Effects of smoking on the levels of urinary biomarkers of aromatic hydrocarbons in oil refinery workers

Abstract

Occupational exposures to aromatic hydrocarbons may be overwhelmed by mainstream and secondary smoking exposures. The objective of this study was to evaluate the influence of occupational exposures and smoking on benzene and toluene urinary metabolites. The metabolites were measured in pre and post-work shift urine specimens in oil refinery workers by gas chromatography/ mass spectrometry techniques. Post-shift concentration differences between non-smokers and smokers were statistically significant (at p-value \ 0.05). Pre-and post-shift concentrations of urinary phenol (benzene biomarker) did not vary significantly for both non-smokers and smokers. Occupational exposures to toluene triggered an increase of post-shift levels (compared to pre-shift levels) of urinary cresol for non-smokers and workers who had less than 10 cigarettes during the work shift. For these groups, nonoccupational exposures before and during the work shift did not vary. For smokers who did not smoke during the work shift and for those who had more than ten cigarettes during the shift, the post-shift levels of both cresol and hippuric acid were reduced approximately 30% lower than pre-shift levels. This is due to increased exposures to tobacco smoke before the work shift. The relationships between phenol and (cresol ? hippuric acid) levels for non-smokers and smokers indicated that elevated coexposures due to smoking result in the reduction of all metabolites levels in urine. These findings demonstrated that exposures to tobacco smoke may stochastically interfere with occupational exposures when biological monitoring is used to assess occupational health risks. Factors influencing the magnitude of the interference were specimen collection time (in relation to the timing of occupational exposures and excretion rates of biomarkers), smoking intensity and timing before and during the work shift.

Assessment of Occupational Exposure to BTEX in a Petrochemical Plant via Urinary Biomarkers

“…The differences between cresol and hippuric acid (both are toluene metabolites) may be attributed to the different excretion times. Cresol is excreted 1 h after exposure, while the highest hippuric acid concentration is typically observed four to six hours after exposure [40,41]. O-Cresol showed low values compared to the BEI value of 0.3 mg g −1 of creatinine, which are in agreement with the low levels of airborne toluene.…”

“…The validity of these markers has been demonstrated for levels in the air exceeding 10 mg m −3 , which is the case in this study. However, to achieve better exposure assessments, the selection of appropriate urinary metabolites must consider other parameters such as metabolism mechanisms, time of sample collection, and other confounding factors [22,27,[40][41][42][43]. For example, smoking cigarette behavior has been confirmed to be a strong confounding factor for the urinary excretion of benzene metabolites at low levels and must therefore also be taken into consideration and evaluated in urinary biomonitoring [40,41].…”

Biological monitoring of petrochemical industry workers exposed to benzene, toluene, xylenes, methyl ethyl ketone, and phenol in Southern Iran

“…Our results showed a more significant correlation between benzene, xylene isomers, phenol, and MEK in breathing zone and their urinary metabolites in smokers than nonsmokers (P = 0.03, P = 0.041, P = 0.02, P = 0.039, and P = 0.042, respectively). Some other studies reported significant differences between smokers and nonsmokers exposed to benzene in ambient air (15,38). The distribution of pollutants from petrochemical factories into the ambient air mainly depends on the process activities.…”

“…In general, petrochemical industries including large-industrial are the high important of viewpoint occupational health and industrial safety. They are one of the sources of releasing VOCs in the atmosphere, due to production process, storage tanks, and wastewater of these industries (14)(15)(16). Biological monitoring of workers exposed to solvents are supplement environmental monitoring and could be used to evaluate the effects of workload, work habits, exposure to various routes, and in health risk assessment (17,18).…”