Date of Award

2026-08-01

Degree Name

Doctor of Philosophy

Department

Environmental Sciences

Advisor(s)

Jorge L. Gardea-Torresdey

Abstract

Children are uniquely vulnerable to potentially toxic elements (PTEs), absorbing them more readily than adults and encountering them through the hand-to-mouth behaviors of early childhood. Exposure carries element-specific consequences: lead (Pb) impairs cognitive development with no established safe threshold; cadmium (Cd) damages the kidneys and reduces bone mineralization; arsenic (As) is a recognized carcinogen and developmental neurotoxicant; hexavalent chromium (Cr) is carcinogenic and induces allergic dermatitis; nickel (Ni) is the leading cause of allergic contact dermatitis in children; and excess zinc (Zn) disrupts copper absorption and causes gastrointestinal distress. Toys are a distinctive source of such exposure, yet none had been systematically assessed in the El Paso-Ciudad Juárez border region - a binational community of 2.4 million residents, including some 565,000 children under fourteen, marked by heavy cross-border commerce and a documented legacy of smelter-derived metal exposure. This dissertation presents the first systematic assessment of PTEs in children's toys sold in this region. This research reports a non-destructive X-ray fluorescence spectroscopy study used to screen 333 items collected from retail stores in El Paso (n = 109) and Ciudad Juárez (n = 224), with sampling proportional to the child population of each city. Seventy-eight percent of items contained at least one element of concern. Zn was detected most frequently (47.7%), followed by Ni (34.2%) and titanium (Ti, 28.5%); Pb, Cd, Cr, and As were also detected, with As and Cd found exclusively in Ciudad Juárez samples. Forty items (12%) exceeded ASTM F963-23 (ASTM International, 2023) and NOM-252-SSA1-2011 (Secretaría de Salud, 2012) thresholds, and jewelry constituted the highest-risk category. These findings close a longstanding screening gap and establish the analytical framework for a complete bioavailability and risk assessment, providing an evidence base for regulatory cooperation and consumer education in an integrated binational market.

Language

en

Provenance

Received from ProQuest

File Size

57 p.

File Format

application/pdf

Rights Holder

Jesus Rodriguez-Loya

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