MS in Environmental Engr. (M.S.E.V.)
Degree Granting Department
Civil and Environmental Engineering
James R. Mihelcic, Ph.D.
Stewart Oakley, Ph.D.
Katherine Alfredo, Ph.D.
Developing Country, Hazard Quotient, Low-level Arsenic Exposure, Public Health, Sustainable Development Goals
Lake Atitlan, Guatemala acts as a sink for wastewater discharge and as a source of drinking water. The populations living in the lake basin are primarily indigenous with a large percentage (70%) living in poverty. Wastewater effluent entering the lake poses an immediate health risk to those using it as a drinking-water source. Additionally, the lake is surrounded by three volcanoes and the water has concentrations of naturally occurring arsenic above the recommended reference level of 10 µg/L. Arsenic is acutely poisonous at high concentrations and has carcinogenic and neurological effects when chronically exposed at low concentrations.
The goal of this thesis is to improve the health of communities living around the lake by informing policy surrounding the lakes management. This is done by quantifying the burden of disease due to low-level arsenic exposure and acute diarrheal disease using disability adjusted life years (DALYs), the hazard quotient (HQ), and the relative health indicator (RHI) method in three municipalities; Santiago Atitlán, San Lucas Tolimán, and San Pedro La Laguna. Diarrhea was used as an endpoint for diarrheal disease and arsenic-induced lung and skin cancer were used as endpoints for low-level arsenic exposure.
The results of the assessment indicated that policymakers should prioritize microbial contamination mitigation strategies and treatment to improve public health. For a scenario where a 3-log pathogen removal and some residual chlorine was considered, the absolute difference was 14.79. The RHI associated with reducing the mean concentration of arsenic in the lake (18 µg/L) to the MCL resulted in a 2.67E-4 reduction in RHI. Policy could focus on increasing awareness, sponsoring treatment technologies in schools, and exploring options for the construction and operation a treatment plant.
The results of the DALY assessment found that diarrheal disease had the largest contribution to the total burden of disease (0.227 per person-years) (99%<) and that children <5 years of age carry the largest disease burden associated with diarrhea (90%). Additionally, even at low concentrations (<30 µg/L), arsenic exposure poses an excessive lifetime risk for the development of cancer (2.01E-4 per person-year DALYs). The HQ was determined to be ≥ 1 for all scenarios considered, meaning that there is a heightened risk for the development of non-carcinogenic effects of arsenic exposure such as decrease in IQ. Although the DALY results should not be directly compared due to the nature of each disease (i.e., chronic versus acute effects) they show that both contaminants are above the tolerable burden of disease and must be mitigated.
Drinking-water treatment plants are needed to fully improve and protect the health of population. However, they are expensive and take time to develop and fund. More research is needed on low-cost, culturally appropriate technologies for the region for drinking-water treatment plants with specific processes for pathogen reduction and arsenic removal. Arsenic and pathogen removal can occur simultaneously and a potential water treatment process would include oxidation by ozone, coagulation and flocculation, filtration, and chlorination.
The burden of disease can be immediately mitigated by focusing interventions on the <5 age group as they are most at risk of the non-carcinogenic effects of arsenic and diarrheal disease. Point of use treatment in the home (boiling, sand filters) and at schools are important starting points in combatting the effects of diarrheal disease. Locals should continue to be engaged on the importance of drinking water and sanitation to improve health and should be part of the decision-making process of constructing and operating a drinking-water treatment plant.
Scholar Commons Citation
Alvarez, Marisol, "Health Risk Assessment of Local Populations Ingesting Water with Naturally Occurring Arsenic and Fecal Related Contaminants in Lake Atitlan, Guatemala" (2021). USF Tampa Graduate Theses and Dissertations.