Screening of genotoxicity and mutagenicity in extractable organics from oil sands process–affected water

Abstract

Large volumes of oil sands process-affected water (OSPW) are produced by the oil sands surface mining industry during alkaline hot-water extraction of bitumen. It is well documented that the acid extractable organics (AEOs) in OSPW, a highly complex mixture of acidic and polar neutral substances, are acutely toxic; but few studies have examined the genotoxicity or mutagenicity of this mixture. In the present study, the in vitro SOS Chromotest and the Ames test (TA98 and TA100 strains) were used to evaluate genotoxicity and mutagenicity for whole OSPW AEOs in the presence and absence of biotransformation by rat S9 liver enzymes. Two subfractions were also examined in the same assays: neutral extractable fraction (F1-NE), and the subsequent acid extractable fraction (F2-AE). In the SOS assay, whole AEO was cytotoxic when concentrated 2× (i.e., twice as concentrated as the environmental sample) and showed increasing genotoxic response above 6×. Co-exposure with S9 had a protective effect on the cell SOS-inducing factor and survival but did not eliminate genotoxicity above 6× concentrations. Most of the cytotoxicity was attributable to F2-AE, but both F1-NE and F2-AE had similar genotoxic dose-responses above 6×. In the Ames test without S9, whole AEO was mutagenic in both strains above 10× concentrations. Co-incubation with S9 had little effect on the TA100 strain but with TA98 resulted in bioactivation at midlevel doses (1.5-6.3×) and protection at higher doses (10-25×). The 2 subfractions were mutagenic in both strains but with different dose-responses. Further research in vivo or in more relevant cells is warranted to investigate the carcinogenic risks of OSPW. Environ Toxicol Chem 2017;36:1397-1404. © 2016 SETAC.

Water quality monitoring with in vitro bioassays to compare untreated oil sands process-affected water with unimpacted rivers

“…This result is comparable to the findings of Zetouni et al (2017) 49 who reported that the bioactivation of the neutral and acid extractable fractions of OSPW occurred at REFs of 1.5–25. 49,50 The authors suggested that the reported mutagenicity was not environmentally relevant for short exposure times since the doses required for bioactivation were more than 1× the original concentration. Therefore, the long-term bioaccumulation of these compounds in aquatic organisms may be more relevant for future studies.…”

Persistent Cytotoxicity and Endocrine Activity in the First Oil Sands End-Pit Lake

“…The mobile phases were (A) 0.1% acetic acid in water and (B) 100% methanol. The elution gradient started with 5% B and 95% A for 1 min, then a linear ramp increasing the proportion of B to 90% at 9 min and to 99% B over 5 min, and finally returning to 5% B in 1 min and equilibration for 4 min …”

“…The elution gradient started with 5% B and 95% A for 1 min, then a linear ramp increasing the proportion of B to 90% at 9 min and to 99% B over 5 min, and finally returning to 5% B in 1 min and equilibration for 4 min. 34 The HRMS was an Orbitrap Elite (Thermo Fisher Scientific, San Jose, CA) operating in electrospray ionization mode and set to a nominal resolving power of 240,000 at m/z 400. For qualitative profiling of the complex organics in all water samples, two separate injections of each sample were made to allow detection of organic acids in negative ionization mode and polar organic neutrals and organic bases in positive ionization mode.…”