[ARCHIVED] Nanotechnology: A Review of Exposure, Health Risks and Recent Regulatory Developments

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Nanotechnology is the creation of materials, devices, and systems by controlling matter at the nanometer scale (1-100 billionths of a meter). Potential exposures to engineered nanoparticles (ENPs) through contact with consumer products or air, water, and food sources are an emerging potential threat to human health. ENPs have unique properties and characteristics in addition to size, such as a high surface area-to-volume ratio and surface properties, which may increase their toxicity relative to bulk materials. Due to the high-volume production of consumer products containing ENPs, such as silver (Ag NP), carbon nanotubes (CNTs), titanium dioxide (TiO2 NP), and zinc oxide (ZnO NP), and the use of cerium oxide (CeO2 NP) in fuel, environmental exposure to these compounds is likely. Realistic exposure assessment is hampered by the paucity of knowledge regarding the source and fate of ENPs in the environment, and the lack of analytical methods capable of quantifying ENPs in environmental matrices; however, existing data regarding particulates and ultrafine particles, mineral fibres, and metal fumes may provide insights into potential risks of ENPs. There is no conclusive evidence linking exposure to ENPs from air, water, or food sources or from the use and disposal of consumer products to negative impacts on human health. Toxicology studies on animal models and animal and human cell lines are available and toxic effects have been identified; however, the relevance and implications of these findings for human populations are still not clear. Epidemiologic studies, with realistic exposures to ENPs, are lacking. Recent regulatory initiatives in Canada and elsewhere include developing: working definitions for nanomaterials, including their behaviour (e.g., aggregation/agglomeration); labelling requirements for products containing ENPs; collecting existing data and product information for current ENP manufacturers and users, as well as other testing; and addressing data gaps in the field of toxicology and exposure assessment. Research initiatives are underway in Canada and the United States to address knowledge gaps in the human exposure and health effects of ENPs. The scientific community is faced with the challenge of developing new risk assessment methodologies capable of identifying exposure characteristics and adverse health effects of ENPs.