Taina Miranda Araujo Annotations

“Also of note when interpreting our results is that this study did not take into consideration the ingestion of heavy metals through the dietary route. Had we considered this additional exposure pathway, our calculated chronic daily intake levels of heavy metals would have been greater, resulting in higher estimated risk (particularly for metals such as Pb, As, and Cd which have been widely documented in various foods)” (Marsi et al. 2021)

“Both cancer and non-cancer risk at the Census tract level exhibited positive correlations with indicators of social as well as physiological vulnerability” (Marsi et al. 2021)

This study used a community-based participatory research approach to collect and analyze a large number of randomly sampled soil measurements to yield a high spatially resolved understanding of the distribution of heavy metals in the Santa Ana soil, in an effort to exposure misclassification. This study looks into average metal  concentrations at the Census tract level and by land use type, which helps map potential sources of heavy metals in the soil and better understand the association between socioeconomic status and soil contamination (Marsi et al. 2021). 

In 2018, soil samples of eight heavy metals including lead (Pb), arsenic (As), manganese (Mn), chromium (Cr), nickel (Ni), copper (Cu), cadmium (Cd), and zinc (Zn) were collected across Santa Ana. These were analyzed at a high resolution using XRF analysis. Then, metal concentrations were mapped out and American Community Survey data was used to assess the metals throughout Census tracts in terms of social and economic variables. Risk assessment was conducted to evaluate carcinogenic risk. The results of the concentrations of soil metals were categorized according to land-use type and socioeconomic factors. “Census tracts where the median household income was under $50 000 had 90%, 92.9%, 56.6%, and 54.3% higher Pb, Zn, Cd, and As concentrations compared to high-income counterparts” (Marsi et al. 2021). All Census tracts in Santa were above hazard inder >1, which implies non-carcinogenic effects, and almost all Census tracts showed a cancer risk above 104, which implies greater than acceptable risk. Risk was found to be driven by childhood exposure.

It was concluded that the issue of elevated soil contamination relates back to environmental justice due to overlap between contaminated areas and neighborhoods of lower socioeconomic status. Marsi et al. (2021) found there needs to be more community-driven recommendations for policies and other actions to address disproportionate solid contamination and prevent adverse health outcomes.