C O N T E N T S

F e a t u r e A r t i c l e

T h e E c o l o g i c a lE f f e c t s o fN a n o m a t e r i a l s :A r e N e w S t r e s s o r sA s s o c i a t e d w i t hN e w T e c h n o l o g i e s ?

1–3

D e c i s i o n S u p p o r tT o o l s 3

N e w F a c e s 4

R e c e n t /U p c o m i n gP u b l i c a t i o n s 4

R e c e n t /U p c o m i n gC o n f e r e n c e s &P r e s e n t a t i o n s 5

F o r m o r ei n f o r m a t i o n ,c o n t a c t :

Paul D. Boehm, Ph.D.Principal Scientist and Group VicePresident, Environmental Group

(978) 461-1220

pboehm@exponent.com

www.exponent.com

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S P R I N G 2 0 0 8

A PUBLICATION OF EXPONENT’S ENVIRONMENTAL AND ECOSCIENCES PRACTICES

EnvironmentalPerspectives

The Ecological Effects ofNanomaterials: Are NewStressors Associated withNew Technologies?

L. Ziccardi, M. McArdle, Y. Lowney, J. Tsuji

The U.S. Environmental Protection Agency (EPA) definesnanotechnology as “research and technology developmentat the atomic, molecular, or macromolecular levels using alength scale of approximately one to one hundred nanometersin any dimension.” Nanomaterials include naturally-occurringparticles, those that are produced from combustion byproducts,and engineered or manufactured nanomaterials. Nanoparticles can be released to theenvironment from deliberate application (e.g., remedial applications), and from unintentionalor incidental releases, where they could come into contact with fish, wildlife, and plants.These organisms, termed “ecological receptors,” can potentially be exposed to nanoparticlesthrough inhalation, ingestion, movement across gills, passive transport, and cellular absorption.

The unique physicochemical properties of nanomaterials that make them beneficial in commercialapplications might also result in unexpected biological interactions. For example, their largesurface area relative to mass may translate to enhanced chemical binding capacity andreactivity. Another consideration in aquatic environments is that smaller particles will remainin suspension longer, which may affect their environmental transport, bioavailability, andtoxicity. On the other hand, nanoparticles’ high surface area and associated intermolecularforces may increase agglomeration and adherence to suspended matter or sediments, potentiallyreducing bioaccessibility.

Because of the unique properties of nanomaterials, concerns have been expressed that theireffects on aquatic and terrestrial organisms and ecosystems may be different from normal orfine-scale materials, although actual effects are likely complex and difficult to predict. Aquaticorganisms and terrestrial plants have been the focus of concern for environmental effects.

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For regulation of productscontaining substances such asnanoscale metallic compounds,the central question forecotoxicity is whether thesubstance is more toxic in nano-scale form than in the dissolvedform used in standardized testsand for which toxicity-based limitsare available. Studies for certainmetal oxides, zinc oxide forexample, have indicated that thenanoscale form is no more toxicto aquatic organisms or in vitrothan the same concentration ofsoluble zinc, although one studysuggested that nanoscale ironoxide particles were more toxicin vitro than soluble iron.

Emerging findings in aquatictoxicity studies usinginvertebrates, fish, and algaeindicate greater toxicityassociated with more reactivenanoscale substances such asengineered fullerenes, relativeto more inert substances such astitanium dioxide particles.Greater reactivity in nanoscale

form has also been investigatedfor anti-bacterial applications ofmetal oxides such as silver, zincoxide, and photo-catalytic formsof titanium dioxide. Such anti-bacterial effects, however, mayhave ecological implications.Therefore, the evaluation ofregulatory limits for such materialswill need to consider whethereffects from exposure to thenanoscale forms are any greaterthan effects from these metals inionic form or solution.

Nanoparticle ecotoxicity canvary with particle type, size, andattached functional groups.Nanoscale application appearsto increase the efficacy of somechemical formulations, such asmicronutrients or fertilizers, andmay therefore increase potentialreactivity and toxicity. Therelationship between toxicity andparticle size, however, iscomplicated. Greater reactivitymay also be beneficial; this isthe case for the effect ofnanoscale titanium dioxide onspinach seed germination andgrowth by affecting enzymesinvolved in nitrogen metabolism.In another example, one study

Studies specific to the aquaticand terrestrial effects ofnanomaterials in environmentallyrelevant species have been fewin comparison to mammalianstudies targeted primarily atunderstanding potential effectsto humans. The ecotoxicologicalstudies that are available focuson metal oxide particles, carbonnanotubes, and fullerenes,primarily in aquatic and planttoxicity tests. These initial studieshave also generally used highconcentrations to maximizeexposure and ensure that effectsare observed. Aquatic tests haveexamined the uptake ofnanoparticles by fish, filterfeeders (invertebrates), andalgae, and have providedevidence of toxicity or behavioralchanges associated withexposure. Studies on terrestrialspecies are limited toexperiments with plants (e.g.,root elongation, germination),primarily to investigate effectson crop species and the use ofnanomaterials in fertilizers.Some of these studies concludethat nanoparticles can be takenup by or produce effects in biota,and that dose-responserelationships and patterns ofrelative toxicity among types ofparticles are emerging.

Toxicity testing of nanomaterialsis not yet standardized andcertain challenges need to beaddressed. For example,preparation methods ofnanoparticle test suspensionsmay influence particle behaviorin solution and toxicity, therebyconfounding conclusions withregard to the toxicity of thenanoparticles themselves.Nearly all studies ofnanoparticles attempt tocounteract the natural tendencyof the particles to stick to thesides of the test vessel or

agglomerate and form largerparticles in solution by usingtechniques such as sonication,agitation, filtration, or additionof agents such as the solventtetrahydrofuran (THF). Forexample, some researchindicates that toxicity observedin aquatic exposure tests withC60 may in part be attributed toTHF itself or its more toxicbreakdown product(γ-butyrolactone) rather thanpurely to the effects of C60.Studies that removed much ofthe THF by extraction beforeexposures and have controls tocheck on the influence of addingTHF would more accuratelyindicate the toxicity of the testparticles.

Toxicity studies may not berepresentative of the real world.Studies that artificially producenanoparticles in solution, or invitro studies involving tissuecultures and isolated cells, mustalso be interpreted with caution.Such tests may indicate thepotential of nanoparticles tocause toxicity, but in the actualenvironment or within organisms,agglomeration would occur,thereby potentially reducing theirtransport, migration, and toxicity.Studies indicate that higherconcentrations of nanoparticlesin solution are associated withgreater agglomeration. Toxicityand mobility of nanoparticles inthe environment may thus, inpart, be self-limiting.

...the central question for ecotoxicity is whetherthe substance is more toxic in nano-scale form

than in the dissolved form used instandardized tests...

on daphnids, a freshwater filterfeeder, reported a hormetic effect(i.e., beneficial effect at lowexposures and an adverse effectat higher exposures) withexposure to single-walled carbonnanotubes; and similar patternshave been observed in plants.In addition, while several studiesindicate that particle size caninfluence biological effects, otherssuggest that toxicity is morerelated to changes innanoparticle surfacecharacteristics, and that smallersize does not always result in

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emerging nanotechnologies andnanoformulations, so thatresearch can target materials ofindustrial, and potentialenvironmental, importance.Several sources of funding toexpand these investigations arebeginning to emerge. Forexample, EPA is funding currentresearch under their grantprogram, Science to AchieveResults (STAR). STAR grants havebeen awarded to study theenvironmental and human healtheffects of engineerednanomaterials, andnanomaterials for use inenvironmental remediation. Formore information on this programand this research please go toes.epa.gov/ncer/nano/research/starawards.html.

greater toxicity. Size is likelyonly one of many characteristicsthat influences the environmentalfate and toxicity ofnanoparticles. In addition tosurface characteristics, otherfactors include chemistry andcrystal type, shape, andelectromagnetic properties.

Some of the properties ofnanomaterials that make themuseful in biotechnology andremedial applications may alsoresult in negative biologicaleffects at high doses. Forexample, fullerenes bind tolipids, which makes them usefulas drug carriers and for othertherapeutic applications whenfunctionalized; however, thissame binding characteristic andreactivity may have been thecause of adverse effects such asthe lipid peroxidation observedin the brains of fish exposed tohigh concentrations. Therefore,as the use of nanotechnologyincreases, it is important toimprove our understanding ofthe potential effects of thesematerials on biota, as well asincrease our knowledge to beable to better design future testson these materials.

While more research is clearlyneeded to understand thepotential for impacts onecological receptors andsystems, further guidance wouldbe useful regarding appropriatestudy design to ensure thatmeaningful conclusions can bedrawn from the investment infuture research. Severalimportant considerations haveemerged in our review of theavailable literature on ecologicaleffects. Each uniquenanomaterial (e.g., fullerenes,metal oxides, etc.) andderivatives of these materialsmay cause unique effects

because of differences in particlesize, shape, surface area,charge, solubility, and reactivity.Thus, the toxicity of eachnanomaterial needs to beconsidered independently.Studies should also be designedto allow for an understanding ofwhether the nano-characteristicsof the material are controllingtoxicity, or whether toxicity isassociated with the chemistry ofthe material being evaluated andis unrelated to particle size.Nanomaterials toxicityassessment should considerpotential effects resulting fromthe test-material preparationmethod (e.g., solvent vehicles orsonication used to maintainaquatic dispersion), the presenceof trace contaminants incommercial nano-products, and

Exponent scientists havepresented the results of theirreview of the ecological effectsof nanomaterials at theInternational Symposium onNanotechnology inEnvironmental Protection andPollution (ISNEPP 2007), andwill also be presenting an updateof their review at the NanoEcoconference in Monte Verità,Switzerland, March 2–7, 2008.For more information on theseconferences please visitwww.isnepp.org/ andwww.empa.ch/nanoECO/. Formore information on the subjectof nanomaterials, please contactJoyce Tsuji (tsujij@exponent.com),or Linda Ziccardi(lziccardi@exponent.com).

Exponent toxicologists have teamed with ourmaterial scientists to evaluate the potential risks

of products containing nanomaterials.

the potential influence ofnanoparticle agglomeration.The ability of nanoparticles toincrease the transport of otherchemicals via adsorption, andpotential influence onenvironmental fate, absorption,bioaccumulation, and biologicaleffects, should also beconsidered.

The existing body of researchfocuses on evaluation of relativelyfew types of nanoparticles,although the particles aregenerally those with the mostcurrent interest and applicationin consumer products (metalsand carbonaceous materials;www.nanotechproject.org/inventories/ consumer/analysis/).Future research could benefitfrom early identification of

Given the lack of standardmethodology for quantifyingnanoparticle exposure andlimitations in knowledge ontoxicity, a key focus formanufacturers should be onengineering processes andconsumer products thatencapsulate or limit liberation offree nanomaterials. Suchmaterials must also be durableand maintain their encapsulationeven during wear or weatheringof the product. Design of suchproducts or evaluations of theirwear behavior is within currentknowledge through the well-established discipline of materialsscience. In this way, Exponenttoxicologists have teamed withour material scientists to evaluatethe potential risks of productscontaining nanomaterials.

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New Faces

Ken CerretoFreshwater Ecologist,EcoSciences,Maynard, MA

Mr. Cerreto specializes inecological risk assessment andfield sampling. He has a wealthof field sampling experience inaquatic and terrestrial systems,has managed field samplingprograms, and is skilled atsampling both environmentalmedia and biota. Prior to joiningExponent, Mr. Cerreto was anAquatic Ecologist at ENSR, anEcologist at AMEC Earth &Environmental, and a ResearchAssistant at the University ofWyoming, Laramie. He wasalso an Assistant Scientist atMenzie-Cura & Associates, Inc,where he worked with a numberof his present colleagues atExponent. He holds master’sdegrees in Zoology andPhysiology from the Universityof Wyoming and a bachelor’sdegree in Biology and Pre-medfrom College of the Holy Cross.

Decision Support Tools for EnvironmentalRemediation and Restoration

Making decisions involves making trade-offs. If a course of actionis obvious, that doesn’t really require making a decision.Companies may face complex environmental decisions such as,“Should we remove all soils and sediments above 1 ppm anddig up forested wetland habitat areas in the process? Whatabout restoration options? Should we spend $500,000 restoringnon-contiguous areas of predominantly Phragmites, or is thatmoney better spent enhancing existing contiguous habitat areas?”

Every decision has an overall objective. For example, a companymay wish to maximize environmental benefits while minimizingcost, or more specifically, restore and augment a migratoryflyway at lowest cost. Lowest cost does not mean choosing theleast favorable option or shirking responsibility. It means allocatinglimited resources most efficiently. There is almost always uncertaintyabout the data (and/or models) that support a decision. “What

is the range of risks at our site? What are the consequencesof making a wrong decision (e.g., reality is not at the expectedvalue)?” If consequences are high, the importance of thedecision is high, too.

There are tools and analytical methods that can help sort outsuch complexities. Net environmental benefits analysis, relativerisk models, and a host of multi-criteria decision analysis toolsare all available to help evaluate multiple alternatives againsta consistent set of criteria. These tools are designed to integratedifferent kinds of information, analysis, and data that allcontribute to the decision-making process, including, for example,stakeholder acceptance, cost, risk, and impacts on habitat.Such tools make the decision process more transparent, byproviding an analytical framework for integrating disparateresults. How do you directly compare human health andecological risk, impact on habitat, and cost across competingalternatives when these all differ?

In the next newsletter, we will present some ideas, includingcase studies, on this topic.

Dr. Katherine (Johnson)PalmquistSenior Scientist,EcoSciences,Bellevue, WA

Dr. Palmquist has a stronginterdisciplinary background ininsect biology/physiology,toxicology, integrated pestmanagement, andcommunications. She hasdeveloped and publishedmethodology concerning thelaboratory maintenance andrearing of several stream insectspecies. Additionally, she hasexperience in performing loticand lentic benthic surveys, aswell as terrestrial insect fieldsampling. She holds a Ph.D. inToxicology from Oregon StateUniversity, and a B.S. inEntomology from WashingtonState University.

Brianne DuncanScientist,Environmental Sciences,Bellevue, WA

Ms. Duncan's background is inbiology and chemistry; she holdsa B.S. in biology with a minorin chemistry from SeattleUniversity.

Dr. Ann Michelle MorrisonAquatic Ecotoxicologist,Environmental Sciences,Maynard, MA

Dr. Morrison has a strong interestin data analysis, specifically inapplying statistical methods fromother fields (e.g., medical) toenvironmental data. Prior tojoining Exponent, Dr. Morrisonworked in the Benthic EcologyResearch Program in Bermudaassisting in the assessment ofBermuda’s near shoreenvironment by assessing thehealth of seagrass beds, coralreefs, and mangrove swamps.She holds an Sc.D. inEnvironmental Health fromHarvard University, an M.S. in

Environmental Health fromHarvard University, and a B.S.in Biology from Rhodes College.

Dr. Karen MurraySenior Scientist,Environmental Science,Maynard, MA

Dr. Murray studies the role ofbacteria in the environmentaltransport and fate of metals. Shehas experience in field samplingin marine, freshwater, and soilsystems. Her analytical expertiseincludes aerobic and anaerobicmicrobial culturing techniques,electrochemical andspectroscopic chemical analyses,and molecular biologicalmethods. Dr. Murray holds aPh.D. in Oceanography(Geochemistry) from the ScrippsInstitution of Oceanography,University of California, and aB.S. in EnvironmentalEngineering Science from theMassachusetts Institute ofTechnology.

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Ramón PierceGIS Analyst,EcoSciences,Bellevue, WA

Mr. Pierce specializes in thefunctionality of the ESRI ArcGISsuite software and its extensions,including spatial analysis (e.g.,short-path analysis, calculatingthe slope of an elevation, contourinterpretation, reclassifying andcreating cost data sets andweighting) and 3-D analysis(e.g., creating surface models,interpolating raster surfaces, andcreating features from surfaces).Mr. Pierce’s previous experienceis in traffic information. He holdsa B.A. in Urban Studies from theUniversity of Washington, anda Certificate in GeographicInformation Systems and SpatialModeling from the University ofWashington.

Dr. David J. RowanSenior ScientistEcoSciences,Boulder, CO

Dr. Rowan has more than 15years of experience inenvironmental consulting andresearch. He has expertise infood web, bioenergetics, andtransport and fate modeling ofradionuclides, metals, andorganics. Dr. Rowan has servedon advisory boards for IAEA,NCRP, and EPRI and hasmanaged many projects, bothlarge and small, for governmentand industry. He holds a Ph.D.in Biology from McGillUniversity, and an M.S. and B.S.in Geology, both from The OhioState University.

Recent/UpcomingPublications

Bessinger, B.A., Redding, B.,and Y.W. Lowney. 2007.Comments on “Release ofArsenic to the Environment fromCCA-Treated Wood. 2. Leachingand Speciation during Disposal.”Environ. Sci. Technol. 41(1):345–346.

Bigham, G., W. Chan,M. Dekermenjian, andA. Reza. Accepted. Indoorconcentrations of mercury vaporfollowing various spill scenarios.Environ. Foren.

Booth, P., N. Gard, S. Law,and R. Davis. 2007.Sustainability: Considerationsfor including eco-assets in acompany’s bottom line. ABASection of Environment, Energy,and Resources’ Climate Change,Sustainable Development, andEcosystems CommitteeNewsletter 11(1):7–11.

Chan, W.R., W. Nazaroff, P.Price, and A. Gadgil. 2007.Effectiveness of urban shelter-in-place–II: Residential districts.Atmos. Environ.41:7082–7095.

Goldstone, J.V., H.M.H.Goldstone, A.M. Morrison,A.M. Tarrant, S.E. Kern, B.R.Woodin, and J.J. Stegeman. Inpress. Cytochrome P450 1genes in early deuterostomes(tunicates and sea urchins) andvertebrates (chicken and frog): Origin and diversification of theCYP1 gene family. Molec. Biol.Evol. MBE Advance Accesspublished online October 4,2007.

Johnson, M., M. Korcz, K. vonStackelberg, and B. Hope. Inpreparation. Spatial analyticaltechniques for risk based decisionsupport systems. In: DecisionSupport Systems for Risk BasedManagement of ContaminatedSites. To be published bySpringer Verlag.

Kay, D.P., J.L. Newsted,M.T. BenKinney, T.J. Iannuzzi,and J.P. Giesy. (In press).Passaic River sediment interstitialwater Phase I toxicityidentification evaluation.Chemosphere.

Menzie, C., P. Booth, S.Law, and K. vonStackelberg. In preparation.Defining the problem. In: DSSsfor Inland and Coastal WatersManagement section, DecisionSupport Systems for Risk BasedManagement of ContaminatedSites. To be published bySpringer Verlag.

Murray, K.J., and B.M. Tebo.2007. Cr(III) is indirectlyoxidized by the Mn(II)-oxidizingbacterium Bacillus sp. strainSG-1. Environ. Sci. Technol.41:528–533.

Murray, K.J., S.M. Webb, J.R.Bargar, and B.M. Tebo. 2007.Indirect oxidation of Co(II) in thepresence of the marine Mn(II)-oxidizing bacterium Bacillus sp.strain SG-1. Appl. Environ.Microbiol. 73(21):6905–6909.

O’Reilly, K. 2007. Science,policy, and politics: The impactof the information quality act onrisk-based regulatory activity atthe EPA. Buffalo Environ. Law J.14(2):249–288.

Shock, S.S., B.A. Bessinger,Y.W. Lowney, and J.L. Clark. 2007. Assessment of thesolubility and bioaccessibility ofbarium and aluminum in soilsaffected by mine dust deposition.Environ. Sci. Technol. 41(13):4813–4820.

von Stackelberg, K., M.Nelson, B. Southworth, J. Cura,and T. Bridges. In press.Evaluation of sources ofuncertainty in a subset of riskassessments conducted for theU.S. Army. Integ. Assess.Environ. Manage.

Recent/UpcomingConferences andPresentations

IEEE Symposium on ProductCompliance EngineeringLongmont, CO.October 22–23, 2007

The influence of regulatorychanges on unique productdesigns.BenKinney, M., A. Arora, andJ. Swart.

23rd Annual InternationalConference on Soils,Sediments, and WaterUniversity of Massachusetts atAmherstOctober 15–18, 2007

Identification of natural gassources using geochemicalforensic tools.Boehm, P., T. Saba, andL. Benton.

About Exponent

Exponent is a leadingengineering and scientificconsulting firm dedicatedto providing solutions tocomplex problems.

Our environmentalconsulting servicesinclude:

• Ecological risk assessment• Environmental forensics• Environmental liability

management• Epidemiology• Human health risk

assessment/toxicology• Industrial hygiene/mold

investigations• Natural resource damage

assessment• Occupational medicine/

health• Product stewardship• Site investigation and

remediation.

Please visit our website,www.exponent.com, forinformation on all of ourconsulting services.

(888) 656-EXPOinfo@exponent.com18 regional and3 international offices

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North Atlantic Chapter ofSociety of EnvironmentalToxicology and ChemistryBristol, RIJune 13–15, 2007

Experience in applying theweight-of-evidence approach toaquatic sites contaminated withheavy metals.McArdle, M.E., C.A. Menzie,and S. Kane-Driscoll.

Methyl BromideAlternatives ConferenceSan Diego, CAOctober 29–November 1, 2007

Modeling and measurement ofmethyl bromide at foodprocessing facilities.Winegar, E., R. Reiss, andW.R. Chan.

International Symposiumon Nanotechnology inEnvironmental Protectionand PollutionFort Lauderdale, FLDecember 11–13 2007.

The ecological effects ofnanomaterials: Are newstressors associated with newtechnologies?”Ziccardi, L., M. McArdle,and Y. Lowney.