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An Evaluation of Ecotoxicity Test Guidelines: Their Adequacy for Nanomaterials
Citation:
DIAMOND, S. A., C. P. ANDERSEN, S. HIRANO, M. G. JOHNSON, D. R. MOUNT, P. PANDARD, P. RYGLIZEISKI, J. J. SCOTT-FORDSMAND, AND K. STEWART. An Evaluation of Ecotoxicity Test Guidelines: Their Adequacy for Nanomaterials. Presented at SETAC Annual Meeting, Tampa, FL, November 16 - 20, 2008.
Impact/Purpose:
Impact Statement: Nanotechnology is an emerging field that will produce hundreds of new and novel substances that will require regulatory toxicity testing. The international scientific community is focused on determining how such testing will be conducted. The review that will be presented summarizes the adequacy of existing international test methods and contributes to the understanding of problems associated with the estimation of nanomaterials ecotoxicity.
Description:
Advances in nanotechnology are resulting in the production of new nanomaterials at a rapid pace. Driving the dramatic development of new materials and products is the prospect of stronger and lighter materials, better and more efficient energy systems, potential tremendous benefits to medicine, and prospects for other substantial technological advances. At the same time, due to their nano-scale size and novel structures or forms, little is known about their potential toxicological hazard or ecological risk. As with traditional potential stressors, many nanomaterials will be regulated based on the results of standardized toxicological tests. However, the adequacy of existing guidelines for testing these unique materials is undetermined. To address this and other issues associated with nanotechnology, the Organization for Economic and Cooperative Development (OECD) has formed the Working Party on Manufactured Materials (WPMN). The WPMN convened an international panel of experts to review OECD ecological test guidelines for their adequacy in assessing the hazard of nanomaterials. The review included 25 OECD harmonized test guidelines, an OECD document describing testing "difficult substances," and a few selected Environment Canada and ISO test guidelines. Each test guideline was reviewed by at least one workgroup member with expertise in the specific media and/or organisms used in testing. In brief, the compilation and summary of these reviews indicated that all existing test guidelines are deficient in their description of preparation of nanomaterials exposure media, characterization of nanomaterials prior to, and after, their incorporation into media, and guidance on many aspects of metrology of nanomaterials and exposure. A critical deficiency in current test guidelines is guidance on quantification of exposure-response relationships. In essentially all cases, deficiencies were related to the particulate or fibrous nature of nanomaterial, and the fact that exposures in liquid media will be via colloidal dispersions rather than solutions. A specific area where current test guidelines seem adequate for nanomaterials include described endpoints; there is little reason to expect that endpoints such as growth, reproduction, and mortality shouldn't reflect harmful effects of nanomaterials. However, additional endpoints specific to nanomaterials might be suggested by research results. These and other aspects of the OECD review process will be discussed relative to toxicological issues associated with regulatory testing of nanomaterials. This abstract does not necessarily reflect USEPA policy.