UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D.C. 20460
OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION

MEMORANDUM

Date: September 30,2013

SUBJECT: 2-(Decylthio) Ethanamine Hydrochloride (DTEA·HCI), Human Health and Ecological Preliminary Risk Assessment for Registration Review.

PC Code: 128963 DP Barcode: 410614, 410615 Decision No.: NA Registration Nos.: 464-619 Petition No(s).: NA Regulatory Action: Registration Review PRA Risk Assessment Type: Single chemical Case No.: 5029 TXRNo.:NA CAS No.: 36362-09-1 MRID Nos.: See PP 11, 12, 15, 38, 66, Tables 6 & 7 40 CFR: None

TO: Seiichi Murasaki, Chemical Review Manager ShaRon Carlisle, Acting Branch Chief Regulatory Management Branch 2 Antimicrobial Division (751 OP) Office of Pesticide Programs

FROM: William Hazel, Chemist

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Risk Assessment and Science Support Branch, Antimicrobial Division (751 OP) Office of Pesticide Programs

This document provides the preliminary risk assessment (PRA) conducted in support of registration review for DTEA-HCl (PC Code 128963) and DTEA (PC Code 128555). Information for this registration review case (5029) can be found in the public docket: EPA-HQOPP-2009-0336.Page 2 of 68 DTEA-HCl is registered for use to control bacterial, fungi and algae in industrial cooling towers. The PRA concludes no risks of concern for human health, but potential risks of concern for aquatic organisms from envir onmental releases of treated water from cooling towers.Page 3 of 68 

### Table of Contents
EXECUTIVE SUMMARY ............................................................................................................ 9 1.0 INTRODUCTION ................................................................................................................ 1 0 1.1 Case Overview ............................................................................................................... 1 0 1.2 Recent Regulatory Actions ............................................................................................. 10 1.3 Work Plan Modifications ............................................................................................... 11 2.0 ENVIRONMENTAL FATE ASSESSMENT ...................................................................... 11 3.0 HUMAN HEALTH RISK ASSESSMENT .......................................................................... 11 3.1 Human Health Hazard .................................................................................................... 11 3.1.1 Subchronic Toxicity ................................................................................................ 11 3.1.2 Developmental Toxicity.......................................................................................... 12 3.1.3 Mutagenicity ........................................................................................................... 12 3.1.4 Literature Search Results: ....................................................................................... 12 3.2 Dietary Assessment ........................................................................................................ 12 3.2.1 Dietary (Food) Exposure......................................................................................... 13 3.2.2 Drinking Water Exposure ....................................................................................... 13 3.3 Residential Assessment .................................................................................................. 14 3.4 Aggregate and Cumulative Exposure ............................................................................. 14 3.4.1 Aggregate Exposures .............................................................................................. 14 3.4.2 Cumulative Exposures ............................................................................................ 14 3.5 Occupational Assessment ............................................................................................... 14 3.6 Endocrine Disruptor Screen ing Program (EDSP) .......................................................... 15 4.0 ECOLOGICAL RISK ASSESSMENT ................................................................................ 16 4.1 Selected Ecological Toxicity Endpoints ........................................................................ 16 4.2 Summary of Exposures .................................................................................................. 17 4.2.1 Exposure of Aquatic Organisms to DTEA Downstream of Recirculating Cooling Towers 17 4.2.2 Analysis of Influence of Ratios of Plan t Flow to Stream Flow Distributions on Estimates of Numbers of Days per Year of Exceedance of COCs ....................................... 20 4.2.3 Estuarine/Marine Organisms .................................................................................. 20 4.2.4 Residue Levels in Aquatic Biota ............................................................................. 21 4.3 Risk Estimation .............................................................................................................. 21 4.4 Risks to Freshwater Fish a nd Aquatic Invertebrates. ..................................................... 22 4.4.2 Risks to Estuarine/Marine Organisms .................................................................... 24 4.4.3 Risks to Piscivorous Birds and Mammals .............................................................. 24 4.5 Risk Characterization ..................................................................................................... 24 4.5.1 Effect of Exposure Assumptions ............................................................................ 27 4.5.2 Uncertainties ........................................................................................................... 29 4.6 Endangered Species Assessment .................................................................................... 30 4.6.1 Action Area ............................................................................................................. 30 4.6.2 Taxonomic Groups Potentially at Risk ................................................................... 31 4.6.3 Listed Species Occurrence Associ ated with DTEA-HCl Use ................................ 31 5.0 SUMMARY OF RISKS ....................................................................................................... 32 APPENDIX A: Environmental Fate ............................................................................................. 33 APPENDIX B: Summary of Ec otoxicity Data for DTEA ........................................................... 37Page 4 of 68 APPENDIX C: Risk Estimation Methods ................................................................................... 47 APPENDIX D: Estimation of Potential Risks from Exposure of Aquatic Organisms to DTEA Downstream of Recircula ting Cooling Towers ............................................................................ 49 APPENDIX E: Estimated Sediment Exposure Concentrations ................................................... 65 APPENDIX F: Estimated Exposure C oncentrations in Aquatic Biota ........................................ 66

List of Tables Table 1 Ecological Effects Endpoints Selected for Assessing Risks from Use in Recirculating Cooling Systems ............................................................................................................... 16 Table 2 Application Rates from the Product Label ..................................................................... 18 Table 3 Application Rates from Label Adju sted for Density and DTEA Equivalents ................ 18 Table 4 Estimated Local Sediment Concentratio ns for With and Without Wastewater Treatment of Blowdown Water Prior to Discharge ............................................................................ 20 Table 5 Comparison of Number of Days pe r Year of Exceedance of COCs: Steam Electric Power Plants SIC Code versus Industriali zed POTWs SIC Code (2.8 kg/site/day and 93% Removal During WWT and 360 Days of Release per Year) ............................................ 20 Table 6. Physical/Chemical Characteristics and Environmental Fate Studies and Results .......... 33 Table 7 Ecotoxicity Data for DTEA·HCl and DTEA .................................................................. 38 Table 8 Freshwater Benthic Invertebrate Toxicity ...................................................................... 42 Table 9. Risk Presumption Categories ......................................................................................... 47 Table 10 High-End Scenario Estimates of Number of Days per Year of Exceedance of COCs for Aquatic Organisms Downstream of Large- Size Cooling Towers based on Facilities Belonging to the Steam Electric Power Plants SIC Code – Assumes No Treatment (No Removal) ...................................................................................................................... ..... 49 Table 11 High-End Scenario Estimates of Number of Days per Year of Exceedance of COCs for Aquatic Organisms Downstream of Moderate -Size Cooling Towers based on Facilities Belonging to the Steam Electric Power Plants SIC Code – Assumes no treatment and no removal ....................................................................................................................... ...... 50 Table 12 Average Case Scenario Estimates of Number of Days per Year of Exceedance of COCs for Aquatic Organisms Downstream of La rge-Size Cooling Towers based on Facilities Belonging to the Steam Electric Power Plants SIC Code – Assumes No Treatment and No Removal .............................................................................................. 50 Table 13 Average Case Scenario Estimates of Number of Days per Year of Exceedance of COCs for Aquatic Organisms Downstream of Moderate-Si ze Cooling Towers based on Facilities Belonging to the Steam Electric Power Plants SIC Code – Assumes No Treatment and No Removal .............................................................................................. 51 Table 14 High-End Scenario Estimates of Number of Days per Year of Exceedance of COCs for Aquatic Organisms Downstream of Large- Size Cooling Towers based on Facilities Belonging to the Steam Electric Power Plants SIC Code – Assumes 93 percent removal during WWT .................................................................................................................... . 51 Table 15 High-End Scenario Estimates of Number of Days per Year of Exceedance of COCs for Aquatic Organisms Downstream of Moderate -Size Cooling Towers based on Facilities Belonging to the Steam Electric Power Plants SIC Code – Assumes 93 percent removal during WWT .................................................................................................................... . 52Page 5 of 68 Table 16 Average Case Scenario Estimates of Nu mber of Days per Year of Exceedance of COCs for Aquatic Organisms Downstream of Larg e-Size Cooling Towers based on Facilities Belonging to the Steam Electric Power Plants SIC Code – Assumes 93 percent removal during WWT .................................................................................................................... . 52 Table 17 Average Case Scenario Estimates of Number of Days per Year of Exceedance of COCs for Aquatic Organisms Downstream of Moderate-Si ze Cooling Towers based on Facilities Belonging to the St eam Electric Power Plants SIC Code – Assumes 93 percent removal during WWT ....................................................................................................... 53 Table 18 High-End Scenario Estimates of Number of Days per Year of Exceedance of COCs for Aquatic Organisms Downstream of Large- Size Cooling Towers based on Facilities Belonging to the Steam Electric Power Plants SIC Code – Assumes No Treatment (No Removal) ...................................................................................................................... ..... 54 Table 19 High-End Scenario Estimates of Number of Days per Year of Exceedance of COCs for Aquatic Organisms Downstream of Moderate -Size Cooling Towers based on Facilities Belonging to the Steam Electric Power Plants SIC Code – Assumes no treatment and no removal ....................................................................................................................... ...... 54 Table 20 Average Case Scenario Estimates of Number of Days per Year of Exceedance of COCs for Aquatic Organisms Downstream of La rge-Size Cooling Towers based on Facilities Belonging to the Steam Electric Power Plants SIC Code – Assumes No Treatment and No Removal .............................................................................................. 55 Table 21 Average Case Scenario Estimates of Number of Days per Year of Exceedance of COCs for Aquatic Organisms Downstream of Moderate-Si ze Cooling Towers based on Facilities Belonging to the Steam Electric Power Plants SIC Code – Assumes No Treatment and No Removal .............................................................................................. 55 Table 22 High-End Scenario Estimates of Number of Days per Year of Exceedance of COCs for Aquatic Organisms Downstream of Large- Size Cooling Towers based on Facilities Belonging to the Steam Electric Power Plants SIC Code – Assumes 93 percent removal during WWT .................................................................................................................... . 56 Table 23 High-End Scenario Estimates of Number of Days per Year of Exceedance of COCs for Aquatic Organisms Downstream of Moderate -Size Cooling Towers based on Facilities Belonging to the Steam Electric Power Plants SIC Code – Assumes 93 percent removal during WWT .................................................................................................................... . 57 Table 24 Average Case Scenario Estimates of Number of Days per Year of Exceedance of COCs for Aquatic Organisms Downstream of La rge-Size Cooling Towers based on Facilities Belonging to the St eam Electric Power Plants SIC Code – Assumes 93 percent removal during WWT ....................................................................................................... 57 Table 25 Average Case Scenario Estimates of Number of Days per Year of Exceedance of COCs for Aquatic Organisms Downstream of Moderate-Si ze Cooling Towers based on Facilities Belonging to the St eam Electric Power Plants SIC Code – Assumes 93 percent removal during WWT ....................................................................................................... 58 Table 26 BCFBAF Program (v3.01) Re sults from EPI Suite (v4.11) ......................................... 67Page 6 of 68 TERMS, ABBREVIATIONS AND SYMBOLS

°C degrees Celsius % percent % w/w percent weight per weight μg microgram μg/g microgram per gram μg/L microgram per liter AD Antimicrobials Division Ae acid equivalents AI or ai active ingredient aPAD acute population adjusted dose ASRI activated sludge respiration inhibition

atm-m 3 /mole atmospheric pressure-cubic meter per mole BCF bioconcentration factor CaSO 4 calcium sulfate CaSO 3 calcium sulfite CAS Chemical Abstracts Service CCA chromated copper arsenate CFR Code of Federal Regulations CHO Chinese hamster ovary CMA Chemical Manufacturers Association CSF Confidential Statement of Formulation CO 2 carbon dioxide COC concentration-of-concern cPAD chronic population adjusted dose CS 2 carbon disulfide DCI data call-in
DTEA 2-(decylthio) ethanamine
EC 50 median (or 50 percent) effect concentration EC 05 5 percent effect concentration ECOTOX ECOTOXicology EDI estimated daily intake EDSP Endocrine Disruptor Screening Program EEC estimated environmental concentration E-FAST Exposure and Fate Assessment Screening Tool EP End-use product EPI Suite Estimation Program Interface Suite EPA Environmental Protection Agency FDA Food and Drug Administration FFDCA Federal Food, Dr ug, and Cosmetic Act FGD flue-gas desulfurization FIFRA Federal Insecticide, Fungicide, and Rodenticide Act FQPA Food Quality Protection Act FWP Final Work PlanPage 7 of 68 g gram g/mol grams per mole GLN guideline number HPV high production volume IDS Incident Data System KDDC potassium dimethyldithiocarbamate Koc organic carbon normalized soil-water partition coefficient Kd soil-water partition coefficient Kow octanol-water partition coefficient L liter LC 50 median (or 50 percent) lethal concentration
LD 50 median (or 50 percent) lethal dose LOAEC lowest-observed-adverse-effect-concentration LOC level of concern LOD limit of detection LOEC lowest-observed-effect-concentration LOAEL lowest-observed-adverse-effect-level Log K ow logarithm of the octanol-water partition coefficient ml/g milliliter per gram mg/kg milligram per kilogram mg/kg/day milligram per kilogram per day mg/L milligram per liter mm Hg millimeter of mercury MOE margin of exposure MRID Master Record Identification (number) MRL maximum residue limit MUP manufacturing use product NA not applicable
nm nanometers NOAEC no-observed-adverse-effect-concentration NOAEL no-observed-adverse-effect-level NPDES National Pollutant Discharge Elimination System Oc organic carbon OCSPP Office of Chemical Safety and Pollution Prevention OECD Organization for Economic Co-operation and Development OPP Office of Pesticide Programs PAD population adjusted dose PAI pure active ingredient PDM Probabilistic Dilution Model PC Code Pesticide Chemical Code PCF pounds per cubic foot pH power of hydrogen or power of the concentration of the hydrogen ion PHED Pesticide Handler’s Exposure Data PIS primary irritation score pKa power of the acid dissociation constant or negative base-10 logarithm of the acid dissociation constant of a solution ppb parts per billionPage 8 of 68 PPE Personal Protective Equipment ppm parts per million PWP Preliminary Work Plan QSAR quantitative structure-activity relationship RED Reregistration Eligibility Decision RfD reference dose RQ risk quotient SAR structure activity relationship SF safety factor SLN Special Local Need (Registra tions under Section 24(c) of FIFRA) SSTS Section Seven Tracking System SO2 sulfur dioxide TEP typical end-use product TGAI technical grade active ingredient TMDL total maximum daily loads TMTDS tetramethylthiuram disulfide (Thiram) TMTMS tetramethyl thiomonosulfide TMTU tetramethyl thiourea UF uncertainty factor UV/VIS ultraviolet/visible light absorption WP wettable powder WPS Worker Protection Standard WWTPs wastewater treatment plantsPage 9 of 68 

### EXECUTIVE SUMMARY

The Environmental Protection Agency (referred to as the “EPA”, “USEPA”, or “the Agency”) has evaluated the risks from the registered us es of 2-(decylthio) ethanamine hydrochloride (DTEA·HCl). Since DTEA-HCl is currently not marketed in the US, exposures predicted in this document are not occurring at this time and are theo retical only. However, the Agency assumes that DTEA-HCl could be used at some time in the future. Therefore, the risk assessment covers any potential future exposure if the product becomes active.

Since DTEA very rapidly dissociates from DT EA·HCl in aqueous so lution, this assessment focuses on DTEA. EPA has determined that ther e are unreasonable adverse effects to non-target aquatic and terrestrial organisms that may result from exposure to DTEA.

Based on the label requiring closed-loading, no qu antitative occupational human health risk assessment was conducted as this label requirem ent minimizes occupational exposure. For the human health risk assessment, no dietary risk assessment is necessary because dietary (food and drinking water) exposures are expected to be mini mal based on use patterns and water treatment.

A theoretical quantitative ecological risk assessment was conducted. Exposure levels were modeled in a variety of ways in cluding incorporation of wastewater treatment prior to discharge and no wastewater treatment, the risk results indicated exceedance of levels of concern for exposure of aquatic organisms for both federally listed endangered (liste d) species and non-listed species in the water column and exceedance of levels of concern for aquatic benthic invertebrates. Aquatic food chain transfer a nd bioaccumulation of DTEA was identified to potentially pose risks to mammals and birds.Page 10 of 68 

### 1.0 INTRODUCTION

This document is the United States Envir onmental Protection Agency’s (USEPA, EPA or “the Agency”) Preliminary Risk Assessment (P RA) for 2-(decylthio) ethanamine hydrochloride (DTEA·HCl). The PRA document explains what type of exposure analysis was conducted for humans and nontarget aquatic and terrestrial organisms, provides exposure estimates used to assess human health and ecological risks, characte rizes the uncertainties of the risk assessments conducted and draws conclusions.

The registration review process was designed to include a public pa rticipation component to solicit input from interested stakeholders. Th e Agency intends, by sharing this information in the docket, to inform the public of what it know s about the risks from th e registered DTEA·HCl uses and what types of new data or other inform ation would be helpful for the Agency to receive as it moves toward a decision on DTEA·HCl. The Ag ency encourages all interested stakeholders to review the PRA and to provide comments a nd additional information that will help the Agency’s decision-making process for this chemical.



### 1.1 Case Overview

The docket for the DTEA·HCl Ca se (5029) was established at http://www.regulations.gov in docket number EPA-HQ-OPP-2009-0366.

DTEA·HCl is a liquid, organic industrial biocide commonly known by the trade name DTEA. The manufacturing-use prod uct, Antimicrobial DTEA Tec hnical (99.8%), is registered for formulation of pesticide products for use in re-circulating cooling water systems. These systems include evaporative condensers, heat ex change water systems, commercial and industrial cooling towers, influent systems such as flow-through filters and lagoons, industrial water scrubbing systems and brewery pasteurizers. Th e end-use product contains 15% DETA and is registered to control bacteria l, fungal, and algal slimes.

DTEA·HCl was first registered in the United States in 1993 for use in recirculating water process systems. Since DTEA-HCl is currently not marketed in the US, exposures predicted in this document are not occurring at this time and are theoretical. However, the Agency assumes that DTEA-HCl could be used at some time in the future. Therefore, the risk assessment covers any potential future exposure if the product becomes active. A Reregistration Eligibility Decision (RED) was not issued by the Agen cy for DTEA·HCl. A summary of product chemistry, environmental fate and ecotoxicity da ta for DTEA·HCl regist ration review decision document was issued in December 2009.



### 1.2 Recent Regulatory Actions The docket for DTEA·HCl was opened June 24, 2009 and the final work plan (EPA-HQOPP-2009-0366-0007) was posted December 16, 2009 af ter public comments were addressed.Page 11 of 68 No actions have occurred with this chemical si nce the posting of the fina l work plan in 2009. A registration review generic DCI wa s issued in August 2011. All data which were required in that DCI have been submitted, reviewed and were found acceptable. Those data were used to inform this risk assessment.



### 1.3 Work Plan Modifications
A generic data call-in (GDCI) was sent to registrants with products August 17, 2011 (EPA-HQ-OPP-2009-0366-0007-0010). Two fate studies (835.1110 Activat ed Sludge Sorption Isotherm and 835.3110 Ready Biodegradability) and an ecological effects st udy (Algal toxicity Tier II definitive study with the freshwater green alga, Selenastrum capricornutum ) were required. All of these studies were submitted and reviewed.

Since the final work plan (FWP) was posted, the Agency practice for evaluating ecological risks from recirculating cooling pr ocess water systems has expanded to include evaluation of sediment exposure pathways a nd bioaccumulation up the aquatic food chain to terrestrial wildlife. Therefore, not all the data needed to address these exposure pathways was requested in the FWP. The Agency has used alte rnative methods to address these data gaps, and these are addressed in appropriate sections.



### 2.0 ENVIRONMENTAL FATE ASSESSMENT

In aqueous solution DTEA is persistent unde r abiotic conditions at pH 5, 7, and 9. Its solubility is low in water. The Henry’s law c onstant value indicates th at DTEA has a moderate tendency to volatilize from water surf aces to air. Its half life in ai r is about 3 hours, and it is not likely to persist in air. It is immobile on soil surfaces, and sludge surfaces. It is not ready biodegradable. Its Log Kow is high which indicates that it is likely to be bioaccumulative. The dissipation pathway appears to be binding to so il/sediments and therefore, the possibility of adverse effects on benthic organisms exists.



### 3.0 HUMAN HEALTH RISK ASSESSMENT

3.1 Human Health Hazard
For DTEA, the registrant submitted the acute toxicity studies, a 90-day dermal toxicity test, a developmental test and the mutagenicity studies.

3.1.1 Subchronic Toxicity An acceptable 90-day dermal study (MRID 40634003) was conducted with Fisher 344 rats. The rats were treated for 13 weeks with pure solid DTEA·HCl and the dose levels were 0, 1, 5 and 25 mg/kg/day. The dose was administered on weekdays for a total of 65 applications. The test material was spread over the skin of ra ts with a syringe. The tested area was occluded for 6 hours with a gauze patch under an elastic bandage. The mean weight of the male andPage 12 of 68 female rat was 262.5 gm and 171.6 gm, respectively. Approximately 20 rats were tested for each dose level. The systemic NOAEL was 25 mg/kg/day (h ighest dose tested) and the NOAEL for skin irritation was <1 mg/kg/day base d on skin thickenin g, focal erythema, and multifocal crust formation at a LOA EL of 1 mg/kg/day was established. Dermal irritation was seen between 8 to 12 weeks after dosing.

3.1.2 Developmental Toxicity A developmental toxicity study (MRID 40634002) was conducted using female Fisher 344 rats with dose levels 0, 2.5, 15, 25 mg/kg/day of DTEA·HCl given by gavage on gestation days 6-15. This study was upgraded to acceptable in 1992 (TXR009621). The maternal NOAEL was 2.5 mg/kg/day. The maternal LOAEL of 15 mg/kg/day was based on decreased body weight and body weight gain as well as suggestive decrease in food and water consumption. There did not appear to be any feto toxicity or teratoge nic effect at any dose levels. Therefore the NOAEL for developmen tal toxicity is 25 mg/kg/day or the highest dose tested.

3.1.3 Mutagenicity In a test of unscheduled DNA synthesis in primary rat hepatocytes, DTEA did not demonstrate mutagenic potential (MRID 40126410). No evidence of mutagenicity or genetic toxicity was found in an in vivo mouse bone marrow micronucleus assay (MRID 40126410). DTEA did not exhibit mutageni c potential in a Chinese hamste r ovary cell forward mutation study (MRID 40126409).

3.1.4 Literature Search Results: Searches of the following databases us ing the key words 2-(Decylthio)Ethanamine Hydrochloride and 2-(Decylthio)Ethanamine on 07/21/2013 resulted in no DTEA-HCl studies being located that is useful fo r human health risk assessment:

 Hazardous Substances Data Bank (HSDB);

 Toxicology Literature Online (TOXLINE);

 ChemIDPlus Advance; and

 Toxicology Data Network (ToxNET).

As the DTEA-HCl label requires that the product be added via closed mixing/loading systems, no additional toxicology studies are required for occupati onal risk assessment. Similarly, additional toxicology studies are not re quired to conduct dietary risk assessments as dietary exposure is not expect ed to occur at this time.



### 3.2 Dietary Assessment DTEA-HCl is registered for use in reci rculating cooling water systems (evaporative condensers, heat exchangers, c ooling towers, influent systems such as flow-through filters andPage 13 of 68 lagoons, industrial water scrubbing systems, and br ewery pasteurizers). In the Preliminary and Final Workplans of the DTEA Registration Review , waste water from thes e uses of DTEA-HCl was considered to be rarely discharged. However, the Agency has recently revisited the extent of wastewater discharges associated with various types of commerci al and industrial water systems. It has been determined that recirculating coo ling water systems do, indee d, discharge significant volumes of waste water into natu ral water bodies. Regarding propert ies that are lik ely to affect its behavior, aqueous solutions dissociate into D TEA and HCl. Once DTEA is released into the environment, DTEA has a low water solubil ity (0.0035 g/100 g water), fairly high log Kow (3.27), fairly high vapor pressure (1.8 x 10 -4 mmHg), moderate Henry’s Law Constant (2.79 x 10 -5 atm-m 3 /mole), resistance to hydrolysis, high te ndency to adsorb to organic matter and sludge, instability in air, and low bioavailability (see fate section of this memorandum). The use sites, frequency of discharge, and physical, ch emical, and environmenta l fate properties of DTEA-HCl have made it necessary for the agency to consider the need to conduct human dietary (food and drinking water) risk assessments.

3.2.1 Dietary (Food) Exposure A dietary (food) risk assessment was not pe rformed for DTEA-HCl in the past because there were not considered to be any direct or indirect food uses of DTEA-HCl. No tolerance or exemption from tolerance has been established by EPA. As noted above, waste water discharges of the dissociated DTEA from recirculating c ooling water systems are expected. DTEA has a number of properties indicating th at it has the potential to biocon centrate in fish and shellfish. However, DTEA-HCl is not currently being mark eted; therefore, dietar y exposure via fish and shellfish is not occurring. In the event DTEA-HCl is marketed, the Agency has determined that dietary exposure due to consumption of DTEA-c ontaminated fish will be minimal despite the uncertainties noted above. Humans rarely rely on fish and shellfis h from an isolated area in the vicinity of a recirculating water system as a major source of animal protein. Additionally, any discharged DTEA is expected to become diluted in the receivi ng water body. Therefore, a dietary assessment is not required at this time.

3.2.2 Drinking Water Exposure A dietary (drinking water) risk assessment was not performed for DTEA-HCl in the past because recirculating cooling wate r systems were considered to be rarely discharged. However, as noted above, waste water discharges of th e dissociated DTEA from recirculating cooling water systems are expected.

Surface water concentrations estimated using General Population Exposures and Industrial Releases module of E-FAST assume that wate r releases can occur up to 360 days per year without wastewater treatment and that all DTEA re leased to surface water c ould be present in the dissolved phase in the water column. These estimates are very conservative and do not account for DTEA’s propensity to partition from water in to sediment, the effect of wastewater or drinking water treatment. The best management practice for operation of recirculating coolingPage 14 of 68 water systems is to perform waste water treatmen t prior to discharge a nd, as indicated by the Activated Sludge Sorption Isothe rm study, 93-98% of the DTEA is removed via waste water treatment prior to being discharged to surface water (MRID 49004201). Additionally, any discharged DTEA will rapidly be adsorbed to partic ulates that will eventually become part of the sediment. Finally, methods of drinking water tr eatment such as flocculation and sedimentation will further lower DTEA residues from potential drinking water. For these reasons, EPA has determined that no further human health drinki ng water assessment is necessary for DTEA.



### 3.3 Residential Assessment Because the existing DTEA-HCl label uses will not result in residential exposures, residential handler and postapplication assessments will not be required.



### 3.4 Aggregate and Cumulative Exposure

3.4.1 Aggregate Exposures As no dietary (food or drinking water) or re sidential exposures are associated with the registered uses of DTEA-HCl, there ar e no human health risks to aggregate.

3.4.2 Cumulative Exposures With respect to cumulative exposure, unlike other pesticides for which EPA has followed a cumulative risk approach based on a common mechanism of toxicity, EPA has not made a common mechanism of toxicity finding as to D TEA-HCl and any other substances and DTEAHCl does not appear to produce a toxic meta bolite produced by other substances. For the purposes of this preliminary risk assessment, therefore, EPA has not assumed that DTEA-HCl has a common mechanism of toxicity with othe r substances. For information regarding EPA’s efforts to determine which chemicals have a comm on mechanism of toxicity and to evaluate the cumulative effects of such chemicals, see http://www.epa.gov/pesticides/cumulative/

.



### 3.5 Occupational Assessment An occupational and/or residential exposur e assessment is required for an active ingredient if (1) cert ain toxicological criteria are triggered and (2) there is potential exposure to handlers (mixers, loaders, applicators, etc.) duri ng use or to persons en tering treated sites after application is complete.

The Agency received product use inform ation (MRID 49004204) for the ready-to-use product Antimicrobial DTEA 15% (EPA Re g # 464-619) which was submitted by the Dow Chemical Company in response to the DTEA·HCl Generic Data Call-In. EPA has reviewed the study (D407660) and determined that it is accep table according to the requirements of OPPTS/OCSPP guideline 875.1700 [Applicator Exposure Product Use Information].Page 15 of 68 The Agency believes that closed mixing/loading systems can be an effective risk mitigation measure when required on pesticide labels to reduce risks identified for open mixing/loading procedures. The end use product (EPA Reg# 464-619) restricts the loading to closed systems. Therefore, the handler exposure is minimal and not quantified.

A post application assessment is not require d based on the dilution of the product in the water systems, and therefore would redu ce the vapor pressure to below 1 x 10 -4 (the cutoff for assessing inhalation exposure to vapors of DTEA).



### 3.6 Endocrine Disruptor Screening Program (EDSP)
As required by FIFRA and FFDCA, EPA revi ews numerous studies to assess potential adverse outcomes from exposure to chemical s. Collectively, these studies include acute, subchronic and chronic toxici ty, including assessments of carcinogenicity, neurotoxicity, developmental, reproductive, and general or syst emic toxicity. These studies include endpoints which may be susceptible to endocrine influenc e, including effects on endocrine target organ histopathology, organ weights, es trus cyclicity, sexual maturation, fertility, pregnancy rates, reproductive loss, and sex ratios in offspring. Fo r ecological hazard assess ments, EPA evaluates acute tests and chronic studies that assess growth, developmen tal and reproductive effects in different taxonomic groups. As part of the re registration decisions for DTEA-HCL beginning in 1993, EPA reviewed these data yet never selected th e most sensitive endpoints for relevant risk assessment scenarios from the existing hazard data base presumably because the hazard database was very limited and only occupational expos ure was expected. However, as required by FFDCA section 408(p), DTEA-HCL is subject to the endocrine scre ening part of the Endocrine Disruptor Screening Program (EDSP).

EPA has developed the EDSP to determin e whether certain substances (including pesticide active and other ingredie nts) may have an effect in hu mans or wildlife similar to an effect produced by a “naturally occurring estr ogen, or other such endocrine effects as the Administrator may designate.” The EDSP empl oys a two-tiered approach to making the statutorily required determinations. Tier 1 consists of a battery of 11 screening assays to identify the potential of a chemical substance to interact w ith the estrogen, androgen, or thyroid (E, A, or T) hormonal systems. Chemicals that go through Tier 1 screening and are found to have the potential to interact with E, A, or T hormonal sy stems will proceed to the next stage of the EDSP where EPA will determine which, if any, of the Ti er 2 tests are necessary based on the available data. Tier 2 testing is designe d to identify any adverse endocr ine-related effects caused by the substance, and establish a dose-re sponse relationship between the dos e and the E, A, or T effect.

Under FFDCA section 408(p), the Agency must screen all pesticide chemicals. Between October 2009 and February 2010, EPA issued test orders/data call-ins for the first group of 67 chemicals, which contains 58 pest icide active ingredients and 9 in ert ingredients. DTEA-HCL is not among the group of 58 pesticide active ingredient s on the initial list to be screened under thePage 16 of 68 EDSP. Accordingly, as part of registration revi ew, EPA will issue future EDSP orders/data callins, requiring the submi ssion of EDSP screening assays for DTEA-HCL.

For further information on the status of the EDSP, the policies and pr ocedures, the list of 67 chemicals, future lists, the test guidelines and the Tier 1 screening battery, please visit our website: http://www.epa.gov/endo/

.



### 4.0 ECOLOGICAL RISK ASSESSMENT

4.1 Selected Ecological Toxicity Endpoints
All registered uses of the DTEA manufact uring-use product are for the formulation of pesticide products for use in re-circulating coo ling water systems. The DTEA Technical is diluted to concentration of 15% a nd this formulation is used to treat the water systems. In the past the cooling tower use was considered an “indoor use” and exposure to non-target organisms was not expected. Under the newly revised 158 W guidelines, this use is now subject to an evaluation to determine if exposure to non-target organisms is occurring and if so, should be subject to risk mitigation measures. Ecological effects endpoints selected for assessing risks from use in recirculating cooling systems are presented in Table 1.

Table 1 Ecological Effects Endpoints Sele cted for Assessing Risks from Use in Recirculating Cooling Systems

Receptor Group Surrogate Species Risk Scenario Toxicity Endpoint Reference

Freshwater fish Fathead minnow Acute 96-h LC 50 = 220 ppb 40126416, 42482901

Chronic NOAEC = 36.5 ppb 41198302, 41198304, 41512601, 41779902

Freshwater invertebrates Acute 48-h EC 50 = 34 ppb 41198303, 41198305, 41512602, 41779901

Chronic NOAEC > 7.8 ppb 41198303, 41198305, 41512602, 41779901Page 17 of 68 Receptor Group Surrogate Species Risk Scenario Toxicity Endpoint Reference

Freshwater benthic invertebrates Subchronic/ Chronic At Koc of 9810 L/kgNOAEC (1% oc) = 0.77 mg/kgsedimentNOAEC (4% oc) = 3.1 mg/kgsedimentNOAEC (5% oc) = 3.8 mg/kgsediment

At Koc of 21,566 L/kgNOAEC (1% oc) = 1.68 mg/kgsedimentNOAEC (4% oc) = 6.7 mg/kgsedimentNOAEC (5% oc) = 8.4 mg/kgsediment Modeled using EqP method see Appendix E, see Table 8

Estuarine/marine fish Acute Not required A

-- Chronic Not required A

--

Estuarine/marine invertebrates Mollusk Acute Not required A

--
Shrimp Acute Not required A

-- Chronic Not required A

-- Estuarine/marine benthic invertebrates Subchronic/ Chronic Not required A

--
Algae Nonlisted IC 50 >11.7 ppm 49004203 Listed NOAEC > 11.7 ppm Aquatic vascular plants Duckweed Nonlisted IC 50 = No data Listed NOAEC = No data
Seedling Emergence Nonlisted IC 25 = No data Listed NOAEC = No data
Vegetative vigor Nonlisted Not required B

-- Listed Not required B

--

Birds Mallard duck Acute LD 50 > 2250 mg/kg-bw 40126412 Mallard duck Subacute dietary LC 50 > 5620 ppm (30% mortality at highest dose) 40126414, 40126413 Chronic NOAEC = No data

Mammals Acute LD 50 = 2272mg DTEA/kg-bw 40126405 Chronic NOAEL = No data Nontarget terrestrial insects Honey bee Acute Not required C

--

A The label specifically prohibits the direct flushi ng of the coolant to estuarine/marine waters.

B For cooling tower use pattern, spray drift and irrigation is not considered to be a pathway of concern.

C For cooling tower use pattern, exposure of terrestrial beneficial insects is not considered to be a pathway of

concern.



### 4.2 Summary of Exposures

4.2.1 Exposure of Aquatic Organisms to DTEA Downstream of Recirculating Cooling Towers The general population and ecological exposures for industrial releases module (hereinafter referred to as the Industrial Releas es Module) of the Exposure and Fate AssessmentPage 18 of 68 Screening Tool (E-FAST) was used to estimate exposure of aquatic organisms to DTEA, the dissociation product of the active ingredient D TEA HCl, downstream of recirculating cooling towers. According to the product label (EPA Reg. No. 464-619), DTEA·HCl is present in the product, Antimicrobial DTEA·HCl 15%, as 15% of the formulation. The corresponding acid equivalent of DTEA is 12.8% of this formulation.

According to the product label, there are two methods of treatment for control of bacteria, fungi, and algae in recirculati ng cooling water systems: (1) intermittent or slug method and (2) continuous feed method. For both methods of treatm ent, the label specifies application rates of Antimicrobial DTEA 15% for both initial trea tment of fouled systems and maintenance treatment. Maintenance treatments can ra nge from 0.5 to 25 fluid ounces of product per 1000 gallons of water for the intermittent or slug met hod of application and 0.5 to 2 fluid ounces of product per 1000 gallons of water fo r the continuous feed method. Initial treatmen t of fouled systems can range from 6 to 41 fluid ounces of product for both intermittent/slug and continuous feed methods. Application rate s recommended on the product labe l are tabulated in Table 2.

Table 2 Application Rates from the Product Label

INTERMITTENT OR SLUG METHOD Initial treatment of fouled systems 6-41 fluid ounces per 1000 gallons of water in the system Maintenance treatment 0.5-25 fluid ounces per 1000 gallons of water in the system CONTINUOUS FEED METHOD Initial treatment of fouled systems 6-41 fluid ounces per 1000 gallons of water in the system Maintenance treatment 0.5-2 fluid ounces per 1000 gallons of water in the system

Potential exposures to aquatic organisms we re estimated for applications of 41, 25, 6, 2, and 0.5 fluid ounces of product appl ied per 1000 gallons of water. Adjusting for product density of 8.5 lbs per gallon, the correspond ing amounts of product applied w ould be slightly higher.

Table 3 presents the applicat ion rates of Antimicrobial D TEA 15% adjusted for density and the corresponding concentrations in parts pe r million (ppm) expressed as DTEA equivalents (12.8%). The table also presents corresponding environmental releases of DTEA to surface water from large-size (recirculation rate of 100,000 gallons per minute) and moderate-size (recirculation rate of 2000 gallons per minute) recirculating cooling towers.

Table 3 Application Rates from Label Ad justed for Density and DTEA Equivalents

Product Application rate Application rate adjusted for product density of 8.5 pounds per gallon DTEA Concentration (ppm acid equivalents) Environmental Release: Large-Size Cooling Tower

(kg/site/day) Environmental Release: Moderate-Size Cooling Tower

(kg/site/day) 41 fluid ounces 41.8 fluid ounces 40 140 2.8 25 fluid ounces 25.4 fluid ounces 24.4 84 1.7 6 fluid ounces 6.1 fluid ounces 5.9 20.4 0.41 2 fluid ounces 2.0 fluid ounces 1.95 6.7 0.13 0.5 fluid ounces 0.5 fluid ounces 0.5 1.7 0.03Page 19 of 68 Potential exposures and risks to DTEA from releases of blowdown water from recirculating cooling towers to surface water were examined for the following circumstances:

 maintenance treatments versus initial treatments for fouled systems;

 large-size versus moderate-size recirculating cooling towers;

 high-end versus average case scenarios from E-FAST; and

 wastewater treatment versus no wastewat er treatment prior to discharge of blowdown water to surface water

In the case where no treatment of blowdown water is assumed, the industrial releases module of E-FAST is run assuming no removal. In the case where it is assumed that blowdown water undergoes wastewater treatment prior to di scharge, the industrial releases module of EFAST is run assuming 93 percent removal based on activated sludge sorpti on isotherm data that indicate that from 93 to 98 pe rcent of DTEA is removed dur ing wastewater treatment via sorption to activated sludge. Surface water concentrations are estimated based on the distribution of plant flows and stream flows from the Steam El ectric Power Plants SIC code. Model results are expressed as days per year of exceedance of concentr ations of concern for aquatic organisms downstream of recirculating cooling towers.

4.2.1.1 Sediment EECs The general population and eco logical exposures for industrial releases module of EFAST used to estimate exposure in surface wate rs downstream of recirculating cooling water systems does not provide estimates of sediment c oncentrations. Local sediment concentrations were modeled using an equilibrium partitioning (E qP) to sediment approach, estimated surface water concentrations from E-FAST output for th e maintenance scenarios, and Koc values for sediment and activated sludge. A description of the method is provided in Appendix E. Estimated exposure concentrations in local sedi ments for high-end conditions, under wastewater treatment and no wastewater treatment c onditions using the natural sediment K oc and activated sludge K oc values (which assumes local sediment is predominated by WWTP oc output) are provided in Table 4. An additi onal analysis based on the 10% 30Q 5, which is more reflective of everyday inputs using the activated sludge Koc was included in the table, as was an analysis of the potential for sorbed oc from a WWTP whic h was exposed to highe r concentrations in influent to contribute to sediment exposure.Page 20 of 68 Table 4 Estimated Local Sediment Concentrations for With and Without Wastewater Treatment of Blowdown Water Prior to Discharge

Scenario C w (mg/L solution) Koc (mg/kg-oc per mg/L solution) C s (mg/kg-sediment) for f oc (kg-oc/kgsediment) 0.002 0.01 0.02 0.04 0.05 84 kg/site/day, Large-Size Facility, High-End Scenario w/WWTP, 10% 7Q10 0.569 9,810 11.2 55.8 112 223 279 w/WWTP, 10% 7Q10 0.569 21,566 24.5 123 245 490 613 w/o WWTP, 10% 7Q10 8.1 9,810 160 798 1,595 3,191 3,989
WWTP effluent oc 8.1* 21,566 351 1,754 3,507 7,015 8,769 w/ WWTP, 10% 30Q5 0.335 21,566 14.4 72.2 144 289 361 0.03 kg/site/day, Medium-Size Facility, Average Scenario w/WWTP, 10% 7Q10 0.0002 9,810 0.004 0.020 0.039 0.078 0.098 w/WWTP, 10% 7Q10 0.0002 21,566 0.009 0.043 0.086 0.172 0.216 C s = DTEA sediment concentration; C w = DTEA dissolved surface water concentration; w/ = with; w/o = without * An estimate of DTEA sorbed to effluent oc which may potentially contribute to sediment where influent DTEA concentration (8.1 mg/L) is set to the di scharge level without wastewater treatment.

4.2.2 Analysis of Influence of Ratios of Plant Flow to Stream Flow Distributions on Estimates of Numbers of Days per Year of Exceedance of COCs The General Population Exposures and Indus trial Releases module of E-FAST was run using the distribution of plant fl ows to stream flows for the Industrialized POTWs SIC code. A sample comparison of estimates of number of days of exceedance of COCs out of 360 days per year of release of DTEA for the Steam Electri c Power Plants SIC code and the Industrialized POTWs SIC code is presented in Table 5 assuming that 2.8 kg/site-day of DTEA is released to water and 93 percent is removed via sorption to activated sludge duri ng wastewater treatment.
Table 5 Comparison of Number of Days p er Year of Exceedance of COCs: Steam Electric Power Plants SIC Code versus Industrialize d POTWs SIC Code (2.8 kg/site/day and 93% Removal During WWT and 360 D ays of Release per Year)

SCENARIO COC = 110 ppb COC = 17 ppb COC = 10 ppb COC =1.7 ppb HIGH-END SCENARIO Steam Electric Power Plants SIC Code 18 91 126 270 Industrialized POTWs SIC Code 4 88 144 314 AVERAGE CASE SCENARIO Steam Electric Power Plants SIC Code 2 9 13 37 Industrialized POTWs SIC Code 0 12 23 91

4.2.3 Estuarine/Marine Organisms No exposure modeling was conducted specifica lly for estuarine/marine environments. There are no estuarine/marine t oxicity data. See Section 4.4.2 fo r discussion of potential risks.Page 21 of 68 4.2.4 Residue Levels in Aquatic Biota There were no fish or shell fish bioconcentration studies submitted to the Agency or found in the open literature fo r DTEA. EPI Suite (version 4.1 1), which includes the BCFBAF Program (version 3.01), was used to estimate bi oconcentration and bioaccumulation factors (BCF and BAF, respectively) for DTEA. Results are provided in Appendix F. Bioaccumulation factors (BAFs) range from 210.3 L/kg ww (log BA F 2.329) in the lower trophic level to 239.3 L/kg ww (log BAF 2.379) for the upper trophic level assuming biotransformation occurs. Assuming no biotransformation, the upper troph ic level BAF is 927 L/kg ww (log BAF 2.967). The BAFs and estimated exposure co ncentrations in water were used as described in Appendix F to estimate residues in aquatic organisms.

Residue levels for the maintenance use appl ications were estimated under conditions of no wastewater treatment prior to discharge and wa stewater treatment prior to discharge. The fouled system treatment was assumed to occur in frequently and therefore unlikely to result in residue levels in the aquatic system of concer n. At the assumed one time annual use rate for a fouled system, daily maintenance would be e xpected to control exposure concentrations. Mitigating factors such as propor tion of population exposed on the day of release, proportion of diet these organisms would const itute, growth dilution, sediment burial, etc. all make it unlikely to result in any detectable residues of concern.

4.2.4.1 Cooling Tower Maintenance Use with Wastewater Treatment Prior to Discharge At the high end (10% 7Q10) estimated dissolved water conc entration of 0.569 mg DTEA/L, under maintenance use of DTEA·HCl , and using the upper trophic level log BAF estimate of 2.967 (assumption of no biotransformation) results in an estimated residue level of 527 mg DTEA/kg-tissue ww. A ssuming biotransformation the upper trophic level log BAF estimate of 2.379 results in an estimated residue level of 136 mg/kg-tissue ww. At the lowest label application rate for maintenance the tissu e residue levels for th is case (0.185 mg/kg-tissue ww and 0.048 mg/kg-tissue ww without and w ith biotransformation, see Appendix F).

4.2.4.2 Cooling Tower Maintenance Use with No Wastewater Treatment Prior to Discharge Setting the water concentr ation to the high end (10 th percentile 7Q10) estimated dissolved water concentration of 8.132 mg DTEA/L and usi ng the upper trophic level log BAF estimate of 2.967 (assumption of no biotransformation) results in an estimated residue level of 7,537 mg DTEA/kg-tissue ww. Assuming biotransformat ion occurs, the upper trophic level log BAF estimate of 2.379 results in an estimated residue level of 1,946 mg/kg-tissue ww.



### 4.3 Risk Estimation
Risk estimation integrates the results of the exposure and ecotoxicity data to evaluate the likelihood of adverse ecological eff ects. There are generally two approaches used in assessing risks from industrial process and water systems, a risk quotient (RQ) me thod and a probabilisticPage 22 of 68 method. In this assessment RQ values were not calculated because of limitations in exposure modeling and/or toxicity data. However, in formation was used semi-quantitatively and references to these values are made within th e document and therefore this information is provided to aid understanding of the comparisons and conclusions drawn. Details of these methods are described in Appendix C.



### 4.4 Risks to Freshwater Fish and Aquatic Invertebrates.

4.4.1.1 Risks to Freshwater Organisms based on Maintenance Treatment Scenarios

Water Column

The amount of product containing DTEA used for maintenance treatment can range from 0.5 to 2.0 fluid ounces for continuous feed me thods and 0.5 to 25 fluid ounces based on intermittent or slug methods. For the purpose of assessing exposures to aquatic organisms from maintenance applications, it is assumed that e nvironmental releases vi a cooling tower blowdown water to surface water can occur 360 days per year . Results from the industrial releases module of E-FAST based on maintenance applications are pres ented in Appendix D in Tables 10 through 17. Tables 10 through 13 present results based on th e assumption that there is direct discharge to surface water (no removal of DTEA via wastewater treatment pr ior to discharge of blowdown water to surface water). Tables 14 through 17 present results based on the assumption that blowdown water undergoes wastewater treatment prior to discharge a nd that 93 percent is removed based on activated sludge sorption isothe rm data that indicate that from 93 to 98 percent of DTEA is removed dur ing wastewater treatment via sorption to activated sludge.

In summary, the estimated numbers of days of exceedance of concen trations of concern for aquatic organisms increase as environmental re leases increase for maintenance treatment and

are:

 higher for large-size cooling towers th an for moderate-size cooling towers;

 higher for recirculating cooling towers that di scharge blowdown water without treatment than those that discharge blowdown water following wastewater treatment; and

 higher for the high-end scenario than the average case scenario.
It is important to note that there are exceedan ces of concentrations of concern for aquatic organisms for all scenarios examin ed, including the scenario that predicts the lowest number of days of exceedance of concentrations of concer n: the average case scenar io for a moderate-size cooling tower that discharges blowdown water following wastewater treatment (See Table 17). At the lowest environmental release for modera te-size cooling towers of 0.03 kg/site/day (0.5 ppm), however, the only COC exceeded is that for endangered freshwater invertebrates (1.7 ppb), and that exceedance is only for one day of 360 days per year of release.Page 23 of 68 Benthic Invertebrates

Under the high end use scenario for both th e 7Q10 and 30Q5 flow conditions and with wastewater treatment prior to discharge, estima ted DTEA concentrations in sediments (11.2 to 613 mg/kg-sediment, Table 4) under a range of orga nic carbon levels exc eed the chronic DTEA NOAEC values for benthic organism s (0.15 to 8.4 mg/kg-sediment, Ta ble 1). This indicates the potential for chronic effects to the aquatic benthic organisms under the maximum label use rate. For the no wastewater treatment scenario prior to discharge, the risks are indicated to be greater (estimated sediment concentrations range fr om 160 to 3,989 mg/kg-sediment compared to NOAEC values of 0.15 to 8.4 mg/kg-sediment).

At the lowest maintenance application rate, for medium-size facilities, and average conditions, estimated DTEA sediment concen trations (0.004 to 0.216 mg/kg-sediment) do not exceed the chronic DTEA NOAEC values for be nthic organisms (0.15 to 8.4 mg/kg-sediment, respectively, Table 1). This indicates under these conditions, unacceptabl e adverse effects to benthic invertebrates due to DTEA are not likely.

4.4.1.2 Estimates of Exposures and Risks Based on Initial Treatment of a Fouled System Scenarios

Water Column Exposure

According to the product label, the amount of product containing DTEA used for initial treatment can range from 6 to 41 ounces for both continuous feed and intermittent/slug methods. In the case of the continuous feed method, the recommended application ra te range of 6-41 fluid ounces for initial treatment is always higher than the recommended applic ation rate range of 0.50 to 2.0 fluid ounces for maintenance treatment. In the case of the intermittent or slug method, the recommended application rate range of 6-41 ounces for initial treatment is not always higher than the recommended applicati on rate range of 0.5-25 fluid ounces for maintenance treatment. The annual frequency and duration of initial treatm ent applications is uncertain. For the purpose of assessing exposures to aquatic organisms from initial treatment applications, it is assumed that environmental releases of DTEA to surface wate r via cooling tower blowdown water occur for one day. Tables 18 through 25 present information on whether or not concentrations of concern for aquatic organisms are exceeded for one day of release to surface water.

Surface water concentrations estimated using General Population Exposures and Industrial Releases module of E-FAST assume that all DTEA released to surface water is present in the dissolved phase in the wa ter column. Based on the log K ow value of 3.7 for DTEA, as a result of the potential for DTEA to sorb to suspended solids and aquatic sediments, concentrations in the dissolved phase of the wa ter column would be expected to be somewhat lower than modeling results indicate; consequentl y, the number of days per year of exceedance of concentrations of concern woul d also be expected to be somewhat lower than values based on model estimates.Page 24 of 68 4.4.2 Risks to Estuarine/Marine Organisms For use in facilities discharging to estuar ine/marine environments the DTEA-HCl label requires treatment through a WWTP which would reduce the amount of DTEA released to the environment by over 90%. However, based on the re sults for freshwater systems after treatment, potential risks for freshwater aqua tic organisms were identified. EP A does not have toxicity data for estuarine/marine organisms to show that they would be less sensitive to exposure to DTEA than freshwater organisms. In the absence of data. EPA assumes that the use and release of DTEA to estuarine and marine systems would resu lt in risks of concern fo r estuarine and marine aquatic organisms.

4.4.3 Risks to Piscivorous Birds and Mammals

4.4.3.1 Cooling Tower Maintenance Use with Wastewater Treatment Prior to Discharge No definitive acute risk quotients (RQs) can be calculated for birds because the acute oral
LD 50 (>2250 mg/kg-bw) and subacute dietary LC 50 (>5620 mg/kg-diet; 30% mortality at this dietary level) were greater th an the highest dose and concen tration tested, respectively. However, what is evident is that on a dietar y basis the potential D TEA residues in the upper trophic level, even under the high-end scenario and for an assumption of no biotransformation, are more than 10 times lower than the residue leve ls tested. Residue levels at the middle and lower trophic levels are expected to be even lower than the upper trophic level. Therefore, the potential for listed and nonlisted acute levels of concern (LOCs) for birds to be exceeded are considered unlikely. There are no chronic toxici ty data for avian species, therefore no chronic RQ could be calculated.

4.4.3.2 Cooling Tower Maintenance Use with No Wastewater Treatment Prior to Discharge Estimated upper trophic residue levels assuming no biotransformation (7,537 mg/kgtissue ww exceeds the subacute dietary level test ed with mallard ducks (5620 mg/kg-diet). Because this exposure level in the subacute dietary test resulted in 30% mo rtality, acute levels of concern would be expected to be exceeded for listed and nonlisted avian species. Under the high end exposure conditions estimated surface water c oncentrations exceed acute and chronic levels, therefore, while residue levels can be calculated based on this es timate the food chain is likely to disrupted and impacted by acute effects. Estim ated residues in the uppe r trophic level are not likely reasonable in this case.



### 4.5 Risk Characterization
DTEA-HCl is registered for use in re-c irculating process wate r systems to control bacterial, fungal and algal slimes. DTEA-HCl is not marketed at this time, so predicted exposures are theoretical. Since this use could have a potential for environmental exposure to non-target organisms, a risk assessment was conduc ted. This is particularly important since the studies included in this assessment indicate that DTEA is highly to very highly toxic to aquatic organisms on both an acute and chronic basis.Page 25 of 68 The results of the risk assessment indicate th at DTEA could potential ly adversely affect non-target aquatic organisms, and wildlife that in gest fish and shellfish. The risk assessment evaluated exposure and risks to aquatic organisms in the water column, in the benthic compartment, and to wildlife from bioaccumulation in the aquatic food chain. This section characterizes these potentia l risks and uncertainties.

Potential exposures and risks to DTEA from releases of blowdown water from recirculating cooling towers in the dissolved pha se of the water column were estimated for the following circumstances:

 Initial treatments for fouled systems (1 day event) versus maintenance treatments (360 days per year);

 Large

‐ size (1.7

– 84 kg/site/day DTEA to surface water ) versus moderate

‐ size (0.03

– 1.7 kg/site/day DTEA to surface water) recirculating cooling towers;

 High

‐ end versus average case scenarios from E

‐ FAST; and

 Wastewater treatment (93 percent removal of DTEA via sorption to activated sludge) versus no
wastewater treatment prior to discharge of blowdown water to surface water.

The influence of these factors on estimates of potential exposures and risks to DTEA is discussed in 4.4.1.1. A probabilistic approach that estimates the number of days of exceedance of concentrations of concern (C OCs) for aquatic organisms was used to estimate exposures and risks to key receptor groups.

Based on probabilistic modeling results, if the acute COC (one-half of theLC 50 or EC 50 ) determined for any key aquatic receptor group is exceeded for one day or more based on results from the high-end scenario (i.e., the 10 th percentile of the ratio of stream flows to plant flows), then potential acute risks to such receptor gr oups are indicated. In a ddition, if the endangered COC (one-twentieth of the LC 50 or EC 50 ) determined for any key aquatic receptor group is exceeded for one day or more based on results fro m the high-end scenario, then potential acute risks to endangered aquatic organisms in such rece ptor groups are indicated. Furthermore, if the chronic COC (NOAEC or NOAEL) for any key aquatic recepto r group is exceeded for 20 days or more based on results from the high-end scen ario, then potential chronic risks for such receptor groups are indicated.

For maintenance applications at large-size cooling towers, assuming 360 days per year of release of blowdown water to su rface water, the potential for acute risks to endangered and nonendangered freshwater fish and invertebrates and chronic risks to freshwater fish and invertebrates based on the high-end scenario is pr edicted at all application rates proposed on the product label whether or not di scharges undergo wastewater tr eatment (See Tables 10 and 14, Appendix D).Page 26 of 68 For maintenance applications at moderate -size cooling towers, assuming 360 days per year of release of blowdown water to surface wa ter and discharge of blowdown water untreated (Table 11, Appendix D), results based on the high-end scenario indicate:

 The endangered and acute COCs for freshwater inve rtebrates are exceeded one day or more at all application rates proposed on the product label.

 The endangered freshwater fish COC is exceeded one day or more at all application rates proposed on the product label and the acute COC fo r freshwater fish is exceeded for one day or more for all but the lowest application rate (0.5 ppm DTEA ae) proposed on the product label.

 The chronic COC for freshwater invertebrates (COC = 7.8 ppb) is exceeded for 20 days or more at the two highest application rates modeled (5.9 and 24.4 ppm DTEA ae).

 The chronic COC for freshwater fish (COC = 36.5 ppb) is exceeded for 20 days or more at the highest application rate (24.4 ppm D TEA ae) proposed on the product label.
For maintenance applications at moderate -size cooling towers, assuming 360 days per year of release of blowdown water to surface water and discharge of blowdown water following wastewater treatment (93% removal of DTEA via sorption to activated sludge during wastewater treatment) (Table 15, Appendix D, results based on the high-end scenario indicate:

 The endangered and acute COCs for freshwater inve rtebrates are exceeded one day or more at all application rates proposed on the product label.

 The endangered freshwater fish COC is exceeded one day or more at all application rates proposed on the product label and the acute COC fo r freshwater fish is exceeded for one day or more for all but the lowest application rate (0.5 ppm DTEA ae) proposed on the product label.

 The chronic COC for freshwater invertebrates (COC= 7.8 ppb) is exceeded for 20 days or more at all but the lowest application rate (0.5 pp m DTEA ae) proposed on the product label.

 The chronic COC for freshwater fish (COC = 36.5 ppb) is exceeded for 20 days or more at the highest application rate (24.4 ppm D TEA ae) proposed on the product label.
As a result of initial applications to fouled systems, releases to surface water are expected to be episodic and occur for one day per initial application. In the cas e of initial treatment scenarios, modeling was performed to determine whether or not there would be exceedance of COCs for one day of discharge. All high-end scenarios modeled for initial treatment predicted exceedances of at least some COCs for one day. For the high-end scenario for large-size cooling towers with no treatment, all COCs were predicted to be exceeded for the one day of discharge at all application rates proposed on the product label.. For the hi gh-end scenario for large-size cooling towers with 93 percent re moval during wastewater treatment , all COCs were exceeded at all application rates proposed on the label with the exception of the acute COC for freshwater fish at the lowest application ra te (20.4 kg/site/day). For the hi gh-end scenario for moderate-size cooling towers with 93 percen t removal during wastewater tr eatment, only the COC for the endangered freshwater invertebrate was exceeded at the higher two of three application rates proposed on the product label. Of the four average case scenarios modeled for initial treatment,Page 27 of 68 only for the scenario for the la rge-size cooling tower with no wastewater treatment were exceedances of COCs predicted for one day for some aquatic organisms.

There is a potential for acute and chronic risks to terrestrial wildlife that ingest fish and shellfish from bioaccumulation under the high end use with no pretreatment prior to discharge. There is a large degree of uncertainty in this portion of the assessment because the concentrations of DTEA expected under this scenario would be acu tely lethal to a wide variety of species, which would impact actual levels of DTEA in the food chain. With wastewater treatment prior to discharge acute risks to terrestrial wildlife are not likely. There is some uncertainty regarding chronic effects.

4.5.1 Effect of Exposure Assumptions

4.5.1.1 Exposures and Risks to Aquatic Organisms to DTEA in the Dissolved Phase of the Water Column Potential exposures and risks to DTEA from releases of blowdown water from recirculating cooling towers to surface water were examined for the following circumstances:

 Initial treatments for fouled systems versus maintenance treatments;

 Large-size versus moderate size recirculating cooling towers;

 High-end versus average case scenarios from E-FAST; and

 Wastewater treatment versus no wastewater treatment prior to discharge of blowdown water to surface water.
The magnitude of exposure of aquatic organisms to releases of recirc ulating cooling tower blowdown water to surface water is directly correlated with th e product application rate. The application rate of DTEA propos ed on the product label can be higher for initial treatment of fouled systems than for maintenance treatmen t: 6 to 41 fluid ounces of product per thousand gallons for initial treatment compared with 0.5 to 25 fluid ounces per thousand gallons for maintenance treatment. The duration of exposure to aquatic organisms from releases to surface water from initial treatment of fouled systems, however, would be expected to be much shorter than that for maintenance treatment. For modeling purposes, releases from blowdown water following initial treatment applications were assu med to be one day per initial treatment episode, whereas releases from blowdown water following maintenance treatment applications were assumed to occur on a daily basis (360 days per y ear). The annual frequenc y of initial treatment applications is expected to vary from site to site depending upon the rate at which a system can become fouled; this annual frequency can generally be expected to be considerably less than that for maintenance treatment.

For the maintenance treatment levels (disch arge of 360 days per year), there are some exceedances of concentrations of concern for aqua tic organisms for all scenarios examined. In summary, with regard to maintenance treatment th e estimated number of days of exceedance ofPage 28 of 68 concentrations of concern (COCs) for aquatic organisms increase as environmental releases increase for maintenance treatment and are:

 Higher for large-size cooling towers th an for moderate-size cooling towers;

 Higher for recirculating cooling towers that di scharge blowdown water without treatment than those that discharge blowdown water following wastewater treatment; and

 Higher for the high-end scenario than the average case scenario.

These same trends are observed when es timating whether or not concentrations of concern for aquatic organisms are exceeded for on e day of release of blowdown water to surface water following initial treatment of fouled systems. In the case of initial treatment scenarios, modeling was performed to determine whether or not there would be exceedance of COCs for one day of discharge. Of the four average case scenarios modeled for in itial treatment, only for the scenario for the large-size c ooling tower with no wastewater treatment were exceedances of COCs predicted for one day for some aquatic or ganisms. All high-end scenarios modeled for initial treatment predicted exceedances of at l east some COCs for one day. For the high-end scenario for large-size cooling to wers with no treatment, all COCs were predicted to be exceeded for the one day of discharge at all application rates proposed on th e product label.. For the highend scenario for large-size cooling towers with 93 percent removal during wastewater treatment, all COCs were exceeded at all application rates proposed on the label with the ex ception of the acute COC for freshwater fish at the lowest appl ication rate (20.4 kg/site/d ay). For the high-end scenario for moderate-size cool ing towers with 93 percent rem oval during wastewater treatment, only the COC for the endangered freshwater invert ebrate was exceeded at the higher two of three application rates propose d on the product label.

Exposures to aquatic organisms from rel eases of blowdown water from large-size recirculating cooling towers were predicted to be higher than those for moderate-size cooling towers as a result of the much higher recircula tion rates assumed for la rge-size recirculating cooling towers than for moderate-size cooling to wers. The standard scenario developed by the Chemical Engineering Branch of the Office of Pollution Prevention and Toxics (OPPT/CEB) assumes that the recirculation rate is 2000 gallons per minute fo r moderate-size cooling towers and 100,000 gallons per minute for large-size coo ling towers. Consequently, environmental releases to surface water from recirculating cooling tower blow down water are estimated to be much higher for large-size cooling towers than for moderate-size cooling towers. Environmental releases of DTEA from mainte nance treatments can range from 1.7 to 84 kg/site/day for largesize cooling towers compared to 0.03 to 1.7 kg/ site/day for moderate -size cooling towers.

The Industrial Releases module of E-FAST was also used to examine the influence of the selection of Standard Industrial Classification (SIC) code on the m odeling results (See Table 5). The selection of SIC code influen ces the distribution of the ratio of stream flows to plant flows. The estimated number of days per year of exceeda nce of COCs for steam electric power plants were compared with those for industrialized POTWs at an environmental release of 2.8Page 29 of 68 kg/site/day assuming 93 percent re moval during wastewater treatme nt and 360 days per year of release for both average case and high-end scen arios. The Industrialized POTWs SIC code might be considered to be more representative of the ratio of stream fl ows to plant flows for moderate-size recirculating cooling towers. The results of this comparison predict that for both high-end and average case scenarios, the numbers of days per year of exceedance are fewer for the Industrialized POTWs SIC code than for the Steam Electric Powe r Plants SIC code at higher COCs (e.g., COC=110 ppb) modeled and greater fo r the Industrialized POTWs SIC code than for the Steam Electric Power Plants SIC c ode at lower COCs (e.g., COC = 10 and 1.7 ppb).

4.5.2 Uncertainties

4.5.2.1 Estimated Benthic Invertebrate Toxicity Values Sediment toxicity values were estimate d using the EqP approach. Since the water column testing used in the EqP approach does not include food that has accumulated DTEA, the estimated sediment toxicity values using the EqP approach will potenti ally underestimate this exposure pathway. Sediment ingestion for benthi c invertebrates is a cr itical exposure pathway for the guideline sediment tests. The result of this pathway not being included may result in underestimation of risk. Because the high-e nd scenarios were great ly over the estimated sediment toxicity values, this uncertain ty does not impact risk conclusions.

4.5.2.2 Bioaccumulation/Bioconcentration in Fish and Shellfish
Bioconcentration and bioaccumulation in fish and shellfish were estimated because of the lack of a fish and mollusk bioconcentration stud y. Biotransformation can play a major role in the mitigating estimations of bioconcentration and bioaccumulation. The degree of this impact is unknown in this case. EPI Suite provided some estimates of biotransformation for the BAF and BCF values used in the assessment and these were used in assessing risks.

4.5.2.3 Aquatic Plant Toxicity Data For this use pattern a battery of three alga l species (green algae, freshwater diatom, saltwater diatom), in addition to a cyanob acteria, a floating macrophyte (duckweed), and a seedling emergence test for an emergent, ro oted macrophyte (rice) re presenting different sensitivities and environmental habi tats are used to assess risk fo r the recirculating process water system use pattern. Only a green algae study wa s submitted and no public literature studies were found. Because DTEA is the only member of this cl ass structure currently registered in the U.S., there was no possibility of using submitted toxicity data from closely-related surrogate chemicals to fill in these data gaps. The availability of just the green algae data may result in underestimation of risks for aquatic plants. For th e high-end exposures evalua ted the lack of this data does not change the risk conclusions. Howe ver, at the lower use rates this potentially introduces a large degree of uncertainty wher e COCs are not exceeded for aquatic plants.Page 30 of 68 

### 4.6 Endangered Species Assessment Section 7 of the Endangered Species Act, 16 U.S.C. Section 1536( a)(2), requires all federal agencies to consult with the National Ma rine Fisheries Service (NMFS) for marine and anadromous listed species, and/or the United States Fish and Wildlife Service (USFWS) for listed wildlife and freshwater organisms, if they are proposing an "action" that may affect listed species or their designated critic al habitat. Each federal agen cy is required under the Act to ensure that any action they aut horize, fund, or carry out is not likely to jeopardize the continued existence of a listed species or result in the destruction or adverse modification of designated critical habitat. To jeopardize the continued existence of a listed species means "to engage in an action that reasonably would be expected, directly or indirect ly, to reduce appreciably the likelihood of both the survival and recovery of a listed species in th e wild by reducing the reproduction, numbers, or distribution of the species" (50 C.F.R. § 402.02).

To facilitate compliance with the requir ements of the Endangered Species Act (subsection (a)(2)), the Office of Pesticide Programs has establis hed procedures to evaluate whether a registration action may di rectly or indirectly apprecia bly reduce the likelihood of both the survival and recovery of a listed species in the wild by re ducing the reproduction, numbers, or distribution of any listed sp ecies (USEPA, 2004). After the Agency’s screening level risk assessment is conducted, if any of the Agency’s listed species’ LOCs are exceeded for either direct or indirect effect s, an analysis is conducte d to determine if any lis ted or candidate species may co-occur in the area of the pesticide use or areas downstream or downwind that could be contaminated from drift or runoff/erosion. If lis ted or candidate species may be present in the proposed action area, further biological assessmen t is undertaken. The extent to which listed species may be at risk is considered, which then determines the need for the development of a more comprehensive consultation package, as required by the Enda ngered Species Act.

The federal action addressed herein is the proposed registration review of DTEA-HCl for use in recirculating cooling to wers and it is expected that its use could occur nationwide.

4.6.1 Action Area For listed species assessment purposes, the action area is considered to be the area affected directly or indirectly by DTEA-HCl us e and not merely the immediate area where it is applied. At the initial screening-level, th e risk assessment considers broadly described taxonomic groups and conservatively assumes that listed species within those broad groups are co-located with the pesticide trea tment area. This means that listed terrestrial plants and wildlife are assumed to be located on or adjacent to the treated site (cooling towe r) and listed aquatic organisms are assumed to be located in a surf ace water body adjacent to the treated site (cooling tower). The assessment also assumes that the list ed species are located within an assumed area, which has the relatively highest po tential exposure to the pesticide, and that exposures are likely to decrease with distance from the treatment area.Page 31 of 68 4.6.2 Taxonomic Groups Potentially at Risk The screening level COCs provided in this assessment would indicate a potential for a "may affect" conclusion for direct effects on aq uatic listed species and may extend to indirect effects upon listed species that depend upon that a particular taxonomic group as a resource. In such cases, additional information on the biology of listed species, th e locations of these species, and the locations of use sites are considered to determine the extent to which screening assumptions regarding an action area apply to a particular listed organism. These subsequent refinement steps will consider how this informa tion would impact the action area for a particular listed organism and potentially include areas of exposure that are downwind and downstream of the pesticide use site.

4.6.3 Listed Species Occurrence Associated with DTEA

‐ HCl Use The screening-level risk assessment for DTEA-HCl assumes that it may be applied nationwide, including U.S. te rritories and possessions, unles s spatially limited by label. Therefore, no federally listed species are excluded from the screening level analyses, unless otherwise indicated (e .g., if only listed due to Si milarity of Appearance to another listed species). A spatial co-occurrence analysis that compares the best available data regarding DTEA-HCl potential and documented use areas and listed species occurrence is needed to more explicitly address potential risk to li sted species of concern.

At this stage of the Registration Review process, it is premature to make effects determinations for listed species until further refinements are conducted. In order to make effects determinations for indivi dual species, useful refinements ma y include analyses of 1) more detailed, species-specific eco logical and biological data; 2) more detailed and accurate information on DTEA-HCl use patterns; and 3) su b-county level spatial pr oximity data for the co-occurrence of potential effects areas and listed species and any designated critical habitat.

Refinements may include more detailed anal yses of the registered uses and their use patterns that result in LOC exceedances for fede rally listed species in the screening-level assessment. The analyses may include more information on where, when, and how DTEA-HCl is used.

In addition, On April 30, 2013, the National A cademy of Sciences’ National Research Council (NRC) released their recommendations for assessing risks from pesticides to listed species under the Endangered Species Act (ESA ) and the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). The Environmental Protection Agency, the U.S. Department of Agriculture, the U.S. Fish and Wildlife Servi ce, and the National Marine Fisheries Service are working collaboratively to identify improvements in the current scientific procedures used in evaluating the potential impacts of pesticid es to endangered and threatened species.Page 32 of 68 

### 5.0 SUMMARY OF RISKS

DTEA-HCl is currently not marketed in the US and therefore, all estimated exposures are theoretical. However, if DTEA-HCl is marketed in the fu ture, EPA believes that risks to human health from the use of DTEA-HCl are ex pected to be minimal based on current labels.

Risks to non-target birds and mammals are also expected to be minimal. There is a potential risk to birds that consum e fish that are exposed to releas es from large towers treated at the maximum treatment rate without wastewater treatment prior to release. This risk is highly uncertain.

There are potential risks to al l aquatic organisms from releases of cooling tower waters including releases of water which has been treated in a wastewater treatment facility prior to release. Aquatic invertebrates and algae are more sensitive to DTEA than are freshwater fish, but all aquatic organisms would be affected if a release occurs. Maintenance treatments which result in daily releases are expected to result in greater risks than initial treatments that result in single (one time) release.

Benthic organisms would be exposed to DTEA as it sorbs to sediment. Chronic risks are estimated for treatments of large towers and high rates with no ch ronic risks for benthic organisms from moderate size to wers treated at low rates.

There are several uncertainties associated wi th this risk assessment. On the hazard assessment, EPA made conservative assumptions ba sed on the lack of definitive toxicity data on benthic organisms, estuarine and marine organisms, aquatic plants and chronic data for birds. For the exposure assessment, lack of aquatic metabolism data and bioaccumulation data on fish and shellfish resulted in cons ervative exposure assumptions.Page 33 of 68 

### APPENDIX A: Environmental Fate

When DTEA·HCl is added to water, it di ssociates into DTEA and HCl. Table 6 summarizes studies on DTEA·HCl and its major reaction product DTEA which were submitted and reviewed prior to the FWP, and those submitte d and reviewed in response to the GDCI. The studies requested as part of GDCI were a ready biodegradabili ty study and an activated sludge respiration inhibition (ASRI) study. Both were re viewed and accepted. Changes in models used to estimate some property and fate characterist ics in the FWP have been updated, so the latest model versions were run and these values have also been updated in Table 6.

Since the FWP, additional exposure pathways have been identified for the recirculating cooling system use pattern which needed to be considered in this assessment given DTEA properties and fate in the aquatic system. Bio accumulation was identified as a potential exposure route as log K ow values for DTEA are above 3 and DTEA is not rapidly degraded. Because no bioconcentration study was required at the time of the FWP, bioconc entration factors (BCFs) and bioaccumulation factors (BAFs) were estimated for DTEA and are included in Table 6. Sediment exposure of benthic inve rtebrates to DTEA was identified as a potential exposure route of concern based on estimated soil orga nic carbon-water partition coefficient (K oc ) and soil sorption (K d ) values. The Agency used this information to characterize concentrations in sediment below recirculating coo ling water systems in Section 4.2.1.1.

Table 6. Physical/Chemical Characteristics a nd Environmental Fate Studies and Results

GLN: Study Type MRID#: Reference Study Summary Results, Conclusions, and Study Classification

835.2110: Hydrolysis of DTEA as function of pH MRID# 40126404: Fate of N

-decythioethylamine in the environment by Gonsoir S (1986) Report# ES-DR 0065- 5425-1; prepared, submitted by Dow Chem. Co. Percent purity of the active ingredient: 99.8. Study was conducted under sterile, and buffered medium at pH 5(acetate), pH 7 (phosphate), and pH 9 (borate). The active ingredient in acetonitrile was added @ 3.8 ppm level and 25 ± 0.5 o C. Samples were collected, diluted and analyzed by using reverse phase ion exchange HPLC. The detection limit was 0.1 ppm Hydrolytic half life was estimated at 66 days (pH 5), 480 days (at pH 7) and 360 days (at pH 9).

The study is classified as ACCEPTABLE for pH 5, and 7, but as SUPPLEMENTAL for pH 9. The data at pH 9 was ambigous, and a second study was requested, and the registrants submitted a separate study on pH 9, as discussed below.

DTEA is persistent at these pHs under abiotic conditions.Page 34 of 68 GLN: Study Type MRID#: Reference Study Summary Results, Conclusions, and Study Classification

835.2110: Hydrolysis of DTEA as a function of pH MRID# 41198301: Gonsior, S, 1989) study submitted by Dow Chem Co. : Hydrolysis at pH 9 on the N

decylthioethaneamine hydrochloride with C-14 radiolabeled at position 2 Study ID: ES-DR-0224- 8182-2 The solution was buffered at pH 9 and ai at 6.8 ppm with ai being at 92% purity.

Percent recovery: 93% of the C-14 activity after 28 days means that there was no loss due to adsorption on the walls, or possible formation of volatiles. DTEA undergoes transformation at pH 9, in 0.01 M borate solution. Half life estimated at 30 days. Thus at pH 9, the half life is considered bord erline stable in water under abiotic conditions. Study is classified as ACCEPTABLE.

835.1110: Activated Sludge Sorption Isotherm for DTEA MRID# 49004201: Submitted by Dow Chem. Co. Study ID# 120010; conducted by Schaefer, EC, and Ponizovsky, AA. Samples of the ai (DTEA) were prepared with the activated sludge solids at concentrations of 0.05, 0.10, 0.30, 0.50 and 0.90 g/L in
p hosphate buffer and at pH 7.3. The concentrations of the activated solids ranged from 0.05 to 0.92g/L. The inoculum of the activated sludge was collected from the wastewater treatment plant in Cambridge, MD. The sludge was pretreated and in the final stage, and consisted of 37.78% organic carbon. The active (DTEA) adsorbed to the activated sludge ranged from 93.2-98.5% of the applied. The K d (av) = 8148 ml/g; Koc = 21566 ml/g

The Koc and or Kd values strongly indicate that DTEA is immobile and will stay on activated sludge surfaces. The microbes present are not affected by this active.

The study is classified as ACCEPTABLE.

OECD Test guideline No. 209: Activated Sludge Respiration Inhibition Test for DTEA MRID# 41198306: Conducted by Davis, JW, and Madsen, SS, 1989: Activated Sludge, Inhibition Test for 2- decylthioethaneamine. Submitted by Dow Chem.Co. The study measures the concentration of the active at which oxygen consumption is inhibited at a 50% rate. The IC 50 in this study was determined to be 27 ppm for the active.

The IC 50 for the reference substance (3,5-dichlorophenol) was measured to be 17 mg/L. The IC 50 for the reference material should be between 5- 30 mg/L. Also if the active has an IC 50 value above 30 mg/L, then this substance would be highly toxic. The IC 50 value measured was 27 mg/L, thus it within the safe limit of IC 50 for conduct of a ready biodegradability study.

The study was deemed SUPPLEMENTAL as some raw data were missing.

OECD Guideline 301D: BOD Closed Bottle TEST for Ready Biodegradability (Equal to: 835.3110) for DTEA MRID# 49004202: Submitted by Dow Chem. Co; Study ID# 121050; Study conducted by Gonsior, S and Holzheur, WB. Closed Bottle Test was conducted on the ai in the presence and absence of silica gel, over a period of 28 days. The microbial inoculum was a secondary effluent from a wastewater treatment plant which was preconditioned by filtration and dilution with mineral medium. The temperature was maintained at The test material did not reach pass levels of 60% of theoretical oxygen demand as the degradation was 43.5% and 29.3 % for samples of DTEA at 1.6 mg/L and 3.1 mg/L respectively after 28 days o f the study.

DTEA is NOT ready biodegradable. Thus underPage 35 of 68 GLN: Study Type MRID#: Reference Study Summary Results, Conclusions, and Study Classification 21 ± 0.5 o C and the samples were kept in darkness. biotic conditions too, it is stable.

The study was classified as ACCEPTABLE.

835.1230: Log soil organic carbon-water partition coefficient (Log K oc ) for DTEA Estimated using EPI Suite, version 4.11) Not applicable. 3.992 (K oc = 9,810)

The value shows that the DTEA has a strong tendency to bind to soils. The high value of Log Koc for soils and activated sludge (see above) is a strong indication that DTEA remains on soil surfaces and not migrate to ground water. (It is immobile).

K d for DTEA Equilibrium Partitioning Sediment Benchmarks (EPA 600/R-02- 2012) K d = K oc x f oc where f oc = mass fraction of soil organic carbon content. Not applicable. 0.02% f oc K d = 19.62 1% f oc K d = 98.1 5% f oc K d = 490

The K oc and K d values mean DTEA is expected to partition to suspended particles and sediment in an aquatic system.

Henry Law Constant for DTEA Estimated using EPI Suite (version 4.11); no test guidelines; it is calculated based on the vapor pressure and the solubility of a substance in water Not applicable. 2.76 x 10 -5 atm-m 3 / mole

Borderline value indicates the possibility of volatilizing from water surfaces is moderately high. Volatilization from water surfaces will reduce the surface water concentration of DTEA.

830.7950: Vapor pressure for DTEA EPI Suite, version 4.11 Not applicable. 7.97 x 10 -4 mm Hg

Considered moderately volatile. Will volatilize from water surfaces in moderate measures into the atmosphere.

Non-Guideline: Half life in air for DTEA Estimated using EPI Suite version 4.11, estimated against the hydroxyl radical reaction 4.1 hours

Will degrade quickly and not persist in air. No data is available on the possible degradate formed and or the identity of the degradate in the air. DTEA is NOT stable in air. 830.784: Water solubility for DTEA 40126403 The Kow determinations, along with the solubility of 0.0035 g/100 g at 25 o C. (30.5 mg/L at 25 o C)Page 36 of 68 GLN: Study Type MRID#: Reference Study Summary Results, Conclusions, and Study Classification

830.1755: Log wateroctanol partition coefficient (Log Kow) for DTEA·HCl and DTEA. DTEA·HCl and DTEA were done by using shake flask and generator column methods as suggested in the test guideline. Kow measurements were done in HPLC grade water, and also in buffered water (pH 7). DTEA·HCl : 2.35 (approx.) using HPLC grade water

DTEA : 3.72 (mean) using HPLC grade water

3.05 (mean) using pH 7 buffered water

Indicates potential for bioaccumulation of DTEA in aquatic organisms.

850. 1730 Fish Bioconcentration Factor (BCF) and Bioaccumulation Factor (BAF) in units of L/kg-wet-weight for DTEA EPISuite v4.11 Arnot-Gobas BCF & BAF Methods Not applicable Assumes a biotransformation rate of zero : BCF (upper trophic) = 2264 BAF (upper trophic) = 8863

Includes estimated biotransformation : BCF (upper trophic) = 516.5 BAF (upper trophic) = 518 BCF (mid trophic) = 572.3 BAF (mid trophic) = 585.9 BCF (lower trophic) = 575.8 BAF (lower trophic) = 623.3

APPENDIX A REFERENCES

EPI Suite, version 4.11

MRID# 40126404: Gosnoir, S, 1986. Fate of N -decylthioethylamine in the Environment; Test Guideline 835.2110, Hydrolysis as a function of pH, Submitted by Dow Chemical Co.

MRID # 41198301: Gosnoir, S, 1989. Hydrolysis of DTEA at pH 9, Test guideline 835.2110, submitted by Dow Chemical Co.

MRID#: 41198301, Gonsoir, S, 1989: Hydrolysis at pH 9 on N -decylthioethanemaine hydrlochloride with C-14 radiolabeled at position 2; submitted by Dow Chem. Co

MRID#: 49004202: BOD Closed Bottle Test for Rea dy Biodegradability, Test guideline # 301D, submitted by Dow Chemical Co.Page 37 of 68 

### APPENDIX B: Summary of Ecotoxicity Data for DTEA

Terrestrial Studies: DTEA was found to be practically non–toxic to birds based on acute toxicity testing of Mallard Duck (LD 50 = >2250 mg/kg), and dietary toxicity testing of both Bobwhite Quail (LC 50 =>5620 mg/kg) and Mallard Duck (LC 50 =>5620 mg/kg).

Aquatic Studies: DTEA was found to be high ly toxic to ra inbow trout (LC 50 = 770 ppb), bluegill sunfish (LC 50 = 700 ppb), and flathead minnow (LC 50 = 220 ppb). Daphnid toxicity testing indicated that DTEA is very highly to xic to freshwater aquatic invertebrates (LC 50 = 34 ppb). Chronic toxicity testing indicated that DTEA was very highly toxic to both freshwater invertebrates (LOAEC = 13.4 ppb) and fathead minnow (LOEAC = 36. 5 ppb) (Table 7).

There was aquatic plant study submitted, a green algae study (MRID 49004203) and it does not provide a definitive IC 50 or NOAEC value. At all te sted treatment levels the % inhibition was <50% and there was no affect at the highest treatment level as compared to controls. All DTEA degraded below detection limit by end of test so a weighted average, assuming exponential decay cannot be calculated. The study contains only sufficient information to identify that the IC 50 based on initial measured exposure co ncentrations is expected to be > 11.7 ppb. The Agency uses initial exposure concen tration for algae tests under such conditions. The NOAEC can be stated as > 11.7 ppb.

For this use pattern a battery of three alga l species (green algae, freshwater diatom, saltwater diatom), a cyanobacteria and a floati ng macrophyte (duckweed), re presenting different morphological characteristics and environmental habitats are used to assess risk for the recirculating cooling system use pattern. Becau se DTEA is the only member of the class of currently registered in the U.S., there is no pos sibility of using submitted toxicity data from closely-related surrogate chemicals to fill in potential data gaps.Page 38 of 68 Table 7 Ecotoxicity Data for DTEA·HCl and DTEA

Guideline No./

Study Type MRID No./ Reference Information/

Study Classification Dosing and Animal Information Results

Aquatic Fauna 850.1010 Aquatic invertebrate acute toxicity test, freshwater daphnids and 850.1300 Daphnia sp. Life Cycle MRID 41198303, 41198305, 41512602, 41779901 Gersich, F.; Milazzo, D.; Voos-Esquivel, C. (1988)An Invertebrate LifeCycle Study of the Toxicity of 2-(Decylthio)-ethanamine Hydrochloride (DTEA·HCL) to Daphnia magna Straus:Project Study ID: ES-DR0065-5425-6. Unpublished study prepared by Dow Chemical Co. 23 p. Supplemental Purity 100.6% of ai Daphnia magna used were < 24 hours old. 5 neonates/ replicates, 4 replicates/test concentration. Test durations were 21day life cycle, flowthrough system and a 48 hours study. Measured test concentrations were 7.8, 13.4, 24.8, 44.8, 84 μg/l Nominal test concentrations were 1, 2, 3, 4, and 5 μg/l 21-day LC 50 = 0.033 mg/l 48–hour LC 50 = 0.028 mg/l (mean measured concentrations)

Maximum Acceptable Toxicant Concentration (MATC) for 21-days > 7.8 and < 13.4 μg/l mean measured concentrations; Geometric mean MATC = 10.2 μg/l.

850.1010 Aquatic invertebrate acute toxicity test, freshwater daphnids MRID 40126416, 42482901 Dill, D.; Milazzo, D.; Barlett, E.; et al. (1985) Evaluation of the Toxicity of N -decylthioethylamine to Representative Aquatic Organisms: Report No. ES-805. Unpublished study prepared by Dow Chemical U.S.A. 27 p. Supplemental Purity 99.8% of ai Daphnia magna 10 daphnids/ replicate, 3 replicates/test concentration. Test measured concentrations were 0.0078, 0.013, 0.022, 0.036, 0.06, and 0.1 mg/l. 48 – hours LC 50 (95% C.I.) = 0.034 (0.030 - 0.038) mg/l (measured concentration)

850. 1075 Fish acute toxicity

test, freshwater

and marine MRID 40126416, 42482901 Dill, D.; Milazzo, D.; Barlett, E.; et al. (1985) Evaluation of the Toxicity of N -decylthioethylamine to Representative Aquatic Organisms: Report No. ES-805. Unpublished study prepared by Dow Chemical U.S.A. 27 p. Supplemental Purity 99.8% of ai Bluegill Sunfish ( Lepomis macrochirus ) 10 fishes/test concentration Test concentrations were 0.08, 0.13, 0.22, 0.36, 0.6, and 1 mg/l. 96 – hours LC 50 (95% C.I.) = 0.70 mg/l (0.36– 1 mg/l)Page 39 of 68 Guideline No./

Study Type MRID No./ Reference Information/

Study Classification Dosing and Animal Information Results

850. 1075 Fish acute toxicity

test, freshwater

and marine MRID 40126416, 42482901 Dill, D.; Milazzo, D.; Barlett, E.; et al. (1985) Evaluation of the Toxicity of N -decylthioethylamine to Representative Aquatic Organisms: Report No. ES-805. Unpublished study prepared by Dow Chemical U.S.A. 27 p. Supplemental Purity 99.8% of ai Rainbow trout ( Salmo gairdneri ) 10 fishes/test concentration Test concentrations were 0.08, 0.13, 0.22, 0.36, 0.6, and 1 mg/l. 96 – hours LC 50 (95% C.I.) = 0.77 (0.60 – 1) mg/l

850. 1075 Fish acute toxicity

test, freshwater

and marine MRID 40126416, 42482901 Dill, D.; Milazzo, D.; Barlett, E.; et al. (1985) Evaluation of the Toxicity of N -decylthioethylamine to Representative Aquatic Organisms: Report No. ES-805. Unpublished study prepared by Dow Chemical U.S.A. 27 p. Supplemental Purity 99.8% of ai Fathead minnow (Pimphales promelas) 10 fishes/test concentration Test concentrations were 0.08, 0.13, 0.22, 0.36, 0.6, and 1 mg/l. 96 – hours LC 50 (95% C.I.) = 0.22 (0.13 – 0.36) mg/l

850.1400 Fish early-life stage toxicity test MRID 41198302, 41198304, 41512601, 41779902 Dill, D.; Mayes, M.; Bartlett, E.; et al. (1988)2-(Decylthio)ethanamineHydrochloride: EmbryoLarval Toxicity Test with Fathead Minnow, Pimephales promelas rafinesque: Project Study ID: ES-DR-0065-5425-7. Unpublished study prepared by Dow Chemical Co. 26 p. Core Purity 100.6% of ai Embryos of fathead minnow (Pimphales promelas) 35 embryos (< 24 hours old) were impartially distributed to each incubation cup; 140 embryos/test. 31 day embryo-larval flow through test. Test concentrations were 12, 18, 27, 42, 65, and 100 μg ai/l Mean measured concentrations were 14.5, 23.3, 38.8, 58.4, and 93.1 μg ai/l. NOEL = 0.0233 mg/l. Maximum Acceptable Toxicant Concentration (MATC), based on body weight, mean measured concentration lies between 0.0233 and 0.0383 mg/l. Geometric mean MATC = 0.0301 mg/l.Page 40 of 68 Guideline No./

Study Type MRID No./ Reference Information/

Study Classification Dosing and Animal Information Results

Terrestrial Wildlife 850.2100 Avian acute oral

toxicity test MRID 40126412 Beavers, J. (1986) N

decylthioethylamine: An Acute Oral Toxicity Study with the Mallard: Dow Report No. ES-DR-0065-5425-5: Contract Project No. 103- 243. Unpublished study prepared by Dow Chemical U.S.A. in cooperation with Wildlife International Ltd. 20 p. Core Purity 99.8% of ai Mallard duck ( Anas platyrhynchos ) were 17 weeks old. Groups of 10 birds/per concentration. Test duration was 14 days. Test concentrations were 2250, 1350, 810, 486, 292 ppm via intubation. LD 50 > 2250 mg/kg. NOEL = 292 mg/kg At 810, 1350, and 2250 mg/kg groups birds exhibited eye irritation and clouding which cleared up in all groups by the end of the third day.

850.2200 Avian dietary toxicity test MRID 40126414, 40126413 Beavers, J. (1986) N

decylthioethylamine: A Dietary LC50 Study with the Mallard: Dow Report No. ES-836: Contract Project No. 103-242. Unpublished study prepared by Dow Chemical U.S.A. in cooperation with Wildlife International Ltd. 20 p. Core Purity 99.8% ai Mallard Duck ( Anas platyrhynchos ) were 10 days old. Groups of 10 ducklings were randomly assigned to each of the five control and five treatment groups. Test duration was 8 days Test concentrations were 562, 1000, 1780, 3160, and 5620 ppm via diet. DTEA is non-toxic to Mallard ducklings. LC 50 > 5620 ppm. NOAEC = 1780 ppm At 3160 ppm, lethargy was observed on days 4 and 5. At 5620 ppm, signs of toxicity reported were lethargy, reduced reaction to external stimuli, loss of coordination, prostrate posture, loss of righting reflex, and lower limb weakness. 850.2200 Avian dietary toxicity test MRID 40126415, 40126413 Beavers, J. (1986) N

decylthioethylamine: A Dietary LC50 Study with the Bobwhite: Dow Report No. ES-DR-0065-5425-3: Contract Project No. 103- 241. Unpublished study prepared by Dow Chemical U.S.A. in cooperation with Wildlife International Ltd. 19 p. Core Purity 99.8% ai Bobwhite quail (Colinus virginianus) were 10 days old Groups of 10 chicks were randomly assigned to each of the five control and five treatment groups. The duration of test was 8 days. Test concentrations were 389, 1000, 1780, 3160, 5620 ppm via diet. DTEA is non toxic to bobwhite quail chicks. LC 50 > 5620 ppm. NOAEC = 3160 ppm At 5620 ppm, slight reduction in body weight gain was observed.Page 41 of 68 Guideline No./

Study Type MRID No./ Reference Information/

Study Classification Dosing and Animal Information Results

Acute oral rat study MRID 40126405 Jeffrey, M.; Schuetz, D.; Lomax, L. (1986) 2- (Decylthio)ethanamine: Acute Oral Toxicity Study in Fischer 344 Rats: Report No. HET DR-0065-5425-001A. Unpublished study prepared by Dow Chemical U.S.A. 17 p. Purity 99.8% DTEA 7 wk-old Fischer 344
rats 6 rats/sex/dose; Dose levels: 1300, 2500 or 5000 mg/kg-bw; Single dose gavage using corn oil carrier LD 50 = 2272 mg DTEA/kg-bw (females) LD 50 = 3940 mg DTEA/kg-bw (males)

Benthic Invertebrates

No benthic invertebrate sediment toxicity data for DTEA was submitted or found in the open literature. Neither was any sediment toxicity data for a chemical from the same chemical structural activity group submitted or found. Th erefore, an equilibrium partitioning (EqP) approach was used to derive a bulk sediment toxi city value from water-onl y DTEA toxicity data. This method will not account for uptake and exposu re from ingestion of the sediment, and may therefore underestimate sediment toxicity to so me degree. The EqP approach is based on an assumption of chemical equilibrium between the solid phase of sediment and the sediment pore (interstitial) water and that the effect concentration in water-only exposure will be similar to the effect concentration in the sediment pore water. In this method any wa ter-only toxicity data value can be used; the approach is not limited to any single ef fect endpoint. The derived sediment toxicity data is expect ed to be commensurate with the given level of protection of the species, exposure, and endpoint (e.g., acute or ch ronic). The EqP model used is described in Equations 1 through 4. The EqP method is applicable to sediments with f oc >0.2% but not <0.2%. Factors controlling second-order partiti oning (e.g., particle size, sorption to nonorganic mineral fractions) become relatively more im portant than organic carbon content at f oc <0.2%. A sediment invertebrate NOAEC, expressed as mill igram of chemical per kilogram of sediment (mg/kg sed ), is estimated from a water-only chronic va lue for an invertebrate using Equations 1 through 3, results are provided in Table 8.

wo p s NOAEC K NOAEC   Equation 1 where:

NOAEC wo = water-only chronic NOAEC value for an invertebrate in units of mg/L;

oc oc p K f K   = organic carbon binding of a chemical in sediment; Equation 2

f

oc = weight or mass fraction of organic carbon in the sediment (kg organic carbon (oc)/kg of bulk sediment); andPage 42 of 68 K

oc = organic carbon normalized soil-water partiti on coefficient (ratio of the concentration in water to the concentration in so il organic carbon (oc)) in units of mg/kg-sediment oc per mg/L solution or L solution/kg-sediment oc), which is expected to be a constant for each chemical. The sediment K oc for DTEA is estimated as 9,810 L/kg (see Table 6). The activated sludge Koc was measured to be 21,566 L/kg (Table 6).

The sediment toxicity value will differ ba sed on the organic carbon content of sediment. The expression of the sediment toxicity valu e can be normalized on a sediment organic carbon basis, expressed in units of milligrams of chemical per gram of sediment organic carbon and normalizing to 1 gram of oc (0.001 kg/g):

wo oc oc s NOAEC K NOAEC    001

. 0

, . Equation 3

Table 8 Freshwater Benthic Invertebrate Toxicity

Chronic Invertebrate NOAEC wo Koc (L/kg) Chronic Invertebrate NOAEC s , oc Chronic Invertebrate NOAEC s (mg/kgsed) at f oc of: 0.2% 1% 4% 5% 0.0078 mg/L (lowest value, see Table 1and Table 7) 9810 0.0765 mg/g oc 0.15 0.77 3.1 3.8 21, 566 0.168 mg/g oc 0.34 1.68 6.7 8.4



### REFERENCES

Fuchsman PC. 2003. Modification of the equilibrium partitioning approach for volatile organic compounds in sediment. Envir on Toxicol Chem 22:1532-1534.

United States Environment Protection Agency (USEPA). 2003. Technical basis for the derivation of equilibrium partitioning sediment benchmarks (ESBs) for the protection of benthic organisms: nonionic organics. EPA-600-R-02-014. Office of Research and Development, Washington, DC, USA. (draft).

USEPA. 2007. Environmental Monitoring and Assessment Program (EMAP). Office of Research and Development, Washington, DC, USA ( www.epa.gov/emap ).

USEPA, 2008. Procedures for the Derivation of Equilibrium Partitioning Sediment Benchmarks (ESBs) for the Protection of Benthic Organi sms: Compendium of Tier 2 Values for Nonionic Organics. EPA/600/R-02/016. http://www.epa.gov/nheerl/download_files/ publications/ESB_Compendium_v14_final.pd f

USEPA, 2009. Summary of Product Chemistry, E nvironmental Fate, and Ecotoxicity Data for the 2-(Decylthio) ethanamine hydrochloride Registration Re view Decision Document. (Memo from Srinivas Gowda). 18 pp.Page 43 of 68 DTEA Literature Studies Not In cluded in ECOTOX: June 2013

1. Brady, Bonnie M. F. and Havel, James J. Formul ations of 2-(decylthio)ethanamine. 1993 Dec 7-(US1265H): 11 pp.

2. Dahanayake, Manilal and Paterson, Donald J. Formulation of stable water-based suspensions of mixtures of trihaloalkyl sulfone. 1991 Jan 27-(CA2000282A1): 22 pp.

3. Donofrio, Deborah K. and Whitekettle, Wilson K. Synergistic bactericidal mixtures of 2- (decylthio)ethanamine hydrochloride and 2-bromo-2-nitropropane-1,3-diol for Klebsiella pneumoniae. 1990 Apr 3-(US4914134A): 5 pp.

4. Elsmore, Richard and Houghton, Mark Phillip. B actericide combinations in detergents. 2001 Apr 4- (GB2354771A): 53 pp.

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5. Gerhold, Robert M.; Labine, Pa ul U.; Hwa, Chih M., and Fan, Grace L. Synergistic biocidal combinations for pulp and paper mills, petroleum operations, and cooling tower waters. 1996 May 17- (WO9614092A1): 34 pp.

6. Kumar, Pritesh Prakash. Searching for Novel Ligands for the Cannabinoid and Related Receptors. 2011.

7. Lazonby, Judy G.; McCarthy, Robert E., and Casselman, Nancy L. Method and compositions for inhibiting growth of microorganisms in wastewater. 1997 Aug 19-(US5658467A): 10 pp., Cont.-in-part of U.S. 5,494,588.

8. LaZonby, Judy G.; McCarthy, Robert E., and Casselman, Nancy L. Method and compositions for inhibiting growth of microorganisms including peracetic acid and a nonoxidizing biocide. 1997 May 21-

9. Ludensky, Michael; Hill, Christopher, and Lichtenb erg, Florian Christof Albrecht. Synergistic biocidal composition comprising a triamine. 2003 Jul 31-(WO2003062149A2): 18 pp.

10. McCoy, William F. and Hoots, John E. Method for use of compositions of biocides and fluorescent indicators to control microbial growth. 1997 Dec 30-(US5702684A): 14 pp., Cont.-in-part of U.S. Ser. No. 236,945, abandoned.

11. Petrille, Joseph C. III; Werner, Michael W., and Whitekettle, Wilson K. Detoxification of alkylthioalkylamines with swelling type natural or synthetic clays. 1997 Jan 21-(CA2174170A1): 12
pp.

12. Rimmer, Karen and Jamieson, Andrew Stephen. Stable biocidal solutions of dithiolane derivative mixtures with thioalkylamines. 1992 Jun 17-(GB2250737A): 14 pp.

13. Robertson, Linda R. Synergistic product selection test for biocides for industrial water treatment. 1994 Dec 20-(US5374536A): 11 pp. Cont.-in-part of U.S. Ser. No. 670,858, abandoned.Page 44 of 68 14. Toropov, A. A. and Benfenati, E. QSAR Models for Daphnia Toxicity of Pesticides Based on Combinations of Topological Parameters of Molecular Structures. 2006; 14, 2779-2788.

15. Unhoch, Michael Joseph; Choi, Sungmee; Roberts, Katherine P., and O'Malley, Leon Peter. Biocidal composition and method for treating recirculating water systems. 2008 Jun 19-(US20080142453A1): 15 pp.

16. Walter, Richard W. Jr.; Johnson, Robert L., and Re lenyi, Attila G. Control of biofouling in aqueous systems with certain alkylthioalkylamines. 1988 May 11-(EP266828A1): 11 pp.

17. Whitekettle, Wilson K. and Lyons, Larry A. Cont rolling macroinvertebrates utilizing decylthioethylamine. 1990 Nov 13-(US4970239A): 5 pp.

. 18. Whitekettle, Wilson Kurt; Tafel, Gloria Jean; Reynolds , Dorothy G.; Frail, Paul Robert; Wang, Linna; Jiang, Juan, and Zhao, Qing. Methods and vesicles for controlling protozoa in aqueous systems. 2011 Mar 3-(US20110052655A1): 8pp., Cont.-in-part of U.S. Ser. No. 835,717.

19. Whitekettle, Wilson Kurt; Tafel, Gloria Jean, and Zhao, Qing. Method for controlling microbial biofilm in aqueous systems. 2009 Feb 12-(WO2009020694A1): 21pp.; Chemical Indexing Equivalent to 150:221519 (US).

20. Whitekettle, Wilson Kurt; Tafel, Gloria Jean; Zhao , Qing; Wang, Linna; Reynolds, Dorothy; Frail, Paul; Jiang, Juan, and Polizzoti, David M. Methods and liposome carriers for controlling biofilms in aqueous systems. 2012 Apr 5-(WO2012044409A1): 27pp.

21. Whitekettle, Wilson Kurt; Tafel, Gloria Jean; Zhao , Qing; Wang, Linna; Reynolds, Dorothy; Frail, Paul; Jiang, Juan, and Polizzotti, David M. Methods and liposome carriers for controlling biofilms in aqueous systems. 2011 Mar 3-(US20110052656A1): 10pp., Cont.-in-part of U.S. Ser. No. 835,722.

22. Yin, Bei and Tinetti, Sheila M. Synergistic bi ocidal effect of 2-(decylthio)ethanamine and tetrakis (hydroxymethyl) phosphonium sulfate against Desulfovibrio. 2013 Mar 21-(WO2013039769A1): 13pp.

23. Yu, F. Philip and McCoy, William F. Use of the linear alkylbenzene sulfonate as a biofouling control agent. 1997 Sep 23-(US5670055A): 5 pp.

Referenced DTEA MRID Studies:

71-1 Avian Single Dose Oral ToxicityPage 45 of 68 MRID Citation Reference

40126412 (reviewed) Beavers, J. (1986) N -decylthioethylamine: An Acute Oral Toxicity Study with the Mallard: Dow Report No. ES-DR-0065-5425-5: Contract Project No. 103-243. Unpublished study prepared by Dow Chemical U.S.A. in cooperation with Wildlife International Ltd. 20 p.

71-2 Avian Dietary Toxicity
MRID Citation Reference
40126413 Gonsior, S. (1985) Investigation of the Stab ility of N-decylthioethylamine in Game Bird Starter Ration: Report No. ES-DR-0065- 5425-3,4. Unpublished study prepared by Dow Chemical U.S.A. 13 p.
40126414 Beavers, J. (1986) N -decylthioethylamine: A Dietary LC 50 Study with the Mallard: Dow Report No. ES-836: Contract Project No. 103-242. Unpublished study prepared by Dow Chemical U.S.A. in cooperation with Wildlife International Ltd. 20 p.
40126415 Beavers, J. (1986) N-decylthioethylamine: A Dietary LC 50 Study with the Bobwhite: Dow Report No. ES-DR-0065-5425-3: Contract Project No. 103-241. Unpublished study prepared by Dow Chemical U.S.A. in cooperation with Wildlife International Ltd. 19 p.

72-1 Acute Toxicity to Freshwater Fish
MRID Citation Reference
40126416 Dill, D.; Milazzo, D.; Barlett, E.; et al. (1985) Evaluation of the Toxicity of N -decylthioethylamine to Representative Aquatic Organisms: Report No. ES-805. Unpublished study prepared by Dow Chemical U.S.A. 27 p.
42482901 Dill, D.; Milazzo, D.; Bartlett, E. (1985) Supplemental Data Requested by EPA for Evaluation of the Toxicity of N -Decylthioethylamine to Representative Aquatic Organisms (MRID No. 40126416): Lab Project Number: ES-805. Unpublished study prepared by Dow Chemical Co. 32 p.

72-2 Acute Toxicity to Freshwater Invertebrates
MRID Citation Reference
40126416 Dill, D.; Milazzo, D.; Barlett, E.; et al. (1985) Evaluation of the Toxicity of N -decylthioethylamine to Representative Aquatic Organisms: Report No. ES-805. Unpublished study prepared by Dow Chemical U.S.A. 27 p.
42482901 Dill, D.; Milazzo, D.; Bartlett, E. (1985) Supplemental Data Requested by EPA for Evaluation of the Toxicity of N -Decylthioethylamine to Representative Aquatic Organisms (MRID No. 40126416): Lab Project Number: ES-805. Unpublished study prepared by Dow Chemical Co. 32 p.

72-4 Fish Early Life Stage/ Aquatic Invertebrate Life Cycle Study
MRID Citation Reference
41198302 Dill, D.; Mayes, M. ; Bartlett, E.; et al. (1988) 2-(Decylth io)ethanamine Hydrochloride: EmbryoLarval Toxicity Test with Fathead Minnow, Pimephales promelas rafinesque: Project Study ID: ES-DR-0065-5425-7. Unpublished study prepared by Dow Chemical Co. 26 p.
41198303 Gersich, F.; Milazzo, D.; V oos-Esquivel, C. (1988) An Invert ebrate Life-Cycle Study of the Toxicity of 2-(Decylthio)ethanamine Hydrochloride (DTEA.HCL) to Daphnia magna Straus: Project Study ID: ES-DR-0065-5425-6. Unpublished study prepared by Dow Chemical Co. 23 p.Page 46 of 68 41198304 Voos-Esquivel, C.; Murphy, P. (1988) 2-(D ecylthio)Ethanamine Hydrochloride : Determination in Standard Dilution Water for Acute and Chronic Flow-through Aquatic Toxicity Test with the Fathead Minnow Using High Performance Liquid Chromatography: Project Study ID: ES-DR-0065-5425-7. Unpublished study prepared by Dow Chemical Co. 35 p.
41198305 Voos-Esquivel, C. (1988) 2-(Decylthio)Ethan amine Hydrochloride: Determination in Standard Dilution Water for Chronic Flow- Through Aquatic Toxicity Test with the Daphnia magna Straus Using High Liquid Chromatography: Project Study ID: ES-DR-0065-5425-6-A. Unpublished study prepared by Dow Chemical Co. 30 p.
41512601 Dill, D.; Mayes, M.; Bartlett, E.; et al. (1988) Supplemental Data Requested by EPA for 2- (Decylthio)Ethanamine Hydrochl oride: Embryo-Larval Toxicity Test with Fathead Minnow, Pimephales promelas Rafinesque: Lab Project Number: ES-DR-0065-5425-7. Un- published study prepared by The Dow Chemical Co. 14 p.
41512602 Gersich, F.; Mil azzo, D.; Voos-Esquivel, (1988) Supplem ental Data Requested by EPA for an Invertebrate Life-Cycle Study of the Toxic ity of 2-(Decylthio)Ethanamine Hydrochloride (DTEA.HCL) to Daphnia magna Straus: Lab Project Number: ES-DR-0065-5425. Unpublished study prepared by Dow Chemical Co. 8 p.
41779901 Gersich, F.; Milazzo, D.; V oos-Esquivel, C. (1988) Supplementa l Data Requested by EPA for an Invertebrate Life-Cycle Study of the Toxicity of 2-(Decylthio) Ethanamine Hydrochloride (DTEA HCL) to Daphnia magna Straus--Final Report (Supplement to MRIDs 41198302, 41512601): Lab Project Number: ES-DR-0065-5425-6. Unpublished study prepared by Dow Chemical Co., Mammalian and Envir onmental Tox. Resear ch Lab. 21 p.
41779902 Dill, D.; Mayes, E.; Bartlett, E.; et al. (1988) Supple mental Data Requested by EPA for 2- (Decylthio) Ethanamine Hydrochloride: Embyro-Larval Toxicity Test with Fathead Minnow, Pimephales promelas Rafinesque--Final Report (Supplement to MRIDs 41198- 02, 41512601): Lab Project Number: ES-DR-0065-5425-7. Unpublished study prepared by Dow Chemical Co., Mammalian and Envir onmental Tox. Resear ch Lab. 31 p.

850.5400 Algal toxicity, Tiers 1 and II
MRID Citation Reference
49004203 Lehman, C.; Hutchison, K.; Malowinski, N. et al. (2012) DTEA: Growth Inhibition Test with the Green Alga, Pseudokirchneriella subcapitata . Project Number: 121042. Unpublished study prepared by Dow Chem ical Company. 51p.

Non-Guideline Study
MRID Citation Reference
42441401 Gersich, F.; Mil azzo, D.; Voos-Esquivel. (1988) Supplem ental Data Requested by EPA for an Invertebrate Life-cycle Study of the Toxicity of 2-(Decylthio) Ethanamine Hydrochloride (DTEA HCL) to Daphnia magna Straus: Lab Project Number: ES-DR-0065-5425-6. Unpublished study prepared by The Dow Chemical Company. 59 p.Page 47 of 68 

### APPENDIX C: Risk Estimation Methods

Risk estimation integrates the results of the exposure and ecotoxicity data to evaluate the likelihood of adverse ecological eff ects. There are generally two approaches used in assessing risks from industrial process and water systems, a risk quotient (RQ) me thod and a probabilistic method.

Risk Quotient (RQ) Method

In the RQ method, estimates of exposure are divided by ecotoxicity endpoint values. These RQs are then compared to presumptive levels of concern (LOCs) to identify potential risk to nontarget organisms and the need to consider regulatory action. These LOCs are standards used by the EPA to indicate pote ntial risk to non-target organi sms and the need to consider regulatory action; the development of these LO Cs are discussed in detail in the Agency’s Overview Document 1 . Types of RQs (e.g., acute vers us chronic), RQ equations, and corresponding LOCs and risk presum ptions are tabulated in Table 9.

Table 9. Risk Presumption Categories

Risk Presumption for Terrestrial Animals RQ LOC

Acute: Presumption of high acute risk for nontarget animals EEC A /LC 50 or EEC B /LD 50 > 0.5 Acute Restricted Use: Presumption of acute risk for nontarget animals, but potentially may be mitigated through restricted use EEC A /LC 50 or EEC B /LD 50 > 0.1
Acute Endangered Species: Endangered species may be affected acutely EEC A /LC 50 or EEC B /LD 50 > 0.05 Chronic Risk: Presumption of chronic risk to nontarget animals, endangered species may be affected chronically EEC A /NOAEC > 1.0

Risk Presumption for Aquatic Animals RQ LOC

Acute: Presumption of high acute risk for nontarget animals EEC C /LC 50 or EEC C /EC 50 or EEC C /IC 50 > 0.5

Acute Restricted Use: Presum p tion of acute ris k for nontar g et animals, EEC C /LC 50 or EEC C /EC 50 or > 0.1 Acute Endangered Species: Endangered species may be affected acutely EEC C /LC 50 or EEC C /EC 50 or C > 0.05
Chronic Risk: Presumption of chronic risk to nontarget animals, endangered species may be affected chronically Water: EEC C /NOAEC > 1.0

Sediment: EEC D /NOAEC >1.0 Risk Presumption for Aquatic Plants RQ LOC

Non-Endangered Species: Presumption of high risk to all nontarget aquatic plants EEC C /IC 50 > 1.0

Endangered Species: Endangered plants may be affected EEC C /NOAEC or EEC C /IC 05 E > 1.0 Risk Presumption for Terrestrial Plants RQ LOC Non-Endangered Species: Presumption of high risk to all nontarget
p lants EEC C /IC 25 > 1.0
Endangered Species: Presumption of high risk to all nontarget aquatic plants EEC C /NOAEC or EEC C /IC 05 E > 1.0

A Dietary exposure in parts per million (ppm) of the pesticide in/on dietary items.

1 http://www.epa.gov/espp/consultation/ecorisk-overview.pdfPage 48 of 68 B Dietary exposure dose in mg/kg-bw/day.

C Concentration in water in parts per million (ppm).

D Concentration in mg/kg-sediment.

E An IC 05 can be used in lieu of an NOAEC, if one cannot be determined or if it is above the IC 25 .
Probabilistic Method

For use patterns that result in antimicrobial s entering surface wate r by way of industrial wastewater treatment plants or direct discharge from the industri al site without treatment, the Agency relies upon estimating loadings of antimic robials to industrial wastewater treatment plants and using the General P opulation Exposures from Industria l Releases module of E-FAST to estimate number of days of exceedance of concentrations of concern (COCs) for aquatic organisms. COCs for acute effects on non-liste d aquatic vertebrates and invertebrates were determined by dividing LC 50 (or EC 50 ) values from acute toxicity te sts on aquatic vertebrates and invertebrates, respectively, by 2. COCs for chr onic effects for non-listed aquatic vertebrate and invertebrate species were base d on chronic NOAEC values from te sts on aquatic vertebrates and invertebrates, respectively. Acute COCs for liste d endangered and threatened aquatic vertebrates and invertebrates were dete rmined by dividing acute LC 50 (or EC 50 ) values from acute toxicity tests on aquatic vertebrates and invertebrates, respectively, by 20. COCs for nonlisted aquatic vascular plants and algae are based on IC 50 values. COCs for enda ngered algae and aquatic vascular plants are ba sed on NOAEC values.

Based on probabilistic modeling results, if the acute COC (one-half of theLC 50 or EC 50 ) determined for any key aquatic receptor group is exceeded for one day or more based on results from the high-end scenario (i.e., the 10 th percentile of the ratio of stream flows to plant flows), then potential acute risks to such receptor gr oups are indicated. In a ddition, if the endangered COC (one-twentieth of the LC 50 or EC 50 ) determined for any key aquatic receptor group is exceeded for one day or more based on results fro m the high-end scenario, then potential acute risks to endangered aquatic organisms in such rece ptor groups are indicated. Furthermore, if the chronic COC (NOAEC or NOAEL) for any key aquatic recepto r group is exceeded for 20 days or more based on results from the high-end scen ario, then potential chronic risks for such receptor groups are indicated.Page 49 of 68 

### APPENDIX D: Estimation of Potential Risks from Exposure of Aquatic Organisms
to DTEA Downstream of Recirculating Cooling Towers

This appendix is divided into two sections. The first section is a complete listing of the tabulated results of the modeling runs. The second sect ion is a discussion of the methodology and step wise approach for the Exposure and Fate Assessment Screening Tool (E-FAST) .



### Section 1: Estimates of Exposures and Risks to Freshwater Organisms based on Maintenance Treatment Scenarios

Table 10 presents estimates of numbers of days per year of exceedance of concentrations of concern for aquatic organisms downstream of la rge-size cooling towers based on a high-end scenario and application rates for maintenance treatment proposed on the product label. These estimates assume no treatment of blowdown wa ter, hence no removal of DTEA prior to discharge to surface water.

Table 10 High-End Scenario Estimates of Number of Days per Year of Exceedance of COCs for Aquatic Organisms Downstream of Large-Size Cooling Towers based on Facilities Belonging to the St eam Electric Power Plants SIC Code – Assumes No Treatment (No Removal)

Environmental Release (kg/site/day) DTEAConcentration (ppm ae) Acute Freshwater Fish (COC = 110 ppb) Endangered Freshwater Fish (COC = 11 ppb) Chronic Freshwater Fish (COC = 36.5 ppb) Acute Freshwater

Invertebrate (COC = 17 ppb) EndangeredFreshwaterInvertebrate (COC = 1.7 ppb) Chronic Freshwater

Invertebrate (COC = 7.8 ppb) Aquatic Plants (COC = 10 ppb)

Number of Days per Year of Exceedance of COCs out of 360 Days Release 84 24.4 352 360 359 360 360 360 360 20.4 5.9 302 359 180 356 360 301 359 6.7 1.95 218 348 302 337 360 353 350 1.7 0.5 110 291 195 258 355 312 297

Table 11 presents estimates of numbers of da ys per year of exceedance of concentrations of concern for aquatic organisms downstream ofmoderate-size cooling towers based on a highend scenario and application ra tes for maintenance treatment proposed on the product label. These estimates assume no treatm ent of blowdown water, hence no removal of DTEA prior to discharge to surface water.Page 50 of 68 Table 11 High-End Scenario Estimates of Number of Days per Year of Exceedance of COCs for Aquatic Organisms Downstream of Moderate-Size Cooling Towers based on Facilities Belonging to the St eam Electric Power Plants SIC Code – Assumes no treatment and no removal

Environmental Release (kg/site/day) DTEAConcentration (ppm ae) Acute Freshwater Fish (COC = 110 ppb) Endangered Freshwater Fish (COC = 11 ppb) Chronic Freshwater Fish (COC = 36.5 ppb) Acute Freshwater

Invertebrate (COC = 17 ppb) EndangeredFreshwaterInvertebrate (COC = 1.7 ppb) Chronic Freshwater

Invertebrate (COC = 7.8 ppb) Aquatic Plants (COC = 10 ppb)

Number of Days per Year of Exceedance of COCs out of 360 Days Release 1.7 24.4 11 87 33 64 229 109 93 0.41 5.9 3 27 8 17 116 37 29 0.13 1.95 1 9 3 6 51 12 10 0.03 0.5 0 3 1 2 15 4 3

Table 12 presents estimates of numbers of da ys per year of exceedance of concentrations of concern for aquatic organisms downstream of large-size cooling towers based on an average case scenario and application ra tes for maintenance treatment proposed on the product label. These estimates assume no treatm ent of blowdown water, hence no removal of DTEA prior to discharge to surface water.

Table 12 Average Case Scenario Estimates of Number of Days per Year of Exceedance of COCs for Aquatic Organisms Downstream of Large-Size Cooling Towers based on Facilities Belonging to the St eam Electric Power Plants SIC Code – Assumes No Treatment and No Removal

Environmental Release (kg/site/day) DTEAConcentration (ppm ae) Acute Freshwater Fish (COC = 110 ppb) Endangered Freshwater Fish (COC = 11 ppb) Chronic Freshwater Fish (COC = 36.5 ppb) Acute Freshwater

Invertebrate (COC = 17 ppb) EndangeredFreshwaterInvertebrate (COC = 1.7 ppb) Chronic Freshwater

Invertebrate (COC = 7.8 ppb) Aquatic Plants (COC = 10 ppb)

Number of Days per Year of Exceedance of COCs out of 360 Days Release 84 24.4 89 211 143 187 293 228 216 20.4 5.9 46 131 77 109 233 151 137 6.7 1.95 26 80 46 66 174 94 84 1.7 0.5 11 42 22 34 100 50 44

Table 13 presents estimates of numbers of da ys per year of exceedance of concentrations of concern for aquatic organisms downstream of moderate-size cooling towers based on an average case scenario and applic ation rates for maintenance treatment proposed on the product label. These estimates assume no treatment of blowdown water, hence no removal of DTEA prior to discharge to surface water.Page 51 of 68 Table 13 Average Case Scenario Estimates of Number of Days per Year of Exceedance of COCs for Aquatic Organisms Downstream of Moderate-Size Cooling Towers based on Facilities Belonging to the St eam Electric Power Plants SIC Code – Assumes No Treatment and No Removal

Environmental Release (kg/site/day) DTEAConcentration (ppm acidequivalents) Acute Freshwater Fish (COC = 110 ppb) Endangered Freshwater Fish (COC = 11 ppb) Chronic Freshwater Fish (COC = 36.5 ppb) Acute Freshwater

Invertebrate (COC = 17 ppb) EndangeredFreshwaterInvertebrate (COC = 1.7 ppb) Chronic Freshwater

Invertebrate (COC = 7.8 ppb) Aquatic Plants (COC = 10 ppb)

Number of Days per Year of Exceedance of COCs out of 360 Days Release 1.7 24.4 11 42 22 34 100 50 44 0.41 5.9 4 20 9 15 52 24 21 0.13 1.95 1 9 4 7 30 12 10 0.03 0.5 0 3 1 2 12 4 3

Table 14 presents estimates of numbers of da ys per year of exceedance of concentrations of concern for aquatic organisms downstream of large-size cooling towers based on a high-end scenario and application rates for maintenance treatment proposed on the product label. These estimates assume 93 percent removal of DTEA du ring wastewater treatment based on activated sludge sorption isotherm data that indicate that from 93 to 98 percent of DTEA is removed during wastewater treatment vi a sorption to activated sludge.

Table 14 High-End Scenario Estimates of Number of Days per Year of Exceedance of COCs for Aquatic Organisms Downstream of Large-Size Cooling Towers based on Facilities Belonging to the Steam Electric Power Plants SIC Code – Assumes 93 percent removal during WWT

Environmental Release (kg/site/day) DTEAConcentration (ppm acidequivalents) Acute Freshwater Fish (COC = 110 ppb) Endangered Freshwater Fish (COC = 11 ppb) Chronic Freshwater Fish (COC = 36.5 ppb) Acute Freshwater

Invertebrate (COC = 17 ppb) EndangeredFreshwaterInvertebrate (COC = 1.7 ppb) Chronic Freshwater

Invertebrate (COC = 7.8 ppb) Aquatic Plants (COC = 10 ppb)

Number of Days per Year of Exceedance of COCs out of 360 Days Release 84 24.4 207 345 293 332 360 352 347 20.4 5.9 98 278 180 244 353 301 285 6.7 1.95 42 188 98 152 323 217 196 1.7 0.5 11 88 34 65 231 110 94

Table 15 presents estimates of numbers of da ys per year of exceedance of concentrations of concern for aquatic organisms downstream ofmoderate-size cooling towers based on a highend scenario and application ra tes for maintenance treatment proposed on the product label. These estimates assume 93 percent removal of DTEA during wastewat er treatment based onPage 52 of 68 activated sludge sorption isothe rm data that indicate that from 93 to 98 percent of DTEA is removed during wastewater treatmen t via sorption to activated sludge.

Table 15 High-End Scenario Estimates of Number of Days per Year of Exceedance of COCs for Aquatic Organisms Downstream of Moderate-Size Cooling Towers based on Facilities Belonging to the Steam Electric Power Plants SIC Code – Assumes 93 percent removal during WWT

Environmental Release (kg/site/day) DTEAConcentration (ppm ae) Acute Freshwater Fish (COC = 110 ppb) Endangered Freshwater Fish (COC = 11 ppb) Chronic Freshwater Fish (COC = 36.5 ppb) Acute Freshwater

Invertebrate (COC = 17 ppb) EndangeredFreshwaterInvertebrate (COC = 1.7 ppb) Chronic Freshwater

Invertebrate (COC = 7.8 ppb) Aquatic Plants (COC = 10 ppb)

Number of Days per Year of Exceedance of COCs out of 360 Days Release 1.7 24.4 11 87 33 64 229 109 93 0.41 5.9 3 27 8 17 116 37 29 0.13 1.95 1 9 3 6 51 12 10 0.03 0.5 0 3 1 2 15 4 3

Table 16 presents estimates of numbers of da ys per year of exceedance of concentrations of concern for aquatic organisms downstream of large size cooling towers based on an average case scenario and application rates proposed on the product label. These estimates assume 93 percent removal of DTEA during wastewater treatment based on activated sludge sorption isotherm data that indicate that from 93 to 98 percent of DTEA is removed during wastewater treatment via sorption to activated sludge.

Table 16 Average Case Scenario Estimates of Number of Days per Year of Exceedance of COCs for Aquatic Organisms Downstream of Large-Size Cooling Towers based on Facilities Belonging to the Steam Electric Power Plants SIC Code – Assumes 93 percent removal during WWT

Environmental Release (kg/site/day) DTEAConcentration (ppm ae) Acute Freshwater Fish (COC = 110 ppb ae) Endangered Freshwater Fish (COC =

11 ppb ae) Chronic Freshwater Fish (COC = 36.5 ppb ae) Acute Freshwater

Invertebrate (COC = 17

ppb ae) EndangeredFreshwaterInvertebrate (COC = 1.7 ppb) Chronic Freshwater

Invertebrate (COC = 7.8

ppb ae) Aquatic Plants (COC = 10 ppb ae)

Number of Days per Year of Exceedance of COCs out of 360 Days Release 84 24.4 24 76 43 62 167 88 79 20.4 5.9 10 39 20 31 93 46 41 6.7 1.95 4 21 10 16 56 26 23 1.7 0.5 1 9 3 6 28 11 10Page 53 of 68 Table 17 presents estimates of numbers of da ys per year of exceedance of concentrations of concern for aquatic organisms downstream of moderate size cooling towers based on an average case scenario and applic ation rates proposed on the pr oduct label. These estimates assume 93 percent removal of DTEA during wa stewater treatment based on activated sludge sorption isotherm data that indicate that from 93 to 98 percent of D TEA is removed during wastewater treatment via so rption to activated sludge.

Table 17 Average Case Scenario Estimates of Number of Days per Year of Exceedance of COCs for Aquatic Organisms Downstream of Moderate-Size Cooling Towers based on Facilities Belonging to the Steam Electric Power Plants SIC Code – Assumes 93 percent removal during WWT

Environmental Release (kg/site/day) DTEAConcentration (ppm acidequivalents) Acute Freshwater Fish (COC = 110 ppb) Endangered Freshwater Fish (COC = 11 ppb) Chronic Freshwater Fish (COC = 36.5 ppb) Acute FreshwaterInvertebrate (COC = 17 ppb) EndangeredFreshwaterInvertebrate (COC = 1.7 ppb) Chronic FreshwaterInvertebrate (COC = 7.8 ppb) Aquatic Plants (COC = 10 ppb)

Number of Days per Year of Exceedance of COCs out of 360 Days Release 1.7 24.4 1 9 3 6 28 11 9 0.41 5.9 0 3 1 2 12 4 3 0.13 1.95 0 1 0 1 5 1 1 0.03 0.5 0 0 0 0 1 0 0

Estimates of Exposures and Risks to Freshwater Organisms based on Scenarios for Initial
Treatment of Fouled Systems

Table 18 presents results indicating whethe r or not concentrations of concern for freshwater aquatic organisms are downstream of large-size cooling towers would or would not be expected to be exceeded for assuming one da y of application and re lease based on a high-end scenario and application rates for initial tr eatment proposed on the product label. These estimates assume no treatment of blowdown wa ter, hence no removal of DTEA prior to discharge to surface water.

For all initial application rates proposed on the product label, all COCs for aquatic organisms are predicted to be exceeded.Page 54 of 68 Table 18 High-End Scenario Estimates of Number of Days per Year of Exceedance of COCs for Aquatic Organisms Downstream of Large-Size Cooling Towers based on Facilities Belonging to the St eam Electric Power Plants SIC Code – Assumes No Treatment (No Removal)

Environmental Release (kg/site/day) DTEAConcentration (ppm ae) Acute Freshwater Fish (COC = 110 ppb) Endangered Freshwater Fish (COC = 11 ppb) Chronic Freshwater Fish (COC = 36.5 ppb) Acute Freshwater

Invertebrate (COC = 17 ppb) EndangeredFreshwaterInvertebrate (COC = 1.7 ppb) Chronic Freshwater

Invertebrate (COC = 7.8 ppb) Aquatic Plants (COC = 10 ppb)

Exceedance of COCs Based on 1 Day of Release 140 40 1 1 1 1 1 1 1 84 24.4 1 1 1 1 1 1 1 20.4 5.9 1 1 1 1 1 1 1

Table 19 presents results indicating whethe r concentrations of concern for aquatic organisms downstream of moderate -size cooling towers would or would not be expected to be exceeded assuming one day of application a nd release based on a high-end scenario and application rates for initial treat ment proposed on the product labe l. These estimates assume no treatment of blowdown water, hence no removal of DTEA prior to discharge to surface water. At 2.8 and 1.7 kg/site/day, COCs for all aquatic or ganisms except for acute freshwater fish are exceeded for one day. At 0.41 kg/site/day COCs for aquatic plants, chronic freshwater invertebrates, and endangered freshwater invertebrates are exceeded for one day.

Table 19 High-End Scenario Estimates of Number of Days per Year of Exceedance of COCs for Aquatic Organisms Downstream of Moderate-Size Cooling Towers based on Facilities Belonging to the St eam Electric Power Plants SIC Code – Assumes no treatment and no removal

Environmental Release (kg/site/day) DTEAConcentration (ppm ae) Acute Freshwater Fish (COC = 110 ppb) Endangered Freshwater Fish (COC = 11 ppb) Chronic Freshwater Fish (COC = 36.5 ppb) Acute Freshwater

Invertebrate (COC = 17 ppb) EndangeredFreshwaterInvertebrate (COC = 1.7 ppb) Chronic Freshwater

Invertebrate (COC = 7.8 ppb) Aquatic Plants (COC = 10 ppb)

Exceedance of COCs Based on 1 Day of Release 2.8 40 0 1 1 1 1 1 1 1.7 24.4 0 1 1 1 1 1 1 0.41 5.9 0 0 0 0 1 1 1

Table 20 presents results indicating whethe r concentrations of concern for aquatic organisms downstream of large-size cooling towe rs would or would not be expected to be exceeded assuming one day of application and release based on an average case scenario andPage 55 of 68 application rates for initial treat ment proposed on the product label. These estimates assume that blowdown water is discharged directly to surface water without undergoing wastewater treatment. At 2.8 and 1.7 kg/site/day, COCs for all aquatic organisms except for acute freshwater fish are exceeded for one day. At 0.41 kg/site/day, COCs for aquatic plants, chronic freshwater invertebrates, and endangered fres hwater invertebrates are exceeded for one day.

Table 20 Average Case Scenario Estimates of Number of Days per Year of Exceedance of COCs for Aquatic Organisms Downstream of Large-Size Cooling Towers based on Facilities Belonging to the St eam Electric Power Plants SIC Code – Assumes No Treatment and No Removal

Environmental Release (kg/site/day) DTEAConcentration (ppm ae) Acute Freshwater Fish (COC = 110 ppb) Endangered Freshwater Fish (COC = 11 ppb) Chronic Freshwater Fish (COC = 36.5 ppb) Acute Freshwater

Invertebrate (COC = 17 ppb) EndangeredFreshwaterInvertebrate (COC = 1.7 ppb) Chronic Freshwater

Invertebrate (COC = 7.8 ppb) Aquatic Plants (COC = 10 ppb)

Exceedance of COCs Based on 1 Day of Release 140 40 0 1 0 1 1 1 1 84 24.4 0 1 0 1 1 1 1 20.4 5.9 0 0 0 0 1 0 0

Table 21 presents results indicating whethe r concentrations of concern for aquatic organisms downstream of moderate -size cooling towers would or would not be expected to be exceeded assuming one day of application and release based on an average case scenario and application rates for initial treat ment proposed on the product label. These estimates assume that blowdown water is discharged directly to surface water without undergoing wastewater treatment. No COCs examined would be expected to be exceeded for the one-day of release.

Table 21 Average Case Scenario Estimates of Number of Days per Year of Exceedance of COCs for Aquatic Organisms Downstream of Moderate-Size Cooling Towers based on Facilities Belonging to the St eam Electric Power Plants SIC Code – Assumes No Treatment and No Removal

Environmental Release (kg/site/day) DTEAConcentration (ppm acidequivalents) Acute Freshwater Fish (COC = 110 ppb) Endangered Freshwater Fish (COC = 11 ppb) Chronic Freshwater Fish (COC = 36.5 ppb) Acute Freshwater

Invertebrate (COC = 17 ppb) EndangeredFreshwaterInvertebrate (COC = 1.7 ppb) Chronic Freshwater

Invertebrate (COC = 7.8 ppb) Aquatic Plants (COC = 10 ppb)

Exceedance of COCs Based on 1 Day of Release 2.8 40 0 0 0 0 0 0 0 1.7 24.4 0 0 0 0 0 0 0 0.41 5.9 0 0 0 0 0 0 0Page 56 of 68 Table 22 presents results indicating whethe r concentrations of concern for aquatic organisms downstream of large-size cooling towe rs would or would not be expected to be exceeded assuming one day of application a nd release based on a high-end scenario and application rates for initial treat ment proposed on the product labe l. These estimates assume 93 percent removal of DTEA during wastewater treatment based on activated sludge sorption isotherm data that indicate that from 93 to 98 percent of DTEA is removed during wastewater treatment via sorption to activat ed sludge. For all environmenta l releases examined, COCs are exceeded for one day with the exception of the COC for acute freshwater fish for an environmental release of 20.4 kg/site/day (5.9 ppm).

Table 22 High-End Scenario Estimates of Number of Days per Year of Exceedance of COCs for Aquatic Organisms Downstream of Large-Size Cooling Towers based on Facilities Belonging to the Steam Electric Power Plants SIC Code – Assumes 93 percent removal during WWT

Environmental Release (kg/site/day) DTEAConcentration (ppm acidequivalents) Acute Freshwater Fish (COC = 110 ppb) Endangered Freshwater Fish (COC = 11 ppb) Chronic Freshwater Fish (COC = 36.5 ppb) Acute Freshwater

Invertebrate (COC = 17 ppb) EndangeredFreshwaterInvertebrate (COC = 1.7 ppb) Chronic Freshwater

Invertebrate (COC = 7.8 ppb) Aquatic Plants (COC = 10 ppb)

Exceedance of COCs Based on 1 Day of Release 140 40 1 1 1 1 1 1 1 84 24.4 1 1 1 1 1 1 1 20.4 5.9 0 1 1 1 1 1 1

Table 23 presents results indicating whethe r concentrations of concern for aquatic organisms downstream of moderate -size cooling towers would or would not be expected to be exceeded assuming one day of application a nd release based on a high-end scenario and application rates for initial treat ment proposed on the product labe l. These estimates assume 93 percent removal of DTEA during wastewater treatment based on activated sludge sorption isotherm data that indicate that from 93 to 98 percent of DTEA is removed during wastewater treatment via sorption to activated sludge. Only the COC for endangered freshwater invertebrates would be exceeded for one day of release at environmental releases of 2.8 kg/site/day (40 ppm) and 1.7 kg/site per day (24.4 ppm).Page 57 of 68 Table 23 High-End Scenario Estimates of Number of Days per Year of Exceedance of COCs for Aquatic Organisms Downstream of Moderate-Size Cooling Towers based on Facilities Belonging to the Steam Electric Power Plants SIC Code – Assumes 93 percent removal during WWT

Environmental Release (kg/site/day) DTEAConcentration (ppm acidequivalents) Acute Freshwater Fish (COC = 110 ppb) Endangered Freshwater Fish (COC = 11 ppb) Chronic Freshwater Fish (COC = 36.5 ppb) Acute Freshwater

Invertebrate (COC = 17 ppb) EndangeredFreshwaterInvertebrate (COC = 1.7 ppb) Chronic Freshwater

Invertebrate (COC = 7.8 ppb) Aquatic Plants (COC = 10 ppb)

Exceedance of COCs Based on 1 Day of Release 2.8 40 0 0 0 0 1 0 0 1.7 24.4 0 0 0 0 1 0 0 0.41 5.9 0 0 0 0 0 0 0

Table 24 presents results indicating whethe r concentrations of concern for aquatic organisms downstream of large-size cooling towe rs would or would not be expected to be exceeded assuming one day of application and release based on an average case scenario and application rates for initial treat ment proposed on the product labe l. These estimates assume 93 percent removal of DTEA during wastewater treatment based on activated sludge sorption isotherm data that indicate that from 93 to 98 percent of DTEA is removed during wastewater treatment via sorption to activated sludge. Only the COC for endangered freshwater invertebrates would be exceeded for one day of release at an environmental release of 140kg/site/day (40 ppm).

Table 24 Average Case Scenario Estimates of Number of Days per Year of Exceedance of COCs for Aquatic Organisms Downstream of Large-Size Cooling Towers based on Facilities Belonging to the Steam Electric Power Plants SIC Code – Assumes 93 percent removal during WWT

Environmental Release (kg/site/day) DTEAConcentration (ppm acidequivalents) Acute Freshwater Fish (COC = 110 ppb) Endangered Freshwater Fish (COC = 11 ppb) Chronic Freshwater Fish (COC = 36.5 ppb) Acute Freshwater

Invertebrate (COC = 17 ppb) EndangeredFreshwaterInvertebrate (COC = 1.7 ppb) Chronic Freshwater

Invertebrate (COC = 7.8 ppb) Aquatic Plants (COC = 10 ppb)

Exceedance of COCs Based on 1 Day of Release 140 40 0 0 0 0 0 0 0 84 24.4 0 0 0 0 0 0 0 20.4 5.9 0 0 0 0 0 0 0

Table 25 presents results indicating whethe r concentrations of concern for aquatic organisms downstream of large-size cooling towe rs would or would not be expected to bePage 58 of 68 exceeded assuming one day of application and release based on an average case scenario and application rates for initial treat ment proposed on the product labe l. These estimates assume 93 percent removal of DTEA during wastewater treatment based on activated sludge sorption isotherm data that indicate that from 93 to 98 percent of DTEA is removed during wastewater treatment via sorption to activated sludge. No COCs for any aquatic organisms are exceeded at any of the environmental releases considered.

Table 25 Average Case Scenario Estimates of Number of Days per Year of Exceedance of COCs for Aquatic Organisms Downstream of Moderate-Size Cooling Towers based on Facilities Belonging to the Steam Electric Power Plants SIC Code – Assumes 93 percent removal during WWT

Environmental Release (kg/site/day) DTEAConcentration (ppm acidequivalents) Acute Freshwater Fish (COC = 110 ppb) Endangered Freshwater Fish (COC = 11 ppb) Chronic Freshwater Fish (COC = 36.5 ppb) Acute Freshwater

Invertebrate (COC = 17 ppb) EndangeredFreshwaterInvertebrate (COC = 1.7 ppb) Chronic Freshwater

Invertebrate (COC = 7.8 ppb) Aquatic Plants (COC = 10 ppb)

Exceedance of COCs Based on 1 Day of Release 2.8 40 0 0 0 0 0 0 0 1.7 24.4 0 0 0 0 0 0 0 0.41 5.9 0 0 0 0 0 0 0



### Section 2: GENERAL METHODOLOGY

The General Population and Ecological Expos ure from Industrial Releases module of EFAST (Exposure and Fate Assessment Screening T ool) was used to estimate potential risks from exposure of aquatic organisms to DTEA downstream of recirculating coo ling towers. Key input parameters required to run th is module of E-FAST include:

 Environmental release of DTEA to surface water (kg/site/day);

 Concentrations of concern (COC ) for aquatic organisms (ug/L);

 Standard Industrial Classification (SIC) code(s) selected to represent recirculating cooling tower facilities;

 Wastewater treatment removal of DTEA (percent);

 Annual number of days of release to surface water (days per year); and

 Selection of high-end or average case scenario.

A discussion of the basis of high-end and average case scenario results is included at the end of this Appendix. The approach used to estimate aquatic exposures to DTEA from release of blowdown water from recircula ting cooling towers can be de scribed in four steps:

Page 59 of 68  Step 1: Estimate environmental release to surface water from recirculating cooling tower blowdown water from recirculating cooling tower blowdown water (kg/site/day);

 Step 2: Determine percent removal during wastewater treatment;

 Step 3: Derive concentrations of c oncern (COC) for aquatic organisms from LC 50 and NOAEC values; and

 Step 4: Estimate aquatic exposures from releases of recirculating cooling tower blowdown water to surface water using the general population exposures from industrial releases module of E-FAST.

STEP 1: Estimate Environmental Release to Surface Water from Recirculating Cooling Tower Blowdown Water (B) in kilograms per site per day

A generic scenario developed by OPPT/C EB (Office of Pollution Prevention and Toxics/Chemical Engineering Branch) for recirc ulating cooling towers (USEPA, undated) was used to estimate daily releases to surface wate r of DTEA in blowdown water in kilograms per site per day.

The following equation is used to estimate rel eases of antimicrobial pesticide to surface water from blowdown:

B = (0.6%) (X R ) (R) (5760 x 10 -06 min-kg/day-gal)

where:

B = release of antimicrobial pesticide via bl owdown water to surface water (kg/site/day);

X R = concentration of antimic robial pesticide in recirc ulating water (ppm); and

R = recirculation rate of coo ling water (gallons per minute).

The conversion factor, 5760 x 10 -06 min-kg/day-gal is derived from:

(1440 min/day) (4 kg/gal) (10 -06 ppm) in which the blowdown water is assumed to have a specific gravity of 1.0, thus 1 liter weighs 1 kilogram, and the conversion of 3.78 liters per gallon is expressed in kilograms per gallon and rounded up to the nearest significan t figure. The value, 0.6% is the percentage of cooling tower water that is assumed to be released to surface water via blowdown.

The following input values were used in this calculation:

 X R : concentration of DTEA in recirculating c ooling tower water – 0.5 to 40 ppm DTEA acid equivalents (derived from information on the label for “Antimicrobial DTEA 15%” (EPA Reg. No. 464-619) based on the range of product application rates (0.5 to 41 fluid ounces per 1000 gallons of water) adjusted for product de nsity (8.5 pounds per gallon) and expressed as DTEA acid equivalents (12.8%)Page 60 of 68  R:recirculation rate of co oling water– 2000 gallons per minute for a moderate-size cooling tower (default value based on st andard scenario de veloped by OPPT/CEB)) and 100,000 gallons per minute for a large-si ze cooling tower (default value based on standard scenario developed by OPPT/CEB).

The table that follows presents values of environmental releases of DTEA modeled for large-size and moderate-size cooling towers ac cording to product application rate, product density, and DTEA concentra tion in acid equivalents.

Product Application rate per 1000 gallons of water Application rate adjusted for product density of 8.5 pounds per gallon DTEA Concentration (ppm

acid equivalents) Environmental Release: Large-Size Cooling Tower

(kg/site/day) Environmental Release: Moderate-Size Cooling Tower

(kg/site/day) 41 fluid ounces 41.8 fluid ounces 40 140 2.8 25 fluid ounces 25.5 fluid ounces 24.4 84 1.7 6 fluid ounces 6.1 fluid ounces 5.9 20.4 0.41 2 fluid ounces 2.0 fluid ounces 1.95 6.7 0.13 0.5 fluid ounces 0.5 fluid ounces 0.5 1.7 0.03

STEP 2: Determine Percent Removal During Wastewater Treatment

Data from an activated sludge sorption is otherm test (OCSPP Guideline 835.1110) that were submitted to the Agency for review indi cate that from 93.2-98.5 percent of DTEA is removed via its sorption to act ivated sludge (MRID 49004201). For the purpose of this exposure and risk assessment, it was assumed that removal during wastewater treatm ent would result from sorption to activated sludge and that 93 per cent DTEA would be rem oved during wastewater

treatment.
There is no information on the product labe l to indicate that bl owdown water must be treated prior to discharge to surface water. Consequently, exposures and risks to aquatic organisms were also estimated assuming that bl owdown water could be di scharged directly to surface water without treatment. In this case, it was assumed that there would be no removal of DTEA from blowdown wate r prior to its discharg e to surface water.

STEP 3: Estimate Concentrations of Concern (COC) for Aquatic Organisms

The results of the DtD module are expressed as number of days of exceedance of COCs for aquatic organisms. The Agency uses the most sensitive ecotoxicology endpoints for surrogate species to assess risk to each aqua tic receptor group, such as freshwater fish, freshwater invertebrate, sediment-dwelling invert ebrate, and aquatic plants. COCs for acute effects were determined by dividing LC 50 values from acute toxicity tests on aquatic vertebrates and invertebrates by 2. COCs for chronic eff ects for non-listed species were based on No Observed Adverse Effects Concentration (NOAEC) values from tests on aquatic vertebrates andPage 61 of 68 invertebrates. COCs for listed endangered and threatened aquatic organisms were determined by dividing LC 50 values from acute toxic ity tests on aquatic vertebra tes and invertebrates by 20. Acute COCs for aquatic vascular plants and algae are based on EC 50 values. COCs for endangered algae and aquatic vascular plants are based on NOAEC values.

STEP 4: Estimate General Population and Ecological Exposure from Industrial Releases

E-FAST, version 2.0, was used to determine the magnitude and fre quency of exposure of aquatic organisms from releas es of DTEA via blowdown wate r from recirculating cooling towers. For detailed information on the featur es, data, and methods on which the models in EFAST, version 2.0, are based, refer to the latest version of the Docume ntation Manual for EFAST, version 2.0 (USEPA 2007). This discussion is limited to summarizing the steps required to estimate exposure of aquatic organisms to blowdown water from industrial use of DTEA in recirculating cooling towers using the Gene ral Population and Ecological Exposure from Industrial Releases module of E-FAST with th e PDM (probabilistic dilu tion model) option. The user is guided through a series of menus or page s that provide prompts indicating where the user should input data. Key input parameters need ed to run this module and option include:

 Environmental release to surface water in kg/site/day (estimated from Step 1);

 Percent removal of DTEA during wastew ater treatment (from Step 2); and

 Concentrations of Concern (COC) for aqua tic organisms (estimated from Step 3).

One of the first screens that appears when running the General Population and Ecological Exposure from Industrial Releases module of E-FA ST is the physical/chemical and fate inputs screen; Upon accessing this screen, the user must enter the following information:

 Chemical identificati on (e.g., CAS number);

 Chemical name or abbreviation;

 Bioconcentration factor (measured or estima ted) (used to estimate human exposure from ingestion of fish);

 Percent wastewater treatment re moval (measured or estimated);

 Percent adsorption to wastew ater treatment sludge (measured or estimated); and

 Percent drinking water treatment removal (in the absence of data, assume no removal).

The user must also select the appropriat e models for estimating exposure to aquatic organisms. (In this instance, the appropria te model to use is th e general population and ecological exposure from industrial releases to surface water model with the option to also run the probabilistic dilution model.) Next, the user accesses the “Release Information Page”. This page consists of thr ee sub-pages including:

 general release information;

 select a facility; andPage 62 of 68  select an SIC code.

The “select a facility” subpage, which accesses a database of site-specific information for manufacturing facilities, is not applicable for estimating exposures from processing and industrial use. To estimate exposures to aqua tic organisms from surface water releases from processing or industrial use, th e user must provide input valu es for the “general release information” subpage and the “select an SI C code” subpage. On the general releases information subpage, the user must input the following:

 type (media) of release (i.e., surface water, landfill, and/or ambient air); in this case, the user would select “surface water”.

 amount of release in kg/site /day, based on the results from CEB’s generic scenario (from Step 1 of this appendix) ;

 days per year of release, based on results from CEB’s generic scenario; the default value for the recirculating coo ling towers scenario is 360.

 Upon being present with a choice of selec ting “SIC code anal ysis” or “facility analysis”, select SIC code analysis. A me nu of SIC code descrip tions will appear on the screen and the user will be prompted to select one; in this instance, the appropriate SIC code description would be “Steam Electric Power Plants”.

 Input the number of cooling tower site s; since there is no production volume information available for DTEA used in reci rculating cooling towers that can be used to derive this input, no value is entered.

 In the box, “enter release activity ”, the user has the option to enter a description of the release; in this case, an apt description might be “indirect rele ase of cooling tower blowdown”.

 Place a check in the box, “include PDM run”.

 Enter three values for concentrations of concern.

 Select results for high en d or average exposure.

 Finally, check the box, “Release activities co mpleted? Continue to Exposure Factors page.” Upon checking this box, the Exposure Factors page will appear.

The information in the exposure factors page is not used to estimate exposures to aquatic organisms, but is used to quantify human exposur es from ingestion of drinking water and fish. This page includes default values for body wei ght, exposure duration, averaging time, and acute and chronic drinking water and fi sh ingestion rates. These valu es are automatically selected unless the user changes them.

DESCRIPTION OF HIGH

‐ END VERSUS AVERAGE CASE SCENARIO

The General Population and Ecological Expos ure from Industrial Releases module of EFAST uses environmental releases estimated in Step 1 of this Appendix, stream dilution factors (i.e., the ratio of stream flow to industrial wastewater treatmen t plant flows), and wastewater treatment removal efficiency to provide both hi gh-end and median time-averaged surface waterPage 63 of 68 concentrations of a chemical substance immediat ely downstream of a discharge point. Stream flows are not single point estimates since streams have a highly variable seasonal flow pattern. PDM uses probability distributions as inputs and calculates the resulting probability distribution of the stream concentration.

To determine stream dilution factors for indus trial uses of chemical substances such as DTEA used in recirculating cooling towers, a re presentative SIC code mu st be selected. The model will develop a distribution of stream diluti on factors based on the ratio of stream flows to plant flows for facilities that belong to a specifi ed SIC code. The distribution of stream flow values used are those immediately downstream of the facilities that belong to a specified SIC code. Stream dilution factors (SDFs) for recircul ating cooling towers were based on the ratio of receiving stream flows to facility effluent flows for those facilities included in the steam electric power plants SIC code. For the high-end scenari o, results of the number of days per year that COCs are exceeded is based on the upper 10 th percentile of SDFs. For the average case scenario, results of the number of days per year th at COCs are exceeded is based on the 50 th percentile of SDFs. For the upper 10 th percentile SDFs, or high-end scenar io, the stream flow to plant flow ratio is relatively low since this part of the st ream flow distribution repr esents the lower stream flows; consequently, plant flows can contribute considerable volum e to the flow of the stream and resulting surface water concentrati ons can be relatively high. For the 50 th %ile SDF, the stream flow to plant flow ratio is more typical.

CONVERSION OF APPLICATION RATES FROM OUNCES PER THOUSAND GALLONS TO PPM

DTEA expressed in units of ppm acid equivalents is one of the input valu es that is used to determine the loading of DTEA in kilograms per site per day. This loading is used as an input to the General Population and Ecological Exposure to Industrial Releases module of E-FAST. DTEA expressed in units of ppm acid equiva lents can be determined from the product application rates proposed on th e product label for “Antimicr obial DTEA 15%. In deriving DTEA in units of ppm acid equivalents, one must adjust for the product density and for the percent of DTEA acid equivalents (ae) in the product. The density of the product is 8.5 lbs/gallon and the percent of DTEA acid equivalents in the product is 12.8%.

An example of the steps used to convert ap plication rates proposed on the label for the product, “Antimicrobial DTEA 15%”, to DTEA in ppm acid equivalents is presented for the proposed application rate on the product label of 6 fluid ounces of product per thousand gallons of water.

STEP 1 – Use information on product density to account for the difference of the density of the product relative to the density of water. The density of product is 8.5 pounds per gallon and the density of water is 8.34 pounds per gallon.

6 fluid ounces of product x (8.5 lb/8.34 lb) = 6.11508 ounces productPage 64 of 68 STEP 2 – Determine the number of ounces of product per gallon of water.

6.11508 ounces product / 1000 gallons water = 0.00611508 ounces product per gallon of water

STEP 3 - Determine ounces of DTEA acid equivalents per gallon of water.

0.00611508 ounces product per gallon water x 0.128 DTEA = 0.0007827 ounces DTEA

STEP 4 – Convert ounces of DTEA ae per gallon of water to gr ams DTEA ae per gallon of

water.
0.0007827 ounces DTEA ae per gallon water x 28.3495 grams per ounce = 0.02219 grams DTEA ae per gallon water

STEP 5 – Convert grams of DTEA ae pe r gallon of water to grams of DTEA as per liter of water.

0.02219 grams DTEA ae per gallon of water x (1 gallon water / 3.785411 liters) = 0.005862 grams DTEA ae per liter of water

STEP 6 – Convert grams of DTEA ae pe r liter of water to mg of DT EA ae per liter of water.

0.005862 g DTEA ae per liter of water x 1000 mg/g = 5.861981 mg DTEA ae per liter of water

Since mg/L = ppm, with rounding the concen tration of DTEA ae in ppm is 5.9 ppm.



### REFERENCES

USEPA. 2007. Exposure and Fate Assessment Screening Tool (E-FAST). Version 2.0. Documentation Manual. http://www.epa.gov/opptintr/exposure/pubs/efastdl.htm

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USEPA. Undated. Generic Scenario for Reci rculating Water-Cooling Tower. Office of Polllution Prevention and Toxics, Chemical Engineering Branch (OPPT, CEB).Page 65 of 68 

### APPENDIX E: Estimated Sediment Exposure Concentrations

Screening estimates of local sediment con centrations may be obtained by multiplying the concentration of dissolved DTEA in the disc harge water by the organic carbon to sediment partition coefficient (Koc) and th e fraction of organic carbon in the sediment as follows:

C

s = K oc x f oc x C w ;

where

C

s is the concentration in bulk sedi ment in units of mg/kg-sediment;

Koc is the ratio of the concentrati on associated with sediment oc to bulk sediment concentration (mg/kg-oc per mg/kg-sediment);

f

oc is the fraction of organic carbon presen t in sediment in kg-oc/kg-sediment; and

C

w is the DTEA concentration in water in units of mg/L solution.

The estimated sediment Koc is 9,810 (L/kg) whereas the measured Koc for activated sludge is 21,566 (L/kg). Because the oc in sediments around a WWTP discharge are likely to predominately contain oc reflec tive of the WWTP process rather than natural sediment oc, sediments in these locations may have a higher so rption rate than predicted from the laboratory studies using natural sediments. Estimated expos ure concentrations in local sediments for highend conditions, under wastewater treatment and no wastewater treatment conditions using the natural sediment K oc and activated sludge K oc values (which assumes local sediment is predominated by WWTP oc output) are provided in Table 4. An additional analysis based on the 10% 30Q5, which is more reflective of everyda y inputs using the activ ated sludge Koc was included in the table, as was an analysis of th e potential for sorbed oc from a WWTP which was exposed to higher concentrations in influent to contribute to se diment exposure. Estimates for medium-size facilities, at the lowest maintena nce rate of 0.03 kg/site/day was also included.Page 66 of 68 

### APPENDIX F: Estimated Exposure Concentrations in Aquatic Biota

There were no fish or shell fish bioconcentration studies submitted to the Agency or found in the open literature fo r DTEA. EPI Suite (version 4.1 1), which includes the BCFBAF Program (version 3.01), was used to estimate bi oconcentration and bioaccumulation factors (BCF and BAF, respectively) for DTEA. Resu lts of the BCFBAF Program run are provided in Table 26. The inputs to EPI Suite included the measured log Kow of 3.72, water solubility of 0.0035 g/100 g, and the SMILES code for DTEA.

The highest estimated BAF, estimated us ing the Arnot-Gobas BCF & BAF Methods with an assumption of no biotransformation, was 3.0 (rounded) for the upper tr ophic level. Assuming biotransformation the BAF for the upper tr ophic level was estim ated as 2.4 (rounded).

Estimates of the residues in aquatic orga nisms may be obtained by multiplying the BAF by the concentration of DTEA in the water as follows:

C

diet = BAF x C w ;

where

C

diet = concentration or residue in aquatic organism in units of mg/kg-tissue wet-weight (ww);

BAF is the ratio of the concentration of a chemical in the aquatic organism (due to exposure to water and diet) to the concentration in water in units of mg/kg-tissue wet-weight to mg/L solution; and

C

w is the DTEA concentration in wa ter in units of mg/L solution.

Cooling Tower Maintenance Use with Was tewater Treatment Prior to Discharge

Setting the water concentr ation to the high end (10 th percentile 7Q10) estimated dissolved water concentration of 0.569 mg DTEA/L (Appendi x C) and using the upper trophic level log BAF estimate of 2.967 (assumption of no biotransforma tion) results in an estimated residue level of 527 mg DTEA/kg-tissue ww. Assuming biotransformation occurs, the upper trophic level log BAF estimate of 2.379 results in an estimated re sidue level of 136 mg/kg-tissue ww. At the lowest label application rate for maintenan ce the estimated 10% 7Q10 is 0.0002 mg/L for a medium-size facility. The tissue residue le vels for this case are 0.185 mg/kg-tissue ww and 0.048 mg/kg-tissue ww.

Cooling Tower Maintenance Use with No Wastewater Treatment Prior to Discharge

Setting the water concentr ation to the high end (10 th percentile 7Q10) estimated dissolved water concentration of 8.132 mg DTEA/L (Appendi x C) and using the upper trophic level log BAF estimate of 2.967 (assumption of no biotransforma tion) results in an estimated residue levelPage 67 of 68 of 7,537 mg DTEA/kg-tissue ww. Assuming biotra nsformation occurs, the upper trophic level log BAF estimate of 2.379 results in an es timated residue level of 1,946 mg/kg-tissue ww.

Table 26 BCFBAF Program (v3.01) Results from EPI Suite (v4.11)

BCFBAF Program (v3.01) Results:

============================== SMILES : CCCCCCCCCCSCCN CHEM : MOL FOR: C12 H27 N1 S1 MOL WT : 217.42 --------------------------------- BCFBAF v3.01 -------------------------------- Summary Results: Log BCF (regression-based estimate): 2.12 (BCF = 132 L/kg wet-wt) Biotransformation Half-Life (days) : 1 (normalized to 10 g fish) Log BAF (Arnot-Gobas upper trophic): 2.38 (BAF = 239 L/kg wet-wt)

Log Kow (experimental): not available from database Log Kow used by BCF estimates: 3.72 (user entered)

Equation Used to Make BCF estimate: Log BCF = 0.6598 log Kow - 0.333 + Correction

Correction(s): Value No Applicable Correction Factors

Estimated Log BCF = 2.121 (BCF = 132.3 L/kg wet-wt)

=========================================================== Whole Body Primary Biotransformation Rate Estimate for Fish:

===========================================================
------+-----+--------------------------------------------+---------+--------- TYPE | NUM | LOG BIOTRANSFORMATION FRAGMENT DESCRIPTION | COEFF | VALUE

------+-----+--------------------------------------------+---------+--------- Frag | 1 | Linear C4 terminal chain [CCC-CH3] | 0.0341 | 0.0341 Frag | 1 | Aliphatic amine [-NH2 or -NH-] | 0.4067 | 0.4067 Frag | 1 | Methyl [-CH3] | 0.2451 | 0.2451 Frag | 11 | -CH2- [linear] | 0.0242 | 0.2661 L Kow| * | Log Kow = 3.72 (user-entered ) | 0.3073 | 1.1433 MolWt| * | Molecular Weight Parameter | | -0.5575 Const| * | Equation Constant | | -1.5371

============+============================================+=========+========= RESULT | LOG Bio Half-Life (days) | | 0.0007 RESULT | Bio Half-Life (days) | | 1.002 NOTE | Bio Half-Life Normalized to 10 g fish at 15 deg C |

============+============================================+=========+=========

Biotransformation Rate Constant: kM (Rate Constant): 0.692 /day (10 gram fish) kM (Rate Constant): 0.3891 /day (100 gram fish) kM (Rate Constant): 0.2188 /day (1 kg fish) kM (Rate Constant): 0.123 /day (10 kg fish)

Arnot-Gobas BCF & BAF Methods (including biotransformation rate estimates): Estimated Log BCF (upper trophic) = 2.379 (BCF = 239.3 L/kg wet-wt) Estimated Log BAF (upper trophic) = 2.379 (BAF = 239.4 L/kg wet-wt) Estimated Log BCF (mid trophic) = 2.345 (BCF = 221.4 L/kg wet-wt) Estimated Log BAF (mid trophic) = 2.347 (BAF = 222.2 L/kg wet-wt) Estimated Log BCF (lower trophic) = 2.323 (BCF = 210.3 L/kg wet-wt) Estimated Log BAF (lower trophic) = 2.329 (BAF = 213.5 L/kg wet-wt)

Arnot-Gobas BCF & BAF Methods (assuming a biotransformation rate of zero):Page 68 of 68 Estimated Log BCF (upper trophic) = 2.742 (BCF = 552.1 L/kg wet-wt) Estimated Log BAF (upper trophic) = 2.967 (BAF = 926.6 L/kg wet-wt)