Biological monitoring of styrene exposure and possible interference of acetone co-exposure

Abstract

The object of this study is the evaluation of some of the toxicokinetic effects of exposure to low concentrations of styrene, and the possible influence of simultaneous exposure to acetone. To this end we studied 19 workmen simultaneously exposed to both solvents. During a week of 4-h work shifts, the workmen underwent daily personal environmental monitoring and the collection of urine samples, at both the beginning and the end of the work period, for the determination of mandelic acid (MA) and phenylglyoxylic acid (PGA). The presence of the solvents in the atmosphere was evaluated using passive personal monitoring and gas chromatography. Average exposure to styrene and acetone were respectively 72.2 mg/m3 and 225.7 mg/m3. MA and PGA were quantified by high-performance liquid chromatography (HPLC). The daily urinary concentration averages, both at commencement and at the end of work shifts, of both the metabolites studied and of the sum of the two were in statistically significant linear correlation with the average daily styrene exposure. Concentrations of MA and PGA in urine samples collected at the start of the work shift averaged 61.5 mg/g creatinine and 45.2 mg/g creatinine respectively, representing 41% and 72% of those at the endo of the work shift which were 148.3 and 62.6 mg/g creatinine, respectively. With equal exposure to styrene, the average urinary concentrations of MA and PGA at both the beginning and end of the work shift increased significantly (P < 0.001) during the working week. Moreover, we found that with equal exposure to styrene, urinary excretion of MA, PGA and MA + PGA at the end of the shift was inversely correlated with the intensity of acetone exposure (r = 0.4659, 0.3410 and 0.542 respectively, P < 0.001). In conclusion, these results express slower urinary kinetics of styrene metabolites than is usually described in the literature, and favor a tendency to accumulate MA and PGA in the organism as a consequence of the retardation of urinary excretion kinetics. Acetone apparently represents one of the determining factors in this interference.

Inter- and intra-individual sources of variation in levels of urinary styrene metabolites

“…Our data also con®rm previous ®ndings (Sollenberg et al 1988;Imbriani et al 1990;Marhuenda et al 1997) of higher styrene metabolite levels towards the end of the workweek. Thus, information about the timing of sampling should be ascertained when evaluating dierences in metabolite levels from one time period to another or between dierent groups of workers, to ensure that valid comparisons are made.…”

“…Others, such as alcohol consumption (Wilson et al 1983;Berode et al 1986;Cerny et al 1990), co-exposure to other solvents (Marhuenda et al 1997;Apostoli et al 1998), and workload (Pezzagno et al 1988) may interfere with styrene metabolism or aect absorption. Unfortunately, data on these variables were not available, so it was not possible to evaluate their roles in explaining the variation in urinary metabolite levels.…”

“…Among the biological monitoring methods available, measurements of urinary MA and PGA are the most commonly used biological indices of exposure to styrene. Numerous investigations have focused on the relationship between these metabolites with airborne styrene concentrations or on their relationship with each other (EngstroÈ m et al 1976;Guillemin et al 1982;Ikeda et al 1982;Apostoli et al 1983;Franchini et al 1983; Bartolucci et al 1986;De Rosa et al 1988;Imbriani et al 1990;Brenner et al 1991;Galassi et al 1993;Pekari et al 1993;Marhuenda et al 1997;Ghittori et al 1997;Apostoli et al 1998). Despite the considerable attention that MA and PGA have received in the literature, we are aware of no study that has quanti®ed the sources of variation in levels of these two biomarkers among workers exposed to styrene.…”

Biological monitoring for exposure to volatile organic compounds (VOCs) (IUPAC Recommendations 2000)

“…Field studies for effects on VOC metabolism after combined exposure mostly for aromatic hydrocarbons [107][108][109][110][111][112][113][114] are summarized in Table 10. Table 9 Experimental exposure of volunteers to solvent mixtures: effects on metabolism [98] (either the maximum non-effective dose or the minimum effective dose is given when two or more concentrations were tested).…”

Optimization and Application of the Head Space Liver S9 Equilibration Technique for Metabolic Studies of Organic Solvents

“…1993). However, Marhuenda et al (1997) showed that the urinary excretion of styrene metabolites (mandelic acid and phenylglyoxylic acid) during 4 hr work shifts was inversely correlated with the intensity of acetone exposure. Whether acetone during short-term exposure is able to interact with the metabolism of styrene therefore needs more research.…”