Biological monitoring of low benzene exposure in Italian traffic policemen.

A comparative evaluation of urinary biomarkers was carried out to characterize benzene exposure in a
group of 100 traffic policemen of the city of Parma (Italy). All subjectswere monitored once, in two consecutive
days characterized by similar climatic conditions but preceded by two windy days. Benzene ambient
concentration measured by municipal air monitoring stations was 1g/m3 (Day 1) and 2g/m3 (Day 2).
Personal exposure to ambient concentrations of benzene, toluene, ethylbenzene and xylene (BTEX) was
assessed by using Radiello® passive-diffusive samplers in a subgroup of 24workers. Benzene metabolites,
t,t-muconic acid (t,t-MA) and S-phenylmercapturic acid (S-PMA) were determined by isotopic dilution
liquid chromatography–tandem mass spectrometry on spot urine samples collected at the end of the
shift. Urinary benzene (U-B) was determined by solid-phase microextraction gas chromatography–mass
spectrometry. Airborne benzene concentration expressed as median [and interquartile range] was 6.07
[0.28–9.53]g/m3, as assessed by personal sampling. Urinary concentrations of biomarkers in the whole
group were 41.8 [34.1–89.8]g/g creatinine for t,t-MA, 0.67 [0.23–1.32]g/g creatinine for S-PMA, and
0.16 [0.13–0.26]g/l for U-B. Smokers eliminated significantly higher concentrations of unchanged BTEX
and benzene metabolites than non-smokers (p < 0.05). When traffic policemen were distinguished into
indoor (n = 31) and outdoor workers, no significant differences were observed for either airborne benzene
or urinary biomarkers. Significantly lower concentrations of S-PMA and U-B were determined in samples
collected at Day 1 as compared to Day 2 (p < 0.0001 and p = 0.003, respectively) suggesting that these
biomarkers are enough sensitive and specific to detect changes in airborne benzene concentration even
at few g/m3.