Ranking initial environmental and human health risk resulting from environmentally relevant nanomaterials

Abstract

As nanomaterials find increased application in commercial and industrial products and processes so too the potential for release of these novel materials into the environment increases. The characteristics of these materials also may result in novel toxicological actions related to their nanoscale, which will have implications on their ecotoxicological and toxicological limits of exposure and eventual regulation. A framework for nanomaterial risk assessment on regulatory, ecotoxicological and toxicological bases developed from recent exposure and toxicity studies is presented. The release of nanoscale TiO(2), Ag and CeO(2) to the atmosphere and surface waters is assessed against provisional toxicological bench mark doses (BMDs) and critical effect doses (CEDs) developed from best available data. Predicted levels of nanomaterial release to surface waters and the atmosphere resulted in regulatory risk rankings of moderate concern based on worst case provisional regulatory limits. Inhalation and ingestion risk rankings were of very low concern based on the provisional inhalation and ingestion toxicity BMDLs and CEDLs determined for the nanomaterials in question. More toxicological data is needed on nanoscale CeO(2) inhalation to develop a true dose response as in vitro cytotoxicity studies yielded an inhalation risk ranking of lower concern. The moderate to high ecotoxicological risk rankings posed by the release of nanoscale TiO(2) and Ag to surface waters highlights the need for guidance and restriction on the usage and disposal of commercial products containing nanomaterial. The risk rankings presented in this assessment give a first indication of the relative risks posed by the usage and release of these materials into the environment and indicate what materials require further investigation into their nano-specific toxicological actions. As more nano-relevant toxicity studies are published, end-points and risk levels related to nano-specific toxicity actions may be determined and the provisional BMDLs developed as part of this framework refined, resulting in more confident risk rankings.

On the mechanism of nanoparticulate CeO2 toxicity to freshwater algae

“…Concentrations of CeO2 in surface waters such as in Ireland have been predicted to be in the sub-parts per billion (µg/L) range if 5-10% market penetration of CeO2 as a fuel catalyst were to be achieved (O'Brien and Cummins, 2010). This concentration is at least four orders of magnitude lower than the concentrations required for measurable toxicity to P. subcapitata in the current study and to the species Chlamydomonas reinhardtii, P. subcapitata, Daphnia magna and Thamnocephalus platyurus investigated in previous studies (Röyder et al, 2014;Van Hoecke et al, 2009).…”

Biological synthesis of metallic nanoparticles: plants, animals and microbial aspects

“…While pursuing the technical advantages of nano-dimension over bulk, one should be aware of the negative impacts of nano-sized materials. This issue has been well addressed by experts, and they have expressed their opinion toward possible solution [5][6][7][8][9][10][11][12][13][14][15][16][17]. Interestingly, nature responded to this issue in an unforeseen fashion.…”

Silver nanoparticle toxicity in Drosophila: size does matter

“…4 Because of these factors, a recent study labeled silver nanoparticle release into the environment a moderate to high ecotoxicological risk, about which we know very little. 7 Most of the current research examining nanoparticle toxicity uses in vitro methods that do not factor in the tendency of a particle to accumulate in tissues or be cleared from a whole organism. 8 The toxicity of a substance can be greatly affected by its propensity to accumulate in part of an organism, increasing the local concentration of the toxicant.…”