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November 11, 2015

Denmark Posts Several Publications Concerning Nanomaterials

Lynn L. Bergeson

On November 10, 2015, the Danish Environmental Protection Agency posted the following publications concerning nanomaterials:

  • Environmental assessment of nanomaterial use in Denmark: This is the concluding report of the project “Nanomaterials — occurrence and effects in the Danish environment” (NanoDEN). The projects in NanoDEN aimed to investigate and generate new environmentally relevant knowledge concerning nanomaterials on the Danish market and to assess the possible associated risks to the environment. The report summarizes the results from the sub-projects and assesses whether and how nanomaterials may pose a risk for the environment in Denmark. The assessment is based on investigations of nine selected nanomaterials that are expected to be environmentally relevant based on knowledge of consumption quantities, or how they are used: titanium dioxide; zinc oxide; silver; carbon nanotubes; copper oxide; zero valent iron; cerium dioxide; quantum dots; and carbon black.
  • Consumer risk assessment for nanoproducts on the Danish market: The report:
    • Assesses consumer risks associated with 20 selected consumer exposure/use scenarios;
    • Integrates the learnings from these assessments with findings from previous activities of the project;
    • Discusses and puts into perspective what we know about the overall exposure and risks for Danish consumers, also considering other sources of nanomaterials exposure; and
    • Identifies main gaps in knowledge and methodologies for assessing consumer exposure.
  • Dermal Absorption of Nanomaterials Titanium Dioxide and Zinc Oxide Based Sunscreen: Role of Size and Surface Coating: The conclusion states:

Based on our results using in vitro and in vivo mouse and human skin models we conclude that dermal penetration of TiO2 and ZnO NPs did not occur at or above the limit of detection of the used experimental methods. Should absorption of TiO2 and ZnO nanoparticles occur at levels below the detection limit of the assays used herein, the systemic dose would be very small (far lower than the doses used in the studies discussed above) and so highly unlikely to cause systemic toxicity based on toxicological evidence in rodents. This is in accordance with the conclusions that were made by the SCCS that stated that both kind of nanoparticles are safe to use for dermal applications up to a concentration of 25% in cosmetic products [SCCS (Scientific Committee on Consumer Safety), 2012; SCCS (Scientific Committee on Consumer Safety), 2014].

  • Environmental effects of engineered nanomaterials: Estimations of Predicted No-Effect Concentrations (PNECs): The report provides the following key findings:
    • Investigations have shown that currently accepted PNEC estimation approaches within the present European legislation in principle can be used for nanomaterials. This concerns the assessment factor (AF) and species sensitivity distribution (SSD) approaches. These methods do not take nano-specific processes during the testing of nanomaterials into account, and the tests may therefore not always be representative for natural conditions. Through a literature review carried out within the current project, three other methods were suggested: the probabilistic species sensitivity distribution (PSSD); the dissolved metal ion; and the indicative no effect concentration (INEC).
    • The current approach to select data for PNEC estimation favors effect studies conducted according to Good Laboratory Practice (GLP) and accepted guidelines. A consequence is that effect studies conducted according to guidelines for soluble chemicals may be unreliable as they do not take into account the specific nature of engineered nanomaterials (ENM).
    • Within the current project, an approach was developed for transparent evaluation of the suitability of effect studies to test ENMs and to what extent they are adequate for risk assessment. The approach focused on nano-specific parameters and highlights knowledge gaps and limitations in relation to data availability and relevance.
    • More than 1,200 scientific papers on effect studies of ENMs were found in the open literature. 500 of these revealed data on effects that potentially could be used for PNEC derivation. 50 percent of these studies used daphnia as the test organism, 30 percent used fish, and 20 percent used algae. Hardly any chronic studies were performed with fish. Nevertheless, no single study obtained the best score for risk assessment adequacy.
    • The number of sufficient effect studies adequate for risk assessment was, despite the large number of effect studies found, so low that PNEC estimation only could be made according to the AF approach.
    • Using the available data, silver nanoparticles were found to be the most toxic ENM (PNEC = 12 nanograms per liter (ng/L)), while titanium dioxide was found to be the least toxic (PNEC = 18 micrograms per liter (μg/L)). Due to a lack of adequate data it was not possible to derive PNEC values for carbon black and quantum dots; and
    • The derived PNEC values in this report were generally on the same level or slightly lower than the PNEC values found in the open literature or in the European Union’s Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) registrations. Compared with ion and bulk PNEC values in REACH registrations, the derived nano PNEC values in this report were in the same order of magnitude (silver) or one order of magnitude lower (titanium dioxide, zinc oxide, and copper oxide).