On April 30, 2024, the EPA banned many uses of methylene chloride, a chemical widely used as a paint stripper and in industrial applications, based on an "unreasonable risk to human health." This presents a total reversal of their earlier conclusions that methylene chloride did not pose an unreasonable risk. How did EPA use the same data to reach two opposing conclusions?
Methylene chloride is used in adhesives, paint and coating products, metal cleaning, aerosols, and in the manufacture of other chemicals. It is also used as a paint stripper and as a laboratory solvent. Between 2016 and 2019, the total production volume ranged from 100 to 500 million pounds. EPA Administrator Michael Regan said that the new rule, "brings an end to unsafe methylene chloride practices and implements the strongest worker protection possible for the few remaining industrial uses, ensuring no one in this country is put in harm's way by this dangerous chemical" [emphasis added] However, there are significant exceptions (carve-outs) to the rule, which raise the question of how impactful the ban is. Toxic Substances Control Act Risk (TSCA) This begins with the Toxic Substances Control Act (TSCA), where the EPA uses risk assessments to determine whether a chemical presents an unreasonable risk of injury to health under the conditions of use. In 2020, the EPA's risk assessment concluded that it did not present an unreasonable risk to human health. The EPA's revised assessment, the basis for the new rule, used the same data as in the 2020 assessment; however, the EPA revised several aspects of the risk assessment process: In 2020, EPA made individual risk determinations based on individual conditions of use. [1] In 2022, the EPA aggregated these numbers as a "whole chemical approach, consisting of one overall risk determination for methylene chloride because it 'better aligns with the statute and Congress' intent,' and enables the Agency's risk determinations to better reflect the potential for combined exposures across multiple conditions of use". In 2020, the EPA assumed that personal protective equipment (PPE) was always provided and used in occupational settings; now, they assume no use of PPE. This was based on the recognition that some workers may not be covered under Occupational Safety and Health Administration (OSHA) standards or because…