EPA Revises Risk Determination for Methylene Chloride
A revised risk determination finalized by EPA on Nov. 10 finds that methylene chloride “presents an unreasonable risk of injury to human health.” According to EPA, methylene chloride is used as a solvent in vapor degreasing and metal cleaning as well as an ingredient in sealants and adhesive removers. The chemical also has consumer applications such as adhesives, sealants, degreasers, cleaners, and automobile products that contain methylene chloride.
Adverse human health effects from acute and chronic inhalation and dermal exposures to methylene chloride include neurotoxicity and liver effects, EPA notes. The agency also identifies risks for cancer from chronic inhalation and dermal exposures to the chemical. The severity and potential irreversibility of the health effects associated with exposures to methylene chloride prompted EPA to use its “whole chemical risk determination approach” for the chemical rather than making separate risk determinations for individual conditions of use.
The revised risk determination differs from previous risk evaluations of methylene chloride in that it does not assume that all workers exposed to the chemical always or properly wear personal protective equipment. This “reflects EPA’s recognition that certain subpopulations of workers exist that may be highly exposed” for a number of potential reasons, the agency explains in a press release. For example, some workers could have increased exposure if they are not covered by OSHA standards or if the OSHA permissible exposure limit alone may be inadequate for ensuring the protection of workers’ health, which EPA states “is the case for methylene chloride.”
OSHA’s permissible exposure limit for methylene chloride is 25 parts of methylene chloride per million parts of air as an 8-hour time-weighted average, and its action level is 12.5 ppm. The PEL was lowered to 25 ppm from 500 ppm in 1997. In a regulatory review of its methylene chloride standard published in 2010 (PDF), OSHA found that the standard “[remained] justified and necessary in light of ongoing hazards and fatalities” and that it should continue with no changes.
EPA intends to develop a risk management rule for methylene chloride.
“[EPA] will strive for consistency with existing OSHA requirements or best industry practices when those measures would address the identified unreasonable risk,” the agency explains. “EPA will propose occupational safety measures in the risk management process that would meet [the Toxic Substances Control Act’s] statutory requirement to eliminate unreasonable risk of injury to health and the environment.”
Related: An assessment published last year in JAMA Internal Medicine shows that methylene chloride-related fatalities continue to occur in the United States even with regulations and policies in place to address product labeling and worker protections.