Nanomaterials for environmental studies: Classification, reference material issues, and strategies for physico-chemical characterisation

114

Abstract-The recent emergence of manufactured nanoparticles (NPs) that are released into the environment and lead to exposure in organisms has accelerated the need to determine NP toxicity. Techniques for measuring the toxicity of NPs (nanotoxicology) in ecological receptors (nanoecotoxicology) are in their infancy, however, and establishing standardized ecotoxicity tests for NPs are presently limited by several factors. These factors include the extent of NP characterization necessary (or possible) before, during, and after toxicity tests such that toxic effects can be related to physicochemical characteristics of NPs; determining uptake and distribution of NPs within exposed organisms (does uptake occur or are effects exerted at organism surfaces?); and determining the appropriate types of controls to incorporate into ecotoxicity tests with NPs. In this review, the authors focus on the important elements of measuring the ecotoxicity of carbon NPs (CNPs) and make recommendations for ecotoxicology testing that should enable more rigorous interpretations of collected data and interlaboratory comparisons. This review is intended to serve as a next step toward developing standardized tests that can be incorporated into a regulatory framework for CNPs. Environ. Toxicol. Chem.

Section: Steps In Conducting Ecotoxicity Tests With Cnpsmentioning

confidence: 99%

Methodological considerations for testing the ecotoxicity of carbon nanotubes and fullerenes: Review

Petersen

Henry

2011

114

“…These generic issues can present practical problems, such as how to clean and prepare test vessels, but they also can represent issues of fundamental scientific importance, such as experimental design and the use of controls. The scientific issue around experimental design, including the use of reference ENMs, particle size controls, whether to use dispersing agents, and so forth, have been discussed extensively [5,11,12]. The present study focuses on the practical aspects of deciding what to do and how to do it.…”

Section: Generic Issues In Test Methodologymentioning

confidence: 99%

“…The minimum characterization requirements for stock solutions of ENMs have been discussed at length, with agreement that stock solutions can be verified [5,11], but less consideration has been given to practical measurement during an ecotoxicity test. A consensus view from the scientific community on what dose metric should be used routinely in ecotoxicity testing is still forming, and collecting a sufficient weight of evidence for or against using a particular dose metric (such as particle size, particle number, or mass concentration) in a regulatory test will take some years, and it may be specific for some types of ENMs.…”

Section: Characterization Of the Test Media During Experimentsmentioning

confidence: 99%

Ecotoxicity test methods for engineered nanomaterials: Practical experiences and recommendations from the bench

Handy

Cornelis

Fernandes

et al. 2011

302

236

Abstract-Ecotoxicology research is using many methods for engineered nanomaterials (ENMs), but the collective experience from researchers has not been documented. This paper reports the practical issues for working with ENMs and suggests nano-specific modifications to protocols. The review considers generic practical issues, as well as specific issues for aquatic tests, marine grazers, soil organisms, and bioaccumulation studies. Current procedures for cleaning glassware are adequate, but electrodes are problematic. The maintenance of exposure concentration is challenging, but can be achieved with some ENMs. The need to characterize the media during experiments is identified, but rapid analytical methods are not available to do this. The use of sonication and natural/synthetic dispersants are discussed. Nano-specific biological endpoints may be developed for a tiered monitoring scheme to diagnose ENM exposure or effect. A case study of the algal growth test highlights many small deviations in current regulatory test protocols that are allowed (shaking, lighting, mixing methods), but these should be standardized for ENMs. Invertebrate (Daphnia) tests should account for mechanical toxicity of ENMs. Fish tests should consider semistatic exposure to minimize wastewater and animal husbandry. The inclusion of a benthic test is recommended for the base set of ecotoxicity tests with ENMs. The sensitivity of soil tests needs to be increased for ENMs and shortened for logistics reasons; improvements include using Caenorhabditis elegans, aquatic media, and metabolism endpoints in the plant growth tests. The existing bioaccumulation tests are conceptually flawed and require considerable modification, or a new test, to work for ENMs. Overall, most methodologies need some amendments, and recommendations are made to assist researchers. Environ. Toxicol. Chem. 2012;31:15-31. # 2011 SETAC

“…Stone and co-workers [35] have suggested that the main NP properties that should be evaluated in ecotoxicological studies to describe exposure are dispersability, agglomeration/aggregation, dissolution rate, size, surface area and charge, and surface chemistry. These properties are likely to be key in controlling NP stability, and consequently on their transport through the environment and availability to organisms.…”

Section: Behavior Of Metal-based Nps In Soilmentioning

confidence: 99%

Metal‐based nanoparticles in soil: Fate, behavior, and effects on soil invertebrates

Tourinho

Gestel²,

Lofts

et al. 2012

401

229

Abstract-Metal-based nanoparticles (NPs) (e.g., silver, zinc oxide, titanium dioxide, iron oxide) are being widely used in the nanotechnology industry. Because of the release of particles from NP-containing products, it is likely that NPs will enter the soil compartment, especially through land application of sewage sludge derived from wastewater treatment. This review presents an overview of the literature dealing with the fate and effects of metal-based NPs in soil. In the environment, the characteristics of NPs (e.g., size, shape, surface charge) and soil (e.g., pH, ionic strength, organic matter, and clay content) will affect physical and chemical processes, resulting in NP dissolution, agglomeration, and aggregation. The behavior of NPs in soil will control their mobility and their bioavailability to soil organisms. Consequently, exposure characterization in ecotoxicological studies should obtain as much information as possible about dissolution, agglomeration, and aggregation processes. Comparing existing studies is a challenging task, because no standards exist for toxicity tests with NPs. In many cases, the reporting of associated characterization data is sparse, or missing, making it impossible to interpret and explain observed differences in results among studies. Environ. Toxicol. Chem.