### Ben Horenst e in Tri-TAC Chair East Bay Municipal Utility District 375 – 11 th 

### Street, MS702 Oakland, CA 94607 (510) 287-1846 bhorenst@ebmud.com

June 28, 20 10

Office of Pesticide Progr ams (OPP) Regulatory Public Docket (7502P) U.S. Enviro nmental Protection Agen cy (U.S. EPA) 1200 Pennsylvania Ave., NW. Washington, DC 20460–0001

RE: Nanosilver Antimicrobial Pesticide Products; Re gistration Ap plication (Docket Number EPA– HQ– O PP–2 010-0325)

The purpose of this let t e r is to com m ent on the application t o register na nosilver as an antimicrobial and pre s ervative additive. We are pleased t o have the opportunity to provide U.S. EPA information from our experi ence and scientific literat ure, with the goal of helping U.S. EPA ensure the environmental risk assessment s for nanosilver are complete and accurat e and informing U.S EPA’s risk management decision. Our comment s focus specifical ly on the environme n tal risks of silver discharges t o publicly-o wned wastewater treatment plants ( P OTWs).

Tri-TAC is a technica l a d visory committee representing the League of California Cities, Calif ornia Association of Sani tation Agencies, and California Water Environmen t Associat io n. We seek to improve the effectiveness and accountability of environmental progra m s that affect publicly owned treatment works in California by working with regulat ory agencies and intere st groups on treatment plant-related issues.

Tri-TAC me mbers are very concerned about the water qualit y impacts from the discharge of silver and n anosilver in particular int o our municipal wastewater systems. These concer ns have been express ed in our previous letters t o U.S. EPA and in letter s from our colleagues at the Bay Are a Clean Water Agencies (BACWA) and the National Association of Cle an Water Agencies (NACWA). We appreciated U.S. EPA’s decision to r egulate silver ion-generating product s like the Samsung “Silver Wash” washing machine. This decision recognized our concern s about the potential wa ter quality impacts of residential p e sticide uses—and affirmed U.S. EPA’s responsibility to regulate releases of pest i cidal silver into the environment.

Tri-TAC’s I n terest in Silver-Based Pesticides

Silver is hig h ly toxic to aquatic lif e at low concent rations, is p e rsistent, an d can bioaccumulate in some aquatic orga nisms, such as clams. D ue to concer ns about Vice Chair Natalie Sierra San Francisco Public

Utilities Commis s i on 1145 Market St re et, 5 th Fl oo r San Francisco, C A 94103 (415) 9 34-57 72

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a ter Co mmi tte e Co-C hairs Gail C h esler Central Cont ra C o sta

Sanitation District 5019 Imhoff Plac e Martinez, CA 94 553 (925) 2 29-72 94 gchesler@ccentralsan.org

Lorien Fo no Carollo Engineer s 2700 Y gnacio Va lley R oad, Suite 300 Walnut Creek, C A 94598 (925) 9 32-17 10 lfono@carollo.com

Air Co mmi ttee Chair Ja y Wi thers p o o n CH2M Hill 155 Grand Aven ue, Suite 1000 Oakland, CA 94 612 (510) 2 51-28 88 jay

. w i t herspoon @ch2m.com

Land Co mmi tte e Co-C hairs Greg Baatr up Fairfield-Suisun Sewer

Distr i ct 1010 Chad bourn e Road Fairfield, CA 94 534 (707) 4 28-91 62 gbaatrup @ fssd.com

Matt Ba o Los Angeles Count y Sanitation Districts 1955 Workman Mill Road Whittier, CA 906 01 (562) 6 99-74 11 e x t. 2809 mbao@lacsd.orgDocket No. EPA–HQ–OPP–2010-0325 June 28, 2010 Page 2

A technical advisory committee on POTW regulatory and policy issues bioaccumulation and the placing of strict silver effluent limits in discharge permits, POTWs have implemented pollution prevention programs to identify and reduce silver discharges to sanitary sewer systems. These programs have been very successful in reducing POTW influent and effluent silver concentrations. These programs have also reduced silver conc entrations in biosolids (sewage sludge), ensuring that silver will not limit options for biosolids reuse.

As discussed at length in the enclosed BACWA letter, the enclosed report by the Woodrow Wilson International Center for Scholars (Luoma 2008), and in enclosed scientific papers, ordinary use of silver-c ontaining pesticides releases silver to municipal wastewater treatment system s. Widespread use of household products that release silver particles into sani tary sewer systems could increase silver concentrations in POTW influents, effluents, and biosolids. If silver pesticide product use becomes common, wastewater s ilver discharges could reach levels not seen in the last two decades—and could hav e adverse impacts on our wastewater treatment process as well as on the quality of our effluent and biosolids.

POTWs are subject to National Pollutant Discharge Elimination System (NPDES) permits under the Clean Water Act. These permits include toxicity limits and may also include quantitative effluent limitations for silver. Exceeding these limitations has serious consequences, including monetary fines and penalties and the risk of citizen lawsuits. Under California law, our members are liable for daily Mandatory Minimum Penalties should violations of their discharge permits occur.

Nanosilver and POTWs

Available scientific information indicates that it will be important for the POTW discharge assessment to include a special assessment of the wastewater discharges from nanosilver products. Silver particle size and form (e.g., zeolite) may significantly alter the way silver-containing products affect POTWs. For example:

• The quantity and/or nature of silver discharged to POTWs may be affected by the small particle size and large surface area of nanosilver products as compared to other silver biocides . For example, Benn and Westerhoff (2008) found that for certain products, silver losses during washing were so large that most of the silver in these products would be washed into the municipal wastewater system during the products’ lifetimes. (A copy of this paper is enclosed.) Where small particles occur in products, the entire particle could be washed down the drain.

• Nanosilver particle may have extraordinary effects on POTW treatment

processes . In two related studies, Choi and Hu (2008) and Choi et al. (2008) found that silver particles less than 5 nanometers in diameter are uniquely toxic to nitrifying bacteria, which are critical to biological nutrient removal at POTWs. (Copies of both papers are enclosed).Docket No. EPA–HQ–OPP–2010-0325 June 28, 20 10 Page 3

A technica l adv isor y c o mmitte e on POT W regul ator y an d p o lic y issu es • Differing removal efficiencies . POT W s tend to be most efficient at removing larger particles from wastewater. Tiny particles a nd zeolite s may ha ve different pot ential to pass through POTWs than other forms of silver.

• Particle size is known to modify silver’s aquatic to xicity . For example, see Griffitt et al. 2008, enclo sed.

Widespread Use of Silver-Based Pesticides Is Not Sustainable

It is distressing to POTW s to observe the increasing prevalence of house hold products tha t use silver and other to xi c chemicals for gener al antimicrobial

purposes. POTWs are proud of our history of taking effect ive actions th at reduce discharges of toxic pollu tants to the env ironment . While POTWs have the authority to regulate industrial an d commercial sources o f silver and other toxic pollutants, we have little or no control o v er the discharge of pollutants from the thousand s of households we serve. Silver is a toxic metal that cannot degr ade in the e n vironment and is regist ered for use as a pestici de in numerous product s . To allow the unrestricted usage of pro ducts that in tenti onally r e lease silver into the environment would be an irresponsib l e neglect of the principle s of environmental sust ainability that should strongly influence U.S. EPA’s decisions.

Thank you for your consideration of our commen t s on the ap plication to r egister nanosilver as an antimicrobial and pr eserva tive additive. If you have any questions, please cont act Gail Chesler, at (925 ) 229-7294 or chesler.g a il@gmail.com.

Sincerely,

Ben Horenstein Tri-TAC Ch air

Enclosures:

1. Pla, M. Bay Area Clean Water Agencies (2009). Comment letter – petition for Rulemaking Requesting U.S. EPA Regulate Nanoscale Silver Produ cts as Pesticides. Letter to Nathanael R. Martin, U.S. EPA. Marc h 19.
2. Luoma, S. N. (2008). Silver Nanotechnologies a nd the Envir o n m ent: Ol d Proble m s or New Challenges? Woo d row Wilson Internationa l Center for Scholars, Pr oject on Emerging Nanotechnologie s . Publicat io n PEN 15. September.
3. Benn, T. M. and P. Westerhoff (2008). "Nanoparticle silver released into water from commercially available so ck fabrics." Environm en tal Science & Technology 42 (11): 4133-9 (publish ed correctio n is included ).
4. Blaser, S. A., M. Scheringer, et al. (2 008). “Estimation of cumulative aquatic exposure and risk due to silver: Contribution of n ano-function alized pla s tics and textiles. ” Science of the Total E n vironm ent 390 (2-3): 396-409.Docket No. EPA–HQ–OPP–2010-0325 June 28, 20 10 Page 4

5. Choi, O. and Z. Hu (2008). "Size de pendent and reactive oxygen specie s related nano silver toxicit y to nitrifying bacteria." Environm en tal Science & Technology 42 (12): 4583-8.
6. Choi, O., K. K. Deng, et al. (2008). “ The inhibitor y effects of silver nanoparticle s , silver ions, and silver chlo ride co lloids on micr obial growth.” Water Research 42 : 20 66-2074.
7. Griffitt, R. J., J. Luo, et al. (2008). "Effects of particle composit ion and species on t o xicity of me tallic nanom aterials in a quatic organ isms." Environm en tal Toxico l o g y & Che m i s try 27 (9): 1 972-8. 8. Pesticide Tr ansport to POTWs – conceptual model diagram and diagram of examples of direct and indirect path w ays betwe en pesticide uses and POTWs

Note: Enclosures 3 thro ugh 7 are co pyrighted materials that cannot be p o sted in the public d o cket. These have been subm itted via em ail to Heather Garvie. We request that U.S. EPA pr ovide these materials to all staff that are reviewing these

com m ents.

cc: Steve O w ens, Assistant Admini strator, Office of Preventing, Pe sticides, and T o x i c Substances Steven Bradbur y , Acting Dir ec tor, U.S. EPA Office of Pesticide Programs W illiam R. Di a m ond, Dir ector

, Field and E x t e rna l Affairs Di vision Jack Hous eng er, Director, Biolo g ica l an d Econom ic Anal ys i s Divisio n Lois R o ssi, Dir ector, Registrat i on Div isi on Joan H a rrig an- F a rrell y, Direct o r, Antimicrob i a ls Divis io n Bett y Shack l ef ord, Associate Director, Antim i crobi als Div isi on Norm Cook, Br anch C h ief, An timicrobi als Div ision Demson Fuller, U.S. EPA Offi ce of Pesticide Programs Peter Silva, Assistant Administra tor, U.S. EP A Office of Water Ephraim King, Director, U.S. EPA Office of Water, Office of Science and T e chnology James A. Hanlon, Director, U. S. EPA Office of Water, Offic e of Wastew at er Management Jared Blumenf eld, Administ rator, U.S. EPA Region 9 Alex is Strauss, Director, Wate r Division, U.S. EPA Region 9 Patti T enBrook , Life Scientist, U.S. EPA Region 9 S y e d Ali, Ca lifo r nia State W a ter Reso urces Contro l Board Nan Si ngh ase m ano n, Califor nia D epar tme n t of Pesticide R egu latio n Jeff W ong, Chi e f Scientist, Ca liforni a De par t m ent of T o xic Substanc es Co ntrol Kell y D. Mora n
, Urban Pestici des Pol l utio n P r eventi on Proj e c t Chris Hor n b a c k , Senior Dir ec tor, Regul ator y Affair s, Nation al Associ ation of Clea n W a ter Agenci e s Preeti Ghuma n
, Los Angel es Cou n t y Sa nitati on District Gail Ch esler, C entral C ontra C o sta Sanitar y District Lori en F o n o , Caroll o Eng i n eer s

A technica l adv isor y c o mmitte e on POT W regul ator y an d p o lic y issu es