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What The Science Really Tells Us About That Latest Oil And Gas Study

Matt Bloom/KUNC
A workover rig in Adams County reaches into the sky. A new study from the Colorado Department of Public Health has stoked the conversation about health risks associated with living near active wells.

There's been a lot of hubbub about a recent study on the health risks of living near oil and gas. 

The Colorado Oil and Gas Conservation Commission announced it would take "immediate action" to review new permits for wells within 2,000 feet of homes. A new attack ad calls the research "junk science" and "fearmongering."  

But what did that study actually say? We took a closer look at some of the details.

The Colorado Department of Public Health and Environment paid consultants at an organization called ICF to do the study. There's a 380-page version of their findings, but we're going to focus on the shorter version, a peer-reviewed scientific paper that came out in the Journal of the Air & Waste Management Association, because that’s the standard in scientific research. 

Essentially, the question is this: Is 500 feet a big enough distance between oil and gas operations and people's homes? Unfortunately, the paper never really answers that question. But it does add to a growing pile of studies suggesting that living near oil and gas facilities might not be good for people's health, though specifics are hazy. 

What the researchers did 

The study is all about the potential risks of breathing chemicals that oil and gas operations release into the air. They're known as volatile organic compounds, and this study looked at 47 of them. 

They started with air samples taken by Colorado State University researchers at oil and gas sites in Garfield County and along the northern Front Range during drilling, fracking, flowback (where residual fracking fluid returns to the surface) and production. Then they got local weather data, including the pattern of how wind flows through mountains and valleys. They plugged all that information into a model that spit out a bunch of possible concentrations of each chemical in the air given different scenarios of weather, emissions, types of activity and duration of activity at well pads of varying sizes. 

Finally, they plugged that information into another model — a model used by the EPA to assess air pollution exposure. It basically comes up with an imaginary group of people to test scenarios on. Their characteristics and activities are based on actual census data and take all sorts of factors into account, including how quickly they breathe (based on size and gender) and the amount of time they might spend indoors vs. outdoors (based on their age, the temperature outside, and whether or not they're employed). 

"This is an impressive paper. They tried to take so many things into account," said Dr. Marsha Haley, an assistant professor of radiation oncology at the University of Pittsburgh who has written about the science behind setbacks.  

The results are some confusing measures of how all those hypothetical emissions scenarios might impact the model-people if they breathed various amounts of chemicals over various amounts of time. The findings are explained using three measures: lifetime cancer risk, hazard quotient and hazard index, which are used to understand the risk of things that aren't cancer. 

An operating drill rig in Weld County.

The findings: Cancer 

First, the cancer finding. 

The researchers estimate that if 1 million people spent 30 years living near an oil and gas facility, at most about 20 of them might develop cancer from benzene exposure. For people living exactly 500 feet away from an oil and gas facility -- and downwind from it -- less than 10 people in a million might get cancer from benzene. That drops to about one in a million or less for people living at least 1,000 feet away. 

These results fit with a 2018 study by CDPHE, which used different methods to reach similar conclusions. It found that if a person stayed in one location for their entire life, breathing in the highest simulated levels of air pollutants from oil and gas operations, their chance of getting cancer from benzene would be at most 36 in a million.

"In other words, a person in the U.S. is nearly twice as likely to be struck by lightning than he or she is to get cancer from benzene near Colorado oil and gas wells," said Tami McMullin, a toxicologist who led the study while she was working for CDPHE. 

It should be noted that, for cancer risk, the researchers only looked at benzene because it was the only chemical in the group classified by the EPA as a known carcinogen. But there are others considered probable or possible carcinogens, not to mention that oil and gas operations release additional chemicals beyond the 47 considered in the study. So, as the authors point out, "Our simulated total cancer risks from O&G operations are underestimated."

Credit Matt Bloom / KUNC News
An oil well sits alone in a field along the Rocky Mountains.

The findings: Health effects other than cancer

Now for the other pollutants, which were evaluated for their potential to cause non-cancer health problems. The researchers communicate their potential danger using two somewhat confusing measures: hazard quotient and hazard index. According to the National Academies of Sciences, Engineering and Medicine, neither of the above are actual measures of risk; they're more like benchmarks. 

A hazard quotient of 1 or less means you can assume negligible hazard, more than 1 means there's a potential for adverse effects. Here are some of the main findings on hazard quotients:

  • For 43 out of the 47 chemicals, the hazard quotients were below 1 at 500 feet from oil and gas facilities. That means that at a distance of 500 feet (the current setback standard), those 43 chemicals weren't considered worrisome, even at the worst concentrations expected.
  • But there are four more chemicals: benzene, toluene, 2-ethyltoluene and 3-ethyltoluene.
  • For chronic exposures (where someone goes about their daily life, while living near an operational oil and gas site for 30 years) higher benzene exposures led to hazard quotients slightly above 1.
  • For the worst-case scenario of acute exposure (where a person is standing outside, downwind of an oil and gas site, breathing outside air for an hour during peak emissions), hazard quotients were higher than 1 in multiple scenarios and at most distances, even at the longer distance of 2,000 feet.
  • That was especially true during flowback. Hazard quotients during that activity were way higher — as much as 22 times higher — than during production.
  • Specifically, during flowback hazard quotients jumped above 10 for 2-ethyltoluene at the current setback distance of 500 feet. That means that, for a person standing 500 feet away from an oil & gas site during that activity, the concentration of 2-ethyltoluene was 10 times higher than what you'd expect to pose a potential threat.
  • The same thing happened with benzene. Hazard quotients for that chemical jumped above 10 in a few additional scenarios, too: during drilling at 500 feet, and during flowback at 2,000 feet.

A hazard index, on the other hand, tells you if a certain combo of chemicals might team up to affect a certain organ, like the brain. As with hazard quotients, the important number is 1; a hazard index of 1 or less for a certain combo of pollutants known to affect the brain means that combo at those concentrations is unlikely to cause brain problems over a lifetime of exposure. 
The researchers looked at a number of organ systems the pollutants might impact, including the nervous system (which involves blurred vision, dampened reflexes and reduced alertness, but also "less reversible" changes in the nervous system), the blood (which involves changes in red and white blood cells), weight gain/loss, breathing problems and sensory irritation (eyes, nose, throat). 

Here are some of the main findings on hazard indices: 

  • The results actually varied depending on location: on top of a ridge in Garfield County, in a valley in Garfield County, or somewhere along the northern Front Range. They also varied depending on the kind of exposure (short-term vs. long-term) and what kind of activity was going on at the site.
  • In a nutshell, pollutant concentrations tended to be the worst along the northern Front Range and they were also worse during development, as opposed to production.
  • In most cases, the researchers found that effects on the blood were the main concern, primarily driven by benzene exposure. That was followed by effects on the brain and nervous system, which is driven by a combination of chemicals.
  • At 500 feet, the hazard index for effects on the blood got as high as 20; that happened for the scenario where someone was at 500 feet from a 1-acre well pad during flowback, and located on the northern Front Range.
  • At 2,000 feet -- four times the distance of current setbacks -- most hazard indices dropped below 10 regardless of the site or activities taking place at it. But the hazard index for effects on the blood could still be at 10 or above during flowback at the northern Front Range.

What does all of this mean? 

In some ways, the answer is in the eye of the beholder. 

"Of the many possible volatile organic compounds that could be released from an oil and gas pad, the health risks are negligible for the majority of compounds," said Tami McMullin, a toxicologist who studied the issue for CDPHE. 

Lisa McKenzie, an assistant research professor in environmental and occupational health at the Colorado School of Public Health, interpreted things differently. She's done studies suggesting that living near oil and gas well activity might affect a range of health risks including the possibility of having a baby with a heart defect

"Like our risk assessment, the (study) is predicting that there could be non-cancer health effects for people living nearer to these sites and those include respiratory and neurological effects as well as hematological effects," said McKenzie. "What's interesting here is they came to similar conclusions using a different method, which gives us more confidence in the result that there might be health risks from the air pollutants that are emitted from these sites." 

Similarly, Seth Shonkoff, an environmental and public health scientist with energy science and policy institute PSE Healthy Energy, considers this study to be one more in a growing pile of scientific studies pointing to concern.

"The vast majority of the studies out there have sort of arrived at results that indicate that there is an elevated hazard, risk or impact to public health from oil and gas development on the air pathway," he said. "That's not to say that every study has come to that conclusion, but the majority of studies have. So this is another sort of drop in the bucket that confirms results that have preceded it."

Credit Matt Bloom / KUNC News
A workover rig sits in the middle of a neighborhood on Greeley's west side. Under Colorado law, oil and gas wells must sit at least 500 feet away from homes, schools and other occupied structures.

Setback distances

The CDPHE said the new study does not determine a setback distance that is protective of public health, but it can help inform policy decisions. 

In 2013, the Colorado Oil and Gas Conservation Commission increased the state's minimum well setback from 350 to 500 feet from homes, schools and other occupied structures. 

Research has shown the current distances in Colorado and other states aren't based on data. Rather, they're set through political compromise between industry, environmental advocates and state agencies. 

After doing a deep-dive into the available data in 2014, a group of researchers with the University of Maryland School of Public Health concluded that a minimum setback distance of 2,000 feet from well pads would be the way to go, due to concerns about noise and air quality. 

A recurring theme among experts we spoke to for this story is that, given all the variables, there may not be a single distance that's considered all right.

"Using a one-size-fits-all setback distance for public health protection may not be the most appropriate way to mitigate risk," said McMullin.

"The topography, the degree of emissions — all of those things may be different well-to-well and may lead to somewhat different results from a health risk assessment or toxicological perspective," said John Putnam, the Environmental Programs Director, with CDPHE. "It's possible at some point that you look at different tools than setbacks. You could have an exposure limit, you could have a technology restriction. Setbacks may still be the right tool. There may need to be something better."

For example, there could be limits on the maximum concentration of benzene a well is allowed to emit over the course of an hour. Or, as Marsha Haley recommended in her study, a device that constantly monitors a site and creates an alert if there's a spike in pollutants. 

"So you can tell when there's a spike and get someone out there to take care of it," said Haley. "But that costs money and not everyone is willing to do that."

Credit Matt Bloom / KUNC News
Two rig workers discuss plans for plugging an abandoned well in Adams County (pictured right). The state is working to plug several hundred abandoned and orphaned wells around the state.

Industry criticism

The oil and gas industry's main issue with the new study is its reliance on three-year-old data. 

In a press conference aiming to play down concerns about its findings, Dan Haley, president of the Colorado Oil and Gas Association, called the study "outdated." He said operators are working every day to reduce their methane and emissions along the Front Range.

"Current practices now are extremely different from what was measured at that time," Haley said. "(The study's) model uses data that uses open storage tanks and different things that haven't happened in the industry in years."

Oil and gas continues to be the country's largest industrial source of the greenhouse gas methane and of smog-forming volatile organic compounds,according to the EPA. High smog and ozone have been linked to negative health effects, such as an increased risk ofasthma

Over the past decade, Colorado has clamped down oil and gas' methane emissions, with somesuccess. Since 2014 operators have cut the number of leaks each year in half, according to state data.

Despite the reduction, CDPHE staff detected nearly 24,000 leaks at oil and gas facilities across Colorado in 2018. According to the state'sannual leak count, most of them came from loose connectors, valves and pressure-relief devices at well sites. 

The count did not include the volume of methane or VOCs released into the atmosphere, and nearly all reported leaks have been repaired. 

Several studies published in recent years have correlated proximity to oil and gas production with an increased risk forlow birth weights andchildhood cancer. But so far none have proved causation. 

Despite growing concern from residents and some Colorado lawmakers, the industry maintains the position that its operations are safe. 

"This is an industry of scientists and engineers and environmental specialists," Haley said. "I truly believe we are doing it cleaner, better and safer than anyone else in the country." 

A2017 study preceding this year's health risk assessment supports Haley's sentiment. In it, researchers cross examined all of the available scientific literature on oil and gas' effects on public health with a state analysis of air samples. The samples were from regions of Colorado with oil and gas activity. 

They used the data to simulate what level of exposure people living near operations might have to a specific set of VOCs on a regular basis. Then, they looked at whether those exposure levels were above or below "safe" levels. 

Researchers concluded there was no substantial or even moderate evidence for any health effects. There was “limited” evidence for two health effects: skin irritation and asthma. 

They found "mixed" evidence for 11 health effects, including leukemia, migraines, breathing problems and musculoskeletal symptoms. Mixed evidence means there were findings that both support and oppose an association between exposure to VOCs and the illnesses. 

Dr. Mike Lumpkin, a toxicology consultant who works with Colorado's oil and gas industry, said the new study builds on the 2017 findings. He said it has given scientists some direction to look into in future research. But, he added, it has not identified actual health impacts.

"Everyone who has an interest in the veracity of science and its use in risk assessment needs to understand that," Lumpkin said. 

Credit Matt Bloom / KUNC News
An oil well sits along the Rocky Mountains somewhere near the border of Weld and Boulder counties.

What's next

Risk assessments like this latest study are predictions more than anything else; they suggest something might happen given certain exposure.

"They don't mean that anything will happen," said Liza McKenzie. "What we need to do are more studies where we actually go out and measure what people are exposed to and possibly follow them for some of these outcomes."

McKenzie says she's working on securing funding for that kind of work. In the meantime, John Putnam with the health department said state researchers are teaming up to follow up on the results of this study. 

"How frequent are these worst-case scenarios? How long do they last? That might allow us to get a better sense of how many people are exposed to them or not," he said. 

And regardless of the pollutants' health impact, Putnam added, there are plenty of other reasons to control emissions from this industry. 

"We know that they're ozone precursors and we know that the associated methane is a powerful climate driver," he said. "We have a lot of reasons to want to tighten the emissions of all of these substances."

Rae Ellen Bichell was a reporter for KUNC and the Mountain West News Bureau from 2018 to 2020.
I cover a wide range of issues within Colorado’s dynamic economy including energy, labor, housing, beer, marijuana, elections and other general assignment stories.
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