Heavy Metals and Naturally Occurring Radionuclides in Agricultural Soils from Phosphorus Fertilizers: A Review

The aim of this study was to summarize and critically assess available data on the content of heavy metals (HM) and naturally occurring radionuclides (NOR) in mineral phosphorus fertilizers, their entry into agricultural soils, and associated ecological and human health hazards. The systematic Scopus database search (2004–2024) was supplemented by highly cited earlier works and authoritative monographs to introduce historical and methodological depth. The search term "heavy metals/ radionuclides and agricultural soils and phosphorus fertilizers" was used in English and Russian. The publications were sorted by date, selecting the first 250 relevant papers for 2020–2024, 100 for 2014–2020, and 50 for 2004–2014. The analysis suggests that mineral phosphorus fertilizers are an essential agrogenic source of ecotoxicants in agroecosystems, which may contain unregulated and, in some cases, high levels of HM and NOR, primarily cadmium (Cd) and arsenic (As). Long-term regular application can result in the gradual buildup of these elements and in the exceedance of safe levels in soils. Risk assessment should consider the phosphate rock origin, fertilizer type and norm of application, soil physicochemical properties, climate, crop biology, and agronomic practice, all of which influence contaminant bioavailability and transfer in the "crop–(livestock)–human" food chain. The results highlight the urgent need for comprehensive risk assessment schemes and stricter regulation of HM and NOR in fertilizers. Future research activities should focus on region-specific contamination pathways, innovative mitigation technologies, tightened fertilizer quality standards, and long-term environmental monitoring in support of food security, ecosystem stability, and sustainable agricultural production.