### MEMORANDUM

TO: William Swietlik, U.S. EPA/EAD

FROM: Eva Knoth, ERG Kim Wagoner, ERG

DATE: January 23 , 201 5

SUBJECT: Engineered Nanomaterials in Industrial Wastewater: Literature Review and Implications for 304 m

1. B ACKGROUND
As required by Section 304 ( m ) of the Clean Water Act, EPA annually reviews industrial discharges to identify new industries requiring regulation or existing regulations that may need to be revised

. In odd

- numbered years, EPA reviews the established effluent limitations guidelines and standards ( ELGs ) used to regulate wastewater discharges from 58 point source categories. In

even

- numbered years, EPA uses additional data sources to expand its ability to iden tify new pollutants of concern or wastewater streams in industrial categories not currently regulated by ELGs.

As part of the 2014 A nnual R eview, EPA is investigat ing engineered nanomaterials (ENMs) , a potential emerging industrial wastewater pollutant category. ENMs are manmade material s comp o sed of primary particles with sizes on the order of 1 to 100 nanometers ( nm ) in at least one dimension that exhibit properties that are not found in bulk samples of the same material ( U.S. EPA, 2011a )

. Nanotechnology is a rapidly advancing field of research and

commerce and offers potential benefits for health, consumer products, and electronics applications. According to the Nanotechnology Consumer Product Inventory

, ENM s are currently used in over 800 consumer products in the U.S. ( Project on Emerging Na notechnologies, 2014 ) . However , the environmental and human health risks associated with these materials are largely unknown

. Recent research presented at the Society of Environmental Toxicology and Chemistry ( SETAC ) North America 33 rd Annual Meeting i n November 2012 indicates that ENMs may impact human health and the environment

. Although researchers have conducted little dir ect sampling and analysis of industrial wastewater discharges, they have identified industrial discharges as a possible route for ENM s to enter the environment ( Gottschalk & Nowack, 2011 ; Hendren et al., 2011 ; Musee, 2011 )

. I n its Final 2010 Effluent Guidelines Program Plan , EPA solicited data and information for future annual reviews on the manufacture, use, and environmental release of silver materials, including nanosilver

, due to their anti

- microbial activi ty and potential to create a source of silver in associated industrial wastewater discharges ( U.S. EPA, 2011c )

. Several commenters indicated that EPA should investigate the impact of nanosilver ; a few in particular indicated that EPA should investigate all nanomaterials ( U.S. EPA, 2013d )

.Memorandum January 23, 2015 Page 2

Several of EPA’s Offices are currently assessing ENMs for their potential effects on human health and the environment

, through research into chemical safety, characterization techniques, and life cycle assessment and risk assessment of these ENM s in air, water

, and soil ( U.S. EPA, 2013b )

. Table 1 lists the types of ENM s the Agency is currently assessing and common applicat ions for their use.

Source: (U.S. EPA, 2013b )

. In response to the recent interest, research, and concerns raised in comments , ERG was tasked with reviewing and summarizing current literature about the fate and effects of ENM s on the environment and human health and about the presence and discharge of ENMs in industrial
wastewater

.

T his memorandum describes ERG ’ s literature review and presents a brief overview of nanomaterials, production methods

, and p otential waste streams , as well as the status of research into the ir environmental fate and toxicity. It also describes the status and availability of analytical methods and tools to measure, quantify

, and characterize nanomaterials in industrial
wastewater

. Lastly, it summarizes the existing d ata gaps a nd areas of research that are needed to fully assess the risk and impact of ENM s and inform future decisions regarding their discharge in industrial wastewater s

. Based on the recommendation of several leading researchers, ERG ’s review of current research focused on the production, environmental release, fate

, and toxicity of three classes of ENMs : silver, titanium dioxide

, and carbon

- based nanomaterials ( Hochella, 2013 ; Wiesner, 2013 )

. These three classes of ENMs are estimated to be produced in the largest volumes and are commonly used in commercial an d consumer products

. In addition, research has more fully classified their impact on human health and the environment than the impacts of other types of ENMs ( for which there is little information )

.

R esearch on the environmental health and safety of ENM s is rapidly progressing and many efforts are underway to advance the field. This memorandum highlights information identified through December 2013 , as described in Section 2.0

.

2. L ITERATURE R EVIEW AND R ESEARCH M ETHODOLOGY

To assess information available a nd support EPA’s evaluation of potential industrial wastewater discharges and associated risks of discharged ENM s, ERG ’s investigation focused

on : Table 1 . Engineered Nanomaterials Currently Being Assessed by EPA and Their Common Applications

Engineered Nanomaterial Common Applications Carbon nanotubes Electronics, advanced materials, biomedical applications Cerium oxide Electronics, energy, fuel additives, biomedical supplies TiO 2 Paints and coatings, cosmetics, semiconductors, water treatment and remediation Silver Textiles, cosmetics, biomedical supplies Iron Optics, water treatment

, and remediation Micronized copper Wood preservativeMemorandum January 23, 2015 Page 3

• Production methods and potential aqueous waste streams from manufacturing and processing ENM s

.

• Fate, transport, and p otential effects of nanomaterials on hum an health and the environment

.

• A nalytical techniques available to detect nanomat erials in industrial wastewater

.

• P resence of nanomat erials in industrial wastewater

.

• Treatment technologies to remove na nomat erials from wastewater.

SETAC ’s 2012 conference proceedings included over 125 presentations and posters about nanomaterial

- related research , which primarily focused on fate and transport, toxicity

, and analytical techniques ( SETAC, 2012 )

. ERG reviewed this nanomaterial

- related research and catalogued relevant abstracts as a starting point for further research.

N ext, ERG identified (partly through the SETAC abstracts) principal government and university researchers and organizations that focus on studying the environmental impact s of ENM s

. ERG identified additional stakeholder s based on nanomaterials

- related research conducted by several EPA offices including the Office of Pollution Prevention and Toxics (OPPT) and the Office of Research and Development (ORD) National Exposure Research Laboratory (NERL) . Concurrently, the EAD WAM identified and reached out to key researchers and stakeholders involved in nanomaterial research within the A gency.
ERG developed a list of questions (approved in advance by the E AD WAM) to discuss with each of the contacts. ER G and the EAD WAM used the list to direct the discussion toward answering EPA’s outstanding questions and to ident ify additional resources to further its understanding of the presence and potential impact of ENM s in industrial wastewater

. A copy of the questions is provided in Appendix A for reference.

Using the contacts identified in the initial reviews , ERG corres ponded with two leading researchers in March 2013 :

• Mark Wiesner, James L. Meriam Professor, Department of Civil and Environmental Engineering, Duke University ; Director of the Center for the Environmental Implications of Nanotechnology ( CEINT )

.

• Michael Hochella Jr., University Distinguished Professor , Department of Geosciences, Virginia Tech ; member of CEINT

.
ERG also communicated by email with:

• Paul Westerhoff, Professor, School of Sustainable Engineering and t he Built Environment, Associate Dean for Research and Graduate Affairs, Ira A. Fulton Schools of Engineering, Arizona State University

.Memorandum January 23, 2015 Page 4

• Suzanne Davis, Hazardous Substances Engineer, California Department of Toxic Substances Control

.
The EAD WAM communicated with the following EPA and federal age ncy colleagues between March and June 2013:

• David Meyer, Chemical Engineer, EPA ORD National Risk Management Research Laboratory ( NRMRL )

, Sustainable Technologies Division

.

• Thabet Tolaym a t, Environmental Engineer, EPA ORD NRMRL

.

• Katrina Varner, Research Chemist, EPA ORD NE RL

– L as Vegas/Environmental Sciences Division/Environmental Chemistry Branch

.

• Steve Diamond, EPA National Health and Environmental Effects Research Laboratory Mid

- Continent Ecology Division

– Duluth

.

• Jeff Morris, De puty D irector for Programs , EPA OPPT

.

• Phil Sayre, EPA Deputy National Program Director for the Chemical Safety for Sustainability Research Program

.

• Jim A l wood, Program Manager and Toxic Substances Control Act Nanotechnology Coordinator

, EPA OPPT

, Chemical Control Division

.

• Barbara Karn, Program Director, National Science Foundation; Vice President

, Sustainable Nanotechnology Organization

. In addition to contacting the above nanomaterials researchers, ERG attended the National Nanotechnology Initia tive (NNI) workshop on Stakeholder Perspectives on the Perception, Assessment, and Management of the Potential Risks of N anotechnology in Washington, D.C.

, in September 2013

. 1

To complete the literature review, ERG searched for articles written by SETAC 2012 conference participants and additional researc hers identified from previous contacts using the following search engines:

• American Chemical Society P ublications ( http://pubs.acs.org )

, a comprehensive collection of t he most

- cited

, peer

- reviewed journals in chemi stry and related sciences.

• ScienceDirect ( http://www.sciencedirect.com/ ) , a full

- text scientific database offer ing over 2,500 peer

- review ed journals.

1 The NNI is a U.S. g overnm ent research and development initiative involving the nanotechnology

- related activities of 20 department and federal agency units. For more information on this NNI workshop, including the agenda and presentations, see http://nano.gov/node/102 5

.Memorandum January 23, 2015 Page 5

• Google Scholar ( http://scholar.google.com ) , which provides a broad search of scholarly literature across disciplines, publishers

, and online databases

. In addition to searching by author, ERG scanned titles and abs tracts to identify relevant articles

, using the keywords shown in Table 2 below

. ERG exercised its best professional judgment to create multiple keyword combinations to further focus the literature search. From the articles identified, ERG performed additional sear ches to find other relevant articles from co

authors and references.

ERG created a comprehensive EndNote ® reference library to store and organize references. Because nanotechnology is an emerging field of study, ERG strived to collect the
most recent research , gathering material published from 2006 to December 2013. All articles are government publications

, peer

- reviewed

, or conference proceedings and meet the data quality objectives outlined in the Environmental Engineering Support for Clean Water Re gulations Programmatic Quality Assurance Project Plan ( E RG, 2013 )

.

Table 2 . Keyword Search Terms for Literature Search

Master Terms Chemical Terms General Terms Nano Nanomaterial Nanoparticle Nanoscale Nanotechnology Carbon Carbon nanotubes CNTs Silver Nanosilver TiO 2 Titanium d ioxide Engineered Environmental E nvironmental i mplication/ i mpact Exposure Fate and transport Life c ycle a ssessment Occurrence Production Release Risk Synthesis Toxicity Treatment Wastewater

3. O VERVIEW OF N ANOMATERIALS

Nanomaterials are generally defined as engineered or naturally occurring material s comp o sed of primary particles

, with sizes on the order of 1 to 100 nm in at least one dimension

, that show physical, chemical and biological properties not found in bulk samples of the same material ( U.S. EPA, 2011a )

. These primary particles, termed nanoparticles, may exhibit novel

, size

- dependent characteristics such as increased strength, chemical reactiv ity

, and condu ctivity due to their high surface area

- to

- volume ratio. This proportionally large surface area makes nanoparticles more reactive and responsive to their surroundings and influences mobility, aggregation

, and stability in soil and water ( Gavankar et al., 2012 )

.

A growing community of researchers argue that the primary criterion in any definition of

nan o materials should be novel size

- dependent properties, rather than particle size

, because s ize alone may not reliably predict the fate, transport, and effects of exposure to nanomaterials ( Auffan et al., 2009 ; David, 2013 ; Wiesner et al., 2009 )

.Memorandum January 23, 2015 Page 6

Naturally occurring nanomaterials are ubiquitous in the environment, but have only recently been discovered due to advances in microscopy ( Hochella et al., 2008 ) . The ir background levels and mass distribution are largely unknown. In some cases, nanomaterials may also be incidental, meaning that they are unintentionally produced through industrial activities, notably through emissions from fossil fuel combustion and manufacturing ( Wiesner et al., 2009 )

. Engineered nanomaterials are produced to serve a particular purpose and represent a new or additional input to the environment. The most common ENMs are classified into two categories : carbon

- based and inorganic or metal

- containing ENMs. Table 3 lists c o mmon types of ENMs

.
Table 3 . Common Types of Engineered N anomaterials

Category Engineered Nanomaterial

Carbon

- based ENMs Carbon nanotubes Fullerenes Graphene

Inorganic or metal

- containing ENMs Silver Titanium dioxide Quantum Dots Cerium Oxide Zinc Oxide Iron Copper Silicon Gold Bi

- and tri

- metallic alloys Source: ( SETAC, 2012 ) and (U.S. EPA, 2013a )

.

Some ENMs
, such as cadmium selenide quantum dots and some complex carbon

- based nanomaterials, are completely novel and do not occur in nature. Any of t hese materials detected in the environment can be assumed to be anthropogenic ( ERG, 2008 ; Hochella, 2013 )

. However,

m a ny types of nanomaterials t hat can be engineered also occur naturally in the environment, particularly silver and metal oxides. Silver ENM s are used extensively an anti

- microbial agent s in consumer products, but silver particles on the nanoscale are also found in nature. In addition

, titanium dioxide ( TiO 2 ) nanoparticles that are identical to engineered nanoparticles have been found in rivers that do not receive wastewater discharges and are remote from industrial activities ( Hochella, 2013 )

. Typical concentrations o f naturally occurring and incidental nanomaterials far exceed the total release of EN M s into the environment ( Hochella, 2013 ; Wiesner et al., 2009 ) . However, there is concern that the increased release of E NMs to the environment at large, above and beyond what occurs naturally

, m ay have unintended consequences, especially to ecosystems that have not been exposed to or developed adaptation mechanisms for specific types of ENMs

. The remainder of this memorandum focuses on ENMs.

Based on a conversation with CEINT Director Mark Wiesner

, and available literature
sources, ERG focused the literature review, research, and subsequent discussion presented in this memorandum on the ENM s with the largest produ ction quantities and potential for discharge toMemorandum January 23, 2015 Page 7

the environment from industrial wastewater : silver

, nano

- TiO 2 , and carbon nanotubes ( CNT s ) ( Wiesner, 2013 )

. Quantum dots are a distinctive category of metal

- containing ENMs that do not occur in
nature

. These nano

- sized semiconductors are being investigated for use as biomarkers for biomedical research and for optoelectronic applications , such as solar cells and light emitting diodes, but are just beginning to be translated into commercial products ( Bullis, 2013 )

. Quantum dots have different optical properties depending on their size ( Lowry et al., 2012b ) , and can be synthesized from a variety of metals in solution , most commonly cadmium selenide ( Mahendra et al., 2008 ; Woo, 2013 )

. Although their manufacture could potentially generate an aqueous waste stream, ERG’s literature review indicated that most production is lab scale and information pertaining to the environmental impact, release, or exposure of quantum dots is lim ited ( Musee, 2011 ; Yong et al., 2013 ) ; therefore, ERG does not further fo cus on quantum dots in this memorandum

.

4. E NGINEERED N ANOMATERIAL P RODUCTION M ETHODS , V OLUMES AND P OTENTIAL S OURCES OF I NDUSTRIAL D ISCHARGE

To assess the potential sources and magnitude of industrial wastewater discharges, ERG gathered available information on ENM manufactur ing and ENM process ing into nano

- enabled products (products containing nanomaterials). Manufacturing is the synthesis of ENMs ; p rocessing ( or formulating ) includes any industrial transformation or processing of ENMs into a form that could be used to make nano

- enabled products

, as well as the production of nano

enabled products. E RG also collected information about the generation and handling of aqueous
wast e streams produced during manufacturing and processing. Information about waste generation and management for m anufactur ing and pr o cessing is scarce, but is needed to determine if and where ENMs may be discharged to the environment due to industrial activi ties.

Commercial and consumer e nd use of nano

- enabled products and their waste management are outside the scope of the E ffluent G uidelines P rogram. However, significant discharges of ENM s to the environment may occur from release and degradation during product

use ( Gottschalk & Nowack, 2011 ; Rezić, 2011 ; Windler et al., 2012 )

. Mu eller and Nowack ( 2008 ) estimated that up to 95 percent of silver and TiO 2 nanoparticles could to be transported to
waste water treatment plants due to release from products during their commercial and consumer

use ( e.g., from application of coatings, rinsing of cosmetics or weathering due to abrasion ). Current global production quantities of ENM s are largely unknown and grow th rates are uncertain, but both the rates and types of materials produced are expected t o rapidly increas e

. For example, growth rates from 2006 to 2008 for nano

- enabled products ranged from 10 percent for electronics up to 41 percent for appliances

, and f uture growth is expected to far outpace these
rates ( Musee, 2011 )

. In the absence of wastewater discharge data, information about the inputs (including raw and ancillary materials) and emissions from manufacturing and /or processing is needed to estimate potential ENM discharges. For purposes of the E ffluent G uidelines planning process

, production quantities in themselves do not provide suitable information on potential wastewater discharges without knowledge of the proces ses used to manufacture or process ENMs. The identification of aqueous waste streams generated from manufacturing and processing is the firstMemorandum January 23, 2015 Page 8

ENM Production and Waste Streams Data Gaps:

• Unknown universe of facilities manufacturing and processing ENMs

• No current data quantifying wastewater discharges of ENMs from manufac turing or processing

• Little publicly available data quantifying ENM production volumes from manufacturing or processing

• Unknown generation of aqueous waste streams from manufacturing and processing of ENMs

• Unclear understanding of current ENM waste handlin g/management practices step in determining whether industrial wastewater could be a source of environmental releases of ENM s

.

Th e following section s describe the production methods and various routes by which ENM s could enter the environment from the ir manufacturing and processing into nano

- enabled products . It is important to stress that these are p otential routes of release

. Very l ittle i s know n about the actual release of ENMs to the environment

, and there are currently no standardized techniques to monitor emissions and environmental concentrations ( Gottschalk & Nowack, 2011 )

. If a particular process generates an aqueous waste , the nex t step is to identify how the waste is handled and in particular, if the waste is discharged to surface waters or POTWs

. From its review of current literature and research, ERG did not identify any information documenting the release or measurement of ENM s in industrial wastewater from manufacturing or processing activities.

4.1 ENM Production and Waste Streams

V ery lit tle public ly available information exists to characterize the waste streams from ENM manufacturing and processing or describe how the aqueous wastes are managed and disposed

. Several papers, especially those on the topic of life cycle assessment , discuss the need to quantify both production and release of ENM s and analyze or model possible waste stream pathways ( Gavankar et al., 2012 ; Gottschalk et al., 2 009 ; Musee, 2011 )

. The literature also suggest s that the processes associated with the manufacturing and processing of ENMs may create aqueous waste stream s ( Eckelman et al., 2012 ; Musee, 2011 )

.

Commercial ENM manufacturing methods and volumes are often proprietary and are not shared publicly. The EPA Nanoscale Materials Stewardship Program solicited voluntary reports from U.S. companies producing ENMs in 2008 ( U.S. EPA, 2013c ) . The program estimated that about 600 companies manufactured , processed

, or used nanotechnology in 2005 ; although the
program expected reports from 240 entities, it received only 31. Of the companies that responded, only two publicly reported any production data . These two reported manufacturing capacity but not the actual quantities of ENMs manufactured ( Hendren et al., 2011 )

. In a separate effort, Duke University researchers, using data from patents, company websites, and requests, identified 30 companies producing silver , nano

- TiO 2 , or CNTs (provided in Appendix B ) ( Hendren et al., 2011 )

. ERG has not contacted any U.S. companies for information regarding manufacturing and processing methods or production quantitie s

.

4.1.1 Manufacturing of ENMs

From its review of the literature, ERG identified t he following manufacturing methods as well as research and development (R&D) lab oratory methods use d to synthesize ENM s

. Depending on the post

- processing steps, the resulting ENM may be in the form of powders,
sprays , or solutions

. The manufacturing methods ERG identified are published in peer

- review literature and do not necessarily characterize a process from a particular company or laboratory.Memorandum January 23, 2015 Page 9

Silver nanomaterials can be synth esized using several physical and chemical methods

. The y are often produced in dilute aqueous solutions by chemical reduction. S ilver salts are reduced by sodium borohydride , citrate, ascorbate

, or another reducing agent ( Fabrega et al., 2011 ; Mulfinger et al., 2007 )

. In addition, researchers are investigating b iosynthesis processes ( e.g. , using fungi ) to generate silver nanoparticles ( Fabrega et al., 2011 )

. Single

- walled carbon nanotubes are manufactured by three gas

- phase processes: chemical vapor depositio n , arc ablation

, and high

- pressure carbon monoxide ( Eckelman et al., 2012 ; Healy et al., 2008 )

. Multi

- walled CNT s are often man ufactured using chemical vapor deposition ( Plata et al., 2009 )

. These synthesis processes do not generate an aqueous waste stream , but they are followed by a n aqueous purification step. Purification may involve several rinses with one o r several of the following solutions: deionized water, nitric acid , sodium hydroxide

, and ethanol ( Healy et al., 2008 )

. The use of a n aqueous purification rinsing scheme suggests that CNT manufactur ing could generate an aqueous waste stream, but ERG did not identif y any i nformation related to the onsite treatment and /or subsequent disposal of the waste stream

.

EPA’s OPPT recently promulgated S ignificant N ew U se R ules (SNURs) for CNT s under the authority of the Toxic Substances Control Act, which became effect ive in August and October 2013 ( U.S. EPA, 2013a

, 2013e )

. These SNURs require entities that intend to

manu facture

, process , or use certain CNTs to notify EPA at least 90 days b efore engaging in a significant new use

. Any S ignificant New Use not ices made under th e s e SNUR s will give EPA the opportunity to evaluate the intended new use s of the CNTs and, if necessary, to limit or prohibit activity to mitigate any unreasonable risk s to hu man health and the environment

.

Titanium dioxide nanomaterials are manufactured by gas

- and wet

- phase synthesis methods. About 60 percent of the world ’s manufactured nano

- TiO 2 is synthesized th r ough a gas

phase chloride process ( Liu et al., 2013 ) ; however, ERG did not find in formatio n on how much of the nano

- TiO 2 produced in the U.S. is manufactured through this process

. Nano

- TiO 2 is also synthesized by wet

- phase methods , includ ing sulfate, sol

- gel

, and hydrothermal methods ( Liu et al., 2013 ; Robichaud et al., 2009 )

. Both gas

- and wet

- phase nano

- TiO 2 synthesis methods potentially produce aqueous waste
stream s . Early methods of synthesis generally occurred in solution, but combustion (gas

- phase) processes have evolved to allow greater control, efficiency

, and output of products ( Healy et al., 2008 )

. The use of gas

- phase synthesis methods may significant ly reduce potential wastewater discharges; however

, s teps common to both gas

- and wet

- phase synthesis may generate aqueous waste, for example, during purification and washing of the nanomaterial. From its review of literature and current research, however, ERG did not find information describing how the nano

TiO 2 aqueous waste s from industrial manufacturing processes are managed

. Although not much is known about waste handling, u nused reagents and chemical wastes from manufacturing are strictly managed and likely to be handled as hazardous waste

, and not released in wastewater ( Eckelman et al., 2012 ) . In addition, researchers sugges t that laboratory

generated waste streams are probably recovered or reused due to the high cost of p roducing ENMs ( Wiesner, 2013 )

. However, cleaning or washing of laboratory equipment may be a potential source of wastewater. Equipment, such as glasswar e, is typically cleaned first withMemorandum January 23, 2015 Page 10

solvents before being washed with detergents and water in a sink. The solvents are disposed of as hazardous waste, while detergents, water, and any residuals may be discharged as wastewater.

4.1.2 Processing /Formulating

After manufactur ing

, ENM s are often further processed and incorporated into nano

enabled product s

. Nano

- enabled products are used across many industrial sectors . They are used extensively for biomedical and electronics applications, and incorporated into indust rial and domestic products, chemicals, and construction materials. TiO 2 ENMs are used as catalysts and are included in paints, coatings, plastics, paper

, and cosmetics . Silver ENMs are widely used in consumer products , such as cosmetics and kitchen product s, for their antimicrobial properties. CNTs are used in the electronics and polymer industries , with ongoing research into their applications for the energy and consumer goods sectors ( Mueller & Nowack, 2008 )

. Transforming manufactured E N M s into nano

- enabled products may require one or several intermediate handling and processing steps. These intermediate processing steps may occur at the primary manufacturing facility or a separate facility before the ENM is formulated into a nano

- enabled product. The extent of p rocessing is likely proprietary and could be highly variable, depending on the intended use

. As a result

, ERG could not identify adequate information to describe the nature of and variability of intermediate processing.

The extent and number of ENM processing and formulating facilities is unknown, but literature and current research suggests that they likely far outnum ber facilities that solely manufacture ENMs. The EPA Nanoscale Materials Stewardship Program estimated that about 600 companies manufactured or applied nanotechnology in 2005 ( U.S. EPA, 2013c ) , but the number of companies has most likely significantly increased since then

. Further, some
processors may use ENM s or nano

- enabled devices to manufacture products that do not contain nanomaterials

.

Research ers indica te that processing and production of nano

- enabled products may be more likely to produce a n aqueous waste stream than manufacturing ENMs because many of the

nano

- enabled products may be formulated with the ENMs in solution ( Wiesner, 2013 )

. A variety of aqueous waste streams may be generated during processing, depending on the product and industry. However, information is not currently sufficient t o characterize and quantify the waste streams generated from ENM processing or describe how the waste streams are handled and ultim ately disposed

.

4.2 Environmental Concentrations of Nanomaterials
Researchers do not currently have a good understanding of the concentrations of engineered or naturally occurring nanomaterials in the environment ( Hochella, 2013 ; Wiesner et al., 2011 )

. Information on background environmental concentrations of nanomaterials could be used to identify releases of ENMs based on areas with unnaturally high concentrations and to evaluate the inputs from potential future emissions from industrial wastewater and other sources

. Knowledge of environmental concentrations is also important for conducting relevant toxicity, risk assessmen t , and life cycle assessment studies.Memorandum January 23, 2015 Page 11

Environmental Concentrations Data Gaps:

• Incomplete data characterizing concentrations of engineered and naturally occurring nanomaterials in the environment

• Little research into the relative contribution of manufac turing, processing, and end use to the quantities of ENMs in the environment To estimate potential exposure and risk to aquatic organisms , r esearchers have developed models t hat predict the ENM concentrations in the environment. Researchers at the Swiss Fe deral Laboratories for Materials Testing and Research (Empa) calculated predicted environmental concentrations (PECs) of several ENM s in wastewater treatment plant (WWTP) effluent ( f rom a combination of industrial and domestic sources ) and surface waters in the U

. S

. based on probabilistic material flow analysis of
current production volumes ( Gottschalk et al., 2009 )

. As shown in Table 4 , t he PECs of ENMs in WWTP effluent are orders of magnitude larger than what is predicted for surface waters

. The researchers then compared the PECs to predicted no effect concentrations (PNEC) from ecotoxicological studies and concluded that silver and TiO 2 ENM s in WWTP effluent may pose a risk to aquatic organisms based on their risk quotients ( Table 4 ). A risk quotient greater than one indicates a need to further evaluate the risk s posed to aquatic organisms

.

Table 4

. Calculated Model Values for Predicted Environmental Concentrations of Engineered Nanomaterials in the U.S.

Engineered Nanomaterial Predicted E nvironmental C oncentration (PEC) (ng/L) WWTP Effluent Risk Quotient (PEC/PNEC) WWTP Effluent Surface Water WWTP Effluent Surface Water Silver 21.0 0.116 30.1 0.17 TiO 2 1,750 2.0 1.8 0.002 CNTs 8.6 0.001 <0.0005 <0.0005 Fullerenes 4.6 0.003 0.023 <0.0005 Sourc e: (Gottschalk et al., 2009 ) Risk quotients greater than one are indicated in bold.
Quantifying production and waste volumes for specific industries and commercial applications is critical for developing life cycle assessment models needed to accurately assess risk associated with environmental release s

. The Empa model was based upon esti mate d worldwide production volumes, which are incomplete and uncertain. Therefore, the significance of the Empa study’s results to the U.S. is uncertain

. T he results do suggest that aquatic ecosystems may be at risk from exposure to silver and TiO 2 ENMs re leased into the environment, though they do not clearly distinguish between potential inputs from releases to wastewater from manufacturing, processing

, and end use

.

5. E NVIRONMENTAL F ATE , T OXIC ITY , AND E XPOSURE

ENM s are likely to be transformed and exist in different forms in the environment than the original form in which they were created

. ENMs undergo complex and dynamic transformations in aqueous media , the extent of which are not fully understood ( Lowry et al., 2012b ) . The different forms in which a nanomaterial can exist will influence fate, reactivity

, and toxicity in the environment. For example, silver can exist as discrete nanoparticles , aggre gated nanoparticles

, or dissolved ions and can form complexes with other molecules

. The following sections describe the physical properties, general fate in the environment and WWTPs

, and known toxicity impacts of silver

, TiO 2 , and CNT ENMs

.Memorandum January 23, 2015 Page 12

Fate and Environmental Transformations Data Gaps:

• Incomplete understanding of how different types of ENMs will interact and transform in aqueous environments

• No studies of ENM fate and transformations in industrial
wastewaters 5.1 Fate and Environmental Transformations

Once released into the environment , ENMs undergo complex and dynamic interactions, transforming and aggregating in aqueous media ( Lowry et al., 2012b ; Wiesner et al., 2011 )

. Several properties of nanomaterials may contribute to their fate, transport and eco toxicity. Particle size and surface area influence the degree of interaction with substances and organisms in the environment. A larger surface area (smaller particle) allows for greater reaction rates ( Healy et al., 2008 )

. Surface coatings that are either engineered

on to the nanomaterial or attach ed through transformations can strongly influence the solubility and reactivity of a n ENM. T he behavior of nanoparticles in the environment is relatively more responsive ( compared to bulk materials ) to the specific conditions of the environment to which the particle is emitted ( Gavankar et al., 2012 )

.

N anopar ticles may be transformed in water through any of the following mechanisms:

• Nanoparticle aggregation

• F ormation of complexes with other molecule s in water

, soil

, or biological systems

• S orption processes

• D egradation

• D issolution of coatings or the core particle

The interactions and transformation s that occur are dependent on the chemistry of the environment, which will affect the mobility and bioavailability of the nanomaterial. In addition, most nanomaterials in the environment tend to aggregate and do not exist as single, dispersed nanoparticles in water ( Zhang et al., 2008 ) . The fate and common interactions of silver, CNT s , and TiO 2 ENMs with the aqueous en vironment are discussed below.

Silver ENMs are spherical particles with high electrical and thermal conductivity ; however, they are best known for their broad antimicrobial properties. Their size and stability are strongly influenced by the conditions under which they are manufactured ( Fabrega et al., 2011 )

. Silver nanoparticles are commonly coated with various polymers that affect the type, rate, and extent of transformations that may occur in aqueous media ( Lowry et al., 2012b )

. The s olubility of silver nanoparticles is highly dependent on surface coating

. For example, c itrate

- coated silver nanoparticles tend to stay in the water phase , while polyvinylpyrrolidone (PVP)

- coated silver nanoparticles more readily partition to solid phases ( Unrine et al., 2012 )

. Silver nanoparticles readily form complexes with sulfur in var ious aqueous media , which can transform the nanoparticle in to many different forms. The nanoparticle can be oxidized into silver ion s or remain as nanoparticle and form complexes with other chemicals in the environment, such as sulfur ( Dale et al., 2013 ) . These transformations are illustrated in Figure 1

. S ilver nanoparticle sulfidation has been demonstrated in many environmental media

, notably during activated sludge treatment in WWTP s ( Doolette et al., 2013 ; Kim et al., 2010 )

, in the lab oratory ( Levard et al., 2011 )

, and in the natural environment ( Levard et al., 2012 ; Lowry et al., 2012a )

. Researchers at CEINT constructed wetland mesocosms to study the long

- termMemorandum January 23, 2015 Page 13

behavior of silver nanoparticles. A study of PVP

- coated silver nanoparticles indicated that a majority of the silver nanoparticles were transformed to silver

- sulfide compounds and primarily partitioned to soils and sediments (70 percent by weight) ( Lowry et al., 2012a ) . Researchers at Carnegie Mellon University reported tha t silver nanoparticles are transformed to similar chemical forms as bulk silver in a pilot WWTP ( Ma et al., 2013 )

.

Adapted from Dale et al., 2013.

Figure 1 . Representation of Chemical Transformations of Silver Nanoparticles with Sulfur in Aqueous Environments

Titanium dioxide ENMs are crystalline and can be as small as a few nanometers in diameter. This small size and large surface area provides an excellent catalyt ic surface . Their effective ness at absorbing UV light makes them useful in sunscreens, other cosmetics, and coatings ( Hendren et al., 2011 ; Robichaud et al., 2009 )

.

TiO 2 nanoparticles are highly r eactive with sunlight, and can act as catalysts. This behavior can vary depending on the form and surface coatings of nano

- TiO 2 , which has certain implications for toxicity ( discussed in Section 5.3) ( U.S. EPA, 2010b )

. Nano

- TiO 2 is fairly soluble in water and solubility increases when organic material is present. Studies on environmental transformations of nano

- TiO 2 are limited ( Liu et al., 2013 )

. The nanoparticles have a strong tendency to form aggregates at neutral pH , but a ggregation strongly depends on the chemistry of the medium ( Liu et al., 2013 )

.

Carbon nanotu bes can be described as one

- atom

- thick sheets of carbon rolled into a tubular shape. Single

- walled CNT s have a diameter of approximately 1 nm, a length of several microns, and a tendency to curve. Multi

- walled CNT s contain a t least two layers, with diameters typically ranging from 3 to 5 0 nm ( Petersen et al., 2011 ) . The bonding structure of CNTs gives rise to unique properties, such as metallic conduction, semi

- conduction

, and tensile strength approximately 50 times that of steel ( Healy et al., 2008 )

.

CNTs have a high affinity to partition to solid media

. However, CNTs may stay suspended in water in aqueous environments with high concentrations of dissolved organicMemorandum January 23, 2015 Page 14

Wastewater Treatment Data Gaps:

• No data quantifying industrial wastewater treatment removal performance of ENMs

• No data characterizing and quantifying ENMs in biosolids produced from industrial wastewater treatment, or their associated risks for land application matter. T he environmental transformations CNTs undergo are not well understood, and may vary depending on the structure of the CNTs ( Petersen et al., 2011 ) . The chemistry of the environment

can also change the physiochemical properties of CNTs, which can affect their beha vior . For example, high

- salinity environments increase CNT aggregation ( Eckelman et al., 2012 )

.

5.2 Fate in Wastewater Treatment Plant s

Presence and fate of nanomaterials has been studied in municipal wastewater , in part to determine how well current municipal treatment systems remove ENM s from wastewater

. In general, municipal WWTPs with post

- secondary treatment should remove the majority of nanoparticles from the waste water by transfer from the wastewater to the sew age sludge (biosolids generated as a byproduct of wastewater treatment )

. Research on the performance of several treatment processes to remove nanomaterials is discussed below. H owever, the applicability of municipal wastewater research to industrial wastew ater is unknown. Nanomaterial react ions and transform ations may vary depending on the aqu eous environment , and industrial wastewater tends to have higher concentrations and varieties of constituents than either municipal wastewater or the ambient environme nt

.

Researchers have studied n anomaterial fate in suspended growth biological wastewater
treatment and filtration processes

. Silver, CNTs, and TiO 2 nanoparticles readily attach to biomass, resulting in partitioning to the sewage sludge ( Wiesner, 2013 )

. More than 90 percent of nanomaterials may leave wastewater via this sorption mechanism and subsequent filtration during wastewater treatment , but removal efficiency strongly depends on the size of the nanomaterial s . Smaller nanoparticles, e.g., 30 nm or less, have been detected in WWTP effluent ( Westerhoff et al., 2011 )

.
In addition, n anomaterials tend to aggregate in water , so conventional sedimentation processes can be effective in removing them from wastewater

. Conventional coagulation and sedimentation can remove 20 to 60 percent of total nanoparticle s, as measured by mass ( Zhang et al., 2008 )

. However, typical sedimentation processes cannot remove discrete and stable nanoparticles with sizes less than 0.1 microme ters ( Westerhoff et al., 2013 )

. After conventional treatment, tertiary f iltration processes can further remov e nanomaterials from the water

. For example, WWTPs u s ing m icrofiltration removed TiO 2 nanoparticles more effectively than those using conventional settling methods ( Westerhoff et al., 2011 )

. TiO 2 nanoparticles can be removed from wastewater through granular media filtration, but remova l efficiency is strongly dependent on the filtration media and water chemistry. Diatomaceous earth granular filtration was effective in capturing and retaining TiO 2 nanoparticles at a concentration of 50 mg/ L ( Rottman et al., 2013 )

. ERG did not identify research

on nanomaterial removal performance in industrial WWTPs or discrete treatment processes other than filtration and sed imentation.

Biosolids generated from wastewater treatment are often used as fertilizers and land application of biosolids is considered a potential major source of environmental exposure to ENMs ( Lowry et al., 2012b ; Westerhoff et al., 2013 )

. Researchers have identified andMemorandum January 23, 2015 Page 15

Toxicity and Exposure Data Gaps:

• Limited toxicity studies on the relevant forms and concentrations of nanomaterials that may be present in complex media, such as industrial wastewater

• Limited measurements and hazard assessments of ENMs in complex, natural systems

• Incomplete understanding of environmental and human health impacts characterized silver and TiO 2 nanoparticles i n U.S. municipal wastewater sludge samples , which raises concerns about this potential exposure pathway ( Kim et al., 2010 ; Kim et al., 2012 )

.

5.3 Toxicity and Exposure

N umer ous toxicity studies have reported hazards to microbial and aquatic organisms; however, research has focused on toxicity in controlled laboratory environments using ENMs in the form s in which they were created. T hese results are difficult to extrapolate to ecosystems, where exposures will likely be at low er concentrations and where

a diversity of organisms is present ( Colman et al., 2013 )

. Some r esearchers recommend that fate and toxicity

m easurements should be made in complex, natural systems in order to accurately assess hazards ( Lowry et al., 2012b ; Wiesner et al., 2009 )

. It is also important to take environmental transformations into consideration, and investigate toxicity in the form s t hat ENM s exist in an ecosystem ( Gottschalk & Nowack, 2011 ; Lowry et al., 2012b )

. The primary toxicity mechanism for silver nanomaterials is the ir dissolution into silver ions ( Arnaout & Gunsch, 2012 ; Nowack et al., 2011 )

. Toxic effects from silver nanomaterials in humans are only obser ved at very high conc entrations ( Nowack et al., 2011 )

, but s ilver ions cause oxidative stress in microorganisms and aquatic organisms ( Yang et al., 2012 )

. Because of their tendency to diss olve in aqueous media, silver E N M s are often coated to stabilize the particle s

.

Th ough many toxicity studies to date were conducted us ing untransformed nanoparticles in laboratory environments

, toxicity studies that were conducted in simulated natural environments ( mesocosms ) and natural environments have reported fewer toxic effects

. This suggest s that the impacts of ENMs are affected and potentially dampened by environmental transformations

, microbial activity , and the physical and chemical properties of the environment ( Colman et al., 2012 ; Unrine et al., 2012 )

. Researchers at CEINT have shown that the short

- term impacts of silver nanoparticles on microbes are attenuated by stream water and sediment ( Colman et al., 2012 )

. However , even low doses of silver nanoparticles may have appreciable

e ffects on an environment. For example, a dose of 0.14 mg/kg soil of PVP

- coated silver nanoparticles applied to wetland mesocosms reduced the microbial and plant biomass each by 35 percent and significantly shifted the wetland microorganism population ( Colman et al., 2013 )

.

S ilver has been used for over 100 years as an anti

- microbial agent

. However, i t is unclear whether silver nanoparticles exhibit novel toxicity mechanisms, outside of generating silver ions. Therefore, t he ob served toxicity effects in silver nanoparticles may not differ from those of bulk or colloidal silver ( No wack et al., 2011 )

. There is also concern that nanomaterials may affect biological processes in WWTPs

. R esearchers at t he University of Adelaide in Australia added silver nanoparticle s to aerobic and anaerobic wastewater treatment batch reactors to test the ir effect on microbial populations. They found that addition of silver nanoparticle s had no effect on nitrification rates and methane production, but shifted niche microbial populations in both reactors ( Doolette et al., 2013 )

.Memorandum January 23, 2015 Page 16

Titanium dioxide ENMs m ay exhibit ecotoxicity impacts because of their catalytic surface ( Hochella, 2013 ) . Nano

- TiO 2 can be activated by photons (sunlight) to produce reactive oxygen species, which cause cellular damage. Nano

- TiO 2 ha s been shown to suppress the grow th of freshwater green algae , which is a concern for freshwater habitats ( Cardinale et al., 2012 )

. Nano

- Researchers have observed photo

- dependent mortality effects in model organisms exposed to nano

- TiO 2 in the p art p er b illion range ( Alloy & Roberts, 2012 ; Heideman et al., 2012 )

. This implies that exposure to sunlight in ecosystems with nano

- TiO 2 may threaten organisms in shallow surface waters and soil s

. However, more research is needed to determine

nano

- TiO 2 impacts on aquatic ecosystems and microorganisms in particular.

The toxicity of carbon nanotubes is strongly affected by their structure

. An important mechanism of CNT toxicity is the production of reactive oxygen species

, as the ability to generate reactive oxygen species may increase as the size of the nanotube s decrease ( Chae et al., 2011 )

. Various studies have shown that exposure to CNTs can cause growth inhibition, hatching delays, and mortal ity in some aquatic organisms ( Petersen et al., 2011 )

.

C urrently, human health effects of exposure to ENM s in any environmental medium are not fully understood, but risks are presumed to be rather low. However, there have been recent efforts to minimize airborne exposure to ENMs in the workplace , due to concern for inhalation hazards

. In 2013, the National Institute for Occupational Safety and Health ( NIOSH) published guidelines to minimize workplace exposure to ENM s ( NIOSH, 2013 )

. In addition, the Occupational Safety and Health Administration ( OSHA ) published recommended best practices and exposure limits for airborne CNTs and TiO 2 ENMs ( 2013 )

. There is concern that multi

walled CNTs generate asbestos

- like toxicity, however, this effect can be mitigated by decreasing the e ffective length of the nanotubes ( Ali

- Boucetta et al., 2013 )

. While airborne exposure is not a direct concern for the E ffluent G uidelines P rogram , concerns about airborne ENM concentrations may increase future use of wet scrubbers for air pollutio n control, with possible generation of an ENM

- containing wastewater.

H umans are exposed to TiO 2 and silver nanoparticles outside the workplace because of
t heir use in person al care products (e.g., cosmetics and sunscreens) , textiles

, and other consumer goods. Current information indicates that human health risks are low, but there is ongoing research into the physiological responses and human health outcomes from exposure to these and other types of ENMs

.

6. A NALYTICAL METHODS

Methods for detecti ng, quantifying

, and characterizing nanomaterials in any aqueous media

— let alone a complex, high

- strength medium such as industrial wastewater

— are not fully developed. EPA has not approved standardized methods for sampling, detecti ng , monitoring, quantif yi ng, o r characteriz ing nanomaterials in aqueous media. This is a critical area of research because the ability to detect and characterize nanomaterials is essential to understanding the implications of thei r release in to the environment ( U.S. EPA, 2010a )

. EPA approved methods are also needed to support any future potential regulatory structure for industrial discharges of ENMs

.Memorandum January 23, 2015 Page 17

Analytical Methods Data Gaps:

• No EPA standard methods to detect, monitor, characte rize

, and quantify nanomaterials in complex environmental media

• No current standard sampling protocols

• For some ENMs, inability to distinguish between naturally occurring, incidental, and engineered forms 6.1 Method Development
Many U.S. and international organizations are working to develop guidance and standards for ENM characterization

. These organizations include, but are not limited to standard

- setting groups, such as the International Standardization Organization (ISO), AST M International

, and the American National Standards Institute (ANSI) ; U.S. f ederal research led by the National Institute of Standards and Technology (NI ST) is also relevant ( NNI, 2013b )

. The Organis ation for Economic Co

- operation and Development (OECD) has published guidance for safety testing and characteri zation of toxicological properties of ENM s. It is recognized as a living document, subject to refinement as research into the development of nanomaterial test method s progresses ( OECD, 2012 )

.

S pectroscopy and spectrometry methods are commonly used an d being further developed to detect and characterize nanomaterials in the laboratory. Direct visualization and determination of nanoparticle size and shape is often accomplished through electron microscopy. Transmission electron microscopy (TEM) can produc e images with spatial resolutions greater than 0.1 nm

, while s canning electron microscopy (SEM) can achieve resolutions between 1 nm and 1 μ m. Electron microscopy is often coupled with other measurement techniques, such as energy

dispersive x

- ray spectroscopy (EDS) to determine structure and chemical c omposition

. However, most of these methods are not appropriate for analyzing nanomaterials in complex media, such as industrial wastewater, typically because they require a simple matrix to accurately measure samples.

Researchers are developing n ew tools to characterize nanomaterials in complex media, which could then be applied to industrial wastewaters. For example, h yperspectral i magery with

e nhanced d arkfield microscopy has been used to detect, ch aracterize

, and analyze silver nanoparticle s in complex waters ( Badireddy et al., 2012 )

. EPA ’s ORD is using single

- particle inductively coupled plasma mass spectrometry (SP

- ICPMS) to measure concentration and metal mass of inorganic nanoparticles in complex aqueous media ( U.S. EPA, 2010a

, 2011b ) . Mobile application of laser

- induced breakdown detection (LIBD) is another promising method for detect ing particle size and number density for nanoparticles in aqueous suspensions ( Latkoczy et al., 2010 )

. ERG’s literature search identified a larger body of research develop ing methods to characterize metal

- containing nanomaterials in complex media as compared to carbon

- based nanomaterials. Table 5 outlines these and other analytical methods ERG identified . For a comprehensive review of analytical methods, see Sampling and Analysis of Nanomaterials in the Environment: A State

- o f

- t he Science Review ( ERG, 2008 ) and Characterizing Concentrations and Size Distributions of Metal

- Containing Nanoparticles in Waste Water ( U.S. EPA, 2010a )

.Memorandum January 23, 2015 Page 18

Table 5 . Common Measurement Methods and Characterization Metrics for ENMs

Measurement Methods Characterization Metric Average Surface

Area Chemical Composition Geometry and Shape Size Distribution by Diameter Size Distribution

by Mass Atomic absorption spectrometry (AAS) ✔ Atomic/optical emission spectrometry (AES) ✔ Atomic force microscopy (AFM) ✔ 2 ✔ ✔ Brunauer

- Emmett

- Teller method (BET) ✔ Capillary e lectrophoresis (CE) ✔ Dynamic l ight s cattering (DLS) ✔ 1 ✔ Energy

- dispersive x

- ray spectroscopy (EDX/EDS) ✔ Electron energy loss spectroscopy (EELS) ✔

Field

- flow fractionation (FFF) ✔ 1 ✔ Surface area sedimentation field

flow fractionation (Sed

- FFF) ✔ ✔ Hydrodynamic c hromatography (HDC) ✔ Hyperspectral i magery with enhanced d arkfield microscopy (HI) Silver nanoparticles only Silver nanoparticles only Single particle

- i nductively coupled plasma mass spectrometry ( SP

ICPMS) ✔ ✔

Laser

- induced breakdown detection (LIBD) ✔ Nanoparticle t racking a nalysis (NTA) ✔ Scanning electron microscopy (SEM) ✔ ✔ Synchronous l uminescence

s pectroscopy (SLS) ✔ 1 ✔ Scanning probe microscopy (SPM) ✔ ✔ Transmission electron microscopy (TEM) ✔ 2 ✔ ✔

Sources : (Badireddy et al., 2012 ); (ERG, 2008 ); (Latkoczy et al., 2010 ); (Madden et al., 2006 ); (U.S. EPA, 2010a

, 2011b )

. 1 SLS us ed with DLS or FFF ( U.S. EPA, 2010a )

. 2 Surface a rea calculated using measurements from TEM and AFM ( Madden et al., 2006 )

.

Two current projects to develop field sampling or rapid screening nanoparticle detection methods were discussed at SETAC 2012. Researchers at State University of New York at Bingham ton ( SUNY

- Binghamton ) are developing a novel membrane for application as a sensor to isolate, detect

, and quantify ENMs in complex environmental matrices ( Sadik et al., 2012 )

. Researchers at Trent University are developing three types of p assive sampling devices to detect silver nanoparticles in natural waters ( Fischer et al., 2012 )

.Memorandum January 23, 2015 Page 19

6.2 Sampling Protocols

There are no standard protocols for collecting aqueous samples for nanomaterial analysis. Due to their low environmental concentrations, e xtra consideration should be taken to minimize the risk of contamination ( ERG, 2008 )

. Nanoparticles are constantly changing various states of aggregation and dispersion in aqueous media ( Wiesner, 2013 ) , so sample preservation and holding times may affect nanomaterial structure and hence the results of subsequent
measurement s

. Nanoparticle stability in water is dependent on water chemistry , especially pH, which may necessitate development of nanomaterial

- specific and water

- quality

- specific sampling protocol s

.

6.3 Challenges for Monitoring in Complex Environmental Media

Standard m ethods to monitor and quantify nanomaterials in complex environmental media , like industrial wastewater, are not yet developed

. M any of the analytical methods developed to date characterize nanomaterials in simple media. With additional research, some of these methods may be refined and adapted to characterize ENMs in complex environmental media. Once standardized detection methods are developed to measure ENM discharges to , and concentrations in

, the envi ronment , strategies will be needed to distinguish between engineered and naturally occurring nanomaterials to fully inform monitoring. E ngineered and naturally occurring nanoparticles are often indistinguishable under a microscope ( Hochella, 2013 ; Wiesner et al., 2011 )

. For example, TiO 2 nanoparticles that are identical to manufactured nanoparticles have been found in rivers that d o not receive wastewater discharges and are remote from industrial activities ( Hochella, 2013 )

. Therefore, i t may be important to assess present environmental concentrations as a strategy to distinguish the source s of nanomaterials in the environment ( Gottschalk et al., 2009 )

.

7. N ATIONAL N ANOTECHNOLOGY I NITIATIV E

The NNI is a collaborative, interagency U.S. g overnment research and development initiative. The NNI provides a framework for individual and cooperative nano technology

- related activities for 20 federal department and agency units , including EPA, with a r ange of research and regulatory roles and responsibilities. The NNI expedites the discovery, development

, and deployment of nanoscale science and tech nology to serve the public good; this is accomplished through a program of coordinated research and develo pment aligned with the missions of the participating agencies ( NNI, 2013c )

. NNI agencies an d academic research centers coordinate research that may facilitate EPA’s unders tanding of the potential for wastewater discharges from ENM manufacture and processing and potential impacts on the environment

. The 2014 NNI Strategic Plan describes the high

- level goals, priorities and specific objectives

, for at least the next three years

, related to nanotechnology research but does not provide performance measures or timeframes for meeting the objectives ( NSET, 2014 )

. The NNI Strategic Plan describes several areas of research focu sed on the environmental, health, and safety implications of nanotechnology ( NSET, 2014 ) . A subset of these research areas, listed below, may inform EPA’s assessment of the presence and impact of ENM s in industrial wastewater discharge:

• N anomaterial measurement infrastructureMemorandum January 23, 2015 Page 20

• P r edictive modeling and informatics

• H uman exposure and health

• E nvironmental health

• R isk assessment and risk management

The NNI Strategic P lan also establishes Nanotechnology Signature Initiatives to spotlight topical areas that exhibit particular promise, existing effort, and significant opportunity, and to accelerate their development ( NSET, 2014 )

. O ne initiative in particular applies to the needs of the Effluent Guidelines P rogram: Nanotechnology for Sensors and Sensors for Nanotechnology. This initiative aims, in part, to suppo rt research and develop ment methods and devices to detect and identify ENMs across their life cycles ; this will allow researchers to assess the potential human health and environment al impact s of ENMs

. NNI member agencies also fund, in part, much of the ongoing research discussed in this section ( e.g., research by the National Science Foundation, NIST, NIOSH, OSHA, and others)

. In particular, EPA supports research on environmental exposure, impacts, risk assessment, and analytical method development throu gh the National Center for Environmental Research and extramural grant , fellowship

, and research contract programs ( NNI, 2013a )

.

8. S UMMARY OF R ESEARCH AND D ATA G APS
Nanotechnology is a rapidly progressing field, expected to continue to grow as the

n umber of prod ucts and technological applications increases. Some manufacturing and processing methods likely generate wastewater, potentially for each of the ENMs of interest (silver, nano

- TiO 2 , and CNTs), but the quantity generated and waste management practices are

n ot documented

. A s the number of ENM s and nano

- enabled products increase s , so will their potential to be release d into the environment through industrial wastewater and other emissions

. This growth in ENM manufacturing has been accompanied by some research into ENMs’ presence and fate in wastewater. M ethods for de tecting and characterizing nanomaterials in complex media, including industrial wastewater

, are under development

. Research has also shown that common treatment technologies used in municipal WWTPs are effective at removing nanomaterials from the wastewater

, and some nanomaterials ( i.e., silver , TiO 2 ) have been detected in U.S. WWTP biosolids

. Despite the body of current research, ENMs present a challenge for en vironmental monitoring, risk assessment, and regulation du e to t he ir small size, unique properties

, and complexity. EPA has not approved any standardized methods for sampling, detection, or quantification of nanomaterials in aqueous media. New methods and means of quantification need to be developed to assess the environmental implications of ENMs and inform future regulatory decisions

. While some exposure hazards have been demonstrated, t he environmental and human health risks associated wi th these materials are largely unknown

. Fate and toxicity assessments for ENM s, in the forms and relevant concentrations to which organisms will be exposed

, are needed to accurately determine risk. I ndustrial wastewater releases of ENMs to the environment have not been studied in detail

.

The data gaps listed below identify research necessary to assess the hazards and implications of the environmental release of ENMs via industrial wastewater discharge

. ERG has also identified p rominent academic, EPA

, and international organizations that are currentlyMemorandum January 23, 2015 Page 21

conducting research in these areas. Th is information is a summary based on sources reviewed as of December 2013

, described in Section 2.0.

1. S tandard methods and sampling techniques to detect and character ize nanomaterials in industrial wastewater

Standard methods to detect and characterize nanomaterials have not been fully developed, but are critical for determin ing the extent of nanomaterials in industrial wastewater and to support any potential future regulation of their discharge . Development of standard methods will also support research into the environmental implications of nanomaterials and especially aid in research regarding fate and transport needed for more accurate exposure and risk assessments

. Many of the analy tical methods developed to date characterize nanomaterials in simple media. With additional research, t h ese methods may be refine d and adapt ed to characterize ENMs in complex environmental med ia, including industrial wastewater

. The following organizations (among others) are currently researching and developing analytical methods to characterize E NMs in simple and complex media.

Table 6 . Prominent Organizations Developi ng Analytical Methods for ENMs

Organization Analytical Method Nanomaterial EPA Office of Research and Development, National Exposure Research Laboratory

, Environmental Sciences Division ( EPA ORD/NERL/ESD ) Screening and characterization methods Metal

- containing nanomaterials

Swiss Federal Institute of Aquatic Science and Technology ( Eawag ) Electron microscopy (SEM, ESEM, TEM, EDX); mobile LIBD Not specified

Center for the Environmental Implications of Nanotechnology ( CEINT ) Testing protocols; h yperspectral i magery with enhanced d arkfield microscopy Silver , TiO 2 , and other metal oxides

University of California Center for Environmental Implications of Nanotechnology ( UC

- CEIN ) Testing protocols; m icroscopic and

s pectroscopic m ethods Metal oxides, CNTs and others not specified

Arizona State University ( ASU ) Detection and characterization of ENM s during water treatment Silver , TiO 2

Like analytical methods, research into real

- time monitoring techniques to quantify nanomaterials in complex media, like wastewater

, is in its infancy. T he NNI identified development of devices to detect and identify ENMs across their life cycles as a priority, and aims to accelerate research through its initiatives

. In addit ion, EPA has supported analytical method research through the National Center for Environmental Research and grant programs , which fund, in part, some of the ongoing research discussed in this memorandum ( NNI, 2013a )

. ERG identified t he following organizations researc h ing real

- time monitoring and field sensing methods for complex media:

• ASU (d etection of CNTs in complex media )

.

• Trent University (d etection of s ilver E NMs )

.

• SUNY

- Binghamton (m embrane sensor to detect and quantify ENMs )

.Memorandum January 23, 2015 Page 22

Because of their low environmental concentration and tendency to transform in the environment, nanomaterial

- specific sampling techniques may be needed to ensure that sample collect ion does not compromise the quality and reliability of measurement methods a nd results

.

2. S tudies on toxicity and exposure to ENMs in complex media, including industrial
wastewater

Existing laboratory studies of the ENMs of interest have shown toxicity impacts on aquatic organisms and the environment. The primary mechanism of tox icity for silver nanomaterials is their dissolution into silver ions , which cause oxidative stress in organisms

. However, that ecotoxicity may be attenuated in natural environments. T iO 2 nanomaterials and CNTs can form reactive oxygen species that cause cellular damage.

Currently, human health effects of nanomaterials in any environmental medium are not fully understood, but risks are presumed to be rather low. However, there have been recent efforts by OSHA to minimize airborne exposure to nanomaterials in the workplace.

Though numerous laboratory toxicity studies have been conducted , research has focused on toxicity in controlled laboratory environments using ENMs in the form s in which they were created. ERG did not identify any studies on toxicity fro m exposures to ENMs in industrial wastewater to date. Toxicity studies to date largely have not consider ed relevant forms and concentrations of nanomaterials that may be present in complex media, such as industrial
wastewater

. In addition, few t oxicity stu dies have been conducted within complex media and ecosystems, where exposures will likely be at low er concentrations and where a diversity of organisms are present ( Colman et al., 2013 ) . The complex interactions and interdependencies within an ecosystem, especially at the microbial level

, will influence the hazard effects of ENMs.

T he following organizations are conducting toxicity assessments in complex media and/or environments:

• EPA Mid

- C ontinent Ecology Division ( assessing toxicity of ENMs to aquatic species, particularly nano

- TiO 2 )

.

• CEINT ( silver, zinc, and cerium oxide exposure and toxicity in simulated wetland

mesocosms )

.

• Trent University (s ilver nanoparticles in lake mesocosms

— the LENS Project)

.
3. Universe of f acilit ies

, production volumes

, and waste generated from ENM manufact ur ing and processing

A major data gap is the lack of information on the facilities manufacturing and processing ENMs
, as well as production quantities and waste volumes generated. Data collection efforts from EPA ’s Nanoscale Materials Stewardship Program in 200 8 suggest that the number of facilities manufacturing or processing ENMs may be on the order of hundreds to several thousand facilities. Further, the Nanotechnology Consumer Product Inventory ( Project on Emerging Nanotechnologies, 2014 ) identified over 800 consumer products containing nanomaterials in the U.S. These data sources indicate that nanomaterials processing spansMemorandum January 23, 2015 Page 23

multiple industrial categories , however, little progress has been made to date to quantify production volumes.

Although a vailable l iterature suggest s that a queous waste streams are likely generated through manufacturing and processing of CNTs, silver, nano

- TiO 2 , a nd other ENMs , it is unclear how the se waste streams are managed and ultimately disposed

. Further, ERG did not identify any studies on the presence or quanti ty of ENM s discharged in industrial wastewater.

To inform future potential actions and decisions for the Effluent Guidelines P rogram related to nanomaterials, i nformation on ENM production and waste generation and management is needed . This information will help EPA accurate ly assess life cycle and exposure pathways, which in turn will better inform hazard and risk assessment s ( Gavankar et al., 2012 ; Gottschalk et al., 2009 )

. The following organizations (among others) are conducting research on production volumes

, r is k

, and l ife c ycle a ssessment s :

• EPA NRMRL (l ife cycle assessment and impact assessment models ).

• EPA OPPT ( SNURs for CNTs ).

• UC

- CEIN (e nvironmental r isk m anagement and r egulation ; r isk p erception ).

• CEINT (e stimation of production volumes of metal oxide and carbon ENMs ).

• Center for Nanotechnology in Society at ASU (r isk p erce ption and p ublic p olicy ).

• Risk Assessment for Manufactured Nanoparticles Used in Consumer Products , o r RA M NUC (a n EPA grant assessing r isk associated with zinc oxide, silver, and cerium oxide nanoparticles in consumer products ).

• Empa (l ife c ycle assessment; r elease and e xposure m odeling ).

4. Evaluation and characterization of the f ate , transformation

, and treatment of ENMs in industrial wastewaters

The transformation, fate , and treatment of nanomaterials in industrial wastewaters have not been studied

. However, researchers have studied nanomaterial fate and treatment performance to some extent in municipal WWTPs in the U

. S

. and Switzerland

. Common treatment technologies employed in WWTPs, such as activated sludge, settling

, and filtration, are effective at removing nanomaterials from the wastewater, although the nanomaterials likely partition to the biosolids and may impact its beneficial use

. However, the applicability of th e research on municipal wastewater to industrial w astewater is unknown. Nanomaterial react ions and transform ations may vary depending on the aqu eous environment

, and industrial wastewater tends to have higher concentrations and varieties of constituents than either municipal
wastewater or the ambient envi ronment

. In addition, i ndustrial wastewater quality varies greatly between point source categories and industrial processes.Memorandum January 23, 2015 Page 24

ERG did not identify any organizations currently investigating ENMs in industrial
wastewater ; however , t he following organization s are investigat ing nanomaterial s in municipal WWTP s :

• ASU (o ccurrence and removal of TiO 2 in full

- scale WWTP; s ilver and fullerene s in simulated wastewater treatment processes ).

• Eawag (s ilver and g old ENM transformation and removal in activated sludge
processes ).

5. M ethods to distinguish between naturally occurring and engineered nanomaterials in aqueous media

Once detection methods are established, distinguishing between engineered and naturally occurring nanomaterials will be critical for monitoring a ctivities

, because concentrations of naturally occurring and incidental nanomaterials generally far exceed potential release s of EN M s into the environment ( Hochella, 2013 ; Wiesner et al., 2009 )

. The ability to distinguish engineered and natural nanomaterials will allow for identifying and targeting potential releases of ENMs and quantifying the associated risks and hazards. In addition, background levels of naturally occurring nanomaterials and na nomaterials that are incidentally generated during manufacturing as a result of chemical transformations may need to be considered as part of any future potential regulatory structure for industrial discharges of ENMs

.

9. R EFERENCES

1. Ali

- Boucetta, H., Nunes, A., Sainz, R., Herrero, M. A., Tian, B., Prato, M., Bianco, A., & Kostarelos, K. 2013. Asbestos

- like pathogenicity of long carbon nanotubes alleviated by chemical functionalization. Angewandte Chemie International Edition . 52 (8): 2274

- 2278. (February 18). www.dx.doi.org/10.1002/anie.201207664

.
2. Alloy, M. & Roberts, A. 2012. Photo

- enhanced toxicity of nano

- titanium dioxide (anatase) on freshwater zooplankton . Presented at the Society of Environmental Toxicology and Chemistry North America (SETAC) 33rd Annual Meeting, Long Beach, California. Available online at: http:// longbeach.setac.org/sites/default/files/SETAC

abstract

- book

- 2012.pdf

.
3. Arnaout, C. L. & Gunsch, C. K. 2012. Impacts of silver nanoparticle coating on the nitrification potential of nitrosomonas europaea. Environmental Science & Technology

. 46 (10): 5387

- 5395. (May 15). www.dx.doi.org/10.1021/es204540z

.
4. Auffan, M., Rose, J., Bottero, J.

- Y., Lowry, G. V., Jolivet, J.

- P., & Wiesner, M. R. 2009. Towards a definition of inorganic nanoparticles from an environmental, health and safety perspective. Nature Nanotechnology . 4: 634

- 641. www.dx.doi.org/10.1038/nnano.2009.24 2

.
5. Badireddy, A. R., Wiesner, M. R., & Liu, J. 2012. Detection, characterization, and abundance of engineered nanoparticles in complex waters by hyperspectral imagery with enhanced darkfield microscopy. Environmental Science & Technology . 46 (18): 100 81

- 10088. (2012/09/18). www.dx.doi.org/10.1021/es204140s

.Memorandum January 23, 2015 Page 25

6. Bullis, K. 2013. Quantum Dots Get Commercial Debut in More Colorful Sony TVs. MIT Technology Review. Available online at: http://www.technologyreview.com/news/509801/quantum

- dots

- get

- commercial

- debut

- in

more

- colorful

- sony

- tvs/

.

7. Cardinale, B. J., Bier, R., & Kwan, C. 2012. Effects of TiO 2 nanoparticles on the growth and metabolism of three species of freshwater algae. Journal of Nanoparticle Research

. 14 (8): 1

- 8. (July 14). www.dx.doi.org/10.1007/s11051

- 0 12

- 0913

- 6

.
8. Chae, S. R., Therezien, M., Budarz, J. F., Wessel, L., Lin, S. H., Xiao, Y., & Wiesner, M. R. 2011. Comparison of the photosensitivity and bacterial toxicity of spherical and tubular fullerenes of variable aggregate size. Journal of Nanopar ticle Research . 13 (10): 5121

- 5127. (July 15). www.dx.doi.org/10.1007/s11051

- 011

- 0492

- y

.
9. Colman, B. P., Wang, S.

- Y., Auffan, M., Wiesner, M. R., & Bernhardt, E. S. 2012. Antimicrobial eff ects of commercial silver nanoparticles are attenuated in natural streamwater and sediment. Ecotoxicology . 21 (7): 1867

- 1877. (October). www.dx.doi.org/10.1007/s10646

- 012

- 0920

- 5

.
10. Colman, B. P., Arnaout, C. L., Anciaux, S., Gunsch, C. K., Hochella, M. F., Kim, B., Lowry, G. V., McGill, B. M., Reinsch, B. C., Richardson, C. J., Unrine, J. M., Wright, J. P., Yin, L., & Bernhardt, E. S. 2013. Low concentrations of silver nanoparticles in bios olids cause adverse ecosystem responses under realistic field scenario. PLoS ONE . 8 (2): e57189. (February 27). www.dx.doi.org/10.1371/journal.pone.0057189

.
11. Dale, A. L., Lowry, G. V., & Casman, E. A. 2013. Modeling nanosilver transformations in freshwater sediments. Environmental Science & Technology . 47 (22): 12920

- 12928. (November 19). www.dx.doi.org/10.1021/es402341t

.
12. Dav id, R. M. 2013. Measuring engineered nanomaterials in the environment: A consortium view of how to address the problem. Environmental Engineering Science . 30 (3): 97

- 100. www.dx.doi.org/10.1089/ee s.2012.0327

.
13. Doolette, C. L., McLaughlin, M. J., Kirby, J. K., Batstone, D. J., Harris, H. H., Ge, H., & Cornelis, G. 2013. Transformation of PVP coated silver nanoparticles in a simulated wastewater treatment process and the effect on microbial communities. Chemistry Central Journal . 7 (1): 46. (March 4). www.dx.doi.org/10.1186/1752

- 153X

- 7

- 46

.
14. Eckelman, M. J., Mauter, M. S., Isaacs, J. A., & Elimelech, M. 2012. New perspectives on nanomaterial aquatic ecotoxicity: Production impacts exceed direct exposure impacts for carbon nanotoubes. Enviro nmental Science & Technology . 46 (5): 2902

- 2910. (2012/03/06). www.dx.doi.org/10.1021/es203409a

.
15. ERG. 2008. Eastern Research Group, Inc. Sampling and Analysis of Nanomaterials in the Environment : A State

- of

- the

- Science Review [Final Report] . Chantilly, VA. (August 29).

16. ERG. 2013. Eastern Research Group, Inc. Environmental Engineering Support for Clean Water Regulations Programmatic Quality Assurance Project Plan (PQAPP, Rev. 1, Approved Oct ober 20, 2013) . Chantilly, VA.Memorandum January 23, 2015 Page 26

17. Fabrega, J., Luoma, S. N., Tyler, C. R., Galloway, T. S., & Lead, J. R. 2011. Silver nanoparticles: Behaviour and effects in the aquatic environment. Environment International . 37 (2): 517

- 531. (February). www.dx.doi.org/10.1016/j.envint.2010.10.012

.
18. Fischer, J., Hoque, E., Metcalfe, C. D., & Hintelmann, H. 2012. A comparison of passive sampling devices for dissolved and nanoform silver in the aquat ic environment . Presented at the Society of Environmental Toxicology and Chemistry North America (SETAC) 33rd Annual Meeting, Long Beach, California. Available online at: http://longbeach.setac.org/sites/default/files/SETAC

- abstract

- book

- 2012.pdf

.
19. Gavankar, S., Suh, S., & Keller, A. 2012. Life cycle assessment at nanoscale: Review and recommendations. The International Journal of Life Cycle Assessment . 17 (3): 2 95

- 303. (March 1). www.dx.doi.org/10.1007/s11367

- 011

- 0368

- 5

.
20. Gottschalk, F., Sonderer, T., Scholz, R. W., & Nowack, B. 2009. Modeled environmental concentrations of engineered nanomateri als (TiO 2 , ZnO, Ag, CNT, fullerenes) for different regions. Environmental Science & Technology . 43 (24): 9216

- 9222. (December 15). www.dx.doi.org/10.1021/es9015553

.
21. Gottschalk, F. & Nowack, B. 2 011. The release of engineered nanomaterials to the environment. Journal of Environmental Monitoring . 13 (5): 1145

- 1155. www.dx.doi.org/10.1039/C0EM00547A

.
22. Healy, M. L., Dahlben, L. J., & Isaac s, J. A. 2008. Environmental assessment of single

walled carbon nanotube processes. Journal of Industrial Ecology . 12 (3): 376

- 393. www.dx.doi.org/10.1111/j.1530

- 9290.2008.00058.x

.
23. Heideman, W., Bar

- Ilan, O., Peterson, R., Pedersen, J., & Robert, H. 2012. TiO 2 nanoparticle exposure and illumination during zebrafish development: Mortality at parts per billion concentrations . Presented at the Society of Environmental Toxicology and Chemistry North America (SETAC) 33rd Annual Meeting, Long Beach, California. Available online at: http://longbeach.setac.org/sites/default/files/SETAC

- abstract

- boo k

2012.pdf

.
24. Hendren, C. O., Mesnard, X., Droge, J., & Wiesner, M. R. 2011. Estimating production data for five engineered nanomaterials as a basis for exposure assessment. Environmental Science & Technology . 45 (7): 2562

- 2569. (April 1). www.dx.doi.org/10.1021/es103300g

.
25. Hochella, M. F., Lower, S. K., Maurice, P. A., Penn, R. L., Sahai, N., Sparks, D. L., & Twining, B. S. 2008. Nanominerals, mineral nanoparticles, and earth systems. Science

. 319 (5870): 1631

- 1635. (March 21). www.dx.doi.org/10.1126/science.1141134

.
26. Hochella, M. F. 2013. Telephone Communication between Michael Hochella, Virginia Tech, and Eva Knoth and Kim Wag oner, Eastern Research Group, Inc., Re: Request for Information on Nanomaterials Research. (March 15).Memorandum January 23, 2015 Page 27

27. Kim, B., Park, C.

- S., Murayama, M., & Hochella, M. F. 2010. Discovery and characterization of silver sulfide nanoparticles in final sewage sludge pr oducts. Environmental Science & Technology . 44 (19): 7509

– 7514. (September 14). www.dx.doi.org/10.1021/es101565j

.
28. Kim, B., Murayama, M., Colman, B. P., & Hochella, M. F. 2012. Characterization a nd environmental implications of nano

- and larger TiO2 particles in sewage sludge, and soils amended with sewage sludge. Journal of Environmental Monitoring . 14 (4): 1128

- 1136. www.dx.doi.org/10.1039 /C2EM10809G

.
29. Latkoczy, C., Kagi, R., Fierz, M., Ritzmann, M., Gunther, D., & Boller, M. 2010. Development of a mobile fast

- screening laser

- induced breakdown detection (LIBD) system for field

- based measurements of nanometre sized particles in aqueous solutions. Journal of Environmental Monitoring . 12 (7): 1422

- 1429. www.dx.doi.org/10.1039/C002020F

.
30. Levard, C., Reinsch, B. C., Michel, F. M., Oumahi, C., Lowry, G. V., & Brown, G. E. 2011. Sulfidation processes of PVP

- coated silver nanoparticles in aqueous solution: Impact on dissolution rate. Environmental Science & Technology . 45 (12): 5260

- 5266. (June 15). www.dx. doi.org/10.1021/es2007758

.
31. Levard, C., Hotze, E. M., Lowry, G. V., & Brown, G. E. 2012. Environmental transformations of silver nanoparticles: Impact on stability and toxicity. Environmental Science & Technology . (February). www.dx.doi.org/10.1021/es2037405

.
32. Liu, X., Chen, G., Keller, A. A., & Su, C. 2013. Effects of dominant material properties on the stability and transport of TiO 2 nanoparticles and carbon nanotubes in aquatic environments: from synthesis to fate. Environmental Science: Processes & Impacts . 15 (1): 169

- 189. www.dx.doi.org/10.1039/C2EM30625E

.
33. Lowry, G. V. , Espinasse, B. P., Badireddy, A. R., Richardson, C. J., Reinsch, B. C., Bryant, L. D., Bone, A. J., Deonarine, A., Chae, S., Therezien, M., Colman, B. P., Hsu

Kim, H., Bernhardt, E. S., Matson, C. W., & Wiesner, M. R. 2012a. Long

- term transformation and f ate of manufactured Ag nanoparticles in a simulated large scale freshwater emergent wetland. Environmental Science & Technology . 46 (13): 7027

- 7036. (April). www.dx.doi.org/10.1021/es204608d

.
34. Lo wry, G. V., Gregory, K. B., Apte, S. C., & Lead, J. R. 2012b. Transformations of nanomaterials in the environment. Environmental Science & Technology . 46 (13): 6893

- 6899. (July). www.dx.doi.org/10.102 1/es300839e

.
35. Ma, R., Levard, C., Judy, J. D., Unrine, J. M., Durenkamp, M., Martin, B., Jefferson, B., & Lowry, G. V. 2013. Fate of zinc oxide and silver nanoparticles in a pilot wastewater treatment plant and in processed biosolids. Environmental Sc ience & Technology . 48 (1): 104

– 112. (November 22). www.dx.doi.org/10.1021/es403646x

.
36. Madden, A. S., Hochella, M. F., & Luxton, T. P. 2006. Insights for size

- dependent reactivity of hematite nan omineral surfaces through Cu 2+ sorption. Geochimica etMemorandum January 23, 2015 Page 28

Cosmochimica Acta . 70 4095

- 4104. (August 15). www.dx.doi.org/10.1016/j.gca.2006.06.1366

.
37. Mahendra, S., Zhu, H., Colvin, V. L., & A lvarez, P. J. 2008. Quantum Dot Weathering Results in Microbial Toxicity. Environmental Science & Technology . 42 (24): 9424

- 9430. (2008/12/15). www.dx.doi.org/10.1021/es8023385

.
38. Mueller, N. C. & Nowack, B. 2008. Exposure modeling of engineered nanoparticles in the environment. Environmental Science & Technology . 42 (12): 4447

- 4453. (June 1). www.dx.doi.org/10.1021/es7029637

.
39. Mulfinger, L., Solomon, S. D., Bahadory, M., Jeyarajasingam, A. V., Rutkowsky, S. A., & Boritz, C. 2007. Synthesis and study of silver nanoparticles. Journal of Chemical Education . 84 (2): 322. (February). Available online at: http://www.qi.fcen.uba.ar/materias/cqi/2011/infosuplementaria/practicas/practica2/Ag%2 0npartics%20Solomon%202007.pdf

.
40. Musee, N. 2011. Nanowastes and the env ironment: Potential new waste management paradigm. Environment International . 37 (1): 112

- 128. (January). www.dx.doi.org/10.1016/j.envint.2010.08.005

.
41. NIOSH. 2013. U.S. Department of Health and Human Services National Institute for Occupational Safety and Health DHHS (NIOSH). Current strategies for engineering controls in nanomaterial production and downstream handling processes . Cincinnati, OH. (Novembe r). DHHS (NIOSH) Publication No. 2014

– 102.

42. NNI. 2013a. NSI: Nanotechnology for sensors and sensors for nanotechnology: Improving and protecting health, safety, and the environment. Available online at: h ttp://www.nano.gov/NSISensors . Accessed: December 12, 2013.

43. NNI. 2013b. National Nanotechnology Initiative. Standards for nanotechnology. Available online at: http://nano.gov/you/standards . Accessed: Decem ber 12, 2013.

44. NNI. 2013c. National Nanotechnology Initiative. About the NNI. Available online at: http://nano.gov/about

- nni . Accessed: December 12, 2013.

45. Nowack, B., Krug, H. F., & Height, M. 2011. 120 ye ars of nanosilver history: Implications for policy makers. Environmental Science & Technology . 45 (4): 1177

- 1183. (February 15). www.dx.doi.org/10.1021/es103316q

.
46. NSET. 2014. National Nanotechno logy Initiative Strategic Plan . (February). Available online at: http://www.nano.gov/sites/default/files/pub_resource/2014_nni_strategic_plan.pdf

.
47. OECD. 2012. Organisation for Economic Co

- operation and Development. Guidance on Sample Preparation and Dosimetry for the Safety Testing of Manufactured Nanomaterials. Series on the Safety of Manufactured Nanomaterials . (December 18). Available online at:Memorandum January 23, 2015 Page 29

http://search.oecd.org/officialdocuments/displaydocumentpdf/?cote=env/jm/mono(2012) 40&doclanguage=en

.
48. OSHA. 2013. U.S. Department of Labor O ccupational Saftey and Health Administration. OSHA fact sheet: Working safely with nanomaterials . (April). Available online at: https:// www.osha.gov/Publications/OSHA_FS

- 3634.pdf

.
49. Pete rsen, E. J., Zhang, L., Mattison, N. T., O’Carroll, D. M., Whelton, A. J., Uddin, N., Nguyen, T., Huang, Q., Henry, T. B., Holbrook, R. D., & Chen, K. L. 2011. Potential release pathways, environmental fate, and ecological risks of carbon nanotubes. Enviro nmental Science & Technology . 45 (23): 9837

- 9856. (December 1). www.dx.doi.org/10.1021/es201579y

.
50. Plata, D. L., Hart, A. J., Reddy, C. M., & Gschwend, P. M. 2009. Early evaluation of potential e nvironmental impacts of carbon nanotube synthesis by chemical vapor deposition. Environmental Science & Technology . 43 (21): 8367

- 8373. (November 1). www.dx.doi.org/10.1021/es901626p

.
51. Project on Emerging Nanotechnologies. 2014. Consumer Products Inventory. Available online at: http://www.nanotechproject.org/cpi . Accessed: June 2, 2014.

52. Rezić, I. 2011. Determination of engineered nanoparticles on textiles and in textile
wastewaters. TrAC Trends in Analytical Chemistry . 30 (7): 1159

- 1167. www.dx.doi.org/10.1016/j.trac.2011.02 .017

.
53. Robichaud, C. O., Uyar, A. E., Darby, M. R., Zucker, L. G., & Wiesner, M. R. 2009. Estimates of upper bounds and trends in nano

- TiO 2 production as a basis for exposure
assessment. Environmental Science & Technology . 43 (12): 4227

- 4233. (May 15)

. www.dx.doi.org/10.1021/es8032549

.
54. Rottman, J., Platt, L. C., Sierra

- Alvarez, R., & Shadman, F. 2013. Removal of TiO 2 nanoparticles by porous media: Effect of filtration media and water chemist ry. Chemical Engineering Journal . 217 (1): 212

- 220. (February). www.dx.doi.org/10.1016/j.cej.2012.11.117

.
55. Sadik, W., Du, N., & Okello, V. 2012. Flexible poly(amic) acid membrane captures

, isolates & simultaneously detects engineered nanoparticles . Presented at the Society of Environmental Toxicology and Chemistry North America (SETAC) 33rd Annual Meeting, Long Beach, California. Available online at: http://longbeach.setac.org/sites/default/files/SETAC

- abstract

- book

- 2012.pdf

.
56. SETAC. 2012. Society of Environmental Toxicology and Chemistry. SETAC North America 33rd Annual Meeting Abstract Book . Lo ng Beach, California. Available online
at: http://longbeach.setac.org/sites/default/files/SETAC

- abstract

- book

- 2012.pdf

.
57. U.S. EPA. 2010a. Characterizing Concent rations and Size Distributions of Metal

Containing Nanoparticles in Waste Water . Washington, D.C. EPA/600/R

- 10/117.Memorandum January 23, 2015 Page 30

58. U.S. EPA. 2010b. Nanomaterial Case Studies: Nanoscale Titanium Dioxide in Water Treatment and in Topical Sunscreen . Washington, D.C. EPA/600/R

- 09/057F.

59. U.S. EPA. 2011a. Nanotechnology basic information. Available online at: http://epa.gov/ncer/nano/questions/ . Accessed: May 24, 2013.

60. U.S. EPA. 2011b. Scree ning methods for metal

- containing nanoparticles in water

. Washington, DC. EPA/600/R

- 11/096.

61. U.S. EPA. 2011c. Final 2010 Effluent Guidelines Program Plan . Washington, D.C. EPA

HQ

- OW

- 2008

- 0517

- 0575.

62. U.S. EPA. 2013a. Significant New Use Rules on C ertain Chemical Substances. Washington, D.C. (June 26). EPA

- HQ

- OPPT

- 2010

- 0279

- 0134.

63. U.S. EPA. 2013b. Nanomaterials EPA is assessing. Available online at: http://www.epa.gov/nanoscience/quickfinder/nanomaterials.htm#carnan . Accessed: December 11, 2013.

64. U.S. EPA. 2013c. Nanoscale Materials Stewardship Program. Available online at: http://epa.gov/op pt/nano/stewardship.htm . Accessed: May 20, 2013.

65. U.S. EPA. 2013d. Response to Comments for the Final 2010 Effluent Guidelines Program Plan . Washington, D.C. EPA

- HQ

- OW

- 2010

- 0824

- 0196.

66. U.S. EPA. 2013e. Significant New Use Rules on Certain Chemical Substances

. Washington, D.C. (August 7). EPA

- HQ

- OPPT

- 2013

- 0399

- 0001.

67. Unrine, J. M., Bertsch, P., Tsyusko, O., Shoults

- Wilson, W. A., Lowry, G. V., Colman, B. P., & Bernhardt, E. S. 2012. Fate and effects of silver nanoparticles in terrestrial enviro nments . Presented at the Society of Environmental Toxicology and Chemistry North America (SETAC) 33rd Annual Meeting, Long Beach, California. Available online at: h ttp://longbeach.setac.org/sites/default/files/SETAC

- abstract

- book

- 2012.pdf

.
68. Westerhoff, P., Song, G., Hristovski, K., & Kiser, M. A. 2011. Occurrence and removal of titanium at full scale wastewater treatment plants: implications for TiO 2 nanomaterial s. Journal of Environmental Monitoring . 13 (5): 1195

- 1203. (May). www.dx.doi.org/10.1039/c1em10017c

.
69. Westerhoff, P. K., Kiser, M. A., & Hristovski, K. 2013. Nanomaterial removal and transformat ion during biological wastewater treatment. Environmental Engineering Science . 30 (3): 109

- 117. www.dx.doi.org/10.1089/ees.2012.0340

.
70. Wiesner, M. R., Lowry, G. V., Jones, K. L., Hochella, M. F., Di Giulio, R. T., Casman, E., & Bernhardt, E. S. 2009. Decreasing uncertainties in assessing environmental exposure, risk, and ecological implications of nanomaterials. Environmental Science & Technology . 43 (17): 6458

- 6462. (September 1). www.dx.doi.org/10.1021/es803621k

.Memorandum January 23, 2015 Page 31

71. Wiesner, M. R., Lowry, G. V., Casman, E., Bertsch, P. M., Matson, C. W., Di Giulio, R. T., Liu, J., & Hochella, M. F. 2011. Meditations on the ubiquity and mutability of n ano

sized materials in the environment. ACS Nano . 5 (11): 8466

- 8470. (November 22). www.dx.doi.org/10.1021/nn204118p

.
72. Wiesner, M. R. 2013. Telephone Communication Between Mark Wiesner, Duke Univ ersity, and Eva Knoth and Kim Wagoner, Eastern Research Group, Inc., Re: Request for Information on Nanomaterials Research. (March 13).

73. Windler, L., Lorenz, C., von Goetz, N., Hungerbuhler, K., Amberg, M., Heuberger, M., & Nowack, B. 2012. Release of titanium dioxide from textiles during washing. Environmental Science & Technology . 46 (15): 8181

- 8188. (August 7). www.dx.doi.org/10.1021/es301633b

.
74. Woo, M. 2013. A quantum dot shows its true colors. American Physical Society. Available online at: http://link.aps.org/doi/10.1103/Physics.6.73

.
75. Yang, X., Gondikas, A. P., Marinakos, S. M., Auffan, M., Liu, J., Hsu

- Kim, H., & Meyer, J. N. 2012. Mechanism of silver nanoparticle toxicity is dependent on dissolved silver and surface coating in Caenorhabditis elegans. Environmental Science & Technology . 46 (2): 1119

- 1127. (January 17). www.dx.doi.org/10.1021/es202417t

.

76. Yong, K.

- T., Law, W.

- C., Hu, R., Ye, L., Liu, L., Swihart, M. T., & Prasad, P. N. 2013. Nanotoxicity assessment of quantum dots: from cellular to primate studies. Chemica l Society Reviews . 42 (3): 1236

- 1250. www.dx.doi.org/10.1039/C2CS35392J

.

77. Zhang, Y., Chen, Y., Westerhoff, P., Hristovski, K., & Crittenden, J. C. 2008. Stability of commercial metal oxide nanop articles in water. Water Research . 42 (8

- 9): 2204

- 2212. www.dx.doi.org/10.1016/j.watres.2007.11.036

.Memorandum January 23, 2015 Page 32

A PPENDIX A K EY Q UESTIONS FOR D ISCUSSIONS WITH R ESEARCHERS

1. Are there analytical techniques/methods available to detect nanomaterials in industrial wastewater?

a. Are there methods sensitive enough to detect the nanomaterials at typical levels present?

2. Are nanomaterials toxic to human health or aquatic ecosystems?

a. Any studies from demonstrated exposure to nanomaterials in industrial wastewater? b. Are studies demonstrating toxicity in vivo or in vitro, any observing effects in the natural environment?

3. Have there been any studies on the presence of nanomaterials in industrial wast ewater?

a. Where should we focus our efforts, primary manufacturers or the industries that use nanomaterials in development of secondary products? Which would have the greatest wastewater discharge impact? b. Are there certain industries or types of nanomaterial s that would typically have a wastewater discharge release?

Are there technologies that can treat nanomaterials in wastewater discharge? Are any conventional technologies effective at treating nanomaterials?Memorandum January 23 , 2015 Page 33

A PPENDIX B 2 U.S. C OMPANY I NFORMATION FOR P RIMARY P RODUCERS OF E NGINEERED N ANOMATERIALS
Adapted from (Hendren et al., 2011 ) S upplemental I nformatio n

.

Table B

- 1

. Nano

- TiO 2 Company Information

Company Product Website Other Sources Altair Nano Nano

- TiO 2 http:// www.altairnano.com U.S. Patent Number 6974566

, http://www.edgar

- online.com DuPont Several TiO 2 products including Dupont TS

- 6200, fine powders that may include

nano

- TiO 2 http://www2.dupont.com/Titanium_Tech nologies/en_US/index.html http://www.sec.gov/Archives/edgar/data/30554/000104746910 000945/a2196441z10

- k.htm

, http://money.cnn.com/magazines/fortune/global500/2006/snap shots/451.html NanoAmor N ano

- TiO 2 http:// www.nanoamor.com http://www.139001.net/company.asp?id

- 535458 NanoGram N ano

- TiO 2

— http://www.linkedin.com/companies/nanogram

- corporation Sigma Aldrich 8 nano

- TiO 2 products: 6 nanopowders, 1 dispersion, and 1 paste http://www.sigmaaldrich.com/materials

science/material

- science

products.html?TablePage=16376794 Email techserv@sial.com

Sky Spring Nanomaterials 4 nano

- TiO 2 powders http://www.ssnano.com/inc/sdetail/316 http://www.globalspec.com/supplier/proficle/SkySpring_Nano materials

2 The tables in this appendix, adapted from the cited literature source, provide a snapshot of U.S. manufacturers of nanomateri als as identified through patents, company websites, and requests for information. ERG has not confirmed whether the companies list ed continue to manufacture ENMs

.Memorandum January 23 , 2015 Page 34

Table B

- 2

. Nano silver Company Information

Company Product Website Other Sources American BioTech Labs Nanosilver solutions

— wound care, supplements, etc. http://www.americanbiotechlabs.co m/ Blue Nano Inc. Nanosilver particles 100 nm http://www.bluenanoinc.com http://www.linkedin.com/companies/blue

nano?trk=co_search_results&goback=.cps_1271784864897_1 NanoAmor Polymer

- coated nan o powder http:// www.nanoamor.com http://www.139001.net/company.asp?id=535458 NanoHorizons Inc. SmartSilverTM http:// www.nanohorizons.com http://www.linkedin.com/profile?viewProfile=&key=6385716 3&authToken=ZvLv&authType=OUT_OF_NETWORK&loca le=en_US&srchindex=38pvs=ps&goback=. fps_*1_*1_*1_*1_ *1_*1_NanoHorizons_C_Y_*1_*1_*1_false_1_R_true_N%2 CG%2CI%2CED%2CFG%2CL%2CDR%2CCC%2CPC_*2_* 2_*2_*2_*2_*2_*2_*2_*2_*2_*2_*2_*2_*2_*2_*2_*2_*2_ *2 NanoMas Technologies, Inc. NanoSilverTM htt p://www.nanomastech.com/index. html http://www.linkedin.com/companies/363757

Quantum Sphere QSI

- Nano silver nanopowder http://www.qsinano.com/about.ph p http://www.qsinano.com/products.php Sigma Aldrich 2 silver nanopowders http:// www.sigmaaldrich.com http://www.sigmaaldrich.com/catalog/Lookup.do?N5=All&N3 =mode+matchpartialmax&N4=silver+nano&D7=0&D10=silve r+nano&N1=S_ID&ST=RS&N25=0&F=PR Silver Nanotechnologies, Inc. NanoSilver Solutions

— http://snti.en.ec21.com/Memorandum January 23 , 2015 Page 35

Table B

- 3

. CNT Company Information

Company Product Website Other Info Sources Alfa Aesar 11 types of nanotubes http://www.alfa.com/en/GP140W.p
gm http://www.manta.com/c/mtkhc1b/alfa

- aesar

American Elements 4 types of CNTs, some single, some double, and some mul ti

walled http://www.americanelements.com/ nanotech.htm http://www.manta.com/c/mmcmm64/american

- elements

corporation

C arbon Solutions, Inc. 7 SWCNT products at various purities and solubilities http://carbonsolution.com/ http://www.manta.com/c/mm2jknd/carbon

- solu tions

- inc

Catalytic Materials LLC 1 grade of MWCNTs http://www.catalyticmaterials.com/ http://www.azonano.com/Suppliers.asp?SupplierID=674 http://www.catalyticmaterials.com/patentportfolio.html Cnano Technology Single, double, and multi

- walled CNTs http://www.cnanotechnology.com/e n/pro.html http://www.pangaeaventures.com/news/41

- cnano

technology

- commissions

- worlds

- largest

- carbon

- nanotube

manufacturing

- plant

- with

- a

- capacity

- of

- 500

- tons

- per

- year Helix Material Solutions 2 types of SWCNTs, 1 DWCNT, and 3 types of MWCNTs http://www.helixmaterial.com/prod uct.html —
Hyperion Catalysis Hyperion FIBRIL MWCNTs http://www.hyperioncatalysis.com/ emerging2.htm http://www.manta.com/c/mm3ht3h/hyperion

- catalysis

- intl http://investing.businessweek .com/research/stocks/private/s napshop.asp?privcapId=29658 Mer Corporation Various single, double, and multi

walled CNTs http://www.mercorp.com/products2 .htm http://www.linkedin.com/companies/mer

- corporation

MicroTech Nano Various single, double, and multi

walled CNTs http://www.microtechnano.com/

—

Nano

- C SWCNTS in 2 purity grades http://nano

- c.com/nanoprod.html http://www.spoke.com/info/c5ZZAgi/Nano

- CInc Nanocs, Inc. SWCNTs and MWCNTs with a variety of diameters http://www.nanocs.com/nanotube.h
tm http://dnb.powerprofiles.com/profile/931146919/NANOCS +INTERNATIONAL,+INC

- MALDEN

- MA N anoLab, Inc

. 6 varieties of single, double

, and multi

- walled CNTs http://www.nano

- lab.com/swnt

- apj

a.html http://www.manta.com/c/mmgjlkw/nanolab

- inc

Nanostructured & Amorphous Materials, Inc. Over 70 varieties of CNT s http://www.nanoamor.com/inc/pdet ail?v=1&pid=602 http://www.139001.net/company.asp?id=535458

NanoTechLabs MWCNTs with a variety of diameters http://www.nanotechlabs.com/pag e s/products/nanotubes.html http://www.manta.com/c/mtbzf4y/nanotechlabs

- inc

SES Research 8 types of MWCNTs, 2 types of SWCNTs, and 1 type of DWCNT http://sesres.com/Nanotubes.asp http://www.manta.com/c/mm6h4zs/ses

- research

Skyspring Nanomaterials 8 types of single and multi

- walled CNTs and many functionalized CNTs http://www.ssnano.com/inc/sdetail/ 869 http://www.globalspec.com/supplier/profile/SkySpringNan omaterialsMemorandum January 23 , 2015 Page 36

Table B

- 3

. CNT Company Information

Company Product Website Other Info Sources SouthWest Nanotec hnologies 4 types of SWCNT products and 1 specialty MWCNT product http://www.swentnano.com/ http://www.crunchbase.com/company/southwest

n anotechnologies http://www.linkedin.com/companies/southwest

nanotechnologies

- inc Unidym, now merged with CNI 3 purity grades of SWCNTs http://www.unidym.com/products/ materials.html http://www.hoovers.com/company/Unidym_Inc/rfjfyci

1.html Xintek, Inc

. , or “Applied Nanotechnologies” “Few

- wall” CNT s, DWCNTs

, and MWCNTs http://www.xintek.com/products/m aterials/index.htm http://www.manta.com/c/mm8z7g0/applie d

nanotechnologies

- inc DWCNT: double

- walled carbon nanotube MWCNT: multi

- walled carbon nanotube SWCNT: single

- walled carbon nanotube