Hannah Kazis-Taylor

A recent Yale study of 1,021 known chemicals in fracking fluids and wastewater raises alarm about the substances’ public health impacts.

Of only 240 substances with sufficient epidemiological data to assess the probable health effects, a large majority of the known chemicals were found to have probable reproductive or developmental toxicity, or both. The greater threat, however, rested in chemicals unidentified, noted lead author Elise G. Elliott Ph.D.’18.

“Looking beyond hydraulic fracturing, the public should be alarmed that there are nearly 85,000 chemicals in use in industry, but the best reproductive toxicity database contains only 5,000 entries,” said Desiree Plata, professor of chemical and environmental engineering with knowledge of the study.

Researchers involved in the study highlighted the opaqueness of the oil and natural gas industry’s disclosure practices. Nicole Deziel, study co-author and epidemiology professor, said the full spectrum of chemicals used at private fracking sites remains unknown to the public and out of the U.S. Environmental Protection Agency’s inventory.

Hydraulic fracturing — a method of extracting natural gas by pumping in fluids to break shale rock in earth’s crust — requires introduction of undertested chemicals to the earth, which could arrive in water sources along with heavy metals from the inner ground.

“Fracturing wastewaters are composed of fracturing fluids plus transformation products plus materials extracted from the shale horizon; it will inevitably be a very complicated mixture with lots of inter-well variability,” Plata said. Public health toxicity studies on specific chemicals, she noted, are logistically difficult and prohibitively expensive tocomplete.

The publication in Nature Journal of Exposure Science & Epidemiology on Jan. 6 therefore sought to prioritize chemicals for water quality tests at local sites, and potentially for regulation.

Researchers culled large quantities of data from REPROTOX toxicity databases to determine whether toxins found in both fluids and wastewater likely had a causal relationships with adverse developmental and reproductive outcomes.

Elaborating on those outcomes, Elliott noted that the adverse reproductive and developmental outcomes included birth defects and neurological aberrations, among other developments.

“Some of the animal studies that were recorded in the data that we referred to looked at trends in the number of offspring in reproductive circumstances. It was a wide range of adverse health outcomes that were taken into account,” Elliott said.

Nonetheless, the unknown chemicals remained the greatest concern. Plata noted that a toxicity-based priority list automatically biases one toward study of established, measurable chemicals, when others may have larger health impacts.

Researchers acknowledged that the study failed to account for air pollutants potentially released at fracking sites. Plata, who published a study this December finding that the toxic repercussions of deep fracturing are dwarfed by fracking’s surface-level processes, noted that the toxicity of air pollutants went unexamined in this study.

“These would take two forms: the volatile organic compounds (VOCs) that outgas at the surface, including benzene, and naturally-occurong radioactive materials (NORMs) that outgas when shale fluids are brought to the surface,” she said in an email to the News.

On the whole, all authors interviewed agreed that conclusions cannot be made until individual tests have been conducted to determine these toxins’ presence in drinking water.

“Elliott et al. have laid out the risk, now it is time for others to assess the exposure,“ Plata said.

Hydraulic fracturing is used to extract methane, a greenhouse gas.