First Evidence and Source of Quaternary Phosphonium Compounds in Soil and Indoor Dust around a Manufacturing Plant

Organophosphorus pollutants pose significant threats to both human health and natural ecosystems due to their widespread use and toxicological effects. In addition to the well-known organophosphorus pesticides and organophosphate esters, quaternary phosphonium compounds (QPCs) are widely utilized, highly productive, and toxic. However, their environmental presence and behavior are not well understood. Using the cheminformatics toolkit in Python, 25 QPCs were screened as target analytes from a chemical industry database based on their characteristic structural features. Among them, 16 QPCs were detected in soil (range: 2.61–5.84 × 103 ng/g), and 11 QPCs were found in indoor dust (range: 4.89–1.71 × 103 ng/g) near a manufacturing plant. A point-source distribution pattern was observed in the soil, while indoor dust concentrations showed a distance-dependent attenuation. The spatial distribution suggests that the manufacturing plant is a significant source of QPCs in the surrounding area, with eight QPCs being reported for the first time. Human exposure assessment via dust ingestion indicated estimated daily intakes well below acceptable thresholds, suggesting limited immediate risk. This study highlights QPC manufacturing plants as a significant source of environmental contaminants and underscores the need for greater attention to plant-released QPCs and their potential health effects.