People who live near oil and gas developments could be at a greater risk for cancer and other health problems because of hazardous air pollutants emitted by oil and gas sites, according to a study published Monday by the Colorado School of Public Health at the University of Colorado Anschutz Medical Campus.

The Colorado Oil and Gas Conservation Commission mandates new oil and gas wells be set back least 500 feet from a residence and 1,000 feet from high-occupancy buildings like schools and hospitals. But the study found that people who live 500 feet from an oil and gas site have a lifetime cancer risk eight times higher than the acceptable limit set by the Environmental Protection Agency. The study also found that risks of respiratory, neurological, hematological and developmental health issues are greater in people who live near oil and gas sites.

“Our results suggest that Colorado’s current regulations that specify a 500-foot distance between a newly drilled oil and gas well and an existing home may not protect people from exposures to hazardous air pollutants that could impact their health,” said Colorado School of Public Health Assistant Research Professor Lisa McKenzie, the study’s author, in a news release.

The study focused the emission of non-methane hydrocarbons, a group of compounds that includes harmful pollutants such as benzene, from oil and gas sites along the Colorado Front Range. Benzene has been proven to cause multiple forms of leukemia, cardiovascular disease and bone marrow disease. The study found average benzene concentrations were 41 times higher within 500 feet of a well than they were a mile away. Furthermore, according to the study, benzene concentrations are twice as high at night, when more people are likely to be home, because the emitted pollutants don’t disperse as quickly in the colder night air.

The study also corroborated existing data from Colorado that showed children living near oil and gas development have higher risks of childhood cancers and congenital heart defects, as well as data from studies in Pennsylvania and Texas that found a connection between proximity to oil and gas development and miscarried pregnancies, low birth weight, premature birth, asthma, fatigue and migraines.

Dr. Larry Wolk, executive director of the Colorado Department of Public Health and Environment, released a statement Monday saying the new study showed increase risk only at distances within 500 feet. When results taken from that close are removed, he said, remaining results show no increased levels of benzene or other chemicals.

While Wolk claims more testing is needed, he also said this new study only reinforces the state’s 500-foot rule.

“This report underscores the potential public health importance of the 500-foot setback and the need to collect more comprehensive air quality data in communities in close proximity to oil and gas operations,” he said in the report.

He said he expects the department to release a report based on what it calls more comprehensive air-quality data completed this summer.

Officials from the COGCC and the Colorado Department of Natural Resources declined to comment on the study’s results. Officials from the Colorado Petroleum Association and members of the Board of Weld County Board of Commissioners did not immediately return phone calls seeking comment.

– Tommy Wood covers education and Evans city government for The Tribune. You can reach him at (970) 392-4470, twood@greeleytribune.com or on Twitter @woodstein72.