EPA sets interim limits on hypochlorite bleach to reduce degradation to perchlorate

Tom Neltner, J.D.is Chemicals Policy Director and Maricel Maffini, Ph.D., Consultant

On May 1, 2018, Environmental Protection Agency’s (EPA) Office of Pesticide Programs (OPP) made an interim pesticide registration decision[1] for hypochlorite bleach used to disinfect drinking water. The office decided to require the “Precautionary Statements” section of the bleach’s pesticide label to include advisory best management practices to minimize the formation of chlorate and perchlorate. The new label will state:

“The following practices help to minimize degradant formation in drinking water disinfection:

  • It is recommended to minimize storage time.
  • It is recommended that the pH solution be in the range of 11-13.
  • It is recommended to minimize sunlight exposure by storing in opaque containers and / or in a covered area. Solutions should be stored at lower temperatures. Every 5º C reduction in storage temperature will reduce degradant formation by a factor of two.
  • Dilution significantly reduces degradant formation. For products with higher concentrations, it is recommended to dilute hypochlorite solutions with cool, softened water upon delivery, if practical for the application.”

EDF submitted comments in November 2017 supporting OPP’s proposed label changes and requesting specific changes to the language including making the advice to users mandatory. We also asked the agency to extend the changes to hypochlorite bleach used to treat produce and to disinfect food handling equipment.

The agency declined to make our requested changes to the proposed language because:

  • The feasibility of different drinking water utilities to implement the practices varies based on geographic location and facility logistics.
  • The results of a proposed model predicting the risk of perchlorate on infant and fetal brain development was not complete. They may affect the final decision on the label. This model was developed by EPA’s Office of Water and the Food and Drug Administration (FDA).
  • The agency did not have the data showing significant concern that hypochlorite used to treat food handling equipment was a problem when used according to label instructions.

OPP indicated it will continue to monitor progress on the EPA/FDA perchlorate risk model carried out by the agency’s Office of Water and may reevaluate the options before a final reregistration decision is made in 2022. The agency is under a court order to finalize the model and issue a proposed maximum contaminant level goal for perchlorate in October of this year.

Based on the positive feedback from the peer review panel on the model, our assessment of its implications, and the high perchlorate levels found in foods, such as produce, that are often treated with bleach water, we maintain that EPA should extend the best management practices to hypochlorite used to disinfect food and food handling equipment. We encourage any food company concerned about perchlorate contamination in its products to work with its suppliers and follow the best management practices laid out by EPA in its decision.


[1] Sodium and calcium hypochlorite notice and the potassium hypochlorite notice are in separate rulemaking dockets.

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