Background workers at oil refineries and fuel installations have a high risk of exposure to benzene. Exposure to benzene can be determined by measuring benzene metabolites. s-Phenylmercapturic acid (sPMA) is a specific metabolite of benzene as a biomarker monitoring of workers exposed to benzene. This study aims to determine the differences in the levels of sPMA in urine refinery and fuel instalations respondents and factors associated with higher levels of sPMA.

Method This study was a cross-sectional comparative study, compare the levels of sPMA urine endshift. sPMA extracted from urine,analysed using Liquid Chromatography (LC). Samples selected by stratified proportional random sampling.

Result The total sample of 50 for each location. Levels of sPMA refinery respondents were in the range 2.82 to 489.12 ug/g creatinine with a median value 29.41 ug/g creatinine, whereas in the installation of the fuel is in the range from 0.45 to 58.47 ug/g creatinine with a median value of 3.10 ug/g creatinine. Levels of sPMA was significantly related to length of exposure per day, type of work (ORc = 2,72; 95% CI: 1,175–6,318), location of work (ORAd = 10,59; 95% CI: 3,481–32,207) and other sources of exposure outside of work (ORAd = 3,02; 95% CI: 1,103–8,253) while nutritional status, smoking and the use of PPE mask no association with levels of sPMA urine.

Conclusion There are differences of sPMA level in urine between the installation of fuel workers and refinery workers. Refinery workers have ten times higher risk of getting urinary levels of sPMA on the value of BEI (Biological Exposure Index) compared to workers in the fuel installation. 62% of respondents in the refinery and 12% of respondents in the installation of the fuel had higher levels of urinary sPMA above the BEI value.