Aurora City Council members tour Anadarko Petroluem Corp.'s drilling operations Aug. 24, 2012 at Xtreme Rig 23 in Wattenberg Field. The City of Aurora received several new drilling permit applications that could bring wells closer to residential neighborhoods. Aurora cannot ban oil and gas drilling or hydraulic fracturing, but it does jointly regulate the industry with the Colorado Oil and Gas Conservation Commission. (Marla R. Keown/Aurora Sentinel)

AURORA | Mothers living near certain levels of oil and gas extraction could be at a higher risk of giving birth to children with heart defects, according to a study published this week by a local researcher.

Lisa McKenzie, an assistant professor at the University of Colorado School of Public Health, published the article, “Congenital heart defects and intensity of oil and gas well site activities in early pregnancy,” Thursday in the peer-reviewed journal Environment International. 

The study stops short of attributing birth defects specifically to oil and gas development. But McKenzie said the study presents more evidence of a link between mothers living near busy oil and gas extraction sites and birth defects afflicting their unborn children.

McKenzie is a prolific researcher who has scrutinized industry impacts on air quality and public health for a decade.

Her work has big implications for Colorado’s booming oil and gas industry, which accounted for over $13 billion of economic activity in 2017.

Industry boosters dismissed this latest study.

“Dr. McKenzie’s studies have been called ‘misleading’ in the past, and this seems to be par for the course,” said Colorado Oil and Gas Industry CEO Dan Haley.

John Putnam, Environmental Programs Director at the Colorado Department of Public Health and Environment, said the agency needed to review the study before commenting.

“This is an extremely important topic to the department,” he said. “Currently, we are pursuing even more assertive strategies to lessen the health and environmental impacts of the oil and gas industry through the implementation of the new oil and gas laws.”

In this article, McKenzie and other CU researchers studied about 3,300 infants born between 2005-2011 in 34 Colorado counties, and the level and proximity of oil and gas extraction near their mothers’ home near the time of conception.

The study relied on state birth defects data and Colorado Oil and Gas Conservation Commission data.

The American Heart Association contributed a grant to help fund the research. McKenzie conducted the study with Stephen Daniels, the pediatrician-in-chief at CU Anschutz.

McKenzie defined “high-intensity” development with monthly data showing the amount of oil and gas produced at the nearby extraction site, taking into account whether the well was in production and the size of the well pad. Well pads can include dozens of individual wells.

Infants whose mothers lived near high-intensity extraction sites near conception were 40-70 percent more likely to have a congenital heart defect. That accounted for about 515 of the more than 3,300 total infants, McKenzie said.

She referenced some locations in Weld County as high-intensity areas.

CHDs are the most common of birth defects, according to the U.S. National Library of Medicine, and a leading cause of death. Afflictions range from blood flowing too slowly through the heart to blocking it completely. One in four children born with a CHD requires surgery or a procedure in their first year of life, according to the Centers for Disease Control and Prevention.

It is still unclear how exactly CHDs are formed, according to the study, but genetic factors may take a back seat to environmental ones.

The study suggests a link between the birth defects and emissions from oil and gas wells, such as air-borne particulate matter, as well as loud noise and the stress of living near heavy industry.

McKenzie also cites a 2016 study that found levels of benzene, a cancer-causing chemical emitted from wells, twice as high as Environmental Protection Agency standards on the northern Front Range.

The study is her first that has accounted for the intensity of oil and gas extraction. It also took into account air pollution from other sources and demographic factors.

McKenzie declined to say whether residents living near busy oil and gas sites should be worried, and recommended they speak with a doctor if they are concerned. She said it’s still “not a clear-cut answer” whether oil and gas extraction harms the public.

But she added that the latest study builds off of a growing body of scientific evidence in the field.

“It’s looking more likely that there are some health effects for populations living near oil and gas development,” she said.

Dan Haley of COGA took issue with the time period of the study. He said the network of oil and gas regulations has changed drastically since 2005, and data since then has “no relevance” to drilling practices today.

“Bottom line, the data is old and no air samples were taken. However, air samples that have been taken by Colorado’s health department, for many years now, are conclusive,” he said.

Some oil and gas emissions have reduced in Colorado, according to a 2018 report from the Colorado Department of Public Health and Environment.

McKenzie’s studies usually land with a thud in downtown Denver — flush with regional oil and gas company offices — and state government bureaus.

Most notably, McKenzie published a study last year suggesting that the “lifetime cancer risk of those living within 500 feet of a well was eight times higher than the EPA’s upper level risk threshold.” She said the research was preliminary.

Pro-industry advocacy groups often express frustration that her work is widely read by organizations and activists aiming to limit or ban fossil fuel extraction in the state.