Comparison of Field- and Laboratory-Generated Asphalt Fumes

Studies conducted by the National Institute of Occupational Safety and Health (NIOSH) evaluated the carcinogenicity of fumes collected from a catalytically prepared roofing asphalt at 232°C and 316°C using a laboratory generator. The fume condensate from these studies was found to cause a carcinogenic response. However, the uniqueness of the roofing asphalt and the laboratory-generation method makes it difficult to assess the meaning of this study in the context of paving asphalt. Fumes from paving asphalt operations were compared compositionally with the fumes generated and used in the NIOSH animal studies. In addition, the impact of temperature on asphalt fume composition was examined. The results showed that fume composition is greatly affected by the conditions under which the fume is generated, the design of the laboratory fume generator having the most significant effect on the type of fume produced. Fumes collected at field paving sites bear little resemblance chemically to the roofing fume used in the animal study. Most important, the compounds most likely responsible for the carcinogenicity in the animal studies were not present in fumes found in the field paving sites studied.