DBE purges polyurethane equipment without methylene chloride risks

204 8.8 hen using a cast polyurethane processW ing machine, purging o r flushing the mixing head a t frequent intervals is required. Over the years the standard method of purging has been to blow out most of the polyurethane with air or nitrogen followed by pumping through a solvent. The favored solvent for purging has been methylene chloride (MeCI), which functions well technically. Recently, results of laboratory studies have questioned the human safety of using methylene chloride. Consequently, methylene chloride is under review by state and federal asencies. Some agencies already have implemenied regulations, while others are pending. A study showing that methylene chloride caused tumors in rats and cancer in mice was published by the National Toxicology Program in 1985. As a result, the Environmental Protection Agency (EPA), the Occupational Safety and Health Administration (OSHA), the Con-