From concentration patterns to source attribution and health risk: clarifying the evidential chain in Durgapur road...

This Correspondence examines the evidential chain linking chemical measurements, source attribution, spatial interpretation, and human-health risk assessment in the recent study of potentially toxic elements (PTEs) in roadside dust along NH-19 in the Durgapur Industrial Area, eastern India, by Koley et al. (2026). The study combines ICP-OES analysis, scanning electron microscopy, geochemical indices, spatial interpolation, Pearson correlation, principal component analysis (PCA), hierarchical cluster analysis (HCA), and health-risk calculations. The integrated approach is valuable, but several points require clarification before the strongest conclusions can be reproduced and interpreted consistently. The published Abstract reports mean concentrations of Fe, Mn, Zn and Cr that differ substantially from the means reported for the 14 composite samples in Table 3, and it also reports children's hazard-index values that differ from Table 8. The description of 14 composite samples collected in triplicate versus n = 42 in the Abstract also requires explicit identification of the statistical unit used in multivariate analyses. Further, PCA and HCA provide source associations rather than quantitative source contributions; the < 63 μm laboratory fraction should not be equated with an inhalable PM fraction; and total concentrations provide screening-level rather than exposure-dose estimates when bioaccessibility and chemical speciation are not measured. Finally, the text describing the carcinogenic assessment does not appear to correspond to the elements for which TCR values are displayed in Table 8. These clarifications would strengthen the transparency, reproducibility and environmental-health interpretation of the study.