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.
La composizione chimica dei fumi provenienti dall’asfalto riscaldato risulta in un’eterogenea miscela comprendente, tra l’altro, combinazioni di idrocarburi policiclici aromatici e loro derivati eterociclici, la cui concentrazione può variare apprezzabilmente sulla base delle caratteristiche del greggio di provenienza e dei suoi processi di raffinazione.
Mentre la cancerogenicità derivante dall’esposizione professionale a queste emissioni resta sotto inchiesta da parte della IARC e del NIOSH, che ha pubblicato nel 2001 un’esauriente ricerca sull’argomento (“Hazard Review: Health Effects of Occupational Exposures to Asphalt”), gli effetti irritanti e le potenziali alterazioni della funzionalità polmonare sono stati largamente documentati nella comunità scientifica.
Nella presente ricerca, Osborn e collaboratori hanno condotto un’approfondita valutazione dell'esposizione professionale a fumi di asfalto in quattro differenti scenari lavorativi. Nell’analisi sono comprese anche le esposizioni provenienti dal gasolio, largamente utilizzato per le procedure di pulizia degli strumenti e dei macchinari.