Evaluation of Worker Exposure to Asphalt Paving Fumes Using Traditional and Nontraditional Techniques

Abstract

Forty-five workers at 11 paving sites across the United States were evaluated for exposure to paving asphalt (bitumen) fumes. Traditional measures of exposure such as total particulate matter (TPM) and benzene soluble matter (BSM) were monitored. In addition, total organic matter (TOM), which includes both the BSM residue and the more volatile components that pass through the filter and are collected on sorption material, was quantified and further characterized using a gas chromatography technique and a recently developed fluorescence test. The latter method, which indirectly estimates the content of four- to six-ring polycyclic aromatic compounds, is used as a predictor of carcinogenicity. The correlation between fluorescence emission intensity and carcinogenicity for 36 laboratory generated fume fractions, as measured in a mouse skin-painting bioassay, was then used to estimate the carcinogenic potential of worker monitoring samples. Emission levels, and therefore predicted carcinogenicity, for these samples were at least 17-fold below the value corresponding to a minimal carcinogenic effect. This result was consistent with more extensive chemical analysis (using gas chromatography/mass spectrometry) of two of the samples, which showed the predominant constituents to be alkanes, monocycloparaffins, alkyl-benzenes, alkyl-naphthalenes, and alkyl-benzothiophenes. The geometric mean exposures for all worker studies were 0.21 mg/m3 (TPM), 0.06 mg/m3 (BSM), and 1.23 mg/m3 (TOM).

Life Cycle Assessment of Pavements: A Critical Review of Existing Literature and Research

“…A 2002 study in the United States measured PAH levels for 45 workers across 11 paving sites [127]. Carcinogens were found in the fumes, but at a level 17 times lower than the value corresponding to the minimal carcinogenic effect.…”

Personal Breathing Zone Exposures among Hot-Mix Asphalt Paving Workers; Preliminary Analysis for Trends and Analysis of Work Practices That Resulted in the Highest Exposure Concentrations

“…Kriech et al (21) data show TOM = 1.23 mg/m 3 and Kriech et al (26) data show TOM = 1.41 mg/m 3 ; for both studies, the arithmetic mean HMA paving application temperature was 150°C. In the current study, the arithmetic mean data show TOM = 1.03 mg/m 3 at an arithmetic mean HMA paving application temperature of 139°C for diesel oil use.…”

“…Over the time period that these studies were conducted (i.e., 1998-2008), the arithmetic mean HMA paving application temperatures have decreased, supporting claims by industry that application temperatures are being lowered, when possible, as recommended by NIOSH. (2) Averaging the TOM exposure data from the two earlier studies (21,26) (1.32 mg/m 3 ) and comparing the result to our TOM exposure data for when diesel oil was used shows an estimated TOM reduction of 22% and corresponds to an HMA paving application temperature decrease of ~11°C.…”

“…Typical paving emissions yield low fluorescence results because they contain little if any PACs containing 4-to 6-rings. (21) An important distinction between the fluorescence method and the speciation of individual PACs by GC/TOFMS is that the fluorescence response also includes alkylated PACs that tend to be more prominent than their parent structures in these emissions. (21) PBZ exposure data were summarized in box plots and individual data provided in supplemental tables.…”

“…(21) An important distinction between the fluorescence method and the speciation of individual PACs by GC/TOFMS is that the fluorescence response also includes alkylated PACs that tend to be more prominent than their parent structures in these emissions. (21) PBZ exposure data were summarized in box plots and individual data provided in supplemental tables. Results were summarized separately for the HMA paving group using either diesel oil or B-100 as a releasing/cleaning agent, for the reference group, and for the background samples and field blanks.…”