The Colorado Department of Public and Environment and Pennsylvania Department of Health recently teamed up to analyze studies claiming to link health impacts to oil and natural gas development. What they found is in line with similar analyses: There is  “insufficient weight of evidence” to link living near oil and natural gas production sites with poor health outcomes.

The two health departments reviewed 20 epidemiological studies, with 32 different health outcomes, finding:

“Since only a few outcomes were covered by multiple studies, there was insufficient weight of evidence for most health outcomes. We found studies of populations living near ONG operations provide limited evidence (modest scientific findings that support the outcome, but with significant limitations) of harmful health effects including asthma exacerbations and various self-reported symptoms. For all other health outcomes, we found conflicting evidence (mixed), insufficient evidence, or in some cases, a lack of evidence of the possibility for harmful health effects.” (emphasis added)

CDPHE and PADOH consistently described these studies as having “low certainty” and “insufficient weight of evidence,” undercutting the studies’ claims that people suffer worse health outcomes just because they live near oil and gas operations.

Majority of Studies Were Rated “Low Certainty”

In a review of their methods, CDPHE and PADOH explained the confidence levels of the various studies and health outcomes. The results speak for itself:

“Across all health outcomes, four of the 20 studies received a moderate level of certainty rating. All others received a rating of low certainty.”

The majority of findings from the studies were ranked as low certainty, primarily due to limitations of the study designs that make it difficult to establish clear links between exposures to substances potentially emitted directly from ONG operations and the health outcomes evaluated. These limitations are inherent to observational epidemiologic studies and include indirect exposure measurements, confounding bias, and subjective methods to determine health outcomes.” (emphasis added)

The analysis looked at two studies analyzing birth defects and nine on adverse birth outcomes, finding:

These low-certainty studies resulted in insufficient evidence to determine if living near ONG operations during pregnancy is associated with birth defects since there was only one study per outcome.”

“Overall, there are conflicting findings across studies resulting in either mixed or insufficient evidence of adverse birth outcomes associated with living near ONG operations during pregnancy.” (emphasis added)

The health departments analyzed three studies on cancer, finding:

“We identified seven low certainty study outcomes from three studies that assessed the relationship between living near ONG operations and the likelihood of developing cancer. … Overall, the weight of evidence is insufficient for all but one of the cancer outcomes since there is only one study for each. There is mixed evidence for childhood leukemia owing to conflicting study findings.” (emphasis added)

“[T]he development of cancer is complex because many other non-environmental influences, such as genetics and lifestyle behaviors, also contribute to cancer risk.” (emphasis added)

Similarly, respiratory health outcome studies were found to have conflicting evidence. Out of 11 studies, only one was ranked as “moderate,” while the rest received “low certainty ratings.” Four neurological studies were also found to have limited or conflicting evidence to support their claims.

Other Factors at Play

CDPHE and PADOH also explain in the analysis that one major limitation of these types of epidemiological studies is their lack of consideration for other factors that may be influencing health outcomes in a region. For examples, how close some lives to other industries and centers commerce:

“Measures of mental health are not necessarily a result of direct exposure to substances emitted from oil and gas operations but could be indirectly associated with non-chemical environmental stressors such as noise, light, odors, or social stress of living near a hotly debated, politicized, and potentially risky industry. For example, studies have shown associations between living in areas with increased noise and traffic, such as by airports, with increased psychological symptoms.” (emphasis added)

It also describes:

“Additionally, there may be many other environmental sources of emissions for air pollutants including vehicles and wildfires.” (emphasis added)

Analysis Rebuts Studies From Anti-Fossil Fuels Groups

 This analysis is timely, given that “Keep It In the Ground” groups, Physicians for Social Responsibility and Concerned Health Professionals of New York, recently released their updated annual compendium of health studies that includes the very studies analyzed by CDPHE and PADOH.

Each year the groups compile a list of any studies published that claim fracking is impacting health, and as EID has pointed out previously, noticeably absent are those studies that take actual measurements resulting in contradictory findings. This discrepancy between studies taking air and water samples and those that PSR and CHPNY include in their compendium was recently discussed in a report co-authored by Seth Shonkoff, the activist who wrote a 2012 memo encouraging anti-fracking groups to connect health problems and fracking even when no evidence existed to support the claims. Notably, even Shonkoff admitted that the vast majority of scientific research shows no harmful air pollutants near oil and natural gas sites, explaining in the report:

“Air pollution near oil and gas production typically measures in concentrations within healthy air standards…”


This CDPHE and PADOH analysis builds on prior analysis that similarly have found significant limitations with the epidemiological research claiming that oil and natural gas development is having negative health impacts on nearby populations. For instance, another CDPHE analysis ranked the majority of recent studies purporting to find a link between oil and natural gas activity and adverse health effects as “low quality, primarily due to limitations of the study designs that make it difficult to establish clear links between exposures to substances emitted directly from oil and gas and the outcomes evaluated.”

“Keep It In The Ground” activists have pushed out flawed studies to support their agenda of fracking bans and moratoriums, but independent analysis have shown that they aren’t scientifically sound.