The personal exposure to benzene downwind and close to the oil slick during spills of light crude oil was relatively high, with concentration levels approaching the occupational exposure limits for several participants. For bulk spill scenarios like in this study, cleanup should not be initiated the first 30-60 min to allow for evaporation, while appropriate personal protective equipment should be used in continuous spills when working downwind and close to the oil slick.

Objectives: The main aim of this study was to assess the biological uptake of benzene and polycyclic aromatic hydrocarbons (PAHs) for subjects exposed to fresh crude oil released at sea. Methods: The study included 22 subjects participating in an «oil on water» field trial in the North Sea. Over two consecutive days there were six releases with two different types of fresh crude oils. Exposed subjects (N=17) were either located in small, open air boats downwind and close to the released oil (<50 m) or on the main deck of two large vessels further from the released oil (100-200 m). Subjects assumed to be unexposed (N=5) were located indoors on the command bridge of either vessel. Full-shift personal benzene exposure was monitored with passive thermal desorption tubes (ATD-tubes) packed with Tenax TA and subsequent gas-chromatographic analysis. Urine samples were collected before and after work-shift on both days and analyzed for urinary markers of benzene (S-Phenyl Mercapturic Acid, SPMA) and PAHs (1-Hydroksypyrene, 1-OH). Information about the use of personal protective equipment, smoking habits, location, work tasks and length of work-shift was recorded by a questionnaire. Results: Subjects located in the small boats downwind and close to the released oil were exposed to relatively high concentrations of benzene (arithmetic mean=0.2 ppm, range 0.002-1.5 ppm) compared to the occupational exposure limits (OELs) for 8 h (1 ppm) and 12 h (0.6 ppm). Although respirators were available to all exposed subjects, SPMA was detected in post-shift urine (0.5-3.3 µmol/mol) of five exposed subjects reporting not wearing respirators, all located in the small boats downwind and close to the released oil. For exposed subjects wearing respirators (N=12) the post-shift urinary SPMA was below the detection limit (0.8 µmol/mol) even when the benzene exposure exceeded the OELs. Urinary levels of PAH were within the reference range of what is considered as background levels (<0.4 µmol/mol). Conclusions: During the initial stages of a bulk oil spill at sea, when the evaporation of benzene is at its highest, it is important to use appropriate respirators to prevent biological uptake of benzene.

Benzene, toluene, ethylbenzene, xylenes, naphthalene and n-hexane evaporating from a thin oil film was measured for 30 min in a small-scale test system at 2 and 13 °C, and the impact of physicochemical properties on airborne benzene with time after bulk oil release was studied. Linear mixed-effects models for airborne benzene in three time periods; first 5, first 15 and last 15 min of sampling, indicated that benzene content in fresh oil, oil group (condensate/light crude oil) and pour point were significant determinants explaining 63-73% of the total variance in the outcome variables. Oils with a high pour point evaporated considerably slower than oils with a low pour point. The mean air concentration of total volatile organic compounds was significantly higher at 13 °C (735 ppm) compared to 2 °C (386 ppm) immediately after release of oil, but at both temperatures the concentration rapidly declined.

Background: In-situ burning (ISB) could be an effective cleanup method during spills. This study aims to study occupational exposure to pollutants emitted from offshore, large-scale ISB-experiments among personnel on vessels involved in ISB. Materials and methods: Six experimental ISBs after release of 4.2-6 m 3 crude or refined oils were performed. Air measurements on three vessels were taken of particulate matter (PM) of different size fractions, polycyclic aromatic hydrocarbons (PAH) and volatile organic compounds (VOC). Results: One vessel was located upwind (about 80-140 m) from the burning oil while two work boats were positioned 200-400 m downwind. One of the work boats moved back and forth transverse to the smoke plume while the other followed the edge of the smoke plume downwind. During the burn period (28-63 min) the range of mean concentrations of PM 2.5 particles in the closest work boat downwind from the burn (0.068-0.616 mg/m 3 ) was considerably higher than in the upwind vessel (0.0198-0.029 mg/m 3 ) and in the work boat moving downwind at the edge of the visible smoke (0.007-0.078 mg/m 3 ). The particles were mainly in the PM <1 fraction. In the work boat closest to the burn the mean concentration of particulate PAH and VOC was 0.046-0.070 ng/m 3 and < limit of detection -17.1 ppm, respectively. Conclusions: The mean PM 2.5 levels in the closest vessel varied between 4 and 41 times higher than the 24-hour Norwegian Air Quality Criteria for the general population, indicating that the particulate exposure may impose a health risk for personnel up to 400 m downwind from an ISB. Exposure to VOC and PAH among crew on board vessels both upwind and downwind from the burning was low during these conditions. However, it is recommended that crew on vessels close to and downwind of smoke plumes from oil fires should use half-masks with P3 filters.

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