The objective of the study was to examine whether male tobacco smokers had a more unhealthy ... Key words: oil workers, smoking, diet, North Sea, platforms.
Tobacco smoking, an independent determinant for unhealthy diet? A cross-sectional study of Norwegian workers on platforms in the North Sea ARNE OSHAUG, CHRISTINE HELLE BJ0NNES, KARl H. BUGGE, KERST1N U. TRYGG •
Key words: oil workers, smoking, diet, North Sea, platforms
L revious American, British and Norwegian studies have demonstrated the harmful effect of smoking.1"5 The pattern is similar in different countries, 6 " 12 and among men and women of various ages. 7 ' 13 ' 1 * However, in some studies, smoking tends to be associated with a number of seemingly unrelated disorders.5 This suggests that smoking acts both as a causal factor and as a marker of an unhealthy lifestyle. 15 " 25 This clustering of lifestyle factors is more easily studied in closed communities, with a constant supply of foods and nutrients. Platforms producing oil in the Norwegian sector of the North Sea can be considered as closed communities. They provide a setting where several factors, which otherwise vary substantially, are stable or vary little (i.e. sleeping quarters, living rooms, health care, restaurants, food availability, meal patterns). On these platforms a wide variety of foods are freely available, including cold dishes on buffets, several hot dishes, vegetables, green salads, fruits, desserts, fresh bread and rolls, etc. and meals are served at regular hours. What is offered to the workers is not influenced by each individual's education, social situation, economy and other socioeconomic factors, cultural backgrounds and values. People live on die platform for 2 weeks, most of them on a shift-work schedule, alternating with 3—4 weeks off. The dietary intake on the platform is there-
* A. Ojhaug', C H . BJennes". ICH. Bugs*'. *-U1 Nordic School of Nutrition. University of Oslo. Norway 2 Section for Dietary Research, Institute for Nutrition Research, University of Osto, Norway Correspondence: Ame Oshaug. Associate Professor, Nordic School of Nutrition. P.O. Box 1046 BUndcrn. 0316 Oslo, Norway, tel. +47 22 851379. fax +47 22 851341
fore totally dependent on each individual's choice and factors which can influence this choice at the work site. The hypothesis of this study is that tobacco smokers living on platforms in the North Sea have a more unhealthy diet than non-smokers even though the food availability is the same. PARTICIPANTS AND METHODS Participants
The study population in this cross-sectional study was recruited from 2 permanent production platforms in the Norwegian sector of the North Sea. All participants (n-=-310) were healthy men (according to a health certificate which must be renewed every second year), with a mean age of 37 years in the non-smoking group and 39 in the smoking group. Only Norwegian male workers on the day shift were included in this study and only 10% of the total population were women. The average total population (including women) on the bigger platform was 309 persons per day of which 56 worked on the night shift or were of foreign nationality, leaving 253 persons per day as possible participants. From this platform 252 persons (including women) participated in the survey. On the smaller platform the average population was 191 persons per day, of whom 52 worked the night shift or were not Norwegian citizens, leaving 139 persons as potential participants in the survey. On this platform, 126 persons were interviewed. Because the first day of work includes travel and thus may influence the diet, only those who had been on the platform at least 2 days prior to the interview were included in the analysis. Thus, the sample size in this study is 310 males.
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The objective of the study was to examine whether male tobacco smokers had a more unhealthy diet than non-smokers. Data on smoking and other variables were collected by questionnaire interviews and food intake by one 24 h recall. The setting was 2 oil platforms. The participants were 310 healthy men working on 2 platforms in the Norwegian sector of the North Sea. The mean ages were 37 and 39 years for non-smokers and smokers. The prevalence of smoking was 50.3%. Smoking decreased with increasing level of education, but increased with degree of urbanization. Smokers consumed less vegetables, fruit and fish, but more meat, soft drinks containing sugar and more coffee than non-smokers. Smokers had a higher intake of fat and a lower intake of carbohydrate, vitamins A, D and C and dietary fibre. Smoking was an independent predictor for increasing the consumption of coffee and high intake of energy, energy from fat and cholesterol and a decreasing consumption of vegetables, fruit, energy from carbohydrates, dietary fibre and vitamins A and C rt is concluded that smokers had a more unhealthy diet than non-smokers.
Smo/ong and diet m the North Sea
Data collection
Statistical analysis
The information on the diet was coded by food item and amount and analysed by a nutrient database and computer program developed by the Section for Dietary Research, University of Oslo. 26 Consumption of foods and the intake of nutrients were also adjusted for energy (per 10 MJ). As the distribution of consumption of food items is often skewed, with frequent 0 values, the analysis of differences and relationships used non-parametric statistical methods. For the identification of relationships between smoking and the 6 underlying non-dietary factors age, household category, length of education, residential area, occupation and months worked offshore (categorized as in table I), Spearman correlations coefficients were calculated. Multiple linear and logistic regression analyses were used to control for possible confounding variables. Age and months worked offshore were used as continuous variables, and smoking was coded in 3 categories: smoking, ex-smoking and never-smoking. Throughout the analysis the Statistical Package for the Social Sciences was used.27 RESULTS The prevalence of smokers in the sample was 50.3%, as shown in table 1. The median number of cigarettes among smokers was 14 cigarettes per day. Smoking was associated with length of education (rf » -0.18, p-0.002), occupation (r5 = -0.13, p°0.002) and residential area (ri = 0.14, p=0.02), with less smoking among those with a higher education and more smoking among those living in urban areas. There was a tendency for less smoking among managers and office workers (- 40% smoking), than among workers on drill-floor and maintenance workers (~ 60%), however, this was not statistically significant.
In logistic regression models education, residential area and age were independent predictors of smoking. Table 2 shows the mean intake of selected foods in the different categories. Ex-smokers differed little from nonsmokers. Ex-smokers consumed less vegetables and yoghurt and more whole-fat milk and coffee than neversmokers (consumed and consumption are used here as the mean intake). None of the other differences were statistically significant. Smokers consumed inter alia less vegetables and fish, but more meat, soft dnnks containing sugar and coffee than never-smokers. These variations may be due to differences in energy intake. Intakes of the foods were therefore adjusted for energy intake (grammes per 10 MJ). After adjusting for energy, smokers consumed significantly less vegetables, fruit and fish, but more soft drinks containing sugar and coffee than never-smokers (table 3). The mean consumption of soft drinks among smokers was 103 g per person per day and 59 g among never-smokers, while coffee consumption was 828 g/day and 451 g/day respectively (table 3). In the multiple linear regression model smoking was an independent predictor of coffee consumption (p
