Project 2: Toxicogenomics-based Mechanistic Multimedia Exposure Assessment and Child Development
Significance: Significant challenges remain in understanding the complex risks that pollutant mixtures and their metabolites pose for human health. These challenges motivate a new paradigm for toxicity evaluation that is based on an in vitro mechanistic and genetic pathway-based approach that allows combinations of exposures and outcomes to be tested both comprehensively and feasibly. Emerging “toxicogenomics” technologies known as high-throughput screening (HTS) monitor the comprehensive global molecular responses associated with exposure to chemicals, and have shown promise for the realization of pathway-based mechanistic and predictive toxicity evaluation without using whole-animals. These HTS in vitro molecular bioassays are very sensitive to effects that occur at concentrations much lower than those that lead to detectable effects in humans and animal models, and can aid in the quick detection of effects associated with stressors and exposures.
To address the CRECE objectives, Project 2 has developed an approach that uses in vitro HTS to measure translational changes in targeted genetic pathways occurring in response to pollutants and pollutant mixtures. Importantly, these pollutants and mixtures are drawn directly from environmental sources, such as water and air from study areas in Puerto Rico, and also from biological matrices like urine. They are then passed through in vitro preparations of human and non-human cells, where we measure biomarkers of oxidative stress, DNA damage and inflammation. These pathways and biomarkers were selected based on their established association with neonatal and early childhood health outcomes relevant to CRECE’s aims, and because the biomarkers are found at measurable concentrations in the urine and blood of exposed individuals. Through this approach, we are able to provide pathway- and sample-specific fingerprints of pollutant exposures and their effects that can inform environmental epidemiological studies and even be used on their own as biomarkers of exposure in these studies. Through close collaboration with CRECE’s other two projects, Project 2 informs epidemiological studies of our cohort of 600 Puerto Rican children. This project will provide its HTS findings and exposure biomarker measures to Projects 1 and 3, thus allowing those projects to perform health effect analyses for pollutant mixtures identified as toxic by the HTS, and to examine the association of exposure biomarkers with neonatal and early childhood health outcomes.