Distribution and influencing factors of soil and groundwater pollution at pharmaceutical sites in China.

Owing to the rapid development of the pharmaceutical industry in China, contamination at legacy sites has become a major challenge that threatens the ecological environment and human health. Despite this growing concern, the distribution characteristics of contaminants at these legacy sites remain unclear. Therefore, we conducted a systematic analysis of the distribution characteristics, influencing factors, and health risks of soil and groundwater pollution at the legacy sites of 21 pharmaceutical enterprises. The results obtained identified heavy metals (As, Hg, and Pb), volatile organic compounds (VOCs) (benzene and trichloromethane), semi-volatile organic compounds (SVOCs) (benzo[a]pyrene), and inorganic salts (ammonia nitrogen and fluoride) as the major contaminants at the legacy sites. Heavy metals were primarily distributed in fill and clay layers, while the distribution of VOCs, which showed stronger vertical migration, was more diverse. Additionally, the vertical distribution pattern of the pollutants was primarily influenced by their production history, physicochemical properties, and site hydrogeological conditions. Via health risk assessment, As, Hg, and benzene were identified as major pollutants in terms of carcinogenic and non-carcinogenic risks, with the carcinogenic and non-carcinogenic (HI) risks of As (maximum value 2.97 × 10-3) and benzene (HI up to 10,200) significantly exceeding acceptable levels. Human exposure pathways included soil ingestion, air inhalation, and dermal contact. Overall, these findings serve as a reference for decision-making in risk identification and the development of pollution management and remediation strategies for legacy sites in the pharmaceutical industry.