be conducted outside the summer ozone season,” the study says.

After review, the panel found acute effects near well pads during drilling and completions; at one community site, effects were documented about 1,000 feet away during production. Colorado state law requires that pads be 2,000 feet from residences, hospitals and schools, however. A person’s health background made significant differences in direct effects, the study added.

Researchers also found that estimated lifetime cancer risk from VOC exposure exceeded Environmental Protection Agency benchmarks at every site sampled, including a site around three miles from any Broomfield well pad. Since the far-away site showed the same estimates as ones near active drilling, the panel noted that the finding may reflect urban and traffic-related pollution rather than oil and gas activity, specifically. Researchers also cautioned that the cancer estimates assume constant, peak-level VOC exposure sustained for 30 years, a scenario that likely overstates real-world risk with fluctuating levels and relocating individuals.

It’s important to note the difference between causation and correlation, according to Kristy Richardson, a state toxicologist. It would be hasty to say VOC and high ozone levels together increase acute effects, because one could be causing it on its own, she said.

Pollution near unconventional development

A second study conducted by CSU looked at hazardous air pollutants at development pads in Colorado’s Denver-Julesburg (DJ) Basin from October 2022 to August 2024. These four pads used electric drilling rigs rather than diesel rigs, theoretically lowering emissions during the drilling phase.

The study didn’t find any exceedances of chronic health guidelines at monitoring stations placed 1,000 to 1,500 feet from the pads, closer than the state’s required 2,000-foot setback. Generally, acute risks also dropped below all guideline values by around 2,000 feet. The panel noted that the use of electric rigs was an important caveat, since results might look different at sites still using traditional diesel equipment.

One interesting aspect: the Tracking Community Exposures and Releases (TRACER) model, a software tool created for the study that was designed to simulate VOC emissions. The panel said the tool only works 1,000 to 1,500 feet from a pad, though, and should not be used for regulatory settings until it has further review.

Finally, the study found that closed-loop, tankless systems — newer production facilities that reduce vapors and flaring and limit emissions — cut both VOC and benzene emissions during flowback by more than 95% versus other completion methods. But the panel said even more could be done to improve on that number, like reducing plumes released during the emptying of sand canisters.

Leukemia risks

A third study, and the one most questioned by audience members, looked into correlations between childhood acute lymphoblastic leukemia (ALL) and distance to oil and gas development. The Colorado School of Public Health, Boise State University and the University of Southern California partnered for the study, which reviewed children who were born between 1992 and 2019, and diagnosed with ALL between ages two and nine.

According to the study, Colorado children living within 13 kilometers (around eight miles) of oil and gas well sites had an increased risk for ALL, with children within 5 kilometers “bearing the greatest risk.”

“Current setbacks between O&G well sites and residences may not be sufficient to protect the health of these children,” the study said.

Panelists cautioned the public to remember the difference between causation and correlation, with other similar studies not finding a direct causation between direct exposure and ALL. “The problem we always have in public health science is that your risk of getting leukemia from exposure to benzene is related to all of your exposure to benzene,” Richard said. “I never have a perfect record of that.”

“It’s the most common cancer of childhood,” Fox added, noting that while it is something worth looking into more, a study cannot say a distance will increase the risk of cancer in a specific individual.