Risk of Silver Transfer from Soil to the Food Chain Is Low after Long-Term (20 Years) Field Applications of Sewage Sludge

Summary

This field-based study examined the long-term fate of silver in agricultural soils amended with sewage sludge over two decades, evaluating the potential for silver transfer from both conventional industrial sources and emerging nano-silver applications into the terrestrial food chain. The findings indicate that despite chronic silver inputs via sewage sludge, the risk of significant silver transfer to food crops remains limited. This work contributes to understanding contaminant behaviour in amended soils and supports evidence-based risk assessment for biosolids recycling in agriculture.

UK applicability

Relevant to UK biosolids management policy, which permits sewage sludge application to agricultural land under Quality Protocol schemes. The findings provide long-term field evidence to support continued safe-use guidance, though UK soil and climate conditions should be considered alongside the study context.

Key measures

Silver concentrations in soil and food chain compartments following 20 years of sewage sludge field application

Outcomes reported

The study assessed the risk of silver (Ag) transfer from soil to the terrestrial food chain following long-term field applications of sewage sludge. The research measured silver accumulation and transfer pathways to determine whether Ag from traditional industry and nano-silver sources poses a food safety concern.

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