Derivation of Navy Occupational Exposure Limits (OELS) for Two Solvent Compounds: Vertrel MCA and HFE-71DE

Abstract

Abstract:Currently, the US Navy uses the solvent HFC-14lb to clean hydraulic gauges in a semiclosed system prior to gauge calibration. The US Navy will not be able to use the solvent HFC141b after 31 December, 2002, because of a ban on its manufacture. The Navy is considering both Vertrel MCA and HFE-71DE as replacements for HFC-141b. Both solvents are azeotropic mixtures consisting of trans 1,2-DCE and either fluorocarbons or ethers. Both Vertrel MCA and HFE-71DE have high vapor pressures, therefore, they are expected to volatilize at room temperature. The potential routes of exposure to solvent during the gauge cleaning process are inhalation of vapors and dermal contact with liquid when pouring new and spent solvents into flasks and containers. At this time, toxicity information is not available for the azeotropic mixtures Vertrel MCA and HFE-71DE. It was decided that the human NOEL data for trans 1,2-DCE is the most appropriate toxicity data for deriving OEL's for Vertrel MCA and HFE-71DE. OEL's were derived using procedures recommended by the National Research Council. The NOEL of 800 ppm trans 1,2-DCE in air for an exposure time of 30 minutes was used as the endpoint for deriving 5, 10, 30, 60, 90, 120, 240, and 480-minute OEL's for Vertrel MCA and HFE-71DE. The derived OEL's for Vetrel MCA and HFE-71DE range between 48 for 5 minute exposures to 0.5 ppm for 8 hour exposures. The derived OEL's for Vertrel MCA and HFE-7IDE are lower than the 8-hour TLV-TWA for trans 1,2-DCE of 200 ppm, but the conservative nature of the recommended OEL's reflect the lack of toxicity information for Vertrel MCA and HFE-71DE and their major ingredients. Naval Health Research Center/Toxicology endorses the use of personal protective equipment when handling or using these chemicals as recommended by Naval Environmental Health Center industrial hygienists.Background: