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

MATERIALS Pavement Core Samples COAL TAR AND ASPHALT CEMENT SAMPLES METHODS OF ANALYSIS Binder Content PAH Analysis Analysis of Phenols Modified Ames Assay RESULTS Coal Tar and Asphalt Cement Core Sample Analyses COMPARISON OF CORE SAMPLES WITH U.S. AND EUROPEAN ASPHALT AND COAL TARS COMPARISON OF DIN METHOD FOR PHENOLS WITH THE CORE SAMPLES COMPARISON OF MODIFIED AMES TEST RESULTS DISCUSSION CONCLUSIONS REFERENCES LIST OF TABLES TABLE 1 Copenhagen mastic asphalt pavement core samples TABLE 2 Analytical comparison of selected core samples with standard asphalt and coal tar products TABLE 3 Analyses of Danish mastic asphalt pavement core samples LIST OF FIGURES FIGURE 1 Mastic Asphalt Paving in Copenhagen (1953) FIGURE 2 City of Copenhagen Asphalt Pavement Core Samples ABSTRACT Recent reports have linked exposure to asphalt fumes to higher incidences of cancer in workers employed in mastic asphalt pavement operations in Denmark. The conclusion that asphalt fume exposure was responsible for the excess cancers rests heavily on the proper connection for and/or absence of confounding exposures particularly to coal tar fumes. Coal tar was known to be used in paving in Denmark prior to and during World War II. However, there has been significant debate about when its use was discontinued. This study looked at potential methods for detecting coal tar in historically dated pavements placed in the city of Copenhagen. The study found that there are clear chemical marker compounds and tests which 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. The results of the study show that coal tar usage in Denmark extended up until at least 1970.Recent reports have linked exposure to asphalt fumes to higher incidences of cancer in workers employed in mastic asphalt pavement operations in Denmark. The conclusion that asphalt fume exposure was responsible for the excess cancers rests heavily on the proper connection for and/or absence of confounding exposures particularly to coal tar fumes. Coal tar was known to be used in paving in Denmark prior to and during World War II. However, there has been significant debate about when its use was discontinued. This study looked at potential methods for detecting coal tar in historically dated pavements placed in the city of Copenhagen. The study found that there are clear chemical marker compounds and tests which 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. The results of the study show that coal tar usage in Denmark extended up until at least 1970.