Researchers Study Nanomaterials On the Move
With the use of nanotechnology in the consumer and industrial sectors expected to increase significantly in the future, it is necessary to understand what happens to nanomaterials when they are accidentally or intentionally released into the environment.
This fate and transport science is important to ensure that, as nanomaterials are developed and used, unintended consequences of exposures to humans and ecosystems are prevented or minimized.
How nanomaterials move after being released into the environment and where they go are only beginning to be understood. Knowledge of how these materials work, how they age, and how they interact with other compounds and with each other is limited.
Research conducted in the U.S. Environmental Protection Agency is providing a fundamental understanding of the physical and chemical properties of nanomaterials. This information can then be used to determine how nanomaterials may transform, and where they may be transported if they are released to the environment. EPA researchers are working to address the following questions:
- What are the major processes and properties that govern the environmental fate and transport of engineered nanomaterials?
- How are these processes and properties related to the physical and chemical properties of these nanomaterials?
- Develop a scientific understanding of the processes that govern the fate and transport of manufactured nanomaterials
- Measure the chemical and physical properties of manufactured nanomaterials and determine how these properties influence fate and transport
- Identify the exposure pathways associated with production, end-use, and recycling or disposal of manufactured nanomaterials in different settings
- Improve the scientific understanding of detection methodologies for quantifying manufactured nanomaterials
- Develop multiple predictive models for understanding and measuring the fate and transport of manufactured nanomaterials
Initially, scientists are studying how to detect nanomaterials in the environment, and then how to identify and describe them. This work includes the development and application of analytical methods.
Detecting and then characterizing nanomaterials will allow scientists to discern the extent to which they are transported, and whether they are transformed by environmental interactions.
Scientists can then apply this information to develop models that predict environmental fate and transport of these materials, and estimate potential human and ecological exposures.
Scientists are evaluating EPA's current fate and transport and exposure models for their applicability to nanomaterials. For soil, sediment, and groundwater, they are coupling the model evaluation with the development of a model-scale system to simulate the transport of nanomaterials deposited in surface water under different flow conditions. Researchers will then monitor and characterize what happens to the nanomaterials.
The data will be used to modify current surface water models to predict nanomaterial movement.
Current research suggests that inhalation may be the most important exposure pathway for causing adverse affects in people. This pathway is of particular concern for emissions from both mobile and stationary sources.
EPA is conducting research to determine the mobility, atmospheric reactions, and deposition of nanomaterials that are released to the atmosphere. The research began with evaluation of the nano-scale form of the diesel fuel additive cerium oxide.
The cerium oxide research will model the transport from emission point to deposition and identify the potential for nanomaterial availability for inhalation exposure.
Scientists will extend this characterization and modeling research to titanium dioxide and nano-silver, and evaluate fugitive emissions from stationary sources – those emissions that are not released through a stack, vent or other confined air stream.
Scientists will also evaluate regional- and local-scale atmospheric models and begin modifying those models (or developing new models) to accommodate nanoscale particulates.
Application and Impact:
The results from EPA's research are improving our understanding of the environmental fate and transport of manufactured nanomaterials. This will allow EPA to develop a set of predictive tools that can be used to determine the potential impacts from releases of nanomaterials into the environment.
Ross Highsmith (firstname.lastname@example.org), National Exposure Research Laboratory, EPA's Office of Research and Development, 919-541-7828.