Effects of sludge compost application on soil–maize potentially toxic elements and health risk assessment

Agricultural application of sludge has become an increasingly appealing and sustainable approach worldwide. Hence, assessing the risk of sludge application is essential for informed decision‐making regarding its use in agriculture. This study primarily evaluated the ecological risks of farmland soil and the human health risks via dietary intake under sludge compost application in maize ( Zea mays L.) cultivation. Field trials were conducted with different ratios of sludge compost and chemical fertilizer, including single application of fertilizer (S0) as the control, sludge compost based on fertilizer nitrogen 20% + 80% fertilizer nitrogen (S1), sludge compost based on fertilizer nitrogen 50% + 50% fertilizer nitrogen (S2), sludge compost based on fertilizer nitrogen 100% (S3), and sludge compost based on fertilizer nitrogen 200% (S4). The potential ecological risk assessment ( R ) of soil potentially toxic elements was characterized as a slight risk level except for treatment S4, which had an R value of 164.44 (greater than 150, indicating a moderate risk level). The heavy metal content in maize grains increased with the application rate of sludge, but it did not exceed the maximum limits for contaminants in cereals (GB2762‐2017). Monte Carlo simulation was applied to estimate the total cancer risk (TCR) and health risk index for combined contamination with multiple potentially toxic elements (HI) values for both adults and children via the ingestion pathway, and HI value for adults ranged from 0.10 to 0.86, indicating low risk as values were below the reference value of 1, but the HI value slightly exceeded the safe levels for children (1.36–2.42). The TCR values for both adults (4 × 10 −4 to 3 × 10 −3 ) and children (3.9 × 10 −3 to 6.1 × 10 −3 ) exceed the safe range. This indicates that cultivating corn in farmland with excessive application of sludge compost poses health risks to humans, particularly to children. Therefore, it is necessary to conduct long‐term risk assessment research on sludge application, especially the situation of excessive application of sludge compost targeting different crops and soil types.