Toxic effects induced in mammalian immune cells after in vitro exposure to oil sands process-affected water and its fractions

  • Author / Creator
    Phillips, Nicole AI
  • Oil sands process-affected water (OSPW) is produced by the surface mining industry in Alberta as a byproduct of the Clark hot water process, the currently used extraction method of crude oil from bitumen/tar sands. Under a provincial zero release policy all produced OSPW must be stored on site. The footprint and volume of stored OSPW represents a difficult environmental challenge. The characterization of OSPW toxicity is critically important for remediation efforts, as well the protection of ecosystem and public health. Chemical analysis of OSPW indicates a highly complex mixture of over 400 constituents of both organic and inorganic origin. OSPW can be physically separated into the organic fraction (OSPW-OF) and inorganic matrix (OSPW-IM). Exposure of test organisms to the organic fraction of OSPW impairs immune function at a cellular and organismal level. These effects include both stimulatory and suppressive deviations from homeostasis which may lead to increased susceptibility to infection and chronic inflammation. It is well established that the naphthenic acid containing OSPW-OF induces dose-dependent toxicity in aquatic and terrestrial organisms. In contrast, the potential toxic effects of the OSPW-IM remain to be comprehensively examined. The overall objective of my thesis was to evaluate the toxic effects in mammalian immune cells exposed to OSPW-IM.

    The effects induced by the whole (crude) OSPW, OSPW-OF, and OSPW-IM were compared in vitro using the RAW 264.7 macrophage-like cell line and a number of different bioassays. The results showed that acute exposure of cells to OSPW-IM significantly affected cellular viability, metabolism, gene expression, protein synthesis and function. The magnitude of toxic effects induced by exposure of cells to the OSPW-IM was similar to those induced by whole OSPW and not OSPW-OF. The exposure to either the whole OSPW or OSPW-IM caused functional changes in macrophages that may profoundly influence the ability of the host to maintain homeostasis and/or control exposure to pathogens. The gene expression analyses in conjunction with enzyme abundance and function revealed that whole OSPW and OSPW-IM possessed immunomodulatory properties causing changes in macrophage polarization status.

    The results of my thesis research represent the first comprehensive analysis of the toxic effects of OSPW-IM and its contributions to the overall toxicity of whole OSPW, using multiparametric analysis of toxicity caused by complex xenobiotic mixtures.

  • Subjects / Keywords
  • Graduation date
    Fall 2019
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
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