Dimethyl ether (DME)

The WEEL guide for dimethyl ether (DME) was originally established in 1996 and updated in 2010. Literature searches to identify new toxicity information were performed in November 2020 and evaluated by the WEEL Revisions Subcommittee. No new studies or data relevant to the WEEL guide were identified. DME has very low acute inhalation toxicity with a 4 h LC₅₀ in rats of 164,000 ppm, and a cardiac sensitization threshold in dogs of >200,000 ppm. In repeated inhalation studies of up to 2 years in the rat, DME was not carcinogenic and produced minimal toxicity at 25,000 and 10,000 ppm: the NOAEC was 2000 ppm. DME was not teratogenic in pregnant rats up to 40,000 ppm; slight maternal and fetal toxicity were observed at >5000 ppm. DME was not mutagenic in vitro or in vivo. The primary finding with inhalation exposure was a reversible CNS depression. Based on a clear NOAEC of 2000 ppm for all effects in a lifetime inhalation study in rats, and the general low level of toxicity found in acute and subchronic toxicity studies, a WEEL of 1000 ppm (v/v; 8-h time-weighted average) was reaffirmed in 2021 and should provide an adequate margin of safety.