Metal(loid) concentrations in drinking water and public perception of water quality in the Arizona–Mexico border

Using the social determinants of health (SDOH) framework, this community-engaged study took place in Nogales and Naco, Sonora, Mexico, located along the US-Mexico border region. This study aimed to investigate the relationships between drinking water quality, perceptions, and socioeconomic factors that influence exposure pathways to metal(loid)s and create vulnerabilities. A mixed-methods approach was employed, combining environmental/health surveys and analyses of 19 metal(loid)s in 60 drinking water samples collected from public sources, private wells, and pipas. All 19 metal(loid)s were below the U.S. maximum contaminant level (MCL) and Mexico standards, except for one sample with an antimony concentration of 6.43 µg L⁻¹. Twenty-three percent of the samples were below or above a pH of 6.5–8.5, and 100% and 98% of samples exceeded the MCL goal of lead and arsenic, respectively, highlighting a potential risk of chronic exposure. Participants generally had a negative perception of water quality, frequently describing it as intermittent, unreliable, dirty, or unsuitable for drinking. Consequently, many relied on purchased bottled water for drinking, cooking, and cleaning. Despite efforts to minimize exposure, some participants worked in occupations with heightened risks of exposure, and 99% reported residing near a potential pollution source. By applying the SDOH framework, this study goes beyond solely evaluating water quality by also exploring the underlying structures and systems that influence water access, usage, perceptions, environmental behaviors, vulnerabilities, and public health outcomes.