Y. Zhang, C. L. Lemieux, M. Zein Aghaij, D. Vladisavljevic, M. Hill
Keywords: manufactured nanomaterials, risk assessment, prioritization, consumer exposure, models
Summary:Given the ever increasing use of manufactured nanomaterials (MNMs) worldwide, Health Canada and Environment and Climate Change Canada have undertaken an initiative to prioritize and assess nanomaterials in commerce in Canada for risk to human health and the environment. This presentation will showcase the approach and results of prioritization and introduce available tools for assessing consumer exposure to MNMs. Information submitted pursuant to a mandatory survey under section 71 of the Canadian Environmental Protection Act identified over 50 nanomaterials as being in commerce in Canada. Based on information on production/import volume, uses, hazard, as well as consideration of physical-chemical properties, a prioritization exercise was conducted. Nanomaterials were identified as being of low, moderate or high priority for assessment. Some nanomaterials could not be prioritized due to a lack of hazard information, and have been identified as research priorities for further information gathering activities. Through the prioritization exercise, over 95% of the MNMs were found to be used in consumer applications including cosmetics and personal care products, pharmaceutical products, food and beverages, household cleaning products, paints and coatings, adhesives and sealants, toys, paper products, etc. It is critical to understand and assess any potential human health risks that may result from direct exposure to consumer products containing these MNMs. To the best of our knowledge, information on MNMs from consumer products (e.g., release, migration/leaching from product matrix) is scarce, and development of appropriate measurement techniques for MNMs is still ongoing. Under the auspices of the OECD’s Working Party of Manufactured Nanomaterials, Canada is leading an initiative to identify and assess the applicability of exposure models for use in characterizing consumer exposure to MNMs. An overview of available models will be presented, with a focus on exposure to MNMs resulting from their use in consumer products; factors examined include platform availability, applicability domain, required input parameters, and the extent of validation and assumptions. The models were grouped into 3 categories: control banding, nano-specific, and exposure models for bulk chemicals that may be adjusted for nanomaterials. In addition, a descriptive list of databases specifically for MNMs or products containing MNMs will be provided. Uncertainties and challenges encountered within the context of regulatory risk assessment will be discussed. Next steps include the development of a MNM risk assessment framework under the Canadian regulatory context, as well as evaluation of the suitability of the consumer exposure models for assessing MNMs (i.e., examination of model assumptions, limitations and uncertainties). Research and information-gathering strategies will also be developed in order to fill data gaps identified at the prioritization stage. A systematic evaluation of the risks posed by in-commerce MNMs will ensure that the risks of these nanomaterials are appropriately managed in Canada, protecting the health of Canadians.