Current Research Projects

Research Project 1 - Role of open dumping and open burning of solid waste in the generation of microplastics and products of incomplete combustion on tribal lands

Background
In isolated places, limited access to standardized waste management facilities leads to the disposal of waste in open pits where the waste is usually burnt to reduce bad odors and undesired fauna. Open burning sites commonly do not reach the necessary temperatures to complete the combustion of solid waste, yielding partially combusted plastic pieces among other residues. Partially combusted microplastics may show unique characteristics in their surface chemistry that affect their interactions with the environment. Open dumping sites also generate microplastics due to the fragmentation of larger pieces exposed to environmental conditions. These microplastics may be transported to agricultural fields, bodies of water, or communities located near these disposal sites.

Our work
Our project investigates 1) the occurrence of microplastics near open dumping and open burning sites, 2) the stability and reactions of partially combusted microplastics in water and sediments, 3) the interaction of partially combusted microplastics with native plants, and 4) the occurrence of toxic organic volatile compounds resulting from burning of solid waste.

Significance
Our results will yield valuable information to understand the role of open burning and open dumping sites in the generation of microplastics and toxic organic volatile compounds.  Additionally, it will provide data to understand the effects of incomplete combustion on the stability of the microplastics in the environment. This is critical information to asses risks to communities located nearby non-standardized solid waste disposal sites.

Primary Contact
Jorge Gonzalez Estrella
Oklahoma State University

Research Project 2 - Evaluating Cumulative Environmental Exposure to Metals and Non-metals and Community-level Health Using Geospatial Modeling and Personal Exposure Assessment

Background
Tribal communities are concerned about the impact of environmental contamination on their health as well as the health of their animals. Environmental contaminants may originate from abandoned mine waste, power plants, oil and gas production, pesticide use or from open burning and dumping of trash on tribal lands which are released to the environment through different pathways: water, air, soil, and plants.  The exposure sources may lead to human and animal exposure through inhaling air, drinking water, intaking food including plants and livestock and will contribute to health disparities observed in these communities by exacerbating the risk from existing mine-waste exposure.

Our study
This study continues to assess and address environmental health disparities experienced by partner Indigenous communities through three objectives: (1) model environmental exposure that combines water, air, and soil pathways across the partner tribal communities (Crow and Cheyenne River Sioux) based on an existing geospatial model for Navajo Nation and information and data from ongoing work; (2) ground true the model through individual-level measurement of exposure using silicone wristbands sampler, GPS tracking, dietary data collection, and biomonitoring sample collection; and (3) collect community-level health survey data to examine the relation between exposure and disease.

Significance
This project will address tribal communities’ concerns about exposure risks and its effect on their health. The research is also significant in that it studies multiple exposure pathways jointly which broadens our understanding of the environmental exposure experienced by our partner communities. This will lead us as well as the partner communities to understand and evaluate the health outcomes associated with the exposure, contributing to addressing health disparities ultimately.

Primary Contacts
Joseph Hoover
Montana State University Billings

Yan Lin
University of New Mexico

Research Project 3 - Hierarchical statistical modeling and causal inference approaches to elucidate exposure pathways underlying health disparities

Background
The health disparity between the Native American population and the US general population arises from the complex interplay between multiple socio-demographic, behavior, lifestyle, and genetic susceptibility factors. The three Indigenous communities included in this study (Navajo Nation, Crow, and Cheyenne River Sioux) encounter a significant risk of exposures to environmental hazards from mine waste related metal mixture exposures, unregulated water resources, and illegal dumping and burning of refuse. These chronic exposures to metal and chemical mixtures pose a higher risk for developing chronic and fatal diseases including hypertension, diabetes, kidney disease, and types of cancer in Native American populations compared to the US population.

Our study
We hypothesize that hazardous environmental exposures along with socioeconomic status, psychosocial stress, behavior/lifestyle factors collectively influence multiple biological pathways and contribute to health disparities in Native American communities.  This project will employ data-driven and modeling approaches to understand the relative contribution of different environmental, behavior, and socioeconomic determinants to the health disparities between the native population and the US national population.

Significance
This research will develop innovative statistical methods including decomposition analyses and structural causal models to estimate the effects of risk factors at the individual and community level on the health disparities. We will investigate the environmental exposure profiles in explaining health disparities mediated through different intermediate biological pathways. We expect to identify the major contributing factors and the most significant pathways underlying health disparity, which will provide valuable information on potential targets for future intervention studies and inform cost-effective strategies to reduce health disparity.

Primary Contact
Li Luo
University of New Mexico