Validation of a radial diffusive sampler for measuring occupational exposure to 1,3-butadiene

Abstract

1,3-Butadiene (BD) is a major industrial chemical used in the manufacture of rubbers and latexes; it is also a ubiquitous environmental pollutant whose major source is traffic. Occupational exposure to (BD) can occur both during its production and during its use as a raw material. The objective of the study was the laboratory and field validation of a new diffusive sampler for BD. The nominal sampling rate of the Radiello® diffusive sampler filled with Carbopack X is 30.5cm3/min, at 0.177mg/m3, 20°C and 50% relative humidity (RH), for an 8-h exposure time. A model can be used for calculating the sampling rate as a function of temperature, time and RH. The concentration does not affect the sampling rate above 30μg/m3. The measurement uncertainty (k=2), calculated both by laboratory data and by field comparison according to International Standard Organization (ISO) 13752, satisfies the EN 482:2006 requirement for measurements between 0.1 and 0.5 times the threshold limit value—time weighted average (TLV–TWA) (uncertainty<50%). For field validation study, 38 workers exposed to BD and 20 administrative employees, as the control group, underwent environmental and biological monitoring. Personal exposure to BD was measured by diffusive samplers (Radiello®) in comparison with active samplers. The BD exposure levels detected for the exposed subjects were low (mean 0.059, range <0.010–1.340mg/m3) but higher than the controls levels, all below 0.010mg/m3. The comparison between diffusive and active (pumped) air sampling showed a good correlation, with no systematic deviation from the ideal values of the intercept and slope of the optimized regression line. The concentrations of two biomarkers were also determined on urine samples, collected at the end of the work-shift: unchanged BD, by GC–MS, and the metabolite dihydroxybutylmercapturic acid (DHBMA), by HPLC–MS/MS. The urinary excretion of the biomarkers was on average higher in the exposed group (urinary BD: mean 8.8, range <1–48.1ng/l; DHBMA: mean 0.232, range 0.016–0.572mg/l) than in controls (urinary BD: mean 6.4, range 2.6–14.5ng/l; DHBMA: mean 0.205, range 0.037–0.602mg/l), but a statistically significant difference was achieved only for unchanged BD and not for DHBMA. In conclusion, the environmental monitoring measured by diffusive samplers (Radiello®) appears to be a reliable method for the assessment of exposure to low levels of airborne BD and a convenient alternative to the conventional active sampling.