Toxicity and Transcriptome Comparisons of Different Firefighting Foam Exposures in Human Renal Proximal Tubule Epithelial Cells

Details

• Personal Author:
  Beitel S ; Burgess J ; Calkins M ; Rojanasakul L ; Stueckle, Todd A.
• Description:
  Firefighters have long used Military Specification aqueous film forming foams (AFFF), containing complex mixtures of per- and polyfluorinated alkyl substances (PFAS), to extinguish liquid fuel fires. Chronic disease concerns following AFFF exposure have arisen in the fire service based on elevated PFAS levels with long half lives in firefighter serum compared to the public. Historically, elevated PFAS serum levels are linked to multiple adverse chronic health outcomes including kidney cancer. With phase out of AFFF as early as 2024 in some municipalities, replacement synthetic 'fluorine-free' foams (SFFF) are quickly being integrated into use despite limited information on potential health effects. An urgent need exists to evaluate past AFFF and near future SFFF exposures for key characteristics of carcinogens (KCCs) and underlying mechanisms of disease. The main objective of the study was to compare toxicological responses, cell signaling pathways, and functions in human renal proximal tubule epithelial cells with over-expressed OAT1 (RPTEC-OAT1) following acute exposure to select AFFF and SFFF to identify potential underlying mechanisms of disease. We hypothesized that AFFF exposure causes known PFAS-associated effects and KCCs while SFFF exposure elicits novel effects not associated with fluorine-based constituents. RPTEC-OAT1 cells were exposed for 2-24 hr to increasing doses of different products including five AFFF (A-E), six SFFF (F-H), and seven single PFAS species. High throughput multiplex fluorescent screening was conducted using a high content imager. Next, mRNA libraries were prepared from total RNA from lysed cells and subjected to RNAseq on an Illumina Novaseq. Sequences were preprocessed with adapter trimming and alignment-free quantification with Kallisto using Ensembl v96 transcriptomes. Differentially expressed genes (DEGs) for each treatment were identified with DESeq2 and uploaded to Ingenuity Pathway Analysis to identify and compare major changes in signaling pathways and cell functions. All AFFF caused significantly greater cytotoxicity than legacy PFAS species, including PFOS, on a total fluorine dose basis. Four of the SFFF were more cytotoxic than all AFFF. One SFFF sample (J) caused a dose-dependent decrease in mitochondrial membrane polarization while all other foam responses trended with cytotoxicity. Although only one SFFF sample (F) caused robust increased intracellular reactive oxygen species, several AFFF and PFAS species showed decreased antioxidant capacity. Most AFFF and SFFF caused dose-dependent shifts toward G1 phase indicating slowed proliferation. Initial RNAseq results indicate that AFFF exposure affects cell proliferation, antioxidant response, amino acid metabolism, and molecular transport functions while SFFF caused changes in pathways and functions associated acute phase inflammation and membrane functions consistent with a surfactant irritant-like response. In summary, linking phenotypic responses to transcriptomic profiles allows for phenotypic anchoring to identify modes of action of AFFF and SFFF. [Description provided by NIOSH]
• Subjects:
  Cytotoxins Firefighters Occupational Health Safety
• Keywords:
  Cell Signaling Cytotoxicity Fire Extinguishing Agents Fire Fighters Gene Expression Kidney Disorders Per- And Polyfluoroalkyl Substances PFAS Synthetic Materials
• ISSN:
  1096-6080
• Document Type:
  Text
• Genre:
  Abstract or Summary
• Place as Subject:
  Arizona ; Ohio ; OSHA Region 3 ; OSHA Region 5 ; OSHA Region 9 ; West Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  HELD - Health Effects Laboratory Division ; DFSE - Division of Field Studies and Engineering
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Volume:
  192
• NIOSHTIC Number:
  nn:20067215
• Citation:
  Toxicologist 2023 Mar; 192(S1):260
• Federal Fiscal Year:
  2023
• NORA Priority Area:
  Public Safety
• Peer Reviewed:
  False
• Source Full Name:
  The Toxicologist. Society of Toxicology 62nd Annual Meeting & ToxExpo, March 19-23, 2023, Nashville, Tennessee
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:31895a47d09edce04f1377d99a69fb0d18ff40fe0986df91cb643b41a020cbf88c00cbaf21390dc6001b51627ab51b2472e2894ae05790d42fa07f0a3ce7038f
• Download URL:
  https://stacks.cdc.gov/view/cdc/231342/cdc_231342_DS1.pdf
• File Type:
  [PDF - 1.11 MB ]