Genotoxicity and Mutagenicity of Extractable Organics from Oil Sands Process-Affected Water

Abstract

Oil sands process-affected water (OSPW) is produced in the surface mining industry during the hot-water extraction of bitumen from oil-sands ore. Its acid extractable organic (AEO) fraction is known to be acutely toxic, but few studies have addressed its genotoxicity or mutagenicity. Here, the in vitro SOS-Chromo genotoxicity test and Ames test (TA98 and TA100) were used to evaluate these endpoints for the whole AEO mixture and two chemical sub-fractions (acid and neutral extractable), with and without S9 enzymes. Whole AEO showed increased genotoxicity at concentrations above 7x (SOS response of 9.63±2.11SD) where S9 fraction decreased genotoxicity by 70%. AEO mutagenicity in the TA 98 strain was similar to the TA100 strain and S9 generally decreased the mutagenicity. Genotoxicity of the acid extractable subfraction was lower than whole AEOs, with or without S9, while the neutral extractable subfraction SOS-response was the lowest and S9 presence did not significantly decrease genotoxicity. The acid extractable subfraction mutageniticy was also similar in TA98 and TA100, and S9 decreased mutagenicity by approximately half, with the TA 100 strain showing the highest mutagenicity. OSPW AEOs are genotoxic and mutagenic in the in vitro assays used here, but the mechanisms are in need of clarification and further studies examining the carcinogenic potential of OSPW are warranted.