Cadmium contamination in urban paints in Quito, Ecuador: in-field pXRF screening of exterior surfaces and road markings

Cadmium (Cd) has been used as a pigment in the paint industry because of its bright colors and durability. However, the degradation of paints through weathering, abrasion, and aging, or their improper disposal, contributes to the release of Cd into the surrounding environment, thereby contaminating air, soil, and water systems, reaching the food chain, and ultimately affecting human health. This study aimed to present, for the first time, an overview of the presence of Cd in paints applied to exterior walls, public spaces, and streets in a densely populated area of Quito, Ecuador. A total of 171 painted spots were analyzed in-field using a portable X-ray fluorescence (pXRF) spectrometer. Results showed that 56 spots exhibited detectable Cd concentrations, ranging from 27 to 2262 mg/kg. Of these, 30% of road-marking paints and 19% of wall paintings exceeded the threshold limit of 100 mg/kg established by the Commission Regulation (EU) 2016/217. Yellow, red, and orange paints showed the highest Cd content in several samples. This first screening confirms the presence of Cd in commercial paints regularly used and stands out the need of national regulation for Cd in paints, as well as the implementation for stricter controls on domestic and imported products, monitoring of raw materials, and continuous surveillance of Cd in paints to reduce human exposure.