The US Environmental Protection Agency’s (EPA) broad ban on most industrial and commercial uses of dichloromethane (DCM) that has just come into force means more work and expense for many university chemistry departments.
DCM, also known as methylene chloride, is a solvent widely used in academic organic chemistry labs that was also commonly used as degreaser and paint stripper in the US. Exposure to the chemical was linked to dozens of deaths in the country between 1980 and 2024, primarily related to consumer and professional paint and coating removal. The EPA notes that DCM is neurotoxic and can cause heart and liver damage, as well as various cancers.
Two years ago, President Biden’s EPA finalised a ban on most remaining uses of DCM in the country. Last year, some in the research community were surprised when Trump’s EPA backed the rule.
DCM is often used as a solvent in chromatography and as a reaction medium, due to its polarity, low boiling point and low flammability. These uses of the chemical are exempt under the new EPA ban, but the workplace requirements now in place are so onerous that many labs may choose to substitute the solvent altogether.
Overlapping and conflicting regulations
Federal and non-federal laboratories in the US, including many university and private research facilities, will have to put in place initial DCM exposure monitoring by 9 November 2026. And they must ensure that they are meeting the EPA’s new exposure limit of 2ppm over eight hours by 8 February 2027. That new standard appears to supersede the significantly laxer limit of 25ppm that the Occupational Safety and Health Administration (Osha) has had in place for almost three decades.
The EPA is also specifying a DCM ‘action’ level of above 1ppm that will force employers to implement controls that will lower worker exposure and conduct further evaluation. If that action level is surpassed, which compares to 12.5ppm under the existing Osha rules, then monitoring must be repeated every six months. If the action level of 1ppm is not breached labs can monitor once every five years, provided there are no equipment or process changes.
‘It’s not as if there wasn’t already some oversight and guidelines around the use of DCM as a laboratory chemical,’ explains Robert Clark, director of environmental health and safety at the University of Memphis in Tennessee who also does private environmental, health and safety consulting.
These overlapping and conflicting government agency regulations create an especially precarious situation for academic research institutions, Clark suggests. Universities use chemicals on a much smaller scale than industry, but they use a wider variety of chemicals than a typical manufacturer, he says.
Increased expenses anticipated
Clark anticipates that these rules will increase costs for labs at his institution and other universities, and notes that his institution had to pass on those expenses. ‘The way we approached it at the University of Memphis was that if researchers are going to continue to use DCM, then we will provide the labour for free, but they have to cover the lab analysis,’ he explains.
If the sampling can be done in-house, and the lab stays below the EPA’s new DCM exposure limits and, therefore, monitoring is only required every five years, the expense could be anywhere from $100 (£75) to a few thousand dollars per sample, Clark estimates. But some universities – particularly smaller ones – may not have an expert to handle DCM sampling so a consultant might be needed and that could cost several thousand dollars per analysis, he adds.
Tim Barton, chief safety officer at the University of Tennessee Health Science Center, says his university has spent considerable time and effort addressing the new rules. First, there was an inventory review to determine how much DCM was in stock, which labs housed the chemical and how it was being used. Then, exposure groups were identified, monitoring was conducted and the results were evaluated. Finally, this information was compiled into a brand-new detailed exposure control plan.
By 10 May 2027, labs are required to fully implement DCM exposure control plans. These must identify the measures in place to mitigate DCM contact and reduce inhalation exposure to acceptable levels.
A costly experience
‘It has been expensive and time consuming,’ Barton says, noting that funding for training and support had to be allocated. ‘We probably pulled about 20 samples at about $60 per sample… it diverted our resources away from other high priority activities,’ he states.
It appears that a significant number of academic researchers have elected to bin their DCM rather than submit to the EPA’s new rules. Clark estimates a 40% to 50% decrease in DCM use at University of Memphis organic chemistry labs since the regulations were first announced 18 months ago. However, he points out that university professors often hold on to chemicals unless there’s a cost associated with retaining them.
‘You had a number of researchers that had DCM maybe from 10 or 15 years ago and kept it just in case they needed it, and now they have gotten rid of it because there is no sense in paying for monitoring something that maybe they will use down the road,’ Clark states. In the meantime, he says the chemistry department at his university is searching for DCM substitutes, and this is no easy task.
Barton explains that DCM has been used to support a variety of process practices for a number of years, and identifying an alternative solvent is tricky. ‘One solvent might be good for one application whereas a different solvent might be good for another application – there is not a host of readily applicable alternatives that are appropriate for a wide range of uses.’
Overall, the rule has accelerated a transition away from DCM, especially where suitable alternatives already exist, according to the American Chemical Society (ACS). ‘Some teaching labs appear to be moving more quickly to eliminate DCM, while some industrial uses that EPA allowed to continue under strict workplace protections may take longer to transition,’ states Adelina Voutchkova, the ACS’s director of sustainable development. For universities, she says the practical effect is continued pressure to evaluate whether DCM is truly necessary, especially in teaching environments.
For chemical companies, Voutchkova suggests the deadline will push prohibited uses out of the market and reinforce the need to reformulate, substitute or redesign processes. When it comes to those firms in continuing-use categories, the emphasis is on stronger workplace protections, documentation and risk management, she adds.
Chemical companies that Chemistry World contacted either offered no response or declined to comment on the new EPA regulations. The American Chemistry Council, a trade group that represents US chemical companies, supports the rule and said it ‘allows for the continued use of methylene chloride in certain critical industrial and commercial applications, subject to stringent workplace protection requirements’. The organisation expressed its commitment, as well as that of its member companies, to the safe use of DCM in these applications.
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