Incorporating source apportionment and bioaccessibility into human health risk assessment of heavy metals in a soil-rice system in the Jiulong River basin, southeast China

A positive matrix factorization-bioaccessibility-Monte Carlo simulation-human health risk assessment (PMF-BA-MCS-HHRA) model was developed to accurately assess the cumulative probability distributions of carcinogenic and non-carcinogenic risks posed by heavy metals in the soil-rice system of the Jiulong River basin, and to quantify the sources of the health risks. The results showed that natural, agricultural, industrial, and coal combustion sources were the four main sources of heavy metals. The bioaccessibilities of heavy metals through grain ingestion were significantly higher than other exposure pathways. A non-carcinogenic risk was posed by arsenic (As) and a carcinogenic risk by cadmium (Cd). The non-carcinogenic risks of heavy metals were higher for children than for adults, while the opposite was true for carcinogenic risks. The grain ingestion pathway presented the greatest health risk from heavy metals in the soil-rice system. The non-carcinogenic risks were mainly derived from industrial sources, while the carcinogenic risks primarily came from agricultural sources. Arsenic derived from industrial sources and Cd derived from agricultural sources should be prioritized for control. Grain ingestion should be considered the priority exposure pathway for control. These results provide important theoretical and practical references for human health risk assessment and source management of heavy metals in soil-rice systems.