Grantee Research Project Results
2023 Progress Report: Development of a quantitative adverse outcome pathway (qAOP) network to assess neurodevelopmental toxicity of per- and polyfluoroalkyl substances (PFAs) mixture in C. elegans
EPA Grant Number: R840453Title: Development of a quantitative adverse outcome pathway (qAOP) network to assess neurodevelopmental toxicity of per- and polyfluoroalkyl substances (PFAs) mixture in C. elegans
Investigators: Tang, Lili , Huang, Qingguo , Wang, Jia-Sheng , Shen, Ye
Institution: University of Georgia
EPA Project Officer: Aja, Hayley
Project Period: September 1, 2022 through August 31, 2025
Project Period Covered by this Report: September 1, 2022 through August 31,2023
Project Amount: $750,000
RFA: Development of Innovative Approaches to Assess the Toxicity of Chemical Mixtures Request for Applications (RFA) (2022) RFA Text | Recipients Lists
Research Category: Safer Chemicals , Health Effects , Human Health , PFAS Treatment , Chemical Safety for Sustainability , New Approach Methods (NAMs) , Mixtures , Non-Vertebrate Animal Testing , CSS , Children's Health
Objective:
This project aims to establish a quantitative AOP network with advanced mixtures risk assessment for assessing developmental neurotoxicity (DNT) of per- and polyfluoroalkyl substances (PFAS) mixture at multiple levels of biological organization using the nematode C. elegans, which can be integrated in a manner useful to hazard and /or risk assessment. The objective will be achieved through the following tasks: 1) to construct an environmentally relevant and representative PFAs reference mixture, which is the top 10 most abundant PFAS derived from the currently available data and analysis generated by Dr. Huang’s laboratory (Co-PI of the project); 2) to conduct systematic experiments to evaluate DNT of individual PFAs and reference mixture in C. elegans, which will develop a qAOP network for providing much more precision for mixture assessment; 3) to perform assessment of whole mixture in water samples by evaluating sufficient similarity to the reference mixture.
Progress Summary:
During this reporting period, we successfully completed objective 1 of this research project and published a peer-review journal paper. Initially, for the whole mixture analysis of PFAS, we constructed a reference mixture, which included ten high occurrences of PFAS in different water bodies derived from the currently available data and sample analysis generated by Co-PI Dr. Huang’s lab was constructed. The 10 PFAS selected in this study are perfluorobutanoic acid (PFBA), perfluorohexanoic acid (PFHxA), perfluorooctanoic acid (PFOA), perfluorobutanesulfonic (PFBS), perfluorohexanesulfonic acid (PFHxS), perfluorooctanesulfonic acid (PFOS), 1H,1H, 2H, 2H-perfluorooctanesulfonamidoacetic acid (NEtFOSAA), 6:2 fluorotelomer sulfonic acid (6:2 FTS), perfluorononanoic acid (PFNA), and hexafluoropropylene oxide dimer acid (HFPO-DA). The wild-type worms were exposed to individual PFAS at 0, 0.1, 1 ,10, 100 and 200 μM, and the toxic effects of PFAS on development, fecundity, and behavior at different life stages were investigated using a high-throughput screening (HTS) platform. Our results showed that PFOS, NEtFOSAA, PFBS, and PFHxS exhibited significant inhibitive effects on the growth in the L4 larva and later stages of worms with concentrations ranging from 0.1 to 200 μmol/L. PFOS and PFBS significantly reduced the brood size of worms across all tested concentrations (p < 0.05), and the most potent PFAS is PFOS with BMC of 0.02013 μM (BMCL, 1.6e-06 μM). During adulthood, all PFAS induced a significant reduction in motility (p < 0.01), while only PFOS can significantly induce behavior alteration at the early larvae stage. Furthermore, the adverse effects that occurred in larval stages were found to be the most susceptible to PFAS exposure. These findings provide valuable insights into the potential adverse effects associated with PFAS exposure and show the importance of considering developmental stages in toxicity assessments.
Finally, we determined the bioconcentration factor (BCF) of ten PFAS. Approximately 15,000 worms were treated the PFAS at concentrations of 0, 5, or 10 ppm. The PFAS were quantified using an ultra-performance liquid chromatography coupled with a triple-stage quadrupole mass spectrometer. The Bioconcentration Factor (BCF) was calculated as the ratio of the individual PFAS concentration in ng per mg wet weight (ww) of the larva (Clarva) to the measured exposure concentration in mg per L (Csolution). The results showed that PFBS has highest BCF (127.2 ± 4.7), followed by PFOSA (49.25 ± 15.66), PFOS (20.42 ± 19.22), PFHxS (14.48 ± 4.93), PFOA (7.64 ± 6.76), NEtFOSAA (3.60 ± 2.70), 6:2 FTS ( 2.37 ± 0.61), PFHxA (0.57 ± 0.16), HFPO-DA (0.31 ± 0.18), and PFBA (0.03 ± 0.005) after exposure to PFAS at 5 ppm. Similar trends were observed after exposure to PFAS at 10ppm, with PFBS having the highest and PFBA the lowest BCF.
Future Activities:
In the subsequent reporting period, we will use the putative AOP concept to guide development neurotoxicity (DNT) testing strategies in C. elegans. A suite of outcome endpoints will be employed to determine the effects of PFAS at multiple levels of biological organization in C. elegans. We will use Artificial Intelligence (AI) tools to establish high-throughput and high-content (HTHC) platform to precisely quantify the morphological alteration of neurons and synapse after developmental exposure to PFAS and its mixture. The transcriptional profiling and gene expression impacts following exposure to PFAS mixtures will be measured using RNA-sequencing platform combined with bioinformatic analyses. The learning behavior will be tested using Wormlab system. Finally, the quantitative Adverse Outcome Pathway (qAOP) of PFAS-induced DNT will be assembled based on the toxicity pathways and data from these studies. The causal relationships between each Key Event (KE) and Adverse Outcome (AO) will be verified by using functional genetic mutants of each KE. The established causal relationships between the Molecular Initiating Event (MIE), KEs, and AO will be estimated using a Bayesian network (BN) model.
Journal Articles on this Report : 1 Displayed | Download in RIS Format
Other project views: | All 1 publications | 1 publications in selected types | All 1 journal articles |
---|
Type | Citation | ||
---|---|---|---|
|
Currie SD, Doherty JP, Xue KS, Wang JS, Tang L. The stage-specific toxicity of per-and polyfluoroalkyl substances (PFAS) in nematode Caenorhabditis elegans . Environmental Pollution. November 2023.1;336:122429. |
R840453 (2023) |
Exit |
Supplemental Keywords:
PFAS, qAOP, Mixtures Assessment, Developmental Neurotoxicity, C. elegansThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.