EPA Releases Finalized Test Methods for Measuring Disinfectant Residue Levels on Hard Surfaces
Released on June 13, 2024
The U.S. Environmental Protection Agency (EPA) is releasing finalized test methods for measuring disinfectant residues on hard surfaces treated with two classes of disinfectants — quaternary ammonium compounds and phenolic compounds — after they have been rinsed with water (known as a potable water rinse or “PWR”). Estimating the amount of disinfectant residue after rinsing a treated surface, like cutting boards and countertops, with water is an important step in refining dietary risk assessments for disinfectant products that may come in contact with food.
Many disinfectant product labels require a water rinse after use on hard surfaces to remove potentially harmful chemical residues. Where EPA does not have chemical-specific data, the Agency assumes that 100% of the disinfectant residues applied to the treated surface will contact food after the surface is rinsed with water, when evaluating the dietary risks of disinfectant pesticides. This estimated food-contact residue amount is then included in EPA’s dietary exposure assessments, which may produce an overly conservative risk assessment for a product. This may lead to a conclusion that more protective mitigation measures are necessary to register the product than would be required with more chemical-specific data.
Quaternary ammonium compounds are chemicals used to kill bacteria, viruses, and mold and are found in many products like sprays and wipes making disinfectant claims. Phenolic compounds are used to kill bacteria and are found in household and consumer products that claim to clean and disinfect treated surfaces. Based on their chemical properties, these two classes represent the range of disinfectant residues that could remain after a PWR. The quaternary ammonium compounds are expected to leave the most residues on the treated surfaces after the PWR, while the phenolic compounds are expected to leave the least, compared to other chemical classes commonly used in disinfectants and other cleaning products. The analytical techniques described in the finalized test methods were developed for quaternary ammonium and phenolic compounds, but can also be modified for use with other chemical classes of active ingredients in disinfectant products that require a PWR.
These standardized test methods will not only serve as guidance in conducting residue studies in support of new and existing disinfectant product registration, but will also enable more refined dietary risk assessments by the Agency through the use of chemical-specific residue data in lieu of the 100% default value. EPA also plans to further examine the data from these test methods to develop a more refined default residue value (<100%) that could be used in future assessments when chemical-specific residue data are not available for a disinfectant active ingredient.
The test methods announced today were previously made available for public comment from Oct. 15, 2021, to Feb. 12, 2022. The comments received were generally supportive of EPA’s approach. The test methods and responses to the comments received can be viewed in docket ID EPA-HQ-OPP-2021-0626 at www.regulations.com.
Learn more from EPA about safe and effective use of disinfectants.