Exposure to carcinogens for defined job categories in Norway's offshore petroleum industry, 1970 to 2005

Our plain-English summary of Exposure to carcinogens for defined job categories in Norway's offshore petroleum industry, 1970 to 2005, by K. Steinsvåg, M. Bråtveit, B.E. Moen (Occupational and Environmental Medicine, 2007).

The study

• Authors: K. Steinsvåg, M. Bråtveit, B.E. Moen
• Journal: Occupational and Environmental Medicine
• Published: 2007;64(4):250-8
• Cited by: 27 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Objectives: To identify and describe the exposure to selected known and suspected carcinogenic agents, mixtures and exposure circumstances for defined job categories in Norway's offshore petroleum industry from 1970 to 2005, in order to provide exposure information for a planned cohort study on cancer.

Methods: Background information on possible exposure was obtained through company visits, including interviewing key personnel (n = 83) and collecting monitoring reports (n = 118) and other relevant documents (n = 329). On the basis of a previous questionnaire administered to present and former offshore employees in 1998, 27 job categories were defined.

Results: This study indicated possible exposure to 18 known and suspected carcinogenic agents, mixtures or exposure circumstances. Monitoring reports were obtained on seven agents (benzene, mineral oil mist and vapour, respirable and total dust, asbestos fibres, refractory ceramic fibres, formaldehyde and tetrachloroethylene). The mean exposure level of 367 personal samples of benzene was 0.037 ppm (range: less than the limit of detection to 2.6 ppm). Asbestos fibres were detected (0.03 fibres/cm3) when asbestos-containing brake bands were used in drilling draw work in 1988. Personal samples of formaldehyde in the process area ranged from 0.06 to 0.29 mg/m3. Descriptions of products containing known and suspected carcinogens, exposure sources and processes were extracted from the collected documentation and the interviews of key personnel.

Conclusions: This study described exposure to 18 known and suspected carcinogenic agents, mixtures and exposure circumstances for 27 job categories in Norway's offshore petroleum industry. For a planned cohort study on cancer, quantitative estimates of exposure to benzene, and mineral oil mist and vapour might be developed. For the other agents, information in the present study can be used for further assessment of exposure, for instance, by expert judgement. More systematic exposure surveillance is needed in this industry. For future studies, new monitoring programmes need to be implemented.

In plain English

This study described possible exposure to known and suspected cancer-causing agents in Norway's offshore petroleum industry from 1970 to 2005. It was background for a planned cancer study. The authors visited companies and authorities, interviewed 83 key personnel, and collected 118 sampling reports and other documents. They grouped job titles into 27 job categories and identified possible exposure to 18 such agents, mixtures or exposure circumstances. Measurement reports were found for only seven agents. For benzene, 367 personal samples had a mean of 0.037 ppm, ranging up to 2.6 ppm. Asbestos was used as a drilling mud additive until 1980 and in drilling brake bands on some installations until 1991. On installations built before 1985 it was also used as fire protection, in gaskets and as insulation. Stationary air samples from the drilling floor of one installation in 1988 found 0.03 fibres per cubic centimetre above the brake drum. The authors concluded that quantitative exposure estimates might be developed for benzene and for mineral oil mist and vapour. They also concluded that more systematic exposure surveillance is needed.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Descriptive exposure assessment based on interviews with key personnel and collected documents and monitoring reports; no cancer outcomes were studied
• Who was studied: Job categories in Norway's offshore petroleum industry, 1970 to 2005. The researchers grouped 294 job titles from a 1998 Cancer Registry of Norway questionnaire cohort into 27 job categories in five work sections. Information came from 83 interviewees at 20 companies and from authorities, collected between December 2002 and November 2005.
• Exposure: 18 known and suspected carcinogens, including asbestos. Asbestos was used as a drilling mud additive (until prohibited in 1980), in brake bands in drilling draw works (on some installations until 1991), and as fire protection, gaskets and insulation on installations built before 1985. The fibre type is not specified.
• Main results:
  • Monitoring reports were found for only seven agents: benzene, mineral oil mist and vapour, respirable and total dust, asbestos fibres, refractory ceramic fibres, formaldehyde and tetrachloroethylene.
  • Benzene: 367 personal samples had a mean of 0.037 ppm (range from below the limit of detection to 2.6 ppm). The deck category had the highest geometric mean, 0.010 ppm.
  • Asbestos: stationary samples on the drilling floor of one installation in 1988, while asbestos-containing brake bands were in use, detected 0.03 fibres per cubic centimetre above the brake drum and 0.02 in other brake dust samples. The number of measurements is unknown. The brake lining contained 41% asbestos.
  • Based on interviews and documents, the authors judged that later removal of asbestos gaskets and insulation probably caused asbestos exposure, especially for insulators, and also for the process category and the maintenance, inspection, deck and construction categories.
  • Formaldehyde: personal samples taken during biocide work ranged from 0.06 to 0.29 mg/m3.
• The authors' conclusion: The authors concluded that quantitative exposure estimates might be developed for benzene and for mineral oil mist and vapour in the planned cohort study. For the other agents, including asbestos, the information could support further assessment such as expert judgement. They also concluded that more systematic exposure surveillance and new monitoring programmes are needed.
• Limitations the authors state:
  • Apart from the benzene and mineral oil data, the sampling data were fragmentary and indicate exposure levels only for specific processes.
  • Informants were often accompanied by a company leadership representative, which might have led them to hold back information. Companies also chose who was interviewed.
  • The authors did not expect to have obtained a complete set of existing documentation, partly because of complicated or incompatible archives.
  • Walk-through surveys of workplaces were not possible.
  • Only 55 of the 367 benzene samples described the tasks performed during sampling.

Topics

Medical terms in this study, explained in our Lexicon: Carcinogenic, Cohort Study, Personal Breathing Zone Sample.

Related studies

• Update of mortality and cancer incidence in the Australian petroleum industry cohort — R.T. Gun, N. Pratt, et al. (2006)
• Update of a prospective study of mortality and cancer incidence in the Australian petroleum industry — R.T. Gun, N.L. Pratt, et al. (2004)
• Asbestos-related cancers in refinery workers in the Australian petroleum industry — R. Gun, N.L. Pratt, et al. (2006)
• Mortality and cancer morbidity in a cohort of Canadian petroleum workers — R.J. Lewis, A.R. Schnatter, et al. (2003)
• An updated study of mortality among workers at a petroleum manufacturing plant — Y. Honda, E. Delzell, et al. (1995)
• An updated mortality study of workers at a petroleum refinery in Beaumont, Texas — G.K. Raabe, K.W. Collingwood, et al. (1998)

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