Detection of Coal Tar Materials in Asphalt Pavements by Using Chemical and Biological Methods

Recent reports have linked exposure to asphalt fumes to higher rates of cancer in workers employed in mastic asphalt pavement operations in Denmark. The conclusion that asphalt fume exposure was responsible for cancer rests heavily on the proper connection for or the absence of confounding exposures, especially to coal tar fumes. Coal tar was used in paving in Denmark before and during World War II. However, significant debate has occurred about when its use was discontinued. Potential methods for detecting coal tar in historically dated pavements placed in the city of Copenhagen were examined. It was found that there are clear chemical marker compounds and tests that can determine the presence of coal tar materials in an asphalt aggregate mixture. The results of a short-term biological test called the modified Ames assay also correlated well with the presence or absence of coal tar–derived materials. Results show that coal tar usage in Denmark extended until at least 1970.