Atmospheric Benzene and Determination of Trans, Trans-Muconic Acid of Workers at Oil Sites in Pointe-Noire

Trans, trans-muconic acid is generally considered a useful biomarker of exposure to benzene that occurs naturally in crude oil.

Objective: To estimate exposure of benzene to workers in an oil and gas production company.

Materials and Methods: Firstly, it was a descriptive, cross-sectional study which consisted of benzene atmospheric quantification in a sample individual measurements of a homogeneous exposure group of workers. Secondly, urinary assays of trans, trans-muconic acid have been performed at the end of the shift in the selected workers.

Results: A total of 79 (47.88%) workers agreed to participate in the study. Seventeen atmospheric samples were usable and 79 urinary assays at the end of the shift were carried out. The average benzene concentration for all sites was 10 times lower than the regulatory average exposure value (1 ppm=3.25 mg/m3):average: 0.122pp, median: 0.053ppm and range: 0.019-1.448 ppm. All 79 urinary assays of trans, trans-muconic acid were below the biological exposure index (<500 µg/g creatinine) with an average of 37.34 µg/g creatinine, a median of 30 µg/g creatinine, and an extent from 10 to 150 µg/g creatinine.

Conclusion: Airborne benzene concentrations were below company limits. The same was true for the urinary assays of trans, trans-muconic acid. Overall, therefore, exposure to benzene is low in this company. However, there is a need to maintain regular medical surveillance as the risk of exposure is ongoing.