Nationwide monitoring of polychlorinated naphthalenes in soils across South Korea: Spatial distribution, source identification, and health risk assessment.

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The production and use of polychlorinated naphthalenes (PCNs) were banned several decades ago, but they continue to be detected due to their persistence in surface environments and ongoing emissions from combustion-related sources. This study presents the first nationwide monitoring data for PCNs in soils collected from 61 sites across South Korea. Industrial sites (mean: 127 pg/g, median: 91.4 pg/g) exhibited higher concentrations of Σ63 PCNs than urban (mean: 53.1 pg/g, median: 50.0 pg/g) and suburban (mean: 52.2 pg/g, median: 23.3 pg/g) sites. Tri- and tetra-CNs were the dominant homologues, with CN-14/24 being the most abundant congeners. The majority of PCN contamination at these sites was attributed to combustion sources and historical emissions from Halowax mixtures. Σ63 PCNs and toxic equivalencies (TEQs) were moderately correlated with the number of companies potentially emitting PCNs, industrial electricity usage, and SO2 concentrations, indicating a significant influence of anthropogenic sources on PCN contamination. The 95th percentile cancer risks for both adults and children across all sites were within the acceptable range (< 10-6) set by the US EPA. However, the higher risks observed for children underscore the importance of ongoing PCN monitoring. This study provides valuable insights into the spatial distribution and human exposure to PCNs in soils across South Korea. Based on these initial nationwide findings, comprehensive monitoring of PCNs and other dioxin-like compounds in industrial areas is recommended.