EPA Finalizes Disinfectant Residue Test Methods for Surfaces

On June 13, EPA released test methods for detecting residues of two classes of disinfectants on hard surfaces after rinsing with water: quaternary ammonium compounds and phenolic compounds. These classes of chemicals are often found in products that make disinfectant claims, according to the agency. “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,” EPA states in press release.

A potable water rinse (PWR), EPA explains, may be necessary to remove potentially harmful chemical residues from a surface after disinfectants have been applied. If EPA lacks data for specific chemicals when evaluating dietary risk, the agency assumes that 100 percent of disinfectant residues on a surface will contact food, even after the surface is rinsed. According to EPA, this practice may lead to overly conservative risk assessments and mitigation measures that are more protective than necessary, compared to if chemical-specific data was used.

“Based on their chemical properties, [quaternary ammonium compounds and phenolic compounds] represent the range of disinfectant residues that could remain after a PWR,” EPA states. After rinsing, quaternary ammonium compounds are expected to leave the most residue on a surface, and the phenolic compounds are expected to leave the least. Users may modify the test methods developed for quaternary ammonium and phenolic compounds for other chemical classes that are active ingredients in products requiring PWRs. These methods will serve as guidance for residue studies when registering new and existing products and enable EPA to perform more accurate dietary risk assessments.

EPA’s finalized guidance for analyzing disinfectant residues on hard, non-porous surfaces after rinsing may be found on Regulations.gov. More information is available in EPA’s press release.

Related: Articles in The Synergist have addressed surface sampling for chemotherapy drugs and general contamination, as well as NIOSH’s 2023 guidance for surface sampling.