Biological monitoring of vehicle mechanics and other workers exposed to low concentrations of benzene

Abstract

It has been suggested that the threshold limit value (TLV) for the time-weighted average (TWA), of benzene be lowered because of its possible leukemogenic effect at low exposure concentrations. This requires the development of new methods of biological monitoring. In this cross-sectional study the diagnostic power of blood and breath benzene and of urinary phenol, catechol, hydroquinone, S-phenylmercapturic acid, and muconic acid were compared in a population of 410 male workers exposed to benzene in garages, in two coke plants, and in a by-product plant. Benzene exposure was assessed by personal air sampling (charcoal tube and passive dosimeter). In all, 95% of the workers were exposed to less than 0.5 ppm benzene. According to the multiple regression equation, the muconic acid and S-phenylmercapturic acid concentrations detected in nonsmokers exposed to 0.5 ppm benzene were 0.3 mg/g and 6 micrograms/g, respectively (range 0.2-0.6 mg/g and 1.2-8.5 micrograms/g, respectively). With muconic acid very few false-positive test results were found, and this determination remained reliable even around a cutoff level of 0.1 ppm benzene. Moreover, the diagnostic power of this test proved to be good even when diluted or concentrated urine samples were not excluded. S-Phenylmercapturic acid (S-PMA) also performed fairly well. Blood and breath benzene as well as urinary phenol (PH) and hydroquinone (HQ) were clearly less suitable biomarkers than muconic acid (MA). Catechol (CA) was not associated with occupational benzene exposure. According to the results of biological monitoring, the skin resorption of benzene from gasoline or other fuels seems negligible. Correlation, multiple regression, and likelihood ratios consistently showed that MA and S-PMA concentrations were fairly good indicators of benzene exposure in the 0.1- to 1-ppm range, even in a population comprising both smokers and nonsmokers. PH, HQ, CA, and blood and breath benzene were less suitable, if at all, in the same exposure range.

Urinary Phenylmercapturic Acid as a Marker of Occupational Exposure to Benzene.

“…Nevertheless, the observation as a whole suggests that the effect should be small if present. Thus, the present survey not only supports the opinion that PMA is a good biomarker of benzene exposure 8,9,[15][16][17][18][19] , but has demonstrated that PMA is useful even under the condition of co-exposure to other aromatics and most probably to other solvents in general. The latter observation suggests that, as a benzene exposure marker, PMA is superior to mono-to tri-hydroxylated benzenes [phenol 27) , quinol 27) and catechol 27) , 1,2,4-benzenetriol 11) ] and t,t-muconic acid 13) , because the excretion of these urinary benzene metabolites other than PMA are all known to be suppressed by coexposure to other aromatics.…”

“…Major findings available in literature on quantitative relationship of PMA in end-of-shift urine with TWA benzene exposure 8,9,[15][16][17][18][19] are summarized in Table 4. The reported values for PMA corresponding to 1 ppm benzene cluster around 40 µg/g cr with two extremes of 12 and 58 µg/g cr.…”

“…in terms of increased incidence of leukemia among benzeneexposed industrial workers [3][4][5] , benzene is present in automobile gasoline 6,7) , and is in use in organic synthesis in modern industries. Benzene exposure in cokeries in the iron and steel industry is also known 8,9) . This study group has been studying on urinary biomarkers of occupational exposure to benzene such as catechol 10) , quinol 10) , 1,2,4-benzenetriol 11,12) as well as t,t-muconic acid 13) in addition to a traditional marker of phenol 14) .…”

“…This study group has been studying on urinary biomarkers of occupational exposure to benzene such as catechol 10) , quinol 10) , 1,2,4-benzenetriol 11,12) as well as t,t-muconic acid 13) in addition to a traditional marker of phenol 14) . Urinary phenylmercapturic acid (PMA; N-acetyl-S-phenyl-L-cysteine), a N-acetylcysteine conjugate of benzene, has also been evaluated as a marker of exposure to low-level benzene 8,9,[15][16][17][18][19][20] , but the analytical methods employed are rather complex, e.g., requiring derivatization or clean-up through columns before instrumental analysis [21][22][23][24][25] such as gas chromatography-mass spectrometry 15) or liquid chromatography-mass spectrometry 26) , and application of the methods to routine occupational health services appear to be not practical.…”

A battery of DNA effect biomarkers to evaluate environmental exposure of Flemish adolescents

“…A modified Ducos et al (1990) method was used to quantify t,t′-muconic acid in urine. The detection limit was 0.02 mg l −1 (Hotz et al, 1997). Ortho-cresol in urine was determined by gas chromatography with flame ionization detection (Pierce et al, 1998;Truchon et al, 1999).…”