Houston, like numerous cities across the United States, has regions where the soil is tainted by heavy metals and metalloids such as arsenic, lead, nickel, and cadmium. These pollutants are both naturally occurring and produced through industrial processes, leaching, runoff, and are often present in vehicle emissions and painted surfaces.
While certain heavy metals and metalloids—particularly zinc and copper—are essential for human wellbeing in small amounts, prolonged exposure to these substances can lead to severe health issues, such as cognitive decline, organ damage, various types of cancer, and other illnesses. Children, especially those living in urban environments, are considered to be particularly vulnerable.
A research project conducted by Texas A&M University’s School of Public Health, in collaboration with local residents, found that heavy metal contaminants were significantly elevated in a section of the Greater Fifth Ward neighborhood, located just two miles northeast of Downtown Houston.
“Heavy metals and metalloids have been thoroughly studied and regulated for over five decades. However, there is increasing evidence that exposure is more widespread than previously acknowledged, particularly in areas designated as cancer clusters like the Greater Fifth Ward, which is inhabited predominantly by socioeconomically disadvantaged racial and ethnic minorities,” explained Dr. Garett Sansom from the Department of Environmental and Occupational Health at Texas A&M School of Public Health, who co-authored the study published in the Journal of Exposure Science & Environmental Epidemiology.
Collaboration with Residents
Prior to the study’s initiation, the research team established partnerships with local environmental action organizations, the Coalition of Community Organizations and IMPACT GFW. They recruited five residents from the Greater Fifth Ward to act as block captains based on a program organized by the Houston Health Department. Each block captain worked alongside a Texas A&M student, ensuring that at least one member of each team could communicate in Spanish.
“A key strength of this research was the direct involvement of residents in designing the study, collecting soil samples, and disseminating results,” said Sansom. “This collaborative approach fostered effective communication and empowered both sides to advocate for policy changes and improvements.”
Between July and November 2021, following thorough training, the teams engaged in 12 sampling exercises, gathering a total of 193 soil samples from residential properties within the Greater Fifth Ward. After being freeze-dried and blended, the samples were sent to A&B Labs in Houston for accredited analysis of arsenic, barium, cadmium, chromium, lead, mercury, selenium, and silver concentrations.
The researchers subsequently employed statistical evaluations and reference levels set by the U.S. Environmental Protection Agency to assess cumulative cancer and non-cancer risks for both children and adults, as well as to evaluate the soil’s suitability for agricultural uses.
Findings
The analysis revealed that lead, barium, and chromium were the heavy metals found in the highest concentrations. All samples, with the exception of lead, contained levels that were equal to or below what is typically expected in urban environments.
“The median lead concentrations in seven samples from playgrounds (400 mg/kg) and three samples from residential sites (1200 mg/kg) were found to be four times higher than the general levels seen across Texas,” noted Sansom. “These figures are likely underreported, as they do not include contributions from lead-based paint or gasoline fumes.”
Residents of the Greater Fifth Ward received information about the study’s findings through mailings and a town hall meeting. Prior to this, the block captains reviewed the results to ensure clarity and comprehension. A comprehensive report was also shared with the community organizations involved.
“This study establishes a baseline that could support the development of environmental protection initiatives,” said Sansom. “Moreover, the active participation of community stakeholders was essential to the study’s success and should serve as a framework for future research involving vulnerable populations and other key stakeholders.”
The research team included Dr. Taehyun Roh from Texas A&M’s Department of Epidemiology and Biostatistics, Dr. Thomas J. McDonald, Regents Professor from the Department of Environmental and Occupational Health, Dr. Weihsueh A. Chiu from the Department of Veterinary Physiology and Pharmacology, and Dr. Leanne Fawkes, who was a doctoral student at Texas A&M School of Public Health during the study and is currently at the University of Texas School of Public Health San Antonio.
