Docket Number; EPA–HQ–OPP–2010-0004 www.regulations.gov

United States Chemi cal Safety August 2010

Environmental Protection and Pollution Prevention Agency (7510P)



# 1-(3-chloroallyl)-3,5,7-triaza-1-azoniaadamantane (CTAC) Final Work Plan Registration Review August 2010Docket Number; EP A

- HQ

- OPP

- 20 1 0

- 0004 www.regulations.gov



## Docket Number: EPA-HQ-OPP-2010-0004



## 1-(3-chloroallyl)-3,5,7-triaza-l-azoniaadamantane (CTAC) Final Work Plan Registration Review Case 3069

Approved By:

# I!**Mn ~~** 

Irector, AntImIcrobials DIVIsIon

Date:

2Docket Number; EPA-HQ-OPP-2010-0004 www.regulations.gov

3 

### TABLE OF CONTENTS

1-(3-chloroallyl)-3,5,7-triaza-1-azoniaadamant ane (CTAC) Registration Review Team....................... 4

I. INTRODUCTION................................................................................................................ ..................... 5

II. COMMENTS RECEIVED ON THE PRELIMINARY WORK PLAN............................................. 6

III. RISK ASSESSMENT AND DATA NEEDS ........................................................................................ 8

IV. TIMELINE ................................................................................................................... ........................ 14

V. GLOSSARY of TERMS & ABBREVIATIONS ................................................................................. 15Docket Number; EPA-HQ-OPP-2010-0004 www.regulations.gov

1-(3-chloroallyl)-3,5,7-triaza- 1-azoniaadamantane (CTAC ) Registration Review

Team

Human Health & Environmental Effects Timothy Dole

Srinivas Gowda

Risk Management Rebecca von dem Hagen

Lance Wormell

Office of General Counsel Philip Ross

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I. INTRODUCTION

This is the E nvironmental Protection Agency’s (EPA or “the Agency”) Final Work Plan (FWP) for the registration re view of 1-(3-chlor oallyl)-3,5,7-triaza-1- azoniaadamantane (CTAC). The work plan includes the expected registration review timeline. The work plan also addresse s public comments received concerning the Preliminary Work Plan (PWP) in the Su mmary Document which was posted in the CTAC registration review docket, and any other comments concerni ng the initial docket postings. The Summary Document provided information on what EPA knows about the pesticide and what additional risk analyses a nd data or information the Agency believes are needed to make a regist ration review decision.

The Agency is implementing the registration review program pursuant to Section 3(g) of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and will review each registered pesticide every 15 years to de termine whether it continues to meet the FIFRA standard for registration. Changes in science, public policy and pesticide use practices will occur over time. The registra tion review program is intended to make sure that, as the ability to assess risk evolve s and as policies and practices change, all registered pesticides continue to meet th at statutory standard. The public phase of registration review begins when the initial docket is opened for each case. Information on this program is provided at: http://www.epa.gov/oppsrrd1/registration_review/

.

The CTAC Preliminary Work Plan (P WP) was published March 31, 2010. The 90- day comment period ended on June 1, 2010. The Preliminary Work Plan document is

available on www.regulations.gov , docket number EPA-HQ-OPP-2010-0004.

CTAC is a formaldehyde (HCHO) releasing biocide. Therefore, this registration review case also addresses pot ential exposure to HCHO resul ting from the use of CTAC. However, this registration review case doe s not address possible aggregate risks from HCHO. When the HCHO registration review case is at the stage in which a risk assessment is conducted, aggregate risks from HCHO derived from the use of CTAC will be considered at that time. The Agency issued a Reregistration Eligibility Decision (RED) document for formaldehyde in 2008 to address potential risks associated with formaldehyde. The formaldehyde RED did not include potential exposure to HCHO resulting from the use of products containing CTAC as an active ingredient.

The Office of Pesticide Programs (OPP) developed the formaldehyde inhalation non-cancer toxicological endpoint used in the 2008 formaldehyde RED through the established reregistration process, which includes stakeholder consultation and public comment. However, the result has not been subjected to an inter-agency review or external peer review. Because of time c onstraints imposed by statutory deadline, OPP

could not consider all availa ble peer reviewed science (for example, the intentional human dosing toxicity studies). Thus , this value (10 ppb residential and 100ppb occupational) should be considered an interim value, developed solely for the purposes of the RED and subject to future revision and subsequent peer revi ew and should not be

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used in other contexts as EPA' s opinion of the best available science on the non-cancer effects of formaldehyde.

The Agency has formed a work group that is charged with developing a

harmonized non-cancer hazard characteriza tion document for formaldehyde. The Agency intends to use this non-cancer information when a ssessing the risks associated

with the antimicrobial uses of CTAC and other formaldehyde re leasers. In the near term,

the antimicrobial uses will also be assessed for cancer risks in the same manner as presented in the formaldehyde RED (i.e., a range of cancer risks using the Chemical Industry Institute of Toxicology [CIIT] m odel and the existing Integrated Risk Information System [IRIS] unit risk). On ce the IRIS update of the formaldehyde cancer unit risk is available, the Agency will adopt that value in our risk assessments. The formaldehyde risk assessments are available on EPA’s Pesticide Docket at: www.regulations.gov. The docket numb er is EPA-HQ-OPP-2008-0121.

II. COMMENTS RECEIVED ON THE PRELIMINARY WORK PLAN

EPA received submissions from two commenters during the public comment period on the initial doc ket. The comments address antic ipated toxicity, environmental fate, and ecological effects data needs. After consideration of these comments, the Agency has determined that the following thr ee studies are no longer anticipated as being needed to be required: Activated Sludge Sorption Isotherm test (835.1110), Seedling Emergence (850.4225), and Vegetative Vigor (8 50.4250). The submissions received and the Agency’s responses are explained below.

In the PWP, EPA also solicited comments on three specific topics: environmental justice, water body impairment, and trade irr itants. No comments or information were received during the public comment period concerning these issues. The timeline described in the Preliminary Work Plan rema ins as presented initially. Further, this document makes final the work plan for th e CTAC registration review process.

Commenter 1 Anticipated Toxicity Data Needs

Comment: The commenter suggests that the Agency accept a combined chronic toxicity/carcinogenicity study to fulfill both the chronic oral and carcinogenicity data requirements because performing a combined study would save over 100

animals.

Response: As stated in the PWP, the Agen cy will accept a combined chronic toxicity/carcinogencity study.

Comment: The commenter encourages the registrant to submit legible study reports for GLN 870.3250 90-Day Oral T oxicity to avoid conducting the study again, as it is currently being called in through this Registration Review.

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Response: The Agency has received and will review legible copies of GLN 870.3250, 90-Day Oral Toxicity. If the studies are determined to be “acceptable” during review, then this data requirement will be satisfied.

Commenter 2

Comment: The chemical name is misspelled throughout the document.

Response: The Agency has corrected the sp elling from 1-(3 -chloroally)-3,5,7 triaza-1-azoniaadamantane chloride to 1-(3-chloroallyl)-3,5,7-triaza-1-

azoniaadamantane in this Final Work Plan.

Anticipated Toxicity Data Needs

Comment: The registrant intends to submit legi ble copies of studies performed for GLN 870.3250 90-Day Oral Toxicity : rodent and non-rodent.

Response: The Agency has received and will review the legible copies of the studies performed for GLN 870.3250.

Comment: The registrant requests reconsideration of the Chronic Toxicity/Oncogenicity data requirement based on the belief that the hazard profile for CTAC containing products is suffici ent to make this data requirement

unnecessary: CTAC is largely negative in in vitro genotoxicity studies CTAC is negative in in vivo genotoxici ty studies CTAC shows no evidence of pre-neopla tic events in sub-chronic toxicity studies in the rat and the dog CTAC demonstrates a high Margin of Safety in various exposure

scenarios

Response : The EPA will evaluate these claims based on the submission and review of any data provided to the Agen cy. Until the EPA is able to evaluate these claims, EPA anticipates requiri ng the Chronic Toxicity/Oncogenicity requirement.

Anticipated Environmental Fate Data Needs

Comment: An Activated Sludge Sorption Isot herm test (835.1110) does not need to be performed on l-(3-Chloroallyl)- 3,5,7-Triaza-I-Azoniaadamantane Chloride (CTAC) for two reasons. First, the compound is susceptible to hydrolysis, particularly at low concen trations relevant to this test procedure. Second, sufficient information exists to predic t the extent of adsorption on activated sludge.

The hydrolysis kinetics of CTAC have b een assessed previously (Gonsior et. al., 1994). Half-lives for 50 mg/L CTAC range d from 1.1 to 2.7 days at 25°C over the pH range 5 to 9. Thus, the test guideline requirement that mixtures of the test substance and activated sludge solids are to be mixed until equilibrium is

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achieved cannot be m et since the aqueous c oncentration of the test substance will continually decrease over time in the test system.

Chemical properties for CTAC indicate that adsorption of the test substance to activated sludge will be of minimal impor tance in a wastewater treatment plant (WWTP). The water solubility of CTAC is ± 50% by weight at 20°C. The octanol/water partition coefficient is very low (log Kow = -2), consistent with the high water solubility. A log Koc = 2.5 was estimated using the OECD 121 guideline "Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Ch romatography (HPLC)" [Gonsior et. al., 2002]. This log Koc value is consistent with the high water solubility and low log Kow, confirming the position that adso rption of CTAC to sewage sludge will be of minor importance in assessing the fate of the substance in a wastewater treatment plant. In addition, CTAC is readily biodegradable (Gonsior and Goodwin, 2000). Thus, CTAC will be suscep tible to both rapid hydrolysis and biodegradation in a WWTP.

Response: The Agency concurs; an Activated Sludge Sorption Isotherm study (835.1110) is not needed and that corr esponding anticipated study requirement has been removed from this work plan.

Anticipated Ecological Effects Data Needs

Comment: The registrant believes that the Seedling Emergence and Vegetative Vigor studies requirements are inappropria te for CTAC containing products. Due to the uses of CTAC, primarily in form ulated or finished products at low concentrations, this material will not ente r terrestrial systems and therefore will be unavailable to partition into soil. Foll owing use, most CTAC residues will enter the wastewater system and be removed in wastewater treatment plants by both biodegradation and hydrolysis. Since it is un likely that terrestria l non-target plants will be exposed to CTAC due to its use patterns, additional testing on terrestrial non-target plants should not be necessary.

Response: The Agency concurs; Seedling Em ergence (850.4225) and Vegetative Vigor (850.4250) studies are not needed and those corresponding anticipated study requirements have been removed from this work plan.

III. RISK ASSESSMENT AND DATA NEEDS

Human Health Risk Assessment Status

The Agency has reviewed the hazard and exposure databases for the CTAC registration review case. As a result of this review, EPA believes risk assessments are needed to ensure that the CTAC registration review case meets the FIFRA and FFDCA

standards. Because CTAC releases formal dehyde it will also be necessary to assess

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for maldehyde exposures. The Agency will complete the human health risk assessments presented below.

 Dietary (Food) Risk Assessment - Indirect dietary (food) exposure resulting from the use of CTAC in food packaging materials.

 Residential Handler Risk Assessment - Dermal and inhalation exposure to CTAC and inhalation exposure to form aldehyde during the use of treated paints and general purpose cleaners. Residential inhalation exposure to formaldehyde during the use of CT AC treated laundry detergents.

 Residential Post-Application Risk Assessment - Incidental oral and incidental dermal exposure from wearing clothing made from textiles treated with finishing fluids preserved with CTAC.

 Occupational Handler Risk Assessment - Occupational dermal and inhalation exposure to CTAC and inhalation expos ure to formaldehyde during the open pour addition of CTAC pow der for materials preser vation, oil products, pulp and paper production and textile pro duction. Occupational dermal and inhalation exposure to CTAC and inhala tion exposure to formaldehyde during

the use of CTAC treated metal work ing fluids and preserved paints.

Dietary and Drinking Wa ter Exposure and Risk

Dietary Food Exposure

CTAC is FDA-approved for use as an indi rect food additive in adhesives and components of coatings (21 CFR 175.015); pa per and paperboard board components (21 CFR 176.170 & 21 CFR 176.180); and polyurethane resins in contact with bulk quantities of dry foods (21 CFR 177.1680). Thes e uses may result in indirect dietary food exposure. However, they were not asse ssed in the 1995 CTAC RE D. Therefore, an indirect dietary (food) exposure risk assessment is needed in support of this registration

review.

Dietary Drinking Water Exposure

The registered uses of CTAC are not lik ely to result in contamination of surface water and ground water and as a result dri nking water exposure is not expected. However, the need for a dietary drinking water exposure assessment for CTAC will be determined upon review of environmental fa te data, which the Agency anticipates requiring. The Agency anticipates that envi ronmental fate data will be useful to determine if CTAC can pass through waste-wate r treatment facilities into drinking water or migrate into residential groundwater wells as a result of its current use patterns. Therefore, the need for a dietary dri nking water assessment will be revisited upon

submission and review of the environmental fate data that are anticipated as being

needed.

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Tolerances

CTAC is permitted for use as an iner t ingredient in non-food use pesticide products (40 CFR Part 180). CTAC is also ex empt from the requirement of a tolerance when used as an inert ingredient as a pres ervative at 0.14% by we ight (wt) or less of pesticide formulati ons (40 CFR 180.920).

There are no tolerances or exemptions from tolerances for the use of CTAC as an active ingredient and no registered food uses . As previously mentioned, CTAC is FDAapproved for use as an indirect food additive in adhesives and components of coatings, paper and paperboard component s and polyurethane resins in contact with bulk quantities of dry foods.

It is noted that exemptions and regula tions for food additives under Section 409 of the Federal Food, Drug, and Cosmetic Act ( FFDCA) do not relieve the registrant of meeting the standard under Section 408 as amended by the Food Quality Protection Act (FQPA), when the active ingredie nt is subject to regulation as a food-use pesticide under the Federal Insecticide, Fungicide, and Rode nticide Act (FIFRA). Under Section 408, a determination of safety for residues of a pes ticide that may be in food is required, and as defined in Section 408(b)(2)(A)(ii), “that there is a reasonable certainty that no harm will result from aggregate exposure to the pesticide chemical resi due, including all anticipated dietary exposures and all other exposures for which there is reliable information.” EPA will be performing risk assessments to determine if tolerances or exemptions from tolerances will be needed to support th e existing registered uses of CTAC.

Aggregate and Cumulative Exposure and Risk

In examining aggregate exposure, EP A takes into account the available and reliable information concerning exposures to pesticide residues in food and drinking water, as well as non-occupati onal pesticide exposures. An aggregate risk assessment may be needed for CTAC if it is determin ed that drinking water exposure could occur

based on the environmental fate data. This assessment would consis t of the aggregation of the indirect dietary food exposure from CTAC residues in treat ed food packaging and the exposure that would occur from CTAC residue s in drinking water. If it is determined that an aggregate assessment is needed, the n eed for including residential incidental oral, dermal and inhalation exposures in the aggreg ate assessment will be determined when the toxicity data that are anticipated as bei ng required are completed and added to the database for use in endpoint selection. Ther efore, the need for an aggregate assessment will be revisited upon submission and review of the environmental fate data and human toxicology data that are antic ipated as being required.

Section 408(b)(2)(D)(v) of FFDCA requi res that, when considering whether to establish, modify, or revoke a tolerance, th e Agency consider “available information” concerning the cumulative effects of a part icular pesticide's residues and “other

substances that have a common mechanism of toxicity.” EPA has not yet determined

whether CTAC has a common mechanism with other compounds; consequently, a cumulative assessment will not be performed at this time.

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It should be noted that this registra tion review case does not address aggregate exposure from HCHO. When th e HCHO registration review case is at the point at which a risk assessment is to be conducted, a ggregate exposure from HCHO will be assessed

and the need for a cumulative HCHO assessment also will be addressed at that time.

Occupational and Residential Exposure and Risk

The Agency reviewed all available data associated with CTAC and has determined that the currently registered us es of CTAC may result in residential and occupational exposure. Therefore, the Agen cy will conduct residential (handler and postapplication) and occupational (handler) ri sk assessments to assess possible dermal, inhalation, incidental oral and incidental dermal expos ure to CTAC and possible inhalation exposure to HCHO.

Dermal exposure may possibly lead to de rmal sensitization. Du ring its review the Agency has identified dermal sensitization in open literature studies. This literature may be reviewed during the registration review process. If the Ag ency decides to rely on this open literature study, the Agency will make su re it meets all applicable standards that apply to human study ethics. Formaldehyde has been identified as one of the major allergens in the cosmetic related allergic c ontact dermatitis (Groot,et al, 1988 and Storrs, et al. 1989). Although the indi viduals involved in these inci dents may have been exposed to different types of allergens, the Agency cannot rule out the possi bility that CTAC may be related to the cosmetic related allergic co ntact dermatitis. It is also not known if the contact dermatitis is due to exposure to the CTAC parent or if it is due to exposure to the formaldehyde released by the parent. In a patch test study (Zug et. al., 2009) of 4,454 patients who had suspected contact dermatitis, 10.3% had positive reactions to Quaternium 15 and 9% had positive reactions to formaldehyde. Quaternium 15 was among the 4 most positive allergens with th e top three being nickel sulfate (19.0%), balsam of Peru (11.9%) and fragrance mix (11.5%).

Anticipated Human Health Data Needs

The Agency anticipates that the following toxicity and exposure data will be needed to conduct residential (handler and post-application) and occupational (handler) exposure risk assessments for the registered uses of CTAC.

Anticipated Toxicity Data Needs

 (GLN 870.3250) 90-Day Oral Toxicity- rodent and non-rodent

 (GLN 870.3700) Developmenta l Toxicity- non-rodent

 (GLN 870.3465) 90-Day Inhalation- rat

 (GLN 870.3800) Reproductive Study- oral

 (GLN 870.4100) Chronic Oral- rodent*

 (GLN 870.4200) Carcinogenicity *

* A combined chronic toxicity/carcinogenic ity study (OPPT 870.4300) can fulfill both the chronic oral and carcinogenicity data requirements.

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Anticipated Residential and Occupa tional Handler Exposure Data Needs

 (GLN 875.1200) Dermal Exposure

 (GLN 875.1400) Inhalation Exposure

 (GLN 875.1600) Data Re porting/Calculations

 (GLN 875.1700) Product Use Information

 (Non-Guideline Study) Textile Leaching Study

Anticipated Physical/Chemical Property Data Needs

All product chemistry data requirements have been fulfilled for CTAC. Therefore, it is anticipated that additional pr oduct chemistry data will not be needed for

CTAC.

Environmental Fate and Ecologi cal Risk Assessment Status

The Agency reviewed the environmental fate and ecological hazard databases for CTAC. Based on its review, EPA believes risk assessments are needed to ensure that the CTAC registration review case meets the FIFRA standards. The Agency will complete the environmental fate and ecological hazard risk assessments presented below. Further information and detailed justifications for the studies that are expected to be required are available in the document titled “Summary of Product Chemistry, Environmental Fate, and Ecotoxicity Data for the CTAC Regist ration Review Decision Document,” dated March 23, 2010.

 Environmental fate

 Ecological hazard

 Endangered species assessment

Environmental fate and ecological risk assessments have not been conducted for

CTAC. The use of CTAC as a materials preservative could potentially result in environmental exposure. These uses may re sult in waste water treatment plant (WWTP) discharges into terrestrial and aquatic environments. Therefore, the Agency will conduct environmental fate and ecological risk a ssessments to assess environmental exposure resulting from possible discharges into terres trial and aquatic environments. The Agency anticipates that environmental fate and ecolo gical data will be needed to conduct these

assessments.

Anticipated Environmental Fate and Ecological Data Needs

The Agency anticipates conducting envi ronmental fate and ecological risk

assessments for CTAC based on its use as a ma terials preservative. The use of CTAC as a materials preservative could potentially re sult in CTAC passing through waste water treatment plants (WWTPs), which may then be discharged into terrestrial and/or aquatic environments. Therefore, the Agency anticipates needing environmental fate and ecological toxicity data for CTAC. Should th e Agency determine at a later date that it

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needs additional data on this active ingredient or on any of its degr adates about which the Agency m ay have concern, the Agency will require such data. The environmental fate and ecological toxicity data listed below are anticipated as being needed to conduct environmental fate and ecological risk assessments.

Anticipated Environmental Fate Data Needs

 (GLN 835.2240) Photodeg radation in Water

 (GLN 835.3110) Ready Biodegradability

Anticipated Ecological Data Needs

 (GLN 850.4400) Aquatic Plant Growth (aquati c vascular plant t oxicity), Tier II dose response study on floating macrophyte ( Lemna gibba )

 (GLN 850.5400) Aquatic Plant Growth (alg al toxicity), Tier II dose response

studies on Anabaena flos-aquae (blue-green cyanobacteria) , Navicula pelliculosa (freshwater diatom), and Skeletonema costatum (marine diatom)

Endangered Species

The Agency has not conducted a risk assessment that supports a complete endangered species determination for CTAC. The ecological risk assessment planned during registration review will allow the Agency to determine whether use of CTAC has “no effect” or “may affect” federally liste d threatened or endangered species (listed species) or their designated critical habita ts. When an assessment concludes that a pesticide’s use “may affect” a listed species or its designated critical habitat, the Agency

will consult with the U.S. Fish and Wildlife Service and/or National Marine Fisheries Service (the Services ), as appropriate.

Incidents

No CTAC specific incidents have been reported in the OPP Incident Data System (IDS). CTAC (as Quaternium-15) has been used as a preservative in cosmetics and it has been reported as one of the potential causes of allergic contact dermatitis in consumers of cosmetics (Groot,et al, 1988; Storrs, et al. 1989; and O'Reilly and Murphy, 1996).

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IV. TIMELINE

The EPA has crea ted the following estimated timeline for the completion of the CTAC registration review case. The Agency anticipates requiring additional data and residential, occupational, environmental fate and ecological exposure assessments for this registration review case.

Anticipated Schedule

Activities Estimated Month/Year Phase 1: Opening the docket
Open Public Comment Period for CTAC Docket March 2010 – complete

Close Public Comment Period June 2010 – complete
Phase 2: Case Development

Develop Final Work Plan (FWP) August 2010

Issue DCI September 2011

Data Submission September 2015
Open Public Comment Period for Preliminary Risk Assessments March 2016

Close Public Comment Period June 2016

Phase 3: Registration Review Decision
Open Public Comment Period for Propos ed Reg. Review Decision September 2016

Close Public Comment Period December 2016 Final Decision and Begin Post-Decision Follow-up 2017 Total (years) 7

Next Steps

The Agency plans to develop a Data Call-In for this pesticide and expects to issue it in September 2011.

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V. GLOSSARY of T ERMS & ABBREVIATIONS

ai Active Ingredient AR Anticipated Residue ASTM American Society for Testing and Materials

AWPA American Wood Preserver’s Association

CBI Confidential Business Information

CFR Code of Federal Regulations cPAD Chronic Population Adjusted Dose

CSF Confidential Statement of Formula CSFII USDA Continuing Surveys for Food Intake by Individuals

DCI Data Call-In DEEM Dietary Exposure Evaluation Model DFR Dislodgeable Foliar Residue DNT Developmental Neurotoxicity DWLOC Drinking Water Level of Comparison

EC Emulsifiable Concentrate Formulation EDWC Estimated Drinking Water Concentration

EEC Estimated Environmental Concentration

EP End use Product EPA Environmental Protection Agency

EUP End-Use Product FDA Food and Drug Administration FIFRA Federal Insecticide, Fungicide, and Rodenticide Act FFDCA Federal Food, Drug, and Cosmetic Act FQPA Food Quality Protection Act FOB Functional Observation Battery GENEEC Tier I Surface Water Computer Model

IR Index Reservoir

LC 50 Median Lethal Concentration. A statistically derived concentration of a substance that can be expected to cause death in 50% of test animals. It is usually expressed as the weight of substance per weight or volume of water, air or feed, e.g., mg/l, mg/kg or ppm.

LD 50 Median Lethal Dose. A statistically deri ved single dose that can be expected to

cause death in 50% of the test animals when administered by the route indicated (oral, dermal, inhalation). It is expressed as a weight of substance per unit weight of animal, e.g., mg/kg.

LOC Level of Concern

LOAEL Lowest Observed Adverse Effect Level μg/g Micrograms Per Gram μg/L Micrograms Per Liter mg/kg/day Milligram Per Kilogram Per Day mg/L Milligrams Per Liter MOE Margin of Exposure

MRID Master Record Identifi cation (number). EPA's system of recording and tracking

submitted studies. MUP Manufacturing-Use Product

NA Not Applicable NAWQA USGS National Ambient Water Quality Assessment NPDES National Pollutant Discharge Elimination System

NR Not Required

NOAEL No Observed Adverse Effect Level

OPP EPA Office of Pesticide Programs OPPTS EPA Office of Prevention, Pesticides and Toxic Substances PAD Population Adjusted Dose

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16 PAIRA Pure Active Ingredient Radiolabelled PCA Percent Crop Area PDP USDA Pesticide Data Program PHED Pesticide Handler's Exposure Data

PHI Preharvest Interval phr Pounds Per Hundred ppb Parts Per Billion PPE Personal Protective Equipment ppm Parts Per Million PRZM/EXAMS Tier II Surface Water Computer Model Q 1 * The Carcinogenic Potential of a Compound, Quantified by the EPA's Cancer

Risk Model RAC Raw Agriculture Commodity RED Reregistration Eligibility Decision

REI Restricted Entry Interval

RfD Reference Dose RQ Risk Quotient RTU Ready to Use SCI-GROW Tier I Ground Water Computer Model

SAP Science Advisory Panel SF Safety Factor

SLN Special Local Need (Registrati ons Under Section 24©) of FIFRA) TGAI Technical Grade Active Ingredient

TEP Typical End-Use Product USDA United States Department of Agriculture UF Uncertainty Factor

WPS Worker Protection Standard