Chapter Contents:

There has been a slow recognition that the importance of work for health goes beyond traditional occupational diseases (Schilling1989). Indeed, it is likely that work makes a greater contribution to diseases and ill-health not thought of as 'occupational’. Early research concentrated on the possible role of physical activity in the work place (Morris et al, 1953). Other work, more in the spirit of traditional occupational health, has specified a number of physical and chemical exposures (e.g. lead, carbon disulphide, carbon monoxide, nitroglycerin, nitroglycol (Kristensen1994)). More recently the workplace has been seen as an appropriate setting for health promotion activities: providing the opportunity to influence lifestyles such as smoking, diet and physical activity, and to conduct screening for disease risk (Breucker and Schroer 1996).

There is now evidence that psychosocial factors at work may play an important role in contributing to the social gradient in ill health. There have been a number of different approaches to measurement of work stress, and research more recently has tended to focus on a few explicit theoretical concepts. Among these, the models of job demand-control (Karasek1979, Karasek and Theorell 1990) and effort-reward imbalance (Siegrist et al, 1986, Siegrist 1996) have received special attention.

A number of different diseases have been related to psychosocial conditions in the workplace, most notably coronary heart disease (CHD), musculoskeletal disorders and mental illness. This paper touches on two types of question: the relation between conditions at work and disease; and the contribution this relationship may make to variations in disease in society. Because variations in coronary heart disease have been studied extensively, we start and end with that disease, but as the paper will endeavour to show a number of other disease end-points are important.

The Social Distribution of Coronary Heart Disease

It is worth reviewing the changing distribution of CHD internationally to put into context the possible contribution of work stress to the development of ill health and disease. There have been two major changes in the epidemiology of CHD over recent years: i) a changing social class distribution of the disease (Marmot1992) and (ii) a rise and fall in CHD in different countries (Uemura and Pisa1988). In many European countries, as in the USA, as CHD became a mass disease, it rose first in higher socio-economic groups and subsequently in lower, to the extent that the social distribution changed to the now familiar pattern of an inverse social gradient: higher rates as the social hierarchy is descended. More recently, the decline in CHD mortality both in the United Kingdom and the USA has been enjoyed to a greater extent by higher socio-economic groups leading to a widening of the social gap (Wing et al, 1992). Concerns that the predominance of CHD in higher socio-economic groups may relate to the stress of their occupations go back at least to Osler (1910) who wrote that work and worry were major causes of the disease. The fact that CHD is now more common in lower socio-economic groups does not, by itself, refute the potential importance of work 'stress'. Research has moved on from the simplistic notion that high responsibility or dealing with multiple tasks represents work stress.

There is now a widely validated body of knowledge on risk factors for CHD that relate to development of atherosclerosis, and a somewhat less secure body of knowledge relating to predisposition to thrombosis. The major risk factors are high levels of blood pressure and plasma total cholesterol and smoking. Although smoking, in particular, shows a strong social gradient (Marmot et al, 1991), these risk factors account for no more than one third of the social gradient in cardiovascular disease (Marmot et al, 1978, Marmot et al, 1984).

We are left then with two types of question. First, what accounts for the social and international variation in unhealthy behaviours such as atherogenic diet, smoking, and sedentary life style? Second, given that these factors appear to be inadequate explanations of social and international variations in cardiovascular mortality, what else could account for the observed differences? We have argued elsewhere that one must look for explanations in the nature of social and economic organisation of societies (Marmot 1994). One particular feature is the nature of working life, both because what happens in the work place may be important for health and because work and the operation of the labour market play a central role in the organisation of social and economic life, which in turn are important in the social determinants of health. The evidence that supports the importance of work for cardiovascular and other diseases is presented below.

The Changing Nature of Work

There are at least four important reasons for the centrality of work and occupation in advanced industrialized societies. First, having a job is a principal pre-requisite for continuous income opportunities. Level of income determines a wide range of life chances. Second, training for a job and achievement of occupational status are the most important goals of primary and secondary socialization. It is through education, job training, and status acquisition that personal growth and development are realized, that a core social identity outside the family is acquired, and that intentional, goal-directed activity in human life is shaped. Third, occupation defines a most important criterion of social stratification in advanced societies. Amount of esteem and social approval in interpersonal life largely depend on the type of job, professional training, and level of occupational achievement. Furthermore, type and quality of occupation, and especially the degree of self-direction at work, strongly influence personal attitudes and behavioral patterns in areas that are not directly related to work, such as leisure, family life, education, and political activity (Kohn and Schooler 1973). Finally, occupational settings produce the most pervasive and continuous demands during one´s lifetime, and they absorb the largest amount of active time in adult life. Exposure to adverse job conditions carries the risk of ill health by virtue of the amount of time spent and the quality of demands faced at the workplace. At the same time, occupational settings provide unique opportunities to experience reward, esteem, success, and satisfaction. To understand the impact of working life on health in general, it is important to realize the profound changes that have taken place in the nature of work in established market economies. Among these are the following:

• fewer jobs are defined by physical demands; more by psychological and emotional demands;
• fewer jobs are available in mass production, more in the service sector;
• more jobs are concerned with information processing due to computerization and automation.

These changes in the nature of work have gone along with changes in the nature of the labour market. There has been increasing participation of women in the labour market, an increase in short term and part-time working and, most importantly, an increase in job instability and structural unemployment. For instance, Hutton (1995) describes Britain as the 40-30-30 society: 40% of the male population of working age have secure jobs, 30% are not working, and 30% are in insecure jobs. The 30% not working may cause some surprise given that the official unemployment rate is around 8%. The 30% is made up of the official unemployed, those no longer seeking work, premature retirements, disabled and others. If 30% of the population are in insecure jobs, this must have effects on the rest of the working population who wonder if their job is next. This is a change. In Europe, until relatively recently there were national commitments to security of employment. Now, the rhetoric is labour market flexibility (Beatson1995). The other side of flexibility is job insecurity.

The 30% not working is not unique to Britain. In Finland, for example, the mean age of entry to the labour market is now 27 and mean age of exit is 53. When the Finnish social contract was nationally agreed the assumption was that working life would last 40 years. If it lasts 26 years, on average, this has a profound importance for the costs of the welfare state. It also changes attitudes to work if a job for life is no longer a realistic expectation for large sections of the labour market. Research on work and health has to take this job insecurity into account, especially so as loss of job was shown to be associated with elevated risk of mortality in independent prospective studies both in Britain and in Finland (Morris et al, 1994, Martikainen and Valkonen 1996).

This changing nature of work and the labour market has occurred at the same time as there have been substantial increases in income inequalities in many countries (Joseph Rowntree Foundation 1995). Wilkinson (1992) has shown that, internationally, life expectancy is related more closely to income distribution than to overall wealth as measured by gross national product. This has now been documented in two independent studies for the states of the USA (Kaplan et al, 1996, Kawachi and Kennedy 1997). If inequality, rather than absolute level of deprivation is an important driver of health differentials it may, as Wilkinson suggests in this book, be a reflection of the quality of the social environment. It may also suggest that discontent related to unfavorable social comparison (relative social deprivation) and associated stress reactions may have important health consequences.

The scientific challenge, then, consists in identifying those stress-eliciting conditions related to the nature of work, the structure of salaries (income distribution) and labour market constraints that may account for differences in morbidity and mortality that are reported within and between populations.

The Psychosocial Work Environment

Research on psychosocial work-related stress differs from traditional biomedical occupational health research by the fact that stressors cannot be identified by direct physical or chemical measurements. Rather, theoretical concepts are needed to analyse the nature of work in order to identify particular stressful job characteristics at a level of generalization that allows for their identification in a wide range of different occupations.

These theoretical concepts are operationalized using standardized methods of social and behavioral sciences (e.g. systematic observation, structured interviews, standardised questionnaires (so called paper and pencil tests)). Therefore, measuring stressful working conditions provides a theoretical and methodological challenge. As mentioned, in theoretical terms, those components of working life need to be identified that produce intense, recurrent, and long lasting stressful experience at least in a substantial proportion of those exposed. Moreover, researchers have to argue whether they restrict their formulations to particular job characteristics or whether they analyze stressful work experience in terms of an interaction of work characteristics and of coping characteristics of the working person.

At a methodological level, measures of work stress are expected to be reliable, sensitive to change, and valid. Two theoretical models: the demand-control model and effort-reward imbalance model fulfill these methodological criteria and identify stressful working conditions that are widely prevalent in advanced marked economies, such as changes in task profiles, work control, structure of salaries, and occupational stability. Over the past ten years these two models have been tested in a number of studies, and a substantial body of knowledge has been generated, strengthening the assumption that stressful experiences at work are associated with elevated risk of CHD and other diseases.

The Demand-Control Model

In the sixties, research on job conditions and CHD had explored working demands and working hours (Hinkle et al, 1968). In the seventies several research traditions found evidence for a favorable effect on mental health produced by skill development (Hackman and Lawler1971) and autonomy at work (Kohn and Schooler 1973, Gardell 1971). It was Karasek's original contribution to formulate a two-dimensional concept of work stress where a high level of psychological demands combined with a low level of decision latitude (low level of decision authority and low level of skill utilization) was predicted to increase the risk of stressful experience and subsequent physical illness (in particular CHD) (Karasek1979). In 1981, Karasek first found evidence of a predictive role of high demand-low control conditions in CHD, using data on a representative Swedish sample (Karasek et al, 1981). Since then, a large number of prospective and cross-sectional studies on associations of stressful work as defined by high demand and low control (job strain) with cardiovascular risk and disease have been conducted (for overviews see (Karasek and Theorell 1990, Schnall and Landsbergis 1994, Kristensen 1995, Theorell and Karasek 1996, Hemingway and Marmot 1998). A number of these studies have focused on methodological considerations and have used new outcome measures, the majority of which have revealed positive findings.

Karasek's original hypothesis that excessive psychological demands interact with lack of decision latitude in generating increased risk of cardiovascular disease was supplemented by a second hypothesis which concerns the learning of new patterns of behaviour and skills on the basis of psychosocial job experience. According to this, learning for adults accrues over a lifetime of work experience. It may contribute to the worker's possibility to exert control over his or her working situation and thus have an impact on broader conditions of adult life. According to this hypothesis, the active situation is associated with the development of a feeling of mastery which inhibits the perception of strain during periods of overload, for instance. This makes it likely that the active job situation may stimulate healthy functioning. Epidemiological studies in Sweden indicated that the active job situation is associated with high rates of participation in socially active leisure and political activities (see Karasek and Theorell 1990), and, on the contrary, the daily residual strain arising in the strain situation gives rise to accumulated feelings of frustration which may inhibit learning attempts. It is obvious that some of the 'classic' high strain jobs are found in mass industry, especially under conditions of piece work and machine paced assembly line work. Nevertheless, a number of strain jobs were also identified in the service sector. The concept therefore proves to be relevant in different employment sectors, and will remain important in the foreseeable future due to changing patterns of employment. For example, the rate of temporary employment is increasing in western Europe, particularly for those with low education. It is in these kinds of employment that lack of control will be a major problem. Even in those with a high education, the increasing demands for flexibility will create new decision latitude problems. The ever increasing demands for effectiveness from the workforce are raising the levels of psychological demands for all workers. This is particularly reflected in Swedish national welfare statistics.

The Effort-Reward Imbalance Model

At the beginning of this section we emphasized the growing importance of job insecurity in the current worldwide economy. 'Job control' in this perspective implies more than the original conceptualization which was directed towards characteristics of work tasks. A related concept, the model of effort-reward imbalance, focuses more explicitly on links between work tasks and labour market dynamics. The model maintains that the work role defines a crucial link between self-regulatory needs of a person (e.g. self-esteem, self-efficacy) and the social opportunity structure. In particular, conferment of occupational status is associated with recurrent options of contributing and performing, of being rewarded or esteemed, and of belonging to some significant group (work colleagues). Yet, these potentially beneficial effects are contingent on a basic pre-requisite of exchange in social life, that is, reciprocity. Effort at work is spent as part of a socially organized exchange process to which society at large contributes in terms of rewards. Rewards are distributed by three transmitter systems: money, esteem, and career opportunities including job security. The model of effort-reward imbalance claims that lack of reciprocity between costs and gains (i.e., high cost/low gain conditions) define a state of emotional distress which can lead to the arousal of the autonomic nervous system and associated strain reactions. For instance, having a demanding, but unstable job, achieving at a high level without being offered any promotion prospects, are examples of high cost-low gain conditions at work. In terms of current developments of the labour market in a global economy, the emphasis on occupational rewards including job security reflects the growing importance of fragmented job careers, of job instability, under-employment, redundancy and forced occupational mobility including their financial consequences (Siegrist et al, 1986, Siegrist 1996). The model of effort-reward imbalance applies to a wide range of occupational settings, most markedly to groups that suffer from a growing segmentation of the labour market, to groups exposed to structural unemployment and rapid socio-economic change. Effort-reward imbalance is frequent among service occupations and professions, in particular the ones dealing with person-based interactions.

It is important to note that the two models mentioned, the demand-control and the effort-reward imbalance model, differ in the following respects. First, while the demand-control model puts its explicit focus on situational characteristics of the work environment, an explicit distinction is made between situational and person characteristics in the effort-reward imbalance model. It assumes that a combination of both sources of information provides a more accurate estimate of experienced stress at work than a restriction to one of these two sources. Secondly, as was mentioned, components of the effort-reward imbalance model (salaries, career opportunities/job security) are linked to more distant macro-economic labour market conditions while the former model's major focus is on workplace characteristics. Finally, in stress-theoretical terms, the range of control over one's environmental situation at work is the core dimension in the demand-control model whereas, in the second model, threats to, or violation of legitimate rewards based on the assumption of reciprocity and fairness in social exchange represent the core dimension. Despite these differences there is promise in studying the combined effects of the two models in future research.

Conclusion

In this paper we have argued that two theoretical models hold particular promise in explaining at least part of the variation in CHD - a variation that may be attributed in part to work stress as defined by the demand-control and effort-reward imbalance models. High demand-low control conditions and high cost-low gain conditions at work are unequally distributed both between and within societies and may potentially provide a framework in which to understand the contribution of psychosocial factors at work to the development of disease.

The conceptual differences between the models have direct implications for the design of intervention measures to improve health; whereas the emphasis of the demand-control model is on change of the task structure (such as job enlargement, job enrichment and increasing the amount of support within the job etc.) the reduction of high cost-low gain conditions includes action at three levels, the individual level (e.g. reduction of excessive need for control), the interpersonal level (e.g. improvement of esteem reward), and the structural level (e.g. adequate compensation for stressful work conditions by improved pay and related incentives, opportunities for job training, learning new skills and increased job security).

Despite the central role of work in the above models, an exclusive focus on working life runs the risk of underestimating the true costs on health produced by other adverse stressful circumstances that can occur outside of work. This becomes dramatically clear if we consider the evidence on the health burden of long-term unemployment (Martikainen and Valkonen 1996). The characteristics of family life and leisure activities are also of crucial importance in reducing the stresses and strains of working life. Conversely, stressful events in an individual’s personal life, such as marital problems and lack of social support can also exacerbate the burden of work-related stress and may increase a person's disposition towards developing disease. The study of the work-family interface points to the need to extend the framework of reference in stress research by taking into account the broader social determinants of health.

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