MEASUREMENT OF THE IN VITRO TOXICITY OF PRODUCED WATERS
In the present study, we investigated the effects of hydraulic fracturing flowback waters from eight sites on human cells. Toxicity at full-strength and 1:10 was severe for four sites sampled and in full-strength only for two additional sites. In a post-injection time series exposed cells were 20% viable. An intensive study of a subset of two samples revealed severe, significant wound closure inhibition occurred at 1:10, remaining significant at 1:100 but without effect at 1:1000. Cells behind the wound edge lost cell-cell continuity indicating aberrant healing. At 1:100, glutathione transferase kappa (GSTκ1) and arylhydrocarbon receptor (AhR) proteins were increased. AhR is a transcription factor activated by many toxic contaminants including dioxins. Mice engineered to lack GSTκ1 develop glomerulonephropathies therefore loss of function could compromise contaminant detoxification, leading to renal impairment. GSTµ1/2, involved in protection against oxidative stress and DNA damage repair, and CYP1A1 (AhR ligands regulate mRNA expression of CYP1A1) protein expression decreased similar to a known kidney carcinogen. Although it is unclear whether accidental discharges will occur, the possibility remains and recycling or treatment, if possible, could forestall toxic consequences.