ABSTRACT
Yuma County is a large agricultural hub of the United States and provides over 90% of the winter leafy greens
consumed in the U.S. To maintain high agricultural output, more than 2.6 million kilograms of agrichemicals are
used in Yuma County each year. These agrichemicals represent a significant exposure source of toxic
chemicals for residents, especially the migrant and seasonal farmworkers and those living near agricultural
lands. Previous research focused on organic based pesticides and lead exposure sources, but inorganic
metals-based pesticides have not been examined in this area. I performed quantitative metal(loid) analysis of
human (n = 323) and rodent (Peromyscus eremicus, n = 300) hair samples and found concentrations of
neurotoxic metals (especially Cu and Mn) at levels known to be associated with adverse health outcomes.
Following these findings, preliminary transcriptomic analyses demonstrated disrupted genetic pathways,
including those associated with lipid metabolism and muscle contraction, in the brains of rodents that I
captured from agricultural sites, compared to non-agricultural sites, from Yuma County. Cu and Mn are
naturally occurring elements and are essential micronutrients in enzymatic reactions, but both are toxic at high
concentrations. Cu causes non-specific oxidative damage in tissues, while Mn accumulates in the basal
ganglia and dopaminergic neurons and is linked with behavioral issues in children and motor dysfunction in
adults. Farmworkers and communities near agricultural areas with high agrichemical application are an
understudied population regarding excessive Cu and Mn exposure. This proposal expands upon my
preliminary work that identified elevated concentrations of Cu and Mn in human and rodent hair collected in
Yuma County by using the P. eremicus rodent model to investigate transcriptomic and lipidomic responses to
exposure. Additionally, I am developing a similar approach in collaboration with the Cocopah Tribe in Yuma
County to assess the risk of contaminant exposure in their people. Under the guidance of a multidisciplinary
team, I aim to: Aim 1) assess effects of mixed metals exposure on brain gene expression in rodents collected
from agricultural vs. non-agricultural regions of Yuma County, using both non-targeted Nanostring and targeted
qRT-PCR approaches; Aim 2) assess effects of mixed metals exposure on brain metabolic profiles in rodents
from these two exposure regions, using liquid chromatography-ion mobility spectrometry-mass spectrometry;
and Aim 3) gather P. eremicus samples on Cocopah Tribal Lands to conduct preliminary exposure risk
assessment. This project will provide information on the neurological effects of exposure to metals used in
agriculture and aid in developing models that assess health impacts in the underserved population of
farmworkers and tribal members in Yuma County.
