Biological monitoring of exposure to benzene: a comparison between S-phenylmercapturic acid, trans,trans-muconic acid, and phenol.

Abstract

Objectives-Comparison of the suitability of two minor urinary metabolites of benzene, trans,trans-muconic acid (tt-MA) and S-phenylmercapturic acid (S-PMA), as biomarkers for low levels of benzene exposure. Methods-The sensitivity of analytical methods of measuring tt-MA and S-PMA were improved and applied to 434 urine samples collected from 188 workers in 12 studies in different petrochemical industries and from 52 control workers with no occupational exposure to benzene. In nine studies airborne benzene concentrations were assessed by personal air monitoring. Results-Strong correlations were found between tt-MA and S-PMA concentrations in samples from the end of the shift and between either of these variables and airborne benzene concentrations. It was calculated that exposure to 1 ppm (8 hour time weighted average (TWA)) benzene leads to an average concentration of 1'7 mg tt-MA and 47 jg S-PMA/g creatinine in samples from the end of the shift. It was estimated that, on average, 3 9%/6 (range 1.90/o-7.3%) of an inhaled dose of benzene was excreted as tt-MA with an apparent elimination half life of 5*0 (SD 2.3) hours and 0*11% (range 0-050/%0-26%) as S-PMA with a half life of 9 1 (SD 3.7) hours. The mean urinary S-PMA in 14 moderate smokers and 38 non-smokers was 3*61 and 1*99 uglg creatinine, respectively and the mean urinary tt-MA was 0 058 and 0 037 mglg creatinine, respectively. S-PMA proved to be more specific and more sensitive (P = 0-030, Fisher's exact test) than tt-MA. S-PMA, but not tt-MA, was always detectable in the urine of smokers who were not occupationally exposed. S-PMA was also detectable in 20 of the 38 nonsmokers from the control group whereas tt-MA was detectable in only nine of these samples. The inferior specificity of tt-MA is due to relatively high background values (up to 0'71 mglg creatinine in this study) that may be found in non-occupationally exposed people. Conclusions-Although both tt-MA and S-PMA are sensitive biomarkers, only S-PMA allows reliable determination of benzene exposures down to 0 3 ppm (8 h TWA) due to its superior specificity. Because it has a longer elimination half life S-PMA is also a more reliable biomarker than tt-MA for benzene exposures during 12 hour shifts. For biological monitoring of exposure to benzene concentrations higher than 1 ppm (8 h TWA) tt-MA is also suitable and may even be preferred due to its greater ease of measurement. (Occup Environ Med 1995;52:611-620)

Dermal exposure assessment to benzene and toluene using charcoal cloth pads

“…Hence, the estimated contribution of the dermal route to internal benzene exposure, levels was less than 0.06% for all jobs. Although SPMA is thought to be one of the most sensitive markers for benzene exposure it is only able to reliably detect inhalation exposure levels down to 1 mg/m 3 (8-h time-weighted average) (Boogaard and van Sittert, 1995).…”

Avaliação da exposição ocupacional ao benzeno em trabalhadores frentistas e analistas de combustíveis utilizando o Teste Cometa como biomarcador de genotoxicidade

“…No Grupo II, os valores encontrados de AttM urinário são similares a valores reportados na literatura, que foram de <0,01-0,66 mg/g de creatinina 28,39,40 , considerando os diversos fatores que influenciam a concentração do AttM na urina, como tabagismo, o consumo de ácido sórbico e seus sais presentes em alguns alimentos, álcool, além de fatores individuais. Para diminuir os fatores de confusão, foram excluídos deste estudo os indivíduos fumantes e um questionário detalhado foi aplicado em ambos os grupos.…”

A biomarker approach to estimate the daily intake of benzene in non-smoking and smoking individuals in Germany

“…A short metabolism scheme of benzene is shown in Figure 1. The elimination half-life of urinary S-PMA after exposure to benzene is considerably longer than that for t,t-muconic acid and has been determined to be 9.1 ( ± 3.7) hours (Boogaard and van Sittert, 1995).…”

“…Fractional UE data were provided by occupational studies where both personal air monitoring of benzene and UE of S-PMA was determined. The fraction of inhaled benzene excreted as S-PMA was calculated to be 0.0011 in the mean (Boogaard and van Sittert, 1995), ranging from 0.0005 to 0.0026. This is in good agreement with the data of Kim et al (2006) who reported an F UE for S-PMA below 0.01 without giving exact data.…”