Lead-based paint detection using perovskite fluorescence and X-ray fluorescence

Ingestion of flakes of Pb-based paint by infants remains a health hazard with life-long consequences throughout the world. Pb-based paint was banned for residential use in the US and Western Europe decades ago but is still sold in many countries. This study evaluates the performance of a new kit for detecting exposed Pb-based paint. The kit relies on the formation of Pb-halide perovskite that fluoresces bright green under a UV flashlight after spraying a non-toxic reagent. Tests with the Lumetallix kit were conducted in parallel with X-fluorescence and inductively-coupled plasma atomic emission analysis upon acid digestion using paint currently sold in Ivory Coast and samples of older US paint. Comparison of the three different methods indicates a detection limit for the Lumetallix kit of approximately 500 ppm Pb in paint, with a sensitivity of 95% and a selectivity of 94% relative to that threshold (n=76). This detection limit is an order of magnitude below the US definition of Pb-based paint of 0.5% Pb by weight. Because the kit is easy to use, exposed paint posing a risk could therefore reliably be screened at scale by the general public. Any follow-up for confirmation and mitigation based on XRF measurements will need to consider that Pb-based paint covered with paint without Pb will not respond to the kit but will be detected through the upper layer by XRF.