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.

An exposure assessment of hot-mix asphalt (HMA) paving workers was conducted to determine which of four exposure scenarios impacted worker exposure and dose. Goals of this report are to present the personal-breathing zone (PBZ) data, discuss the impact of substituting the releasing/cleaning agent, and discuss work practices that resulted in the highest exposure concentration for each analyte. One-hundred-seven PBZ samples were collected from HMA paving workers on days when diesel oil was used as a releasing/cleaning agent. An additional 36 PBZ samples were collected on days when B-100 (100% biodiesel, containing no petroleum-derived products) was used as a substitute releasing/cleaning agent. Twenty-four PBZ samples were collected from a reference group of concrete workers, who also worked in outdoor construction but had no exposure to asphalt emissions. Background and field blank samples were also collected daily. Total particulates and the benzene soluble fraction were determined gravimetrically. Total organic matter was determined using gas chromatography (GC) with flame ionization detection and provided qualitative information about other exposure sources contributing to worker exposure besides asphalt emissions. Thirty-three individual polycyclic aromatic compounds (PACs) were determined using GC with time-of-flight mass spectrometry; results were presented as either the concentration of an individual PAC or a summation of the individual PACs containing either 2- to 3-rings or 4- to 6-rings. Samples were also screened for PACs containing 4- to 6-rings using fluorescence spectroscopy. Arithmetic means, medians, and box plots of the PBZ data were used to evaluate trends in the data. Box plots illustrating the diesel oil results were more variable than the B-100. Also, the highest diesel oil results were much higher in concentration than the highest B-100 results. An analysis of the highest exposure results and field notes revealed a probable association between these exposures and the use of diesel oil, use of a diesel-powered screed, elevated HMA paving application temperatures, lubricating and working on broken-down equipment, and operation of a broom machine.

Evaluation of a new enzyme-linked immunosorbent assay for detection of Chagas antibody in US blood donors.

BACKGROUND: Chagas disease, caused by the parasite Trypanosoma cruzi, represents a serious blood safety problem due to increasing immigration from Latin America. The Food and Drug Administration recently recommended implementation of Chagas antibody screening for US donors as soon as a suitable assay is licensed. An anonymized preclinical study of a prototype T. cruzi lysate-based enzyme-linked immunosorbent assay (ELISA) developed by Ortho-Clinical Diagnostics was conducted. STUDY DESIGN AND METHODS: Two populations of specimens were evaluated: 1) 10,192 sequential donations from blood donors residing in the El Paso, Texas, area and 2) 178 specimens from South America which were presumptively positive for antibodies to T. cruzi and purchased from commercial vendors. RESULTS: A total of 10,189 (99.97%) of the 10,192 screened donor specimens did not react, whereas 3 (0.03%) tested initially reactive. The 3 initially reactive specimens tested repeat reactive and were confirmed by radioimmunoprecipitation analysis (RIPA). Based on antibody profile analysis, 2 of the 3 Chagas-positive specimens were from the same donor. Observed specificity of the test was therefore 100 percent. Of the specimens from South America, 173 of 178 were reactive by the prototype ELISA. Of the 5 nonreactive specimens, all did not react by indirect fluorescence assay, but 4 were positive by RIPA. Therefore, calculated sensitivity of the ELISA was 97.7 percent (173/177). CONCLUSIONS: These studies indicate that the prototype ELISA has excellent sensitivity and specificity for detection of antibodies to T. cruzi in donors. Moreover, among donations from a geographically selected collection region of the United States, observed seroprevalence was 0.03 percent.

Evaluation of worker exposure to asphalt paving fumes using traditional and nontraditional techniques.

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).