UC GIS Week

Cross estimation of cancer incidence at census-tract level to assess risk near Superfund sites in Puerto Rico in 2020

Introduction/Background: Living near hazardous waste sites can pose an increased risk of exposure to carcinogenic chemicals. Puerto Rico (PR) has a high density of superfund-contaminated sites (27 sites across 8,900 km2). Public data is limited to municipality (county) level for privacy concerns. Hallisey et al (2017) provided cross-scale interpolation methods by accounting for census-tract population in municipality-level data. We measured the association between cancer risk and distance living from the nearest superfund site through cancer rate estimations at a census-tract level. Methods: Cancer counts (PRCCR, 2020) can be cross-estimated to a census-tract level by accounting for census-tract population size from the U.S. Census Decennial Survey (2020). Census-tract population weights were calculated by dividing the census-tract population by municipality population. Census-tract cancer counts were calculated by multiplying population weights with overall municipality counts. Census-tract centroids(n=842) distance to the nearest Superfund site were measured. A crude Poisson spatial regression model was calculated using a queen’s weight connectivity matrix. Results: The spatial regression analysis showed that for every unit increase in kilometer away from superfund site, the cancer incidence rate ratio (IRR) decreases by 1% (IRR=0.99, 95%CI: 0.9999936-0.999998). Conclusion: Even when estimating census-tract cases counts of individuals living near superfund sites in PR, we found weak associations between cancer incidence and their proximity. To evaluate more accurately the associations between proximity to superfund sites and cancer risk in PR, there is a need to evaluate the association of certain cancers data at the census-tracts level with determined carcinogens.

A Fresh Approach to Food Environment: Dollar Stores and Public Health Policy

Current United States health policy primarily targets two food environment conditions designated by the United States Department of Agriculture: food deserts and food swamps. Food deserts are areas defined as low-income areas with low access to traditional grocery stores. Food swamps are generally designated as areas with a higher concentration of fast-food and convenience store locations relative to traditional grocery stores. Dollar stores are often overlooked as a grocery source in both food environments, despite many households now opting to shop at dollar stores given rising grocery costs. Importantly, a key difference between dollar stores and traditional grocery stores is that the latter have dedicated large floorspace to fresh produce, whole grains, and lean proteins—food options that are linked to positive health outcomes. We conducted network analysis within ArcGIS Pro to determine the number of fast-food locations, convenience stores, traditional grocery stores, and dollar stores within a ten-minute drive from census tracts within metro areas of the Centers for Disease Control 500 Cities Project. Next, we formed a ratio of dollar stores to traditional grocery stores. Subsequently, we conducted a generalized linear regression within ArcGIS Pro, which showed that a larger ratio of dollar stores to traditional grocery stores was significantly associated with higher obesity rates. Our work shows the importance of considering non-traditional grocery sources, particularly dollar stores, in health policy to address health disparities and improve access to healthy food options.

Spatial distribution of organochlorine pesticide serum concentrations in Mexican children and adolescents living in and out the polluted Atoyac watershed basin

The Atoyac river basin is one of the most polluted watershed basins in Mexico. Recent studies have reported the presence of organochlorine pesticides (OCPs) in this highly urbanized region through environmental monitoring, raising concerns about potential health risks, particularly for children and adolescents. We still lack information about its human exposure through biological samples that represent a more realistic measure of OCPs body burden. To evaluate the serum concentrations of OCPs in children and adolescents living within the Atoyac watershed basin and compared them to those living outside. We included 428 individuals under 20 years old who participated as controls in a population-based study conducted in three central-southern Mexican states (2021-2024). We collected sociodemographic characteristics through face-to-face interviews and obtained serum samples in which we quantified 24 OCPs by gas chromatography. To georeference, we classified the participants as living within or outside the Atoyac basin and compared their respective serum concentrations for those OCPs detected over 10% of samples. We found two heterogeneous spatial distribution patterns of OCPs serum concentrations. HCB, dieldrin, oxychlordane, and endosulfan sulfate were higher in the Atoyac basin, with the two formers being statistically significant. In contrast, p,p´-DDE was significantly higher outside the Atoyac basin. The two patterns of exposure between the two regions emphasized one pattern driven by industry and agriculture, and the second driven by vector-borne disease control. It reinforces the need for regulation and increased monitoring in the Atoyac river basin to provide information about adverse health effects in children and adolescents.