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Hazard assessment of a silver nanoparticle in soil applied via sewage sludge

 
: Schlich, Karsten; Klawonn, Thorsten; Terytze, K.; Hund-Rinke, K.

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Postprint (PDF; )

Environmental Sciences Europe : ESEU 25 (2013), Art.17
ISSN: 2190-4715
ISSN: 2190-4707
English
Journal Article, Electronic Publication
Fraunhofer IME ()
hazard assessment; silver nanoparticles; ecotoxicology; soil; sewage sludge

Abstract
Background: Silver nanoparticles (AgNPs) are widely used in many fields of application and consumer products due to their antibacterial properties. The aim of this study was to prepare a hazard assessment for one specific AgNP in soil, incorporated via sewage sludge (the sewage sludge pathway). The effects of pristine AgNPs on microorganisms, plants and earthworms were first determined in screening tests. Long-term tests over 140 days were then conducted with AgNPs added to soil via sewage sludge. AgNPs were incorporated into the sludge through a simulated sewage treatment plant (STP) over 10 days to allow transformation to occur and also by manual spiking over 2 h. The results of the most sensitive organism from the long-term tests, the soil microorganisms, are presented.
Results: The STP simulations confirmed that at environmentally relevant concentrations >90% of AgNPs remain bound to sewage sludge. Effects of AgNPs bound to sewage sludge and added to soil were similar to that of pristine NM-300K after degradation of the sludge. The predicted no-effect concentration for NM-300K in soil of 0.05 mg/kg dry soil determined a maximum threshold of 30 mg/kg dry sludge per application, considering the maximum addition of sewage sludge in Germany (5 tons per hectare every 3 years).
Conclusion: At environmentally relevant concentrations, AgNP absorption to sludge and aging in soil (even after transformation) cause toxic effects on soil microorganisms of the terrestrial ecosystem.

: http://publica.fraunhofer.de/documents/N-273849.html