It is well established that benzene is carcinogenic to humans causing e.g. acute myeloid leukaemia/acute nonlymphocytic leukaemia (Baan et al. 2009). Recent reports indicate that haematoxic and carcinogenic effects may occur at substantially lower exposure concentrations than previously thought (Khalade et al. 2010, Rushton et al. 2014).

The European Chemicals Agency (ECHA), Committee for Risk Assessment (RAC), therefore proposed a lowering of the occupational exposure limit (OEL) for benzene from 1 ppm to 0.05 ppm (time weighted average (TWA) for 8 hours exposure) (ECHA, 2018). This proposed reduction to one twentieth of the current OEL required a reassessment of the measurement strategies as well as risk management practices in the Norwegian oil and gas industry.

As a result of this work, this study was initiated by STAMI in January 2019 in collaboration with AkerBP ASA, ConocoPhillips Skandinavia AS, Equinor Energy AS, Lundin Norway AS, Neptune Energy Norge AS, A/S Norske Shell, Vår Energi AS and Wintershall Dea Norge AS.


This study explores whether urinary benzene (U-BEN) and urinary S-phenyl mercapturic acid (U-SPMA) as biological markers of occupational exposure to low (< 0.2 ppm) and intermittent concentrations of benzene are good alternatives to personal air sampling of benzene in the offshore environment and at onshore facilities. The following aims were established:

  • Assess among approximately 400 workers in the oil and gas industry and fuel terminals changes in concentrations of U-BEN and the specific metabolite of benzene U-SPMA before, during and after the end of a 12 hour work shift.
  • Examinate the appropriate timing of urine sample collection under these working conditions with respect to concentrations of U-BEN and U-SPMA by collecting five urine samples per worker.
  • Examinate the suitability of U-BEN and U-SPMA as biological markers for full-shift low and intermittent exposures to benzene.
  • Assess among approximately 400 workers in the oil and gas industry and fuel terminals time-weighted average concentrations of benzene in workroom air samples collected by paired active and passive personal air sampling.
  • Compare the TWA concentrations of benzene determined in air with the concentrations of U-BEN and U-SPMA determined in urine by carefully considering other non-occupational sources of benzene exposure, including cigarette smoking (also second hand smoke), road vehicle emissions and fuels and the use of personal protection equipment.
  • Perform a field validation of the personal active air sampling method.
  • Perform a laboratory test of the active air sampling method to explore the limitations of this sampling method at very humid sampling conditions.


One report to our industrial partners and four scientific papers are in progress. Due to the Covid pandemic, data collection onshore and offshore was postponed, but the work is now progressing in accordance with revised time schedules.

Project Group

Prosjct Leader: Raymond Olsen

Project group: Dag Ellingsen, Hanne Line Daae, Pål Graff, Kristin Helmersmo, Håkan Wallin, Erika Zardin.