Research on Nanomaterials

On this page:

• What are nanomaterials? 
• What are some nanomaterials that EPA researchers are studying?
• How will EPA use this research?
• Nanomaterial Effects on Ecosystems and Wildlife Health
• Additional Resources

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What are nanomaterials?

Nanomaterials are partially characterized by their tiny particle size, measured in nanometers. A nanometer is one millionth of a millimeter or approximately 100,000 times smaller than the thickness of a sheet of paper. Materials manufactured to such a small scale are referred to as engineered nanomaterials (ENM). Increasingly, ENMs are being used in consumer and commercial products, including personal care products, cosmetics, fabrics, treated woods, paints, medical equipment, fuel additives, plastics and more.

Why is EPA studying nanomaterials?

Due to the rapid and diverse growth of engineered nanomaterials, it is difficult for regulators and risk assessors to understand the potential for exposure to nanomaterials and whether methods used for assessing risk of conventional chemicals can be used for nanomaterials. EPA research is developing a scientific foundation to better understand, predict and manage the challenges of nanomaterials.

EPA’s research is focused on characterizing the occurrence of nanomaterials, examining the transport and fate of nanomaterials in the environment, and estimating exposure to humans. This research is coordinated with partners across the federal government through the National Nanotechnology Initiative.  

What are the unique characteristics of nanomaterials?

EPA researchers are identifying and characterizing the unique chemical and physical features of nanomaterials, such as:

• size
• shape
• chemical composition
• stability, etc.

This allows the researchers to develop predictive models to determine which nanomaterials may pose a higher probability of risk to human health and the environment and those expected to have little impact.

Mapping environmental fate of nanomaterials

The environmental fate of chemicals describes the processes by which chemicals move and change in the environment. Due to the uncertainty about the unique characteristics of nanomaterials and their potential uses and effects, it is important to map the environmental fate of nanomaterials. EPA is developing information to describe the relationships between key properties of nanomaterials and their:

• environmental fate
• transport
• transformation
• reactivity
• bio-distribution
• exposure
• toxicity to humans and other species

What are some nanomaterials that EPA researchers are studying?

Nanosilver

Silver nanomaterials have antibacterial, antifungal and antiviral properties and are used in medical equipment, textiles and cosmetics, fabrics, plastics and other consumer products. EPA is researching the fate and transport of nanosilver and how it interacts with the environment. EPA is developing methods to measure nanosilver concentration and characteristics such as size, shape, surface charge, and surface chemistry to better understand the role of these physical and chemical properties.

Carbon Nanotubes

These nanomaterials are one of the most abundant classes of nanomaterials and come in a variety of shapes and sizes. Carbon materials have a wide range of uses, including composites for vehicles or sports equipment, coatings, textiles, polymers, plastics and integrated circuits for electronic components. The interactions between carbon nanotubes and natural organic matter strongly affect their transport, transformation and exposure in aquatic environments. EPA research evaluates the physical and chemical properties of carbon nanotubes to determine which ones influence their behavior in the environment and in biological systems.

3D Printer Emissions

The growth of the 3-D printing industry will facilitate an expanding number of printers entering the industrial and consumer markets. These low-cost 3D printers are increasingly being used in residential, small business, and educational environments to create unique, physical 3D objects from digital models. EPA research has shown that 3-D printing produces ultrafine particles at harmful concentrations for sensitive populations, such as children, and that emission chemistry and particle concentration are dependent on the types of filaments used in the printing process. The use of nanomaterials in, and generation of incidental nanoparticles from 3-D printing is an emerging exposure issue. Our researchers plan to continue their studies in hopes of limiting exposure concerns to 3D printer users. Learn more:  

Learn more about EPA’s 3D printing research.

Quantum Dots

These nanomaterials are the second most common engineered nanoparticle submitted under the Toxic Substances Control Act. Quantum dots are semiconductor nanocrystals that can be composed of metals and metalloids, with some properties like metals. Examples include copper, lead, arsenic, and selenium. Quantum dots are well suited to a wide array of consumer, industrial, and medical products, as well as applications like biomedical imaging, targeted gene and drug delivery, solid state lighting, and solar cells. EPA is investigating questions about the potential for exposure and specific data gaps surrounding quantum dots.

Nano-pesticides

EPA is investigating the environmental fate and transport of commercially available nano-enabled pesticides. Pesticides that are regulated by Federal Insecticide, Fungicide, and Rodenticide Act can contain nanomaterials as active ingredients or as carriers, the primary material used to allow a pesticide to be dispersed effectively. Examples include metals, metal oxides, nano-silica, and carbon nanostructures. These nanomaterials are ultimately released to the environment (soil, sediments, and water) after use and may undergo transformation - including changes to form and chemical structure - and reaction to form other nanomaterials. Changes to basic properties of nanomaterials (e.g., size, shape, oxidation state, and partitioning) can have significant effects on their uptake by plants, transport in the environment, and biomarkers of ecological exposure.

How will EPA use this research?

As EPA develops scientific methods to study and evaluate the unique properties of nanomaterials, how they behave during manufacturing and product use, and end of life disposal, EPA and others will use the research to inform policy and regulatory decisions about chemicals to better protect human health and the environment.

Innovative Nanomaterial Characterization Techniques

Measuring the concentration and size distribution of nanomaterials is critical for studying their environmental behavior, so EPA researchers developed a unique technique to assess nanomaterials. The method combines a size separation technique that provides better assessments to help develop predictive models of exposure. This method develops protocols for characterizing nanomaterials and for evaluating exposure and toxicity. Using this technique, scientists can distinguish natural minerals or metal from nanomaterials. This is critical for measuring nanomaterials in environmental samples such as drinking water and stream samples. Recently, EPA scientists have been working to develop models that predict the transport of nanomaterials through aquatic environments. These models have been incorporated into EPA’s existing water quality modeling software package, Water Quality Analysis Simulation Program (WASP). The current focus of model development is on semiconductor nanostructure quantum dots. Quantum dots have an increasing usefulness in electronics and medicine due to their semiconductor properties, but often contain heavy metals such as cadmium, which is a known toxicant.

Using New Chemical Data to Classify Nanomaterials

EPA scientists are using new high-throughput screening and zebrafish assays (from the ToxCast chemical prioritization research) to determine if they can be used to screen nanomaterials for potential effects to human health and the environment. For example, EPA scientists have found that metal nanoparticles show strong cellular stress responses across many different cell types while most other nanomaterials are not significantly cytotoxic.

Learn more: EPA’s ToxCast Chemical Screening Program

Nanomaterial Effects on Ecosystems and Wildlife Health

Studying Nanomaterials in Ecosystems and the Environment

Nanomaterials have become widely used in products ranging from clothing (which incorporates bacteria-fighting nanosilver) to sunscreen. Nanomaterials are very useful, but there is insufficient information about how nanomaterials affect ecosystem health. EPA is in the process of researching how nanomaterials interact with biological processes important to the health of ecosystems and wildlife species that live in these ecosystems. Evaluating the potential toxicity of nanomaterials is difficult because they have unique chemical properties, high reactivity, and do not dissolve in liquid media. Testing for potential impacts on ecological systems is especially challenging because they enter the environment through multiple exposure routes, transform over time, and food-chain transfers occur.

Existing test protocols for soluble chemicals may not work to test the safety of nanomaterials. EPA researchers conduct laboratory analyses to evaluate new approaches and procedures for studying the impacts of specific nanomaterials in freshwater, marine and terrestrial ecosystems. The results from the lab studies provide guidance about how to properly evaluate nanomaterials and how to characterize them in key organisms and different ecosystems.

Other Nanomaterial Research

NaKnowBase

A substantial amount of research has been published on the topic of nanomaterials, but the information is difficult to assimilate and harmonize. NaKnowBase, a relational database with data collected from peer reviewed articles, is being developed to relate the properties of nanomaterials with their harmful effects. NaKnowBase includes intrinsic and extrinsic physical and chemical nanomaterial parameters, functional assay designations, a range of outcome variables and meta-data linked to ORD research and quality assurance plans. The database, depending on the development of the necessary tools, may be used by EPA program offices to inform regulatory decisions around nanomaterials. Learn more: View NaKnowBase chemicals.

Collaborative Research on Nanomaterials

In 2011, the US EPA began a long-term partnership with the US Consumer Product Safety Commission (CPSC) to evaluate potential human exposure of nanomaterials used in consumer products. The focus of this research collaboration has been on quantifying the release and transformation of nanomaterials, and potential exposure of consumers. The research effort began with a focus on nano copper materials used in pressure treated lumber, and expanded to include surface coatings, and the interaction and impact of utilizing two or more nano-enabled products together.

Currently, EPA is working in conjunction with CPSC and the National Institute for Occupational Safety and Health (NIOSH) to quantify the release of volatile organic compounds (VOC) and aerosols released during 3D printing. The goal of the research is to develop a baseline data set for aerosol emissions and to identify key characteristics of raw materials that may produce large volumes of particulates or harmful VOC compounds. Additionally, both agencies are focused on determining if the aerosols or chemicals released from printed objects will have an adverse impact on children's health.

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Learn More:

• Control of Nanoscale Materials under the Toxic Substances Control Act
• National Nanotechnology Initiative (Nano.gov)
• Duke University — Center for Environmental Implications of NanoTechnology
• EPA Partners for Nanomaterial Research

Publications:

• Nanomaterials Research Publications