Speciation and bioaccessibility of mercury in adobe bricks and dirt floors in Huancavelica, Peru
Background: Huancavelica, Peru, a historic cinnabar refining site, is one of the most mercury (Hg) contaminated urban areas in the world. Residents’ exposures are amplified because residents build their adobe brick homes from contaminated soil.
Objectives: The objectives of this study were to characterize the species and bioaccessibility of Hg in residential samples from adobe brick homes in Huancavelica. The goal was to evaluate potential health implications, particularly for children, following ingestion of contaminated particles.
Methods: Hg was measured in adobe brick and dirt floor samples from 60 households in Huancavelica using total Hg extractions, simulated gastric fluid (GI) extractions that are relatively easy to do, and sequential selective extractions (SSEs) that provide more detailed data but are complex.
Results: Most Hg present in samples was relatively insoluble, although in some households, soluble Hg species were present in concentrations that may be of concern following ingestion. A strong correlation was identified between simulated GI extractions for adobe bricks and dirt floors and the more soluble fractions of Hg from SSEs. Simulated GI extraction data were combined with ingestion and body mass characteristics for small children to compare risk for ingestion of Hg-contaminated soil with current health benchmarks.
Conclusions: Simulated GI extractions can be used as a screening tool to identify samples that have measureable concentrations of bioaccessible Hg that require further analysis by SSE. Combining simulated GI extraction data with health benchmarks permits intervention strategies targeted to households with the greatest potential health threat from ingestion of Hg-contaminated particles.