Determination of nanosilver dissolution kinetics and toxicity in an environmentally relevant aqueous medium

Harmon, Ashley R.; Kennedy, Alan J.; Poda, Aimee R.; Bednar, Anthony J.; Chappell, Mark A.; Steevens, Jeffery A.

doi:10.1002/etc.2616

Cited by 26 publications

(19 citation statements)

References 32 publications

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“…The higher toxicity of Ag NPs to algal cells was observed in acidic media (Oukarroum et al, 2014) and media with high ionic strength (Chambers et al, 2014), owing to the increased release of silver ions. However, the inverse phenomenon was reported in several studies where Ag NPs demonstrated decreased toxicity in media with higher ionic strength (Gao et al, 2009;Harmon et al, 2014). Mitigated bactericidal effects of ZnO NPs (Li et al, 2013) and TiO 2 NPs (Lin et al, 2014) were also observed in media with high pH or ionic strength.…”

Section: Introductionmentioning

confidence: 77%

Physicochemical transformation and algal toxicity of engineered nanoparticles in surface water samples

Zhang

Yang

et al. 2016

Environmental Pollution

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a b s t r a c tMost studies on the behavior and toxicity of engineered nanoparticles (NPs) have been conducted in artificial water with well-controlled conditions, which are dramatically different from natural waters with complex compositions. To better understand the fate and toxicity of NPs in the natural water environment, physicochemical transformations of four NPs (TiO 2 , ZnO, Ag, and carbon nanotubes (CNTs)) and their toxicities towards a unicellular green alga (Chlorella pyrenoidosa) in four fresh water and one seawater sample were investigated. Results indicated that water chemistry had profound effects on aggregation, dissolution, and algal toxicity of the NPs. The strongest homoaggregation of the NPs was associated with the highest ionic strength, but no obvious correlation was observed between the homoaggregation of NPs and pH or dissolved organic matter content of the water samples. The greatest dissolution of ZnO NPs also occurred in seawater with the highest ionic strength, while the dissolution of Ag NPs varied differently from ZnO NPs. The released Zn 2þ and especially Ag þ mainly accounted for the algal toxicity of ZnO and Ag NPs, respectively. The NP-cell heteroagglomeration occurred generally for CNTs and Ag NPs, which contributed to the observed nanotoxicity. However, there was no significant correlation between the observed nanotoxicity and the type of NP or the water chemistry. It was thus concluded that the physicochemical transformations and algal toxicities of NPs in the natural water samples were caused by the combined effects of complex water quality parameters rather than any single influencing factor alone. These results will increase our knowledge on the fate and effects of NPs in the aquatic environment.

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Section: Introductionmentioning

confidence: 77%

Physicochemical transformation and algal toxicity of engineered nanoparticles in surface water samples

Zhang

Yang

et al. 2016

Environmental Pollution

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“…Test media properties such as pH (El Badawy et al, 2010) and ionic strength (Harmon et al, 2014;Tejamaya et al, 2012) impact stability. Therefore, while standardized tests typically allow flexibility in selecting from multiple test media types ranging from very soft water to very hard water (e.g., OECD, 2012; USEPA, 2002a), such flexibility is problematic for acquiring consistent (repeatable) results from ENM hazard testing (Petersen et al, 2015).…”

Section: Test Media Modificationsmentioning

confidence: 99%

“…Similarly, Ma et al (2012) diluted EPA-MHRW fourfold and 100-fold in TiO 2 tests with Daphnia magna and Japanese Medaka, respectively, and pretested both species in the modified media to confirm organism health. Decisions to reduce the ionic strength of testing media for particle stability must also consider the environmental relevance and test organism health (Harmon et al, 2014) and comparison to historical databases for a test method (Petersen et al, 2015). If stability was improved in the modified media, that media is acceptable for use in bioassays.…”

Section: Test Media Modificationsmentioning

confidence: 99%

“…Dilution of MHRW to a lower conductivity (3 lS/cm) reduced agglomeration rates (Figure 2(F)); however, the dispersions were still unstable (>20% loss of material) at a more biologically acceptable conductivity of 100 lS/cm (Figure 2(F)). Since small improvements in stability at lower conductivities of 100 lS/cm (comparable to standard VSRW; USEPA, 2002a) this water was used for bioassays to accommodate organism health (Harmon et al, 2014).…”

Section: Materials Characterizationmentioning

confidence: 99%

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Assessing nanomaterial exposures in aquatic ecotoxicological testing: Framework and case studies based on dispersion and dissolution

Kennedy

Coleman

Diamond³

et al. 2017

Nanotoxicology

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The unique behavior of engineered nanomaterials (ENM) in aqueous media and dynamic changes in particle settling, agglomeration and dissolution rates is a challenge to the consistency, reliability and interpretation of standard aquatic hazard bioassay results. While the toxicological endpoints (e.g., survival, growth, reproduction, etc.) in ecotoxicity bioassays are largely applicable to ENMs, the standard methods as written for dissolved substances are confounded by the dynamic settling, agglomeration and dissolution of particulate ENMs during the bioassay. A testing framework was designed to serve as a starting point to identify approaches for the consistent conduct of aquatic hazard tests that account for the behavior of ENMs in test media and suitable data collection to support representative exposure metrology. The framework was demonstrated by conducting three case studies testing ENMs with functionally distinct characteristics and behaviors. Pretests with a temporal sampling of particle concentration, agglomeration and dissolution were conducted on each ENM in test media. Results indicated that a silver nanoparticle (AgNP) powder was not dispersible, a nano-TiO 2 powder was dispersible but unstable, and a polyvinylpyrrolidinone-coated AgNP was relatively stable in test media. Based on these functional results, Ceriodaphnia dubia bioassays were conducted to compare different exposure summary methods (nominal, arithmetic average, geometric average, time-weighted average) for calculating and expressing toxicity endpoints. Results indicated that while arithmetic means were effective for expressing the toxicity of more stable materials, time-weighted averaged concentrations were appropriate for the unstable nano-TiO 2 .ARTICLE HISTORY

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“…The present protocol utilizes the methods outlined in ISO 2000, , and Taurozzi 2013 for pre-dispersion of NP powder for stock generation. Aqueous NP stock generation, mixing, dilutions, and media spiking methods/ recommendations are leveraged from ISO 2000, Jiang et al 2009, Kennedy 2009, Kennedy 2010, Romer 2011, Taurozzi 2011, Kennedy 2012, Handy et al 2012, Tejamaya et al 2012, Harmon et al 2014.…”

Section: Introductionmentioning

confidence: 99%

Environmental Consequences of Nanotechnologies: Nanoparticle Dispersion in Aqueous Media: SOP-T-1

Coleman¹,

Kennedy²,

Harmon³

2015

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Homogenous dispersions of nanoparticles (NPs) for use in bioassay media for exposures/characterizations are a crucial need in ecotoxicology assays. The present protocol provides guidance and step-by-step methods for: (1) creating a working stock from nanoparticle powder and nanoparticle aqueous suspensions, (2) spiking working stock suspensions into aqueous bioassay media. The protocol also provides guidance on optimization of test media and organism health. Peer-reviewed publications and standards, with adaptations for aquatic bioassays are included. Users are directed to follow the protocol section relevant to their need and parent material (e.g. aqueous NPs or powder NPs). This protocol was developed on procedures created specifically for metal nanoparticles, but may have broader application. In an effort to validate procedural consistency, values associated with reference materials (RM) are included. The standard references include powderbased and aqueous suspensions from the National Institute of Standards and Technology (NIST) and NanoComposix (NC); including aqueous suspension of NIST Reference Material citrate coated 30 nm Au and NC citrate coated 30 nm Ag, and powdered NIST standard reference material 1898 TiO2 nanomaterial. The Ag and Au reference materials were selected to represent moderately soluble and relatively insoluble materials, respectively. If followed correctly, near-homogenous particle dispersions of the reference materials and a best case scenario for dispersion of test materials in aqueous media should be generated based on best procedural guidance available.

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Determination of nanosilver dissolution kinetics and toxicity in an environmentally relevant aqueous medium

Cited by 26 publications

References 32 publications

Physicochemical transformation and algal toxicity of engineered nanoparticles in surface water samples

Physicochemical transformation and algal toxicity of engineered nanoparticles in surface water samples

Assessing nanomaterial exposures in aquatic ecotoxicological testing: Framework and case studies based on dispersion and dissolution

Environmental Consequences of Nanotechnologies: Nanoparticle Dispersion in Aqueous Media: SOP-T-1

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