{"abstract":"The U.S. Environmental Protection Agency (EPA) is announcing final regulatory determinations for nine contaminants listed on the fifth Contaminant Candidate List. Specifically, the Agency is making final determinations not to regulate 2-aminotoluene, cylindrospermopsin, ethoprop, microcystins, molybdenum, permethrin, profenofos, tebuconazole, and tribufos. The Safe Drinking Water Act (SDWA) requires the EPA to make regulatory determinations every five years on at least five unregulated contaminants. A regulatory determination is a decision about whether or not to begin the process to propose and promulgate- a national primary drinking water regulation (NPDWR) for an unregulated contaminant.","action":"Regulatory determinations.","agencies":[{"raw_name":"ENVIRONMENTAL PROTECTION AGENCY","name":"Environmental Protection Agency","id":145,"url":"https://www.federalregister.gov/agencies/environmental-protection-agency","json_url":"https://www.federalregister.gov/api/v1/agencies/145","parent_id":null,"slug":"environmental-protection-agency"}],"body_html_url":"https://www.federalregister.gov/documents/full_text/html/2026/03/19/2026-05452.html","cfr_references":[{"chapter":null,"citation_url":null,"part":141,"title":40}],"citation":"91 FR 13227","comment_url":null,"comments_close_on":null,"correction_of":null,"corrections":[],"dates":"For the purpose of judicial review, the determinations not to regulate in this document are issued as of March 19, 2026.","disposition_notes":null,"docket_ids":["EPA-HQ-OW-2024-0456","FRL-10774-02-OW"],"dockets":[{"supporting_documents":[{"title":"NCBI. 2023b. PubChem Compound Summary for CID 38779, Profenofos","document_id":"EPA-HQ-OW-2024-0456-0093"},{"title":"International Programme on Chemical Safety (IPCS). 1998. Concise International Chemical Assessment Document (CICAD) No. 7: o-Toluidine","document_id":"EPA-HQ-OW-2024-0456-0089"},{"title":"D.C. Circuit Court (D.C. Cir.). 2023 . National Resources Defense Council v. Michael S. Regan, Administrator, U.S. Environmental Protection Agency and Environmental Protection Agency, 67 F.4th 397","document_id":"EPA-HQ-OW-2024-0456-0087"},{"title":"WHO. 2020b. Cyanobacterial Toxins: Microcystins. Background Document for Development of WHO Guidelines for Drinking-Water Quality and Guidelines for Safe Recreational Water Environments","document_id":"EPA-HQ-OW-2024-0456-0085"},{"title":"USEPA. 2015c. Ethoprop: Draft Human Health Risk Assessment for Registration Review. September 15, 2015, memo from Office of Chemical Safety and Pollution Prevention","document_id":"EPA-HQ-OW-2024-0456-0084"},{"title":"WHO. 2021. Manganese in Drinking-Water. Background Document for Development of WHO Guidelines for Drinking-Water Quality","document_id":"EPA-HQ-OW-2024-0456-0071"},{"title":"USEPA. 2001a. Statistical Design and Sample Selection for the Unregulated Contaminant Monitoring Regulation (1999)","document_id":"EPA-HQ-OW-2024-0456-0068"},{"title":"USEPA. 2002. A Review of the Reference Dose and Reference Concentration Process. Risk Assessment Forum","document_id":"EPA-HQ-OW-2024-0456-0064"},{"title":"USEPA. 2009a. Drinking Water Contaminant Candidate List 3 – Final","document_id":"EPA-HQ-OW-2024-0456-0060"},{"title":"Wolansky et al. 2006. Relative Potencies for Acute Effects of Pyrethroids on Motor Function in Rats","document_id":"EPA-HQ-OW-2024-0456-0057"}],"agency_name":"EPA","documents":[{"comment_count":null,"comment_start_date":null,"updated_at":"2026-03-19T14:57:45.450-04:00","comment_url":"https://www.regulations.gov/commenton/EPA-HQ-OW-2024-0456-0107","allow_late_comments":false,"id":"EPA-HQ-OW-2024-0456-0107","comment_end_date":null,"regulations_dot_gov_open_for_comment":false}],"supporting_documents_count":104,"id":"EPA-HQ-OW-2024-0456","title":"Regulatory Determinations for Contaminants on the Fifth Contaminant Candidate List"}],"document_number":"2026-05452","effective_on":null,"end_page":13236,"executive_order_notes":null,"executive_order_number":null,"explanation":null,"full_text_xml_url":"https://www.federalregister.gov/documents/full_text/xml/2026/03/19/2026-05452.xml","html_url":"https://www.federalregister.gov/documents/2026/03/19/2026-05452/announcement-of-final-regulatory-determinations-for-contaminants-on-the-fifth-drinking-water","images":{"ER19MR26.001":{"large":"https://img.federalregister.gov/ER19MR26.001/ER19MR26.001_large.png","medium":"https://img.federalregister.gov/ER19MR26.001/ER19MR26.001_medium.png","original_size":"https://img.federalregister.gov/ER19MR26.001/ER19MR26.001_original_size.png"}},"images_metadata":{"ER19MR26.001":{"large":{"identifier":"ER19MR26.001","content_type":"image/png","size":55437,"width":823,"sha":"e32bc03f87e7703a5bf06814f5f3b311","url":"https://img.federalregister.gov/ER19MR26.001/ER19MR26.001_large.png","height":665},"medium":{"identifier":"ER19MR26.001","content_type":"image/png","size":21935,"width":476,"sha":"36190b0be2e135464437e2817bda561f","url":"https://img.federalregister.gov/ER19MR26.001/ER19MR26.001_medium.png","height":385},"original_size":{"identifier":"ER19MR26.001","content_type":"image/png","size":767072,"width":3600,"sha":"d33f71d345d14b376ca330dfa2dd4706","url":"https://img.federalregister.gov/ER19MR26.001/ER19MR26.001_original_size.png","height":2910}}},"json_url":"https://www.federalregister.gov/api/v1/documents/2026-05452?publication_date=2026-03-19","mods_url":"https://www.govinfo.gov/metadata/granule/FR-2026-03-19/2026-05452/mods.xml","not_received_for_publication":null,"page_length":10,"page_views":{"count":1273,"last_updated":"2026-05-01 10:15:05 -0400"},"pdf_url":"https://www.govinfo.gov/content/pkg/FR-2026-03-19/pdf/2026-05452.pdf","presidential_document_number":null,"proclamation_number":null,"public_inspection_pdf_url":"https://public-inspection.federalregister.gov/2026-05452.pdf?1773837923","publication_date":"2026-03-19","raw_text_url":"https://www.federalregister.gov/documents/full_text/text/2026/03/19/2026-05452.txt","regulation_id_number_info":{},"regulation_id_numbers":[],"regulations_dot_gov_info":{"supporting_documents":[{"title":"NCBI. 2023b. 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