PhD candidate examines groundwater contamination and toxic waste exposure in TX

Katherine Joseph, MPH, a third-year PhD student in the Department of Environmental and Occupational Sciences and a 2025 Sharma Fellow, is conducting innovative research at the intersection of environmental science and data analysis. Her work explores the relationship between toxic waste releases, groundwater contamination, and community health outcomes across Texas.

Groundwater is a critical resource for millions of Texans. However, improper use, disposal, or release of contaminants can leak into aquifers, threatening groundwater quality and safety. Small groundwater systems often lack sufficient testing and enforcement capacities, making them especially vulnerable to contamination.

Toxic waste releases, defined as any chemical that can cause harm regardless of its form, pose a threat to contaminating Texans’ clean drinking water. In 2023, the Greater Houston region had the highest pounds per square mile out of any Metropolitan Area in the country (nearly 10,000 pounds per square mile).¹

To better understand these threats, Joseph used data from the Safe Drinking Water Information System and the Toxic Release Inventory to investigate whether there is an association between volume of toxic releases and health-based drinking water violations in groundwater-dependent public water systems in Texas.

Her modeling approach estimates the associations between facility output and water quality violations from 2014 to 2024, controlling for factors such as populations served and percentage of residents living below the federal poverty level. The results help illuminate the disproportionate environmental burden faced by lower-income communities.

According to Joseph’s findings, Texas currently has 1,775 facilities releasing toxic waste, spanning 226 unique industrial categories. The top five categories include:

1. Ready-Mix Concrete Manufacturing (194 facilities)
2. Natural Gas Extraction (137)
3. Other Basic Organic Chemical Manufacturing (96)
4. Petroleum Bulk Stations and Terminals (70)
5. Other Chemical and Allied Product Merchant Wholesalers (65)

Across these facilities, 388 toxic waste chemicals were identified. Of those, 120 (30.9%) are classified as carcinogenic, and 34 (8.8%) are PFAS compounds, a class of persistent “forever chemicals” linked to significant health risks.

“Access to clean drinking water is imperative to human health,” Joseph said. “Yet, as Texas aquifers are increasingly depleted by overuse and climate change, water scarcity and contamination risks are rising—especially in low-income and rural communities.”

Joseph’s research builds on prior work by CHE faculty and spatial epidemiologist, Ryan Ramphul, PhD, MS, who found that in areas with comparable population size and poverty level, each additional oil well per square mile was linked to a 0.43% increase in health-related groundwater violations.

Joseph plans to expand her analysis to compare groundwater facilities with health-based violations by disposal method, including discharges to streams, underground injection, landfill release, and surface impoundments. She also intends to examine correlations between toxic waste disposal and air emissions, providing a more comprehensive picture of industrial impacts on Texas communities.

Through this work, Joseph aims to contribute evidence that supports stronger policies and community-based solutions for environmental justice. “We’re leveraging data to make inequities visible,” she said. “The goal is to build capacity and empower communities most affected by environmental hazards.”

1. U.S. Environmental Protection Agency.
   Toxics Release Inventory (TRI) Program: 2023 National Analysis Dataset.
   Published 2024. Accessed November 24, 2025.
   https://www.epa.gov/toxics-release-inventory-tri-program

Link to Joseph's research here.