Exposure of Workers Engaged in Furniture Stripping to Methylene Chloride as Determined by Environmental and Biological Monitoring

Abstract

In response to reports of adverse reproductive effects of exposure to methylene chloride, investigators from the National Institute for Occupational Safety and Health conducted an industrial hygiene survey of a cohort of 14 furniture strippers exposed to methylene chloride in five furniture stripping shops. Both environmental and biological monitoring of the workers were conducted. Personal time-weighted average (TWA) concentrations of methylene chloride were determined. Pre- and postshift alveolar breath samples were analyzed for carbon monoxide and methylene chloride. Postshift venous blood samples were analyzed for carboxyhemoglobin and methylene chloride. Methylene chloride TWA exposures of the workers ranged from 15 to 366 ppm, while exposures to other solvents were well below their respective evaluation criteria. The highest average exposures to methylene chloride by job category were strippers (191 ppm) followed by washers (145 ppm) and refinishers (31 ppm). Postexposure breath concentrations of methylene chloride ranged from 2.3 to 167 ppm, while blood concentrations ranged from 0.1 to 8.8 ppm. Linear regression analysis showed that the TWA methylene chloride exposure concentrations were quadratically correlated to postshift alveolar breath (r = 0.98) and blood concentrations (r = 0.87) of methylene chloride. This high degree of correlation between the biological and environmental concentrations suggested that the major route of exposure was inhalation. Serious problems with ventilation of sprayer-based furniture stripping operations were found. Deficiencies in work practices and personal protective equipment were also noted. Recommendations are made for reducing exposures to methylene chloride during furniture stripping.