DPR 24-001 – Health Risk Mitigation for 1,3-Dichloropropene

DPR 24-001 Health Risk Mitigation for 1,3-Dichloropropene (Notice 11/15/24; Comment period closed 1/24/25; “15-day” comment period 6/5/25-6/20/25)

DPR proposes to adopt Title 3, California Code of Regulations (3 CCR) section 6448.5 and amend sections 6000, 6448, 6448.2, 6448.4, 6624, and 6626. In summary, the proposed action restricts the use of 1,3-dichloropropene (1,3-D) to mitigate the potential 40-year working lifetime cancer risk to occupational bystanders. The proposed action establishes buffer zone distances (distances from the edge of a treated area where certain activities are restricted) and requires DPR to include an evaluation in the 1,3-D Annual Report of whether the 1,3-D air concentration in any township exceeds the acceptable level of 0.21 part per billion and to develop appropriate measures to reduce exposures if target air concentration levels are exceeded. DPR also proposes to repeal the document “1,3-Dichloropropene Field Fumigation Requirements, Est January 1, 2024,” and adopt the document “1,3-Dichloropropene Field Fumigation Requirements, Rev. January 1, 2026,” which is incorporated by reference in existing sections 6448, 6448.2, 6624, and 6626. A copy of this document is posted below.

The three in-person public hearings were held on January 8, 16, and 21, and one virtual public hearing was held on January 10 to receive oral and/or written comments regarding the proposed action.

On June 5, 2025, DPR issued a Notice of Modifications to Text of Proposed Action and Notice of Addition of Documents to the Rulemaking File. DPR will accept written comments relevant to the modifications and additional documents between June 5, 2025, and June 20, 2025.

• 11/15/2024 - 01/24/2025
• “15-day” comment period: 06/05/2025 - 06/20/2025

Attachments

• Notice of Proposed Regulatory Action - English pdf  
• Aviso De Acción Reglamentaria Propuesta - Spanish pdf  
• Text of Proposed Regulations - English pdf  
• 1,3-Dichloropropene Field Fumigation Requirements Established January 1, 2024 - English pdf  
• 1,3-Dichloropropene Field Fumigation Requirements Revised January 1, 2026 - English pdf  
• Initial Statement of Reasons and Public Report - English pdf  
• Economic and Fiscal Impact Statement - English pdf  
• 15-Day Notice Documents
• Notice of Modifications to Text of Proposed Action and Notice of Addition of Documents to Rulemaking File - English pdf  
• Aviso de Modificaciones al Texto de la Acción Propuesta y un Aviso de Adición de Documentos al Expediente de Formulación de Reglas - Spanish pdf  
• Text of Modified Regulations - English pdf  
• Modified “1,3-Dichloropropene Field Fumigation Requirements, rev. January 1, 2026” - English pdf  
• DPR. 2025. “Addendum to the Initial Statement of Reasons.” Department of Pesticide Regulation. - English pdf  
• Luo, Yuzhou. 2022. “Modeling for mitigation measures to reduce acute exposure from 1,3-Dichloropropene, modeling approach #2,” Department of Pesticide Regulation Report, September 12, 2022. - English pdf  
• Luo, Yuzhou. 2023. “Addendum: Modeling for mitigation measures to reduce acute exposure from 1,3-Dichloropropene, Revised setback tables,” Department of Pesticide Regulation Report, April 3, 2023. - English pdf  
• Mace, Kevi. 2025. “Potential net revenue loss for tree and grape growers,” May 16, 2025. California Department of Food and Agriculture memorandum. - English pdf  
• Bartell, Scott. 2025. “External Scientific Peer Review of ‘Update to the Health-Based Recommendations to Mitigate Cancer Risk of Occupational Bystander Exposure to 1,3- Dichloropropene’ and its associated documents,” University of California, Irvine, Joe C. Wen School of Population & Public Health, January 12, 2025. - English pdf  
• Frewer, Lynn. 2025. “CalEPA Peer Review Programme, OEHHA 1,3-D occupational health-based recommendations,” Newcastle University, Newcastle Upon Tyne, UK, January 2, 2025. - English pdf  
• Brown, Colin. 2019. “HYDRUS-simulated flux estimates of 1,3-dichloropropene maximum period-averaged flux and emission ratio for approved application methods,” Department of Pesticide Regulation Report, October 17, 2019.
• Brown, Colin. 2022. “Updates to HYDRUS-simulated flux estimates of 1,3-dichloropropene maximum period-averaged flux and emission ratios,” Department of Pesticide Regulation Report, September 22, 2022.
• DPR. 2016a. “Response to comments by OEHHA on DPR-HHAB’s draft 1,3-dichloropropene risk assessment document (dated August 31, 2015),” August 6, 2016. Department of Pesticide Regulation.
• DPR. 2016b. “Response to comments by US EPA on DPR-HHAB’s draft 1,3-Dichloropropene Risk Characterization Document dated August 31, 2015,” September 8, 2016. Department of Pesticide Regulation.
• DPR. 2016c. “Responses to comments by Dr. Urmila P. Kodavanti on DPR-HHAB’s draft 1,3- Dichloropropene Risk Characterization Document dated Aug. 31, 2015.” September 8, 2016. Department of Pesticide Regulation.
• DPR. 2016d. “Responses to comments by Dr. Richard A. Fenske on DPR-HHAB’s draft 1,3- Dichloropropene Risk Characterization Document dated November 19, 2015.” September 8, 2016. Department of Pesticide Regulation.
• DPR. 2016e. “Responses to comments by Dr. Weisueh A. Chiu on DPR-HHAB’s draft 1,3- Dichloropropene Risk Characterization Document dated August 31, 2015.” September 14, 2016. Department of Pesticide Regulation.
• DPR. 2016f. “Response to comments by Dow AgroSciences on DPR-HHAB’s draft 1,3- Dichloropropene Risk Characterization Document dated Aug. 31, 2015.” November 8, 2016. Department of Pesticide Regulation.
• DPR. 2015b. “1,3-Dichloropropene Risk Characterization Document: Inhalation Exposure to Workers, Occupational and Residential Bystanders and the General Public,” December 31, 2015. Department of Pesticide Regulation.
• DPR. 2024a. “Review by the Toxic Air Contaminant Workgroup of Documents Related to the Draft 1,3-Dichloropropene Occupational Bystander Regulations, November 2024.” Department of Pesticide Regulation document.
• DPR. 2024b. “Agricultural Pest Control Advisory Committee Agenda, December 11, 2024.” Department of Pesticide Regulation.
• DPR. 2024c. “Pesticide Registration and Evaluation Committee Agenda, November 15, 2024.” Department of Pesticide Regulation.
• Henderson, Julie. 2024. “Risk Management Directive for Occupational Bystander Cancer Risk from 1,3-Dichloropropene (1,3-D),” Department of Pesticide Regulation Memorandum, March 6, 2024.
• Kandelous, Maziar. 2019. “A Comparison Between Field-Estimated and HYDRUS-Simulated Emission of 1,3-Dichloropropene From Agricultural Fields, October 17, 2019.” Department of Pesticide Regulation Report.
• Luo, Yuzhou. 2019a. “Evaluating AERMOD for Simulating Ambient Concentrations of 1,3-Dichloropropene, October 17, 2019.” Department of Pesticide Regulation Report.
• Luo, Yuzhou. 2019b. “AERFUM: An Integrated Air Dispersion Modeling System for Soil Fumigants, October 17, 2019.” Department of Pesticide Regulation Report.
• Luo, Yuzhou and Randy Segawa. 2024. “Modeling for Evaluating Occupational Bystander Cancer Risk From 1,3-Dichloropropene, August 29, 2024.” Department of Pesticide Regulation Report.
• Mace, Kevi., F. Ganjisaffar, S. Rabourn, and R. Goodhue. 2024a. “1,3-Dichloropropene Occupational Safety Regulation Economic Impact Report,” August 1, 2024. California Department of Food and Agriculture and University of California, Davis.
• Mace, Kevi. 2024b. “Acreage Treated With Non-TIF Methods and Estimated Annual Cost of Adding TIF Tarp,” August 8, 2024. California Department of Food and Agriculture memorandum.
• Mace, Kevi. 2024c. “Number of Farms Using 1,3-Dichloropropene-Updated,” August 1, 2024. California Department of Food and Agriculture memorandum.
• Marks, Teresa. 2016a. “Comments on the Draft Risk Management Directive for 1,3-Dichloropropene (1,3-D) and Responses” October 6, 2016. Department of Pesticide Regulation Letter.
• Marks, Teresa. 2016b. “Risk Management Directive and Mitigation Guidance for Cancer Risk from 1,3-Dichloropropene (1,3-D),” October 6, 2016. Department of Pesticide Regulation Memorandum.
• OEHHA. 2023. “Health-Based Recommendations to Mitigate Cancer Risk of Occupational Bystander Exposure to 1,3-Dichloropropene,” December 13, 2023. Office of Environmental Hazard Assessment memorandum.
• Update to the Health-Based Recommendations to Mitigate Cancer Risk of Occupational Bystander Exposure to 1,3-Dichloropropene - English pdf  
• Request for External Scientific Peer Review of the Scientific Basis of OEHHA Memorandum: “Update to the Health-Based Recommendations to Mitigate Cancer Risk of Occupational Bystander Exposure to 1,3- Dichloropropene” and its associated documents - English pdf  
• Estimation of Lifetime Exposure for Occupational Bystanders When Regularly Working at the Edge of 1,3-Dichloropropene Treated Fields - English pdf  
• U.S. EPA. 2017. “Revisions to the Guideline on Air Quality Models: Enhancements to the AERMOD Dispersion Modeling System and Incorporation of Approaches To Address Ozone and Fine Particulate Matter.” U.S. Environmental Protection Agency. Federal Register, Vol. 82, No. 10, January 17, 2017.

Hearings