| dc.description.abstract | Microbial contamination of water systems continues to be a significant public
health concern. Evaluating human health risks associated with these contaminants and how communities perceive risks are imperative for protecting human health. This study estimated human health risks associated with exposure to contaminated well water after Hurricane Harvey flooding and at public beaches contaminated by human and nonhuman fecal sources. Well owner perceptions of well water safety and well stewardship practices three years after flooding were also evaluated.
Concentrations of the fecal indicator bacterium, Escherichia coli, and the
opportunistic pathogen, Legionella pneumophila (L. pneumophila), in well water after
Hurricane Harvey were incorporated into a quantitative microbial risk assessment
(QMRA) to estimate the risk of infection for exposure scenarios involving either
ingestion or inhalation. Derived reference pathogen doses indicated that norovirus and Cryptosporidium posed the greatest health risk for gastrointestinal infections, as the estimated median infection risk exceeded the U.S. Environmental Protection Agency (U.S. EPA) modified daily risk threshold of 1 x 10⁻⁶. The human health risks associated with exposure to L. pneumophila also exceeded U.S. EPA risk thresholds. Private well owners who participated in the survey, regardless of education, income, or county of residence, generally perceived their well water to be safe, while well stewardship practices (well water testing and well disinfection) were not routinely completed. Lastly, QMRA was utilized to assess health risks at two recreational beaches impacted by human and non-human fecal sources. Concentrations of the microbial source tracking markers-human (HF183), dog (DogBact) and gull (Gull2)-were detected at varying concentrations, yet health risk estimates at both beaches did not exceed the U.S. EPA risk of illness threshold of 0.036.
A microbial risk assessment for Texas well owners following exposure to flood-impacted wells has not been previously conducted. Evaluating well owner perceptions and well stewardship practices three years after flooding in context with estimated health risks is instrumental for risk mitigation and communication. Similarly, conducting a site-specific risk assessment characterizing human health risks at recreational beaches impacted by both human and non-human fecal sources is a targeted approach to identify pollution mitigation measures that are appropriate and effective for beach management. | |
