Development of Innovative Approaches to Assess the Toxicity of Chemical Mixtures Research Grants
EPA’s Science to Achieve Results Program (STAR) awarded $7,770,044 in research funding to 11 institutions to develop and evaluate innovative methods and approaches to inform human health risk assessment of environmental chemical mixtures.
Toxicology studies have traditionally focused on the effects of single chemicals on human health. However, people are continually exposed to mixtures of numerous chemicals present in the environment, including in air, water, soil, food, and products in commerce. These chemical mixtures include PFAS, phthalates, polycyclic aromatic hydrocarbons (PAHs), disinfection by-products (DBPs) and other well-characterized mixtures. There is a need to assess the toxicity of chemical mixtures and understand how their combined effects on our health and the environment differ from what we know about individual chemicals.
To help address this research need, the institutions listed below are conducting research focused on the development and improvement, evaluation, and integration of predictive toxicology methods to evaluate environmental chemical mixtures.
Georgia Institute of Technology – Atlanta, GA
Project Title: High-Throughput Lung Damage and Inflammation Assessment of Polyaromatic Hydrocarbon Mixtures
Principal Investigator: Shuichi Takayama
Award: $749,999
This project aims to develop a new approach methodology (NAM) to predict respiratory tract inflammation risk from polyaromatic hydrocarbon (PAH) mixtures. Researchers will test the ability to group PAHs according to a newly proposed inflammatory toxic equivalency factor (iTEF). This project is expected to develop a broadly useful NAM that is a practical, human cell-based alternative to the current rodent-based respiratory tract inhalation toxicity assessments. The proposed NAM will be used to test the ability to group PAHs according to their relative inhalation toxicities. The ability to use the resulting iTEFs of PAH components to predict joint toxicity of PAH mixtures will also be reported. Exploratory studies will reveal how much more toxic PAH-derived secondary organic aerosols are relative to their parent PAH.
Medical University of South Carolina – Charleston, SC
Project Title: Developing an Integrated Framework for Evaluating Toxicity of Real-life Chemical Mixtures
Principal Investigator: John L. Pearce
Award: $599,998
The overarching objective of this project is to improve how real-life exposure to multiple chemicals is considered in toxicity assessments of chemical mixtures. Researchers will identify real-life chemical mixtures from biological samples taken during a large epidemiologic birth cohort study. The research team will prioritize exposure mixtures using epidemiologic analysis to identify mixtures most strongly associated with child health. Researchers will also develop mixture toxicity assessments for prioritized exposures. The innovative framework will integrate exposure science, epidemiologic analysis and predictive toxicology to improve identification, prioritization, and toxicological assessment of environmentally relevant chemical mixtures. The resulting tools may provide a valuable resource to risk assessors and the broader scientific community interested in risk assessment of chemical mixtures.
Purdue University – West Lafayette, IN
Project Title: Protein Binding Affinity as the Driver for Studying PFAS Mixture Toxicity
Principal Investigator: Maria Sepúlveda
Award: $725,481
Using a combination of in silico, in vitro, and in vivo tools, this project will test the overarching hypothesis that binding of per- and polyfluoroalkyl substances (PFAS) to hemoglobin is a physiological signal for predicting the toxicity of PFAS mixtures. Using PFAS concentrations and ratios of mixtures found in surface and drinking water across the country, researchers will quantify the binding of single PFAS and their mixtures to hemoglobin. The research team will validate the models with single PFAS dose-response curves focused on quantifying changes in hemoglobin and growth rates. Then, researchers will use this data to calculate effective concentrations for each PFAS and rank them by potency. The long-term goal of the project is to produce mechanistic toxicity data for PFAS mixtures to support human and environmental health risk assessment.
The Research Foundation of CUNY – New York, NY
Project Title: Innovative Approach to Assess the Effect of Metal Mixtures from Infant Meconium Associated with Adverse Infant Outcomes by Identifying Methylation Loci in Mothers and Infants
Principal Investigator: Brian Pavilonis
Award amount: $746,154
The goal of this research is to establish a platform to quantify intrauterine exposure to metal mixtures and determine their effect on epigenetic changes in newborns. Researchers will develop a standardized method to quantify metals in meconium and implement this approach to measure metal concentrations from newborns delivered in New York City. The research team will also collect biological samples from mothers and infants and identify methylated genes for the adverse birth outcomes. Researchers will then investigate the relationship between the metal mixtures and DNA methylation. The results of this project may lead to public health actions to identify at-risk infants and develop remediation strategies. The research aims to identify changes in DNA methylation associated with exposures to metal mixtures, which could enhance the mechanistic understanding of how chemical mixtures result in human harm.
Texas A&M University – College Station, TX
Project Title: A Tiered Hybrid Experimental-Computational Strategy for Rapid Risk Assessment of Complex Environmental Mixtures Using Novel Analytical and Toxicological Methods
Principal Investigator: Ivan Rusyn
Award: $750,000
The overall goal of this project is to ensure timely, risk-based assessment of mixtures and unknown variable composition or biological substances (UVCBs) that ensures human health protection from the toxicity of known and unknown components. The research team will accomplish this goal through integration of novel toxicological, analytical, and modeling methods. Researchers will use environmental samples collected during and after natural disasters where chemical re-distribution has been documented and quantified, as well as UVCB substances. The main outcomes of this project will be a suite of analytical, in vitro, and computational methods and tools that can be applied in a tiered strategy for rapid quantitative characterization of the composition and hazards of complex environmental mixtures and UVCBs.
University at Buffalo – Buffalo, NY
Project Title: Assessment of Neurotoxicity of Mixtures of PFAS and Other Neuroactive Organic Pollutants Through Integrated in silico, in vitro Cellular, and in vivo Models
Principal Investigator: Diana Aga
Award: $750,000
This study will integrate in vitro and in silico high throughput testing with in vivo tests using a zebrafish model to evaluate the neurotoxicity of PFAS mixtures and their mixtures with other organic contaminants. Researchers will use imaging-based high-throughput tests to assess mitochondrial disfunction and disturbances of neuronal networks. Zebrafish larvae will then be used to assess PFAS effects on brain development and social interactions using a sensitized genetic background consisting of mutations in genes that are associated with autism spectrum disorders (ASD). By investigating the mechanisms underlying known effects, researchers aim to improve understanding of the neurotoxic effects of individual PFAS and how they interact in mixtures. The results of this research could be used to generate models to predict neurotoxicity of PFAS mixtures. The data generated may enable the application of adverse outcome pathway frameworks for PFAS neurological outcomes.
University of Georgia Research Foundation, Inc. – Athens, GA
Project Title: Development of a quantitative adverse outcome pathway (qAOP) network to assess neurodevelopmental toxicity of per- and polyfluoroalkyl substances (PFAS) mixture in C. elegans
Principal Investigator: Lili Tang
Award: $750,000
This project aims to develop a quantitative adverse outcome pathway (qAOP) network with advanced mixtures risk assessment for assessing developmental neurotoxicity (DNT) of PFAS mixtures at multiple levels of biological organization. Investigators will use the nematode C. elegans as an invertebrate in vivo model, which can be integrated in a manner useful to hazard and /or risk assessment. Results of this project may lead to improved fundamental knowledge on DNT testing that has not yet been conducted in-depth for PFAS. The developed qAOP network, integrated with non-mammalian C. elegans with support of statistical models, may contribute data useful for mixture-based hazard and dose-response assessments. Results of this project could advance hazard assessment of chemical mixtures and be useful resources in addressing contaminants of concern to improve regulatory decision making through greater integration and more meaningful use of mechanistic data.
University of Houston – Houston, TX
Project Title: Oral Toxicity Assessment of PAH Mixtures Using an in vitro 3D Cell Culture Bioreactor Mimicking the in vivo Intestinal Tract Environment
Principal Investigator: Debora Rodrigues
Award: $749,926
The objective of this study is to design and engineer an in vitro 3D cell culture integrated into a flow-cell bioreactor to assess the toxicity of environmental polycyclic aromatic hydrocarbon (PAH) mixtures that can be found in food. The research team hypothesizes that incorporating 3D cell culturing techniques in a bioreactor will induce growth and alter cell behavior similar to an in vivo intestinal tract environment, providing an efficient and realistic model to understand the effects of PAH mixtures on human health. This study will analyze toxicological markers and pathways of PAH mixtures. Additionally, researchers will evaluate the ability of the gut microbiome to biodegrade PAHs and whether the biodegradation by-products can cause toxic effects to the intestinal tract. Results from this study may identify toxicological markers and pathways of PAH mixtures in humans.
University of Massachusetts Boston - Boston, MA
Project Title: Whole Animal New Approach Methodologies for Predicting Developmental Effects of Air Pollutant Mixtures
Principal Investigator: Helen Poynton
Award: $750,000
This project aims to provide a novel, effects-based approach for understanding how chemical mixtures can contribute to developmental impairments. Researchers aim to develop and validate a novel whole animal new approach methodology (NAM) in crustacean embryos that targets disruptions in conserved developmental pathways through gene expression and behavioral assays for use in human health risk assessments. They will then evaluate the ability of fish and crustacean embryo tests to detect developmental toxicity to single compounds and simulated mixtures of air pollutants and compare them with predicted values from toxicological databases assuming additive toxicity. Finally, they will validate the applicability of the assays using air samples collected following open detonations of unexploded ordnance in Vieques, Puerto Rico. The proposed assays can be scaled to provide high-throughput screening of chemical mixtures from both manufactured chemical formulations and environmental samples, specifically relevant to human health. Integrating fish and crustacean assays with non-targeted analytical chemistry could provide a robust framework for identifying hidden stressors in air pollution mixtures. The approach provides new tools which may improve the risk assessment of complex air pollution mixtures.
University of North Carolina at Chapel Hill – Chapel Hill, NC
Project Title: Wildfire Smoke Mixtures Toxicity Testing
Principal Investigator: Julia Rager
Award: $599,999
This project aims to understand how individual chemicals in wildlife smoke induce in vitro responses that group according to biological pathways and inform mixtures-based joint toxicities that overlap with in vivo pulmonary responses and disease outcomes. Researchers will leverage existing chemical characterization results from variable biomass burn scenarios, representing wildfire events, to prioritize chemicals that co-occur in wildfire smoke to test for chemical groupings and joint toxicities. Lung cells from human donors will be exposed to individual chemicals, and transcriptomic signatures from exposed cells will be used to group chemicals. These chemical groups will then be tested using the same in vitro model, alongside the full chemical mixture and whole biomass smoke mixtures to compare individual chemicals, chemical groups, and whole mixture effects on pathway-level responses. In vitro findings will be strengthened through comparisons against mouse and human data to result in improved mechanistic understanding and health risk quantifications on wildfires. Results from this study may help identify geographic locations and vulnerable populations at increased risk of most harmful exposure conditions, based on biomass composition and burn scenarios.
Wayne State University – Detroit, MI
Project Title: Assessment of Underlying Molecular Mechanisms Promoting Adipogenic Outcomes in Complex Mixtures
Principal Investigator: Christopher Kassotis
Award: $598,487
Researchers will look at how chemical mixtures may impact the body’s metabolic process by examining mixtures of increasing complexity for their deviations from expected adipogenic effects of individual chemicals. They will also develop an effect-based model to predict adipogenic activity based on component bioactivities, which may provide a chemical agnostic approach to risk assessments of realistic environmental mixtures. Researchers will use in silico approaches to select chemicals predicted to promote adipogenesis through distinct mechanisms, then utilize in vitro and in vivo models of metabolic health disruption to assess both individual chemicals and their mixtures and compare with predicted outcomes based on concentration addition and independent action. The research team will use household dust samples to develop a receptor bioactivity component model to predict adipogenic health outcomes. Through testing of dust extracts, researchers expect to support a new method of mixture risk assessments through using component mechanistic effect levels to determine cooperative effects on complex health endpoints.