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Draft Risk Assessment Document – Proposed Interim Action Level for Dieldrin

Draft Risk Assessment Document – Proposed Interim Action Level for Dieldrin

JUNE 10, 2024 (Tiyan, Guam) – In accordance with the Guam Safe Drinking Water Act as reenacted through Guam Public Law 35-115, the Guam Environmental Protection Agency (Guam EPA) seeks to establish Interim Action Levels (IAL) for Dieldrin in drinking water.


Dieldrin is a human-made chemical used as an insecticide from the 1950s until 1987. Dieldrin has been identified as a probable carcinogen by the U.S. EPA and exposure to trace levels over long durations of time may increase the likelihood of developing cancer. Dieldrin has been detected in Guam’s drinking water. Levels of dieldrin in Guam’s public water systems range from non-detect to 1.9 micrograms per liter (ug/L or parts per billion – ppb). Dieldrin has been found at levels above the laboratory detection limit of 0.01 ppb in some Guam Waterworks Authority active production wells.

Through authority pursuant to 10 GCA § 53113(a), Guam EPA, upon identifying a contaminant in a public water system that may present an unacceptable health risk to the public, may establish IALs for contaminants for which maximum contamination levels have not been established by the U.S. EPA. Guam EPA, in collaboration with the U.S. EPA has produced a draft risk assessment document (DRAD) describing the technical and scientific methods and parameters utilized to determine the proposed IALs to be established for dieldrin.

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The DRAD is available for public review and comment beginning June 10, 2024 through August 14, 2024, Monday to Friday (excluding GovGuam holidays), 8:30 a.m. to 4:30 p.m. at the Guam EPA Administration Building located at 17-3304 Mariner Avenue in Tiyan. The DRAD may be viewed above and downloaded by CLICKING HERE

Written comments DUE: WEDNESDAY AUGUST 14, 2024
Written comments may be submitted to the agency via hand delivery or mail and must be addressed to: Administrator, c/o Guam EPA 17-3304 Mariner Avenue Barrigada, Guam 96913-1617. Written comments may be emailed to: julie.mendoza@epa.guam.gov with the subject: Proposed Dieldrin IAL. Comments must include the name, mailing address and email address of the party commenting. Written comments must be received, or postmarked no later that 5 p.m. on August 14, 2024. Fax submissions will not be accepted.

PUBLIC HEARING: Monday, June 24, 2024 at 3 P.M.
Pursuant to 10 GCA § 53113(c)(2), a public hearing for the consideration of an IAL shall be held. The hearing will take place at the Guam EPA Administration Conference Room located at 17-3304 Mariner Avenue Barrigada, Guam on Monday, June 24, 2024 at 3 p.m. The hearing will also be livestreamed on youtube.com/guamepa. For more information, contact Julie Mendoza at 671.300.9026 or julie.mendoza@epa.guam.gov

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