Occupational exposure to carcinogenic agents on the decks on six Norwegian crude oil tankers was examined in five harbors. The purpose of the study was to evaluate the need for improving the working environment on deck on these tankers. Technical arrangements and the work itself on the deck were observed during loading or unloading. Occupational monitoring was performed by active sampling of benzene, polyaromatic hydrocarbons, and some aldehydes. The crew answered a questionnaire concerning their work, use of protective equipment, and occurrence of acute symptoms. The levels of air-borne carcinogenic agents were low, probably due to closed loading systems on all tankers. However, the seamen reported discomfort during the work that may be related to other chemical agents in the cargo. The seamen were frequently painting with lead chromate paint without using personal protective equipment. This type of chemical exposure should be evaluated.
Drilling operations can require the usage of oil base drilling fluids (OBM). These fluids are formulated as an emulsion consisting of water emulsified into a continuous oil phase. During the last decade the North Sea drilling industry has moved from using diesel oil to low toxic base oils in OBM. Further development of low toxic base oils has continued on the Norwegian Sector of the North Sea, and resulted in the use of non-aromatic base oils. The current paper describes the results from a field test where the introduction of non-aromatic base oils reduced the hydrocarbon content by more than 50% in head space level in the shale shaker area compared to the use of low toxic base oils. In this test two wells were drilled where the hydrocarbon vapour and mist were collected at the same locations in the shaker area. The first well was drilled with a more traditional low toxic mineral oil based drilling fluid. The second well was drilled in a comparable formation with a drilling fluid based on the non-aromatic base oil. The paper also describes how skin irritation is reduced when using the non-aromatic base oils compared to the use of previous base oils and synthetic base oils. The reduction in skin irritation and hydrocarbon content at head space level has significantly improved the occupational hygiene for personnel exposed to drilling fluids offshore. The paper also discusses biodegradability and toxicity of different base oils. Ecotoxicological test results indicate that use of the non-aromatic base oils may result in less environmental impact compared to use of other mineral oils or synthetic oils if an accidental discharge occurs. Finally, the paper discusses dermal irritation effects from the different drilling fluids. It is shown that use of the non-aromatic base oil reduces the skin irritation index compared to use of other oil or synthetic base oils. Introduction During a period in the fall of 1997 a well was drilled with used low toxic mineral oil based drilling fluid (LTOBM) on a field on the Norwegian sector of the North Sea. On a comparative well drilled in the spring 1998, the OBM was based on non-aromatic base oils (NAOBM). The hydrocarbon content in the air at head space level was measured at the same locations at those drilling operations. Both of the OBMs were used; thus leaving the OBMs slightly polluted by reservoir oils. The pollution by reservoir oils is anticipated to have only limited effect on the overall occupational hygiene and environmental properties of the OBMs. Before proceeding it is important to define the term non-aromatic base oil. Non-aromatic is meant to describe an oil without any measurable content of poly-aromatic hydrocarbons. Other types of hydrocarbons containing cyclic compounds are not described by the term aromatics in the present context. Accidential spills of OBM can occure. Therefore it is important to outline how big an impact the OBM will have on the marine environment compared to synthetic based fluids like Ester based drilling fluids or linear alphaolefine based drilling fluids since cuttings drilled out with the latter drilling fluids can be permitted. Inhalation of oil mist and oil vapour may lead to irritation of the mucous membrane and the respiratory organs. Aspiration of oil may lead to chemical pneumonia. The most commonly reported health effects reported due to inhalation of oil mist or vapour are acute effects, such as headache and nausea. Long term health effects such as cancer or reproductive effects has not yet been proven. However, precautions are taken within the industry to avoid these problems by selecting acceptable base oils for oil based drilling fluids.
Summary Drilling operations can require the use of oil-based drilling fluids (OBM). These fluids are formulated as an emulsion consisting of water emulsified into a continuous oil phase. During the past decade, the North Sea drilling industry has moved from using diesel oil to low-toxic base oils in OBM. Further development of low-toxic base oils has continued on the Norwegian sector of the North Sea and has resulted in the use of nonaromatic base oils. This paper describes the results from a field test in which the introduction of nonaromatic base oils reduced the hydrocarbon content by more than 50% in head space level in the shale shaker area, compared to the use of low-toxic base oils. In this test, two wells were drilled in which the hydrocarbon vapor and mist were collected at the same locations in the shaker area. The first well was drilled with a more traditional low-toxic, mineral-oil-based drilling fluid. The second well was drilled in a comparable formation with a drilling fluid based on the nonaromatic base oil. The paper also describes how skin irritation is reduced when using the nonaromatic base oils, compared to the use of previous base oils and synthetic base oils. The paper discusses biodegradability and toxicity of different base oils. Ecotoxicological test results indicate that use of the nonaromatic base oils may result in less environmental impact, compared to the use of other mineral oils or the synthetic oils used in Norway, if an accidental discharge occurs. Finally, the paper discusses dermal irritation effects from the different drilling fluids. It is shown that use of the nonaromatic base oil reduces the skin irritation index compared to use of other oil or synthetic base oils. Introduction During a period in the fall of 1997, a well was drilled with low-toxic, mineral-oil-based drilling fluid (LTOBM) on a field in the Norwegian sector of the North Sea. On a comparative well drilled in the spring of 1998, the OBM was based on nonaromatic base oils (NAOBM). The hydrocarbon content in the air at head space level was measured at the same locations at those drilling operations. Both of the OBM's were used, thus leaving the OBM's slightly polluted by reservoir oils. The pollution by reservoir oils is anticipated to have only a limited effect on the overall occupational hygiene and environmental properties of the OBM's. Before proceeding, it is important to define the term "nonaromatic base oil." Nonaromatic is meant to describe an oil without any measurable content of polyaromatic hydrocarbons. Other types of hydrocarbons containing cyclic compounds are not described by the term "aromatics" in the present context. The aromatic content measured by UV analysis indicates that the low-toxic base oil had an aromatic content of less than 5 wt%, while the aromatic content of the nonaromatic base oil was less than 0.01 wt%. A typical aromatic content value was estimated to be 0.003 wt%. Accidental spills of OBM can occur. Therefore, it is important to outline how great an impact the OBM will have on the marine environment, compared to synthetic-based fluids such as ester-based drilling fluids or linear alphaolephine (LAO)-based drilling fluids, because cuttings drilled out with the latter drilling fluids can be permitted in some cases. In the following, only synthetic drilling fluids used in Norway will be discussed. Inhalation of oil mist and oil vapor may lead to irritation of the mucous membrane and the respiratory organs. Aspiration of oil may lead to chemical pneumonia. The most commonly reported health effects reported due to inhalation of oil mist or vapor are acute effects, such as headache and nausea. Long-term health effects such as cancer or reproductive effects have not yet been proven. However, precautions are taken within the industry to avoid these problems by selecting acceptable base oils for oil-based drilling fluids. Field Measurements To investigate the effect of base-oil properties on occupational hygiene, a field evaluation was conducted. The field evaluation consisted of four series of measurements for each OBM. Active sampling techniques using filter for oil mist and absorbents for oil vapor were performed with a PVC filter and a charcoal absorbent in series for both the stationary and the personal measurements. The PVC filters were extracted with Freon 113 and analyzed with infrared spectroscopy (IR). The charcoal absorbents are desorbed with carbon disulphide and analyzed by gas chromatography-flame ionization detector (GS-FID). Pumps are set for an air flow of 1.4 l/min, and air-flow control is performed at the start and end of each series of measurements. Each series had a duration of 1 hours; this period was chosen to optimize data quality because the time is long enough to collect data, and the time is also short enough to prevent the evaporation of the mist in the probes. The hydrocarbon threshold values for the combined sampling and analysis are 0.1 mg/m3 for mist measurements and 0.03 mg/m3 for the vapor measurements. The overall uncertainty is 10% of reported value for both the mist and vapor measurements. The hydrocarbon content and oil mist were collected at four measurement points. The drilling rig was equipped with four shakers. The first measurement point, Point A, was positioned at head space level between two of the shakers on the walkway in front of the shakers. The second point, Point B, was located at head space level above the flow channel for drilling-fluid sample collection, between two of the shakers. Point C was located at the work table for repair of shaker screens. The last measurement probe, labeled Point D, was carried by a person working in the drill floor area. The positions of the three fixed measurement collection points are shown schematically in Fig. 1 . All the measurement points are located in positions relevant to the daily exposure of personnel working in the drilling-fluid area or in the vicinity of that area. None of the measurement points was located inside special protection gears mounted to prevent vapor or mist from escaping to other parts of the rig. Thus, the measurement points span the typical working area for drilling-fluid personnel.
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