Researchers from the Yale Schools of Public Health, Forestry and Environmental Studies and Engineering and Applied Science are joining forces to launch a new study on the health effects of hydraulic fracturing, also known as fracking.

Led by epidemiology professor Nicole Deziel, hydrology professor James Saiers and chemical and environmental engineering professor Desirée Plata, this three-year project will investigate how hydraulic fracturing — a method of oil and natural gas extraction — may lead to drinking water contamination and adverse birth outcomes.

The study will be funded by a $2 million grant from the Environmental Protection Agency. Other collaborators on the project include environmental health professor Michelle Bell, epidemiology professor Xiaomei Ma and biostatistics professor Joshua Warren.

Hydraulic fracturing involves pumping large volumes of highly pressurized fluid into rock layers deep below the surface of the Earth. This procedure creates fissures in the rock that allow oil and gas to flow more freely. After substantial development over the last decade, the oil and gas industry has attracted controversy from activist groups that object to the impact of hydraulic fracturing on the environment and human health.

In the process, however, significant amounts of wastewater are also generated, carrying many potentially harmful chemicals back to the Earth’s surface, Plata said.

“When you look at a list of almost a thousand different types of chemicals used in fracking, only a relatively small proportion of them have known assessed toxicity information,” Plata said. “While there’s a lot known about those chemicals, there are also some huge windows of uncertainty. This project is really trying to understand where relative exposure is likely to occur and which homes and populations are at risk of being impacted by a big exposure event.”

According to Deziel, this will be one of the first studies to examine the connection between potential water contamination and adverse birth outcomes related to hydraulic fracturing. Other researchers have explored hydraulic fracturing and neonatal health, but they focused on air quality rather than water measurements, she said. In addition, she noted that these studies did not involve taking quantitative measurements of the possible chemicals that could be driving these associations.

Saiers added that although there have been some recent advances in understanding the potential impact of hydraulic fracturing on water quality, there has not been much progress in connecting advances in the physical science and engineering arenas with health impacts.

Existing research on the human health effects of hydraulic fracturing has also not been comprehensive, Saiers said. For example, some previous studies used proximity to well sites as a metric of exposure to potentially hazardous chemicals. However, proximity by itself does not account for the complex flow paths and mechanisms that deliver contaminants from fracking sites to drinking water receptors, he added.

“Generally, this type of research occurs in silos, where chemists are doing their own studies while geologists and public health scientists are doing other work,” Deziel said. “[This project] is uniting these different disciplines to really try to better understand the complexities of this industry and the potential impact on water and health.”

Plata added that she looks forward to seeing how each researcher will bring a unique skillset to the project. For example, she noted that environmental chemists and geochemists often have difficulties proving causal relationships, so team members from the School of Public Health will be able to contribute rigorous statistical and epidemiological analysis to understand the correlation between chemical exposure and public health outcomes.

On the other hand, epidemiologists benefit from environmental chemists by having accurate exposure measurements, which are not often available or directly coupled to public health reports, Plata said.

According to Deziel, the team hopes to provide policymakers, researchers and public health officials with useful tools to help determine whether the hydraulic fracturing industry is proceeding safely. One aspect of the project will involve creating a model that better predicts which homes may be more vulnerable to drinking water contamination. This tool could help local health officials do more informed, targeted monitoring and sampling of drinking water sources, Deziel said.

“It’s likely that unconventional oil and gas development is going to continue for quite a long time, so I think it’s critically important that we do it safely and thoughtfully,” Saiers said. “In order to regulate [hydraulic fracturing] properly and understand the risks, we sorely need additional data. Right now the data are beginning to emerge, but we still have a lot left to learn.”