UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D. C. 20460 OFFICE OF PREVENTION, PESTICIDES AND TOXIC SUBSTANCES CERTIFIED MAIL Dear Registrant:

This is to inform you that the Environmental Protection Agency ( hereafter referred to as EPA or the Agency) has completed its review of the available data and public comments received related to the preliminary risk assessment for the dimethylurea herbicide diuron. The Agency has revised the human health and environmental effects risk assessments based on the comments received during the public comment period and additional data from the registrant. Based on the Agency's revised risk assessments for diuron, EPA has identified risk mitigation measures that the Agency believes are necessary to address the human health and environmental risks associated with the current use of diuron. EPA is now publishing its reregistration eligibility, and risk management decision. The Agency's decision on the individual chemical diuron can be found in the attached document entitled, " Reregistration Eligibility Decision for Diuron" which was approved on September 30, 2003. A tolerance reassessment was completed in July of 2002. This RED document contains that tolerance reassessment decision as well as the Agency's decisions on the mitigation needed for other human health and environmental risks.

A Notice of Availability for the Reregistration Eligibility Decision for Diuron is being published in the Federal Register. To obtain copies of the RED document, please contact the Pesticide Docket, Public Response and Program Resources Branch, Field and External Affairs Division ( 7506C), Office of Pesticide Programs ( OPP), USEPA, Washington, DC 20460, telephone ( 703) 305 5805. Electronic copies of the RED and all supporting documents are available on the Internet. See www. epa. gov/ pesticides/ reregistration/ status. htm.

As part of the Agency's effort to involve the public in the implementation of the Food Quality Protection Act of 1996 ( FQPA), the Agency is undertaking a special effort to maintain open public dockets and to engage the public in the reregistration and tolerance reassessment processes. During the public comment period, comments on the risk assessment were submitted by Griffin L. L. C., the technical registrant. A close out conference call with interested stakeholders was conducted on September 29, 2003, to discuss the risk management decisions and resultant changes to the diuron labels. Risks summarized in this document are those that result only from the use of diuron. The Food Quality Protection Act ( FQPA) requires that the Agency consider " available information" concerning the cumulative effects of a particular pesticide's residues and " other substances that have a common mechanism of toxicity." The reason for consideration of other substances is due to the possibility that low level exposures to multiple chemical substances that cause a common toxic effect by a common mechanism could lead to the same adverse health effect as would a higher level of exposure to any of the other substances individually. The Agency did not perform a cumulative risk assessment as part of this reregistration review of diuron because the Agency has not yet determined if there are any other chemical substances that share a common mechanism of toxicity with diuron ( see Section 6 of the Human Health Risk Assessment, dated July 9, 2003). For purposes of this risk assessment, EPA has assumed that diuron does not have a common mechanism of toxicity with other substances.

In the future, the registrant may be asked to submit, upon EPA's request and according to a schedule determined by the Agency, such information as the Agency directs to be submitted in order to evaluate issues related to whether diuron shares a common mechanism of toxicity with any other substance. If the Agency identifies other substances that share a common mechanism of toxicity with diuron, we will perform aggregate exposure assessments on each chemical, and will begin to conduct a cumulative risk assessment. The Agency has developed a framework for conducting cumulative risk assessments on substances that have a common mechanism of toxicity. This guidance was issued on January 14, 2002 ( 67 FR 2210 2214), and is available from the OPP Website at: http:// www. epa. gov/ oppfod01/ trac/ science/ cumulative_ guidance. pdf.

This RED contains the necessary labeling changes for diuron. Product labels must be revised by the manufacturer to adopt the changes set forth in Section IV of this document. Instructions for registrants on submitting revised labeling and the time frame established to do so can be found in Section V of this document.

Should a registrant fail to implement any of the risk mitigation measures outlined in this document, the Agency will continue to have concerns about the risks posed by diuron. Where the Agency has identified any unreasonable adverse effect to human health and the environment, the Agency may at any time initiate appropriate regulatory action to address this concern. At that time, any affected person( s) may challenge the Agency's action. If you have questions on this document or the proposed label changes, please contact the Special Review and Reregistration Division representative, Diane Isbell at ( 703) 308 8154.

Betty Shackleford, Acting Director Special Review and Reregistration Division Attachment Reregistration Eligibility Decision for Diuron List A Case 0046 Table of Contents Executive Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv I. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 II. Chemical Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 A. Regulatory History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 B. Chemical Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 C. Use Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 D. Estimated Usage of Pesticide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 III. Summary of Diuron Risk Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 A. Human Health Risk Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 1. Dietary Risk From Food . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 a. Toxicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 b. FQPA Safety Factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 c. Endpoints and Doses for Risk Assessment . . . . . . . . . . . . . . . 13 d. Endocrine Disruption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 e. 3,4 dichloroaniline ( 3,4 DCA) . . . . . . . . . . . . . . . . . . . . . . . . . 15 f. Potential Tetrachloroazobenzene Contamination . . . . . . . . . 15 g. Exposure Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 h. Dietary ( Food) Risk Assessment . . . . . . . . . . . . . . . . . . . . . . . 17 ( 1) Acute Dietary Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 ( 2) Chronic ( Non Cancer) Dietary Risk . . . . . . . . . . . . . . 17 ( 3) Cancer Dietary Risk from Food . . . . . . . . . . . . . . . . . 18 2. Dietary Risk from Drinking Water . . . . . . . . . . . . . . . . . . . . . . . . . . 19 a. Surface Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 b. Ground Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 c. Drinking Water Risk Estimates . . . . . . . . . . . . . . . . . . . . . . . 23 3. Diuron: Residential Exposure and Risk . . . . . . . . . . . . . . . . . . . . . . 24 a. Toxicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 b. Residential Handler Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 ( 1) Exposure Scenarios, Data, & Assumptions . . . . . . . . . 26 ( 2) Residential Handler Risk Characterization . . . . . . . . 28 c. Residential Postapplication Risk Characterization . . . . . . . . 29 ( 1) Exposure Scenarios, Data, & Assumptions . . . . . . . . . 29 ( 2) Residential Postapplication Risk Characterization . . 30 4. Aggregate Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 a. Acute Aggregate Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 b. Short Term Aggregate Risk . . . . . . . . . . . . . . . . . . . . . . . . . . 31 c. Chronic ( Non Cancer) Aggregate Risk . . . . . . . . . . . . . . . . . 32 d. Cancer Aggregate Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 5. Occupational Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 a. Toxicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 b. Agricultural Handler Exposure . . . . . . . . . . . . . . . . . . . . . . . 36 c. Agricultural Handler Non Cancer Risk . . . . . . . . . . . . . . . . . 39 d. Agricultural Handler Cancer Risk . . . . . . . . . . . . . . . . . . . . . 47 e. Handler Exposure from Antimicrobial Use: Mildewcide in Paints, Stains, Solvents, Adhesives, and Coatings . . . . . . . . . 53 f. Handler Risk from Antimicrobial Use: Mildewcide in Paints, Stains, Solvents, Adhesives, and Coatings . . . . . . . . . . . . . . . 55 g. Handler Exposures: Algaecide Use for Use in Commercial Fish Ponds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 h. Handler Risks: Algaecide Use for Use in Commercial Fish Ponds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 i. Postapplication Occupational Risk . . . . . . . . . . . . . . . . . . . . . 60 ( 1) Data Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 ( 2) Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 j. Human Incident Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 B. Environmental Risk Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 1. Environmental Fate and Transport . . . . . . . . . . . . . . . . . . . . . . . . . . 64 2. Toxicity ( Hazard) Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 a. Toxicity to Terrestrial Organisms . . . . . . . . . . . . . . . . . . . . . 66 b. Toxicity to Aquatic Organisms . . . . . . . . . . . . . . . . . . . . . . . . 67 c. Toxicity to Non target Plants . . . . . . . . . . . . . . . . . . . . . . . . . 68 3. Exposure and Risk Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 a. Risk Calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 b. Exposure and Risk to Non target Terrestrial Organisms . . . 70 ( 1) Avian Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 ( 2) Mammalian Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 ( 3) Risk to Non target Insects . . . . . . . . . . . . . . . . . . . . . . . . 73 c. Exposure and Risk to Non target Aquatic Organisms . . . . . 73 ( 1) Surface Water Resources Assessment . . . . . . . . . . . . . . . 74 ( 2) Risk to Fish and Aquatic Invertebrates . . . . . . . . . . . . . . 74 d. Exposure and Risk to Non target Terrestrial and Aquatic Plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 4. Ecological Incidents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 5. Endangered Species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 IV. Risk Management, Reregistration and Tolerance Reassessment Decisions . . . . . . 81 A. Determination of Reregistration Eligibility . . . . . . . . . . . . . . . . . . . . . . . . . . 81 B. Public Comments and Responses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 C. Regulatory Position . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 1. FQPA Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 a. " Risk Cup" Determination . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 b. Determination of Safety for U. S. Population . . . . . . . . . . . . . 82 c. Determination of Safety for Infants and Children . . . . . . . . . 83 d. Endocrine Disruptor Effects . . . . . . . . . . . . . . . . . . . . . . . . . . 83 e. Cumulative Risks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 f. Tolerance Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 ( 1) Codex Harmonization . . . . . . . . . . . . . . . . . . . . . . . . . 90 D. Risk Management and Rationale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 1. Human Health Risk Management . . . . . . . . . . . . . . . . . . . . . . . . . . . 92 a. Dietary ( Food) Risk Mitigation . . . . . . . . . . . . . . . . . . . . . . . 92 b. Drinking Water Risk Mitigation . . . . . . . . . . . . . . . . . . . . . . 93 c. Residential Risk Mitigation . . . . . . . . . . . . . . . . . . . . . . . . . . 93 ( 1) Residential Handler Mitigation . . . . . . . . . . . . . . . . . . 94 ( 2) Residential Postapplication Risk Mitigation . . . . . . . 94 d. Aggregate Risk Mitigation . . . . . . . . . . . . . . . . . . . . . . . . . . . 94 ( 1) Acute Aggregate Risk . . . . . . . . . . . . . . . . . . . . . . . . . 94 ( 2) Short term Aggregate Risk . . . . . . . . . . . . . . . . . . . . . 94 ( 3) Chronic ( Non Cancer) Aggregate Risk . . . . . . . . . . . . 94 ( 4) Chronic ( Cancer) Aggregate Risk . . . . . . . . . . . . . . . . 95 e. Occupational Risk Mitigation . . . . . . . . . . . . . . . . . . . . . . . . . 95 ( 1) Handler Risk Mitigation . . . . . . . . . . . . . . . . . . . . . . . 95 ( 2) Post application Risk Mitigation . . . . . . . . . . . . . . . . 98 2. Environmental Risk Mitigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 3. Other Labeling Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 a. Endangered Species Statement . . . . . . . . . . . . . . . . . . . . . . . . 99 b. Spray Drift Management . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 V. What Registrants Need to Do . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 A. Manufacturing Use Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 1. Additional Generic Data Requirements . . . . . . . . . . . . . . . . . . . . . . 103 2. Labeling for Manufacturing Use Products . . . . . . . . . . . . . . . . . . . 104 B. End Use Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 1. Additional Product Specific Data Requirements . . . . . . . . . . . . . . 104 2. Labeling for End Use Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 C. Existing Stocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 i Diuron Reregistration Eligibility Decision Team Office of Pesticide Programs:

Biological and Economic Analysis Assessment Bill Chism Alan Halvorson Environmental Fate and Effects Risk Assessment Ibrahim Abdel Saheb William Eckel Richard Lee Dana Spatz Health Effects Risk Assessment Carol Christensen Ken Dockter Sherrie Kinard Yung Yang Registration Support Dan Rosenblatt Jim Tompkins Risk Management Diane Isbell ii Glossary of Terms and Abbreviations AGDCI Agricultural Data Call In ai Active Ingredient aPAD Acute Population Adjusted Dose AR Anticipated Residue BCF Bioconcentration Factor 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 DWLOC Drinking Water Level of Comparison. EC Emulsifiable Concentrate Formulation EEC Estimated Environmental Concentration 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 G Granular Formulation GENEEC Tier I Surface Water Computer Model GLN Guideline Number HAFT Highest Average Field Trial IR Index Reservoir LC50 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. LD50 Median Lethal Dose. A statistically derived 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 LOD Limit of Detection LOAEL Lowest Observed Adverse Effect Level MATC Maximum Acceptable Toxicant Concentration

g/ g Micrograms Per Gram

g/ L Micrograms Per Liter mg/ kg/ day Milligram Per Kilogram Per Day mg/ L Milligrams Per Liter MOE Margin of Exposure MRID Master Record Identification ( number). EPA's system of recording and tracking studies submitted. MUP Manufacturing Use Product NA Not Applicable NAWQA USGS National Water Quality Assessment NCFAP National Center for Food and Agricultural Policy NPDES National Pollutant Discharge Elimination System iii NR Not Required NOAEL No Observed Adverse Effect Level OP Organophosphate OPP EPA Office of Pesticide Programs OPPTS EPA Office of Prevention, Pesticides and Toxic Substances PAD Population Adjusted Dose PCA Percent Crop Area PDP USDA Pesticide Data Program PHED Pesticide Handler's Exposure Data PHI Preharvest Interval ppb Parts Per Billion PPE Personal Protective Equipment ppm Parts Per Million PRZM/ EXAMS Tier II Surface Water Computer Model Q1* 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 SCI GROW Tier I Ground Water Computer Model SAP Science Advisory Panel SF Safety Factor SLC Single Layer Clothing SLN Special Local Need ( Registrations Under Section 24 © ) of FIFRA) TGAI Technical Grade Active Ingredient TRED Tolerance Reassessment Progress and Risk Management Decision TRR Total Radioactive Residue USDA United States Department of Agriculture USGS United States Geological Survey UF Uncertainty Factor UV Ultraviolet WPS Worker Protection Standard iv Executive Summary EPA has completed its review of public comments on the preliminary risk assessments and is issuing its risk management decision for diuron. The revised risk assessments are based on a review of the required target data base supporting the use patterns of currently registered products and additional information received during the public comment periods. After considering the risks identified in the revised risk assessment, EPA developed its risk management decision for uses of diuron that pose risks of concern. Risks from N'( 3 chlorophenyl) N, Ndimethyl urea ( MCPDMU) ( water only) 3,4 dichlorophenylurea ( DCPU) and 3( 3,4 dichlorophenyl) 1 methylurea ( DCPMU), the primary metabolites of diuron, are also considered in the assessment. The decision is discussed fully in this document. A tolerance reassessment was completed in July of 2002. For completeness, the results of the tolerance reassessment are incorporated in this document, including additional information on surface water monitoring.

Diuron is registered for pre and post emergent herbicide treatment of both crop and noncrop areas, as a mildewcide and preservative in paints and stains, and as an algaecide in commercial fish production, residential ponds and aquariums. Diuron was first registered in 1967.

Estimates for total annual domestic use average approximately nine to ten million pounds of active ingredient. Approximately two thirds is used on agricultural crops and the remaining one third on non crop areas. Diuron is used on 33 crops. Crops with the highest percent crop treated are citrus, berries, asparagus and pineapple. In terms of pounds applied, oranges and cotton account for the greatest agricultural use. Right of way applications ( e. g., the area around railroad tracks) are the greatest non agricultural use of diuron, with approximately 2 to 3 million pounds applied annually.

Risks summarized in this document are those that result only from the use of diuron. The Food Quality Protection Act ( FQPA) requires that the Agency consider " available information" concerning the cumulative effects of a particular pesticide's residues and " other substances that have a common mechanism of toxicity." The reason for consideration of other substances is due to the possibility that low level exposures to multiple chemical substances that cause a common toxic effect by a common mechanism could lead to the same adverse health effect as would a higher level of exposure to any of the other substances individually. The Agency did not perform a cumulative risk assessment as part of this reregistration review of diuron because the Agency has not yet determined if there are any other chemical substances that share a common mechanism of toxicity with diuron ( see Section 6 of the Human Health Risk Assessment, dated July 9, 2003). For purposes of this risk assessment, EPA has assumed that diuron does not have a common mechanism of toxicity with other substances. v Dietary Risk  Food EPA's dietary risk analysis evaluated acute, chronic ( non cancer) and cancer risk for diuron. Anticipated residues from field trial data were used to estimate the dietary exposure to diuron from the diets of the U. S. population as well as certain population subgroups. The field trials were conducted at the highest application rates for the crop tested and therefore, the residues from these trials are considered high end. It should be noted that the U. S. Department of Agriculture's Pesticide Data Program ( PDP) monitoring data are available for diuron alone, indicating no detectable residues of the parent compound in citrus, milk and other sampled commodities monitored for diuron. However, these data have not been used in the risk assessment because the PDP program only monitored for diuron, the parent compound, and did not monitor for the metabolites.

The Agency has not performed an acute dietary risk assessment of diuron because no adverse effects attributed to a single exposure were identified in any available study. The chronic non cancer dietary analysis indicates all risk estimates are below EPA's level of concern for all population subgroups. The chronic dietary risk estimate for food is about 3% of the chronic PAD for the U. S. population and about 7% of the chronic PAD, for the highest exposed population subgroup, children ( 1 6 years). The estimated cancer dietary risk associated with the use of diuron shows a lifetime risk estimate of 1.68 x 10 6 for the general population. However, the Agency does not believe potential dietary cancer risk to be of concern because the residues used in the calculations are from field trials conducted at the highest application rates and some processing data are still outstanding. Therefore, the exposure calculation is a conservative estimate.

Dietary Risk  Drinking Water Drinking water exposure to pesticides can occur through groundwater and surface water contamination. For chronic risk from diuron, drinking water monitoring data from South Florida Water Management District and the California Department of Pesticide Regulation were used in addition to USGS NAWQA data from the South Florida, Georgia Florida Coastal Plain and Apalachicola Chattahoochee Flint River were used to determine the estimated environmental concentrations ( EECs) in surface water. Estimated drinking water concentrations for ground water are based on the SCI GROW model, which is a Tier I assessment that provides a conservative estimate. The modeled estimates indicate that ground water concentrations of diuron and its metabolites are not of concern.

The estimated environmental concentrations ( EECs) for surface water from monitoring data (< 1 ppb) do not exceed the drinking water level of comparison ( DWLOC) of 28 ppb and are not of concern for the general population or any sub group.

For diuron potential cancer risk, EPA has considered average values from monitoring data ranging from 0.16 to 0.28 ppb, yielding risk estimates in the 1 x 10 6 range. vi For the degradate MCPDMU, the EEC for surface water has been estimated to be < 1ppb, using monitoring data. The drinking water assessment for MCPDMU can be further refined with additional environmental fate data. These data are required.

Residential Risk There are two potential sources of exposure to diuron in a residential setting  as an algaecide in ponds and aquariums, and as a preservative or a mildewcide in paints. Exposure from the dermal and inhalation routes are combined for each residential use.

The algaecide products are formulated as tablets/ blocks and as a liquid. There are no exposure data for the use of the algaecide tablets/ blocks. Since the products are formulated as tablets/ blocks and dissolve in less than 5 minutes, minimal exposure is expected and was not quantified. The liquid is used at a rate of one teaspoon ( 5 ml) for every 10 gallons of aquarium or pond water, once a month or when algae growth reappears. Residential exposure may result from measuring the liquid and pouring the liquid into the aquarium or pond. Exposure is expected to be short term ( 1 to 30 days). These risks are not of concern.

Residential painters using paints and stains were assumed to use airless sprayers and paint brushes. Exposure is expected to be short term ( 1 to 30 days). For homeowners, the airless sprayer is assumed to be used for outdoor applications only. For indoor applications, EPA assumed that painting would be restricted to small rooms such as bathrooms ( high potential for moisture) where an airless sprayer is unlikely to be used. These risks are not of concern.

There are no residential uses that would result in chronic exposure to diuron. Because less than 1 percent of all paint contains diuron, cancer risk from residential use is expected to be negligible.

Diuron Aggregate Risk An aggregate risk assessment looks at the combined risk from dietary exposure ( food and drinking water pathways) as well as exposures from non occupational sources ( e. g., residential uses).

Acute Aggregate Risk. There are no adverse effects expected from a single exposure to diuron; therefore, an acute risk assessment was not conducted.

Short term Aggregate Risk. Short term aggregate exposure takes into account residential exposure plus chronic exposure to food and water. Short term aggregate risks from food, residential inhalation, and drinking water are not of concern.

Chronic ( Non cancer) Aggregate Risk. The chronic ( non cancer) aggregate risk assessment addresses exposure to diuron residues in food and water; there are no diuron uses that vii could result in chronic residential exposure. Monitoring data from the South Florida Water Management District and the California Department of Pesticide Regulation were used in addition to USGS NAWQA data from the South Florida, Georgia Florida Coastal Plain and Apalachicola Chattahoochee Flint River. The estimated environmental concentration ( EEC) for surface water (< 1 ppb) does not exceed the drinking water level of comparison ( DWLOC) of 28 ppb for the most sensitive population subgroup ( children 1 6). Therefore, the chronic non cancer DWLOCs are greater than the surface water EECs indicating that chronic dietary ( food + water) risks are below EPA's level of concern. Chronic aggregate risk is also below EPA's level of concern.

Chronic ( Cancer) Aggregate Risk. Dietary risk from food is estimated at 1.68 x 10 6 based on field trial data and assuming maximum application rates. This estimate can be refined with additional residue data. Based on monitoring data, drinking water cancer risk is estimated in the 1 x 10 6 range. Exposure from residential uses is negligible. Although the combined risk exceeds 1 x 10 6, EPA believes that, given the weight of evidence, diuron cancer risk is not of concern. The Agency does not apply the negative risk standard for cancer ( 1 x 10 6 or one in a million) as a bright line test because of the lack of precision in the quantitative cancer risk assessment. There are protective assumptions in both the toxicological data used to derive the cancer potency of a substance and in the exposure calculations.

MCPDMU Aggregate Risk As discussed above ( under Drinking Water Dietary Risk), diuron degrades in water to MCPDMU. Because no toxicology data are available for MCPDMU, the Agency used data from a structurally similar compound, monuron, to assess the potential cancer risk from MCPDMU. Based on the algaecidal use in commercial fish ponds, the dietary cancer risk from catfish alone is 1.02 x 10 7 and is not of concern.

Monitoring data, adjusted to account for all potential metabolites, indicate that environmental concentrations of MCPDMU would be < 1 ppb, which is less than the calculated DWLOC of 2 ppb. Thus, the aggregate risk of MCPDMU is not of concern.

Occupational Risk The Agency has identified 31 handler scenarios resulting from mixing/ loading and applying diuron for crop and non crop uses. Of the 31 scenarios, all short and intermediate term exposures resulted in a Margin of Exposure ( MOE) at or near the target of 100 with personal protective equipment ( PPE) and engineering controls ( e. g., closed mixing and loading systems), as appropriate.

For the occupational paint assessment, painters using an airless sprayer ( MOE = 56) is of concern ( with PPE).

For the cancer assessment, the following scenarios are potentially of concern ( with PPE): viii applying with a right of way sprayer ( risk = 1.3e 4); applying in an industrial/ commercial setting with a high pressure handwand ( risk = 2.4e 4); mixing/ loading/ applying wettable powder products with a low pressure handwand ( risk = 1.5e 4); loading and applying with a gravity feed backpack spreader ( risk = 1.6e 4); and loading and applying with a belly grinder ( risk = 3.1e 4).

Ecological Risk Diuron is persistent and is stable to hydrolysis. Calculated half lives in aqueous and soil photolysis are 43 and 173 days, respectively. Half lives in laboratory aerobic and anaerobic soil metabolism studies are 372 and 1000 days, respectively. However, in a viable laboratory aquatic system, degradation occurred with half lives of 33 and 5 days in aerobic and anaerobic systems, respectively. In soil, the half lives of diuron and its degradate DCPMU range from 73 to 139 days and 217 to 1733 days, respectively.

Most of the RQ values are 9 or below, including birds ( acute), mammals, freshwater fish, estuarine fish, freshwater invertebrates, and estuarine invertebrates. The highest RQ value for non target aquatic plants from railroad/ right of way treatment at the maximum application rate is 172. The RQs for non target terrestrial plants range from 1 to 77 for acute risk.

Endangered Species EPA has completed an " Effects Determination" for endangered and threatened salmon and steelhead species and the potential for indirect effects on these fish from damage to their aquatic plant cover in water bodies in California and the Pacific Northwest.

The Agency has concluded that agricultural crop uses of diuron will have no effect on Pacific salmon and steelhead except at certain high use rates, on walnuts, filberts, and peaches, and that non crop uses may affect 25 salmon and steelhead evolutionarily significant units ( ESUs). For those ESUs that may be affected by diuron use, EPA will consult with the National Marine Fisheries Service to determine what protective measures are needed. The protective measures are communicated to the public in county specific bulletins. Other species and geographic areas have not yet been evaluated. For additional information, please see the document titled, " Diuron, Analysis of Risks to Endangered and Threatened Salmon and Steelhead," dated July 30, 2003. See http:// www. epa. gov/ oppfead1/ endanger/ effects/ diuron_ analysis_ final2. pdf. ix Risk Mitigation Summary To mitigate risks of concern posed by the use of diuron, EPA considered the mitigation proposed by the technical registrant, as well as risk mitigation ideas from other interested parties, and has decided on a number of label amendments to address the worker, residential and ecological concerns. A summary of the risk mitigation is listed below. A complete discussion of the risk assessments, and the necessary label amendments to mitigate risks posed by the use of diuron, are presented in Chapter IV of this RED.

° All wettable powder products will be voluntarily canceled.

° Reduction in application rate and increased treatment intervals, and limit the number of applications for some crops.

° Use of the backpack sprayer is prohibited.

° Implement use of PPE and engineering controls for some workers.

° Eliminate aerial applications except for rights of way, alfalfa, cotton, winter barley, winter wheat, sugarcane, and grass seed crops.

° Best management practices to reduce spray drift.

Conclusions The Agency is issuing this Reregistration Eligibility Document ( RED) for diuron, as announced in a Notice of Availability published in the Federal Register. This RED document includes guidance and time frames for complying with any required label changes for products containing diuron. With the addition of the label restrictions and amendments detailed in this document, the Agency has determined that all currently registered uses of diuron are eligible for reregistration.

The risk assessments for diuron are based on the best scientific data currently available to the Agency and are adequate for regulatory decision making. 1 I. Introduction The Federal Insecticide, Fungicide, and Rodenticide Act ( FIFRA) was amended in 1988 to accelerate the reregistration of products with active ingredients registered prior to November 1, 1984. The amended Act calls for the development and submission of data to support the reregistration of an active ingredient, as well as a review of all submitted data by the U. S. Environmental Protection Agency ( referred to as EPA or " the Agency"). Reregistration involves a thorough review of the scientific database underlying a pesticide's registration. The purpose of the Agency's review is to reassess the potential hazards arising from the currently registered uses of the pesticide, to determine the need for additional data on health and environmental effects, and to determine whether or not the pesticide meets the " no unreasonable adverse effects" criteria of FIFRA.

On August 3, 1996, the Food Quality Protection Act of 1996 ( FQPA) was signed into law. This Act amends FIFRA to require tolerance reassessment during reregistration. It also requires that by 2006, EPA must review all tolerances in effect on the day before the date of the enactment of the FQPA. The FQPA also amends the FFDCA to require a safety finding in tolerance reassessment based on factors including an assessment of cumulative effects of chemicals with a common mechanism of toxicity.

Diuron is used as a pre and post emergent herbicide treatment on a variety of both crop and non crop areas. It is also used as a mildewcide in paints and stains, and as an algaecide in commercial fish production. At this time, the Agency does not have data available to determine with certainty whether diuron has a common mechanism of toxicity with other pesticides. Therefore, for the purposes of this risk assessment, the Agency has assumed that diuron does not share a common mechanism of toxicity with other pesticides. If the Agency identifies other substances that share a common mechanism of toxicity with diuron, EPA will consider whether a cumulative assessment is warranted. The Agency has developed a framework for conducting cumulative risk assessments on substances that have a common mechanism of toxicity. This guidance was issued on January 16, 2002 ( 67 FR 2210 2214), and is available from the OPP Website at: http:// www. epa. gov/ oppfod01/ trac/ science/ cumulative_ guidance. pdf.

This document consists of six sections. Section I, Introduction, contains the regulatory framework for reregistration/ tolerance reassessment. Section II, Chemical Overview, provides a profile of the use and usage of the chemical and its regulatory history. Section III, Summary of Diuron Risk Assessments, gives an overview of the revised human health and environmental effects risk assessments resulting from public comments and other information. Section IV, Risk Management: Reregistration and Tolerance Reassessment, presents the Agency's reregistration eligibility and risk management decisions. Section V, What Registrants Need to Do, summarizes label changes needed to implement the risk mitigation measures outlined in Section IV. The Appendices, provide information on how to access related documents, and list Data Call In ( DCI) information. The revised risk assessments and related addenda are not included in this document, but are available on the Agency's web page www. epa. gov/ pesticides, and in the Public Docket. II. Chemical Overview 2 A. Regulatory History Diuron has been registered in the United States since 1967 for use as an herbicide, mildewcide and algaecide.

A Registration Standard, titled " Guidance for the Reregistration of Pesticide Products Containing Diuron as the Active Ingredient" was released in 1983. The Registration Standard involved a thorough review of the scientific data base underlying pesticide registrations and an identification of essential but missing studies which may not have been required when the product was initially registered or studies that were considered insufficient. Subsequent Data Call Ins ( DCIs) were issued in 1990, and 1995 for diuron. This Reregistration Eligibility Decision ( RED) reflects a reassessment of all data submitted to date.

There is a Section 18, Emergency Exemption registration for diuron use on catfish in the states of Arkansas, Louisiana, and Mississippi. The Agency is considering the catfish use for registration under Section 3 of FIFRA. Therefore, the risks from the catfish use have been assessed and are discussed in this document.

This Reregistration Eligibility Decision document evaluates risks from all currently registered uses, including agricultural food and non food crops; ornamental trees, flowers, and shrubs; paints and coatings; ornamental fish and catfish production; rights of way and industrial sites. Residential uses include ponds, aquariums, and paints.

In an effort to promote transparency of the reregistration process and public acceptance of regulatory decisions, the Agency, in cooperation with the U. S. Department of Agriculture ( USDA), is working to modify the reregistration process. An interim process has been established to provide opportunities for stakeholders to ask questions and provide input on the risk assessment and risk mitigation strategies, via conference calls and other formats. See Chapter IV, Section B for a detailed description of the modified process. A Tolerance Reassessment Progress and Risk Management Decision ( TRED) was issued in July 2002. This RED document contains the tolerance reassessment decision as well as the Agency's decisions on the mitigation needed for other human health and environmental risks.

A risk mitigation meeting was held with stakeholders on August 6, 2003. Stakeholders and research organizations provided new information regarding use rates, acreage, application frequency, application equipment, etc., which enabled EPA to significantly refine the occupational risk assessment. Also, a close out conference call was conducted on September 29, 2003, with EPA, USDA, the registrants, and other stakeholders ( e. g., growers, commodity groups, land grant universities), to discuss the risk management decisions and resultant changes to the diuron labels.

B. Chemical Identification The Agency has reviewed the metabolism of diuron in plants and animals from the results 3 NH N O Cl Cl CH 3 CH 3 NH NH O Cl Cl CH 3 NH NH 2 O Cl Cl of wheat, corn, orange, ruminant, and poultry studies together with the environmental fate studies conducted in soil and water and has identified the following 14C containing residues in plants: diuron, 3,4 dichlorophenylurea ( DCPU), and 3( 3,4 dichlorophenyl) 1 methylurea ( DCPMU). No other dichloroaniline containing metabolites were identified. The majority of radioactivity in the aqueous/ organic fractions was characterized as polar unknowns. Radiovalidation of a GC/ ECD data collection method which is similar to the enforcement method suggested that a good portion of these polar metabolites can be converted to 3,4 DCA. The chemical names and structures of these compounds are depicted in Figure A.

Figure A. Chemical structures of diuron residues of concern.

Diuron: 3( 3,4 dichlorophenyl) 1,1 dimethylurea DCPMU; IN 15654: 3( 3,4 dichlorophenyl) 1 methylurea DCPU; IN R915: 3,4 dichlorophenylurea ° Common Name: Diuron ° Chemical Name: 3( 3,4 dichlorophenyl) 1,1 dimethylurea ° Chemical Family: dimethylurea ° CAS Registry Number: 330 54 1 ° OPP Chemical Code: 035505 ° Empirical Formula: C 9 H 10 Cl 2 N 2 O ° Molecular Weight 233.1 ° Vapor Pressure: 2 x 10 7 mm Hg at 30

C ° Basic Manufacturer: Griffin LLC Table 1. Diuron Physical and Chemical Properties 4 Guideline Number Physical and Chemical Property Data 830 6302 Color White 830 6303 Physical State Crystal 830 6304 Odor None 830 7200 Melting Point 158o C 830 7840 Water Solubility 42 ppm @ 25o C 830 7950 Vapor Pressure 2 x 10 7 mm Hg @ 30o C 830 7550 Partition Coefficient ( Log P ow) 2.68 830 6320 Corrosion characteristics Not corrosive 830 6313 Stability to normal and elevated temperatures, metals, and metal ions Stable for 2 yrs. in double polyethylene bag inside a fiber drum under warehouse conditions. Metals and metal ion data not given.

C. Use Profile The following is information on the currently registered uses including an overview of use sites and application methods. A detailed table of the uses of diuron eligible for reregistration is contained in Appendix A.

Type of Pesticide Diuron is a substituted urea herbicide for the control of a wide variety of annual and perennial broad leaved and grassy weeds on both crop and non crop sites. The mechanism of herbicidal action is the inhibition of photosynthesis.

Use Sites Products containing diuron are intended for both occupational and residential uses. Occupational uses include agricultural food and non food crops; ornamental trees, flowers, and shrubs; paints and coatings; ornamental fish ponds, and catfish production; rights of way and industrial sites. Residential uses include ponds, aquariums, and paints.

Use Limitations The plantback intervals for the various crops on diuron labels range from 2 to 12 months. 5 In addition, rotational crop restrictions are listed on individual labels, and further restrictions limit applications to crops grown in certain soils or soil types.

For more information about the plantback interval, please see the document titled, " Residue Chemistry Chapter For The Diuron Reregistration Eligibility Decision ( RED) Document," dated 7/ 29/ 2001.

Target Pests Diuron is used for pre emergence control of annual grass and broadleaf weeds and some perennial weeds.

Formulation Types Formulated as wettable powder ( 25% to 80% ai), liquid ( up to 40% ai), emulsifiable concentrate ( 2% to 80% ai), dry flowable ( 40% to 80 % ai), flowable concentrate ( 19% to 47.5% ai), granular ( 0.2% to 20% ai), pellet/ tablet ( 0.51% to 19% ai), and ready to use solution ( 0.67% to 19% ai).

Methods and Rates of Application Diuron is applied using the following equipment: groundboom sprayer, aerial equipment, chemigation, rights of way sprayer, high pressure handwand, low pressure handwand, tractordrawn spreader, granular backpack spreader, push type spreader, airless sprayer, paintbrush, shaker type applicator, backpack sprayer, belly grinder, and by hand. Products intended for residential use may be applied using a spoon, by hand, by airless sprayer, or by paintbrush/ roller.

For agricultural uses, labeled single application rates range from 0.2 to 6.4 lbs active ingredient ( ai) per acre ( A). For citrus, a yearly maximum of 9.6 lbs ai/ A is on current labels. For non agricultural uses labeled rates range from 0.8 lbs to 87 lbs ai/ acre; however, the highest application rate on an actively marketed label is 12 lbs ai/ acre. The risk assessments evaluate a range of rates; however, this overview will focus on application rates of 12 lbs ai/ A or lower. The higher rates on the other products are not being supported by the registrant and will be removed from product labels. Diuron may be applied to non agricultural areas 1 to 2 times per year. For the mildewcide and preservative in paint uses, label rates go up to 0.053 lbs ai/ gal. and for algaecidal uses labeled rates are less than 1/ 100th % ai/ gal. 6 Timing of Application One to four applications per season may be applied in 60 day intervals ( on current labels); for most uses only one application is used.

D. Estimated Usage of Pesticide Estimates for total annual domestic use of diuron average approximately nine to ten million pounds of active ingredient. Approximately two thirds are used on agricultural crops and the remaining one third on non crop areas. Crops with the highest percent crop treated are the citrus, various berries, pineapple, and asparagus. In terms of pounds applied, oranges and cotton account for the greatest agricultural use. Right of way applications ( e. g., the area around railroad tracks) are the greatest non agricultural use of diuron, with approximately 2 to 3 million pounds applied annually. These estimates were derived from a variety of published and proprietary sources available to the Agency. Table 2 summarizes the best available estimates for the pesticide usage of diuron.

Table 2. Diuron Crop Usage Summary Site Acres Grown ( 000) Acres Treated ( 000) % of Crop Treated Pounds AI Applied ( 000) Average Application Rate States of Most Usage Wtd Avg Est Max Wtd Avg Est Max Wtd Avg Est Max Pounds ai/ Acre Per Year Pounds Applied Per Year Pounds ai Per Acre Applied (% of total lb ai used on this site)

Blackberries 5 3 4 53% 73% 5 7 1.7 1.1 1.5 OR 100%

Blueberries 59 17 22 29% 37% 21 29 1.2 1.1 1.1 MI NJ OR 84%

Raspberries 13 2 4 13 29 2 4 1.2 1.1 1.1 WA OR 100%

Grapes 869 87 155 10 18 100 200 1.2 1.0 1.2 CA NY PA 81%

Grapefruit 189 89 147 47 78 240 462 2.7 1.7 1.6 FL TX 92%

Lemons 67 18 35 26 53 39 86 2.2 1.3 1.7 CA AZ 98%

Oranges 927 470 578 51 62 1,210 1,710 2.6 1.7 1.5 FL CA 97%

Citrus, Other 62 24 39 38 63 65 118 2.8 1.7 1.6 FL AZ 93%

Limes 6 2 3 33 49 5 7 2.4 1.8 1.3

Tangelos 12 6 7 47 58 17 26 2.9 2.1 1.4 FL 100%

Tangerines 37 11 16 30 43 22 31 2.0 1.7 1.1 FL CA 100%

Temples 7 3 5 51 80 9 18 2.6 1.9 1.4 FL 100%

Apples 520 65 113 13 22 100 188 1.5 1.1 1.4 NY WA PA ID OH 65%

Pears 74 7 15 9 20 15 31 2.2 1.2 1.8 OR CA WA 81% Site Acres Grown ( 000) Acres Treated ( 000) % of Crop Treated Pounds AI Applied ( 000) Average Application Rate States of Most Usage Wtd Avg Est Max Wtd Avg Est Max Wtd Avg Est Max Pounds ai/ Acre Per Year Pounds Applied Per Year Pounds ai Per Acre Applied (% of total lb ai used on this site)

7 Pome Fruit, Other 31 4 6 13 19 10 15 2.6 1.8 1.5 FL 98%

Avocados 80 1 2 1 2 1 3 1.7 1.3 1.3 FL 100%

Cherries, Sweet 52 0.2 0.8 0.3 2 0.3 1.7 2.1 1.9 1.1 MI OR 93%

Cherries, Tart 49 1 4 3 8 3 9 2.1 1.2 1.8 MI 88%

Nectarines 36 0.1 0.5 0.3 1 0.2 0.8 1.6 1.0 1.6

Olives 36 8 12 24 35 14 19 1.6 1.2 1.4

Peaches 260 25 56 10 21 38 81 1.5 1.0 1.4 GA SC NJ PA WV CA 74%

Plums/ Prunes 147 4 6 3 4 2 3 0.6 1.2 0.5 CA OR GA 85%

Almonds 489 3 10 1 2 6 15 2.2 1.2 1.8 CA 100%

Hazelnuts/ Filberts 29 4 8 14 28 5 9 1.2 1.0 1.2 OR 100%

Macadamia & Pistachio 75 4 7 5 10 9 18 2.5 2.4 1.0

Pecans 452 13 26 3 6 28 58 2.1 1.0 2.1 GA AZ NM CA 80%

Walnuts 215 26 43 12 20 51 98 2.0 1.1 1.8 CA 98%

Asparagus 83 45 56 53 68 74 80 1.7 1.2 1.3 CA MI WA 96%

Barley 6612 8 38 0.1 1 1 6 0.2 1.0 0.2

Corn 77779 19 79 0.02 0.1 18 83 0.9 1.0 0.9 LA MS PA TX 87%

Mint 167 68 91 41 54 22 29 0.3   CA ID 90%

Oats 2667 3 8 0.1 0.3 2 5 1.6   OR WA 100%

Seed Crops 1249 547 683 44 55 678 848 1.2   OR ID 88%

Sorghum 10216 14 52 0.1 1 9 37 0.6 1.0 0.6 TX NM 91%

Sugarcane 882 36 76 4 9 42 89 1.2 1.1 1.0 LA 93%

Wheat, Spring 20599 14 38 0.1 0.2 8 20 0.5 1.0 0.5 ID OR 88%

Wheat, Winter 43721 150 319 0.3 1 140 380 0.9 1.0 0.9 OR OK WA 87%

Alfalfa 23665 190 380 1 2 240 350 1.3 1.0 1.3 CA KS AZ NV MT 81%

Hay, Other 25983 30 81 0.1 0.3 36 95 1.2 1.0 1.2 CA TX KS OR NC 81%

Cotton 13188 145 0 232 2 11 18 770 1224 0.5 1.3 0.4 TX MS LA AR GA 85%

Cropland for Pasture 63687 3 6   4 8 1.3 1.0 1.3 OR CA 80% Site Acres Grown ( 000) Acres Treated ( 000) % of Crop Treated Pounds AI Applied ( 000) Average Application Rate States of Most Usage Wtd Avg Est Max Wtd Avg Est Max Wtd Avg Est Max Pounds ai/ Acre Per Year Pounds Applied Per Year Pounds ai Per Acre Applied (% of total lb ai used on this site)

8 Pasture/ Rangeland, Other 35872 4 26 78 0.01 0.02 62 187 2.4 1.0 2.4 OR 83%

Fallow, Summer 24699 17 52 0.1 0.2 10 29 0.6 1.0 0.6 NE TX 84%

Idle Cropland, Other 7366 4 13 0.1 0.2 9 28 2.1 1.1 1.8 OR 92%

Lots/ Farmsteads/ Etc. 23987 21 37 0.1 0.2 66 134 3.1 1.3 2.4 CA AR WA UT OR NC 70%

Building/ Structures      2 5

Roads/ Ditches/ Misc.      64 129

Ornamentals  47 70   54 80 1.2 1.1 1.1 OR CA MT 87%

Non Farm Industrial Facilities/ Pipelines 4312     518 1047   615

Wholesale/ Manufacturing 30149     166 218

Lawn/ Landscape Operator 30419     46 100   2.0

Residential      13 25

Office/ Retail ( for hire)      28 42

Nurseries/ Greenhouses 409 8 24 2 6 10 29 1.2 1.0 1.2

Office/ Retail ( not for hire)      71 106

Pest Control Operator  5 15

Railroads 1577     2,007 2,907   4.7

Recreation      12 23

Roadways 11400     426 800   2.3

Sanitation/ Utilities      617 1051

Electric Utilities 9669     167 288   3.6

Crops Grown Outside the Continental United States With Limited Usage Data Pineapple no data no data Bananas 14 18 Papaya 13 19 Site Acres Grown ( 000) Acres Treated ( 000) % of Crop Treated Pounds AI Applied ( 000) Average Application Rate States of Most Usage Wtd Avg Est Max Wtd Avg Est Max Wtd Avg Est Max Pounds ai/ Acre Per Year Pounds Applied Per Year Pounds ai Per Acre Applied (% of total lb ai used on this site)

9 Total 7,914 10,429 COLUMN HEADINGS Wtd. Avg. = Weighted average the most recent years and more reliable data are weighted more heavily. Est. Max. = Estimated maximum, which is estimated from available data. Average application rates are calculated from the weighted averages.

NOTES ON TABLE DATA Usage data primarily covers 1990  1999. Calculations of the above numbers may not appear to agree because they are displayed as rounded to the nearest 1,000 for acres treated or lb. a. i. ( therefore 0 = < 500), and rounded to one decimal percentage point for % of crop treated and pounds of a. i.. SOURCES: EPA, USDA , and National Center for Food and Agricultural Policy.

III. Summary of Diuron Risk Assessment The following is a summary of EPA's human health and ecological risk findings and conclusions for diuron, as presented fully in the documents, " Diuron: the Revised HED Chapter of the Reregistration Eligibility Decision Document ( RED)," dated July 9, 2003, " Environmental Risk Assessment for the Reregistration of Diuron," dated August 27, 2001, and " Surface Water Monitoring Data for Diuron," dated August 5, 2003. Since the completion of the preliminary risk assessments, the Agency has calculated new surface water concentrations for diuron based on monitoring data. Also, new information provided by stakeholders enabled the Agency to characterize worker cancer risk estimates.

The purpose of this section of the decision document is to summarize the key features and findings of the risk assessment in order to help the reader better understand the risk management decisions reached by the Agency. While the risk assessments and related addenda are not included in this document, they are available in the public docket.

A. Human Health Risk Assessment Risks from dietary exposure ( food and drinking water), residential exposure, aggregate exposures, and occupational exposures have been evaluated for diuron. 1. Dietary Risk From Food a. Toxicity The toxicity database for diuron is adequate to assess the potential hazard to humans, including special sensitivity of infants and children. The database will support a reregistration eligibility decision for the currently registered uses. However, EPA is requiring that a 28 day inhalation study be submitted to address the concern for inhalation exposure potential based on the use pattern. For more information on the toxicity of diuron, please see the document titled 10 " Diuron  Phase 2: Revised Toxicology Disciplinary Chapter for the Reregistration Eligibility Decision," dated March 6, 2002.

Acute Toxicity:

Diuron has low acute toxicity ( Toxicity Category 3 or 4) by the oral, dermal, or inhalation exposure routes. Diuron is not an eye or skin irritant, and not a skin sensitizer. A rat metabolism study indicated that diuron is rapidly absorbed and metabolized within 24 hours post dose at the low dose and within 48 hours post dose at the high dose. The urine is the major route of excretion in both sexes. A small amount of diuron is detected in the feces. The highest tissue residue levels were found in the liver and kidneys 4 days post 14C diuron dose. The metabolism of diuron involved N oxidation, some ring hydroxylation, demethylation, dechlorination, and conjugation to sulfate and glucuronic acid. Acute toxicity values and categories for the technical grade of diuron are summarized in Table 3.

Table 3. Acute Toxicity of Diuron Guideline No. Study Type Results Toxicity Category 870.1100 Acute Oral LD 50 = 4721 mg/ kg ( M) > 5000 mg/ kg ( F) III 870.1200 Acute Dermal LD 50 > 2000 mg/ kg III 870.1300 Acute Inhalation LC 50 > 7.1 mg/ L IV 870.2400 Primary Eye Irritation At 48 hrs, all irritation had cleared. III 870.2500 Primary Skin Irritation All irritation had cleared by 72 hrs. IV 870.2600 Dermal Sensitization Nonsensitizer N/ A 870.6200 Acute Neurotoxicity Not available N/ A Subchronic/ Chronic Systemic Toxicity: The primary diuron target sites are blood, bladder, and kidney. Erythrocyte ( red blood cell) damage resulted in hemolytic anemia and compensatory hematopoiesis, which are manifested as significantly decreased erythrocyte counts, hemoglobin levels, and hematocrit, and increased mean corpuscular volume ( MCV), mean corpuscular hemoglobin ( MCH), abnormal erythrocyte forms, reticulocyte counts, and leukocyte count. Consistent observations of erythocytic regeneration are seen in chronic toxicity studies in rats, mice and dogs. Gross pathology findings in chronic rat and mouse studies showed increased incidences of urinary bladder swelling and wall thickening at high doses. Microscopic evaluation showed dose related increases in the severity of epithelial focal hyperplasia of the urinary bladder and renal pelvis ( kidney) in both sexes. 11 Although the developmental toxicity study in rats is classified as unacceptable, the data base as a whole is adequate for pre and post natal toxicity evaluation and did not reveal developmental or reproductive toxicity. The NOAELs for maternal/ parental toxicity were either less than or equal to the NOAELs for fetal or reproductive toxicity. A complete summary of the toxicity database is discussed in the document titled " Diuron  Phase 2: Revised Toxicology Disciplinary Chapter for the Reregistration Eligibility Decision," dated March 6, 2002.

Carcinogenicity: Diuron has been characterized as a " known/ likely" human carcinogen, based on urinary bladder carcinomas in both sexes of the Wistar rat, kidney carcinomas in the male rat ( a rare tumor), and mammary gland carcinomas in the female NMRI mouse. The Agency has used a low dose linear extrapolation model with a Q 1 * of 1.91 x 10 2 ( mg/ kg/ day) 1 to be applied to the animal data for the quantification of human risk, based on the urinary bladder carcinomas in the rat. Tumors were observed only at doses in excess of 600 mg/ kg/ day.

Mechanism of Carcinogenicity: The registrant has requested that the Agency reconsider the 1996 carcinogenicity assessment for the following reasons: 1) there is a plausible mode of action that discounts the relevance of the rat bladder carcinomas to humans, 2) the mouse historical data were not considered in their entirety and should be considered ` spontaneous," 3) the structure activity relationships actually decrease the weight of the evidence of diuron carcinogenicity rather than increase the weight, 4) new guidelines are in place that separate the ` known' from ` likely' category and 5) there is no history of human carcinogenesis as a result of diuron exposure.

The Agency reviewed the submitted information/ data and mutagenicity studies, considered the registrant's proposed mechanism of action and determined that diuron will not be re classified at this time. The Agency based its decision on: 1) the registrant did not submit any data or information to support its claim that there is no evidence of human carcinogenesis; 2) the submitted information is insufficient to support a mode of action on bladder carcinogenicity for diuron; 3) the mouse historical data have been reviewed  the Agency concluded that a positive oncogenic response was seen in high dose female mice compared to the control group; 4) there is insufficient evidence to support the notion that the structure activity relationships actually decrease the weight of the evidence of diuron carcinogenicity rather than increase the weight; and 5) preliminary reviews have been conducted on newly submitted in vivo cytogenetic mutagenicity studies ( mouse bone marrow micronucleus assays) and no evidence of cytogenetic effect was seen in mice administered either technical grade or formulated diuron. However, these studies provide little additional information since EPA has already concluded that there is little or no concern for the mutagenic activity of diuron. The registrant has indicated their intention to submit a study on the cancer mechanism of action for diuron. The study is scheduled for completion in 2004 and will be submitted to the Agency for further consideration.

Mutagenicity: Diuron was not mutagenic in bacteria or in cultured mammalian cells and no indication of DNA damage in primary rat hepatocytes was observed. There were marginal statistically significant increases in cells with structural aberrations in a Sprague Dawley rat in vivo bone marrow chromosomal aberration assay. However, the levels of aberrations were within 12 the historical control range and assessed negative.

Developmental/ Reproductive Toxicity: There is an acceptable developmental toxicity study in rabbits and an acceptable two generation reproduction study in rats. A developmental toxicity study in rats was classified as unacceptable due to deficiencies in analytical data on the sample analysis; however, the Agency considered the developmental toxicity study in rats adequate for the FQPA susceptibility assessment based on the observation that the developmental toxicity NOAEL was higher than the maternal NOAEL and concluded that a developmental neurotoxicity ( DNT) study is not required.

There is no indication of increased susceptibility to young exposed to diuron in the available studies. In the developmental toxicity study in rabbits, there were no developmental effects at the highest dose tested. In the developmental toxicity study in rabbits and in the 2 generation rat reproduction study, developmental/ offspring effects were observed only at maternally/ parentally toxic dose levels.

Neurotoxicity: No acute or subchronic neurotoxicity data are available. However, there are no neurotoxic signs in any of the submitted subchronic or chronic studies and a literature search did not reveal any studies relevant for assessing the potential neurotoxicity of diuron.

Dermal Absorption: No systemic toxicity was seen following repeated dermal dosing at 1200 mg/ kg/ day in the rabbit dermal toxicity study. An upper bound estimation of dermal absorption of 4% was extrapolated using the maternal LOAEL of 50 mg/ kg/ day from the oral developmental toxicity study in the rabbit and the NOAEL of 1200 mg/ kg/ day ( HDT) from the 21 day dermal toxicity study in the rabbit: the ratio is 50/ 1200 or 4%.

b. FQPA Safety Factor The FQPA safety factor is intended to provide up to an additional 10 fold safety factor ( 10X), to protect for special sensitivity in infants and children to specific pesticide residues in food. The FQPA Safety Factor Committee concluded that the safety factor could be removed ( i. e., reduced to 1x) for diuron for the following reasons:

° There is no indication of quantitative or qualitative increased susceptibility of rats or rabbits to in utero or postnatal exposure; ° A DNT study with diuron is not required; and ° The dietary ( food and drinking water) and non dietary ( residential) exposure assessments will not underestimate the potential exposures for infants and children.

c. Endpoints and Doses for Risk Assessment The doses, toxicity endpoints selected and supporting studies for various exposure scenarios are summarized in Table 5. 13 Table 5. Summary of Doses and Toxicological Endpoints for Diuron EXPOSURE SCENARIO DOSE ( mg/ kg/ day) ENDPOINT STUDY Acute Dietary No appropriate endpoint attributed to a single dose was identified. Therefore, an acute RfD was not established.

Chronic Dietary LOAEL = 1.0 UF = 300 FQPA SF = 1 Evidence of hemolytic anemia and compensatory hematopoiesis ( significantly decreased erythrocyte counts, hemoglobin levels, and hematocrit, and increased MCV, MCH, abnormal erythrocyte forms, reticulocyte counts, and leukocyte count) Combined chronic toxicity/ carcinogenicity study in rats MRID 40886501, 43871901, 43804501, 44302003 Chronic RfD = 0.003 mg/ kg/ day cPAD = 0.003 mg/ kg/ day Incidental Oral, short term ( 1 30 days) NOAEL= 10 UF = 100 FQPA SF = 1 Decreased body weight and food consumption at maternal LOAEL of 50 mg/ kg/ day. Developmental toxicity study in rabbits MRID 40228802 Level of Concern for residential MOE = 100 Incidental Oral, Intermediate Term ( 1 6 months) NOAEL = 1.0 UF = 100 FQPA SF = 1 Altered hematological parameters at LOAEL of 10 mg/ kg/ day, observed at 6 months. Chronic toxicity/ carcinogenicity study in rats MRID 40886501, 43871901, 43804501, 44302003 Level of Concern for residential MOE = 100 Dermal, Short Intermediate Term No systemic toxicity was seen following repeated dermal dosing at 1200 mg/ kg/ day in the rabbit dermal toxicity study. No hazard was identified and no quantitative assessment is required.

Dermal, Long Term ( 6 months to life time)

Absorption factor of 4% used for conversion from oral to dermal route LOAEL = 1.0 UF = 300 FQPA SF = 1 Evidence of hemolytic anemia and compensatory hematopoiesis ( significantly decreased erythrocyte counts, hemoglobin levels, and hematocrit, and increased MCV, MCH, abnormal erythrocyte forms, reticulocyte counts, and leukocyte count). Chronic toxicity/ carcinogenicity study in rats MRID 40886501, 43871901, 43804501, 44302003 Level of Concern for occupational/ residential MOE = 300 Inhalation, Short Term ( 1 30 days) NOAEL = 10 UF = 100 FQPA SF = 1 Decreased body weight and food consumption at maternal LOAEL of 50 mg/ kg/ day. Developmental toxicity study in rabbits MRID 40228802 Level of Concern for occupational/ residential MOE = 100 EXPOSURE SCENARIO DOSE ( mg/ kg/ day) ENDPOINT STUDY 14 Inhalation, Intermediate Term ( 1 6 months)** NOAEL = 1.0 UF = 100 FQPA SF = 1 Altered hematological parameters at LOAEL of 10 mg/ kg/ day, observed at 6 months. Chronic toxicity/ carcinogenicity study in rats MRID 40886501, 43871901, 43804501, 44302003 Level of Concern for occupational/ residential MOE = 100 Inhalation, Long Term ( 6 months to life time)** LOAEL = 1.0 UF = 300 FQPA SF = 1 Evidence of hemolytic anemia and compensatory hematopoiesis ( significantly decreased erythrocyte counts, hemoglobin levels, and hematocrit, and increased MCV, MCH, abnormal erythrocyte forms, reticulocyte counts, and leukocyte count). Chronic toxicity/ carcinogenicity study in rats MRID 40886501, 43871901, 43804501, 44302003 Level of Concern for occupational/ residential MOE = 300 Cancer Known/ likely human carcinogen Urinary bladder carcinoma in both sexes of the Wistar rat, kidney carcinomas in the male rat ( a rare tumor), and mammary gland carcinomas in the female NMRI mouse Carcinogenicity studies in rats and mice MRID 40886501, 43871901, 43804501, 44302003 and 42159501, 43349301 Q1* = 1.91 x 10 2 ( mg/ kg/ day) 1 UF = Uncertainty Factor PAD = Population Adjusted Dose ( includes UF and FQPA safety factor) MOE = Margin of Exposure d. Endocrine Disruption EPA is required under the FFDCA, as amended by FQPA, to develop a screening program to determine whether certain substances ( including all pesticide active and other ingredients) " may have an effect in humans that is similar to an effect produced by a naturally occurring estrogen, or other such endocrine effects as the Administrator may designate." Following the recommendations of its Endocrine Disruptor Screening and Testing Advisory Committee ( EDSTAC), EPA determined that there was scientific bases for including, as part of the program, the androgen and thyroid hormone systems, in addition to the estrogen hormone system. EPA also adopted EDSTAC's recommendation that the Program include evaluations of potential effects in wildlife. As the science develops and resources allow, screening of additional hormone systems may be added to the Endocrine Disruptor Screening Program ( EDSP). When the appropriate screening and/ or testing protocols being considered under the Agency's EDSP have been developed, diuron may be subjected to additional screening and/ or testing to better characterize effects related to endocrine disruption.

At this time, neither the available submitted studies on diuron nor the literature show any indication of endocrine disruption effects. 15 e. 3,4 dichloroaniline ( 3,4 DCA)

3,4 dichloroaniline ( 3,4 DCA) is a metabolite of diuron as well as two other pesticides, linuron and propanil. However, EPA's Metabolism Assessment Review Committee ( MARC) concluded that residues of 3,4 DCA should not be aggregated for the diuron, linuron, and propanil risk assessments because 3,4 DCA is significant residue of concern for propanil, but is not a residue of concern per se for diuron or linuron. Although the analytical method for quantifying residues of concern from diuron converts all residues to 3,4 DCA as a convenience, 3,4 DCA was not a significant residue in any metabolism or hydrolysis study.

f. Potential Tetrachloroazobenzene Contamination Diuron has been reported to contain trace amounts of a manufacturing impurity, 3,3', 4,4' tetrachloroazobenzene, ( TCAB), which has been shown to be a cytochrome P450 enzyme inducer. A summary of short term bioassays compiled by the National Toxicology Program states that ( TOX 65, 1998),

" 3,3', 4,4' tetrachloroazobenzene caused typical dioxin like effects, such as thymic atrophy, an increase in liver weights, induction of hepatic cytochrome P4501A, and decreased mean body weight gains. Furthermore, in the 13 week studies, a sharp decrease in circulating thyroxine concentrations was observed even at the lowest dose ( 0.1 mg/ kg) tested in rats. Other effects included a decrease in epididymal spermatozoal concentration in mice, major effects on the hematopoietic system, and increased incidence of hyperplasia of the forestomach in 3 and 30 mg/ kg males and 30 mg/ kg females. A no observable adverse effect level ( NOAEL) was not reached in rats. The NOAEL in mice was 0.1 mg/ kg. Comparison of various dioxin like effects in these studies with those reported in the literature indicate that 3,3', 4,4' tetrachloroazobenzene is two to six orders of magnitude less potent than 2,3,7,8 tetrachlorodibenzo p dioxin."

Chronic toxicity/ carcinogenicity studies are not available for TCAB. The specific endpoint( s) and related dose levels that may be observed in chronic toxicity studies, or the specific carcinogenic potential of this compound is not known. However, since it is assumed that TCAB may have been present in all diuron toxicological test materials, including the test material for the chronic toxicity/ carcinogenicity studies, the Agency concludes that the risks from exposure to diuron and TCAB resulting from use of diuron products ( including carcinogenic potential) have not been underestimated.

g. Exposure Assumptions Diuron is not acutely toxic. No adverse effects attributed to a single exposure were identified in any available study. Therefore, no acute dietary risk assessment was conducted. A chronic exposure analysis for diuron and its metabolites that are hydrolyzable to 3,4 DCA was performed utilizing the Dietary Exposure Evaluation Model ( DEEMTM) software Version 7.73. 16 DEEMTM, developed by Novigen Sciences, Inc. This model calculates acute and chronic dietary exposure and risk estimates for residues in food for the U. S. general population and various population subgroups. The software contains food consumption data from the USDA Continuing Survey of Food Intake by Individuals ( CFSII) from 1989 1992. For chronic and cancer dietary risk assessments, the 1989 1992 data are based on the reported consumption patterns of more than 10,000 individuals over three consecutive days, and therefore represent more than 30,000 unique " person days" of data. Foods " as consumed" ( e. g. apple pie) are linked to raw agricultural commodities and their food forms ( e. g. apples cooked/ canned or wheat flour) by proprietary recipe translation files within DEEM. Consumption data are averaged for the entire U. S. population and within population subgroups for chronic exposure assessment. For chronic exposure and risk assessment, an estimate of the residue level in each food or food form ( e. g. orange or orange juice) on the commodity residue list is multiplied by the average daily consumption estimate for that food/ food form. The resulting residue consumption estimate for each food/ food form is summed with the residue consumption estimates for all other food/ food forms on the commodity residue list to arrive at the total estimated exposure. The calculated chronic exposure ( residue x consumption) was compared to a cPAD of 0.003 mg/ kg/ day, which reflects an FQPA factor of 1x. Noncancer dietary exposure estimates are expressed in milligrams per kilogram of body weight per day ( mg/ kg/ day).

Diuron is used on a wide variety of food and feed crops. Residue levels from United States Department of Agriculture ( USDA) and Food and Drug Administration ( FDA) monitoring programs do not include all the residues of concern needed for the Agency's diuron risk assessment ( diuron and metabolites convertible to 3,4 DCA) and were not used for this analysis. Instead, anticipated residues ( ARs) from field trial data were utilized to estimate the dietary exposure to diuron from the diets of the U. S. population as well as certain population subgroups. The field trials were conducted at the highest application rates for the crop tested and therefore, the residues from these trials are considered high end.

Available processing data for apple, citrus and grapes indicated that there was no concentration, nor reduction, in residue values for these processed commodities ( i. e., juice, dried fruit). The sugarcane processing study showed a reduction of residues in refined sugar but a concentration of residues in molasses. With the exception of residue data from the processing of sugarcane into refined sugar and molasses, the only additional refinements to the residue data are the use of averaged percent crop treated (% CT) information. Percent crop treated data were available for blackberries, blueberries, raspberries, grapes, grapefruit, lemons, oranges, limes, tangelos, tangerines, temples, apples, pears, avocados, sweet cherries, tart cherries, nectarines, olives peaches, plums/ prunes, almonds, hazelnuts, macadamia nuts, pistachio nuts, pecans, walnuts, asparagus, barley corn, mint oats, seed crops, sorghum, sugarcane, wheat, alfalfa, hay, cotton, cropland for pasture, pasture/ rangeland, fallow, idle cropland, lots/ farmsteads, and nurseries/ greenhouses. These data were used for the chronic dietary assessment.

The reregistration requirements for magnitude of the residue in plants are not fulfilled for: alfalfa forage; globe artichoke; barley hay; cotton gin byproducts; field corn aspirated grain 17 fractions; field corn forage and stover; filbert; grass forage, hay, seed screenings, and straw; lemon; pear; oat forage, hay; olive; field pea vines and hay; sorghum aspirated grain fractions, stover, and forage; wheat forage and hay. Additional crop field trial data are required for these commodities.

h. Dietary ( Food) Risk Assessment ( 1) Acute Dietary Risk There are no adverse effects attributed to a single exposure identified in any available studies. In addition, diuron has low acute toxicity and no developmental or neurotoxic concerns. Therefore, no acute dietary endpoint was chosen and no acute dietary risk assessment was conducted.

( 2) Chronic ( Non Cancer) Dietary Risk Chronic dietary risk is calculated by using an average consumption value for food and average residue values on those foods consumed over a 70 year lifetime. A risk estimate that is less than 100% of the chronic PAD ( the dose at which an individual could be exposed over the course of a lifetime and no adverse health effects would be expected) does not exceed the Agency's level of concern. The cPAD is the chronic reference dose ( cRfD) adjusted for the FQPA Safety Factor.

As shown in Table 6, non cancer chronic risk estimates for all population subgroups are below the Agency's level of concern (< 100% cPAD). Estimated chronic dietary ( food) risk estimates associated with the use of diuron do not exceed the Agency's level of concern (> 100% cPAD) for any population subgroup including the most highly exposed population subgroup, children ages 1 6 years. The chronic dietary risk for children ages 1 6 years is 7% of the chronic PAD and 3% for the general U. S. population. Orange juice and orange juice concentrate are the largest contributors to dietary exposure from diuron. 18 Table 6. Summary of Chronic Dietary Exposure and Risk for Diuron Population Exposure mg/ kg/ day % Chronic PAD U. S. Population 0.000088 3 All Infants (< 1 year) 0.000077 3 Children 1 6 years 0.00020 7 Children 7 12 years 0.000118 4 Females 13 50 years 0.000069 2 Males 13 19 years 0.000098 3 Males 20+ years 0.000066 2 Seniors 55+ years 0.000083 3 ( 3) Cancer Dietary Risk from Food Like chronic dietary risk, potential dietary cancer risk is calculated by using the average consumption values for food and average residue values for those foods over a 70 year lifetime. The chronic exposure value is typically combined with a linear low dose ( Q 1*) approach to determine the lifetime ( cancer) risk estimate. The Agency generally considers risks greater than 1 x 10 6 ( i. e., probability greater than one in one million) to be of potential concern for dietary cancer exposure. Table 7 presents the lifetime ( 70 year) cancer risk estimates for the U. S. general population. The estimated cancer dietary risk associated with the use of diuron indicates a borderline exceedance above 1 x 10 6 and shows a lifetime risk estimate of 1.68 x 10 6 for the general population but, is not of concern. As discussed earlier, the residues used in the calculations are from field trials conducted at the highest application rates and some processing data are still outstanding. Therefore, the exposure calculation is a conservative estimate. Again, the Agency assumed that exposure was to diuron and its metabolites that are hydrolyzable to 3,4 DCA. 19 Table 7 . Summary of Diuron Dietary Exposure and Risk Population Acute Dietary Chronic Dietary Cancer Dietary NA Exposure ( mg/ kg/ day) Risk (% cPAD) Exposure ( mg/ kg/ day) Lifetime Risk ( Q1*= 0.0191)

U. S. Population 0.000088 3 0.000088 1.68 x 10 6 All Infants < 1 year 0.000077 3 Not Applicable Children 1 6 years 0.000200 7 Children 7 12 years 0.000118 4 Females 13 50 years 0.000069 2 MCPDMU Cancer Dietary Risk Environmental laboratory studies have shown that in drinking water only, diuron partially degrades to another chemical referred to as MCPDMU ( N'( 3 chlorophenyl) N, N dimethyl urea). However, the environmental fate and persistence of MCPDMU are uncertain. MCPDMU is structurally similar to monuron [ N'( 4 chlorophenyl) N, N dimethyl urea], a pesticide no longer registered in the United States. Monuron produces tumors in the kidney and liver in male rats and has a Q 1* of 1.52 x 10 2. Due to the structural similarity between MCPDMU and monuron, the Agency believes it is prudent to evaluate the carcinogenic risk associated with MCPDMU based upon the hazard information concerning the chemical monuron. The Agency believes MCPDMU is likely less toxic than monuron, but is unable to quantify this difference without further information. The approach used in this assessment yields a high end estimate. Absent information specifically about the carcinorgenic potential of MCPDMU, the Agency has taken this conservative, health protective approach in its assessment. The Agency is addressing this uncertainty by requiring additional information about the behavior and fate of diuron and its drinking water degradate, MCPDMU.

Two separate cancer risk assessments were completed for diuron and MCPDMU ( N'( 3 chlorophenyl) N, N dimethyl urea), a degradate of diuron in water only. Because the cancer effects ( i. e., target organs) for the two compounds differ, the risks from diuron and MCPDMU are not combined.

Based on a Q 1* of a similar compound, monuron, the estimated dietary risk for MCPDMU is 1.02 x 10 7, which includes catfish consumption only. The anticipated residue of MCPDMU in catfish was calculated using the 2 ppm tolerance for catfish, the fraction of applied radioactive diuron converted to MCPDMU in an aerobic aquatic metabolism study ( see the Environmental Risk Assessment) and the percent crop treated for catfish.

2. Dietary Risk from Drinking Water 20 Drinking water exposure to pesticides can occur through ground and surface water contamination. EPA considers acute ( one day) and chronic ( lifetime) drinking water risks and uses either modeling or actual monitoring data, if available, to estimate those risks. For diuron, monitoring data were available for states with a high percent of diuron use. Therefore, monitoring data from Florida and California were used to estimate surface water concentrations, and SCI GROW was used to estimate groundwater concentrations. The Screening Concentration in Ground Water Program ( SCI GROW), model is considered a screening tool.

To determine the maximum allowable contribution of pesticide residue in water allowed in the diet, EPA first looks at how much of the overall allowable risk is contributed by food, then calculates a drinking water level of comparison ( DWLOC) to determine whether modeled or monitoring levels exceed this level.

The DWLOC represents the maximum contribution to the human diet ( in ppb or µ g/ L) that may be attributed to residues of a pesticide in drinking water after dietary exposure is subtracted from the aPAD or cPAD. Risks from drinking water are assessed by comparing the DWLOCs to the estimated environmental concentrations ( EECs) in surface water and ground water. Drinking water modeling is considered to be an unrefined assessment and provides conservative estimates based on maximum labeled rates and number of applications.

Neither diuron nor monuron are regulated under the Safe Drinking Water Act. As a result, neither Maximum Contaminant Levels ( MCLs) nor drinking water health advisories ( HAs) for these chemicals have been established by the EPA Office of Water. However, diuron was placed on a list of contaminants to be monitored during 2001 and 2002. This information will be used to support EPA decisions concerning whether or not to regulate and establish standards for diuron in drinking water.

a. Surface Water In this case, only chronic ( non cancer) and cancer drinking water risks have been assessed since no acute endpoint was identified.

Diuron can be transported to surface water at application via run off and spray drift from aerial and ground applications. In the preliminary assessment for surface water, chronic and cancer drinking water risks were potentially of concern based on modeled estimates. Based on information gathered after the initial risk assessment was prepared, the Agency has decided to use surface water monitoring data to estimate risks from drinking water. Conservative models were used to determine that the diuron degradates would add an additional 20 percent to the concentration of the parent compound. The drinking water assessment includes surface water monitoring data from Florida, the scenario which is anticipated to represent the highest potential drinking water concern. The following information was used in the revised surface water assessment. 21  South Florida Surface Water Monitoring Data Data collected by the South Florida Water Management District ( SFWMD) between December, 1998 and August, 2001 indicate that diuron was detected in only 17 of 438 samples ( 4% detection rate). The 37 monitoring stations were in south Florida, from Lake Okeechobee south to the Everglades. Diuron is used on citrus, bananas, and sugarcane in this area. The highest reported concentration was 1.2 ppb. The 90th and 95th percentile concentrations were below the detection limit ( 0.2 to 0.4 ppb). The data are available at www. sfwmd. gov/ curre/ pest/ pestindex. htm.

 US Geological Survey ( USGS) National Water Quality Assessment Program ( NAWQA) data for Southeastern U. S.

USGS NAWQA data for 3 study units ( South Florida, Georgia Florida Coastal Plain, and Appalachicola Chattahoochee Flint River) show a 22% detection rate ( 185 of 858 samples) for diuron over the period 1993 to 1998. Most of the latter study area was around Atlanta. All detects were less than or equal to 1 ppb. The median, 90th percentile, and 95th percentile concentrations were 0.05 ppb. The 99th percentile was approximately 0.3 ppb. The detection limit was 0.02 ppb, about ten times lower than SFWMD's detection limit of 0.2 to 0.4 ppb, which may explain the higher detection rate.

 NAWQA Data The USGS NAWQA Program collected 1420 surface water samples from 62 agricultural stream sites during a 6 year period from 1992  1998. Diuron was detected in 7.32% of the samples at a mean concentration of 0.13 ppb.

 California Dormant Spray Monitoring Study The California Department of Pesticide Regulation ( DFR) conducted a Dormant Spray Monitoring Study at three locations ( 82 samples) in the Sacramento River and two locations ( 54 samples) in the San Joaquin River, over the period December 2000 to March 2001. About one million pounds of diuron are used in these two watersheds per year. Diuron is used on a number of crops in California, including alfalfa, oranges, grapes, walnuts, asparagus, lemons, olives, cotton, grapefruit, and tangerines. Non agricultural uses include rights of way, landscape maintenance, and uncultivated areas.

Each of the five locations was sampled at least once a week. 100% of the samples on the San Joaquin River had detectable diuron, with a maximum concentration of 8.45 ppb in the Orestimba Creek tributary. The average concentration at the two San Joaquin River stations was 22 1.7 ppb. About 75% of the samples in the Sacramento River had detectable diuron. The maximum concentration was 1.42 ppb at the Alamar Marina dock, 9 miles downstream of the confluence of the Feather River. The average concentration, assuming that all non detects were equal to the detection limit of 0.05 ppb, was 0.16 ppb.

 California DFR Summary, July 8, 2003 California DFR has provided EPA with a summary of historical surface water monitoring data in their SURF database through July, 2000. The total amount of diuron used in California from 1990 to 1998 was just over ten million pounds. Diuron was the most frequently detected ( 57.2% or 350 of 612 samples) of the 146 chemicals in the SURF database. The median concentration was 0.281 ppb, the 75th percentile was 0.719 ppb, and the 95th percentile was 3.6 ppb.

 Texas Playa Lakes Study A study on the occurrence of cotton herbicides and insecticides in the Playa Lakes area of the high plains of western Texas was evaluated. Diuron and metabolites were found in 71% of the samples collected from 32 lakes at a mean concentration of 2.7 ppb. This study did not have sufficient frequency of sampling or a long enough sampling period to be used for regulatory purposes. In addition, the study has limited use in a National assessment because western Texas is not expected to be one of the most vulnerable use areas for runoff, the method of contamination expected with diuron. However, because samples were taken within 2 days of application, the results provide an indication of concentrations that could occur in drinking water in that area.

b. Ground Water In the absence of monitoring data, the Screening Concentration in Ground Water ( SCIGROW model, which is a Tier I assessment, was used to estimate potential ground water concentrations. SCI GROW estimates likely groundwater concentrations if the pesticide is used at the maximum allowable rate in areas where groundwater is exceptionally vulnerable to contamination. This assessment represents a conservative estimate and in most cases, a large majority of the use area will have groundwater that is less vulnerable to contamination than the areas used to derive the SCIGROW estimate. Application of diuron to citrus in Florida was modeled. These scenarios represent high application rates and areas vulnerable to ground water contamination. The modeled estimates indicate that ground water concentrations of diuron and its metabolites are below the chronic DWLOC.

For more information on drinking water risks and the DWLOC calculations, see the Water Exposure section of the July 9, 2003, Human Health Risk Assessment, the March 11, 2002 memorandum entitled, " Drinking Water Reassessment for Diuron and its Degradates" and the August 5, 2003 memorandum entitled, " Surface Water Monitoring Data for Diuron." 23 c. Drinking Water Risk Estimates To determine the maximum allowable contribution of pesticide residues in water, EPA first looks at how much of the overall allowable risk is contributed by food and then determines a " drinking water level of comparison" ( DWLOC) to determine whether modeled or monitoring levels exceed this level. The Agency uses the DWLOC as a surrogate to capture risk associated with exposure from pesticides in drinking water. The DWLOC is the maximum concentration in drinking water which, when considered together with dietary exposure, does not exceed a level of concern.

The results of the Agency's drinking water analysis are summarized in Table 8. Details of the drinking water analysis are found in the Human Health Risk Assessment for Diuron, dated September 8, 2003.

Table 8. Estimated Environmental Concentrations and Chronic DWLOCs for Diuron and its Degradates Estimated Environmental Concentrations in Surface and Ground Water for Diuron and its Degradates from Diuron Use on Citrus Estimated Environmental Concentrations (

g/ L)

Diuron MCPDMU DWLOC4 Surface Water Monitoring Data < 11,2 < 11,3 28 Groundwater ( peak and longterm average) 9.12 0.593 1 Increased 20% to account for degradates, as indicated by modeling work. 2 Includes modeled values for the following degradates: DCPMU; DCPU; and 3,4 DCA. 3 Based on modeling, using 6.4 lbs ai/ A application rate for citrus. 4 For the most sensitive subpopulation, children 1  6 years.

Cancer Drinking Water Risk For diuron potential cancer risk, no DWLOC has been calculated. Food alone shows a slight exceedance for cancer risk ( 1.68 x 10 6) based on field trial data using maximum application rates. These estimates can be refined with additional residue and processing data. To better characterize both potential cancer risks from surface water, EPA has used monitoring data from Florida, an area of high diuron use, and other states. These data indicate detections generally one to two orders of magnitude lower than modeled estimates for diuron ( parent compound). Based on this new data, the Agency has concluded that cancer risk from diuron in drinking water is not a concern. The monitoring data for Florida can be found on the following website: www. sfwmd. gov/ curre/ pest/ pestindex. htm. For more information on cancer risks from drinking 24 water, please see the Aggregate Risk Section below. MCPDMU Risk For the degradate MCPDMU, the Agency calculated the EEC using drinking water monitoring data. The monitoring data indicates the EEC for diuron is < 1 ppb, including all of the degradates. Although the water monitoring data do not include data on the degradates of diuron, the Agency has increased the EECs by 20 percent, as indicated by conservative modeling, to account for the degradates. The < 1ppb calculation includes the estimation for the degradates. The < 1 ppb EEC for MCPDMU is below the cancer DWLOC and is not of concern. In addition, environmental fate data are required to confirm estimates of the concentrations and persistence of MCPDMU in water.

As a comparison, the Agency used modeling to calculate the EECs with the revised maximum application rate ( 6.4 lb ai/ A) for citrus. The modeled EEC for MCPDMU is 6.94 ppb, consistent with the monitoring results.

3. Diuron: Residential Exposure and Risk There are two potential sources of exposure to diuron in a residential setting  as an algaecide in ponds and aquariums, and as a preservative or a mildewcide in paints. Exposure from the dermal and inhalation routes are combined for each residential use.

a. Toxicity Table 9 details the results of the hazard assessment for the non dietary risk assessment for diuron. 25 Table 9. Toxicity Endpoints Selected for Assessing Residential Risks for Diuron Route / Duration NOAEL ( mg/ kg/ day) Effect Study Uncertainty Factors and Safety Factors Short term Incidental Oral ( 1 to 30 days) 10 Decreased body weight and food consumption Developmental toxicity study in rabbits Interspecies: 10x Intraspecies: 10x FQPA: 1x Intermediateterm Incidental Oral ( one month to six months) 1.0 Altered hematological parameters observed at six months. Chronic toxicity/ carcinogenicity study in rats Interspecies: 10x Intraspecies: 10x FQPA: 1x Short and intermediateterm Dermal No systemic toxicity following repeated dermal dosing at 1200 mg/ kg/ day was seen in the dermal toxicity study. Also, there is no developmental concern. No hazard was identified and no quantitative assessment is required.

Long term Dermala ( greater than six months) 1.0 ( LOAEL) Evidence of hemolytic anemia and compensatory hematopoiesis. Chronic toxicity/ carcinogenicity study in rats Interspecies: 10x Intraspecies: 10x FQPA: 1x Use of LOAEL instead of a NOAEL: 3x Short term Inhalationb 10 Decreased body weight and food consumption Developmental toxicity study in rabbits Interspecies: 10x Intraspecies: 10x FQPA: 1x Intermediateterm Inhalationb 1.0 Altered hematological parameters observed at six months Chronic toxicity/ carcinogenicity study in rats Interspecies: 10x Intraspecies: 10x FQPA: 1x Long term Inhalationb 1.0 ( LOAEL) Evidence of hemolytic anemia and compensatory hematopoiesis Chronic toxicity/ carcinogenicity study in rats Interspecies: 10x Intraspecies: 10x FQPA: 1x Use of a LOAEL instead of a NOAEL: 3x Cancer Known/ likely human carcinogen Q1* = 1.91 x 10 2 Urinary bladder carcinoma in both sexes of the Wistar rat, kidney carcinomas in the male rat ( a rare tumor), and mammary gland carcinomas in the female NMRI mouse Carcinogenicity study in rats and mice a An oral endpoint was used for dermal exposure: dermal absorption factor of 4% of oral exposure shall be used. b An oral endpoint was used for inhalation exposure: inhalation exposure assumed equivalent to oral exposure.

Similar to dietary cancer risk, potential residential cancer risk is calculated by using the average exposure over a 70 year lifetime. The lifetime exposure value is typically combined with a linear low dose ( Q 1*) approach to determine the lifetime ( cancer) risk estimate. 26 b. Residential Handler Risk ( 1) Exposure Scenarios, Data, & Assumptions There are potential residential exposures from activities associated with pond and aquarium use and paint and stain use. Though there are existing labels for applications of granular formulations of diuron to turf, most are limited to industrial and non crop uses. Others products are either pending cancellation by the registrant or the registrant has agreed to place language specifically eliminating residential uses on the label. Since residential turf uses are being canceled for diuron, a residential assessment for turf was not conducted.

The algaecide products are formulated as tablets/ blocks and as a liquid. There are no exposure data for the use of the algaecide tablets/ blocks. Since the products are formulated as tablets/ blocks and dissolve in less than 5 minutes, minimal exposure is expected and was not quantified. The liquid is used at a rate of one teaspoon ( 5 ml) for every 10 gallons of aquarium or pond water, once a month or when algae growth reappears. Residential exposure may result from measuring the liquid and pouring the liquid into the aquarium or pond. Exposure is expected to be short term ( 1 to 30 days). These risks are not of concern. For more information, see " Diuron: the Revised HED Chapter of the Reregistration Eligibility Decision Document ( RED)," dated September 8, 2003.

Residential painters using paints and stains were assumed to use airless sprayers and paint brushes. Exposure is expected to be short term ( 1 to 30 days). For homeowners, the airless sprayer is assumed to be used for outdoor applications only. For indoor applications, EPA assumed that painting would be restricted to small rooms such as bathrooms ( high potential for moisture) where an airless sprayer is unlikely to be used. These risks are not of concern. The following three residential handler scenarios were evaluated:

( 1) Loading ready to use liquids;

( 2) Applying paints or stains with a paintbrush; and ( 3) Applying paints with an airless sprayer.

The following assumptions were used in the non cancer exposure calculations:

° Average body weight of an adult handler is 70 kg.

° The average residential aquarium is assumed to be 50 gallons and the average residential pond is assumed to be 1,000 gallons. The No More Algae liquid label also states that the maximum residential pond that can be treated is 3,000 gallons, so this volume was assessed as a high end, maximum exposure value. 27 ° The amount of paint used per day for residential handlers is 15 gallons for airless sprayer, two gallons for paintbrush applying paint and five gallons for paintbrush applying stain. For homeowners, the airless sprayer is assumed to be used for outdoor applications only. Homeowner use of diuron treated paint indoors is restricted to small rooms such as bathrooms, laundry rooms, etc. where the use of an airless sprayer is unlikely to occur.

° In addition to diuron's mildewcide use in paints and stains, it is also used in plaster, stuccos, sealants, caulking, and fillers. Unit exposure data only exists for the use of paints/ stains with airless sprayer and paintbrush. These exposure scenarios are assumed to have a higher exposure than use of diuron in plaster, stucco, sealants, caulking and fillers, since less material would be applied in a day. Therefore, the paint/ stain assessment will also be considered an estimate of the exposure resulting from the use of diuron in plaster, stucco, sealants, caulking, and fillers.

° Application rates  The concentration of diuron in the paint, caulking, and other products is 0.2 to 2.5 percent. The maximum amount of diuron per gallon of paint is 0.0532 lbs ai/ gallon paint.

° Exposure frequency  The secondary residential handlers are expected to be of a short term duration ( less than 30 days).

The following assumptions and factors were used in addition to previously stated residential non cancer handler assumptions in order to complete this cancer risk assessment:

° The average lifetime is assumed to be 70 years.

° Exposure duration is assumed to be 50 years. . ° The number of exposures per year for the pond and aquarium uses are based on the label recommendations. The " No More Algae" liquid label states that " For regular maintenance, use once a month or as algae starts to reappear." Therefore, 12 exposures per year were assumed.

° Homeowners applying diuron treated paint are exposed two days per year. Since it would be unusual for homeowners to paint their houses every year with diuron treated paint, this is considered to be a high end estimate.

° Homeowners are assumed to be wearing short sleeved shirt and short pants and no personal protective equipment ( PPE).

No chemical specific handler exposure data have been submitted to determine the extent 28 of these exposures. Secondary residential handlers are assessed using an airless sprayer and a paint brush. The Pesticide Handler Exposure Database ( PHED) was used to estimate homeowner exposure while using diuron treated paint. For comparative purposes, the Agency calculated homeowner exposure to diuron while using a paint brush and an airless sprayer using data submitted for another pesticide. These calculations indicate risks similar to those that were derived from using the PHED.

Although there is potential exposure during the application of the other treated materials ( caulks and sealants), they are not included in this assessment because no data are available to assess these uses. There is also a potential for exposure from applying paint with a roller. However, it is the Agency's conclusion that the airless sprayer and paintbrush scenarios represent the high end exposures for diuron antimicrobial secondary handler uses.

( 2) Residential Handler Risk Characterization Summary of Non Cancer Risk Concerns for Residential Handlers The short term inhalation NOAEL of 10 mg/ kg/ day was used for all non cancer exposures and had a target MOE of 100. The calculations of short term inhalation risk from exposure to the liquid formulation of diuron indicate that inhalation MOEs are more than 100 for the all the assessed exposure scenarios and are not considered risks of concern. Although no data are available to assess exposures and risks from the block/ tablet form of diuron, exposure from the block/ tablet forms of diuron are expected to be less than exposure from the liquid formulation, and therefore are not a risk of concern. For more information, see " Diuron: the Revised HED Chapter of the Reregistration Eligibility Decision Document ( RED)," dated September 8, 2003.

Residential Cancer Risk Characterization The applicator assessment for paints and stains applied with a brush or an airless sprayer is based on a Q 1* of 1.91 x 10 2 ( mg/ kg/ day) 1, and an application rate of 0.053 lb ai per gallon. This is the maximum application rate. For a cancer risk assessment, typical rates would ordinarily be used but these were not available. The assessment also assumes two gallons for paints to five gallons for stains applied with a brush per day or fifteen gallons applied per day with an airless sprayer, 2 applications per year, 50 years of use over a 70 year lifetime, and a high end dermal absorption factor of 4%. Usage information gathered subsequent to the risk assessment indicates that less than 1% of all paint contains diuron. Therefore, it is unlikely that a homeowner would only apply paint containing diuron two times per year for 50 years. The diuron cancer risk estimates are presented in Table 10 below.

Table 10. Diuron Cancer Exposure and Risk Estimates for Homeowner Pond/ Aquarium, Paint and Stain Application 29 Exposure Scenario ( Scenario #) Use site Application Rate Amount Treated Total Daily Dosea Baseline Daily LADDb, c Baseline Riskd Mixer/ Loader ( 12 days/ year)

( 1) Loading Ready to Use Liquids pond 0.0000074 lb ai per gallon 3000 Gallons per day 0.000037 8.7 E 7 1.7 E 8 pond 0.0000074 lb ai per gallon 1000 Gallons per day 0.000012 2.9 E 7 5.5 E 9 aquarium 0.0000074 lb ai per gallon 50 Gallons per day 0.00000062 1.5 E 8 3.0 E 10 Applicator ( 2 days/ year)

( 2) Applying Paint/ Stains with Paintbrush Paint 0.0532 lb ai per gallon 2 Gallons per day 0.014 5.5 E 5 1.1 E 6 Stains 0.0532 lb ai per gallon 5 Gallons per day 0.036 1.4 E 4 2.7 E 6 ( 3) Applying Paint with Airless Sprayer Paint 0.0532 lb ai per gallon 15 Gallons per day 0.045 1.8 E 4 3.4 E 6 a Total Daily Dose ( mg/ kg/ day) = Daily Dermal Dose ( mg/ kg/ day) * Dermal Absorption ( 4%) + Daily Inhalation Dose ( mg/ kg/ day). See Table 13 for daily dermal and inhalation doses. b The number of exposures per year are based on the label recommendations. The No More Algae Liquid label states that " For regular maintenance, use once a month or as algae starts to reappear." Therefore, 12 exposures per year were assumed. Two exposure per year assumed for residential person painting their home. c Lifetime average daily dose ( LADD) ( mg/ kg/ day) = Total Daily Dose ( mg/ kg/ day) * ( number of days of exposure per year / 365 days/ year) * ( 50 years exposed / 70 years in a lifetime). d Cancer risk = LADD ( mg/ kg/ day) * Q1 ( 1.91E 2 mg/ kg/ day).

c. Residential Postapplication Risk Characterization ( 1) Exposure Scenarios, Data, & Assumptions Residential postapplication inhalation and dermal exposure is expected to occur from the use of diuron in ponds and aquariums and from the indoor use of paints and stains. The following residential postapplication scenarios were evaluated:

( 1) Inhalation exposure from diuron use in ponds and aquariums;

( 2) Dermal exposure from diuron use in ponds and aquariums;

( 3) Inhalation exposure from the indoor use of diuron paints or stains; and ( 4) Dermal exposure from the indoor use of diuron paints or stains.

Note that postapplication exposure to turf is no longer considered in the residential postapplication risk assessment. The registrants have agreed to prohibit turf treatment in residential areas. 30 The following assumptions were used:

° Typical homeowner clothing indoors is represented by short pants, short sleeve shirt, no gloves.

° The average body weight of 70 kg was used.

° Diuron products applied to ponds or aquariums is in tablet/ block or a ready to use liquid form.

° Two tablet products were assessed, one product that requires using one tablet for every 10 gallons of aquarium or pond water and one product that requires using one tablet for every 250 gallons of pond water.

° Short term exposure of one to 30 days for pond/ aquarium treatment and for paint/ stain use.

( 2) Residential Postapplication Risk Characterization Postapplication inhalation and dermal exposure resulting from the use of diuron in ponds and aquariums is expected to be minimal and not of concern. Diuron is applied to ponds/ aquariums in the form of a liquid and an effervescent tablet. Due to the high dilution rate of the liquid in pond and aquarium water ( 0.0000074 lb ai per gallon of water), and the effervescent nature of the tablet ( expected to dissolve in less than five minutes), postapplication exposure to diuron in pond and aquarium water is expected to be minimal. Furthermore, postapplication activities in and around ponds/ aquariums treated with diuron are assumed to be infrequent.

Postapplication inhalation and dermal exposure resulting from the indoor use of diuron in paints is also expected to be minimal and not of concern. HED has conducted a screening level inhalation assessment using the Multi Chamber Concentration and Exposure Model ( MCCEM). MCCEM uses air infiltration and interzonal air flow rates, together with user inputs for emission rates, decay rates, and outdoor concentrations to calculate time varying indoor concentrations and associated indoor inhalation exposure due to product or material emissions in several zones or chambers within a residence. The results of this model, coupled with diuron's low vapor pressure ( 2 x 10 7 mm Hg at 30

C), show minimal postapplication inhalation exposure. Furthermore, diuron treated paint is only likely to be used in rooms where high humidity is expected ( i. e. a bathroom), and would rarely be used in the entire house. It is unlikely that a homeowner would receive a significant amount of postapplication inhalation exposure from diuron treated paint, as the very nature of its use is as a mildewcide, and any substantial loss of the active ingredient from the paint would render the product ineffective.

4. Aggregate Risk 31 The Food Quality Protection Act amendments to the Federal Food, Drug, and Cosmetic Act ( FFDCA, Section 408( b)( 2)( A)( ii)) require " that there is reasonable certainty that no harm will result from aggregate exposure to pesticide chemical residue, including all anticipated dietary exposures and other exposures for which there are reliable information." Aggregate exposure will typically include exposures from food, drinking water, residential uses of a pesticide, and other non occupational sources of exposure. For diuron, aggregate risk assessments were conducted for short term ( one to thirty days), and chronic ( several months to lifetime) exposures. The aggregate risk assessments for chronic exposures include a non cancer and a cancer risk assessment. No acute or intermediate term aggregate risks were assessed because there was no systemic toxicity seen in the acute oral or 21 day dermal toxicity study.

a. Acute Aggregate Risk No adverse effects attributed to a single exposure to diuron were identified in any available studies. Therefore, no acute dietary risk assessment was warranted.

b. Short Term Aggregate Risk When potential food and residential inhalation exposures are combined they result in aggregate short term MOEs of 1043 and 1045 for adult males and females, respectively, which are not of concern. Based on labeled uses, no intermediate or long term residential handler, or substantial postapplication exposures of any duration, are expected.

Aggregate short term risk estimates for diuron and its metabolites hydrolyzable to 3,4 DCA would combine exposures from food ( average), water, and residential inhalation only. Estimates of allowable levels of diuron in drinking water were calculated using DWLOCs. The Agency determined that it was unlikely that more than one of the residential handler activities would occur concurrently during a short term time period. Therefore, the Agency took the protective approach of including the exposures from the activity which could potentially result in the most exposure to the homeowner, applying paint with an airless sprayer, in the aggregate assessment. As noted previously, residential exposures are calculated using short sleeved shirt and short pants ( no personal protective equipment, no engineering controls).

An MOE was calculated to estimate the short term aggregate risk, combining food and inhalation exposures, and using a NOAEL of 10 mg/ kg/ day. A UF of 100 ( 10x for interspecies extrapolation, 10x for intraspecies variability) and the 1x FQPA safety factor for diuron were applied to the assessment; therefore, an MOE of greater than 100 is not of concern. As shown in Table 11, the surface water and groundwater EECs are below the DWLOCs and are not of concern. Table 11. Diuron Aggregate DWLOCs for Short Term Exposures 32 Population Subgroup1 Aggregate Risk MOE 2 ( food and residential) Surface Water EEC 3 ( ppb) Ground Water EEC 3 ( ppb) Short Term DWLOC 4 ( ppb)

Adult Males 1043 104 9.1 3153 Adult Females 1045 2700 1 Only adults are included in aggregate risk assessment; it is assumed that only adults will apply paint 2 Aggregate MOE = [ NOAEL ÷ ( Avg Food Exposure + Residential Exposure)] 3 The crop producing the highest level was used to assess exposure to diuron, DCPMU, DCPU, 3,4 DCA, total. 4DWLOC(

g/ L) = [ maximum water exposure ( mg/ kg/ day) x body weight ( kg)] [ water consumption ( L) x 10 3 mg/

g]

c. Chronic ( Non Cancer) Aggregate Risk Aggregate chronic ( noncancer) risk estimates include the contribution of exposure from dietary sources ( food + water) and residential sources. However, based on the labeled uses, no long term or chronic residential exposures are expected. Chronic risk estimates from exposures to food, associated with the use of diuron do not exceed the Agency's level of concern for the most highly exposed population subgroup, children ages 1 6 years of age. The chronic dietary ( food only) risk estimate for children ages 1 6 years of age was < 7% of the chronic PAD.

The original Tier 2 drinking water assessment was based on the PRZM/ EXAMS model and identified chronic drinking water concerns. Since that time, the registrant has submitted an analysis of surface water supplies identified using Geographic Information Systems information from Florida, coupled with water monitoring data. The submitted data, combined with additional monitoring data that was subsequently identified, was reviewed and determined to have enough samples and be of sufficient quality to allow the Agency to refine the drinking water analysis. The revised chronic EEC is < 1 ppb. Conservative models were used to determine that the diuron degradates would add an additional 20 percent to the concentration of the parent compound. The < 1 ppb estimation includes the estimation for the degradates. Based on this new data, the Agency has concluded that chronic risk of diuron in drinking water is not a concern. For more information, please see the document titled " Environmental Risk Assessment for the Reregistration of Diuron," dated August 27, 2001. Table 12 presents the DWLOCs for various subpopulations. 33 Table 12 . DWLOCs for Chronic Non Cancer Aggregate Dietary Exposure Population Subgroup Surface Water EECs ( ppb) Chronic DWLOC ( ppb)

Non Cancer U. S. Population 1 102 Females ( 13 50 years) 88 Infants (< 1 Year) 29 Children ( 1 6 years) 28 d. Cancer Aggregate Risk The cancer aggregate risk assessment includes chronic dietary exposures from residues in food and water and a consideration of potential exposures from the residential uses of a chemical. In the case of diuron, separate cancer risk assessments have been conducted for the parent diuron and for its water metabolite, MCPDMU. EPA considers separate cancer assessments to be warranted because the target organs and Q 1* are different for parent and metabolite. The MCPDMU assessment relies on toxicity data from monuron, a structurally similar molecule that was formerly a registered pesticide. Like chronic dietary risk, potential cancer risk is calculated by using average consumption values for food and average residue values for those foods over a 70 year lifetime. The chronic exposure value is typically combined with a linear low dose ( Q 1*) approach to determine the lifetime ( cancer) risk estimate.

Aggregate Cancer Risk from Diuron Although estimated exposure to diuron residues in food alone results in a cancer risk estimate of 1.68 x 10 6 for the general population, the Agency believes that this estimate is not of concern based on several protective assumptions in the assessment. The estimates of exposure from food are based largely on field trial data conducted at the maximum application rates, with adjustments only for percent crop treated and some processing data. Further, even though PDP monitoring data show no detectable residues of diuron parent in any food commodity, EPA has made the protective assumption that all diuron converts to metabolites and has determined that these metabolite residues are as toxic as the parent compound. Drinking water monitoring data for several states with high usage of diuron, indicate average detections in the 0.05 0.28 ppb range. These levels, if sustained over a lifetime of exposure would result in risk estimates in the 1 x 10 6 range. Thus, combined food and drinking water risks would be < 3 x 10 6. 34 The residential uses of diuron result in only short term exposures, generally less than 7 days per year, therefore the diuron cancer assessment based on Residential SOP provides a very conservative estimate of potential cancer risk. The assessment assumes an upper bound dermal absorption factor, even though no dermal toxicity was observed in a 28 day rabbit dermal toxicity study. Further, EPA has assumed 100% absorption by the inhalation route. Given the low vapor pressure of diuron, 2 x 10 7mm Hg @ 30 C, absorption by the inhalation route is likely to be low. Finally, because of the low percent of paint containing diuron (< 1% ), lifetime exposure to home applicators of diuron containing products is likely to be negligible.

Aggregate Risk from MCPDMU For the MCPDMU aggregate assessment, EPA considered the potential contributions from drinking water and consumption of catfish. Because MCPDMU is only formed in water, these are the only potential sources of exposure to MCPDMU. Based on modeled estimates, the EEC for MCPDMU is 6.94 ppb, and represents a slight exceedance of the cancer DWLOC of 2 ppb. However, as mentioned in the Dietary Risk from Drinking Water Section, drinking water monitoring data was used to estimate the EECs of diuron and its degradates in drinking water. The monitoring data indicates the EEC for diuron is < 1 ppb, including the degradates. Although the water monitoring data do not include data on the degradates of diuron, the Agency has increased the EECs by 20 percent, as suggested by modeling, to account for the degradates. In addition, environmental fate data are required to confirm estimates of the concentrations and persistence of MCPDMU in water.

Table 13. Summary of Cancer DWLOC Calculations for MCPDMU Population Subgroup Surface Water EECs ( ppb) Ground Water EECs ( ppb) DWLOCcancer ( ppb)

U. S. Population < 1* 1.4 2.0 * For comparative purposes, the modeled estimate for the surface water EEC is 6.94 ppb.

5. Occupational Risk Occupational workers can be exposed to a pesticide through mixing, loading, and/ or applying a pesticide, or re entering treated sites. Occupational handlers of diuron include: workers in right of way areas or industrial sites, workers in agricultural environments, workers applying paints or stains, workers in ornamental fish and catfish production and workers applying diuron to ornamental plants and trees in nurseries. Non cancer risk for all of these potentially exposed populations is measured by a Margin of Exposure ( MOE) which determines how close the occupational exposure comes to a No Observed Adverse Effect Level ( NOAEL). In the case of diuron, MOEs greater than 100 do not exceed the Agency's level of concern. When evaluating cancer risks for the occupational population, EPA closely examines risks in the 1x10 4 to 1x10 6 range and seeks cost effective ways to reduce occupational cancer risks to the greatest extent feasible, preferably 1x10 6 or less. 35 Calculations of noncancer risk based on inhalation exposure indicate that the inhalation margins of exposure ( MOEs) are more than 100 with PPE or engineering controls for all of the short term occupational exposure scenarios except applying sprays with a high pressure handwand. Sixteen of the 31 occupational scenarios were identified as having intermediate term durations of exposure. Of these, none have a non cancer risk of concern for intermediate term inhalation exposure with PPE or engineering controls. A noncancer postapplication risk assessment was not conducted, since no systemic toxicity by the dermal route is expected for the short or intermediate term durations. Postapplication cancer risks for private growers were calculated at both the typical application rate and the maximum application rate for each crop grouping.

Occupational risk assessments were conducted for the use of diuron as a mildewcide in paint. Four occupational handler scenarios were identified for the use of diuron in paint and are expected to be of short and intermediate term exposure duration. The calculations of short and intermediate term inhalation risk from the use of diuron in paint indicate that MOEs are more than 100 at the assessed level of mitigation for all the exposure scenarios, except applying paints with an airless sprayer ( indoors). At the assessed level of mitigation, all paint scenarios have potential cancer risks between 1 x 10 4 and 1 x 10 6. Occupational postapplication exposures to paint containing diuron may occur in industrial settings around open vats used in paint processing. Inhalation and dermal exposures may also occur while maintaining industrial equipment. No postapplication exposure data have been submitted to determine the extent of postapplication exposures in the industrial settings. Nonetheless, inhalation exposures are expected to be minimal because of the low vapor pressure of diuron ( 2 x 10 7 mm Hg at 30

C) and aerosol formation is not expected. Dermal postapplication exposures are expected to be lower than when handling/ loading the formulated product. Therefore, postapplication exposures in the industrial settings are expected to be minimal and not of concern.

Occupational risk assessments were also conducted for the use of diuron as an algaecide in commercial fish ponds. Four short term occupational handler scenarios were identified for the use of diuron in commercial fish production and the inhalation MOEs from all four of the commercial fish production scenarios were greater than 100 at the baseline level of mitigation and are not of concern. With maximum mitigation measures ( engineering control level), all four scenarios have estimated cancer risks of less than 1 x 10 6 and are not of concern. Occupational postapplication exposure to diuron in treated fish production ponds is not likely to result in a risk of concern based on the extremely high dilution rate 36 a. Toxicity The acute toxicity profiles for diuron is listed previously in Table 3. Table 14 details the toxicity endpoints used in the occupational risk assessment for diuron.

Table 14: Toxicity Endpoints for Diuron Risk Assessment Route / Duration NOAEL ( mg/ kg/ day) Effect Study Uncertainty Factors and Safety Factors Short and intermediateterm Dermal No systemic toxicity following repeated dermal dosing at 1200 mg/ kg/ day was seen in the dermal toxicity study. Also, there is no developmental concern. No hazard was identified and no quantitative assessment is required.

Long term Dermala ( greater than six months) 1.0 ( LOAEL) Evidence of hemolytic anemia and compensatory hematopoiesis. Chronic toxicity/ carcinogenicity study in rats Interspecies: 10x Intraspecies: 10x FQPA: 1x Use of LOAEL instead of a NOAEL: 3x Short term Inhalationb 10 Decreased body weight and food consumption Developmental toxicity study in rabbits Interspecies: 10x Intraspecies: 10x FQPA: 1x Intermediateterm Inhalationb 1.0 Altered hematological parameters observed at six months Chronic toxicity/ carcinogenicity study in rats Interspecies: 10x Intraspecies: 10x FQPA: 1x Long term Inhalationb 1.0 ( LOAEL) Evidence of hemolytic anemia and compensatory hematopoiesis Chronic toxicity/ carcinogenicity study in rats Interspecies: 10x Intraspecies: 10x FQPA: 1x Use of a LOAEL instead of a NOAEL: 3x Cancer Known/ lik ely human carcinogen Q1* = 1.91 x 10 2 Urinary bladder carcinoma in both sexes of the Wistar rat, kidney carcinomas in the male rat ( a rare tumor), and mammary gland carcinomas in the female NMRI mouse Carcinogenicity study in rats and mice a An oral endpoint was used for dermal exposure: dermal absorption factor of 4% of oral exposure shall be used. b An oral endpoint was used for inhalation exposure: inhalation exposure assumed equivalent to oral exposure.

b. Agricultural Handler Exposure Based on the registered use patterns, EPA has identified 31major exposure scenarios for which there is potential occupational handler exposure during mixing, loading, and applying products containing diuron. These scenarios are as follows:

( 1a) mixing/ loading liquid formulations for aerial application; ( 1b) mixing/ loading liquid formulations for chemigation; ( 1c) mixing/ loading liquid formulations for groundboom application; 37 ( 1d) mixing/ loading liquid formulations for rights of way sprayers; ( 1e) mixing/ loading liquid formulations for high pressure hand wand; ( 2a) mixing/ loading dry flowables for aerial application; ( 2b) mixing/ loading dry flowables for chemigation; ( 2c) mixing/ loading dry flowables for groundboom application; ( 2d) mixing/ loading dry flowables for rights of way spray application; ( 2e) mixing/ loading dry flowables for high pressure hand wand; ( 3a) mixing/ loading wettable powders for aerial application; ( 3b) mixing/ loading wettable powders for chemigation; ( 3c) mixing/ loading wettable powders for groundboom application; ( 3d) mixing/ loading wettable powders for rights of way spray application; ( 3e) mixing/ loading wettable powders for high pressure hand wand; ( 4) loading granulars for tractor drawn spreaders; ( 5) applying sprays for aerial application; ( 6) applying sprays for groundboom application; ( 7) applying sprays with a rights of way sprayer; ( 8) applying sprays with a high pressure hand wand; ( 9) applying granulars for a tractor drawn spreader; ( 10) applying granulars with a spoon; ( 11) applying granulars for hand application; ( 12) flagging aerial spray applications; ( 13) mixing/ loading/ applying liquids with a low pressure hand wand; ( 14) mixing/ loading/ applying liquids with a backpack sprayer; ( 15) mixing/ loading/ applying wettable powders with a low pressure hand wand; ( 16) loading/ applying granulars with a pump feed backpack spreader; ( 17) loading/ applying gravity feed backpack spreader; ( 18) loading/ applying granulars for a belly grinder application; and ( 19) loading/ applying granulars with a push type spreader.

Since granulars are only used on non crop/ utility areas, aerial application of granulars and flaggers supporting aerial granular applications were not assessed.

For agricultural handlers, the estimated exposures initially are assessed assuming handlers are using baseline attire ( i. e., long sleeve shirt, long pants, shoes, and socks). If risk estimates exceed the level of concern for a given scenario with baseline attire, then exposures are assessed with the addition of personal protective equipment ( i. e., chemical resistant gloves, double layer body protection, and/ or a respirator) as required. In general, the Agency uses the least PPE necessary to achieve risk estimates that do not exceed the level of concern. If the risk estimates exceed the Agency's level of concern ( i. e., if MOE < 100) for a given scenario even with the addition of PPE, then the risks are assessed with the use of engineering controls ( i. e., closed system mixing/ loading and enclosed cabs or cockpits for applying and flagging). 38 Agricultural Handler Data Sources The analyses for the diuron risk assessment were performed using the following sources of data:

° Outdoor Residential Exposure Task Force ( ORETF). The task force recently submitted proprietary data to the Agency on hose end sprayers, push type granular spreaders, and handgun sprayers ( MRID # 44972201). The ORETF data were used in this assessment in place of PHED data for the " loading/ applying granulars using a push type spreader" scenario.

° Available data were used to assess exposures and risks to occupational handlers loading and applying granulars using a scoop and bucket, these estimates are used as range finding estimates for the applications made with a spoon or by hand.

° Pesticide Handlers Exposure Database ( PHED). PHED was designed by a task force of representatives from the US EPA, Health Canada, the California Department of Pesticide Regulation, and member companies of the American Crop Protection Association, now known as Crop Life America. It is a software system consisting of two parts  a database of measured exposure values for workers involved in the handling of pesticides under actual field conditions and a set of computer algorithms used to subset and statistically summarize the selected data. Currently, the database contains values for over 1,700 monitored individuals ( i. e., replicates). The quality of the data and exposure factors represents the best sources of data currently available to the Agency for completing these kinds of assessments.

Agricultural Handler Exposure Assumptions The following assumptions and factors were used in order to complete the exposure and risk assessments for occupational handlers/ applicators:

Calculations were completed for a range of maximum application rates for crops specified on current diuron labels and in the Label Usage and Information System ( LUIS) report. These rates were assessed in order to bracket risk levels associated with the various use patterns.

° Average body weight of an adult handler was assumed to be 70 kg.

° Daily ( 8 hour workday) acres and volumes ( as appropriate) to be treated in each scenario include: