Commercial naphthenic acids and the organic fraction of oil sands process water induce different effects on pro‐inflammatory gene expression and macrophage phagocytosis in mice

Abstract

Naphthenic acids (NAs) are believed to be the major toxic component of oil sands process water (OSPW). Different OSPW preparations have distinct NA compositions, and additional organics, that differ from the commercial NAs (C-NAs) often used for toxicology studies. To evaluate whether C-NAs are an adequate model to study OSPW toxicity in complex organisms, we compared the effects of C-NAs and the extractable organic fraction of OSPW (OSPW-OF) on mice immune mechanisms. Mice were orally exposed to different C-NA doses, or OSPW-OF at the same NA dose, for up to 8 weeks, and the expression of pro-inflammatory genes in different organs was determined using quantitative PCR. C-NAs and OSPW-OF altered the expression of pro-inflammatory genes, inducing either expression down-regulation or up-regulation, depending on the organ examined and time after exposure. The time at which gene expression alterations occurred, and the specific sets of genes whose expression was altered, were very different between animals exposed to C-NAs or to OSPW-OF. We evaluated the ability of mouse peritoneal macrophages to phagocytose yeast cell wall, as a measure of the ability of mice to mount a central function of the innate immune response. Phagocytosis was significantly reduced in animals exposed to C-NAs, but enhanced in mice exposed to OSPW-OF. Our results indicate that studies using C-NAs may not necessarily reflect the possible effects induced in animals by process water from tailing ponds.

Exploring the complexity of oil sands process‐affected water by high efficiency supercritical fluid chromatography/orbitrap mass spectrometry

“…4) help to explain their vastly different microbial aerobic biodegradation rates [48] as well as the different toxicological effects that these mixtures elicit in exposed organisms. [20,49,50] The different compositions also raise questions about the common practice (including in our own studies [8] ) of semiquantifying NA concentrations in OSPW and natural waters using commercial NA mixtures as standards.…”

Effect of solvent addition on bitumen–air bubble attachment in process water

“…The adsorption of ions on the bitumen appeared to be saturated at 10 wt% solvent addition, as no further reduction in ion concentration of process water was observed with the further dilution of bitumen. However, the viscosity of the bitumen was shown to continue to decrease with further increasing dilution solvent dosage , allowing more surface active materials (i.e., carboxylic acids) to accumulate at the bitumen-water interface (Allen, 2008;Garcia-Garcia et al, 2012;Liu et al, 2002). Consequently, the zeta potential of the diluted bitumen became more negative with further increasing solvent dilution of bitumen (see Fig.…”

Disruption of endocrine function in H295R cell in vitro and in zebrafish in vivo by naphthenic acids

“…However, West et al has declared that the unknown impurities in C-NAs mixtures may limit the usefulness of C-NAs for toxicity assays [55]. And also, Garcia-Garcia et al compared the effects of C-NAs and OSPW NAs in the pro-inflammatory genes expressions in mice, and found that C-NAs may not necessarily reflect the possible effects induced in organisms [56]. In the current study, we studied the endocrine disruption in vitro and in vivo assays with OS-NAs and C-NAs.…”