Jan Brown, of Englewood, Colo., holds up a sign during a rally to show support for Proposition 112, which would increase drilling setbacks, that will appear on the November election ballot Saturday, Oct. 13, 2018, outside the state Capitol in Denver.

David Zalubowski/AP Photo

The contentious ballot measure Proposition 112 would increase setbacks statewide from 500 feet to 2,500 feet between new oil and gas wells and homes, schools and waterways.

But that nearly-half mile distance isn't a magic number. And while research does connect proximity to oil and gas sites with health issues, there's still more work to be done.

Those are some of the findings in a new report from the Colorado Health Institute. The group is nonprofit and nonpartisan, and did not take a position on Proposition 112 in its analysis.

The Colorado Health Institute analyzed reports from the Colorado Department of Public Health and Environment. The department created the Oil and Gas Health Information and Response Program in September 2015 to respond to the public's health concerns related to oil and gas activities. 

Hundreds of people have reported health problems to the program over the past three years. The 604 health concerns reporter ranged from the short-term—headaches, dizziness, and eye, lung, throat and nose irritation—to long-term anxiety and sleep disturbance from vibrations and noise related to drilling.

Most reports come from three Front Range counties: Weld, Boulder and Adams. Weld County, which has the most oil and gas wells in Colorado. It accounts for nearly two-thirds of people making health complaints.

Two peer-reviewed studies, on which the ballot proposal is based, do show that there are positive correlations between living close to oil and gas sites and health issues. However, the Colorado Health Institute identified limitations in that research:  a small number of cases were studied in one report, and in another, the factors measured were distance and density of wells, not their emissions.

"There has been research on this, but it's a new subject," said Karam Ahmad, a Colorado Health Institute policy analyst who co-wrote the report. "There's new technology in oil and gas, oil and gas has developed in areas where people live and people play. So the research is still building. There are still more opportunities for research."

Proposition 112 is a complicated issue, Ahmad said, and he understands how its potential impact on health and on jobs makes the measure controversial.

"Regardless of what happens in this election, people are still reporting health impacts in Colorado," Ahmad said. "These are real impacts that people are reporting. At the same rate, people have jobs. It comes down to what people value."