Project #5085

Impact of Haloacetic Acid MCL Revisions on DBP Exposure and Health Risk Reduction

In Progress
Principal Investigator
Research Manager
Ms. Mary Smith
Hazen and Sawyer
Disinfection Byproducts (DBPs)
Water Quality


The U.S. Environmental Protection Agency (EPA) is considering changes to the disinfectant and disinfection byproducts (D/DBP) rule. Specifically, there may be a shift from the currently regulated five haloacetic acids (HAA5) to nine (HAA9), which would include four additional brominated compounds. Therefore, there is a need to better understand the toxicology, public health, treatment, and compliance implications of a shift from an HAA5- to HAA9-based regulation.

This project increases understanding of these implications by (1) assessing the potential impacts of new regulatory levels for HAA5, the brominated HAAs, or HAA9; (2) developing a database and analysis that will be made available to water systems for discussion with regulatory authorities; (3) evaluating the weight of evidence regarding the relative toxicity of HAA9 compounds; (4) building an understanding of the benefits of compliance technologies for a future rule; (5) providing guidance on the consequences of implementing changes to respond to a revised maximum contaminant level for HAAs; (6) and developing materials to support clear, concise communication about the issues surrounding a move from an HAA5- to HAA9-based regulation. Published in 2024.