Lead and chromium in European road paints

Abstract

Lead chromate was commonly employed as a pigment in coloured road markings until restrictions led to the development of safer alternatives. In this study, the presence and concentrations of Pb and Cr have been determined in 236 road paints of various colours sampled from streets, highways, footways and carparks from eleven European countries. According to energy-dispersive X-ray fluorescence spectrometry, Pb was detected (>10 mg kg-1) in 148 samples at concentrations up to 17.2% by weight, and above 1000 mg kg-1 yellow was the dominant paint colour. Lead concentrations on an area basis varied from 0.02 to 8.46 mg cm-2 and the metal was located at different depths amongst the samples, suggesting that formulations had been painted both recently and historically (and overpainted). Chromium was detected (>5 to 50 mg kg-1) in 81 samples at concentrations between 20 and 20,000 mg kg-1 and most often in yellow paints, and concentrations co-varied with those of Pb. These observations, and results of scanning electron microscopy coupled with energy-dispersive X-ray spectrometry, suggested that heterogeneously dispersed PbCrO4 was the dominant, but not the only, Pb-based pigment in the samples. Although there were significant international differences in frequency of Pb detection and median Pb concentrations, overall, and despite various, albeit complex, regulations, recent or extant road paint pigmented with Pb and Cr remains a pervasive environmental problem and a potential health risk in many European countries.