College of Resources and Environmental Science, National Academy of Agriculture Green Development, Key Laboratory of Plant-Soil Interactions, Ministry of Education, China Agricultural University, Beijing 100193, China.
College of Resources and Environment, Southwest University, Chongqing, 400715, China.
Environ Pollut. 2020 Feb;257:113581. doi: 10.1016/j.envpol.2019.113581. Epub 2019 Nov 8.
Soil application of Zn fertilizer is an effective approach to improve yield and Zn accumulation in wheat grain. However, it remains unclear whether repeated Zn application can result in high accumulation of heavy metals (HMs) in soils and grains and thus represents a potential risk for human consumption. This study aimed to evaluate the health risk assessment of HMs in a wheat production system which had continuously received 8 years of Zn application at varying rates (0, 2.3, 5.7, 11.4, 22.7, 34.1 kg Zn ha). The results showed that Zn application significantly increased the soil total Zn concentration without affecting concentrations of As, Pb, Cd, Cu and Cr. Across Zn rates, Zn application increased grain concentrations of Zn, Pb and Cd by 75%, 51% and 14%, respectively, and reduced grain As concentration by 14%. The human health risk assessment revealed that the threshold hazard quotients for the individual HM were below 1, independent of Zn rates. The hazard index (HI) values at Zn rates of 11.4, 22.7 and 34.1 kg Zn ha were significantly greater than that at null Zn treatment. Furthermore, exposures to As, Cu and Zn accounted for 97% of HI at all Zn rates. Analysis of the threshold cancer risk with Pb and As showed that ingestion of wheat grain even from highest Zn application rate wouldn't bring the lifetime carcinogenic risk. In contrast, long-term Zn application significantly reduced the carcinogenic risk of As by 9.7-26.5%. In conclusion, repeated soil applications of Zn at optimal rate (5.7 kg Zn ha) didn't cause health risk for Zn, Cu, Cd, Pb, Cr, and As, while improving productivity and grain Zn concentration of wheat to meet human recruitment. Our study highlights the importance of appropriate Zn fertilizer management in improving grain quality while reducing HMs risks from human consumption.
土壤施锌是提高小麦籽粒产量和锌积累的有效方法。然而，目前尚不清楚重复施锌是否会导致土壤和籽粒中重金属（HMs）的大量积累，从而对人类食用构成潜在风险。本研究旨在评估在连续 8 年施用不同剂量（0、2.3、5.7、11.4、22.7、34.1 kg Zn ha）锌肥的小麦生产系统中，HMs 的健康风险评估。结果表明，施锌显著增加了土壤全锌浓度，但不影响砷、铅、镉、铜和铬的浓度。在各施锌量下，施锌分别使小麦籽粒锌、铅和镉的浓度增加了 75%、51%和 14%，而使籽粒砷浓度降低了 14%。人体健康风险评估显示，无论施锌量如何，各单一重金属的阈值危害系数均低于 1。在施锌量为 11.4、22.7 和 34.1 kg Zn ha 时，危害指数（HI）值显著大于无锌处理。此外，在所有施锌量下，砷、铜和锌的暴露量占 HI 的 97%。对铅和砷的致癌风险阈值分析表明，即使从最高的锌施用量中摄入小麦籽粒，也不会带来终生致癌风险。相比之下，长期施锌可使砷的致癌风险降低 9.7-26.5%。总之，在最优施锌量（5.7 kg Zn ha）下，重复的土壤施锌不会对 Zn、Cu、Cd、Pb、Cr 和 As 造成健康风险，同时提高了小麦的生产力和籽粒锌浓度，以满足人类的营养需求。本研究强调了适当管理锌肥在提高籽粒质量的同时降低 HMs 对人类食用风险的重要性。
