Exposure-response of asphalt fumes with changes in pulmonary function and symptoms

Objectives This study examines possible associations between asphalt fumes and workshift changes in lung function and symptoms among 170 workers expos ed to asphalt fumes. Methods The workers were from 5 segments of the asphalt industry, and most of them participated for 2 consecutive workdays. The primary response varia bles were changes in lung function (measured at the beginning and end of th e shift) and incidence of symptoms (measured before, 3 times during, and at the end of the shift). Exposure was estimated from breathing-zone samples of total particulate (TP), respirable particulate (RP), the benzene-soluble fraction of the TP (BSF), volatile hydrocarbons collected on a charcoal tu be (VHC), nitrogen dioxide, sulfur dioxide, formaldehyde, carbon monoxide, and hydrogen sulfide. Ozone and wet bulb/dry bulb temperature, as a measure of heat stress, were measured as area samples. In addition, daily cigarett e smoking was determined by questionnaire. The exposure-response associatio ns were assessed by both parametric and nonparametric statistical technique s. Results Overall, no consistent association was observed between an acute re duction in lung function or the incidence of symptoms and exposure to aspha lt fumes. Concentrations in the neighborhood of the maximum levels constitu te no-observed adverse effect levels: TP (<1.5 mg/m(3) to maximum 6.2 mg/m( 3)), RP (<0.6 mg/m(3) to maximum 1.4 mg/m(3)), BSF (<0.6 mg/m(3) to maximum 1.3 mg/m(3)), VHC (<8 mg/m(3) to maximum 19.8 mg/m(3)). There were no expo sure-response trends with ozone, heat stress, cigarettes smoked, or length of workday.