Research on Evaluating Nanomaterials for Chemical Safety
Manufactured nanomaterials are in more than 1,300 commercial products including medical equipment, textiles, fuel additives, cosmetics, plastics and more. EPA scientists research the most prevalent nanomaterials that may have human and environmental health implications. The research is developing a scientific foundation to better understand, predict and manage the challenges of nanomaterials.
- Why is EPA studying nanomaterials?
EPA researchers are studying the unique chemical and physical features of nanomaterials (such as size, shape, chemical composition, stability, etc) to help develop predictive models to determine which nanomaterials may pose a higher probability of risk and those expected to have little impact.
- What are the unique characteristics of nanomaterials?
Due to the rapid and diverse growth of engineered nanomaterials, it is a challenge for regulators and risk assessors to understand the potential for exposure and whether methods used for assessing conventional chemicals can be used for nanomaterials. EPA researchers are identifying and characterizing the unique chemical and physical features of nanomaterials, such as
- chemical composition,
- stability, etc.
This allows the researchers to develop predictive models to determine which nanomaterials may pose a higher probability of risk and those expected to have little impact.
- What nanomaterials is EPA studying?
- Nano Silver: Because silver nanomaterials have antibacterial, antifungal and antiviral properties, they 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 they interact 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.
- Cerium dioxide: Nanoscale cerium dioxide is used in electronics, plastics, biomedical supplies, energy, fuel additives, and other consumer products. One application of cerium dioxide nanomaterials leads to dispersion in the environment, which is the use as a fuel-borne catalyst in diesel engines. There is ongoing research to evaluate exposure to cerium dioxide from diesel emissions and the potential for environmental and public health impacts.
- Titanium dioxide: Nano titanium dioxide is used in many products. It can be found in sunscreens, cosmetics, paints and coatings, and electronic devices. Titanium dioxide may be activated by ultraviolet radiation, a normal component of sunlight, to catalyze reactions that can be toxic to fish and other aquatic species under certain conditions. EPA is researching the potential for titanium dioxide nanomaterials to be released from consumer products and enter the environment, be transformed in the environment, and to become toxic to sensitive environmental species or to humans.
- Iron: One important use of nano zero-valent iron particles is to catalyze the breakdown of chlorinated hydrocarbon compounds that are among the most common toxic contaminants found in hazardous waste sites. The injection of zerovalent iron into such sites is a relatively inexpensive and rapid way to reduce the presence of these hazardous environmental pollutants. EPA research is being conducted to assure that this beneficial use of nanomaterials is not associated with unwanted or unexpected adverse side effects on human health or the environment.
- Micronized Copper: Micro and nanometer sized copper particles are used as preservatives in pressure treated lumber and in some paints and coatings. Treated woods are produced by injecting finely ground copper carbonate -- or "micronized" particles -- into wood. EPA is working with the Consumer Product Safety Commission to evaluate the potential for release of copper particles or copper ions from such products under normal use and wear. Widespread use of copper-treated lumber has increased the potential for human and environmental exposure to these nanomaterials. This has created a need to better understand their fate and behavior. A team of EPA scientists measured how much micronized copper leaches from the copper-treated wood as it weathers and ages. The results were used to gage potential exposures from direct contact with the treated wood and its runoff. Another team of EPA scientists studied what happens to the copper particles when treated wood fragments are ingested. Sawdust from three copper-treated wood products were tested in a simulated digestion system consisting of an artificial stomach and intestinal fluid. Study results indicated that the copper escapes as copper ions when digested. This suggests that copper is highly bioaccessible at low pH and may pose a potential human exposure risk when ingested.
US EPA (2014) “Release of Micronized Copper Particles from Pressure-treated Wood Products.” (PDF) (56 pp, 1.3 M) Publication No. 600/R-14/365.
- How will EPA use this research?
EPA will use this research to develop research protocols for characterizing engineered nanomaterials (ENMs) and for evaluating exposure and toxicity in complex biological or environmental systems. This research will allow EPA scientists to evaluate the relationships between the physical and chemical properties of ENMs and their fate, transport, and effects which could lead to safer and more sustainable ENMs.
EPA develops scientific methods to study and evaluate the unique properties of nanomaterials, how they behave during manufacturing, product use, and end of life disposal. To better protect human health and the environment, EPA and others use the research to inform policy and regulatory decisions about chemicals.
- Mapping environmental fate of nanomaterials
- Nanomaterial effects on ecosystems and wildlife health
- Developing sustainable 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,
- exposure, and
- toxicity to humans and other species.
- Estimating Nanomaterial Transport in Soils
Quantifying how nanomaterials move from point of release to human or ecological systems is essential for assessing environmental exposures. Studies to quantify transport are time-consuming, labor-intensive, and can only be conducted on a small number of nanomaterials at a time.
EPA scientists evaluate the use of using an automated screening technology to help quantify transport. This technique can rapidly screen the mobility of nanomaterials. It also generates parameters for soil/sediments retaining nanomaterials and how nanomaterials are transported in soil/sediments. This methodology is useful to both regulators and the regulated community for the preparation of pre-manufactured notices that EPA requires.
- Innovative Nanomaterial Characterization Techniques
Measuring the concentration and size distribution of nanomaterials is critical for studying their environmental behavior. EPA researchers developed a unique technique to assess nanomaterials. The method combines a size separation technique with an elemental concentration detector to provide better assessments. The technique provides information simultaneously on nanomaterial size, number and metallic composition which was not possible with the older technique.
Using this technique, scientists can distinguish natural minerals or metal with natural organic matter from low concentrations of nanomaterials. This is critical for measuring nanomaterials in environmental samples such as drinking water and stream samples. This technique can be used by companies that produce nanomaterials to support premanufacture notice requirements. It is also useful to EPA's Office of Water our regional offices around the nations to monitor engineered nanomaterials in surface and ground water.
- Case Study: The Impact of Silver Nanoparticles on Municipal Solid Waste
EPA evaluated the possible environmental impacts of using polyvinylpyrrolidone (PVP) coated silver nanoparticles (PVP-AgNPs) for composting municipal solid waste. The analysis suggests that microbial activity can be impacted within hours of AgNPs exposure, although at low AgNPs concentrations activity can be relatively stable.
Data from this and other studies show that toxicity might be different when dealing with complex microbial communities. This suggests that data from pure culture studies may be inaccurate in predicting the impact of AgNPs on microbial communities.
It is unclear whether the bacterial response is caused by bacterial populations resistant to AgNPs, the decrease in Ag+ release, transformation of AgNPs, or reduction in bioavailability. More research is needed to identify which concentrations of silver nanoparticles begin to have a toxicological effect on waste management systems.
Nanomaterials have become widely used in products ranging from clothing (which incorporates bacteria-fighting nano Silver) to sunscreen. Nanomaterials are very useful, but there is insufficient information about how nanomaterials affect ecosystem health.
Since nanomaterials are much smaller than normal (about 100,000 times smaller than the width of a human hair), they are absorbed more easily by animal's lungs and skin. 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.
- Studying Nanomaterials in Ecosystems and the Environment
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.
- 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. Researchers used these to test over 50 samples. Metal nanoparticles show strong cellular stress responses across many different cell types. Most other nanomaterials are not significantly cytotoxic.
Nano forms of Cerium (Ce), Titanium Dioxide (TiO2), Silicon Dioxide (SiO2) and Carbon Nanotubes (CNT) are active in various primary human cell systems for a variety of endpoints, generally at concentrations above 1 g /ml. The methods demonstrate the feasibility of using these assays to evaluate a range of nanomaterials, but much refinement is needed before using them to identify any potential adverse health and environmental effects.
EPA scientists are researching more sustainable ways to produce and apply nonmaterials, in order to minimize their potential environmental and human health impacts.
- Green production of nanomaterials to promote sustainable nanotechnologies
EPA scientists evaluate the production of sustainable nanomaterials in a medium in which they are to be used. The approach EPA is evaluating can be used to replace hazardous chemicals with naturally occurring antioxidants that reduce the metal salts and contain the nanomaterials that are formed. Several protocols have been developed to show that the benign antioxidants present in agricultural wastes (e.g., grape must from wineries, beet juice, simple sugars, tea and coffee extracts) are good alternative starting materials to produce nanomaterials in water or by using nontoxic byproducts such as glycerol, which comes from the biofuel industry.
This research could provide safer methods to produce nanoparticles used for the growing nanotechnology industry. The impact of nanomaterials on health and the environment is further minimized by developing sustainable nanomaterials.
- Nano-encapsulated Membranes
Lack of safe drinking water is the primary cause of many diseases in the world today. Every day, tens of thousands of people die from causes directly related to contaminated water. The scarcity and contamination of worldwide drinking water requires the development of highly efficient water purification techniques such as membrane filtration. Membrane assisted water purification is found to be a solution for the water crisis. For instance, membrane purification technologies such as a Reverse Osmosis (RO), Membrane Distillation (MD) and recently Forward Osmosis (FO) are widely used to produce water from ground water, surface water, waste water, and water extracted from saline sources such as brackish ground water and seawater.
Nano composite membranes and materials are the backbone of various modern technologies for a variety of sustainable applications. EPA researchers are developing and evaluating a method to employ bio-renewable materials such as cellulose to develop nano-encapsulated membranes for future water purification purposes. EPA is developing novel methods for preparing cellulosic and nanomaterial incorporated cellulosic membranes for sustainable applications. The nano-encapsulated membranes currently being developed and tested by EPA researchers can be useful for a number of applications in water or solvent purification.
Collaborative Research on Nanomaterials
- Extramural Nanotechnology Research
- Duke University — Center for Environmental Implications of NanoTechnology
- University of California — Center for Environmental Implications of Nanotechnology (UC—CEIN)
- EPA and NSF Lifecycle and Molecular Design Grant Awards: Four groups of researchers hope to make the world safer via one-time sustainability science awards that the National Science Foundation (NSF) and the Environmental Protection Agency (EPA)
- EPA Partners for Nanomaterial Research
- Small Business Innovation Research (SBIR) Grants Awarded for Nanotechnology Projects
- National Nanotechnology Initiative (Nano.gov)
- Nanotechnology and Nanomaterials Fact Sheet (PDF) (2 pp, 269 K, About PDF)
- Nanomaterial Case Studies
- Nanotechnology Research Publications