Toxicological profiling of real hydraulic fracturing flowback and produced water

Fracking wastewater produced developmental and aryl-hydrocarbon receptor-mediated defects in zebrafish


  • Hydraulic Fracturing flowback/produced water is a hypersaline/organic mixture.
  • A new group of aryl phosphate esters were identified in HF-FPW.
  • Acute effects of HF-FPW can attributed to both salinity and organic contaminants.
  • HF-FPW can induce EROD activity in zebrafish embryo.
  • HF-FPW displays a synergistic effect on EROD activity induction in zebrafish embryo.


Chemical and toxicological characterizations of hydraulic fracturing flowback and produced water, ScienceDirect,, 14 February 2017.

Image credit woodleywonderworks.

Hydraulic fracturing (HF) has emerged as a major method of unconventional oil and gas recovery. The toxicity of hydraulic fracturing flowback and produced water (HF-FPW) has not been previously reported and is complicated by the combined complexity of organic and inorganic constituents in HF fluids and deep formation water.

In this study, we characterized the solids, salts, and organic signatures in an HF-FPW sample from the Duvernay Formation, Alberta, Canada. Untargeted HPLC-Orbitrap revealed numerous unknown dissolved polar organics. Among the most prominent peaks, a substituted tri-phenyl phosphate was identified which is likely an oxidation product of a common polymer antioxidant. Acute toxicity of zebrafish embryo was attributable to high salinity and organic contaminants in HF-FPW with LC50 values ranging from 0.6% to 3.9%, depending on the HF-FPW fractions and embryo developmental stages. Induction of ethoxyresorufin-O-deethylase (EROD) activity was detected, due in part to polycyclic aromatic hydrocarbons (PAHs), and suspended solids might have a synergistic effect on EROD induction.

This study demonstrates that toxicological profiling of real HF-FPW sample presents great challenges for assessing the potential risks and impacts posed by HF-FPW spills.

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