Moderator: Melissa Smarr, Ph.D., Health Scientist Administrator, Population Health Branch, NIEHS

Abstracts

Determination of Immunotoxicity From Environmental Metal Exposures
Investigators: Jodi R. Schilz, Assistant Professor, University of New Mexico; Erica J. Dashner-Titus, Research Assistant Professor, University of New Mexico; Laurie G. Hudson, Professor, University of New Mexico

Abstract: Rarely do environmental contaminants exist as single metal exposures, thus there is a need to investigate the biological impacts of environmentally relevant combinations of metals. To date, few studies have looked at how mixed metals affect immune cells and the immune system. There has also been limited research investigating how different metal mixtures influence T-cell activation and subsequent cytokine expression. This pilot project will identify which environmentally relevant combinations of metals generate reactive oxygen species (ROS) signaling profiles in order to identify metal combinations with high potential to induce ROS-mediated immunotoxicity. We hypothesize that the metal combinations that lead to increased oxidative stress will more profoundly alter T-cell activation than individual metals or metals combinations that to not modify the oxidative stress response. Our hypothesis is based on preliminary data from immortalized T-cells (Native EH Equity Research Project 1, PI Hudson) that has shown a differential response to environmentally relevant metals capable of generating ROS. These differences in ROS signaling may relate to differential effects on T cell function and immune system function. Hypothesis 1: ROS-generating metals will function synergistically and enhance immunotoxicity.

Significance: The work will reveal whether certain mixed metal exposures are synergistic or antagonistic in modulating T-cell function and toxicity. This would inform health studies to investigate potential adverse health outcomes based on specific mixed metals exposure and help prioritize remediation strategies for certain metal mixtures to advance Native American environmental health equity. The predicted metals combinations could be tested in experimental (cell-based and in vivo models) to provide the foundations for investigations in exposed populations. Lastly, the work may inform development of new biomarkers for toxic metal exposure that could aid the prioritization of metal exposure health assessments in community members and education on how communities might avoid or minimize exposures.

Characterization of Unregulated Watering Wells in the Tsétah Area and Surrounding Communities and the Further Development of Metal Selective Composites As Potential Remedies
Investigator: Ranalda L. Tsosie, Ph.D., (Diné), NSF EAR Post-doctoral Fellow, Research Faculty, Montana State University

Abstract: This project will obtain a geochemical profile of the water that is flowing from wells in the Tsétah area to aide in the investigation of possible remediation techniques for contaminated ground and surface waters. In an effort to address the long-standing health hazards imposed by abandoned uranium mines and groundwater contamination, it is proposed here to bind and remove trace metal contamination from these wells using Silica Polyamine Composites (SPC). SPCs have been used to filter, isolate, and remove unwanted metals, in particular uranium and arsenic, by acting as a chelating agent and have been primarily used in recovery of metals from leachates in the mining industry.

Significance: The importance of this research is to better understand the water contamination of unregulated wells in the Tsétah area in the communities of Red Mesa, Sweetwater, Immanuel Mission and western Teec Nos Pos in northeastern Arizona. These communities are impacted by the legacy of abandoned uranium and vanadium mines. Further studies are needed to thoroughly understand the interactions of the aqueous geochemistry of uranium and other components present in water and to find a solution to address the contamination issues in the Tsétah area. While well water use in the Tsétah area is limited to consumption by livestock and for agricultural purposes, the elevated levels of uranium, arsenic and vanadium can still pose a health risk when considering the possible bioaccumulation of these elements by both plants and animals. In addition, despite caution signs for consumption dangers are posted at wells that have elevated levels of contaminates, there are still families that are accessing these water sources because the signs are not placed in appropriate locations.

Effect of Water Chemistry and Fungi-plant Symbiosis on Arsenic Uptake and Toxicity  
Investigator: Cherie De Vore, Eliane El Hayek, Taylor Busch, Benson Long, Mehdi Ali, Michael Mann, Jennifer Rudgers, Tamara Howard, Adrian Brearley, Michael Spilde, Patrick Hudson, Carlyle Ducheneaux, Jose M. Cerrato 

Earth Systems Science, Stanford University 
Department of Civil, Construction and Environmental Engineering, University of New Mexico 
Earth & Planetary Sciences, University of New Mexico 
Department of Biology, University of New Mexico 
Cell Biology and Physiology, Health Sciences Center, University of New Mexico  
Department of Environment and Natural Resources, Cheyenne River Sioux Tribe  

Abstract: Understanding the biogeochemical processes affecting the accumulation of metals in plants is important to determine environmental exposure pathways and to inform appropriate phytoremediation strategies. We integrated microscopy, spectroscopy, culturing and molecular biology, and aqueous chemistry techniques to evaluate arsenic (As) uptake in hydroponically grown Schizachyrium scoparium (little bluestem) inoculated with endophytic fungi. Schizachyrium scoparium grows in historically contaminated sediment in the Cheyenne River watershed and was used for laboratory hydroponic experiments with As(V) ranging from 0-2.5 mg L^-1 at circumneutral pH. Arsenic uptake in regional plants has been a community concern for several decades, yet mechanisms affecting As uptake in plants associated with endophytic fungi remain poorly understood. Our results suggest that: 1) precipitation of Ca phosphate minerals on root surfaces can facilitate As adsorption in the cell walls through surface complexation and co-precipitation, enhancing As accumulation in the roots; 2) endophytic fungi supported better external and vascular cellular structures that facilitate As intracellular uptake; and 3) the surface precipitation of hydroxyapatite in the roots resulted in As adsorption and co-precipitation.

Significance: Our findings provide new insights regarding biological and physical-chemical processes affecting As accumulation in plants at contaminated sites for risk assessment applications and bioremediation strategies.  Ongoing and future work is focused on investigating the impact of the co-occurrence of metals (for example, As and Uranium) and organic (for example, microplastics) contamination on the bioavailability and toxicity mechanisms of these contaminants in plants.