Groundwater Arsenic in Chimaltenango, Guatemala

In the community of Cerro Alto, in the municipality of Chimaltenango, Guatemala, we collected water samples in 2009 from two wells. Arsenic concentrations found were greater than four times the World Health Organization (WHO) provisional guideline value for arsenic in drinking water of 0.01 mg/L. As a result, we returned to work with local public health authorities and characterized the presence of arsenic in the groundwater of the entire municipality. A total of 42 samples were collected from 27 of the 62 (43.5%) wells in the municipality in January 2012. Upon analysis, the only site found to have a concentration above the 0.01 mg/L WHO guideline was Cerro Alto, where the average concentration was 0.0475 mg/L, similar to our initial finding in 2009. Arsenic contamination of groundwater can often be attributed to a naturally high presence in the area. Using data from the US Geological Survey and our GPS data of the sample locations, we found Cerro Alto to be the only site sampled within the tertiary volcanic rock layer, the likely source of arsenic in Guatemala due to the linkage between volcanic rock and naturally occurring arsenic. A risk assessment based on the arsenic levels found in Cerro Alto showed an increase in noncarcinogenic and carcinogenic risk for residents there. Recommendations are described to eliminate or lower the levels of arsenic found in the community’s drinking water.