Assessment of trans, trans-muconic acid in human seminal plasma

Trans, trans-muconic acid (tt-MA) is one of the most important metabolites of benzene, a pollutant ubiquitously distributed in ambient air and classified in 1982 as a group I carcinogen. For its sensitivity and specificity, tt-MA excreted in urine is considered a good biological marker of benzene exposure. In this study, seminal tt-MA levels in occupationally nonexposed subjects (n = 32) have been determined. The seminal fluid of normozoospermic subjects contained an average tt-MA concentration (170 +/- 100 ng ml-1) significantly lower than that of teratozoospermic (310 +/- 180 ng ml-1; P < 0.01), oligozoospermic (400 +/- 180 ng ml-1; P < 0.001), and oligoasthenozoospermic (430 +/- 230 ng ml-1; P < 0.01) subjects. A negative correlation existed between tt-MA levels and sperm concentration (r = - 0.62; P < 0.001), percentage of normal spermatozoa (r = - 0.41; P < 0.05), and percentage of vital spermatozoa (r = - 0.89; P < 0.001). Average tt-MA levels detected in seminal plasma were higher in smokers (350 +/- 160 ng ml-1) than in nonsmokers (280 +/- 210 ng ml-1). These results show that seminal plasma tt-MA content could be an important biological indicator for evaluating the negative effects of benzene on spermatogenesis.