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By Edmond Lam, Assistant Director, and Cecilia Smith, Administrative Assistant, ACS Green Chemistry Institute
The EPA’s 2024 final risk management rule on dichloromethane (DCM) prohibits the distribution and most uses of DCM, aiming to minimize harmful health effects of the commonly used solvent. Adjusting to the new restriction presents a distinct challenge for the research community. Due to this challenge, the ACS GCI in collaboration with ACS Offices of Safety Programs and Government Affairs has developed a new online resource to assist with the transition to compliance with the new restriction.
In April 2024, the U.S. Environmental Protection Agency (EPA) released a final risk management rule prohibiting the distribution and use of a solvent that is found in many commercial products and used in numerous teaching and research labs across the country. Dichloromethane (known as methylene chloride or DCM) has been widely used as a solvent for mixing and for the purification of reaction products due to its solvent polarity and low flammability. However, despite its useful properties in industry and research, DCM is a very hazardous chemical as it can cause short-term adverse effects like dizziness as well as long-term impacts, such as cancer and liver damage, and in some cases can lead to death.
The EPA’s 2024 final ruling limits most uses of DCM and represents a significant milestone for the green chemistry and environmental health and safety communities, among others, in promoting human health and restricting a hazardous chemical whose detrimental health effects have been known for years. The ruling’s restriction on the distribution of DCM will take effect on May 5, 2025, and the restriction on the use of DCM in many commercial applications will go into effect on April 28, 2026.
Due to the prevalence of DCM use in the research community and the additional requirements for chemical hygiene plans mandated by OSHA, the ruling has caused much confusion and concern. To help clarify the matter, the ACS Green Chemistry Institute, in collaboration with the ACS Offices of Safety Programs and Government Affairs, has developed a new online resource to assist with the transition to compliance with the new restriction.
The new resource aims to answer the most common question that has arisen, “Can I continue to use DCM in the laboratory?” While using DCM in the laboratory falls into one of the for the EPA's 13 permitted use cases for the solvent, this comes with conditions of use that require a Workplace Chemical Protection Program (WCPP), which must be put into place by August 1, 2025. In addition to the challenges the short timeline for compliance presents, the WCPP could be costly for those who do not have the resources to monitor DCM levels or implement an exposure control plan according to EPA guidelines.
While presenting information regarding the allowed use cases of DCM, the new ACS page provides resources and information to help researchers and lab managers determine a course of action when they cannot comply with a WCPP. There are many safe alternative solvents to DCM which can be considered. Unfortunately, it is usually not a straightforward process to replace DCM with another solvent without considering the chemistry being performed, as DCM has been used in a wide range of applications with different reaction conditions and in a number of analytical techniques. Since experimental hazards can result from a variety of agents, conditions, and/or activities, it’s important to carefully consider the hazards and risks of the DCM substitute. Green chemistry and green engineering principles and lab safety protocol serve as excellent tools to minimize risks and determine a tailored DCM alternative while preventing “regrettable substitutions” that could be potentially worse than DCM. Since effective substitutes reduce the potential for harmful effects and do not create new risks, resources for evaluating the hazards and risks of potential substitutes are crucial.
In addition to highlighting the holistic, green chemistry informed approach needed to determine DCM replacements, the new resource page will also feature ACS GCI Pharmaceutical Roundtable online guides and tools, resources from the ACS Office of Safety Programs, and peer reviewed research papers to help the community make informed decisions on which types of solvents could be used to replace DCM in specific applications.
We welcome the community to contribute their best practices and research into DCM alternatives as the research community navigates through this process. You can explore additional safer alternatives and recent publications (and submit your own) at the Green Chemistry for Sustainability Platform.
While the community navigates this challenging transition period, it’s important to keep in mind that benzene and carbon tetrachloride, two harmful solvents, have largely been phased out of research lab use over the years. The transition away from these two solvents was brought about not only because of environmental health and safety concerns, but because of the research community’s ability to change their solvent use habits by making use of reliable scientific resources available to help make informed decisions.