Original ArticleCarboxyhemaglobin Levels in Methylene Chloride-Exposed EmployeesSoden, Kevin J. MD; Marras, Gilbert MD; Amsel, Jonathan ScDAuthor Information From the Fibers and Film Group, Hoechst Celanese Corporation, Charlotte, North Carolina (Dr Soden); Hoechst Celanese N.V., Lanaken, Belgium (Dr Marras); and Hoechst Celanese Corporation, Somerville, New Jersey (Dr Amsel). Address correspondence to: Kevin J. Soden, MD, Medical Director, Fibers and Film Group, Hoechst Celanese Corporation, 5200 77 Center Drive, PO Box 1026, Charlotte, NC 28201-1026. Journal of Occupational & Environmental Medicine: April 1996 - Volume 38 - Issue 4 - p 367-371 Buy Abstract The Occupational Safety and Health Administration (OSHA) has proposed a reduction in the permissible exposure limit for methylene chloride from 500 parts per million (ppm) to 25 ppm (8-hour time-weighted average [TWA]). Part of the rationale for lowering the standard is a concern over potentially adverse cardiac effects secondary to elevated carboxyhemoglobin (COHb) levels as a byproduct of methylene chloride metabolism. Employees exposed to methylene chloride as part of a triacetate fiber production process had average values of COHb ranging between 1.77% and 4.00% in the nonsmoking group and between 4.95% and 6.35% in a smoking group, with individually measured methylene chloride exposures averaging up to 99 ppm (8-hour TWA). A dose-response effect was seen only in the nonsmoking group. Additional daily cumulative exposure to methylene chloride did not produce increased levels of COHb. Data from this study support the fact that the COHb levels resulting from exposure to methylene chloride at or below the current American College of Government Industrial Hygienists limit of 50 ppm (8-hour TWA) are of a sufficiently low level that they are unlikely to produce adverse cardiac effects in humans. © Williams & Wilkins 1996. All Rights Reserved.