Occupational Medicine

-The essence of occupational health

Where do you come from, and what kind of occupational or environmental factors may affect your health? This Ramazzini's question to the patient reveals the basic idea of occupational medicine (Ramazzini, 1713). The answer to this question should be read as essential information from every patient's medical record.

In the clinical context, occupational medicine is often seen as a branch of medicine which examines occupational diseases, but, in the scientific context, occupational medicine investigates a wide variety of associations between work and health (Figure). Factors at work may promote health, but they can also aggravate the symptoms of diseases or cause new diseases (work-induced diseases). All illnesses can also influence the worker's work ability, and can therefore be considered as work-related. According to this view, occupational medicine provides a medical basis for all aspects of occupational health practice.

Research on occupational medicine has traditionally produced knowledge of the etiology of occupational diseases. The definition of a compensated occupational disease is based on national legislation and compensation practices, and varies from one country to another. In Finland, as in many other countries, a disease attributable to work is considered an occupational disease if it is likely to be caused, and is mainly caused by a physical, chemical or biological factor at work.

A considerably larger disease group consists of those common diseases whose symptoms are aggravated or worsened by various factors at work. The task of occupational medicine is to find evidence of an etiologic attributable fraction of work having an impact on different diseases (the fraction of incidence of a disease that would be eliminated if the exposure in question would not exist), even though the causal relationship between the working conditions and the disease cannot be proven at the individual level.

Occupational asthma is a good example of a work-induced disease. In Finland about 5% of all asthma cases are considered to be occupational diseases. However, a high-class register study (Karjalainen et al. 2001) showed that the etiologic attributable fraction of asthma was 29% in working-aged men and 17% in women. Irritants at work were shown to worsen the symptoms of 21% of the asthmatics at least weekly, although the onset of their asthma was not caused by factors at work (Saarinen et al. 2003).

Musculoskeletal disorders is another example of work-induced diseases. E.g., the lifting of heavy loads, repetitive work movements and awkward positions are known to aggravate the symptoms, although the causal relationship can seldom be shown at the individual level.

Practical occupational medicine focuses on promoting the health of people at work, and aims at ensuring their safe functioning, taking into consideration any health problems they may have. It also contributes to the organizational effectiveness of enterprises by providing medical advice to the management (Nicholson 2001). The preventive measures within the scope of occupational medicine can be classified as primary, secondary and tertiary prevention of work-related diseases.

Primary prevention aims to prevent the onset of disease by reducing or eliminating exposure to a hazardous agents in the workplace. In order to carry out primary prevention successfully, the health professionals must be familiar with the working conditions. In work place surveys, occupational health professionals assess the workers' exposure to physical, chemical, biological and psychosocial factors at work, and the health risks related to these exposures. In the risk assessment they utilize their knowledge of occupational epidemiology, toxicology, industrial hygiene, ergonomics and psychology. After the risk assessment, they plan relevant preventive measures in cooperation with the representatives of the work place.

Secondary prevention aims at detecting diseases when they are still pre-symptomatic or at an early stage, by utilizing health surveillance. Surveillance programmes for employees are planned according to evidence gained from occupational medicine. There is indication that, for example, occupational asthma can be diagnosed earlier, and the outcome is better as a result of health surveillance (Tarlo et al. 2002). Periodic health examinations of the workers also help in tertiary prevention of occupational diseases, which aims at preventing the symptoms from worsening by early recognition and transferring the affected workers from the exposure. More research is needed in order to assess the significance of the measures applied in tertiary prevention, also from the perspective of health economy.

If the disease does not fulfil the criteria of an occupational disease, it does not mean that nothing should be done. Today's real challenge for work life and the health care system is to initiate activities to find out and prevent not only occupational diseases, but also work-related symptoms as early as possible (Mcdonald 1997). It has even been postulated that occupational medicine is now at a turning point. Its emphasis is being shifted to occupational illness, i.e. work-related symptoms indicating an absence of well-being. This is not a simple function of excessive exposure to noxious agents, e.g. indoor air problems (Coggon 2005). The health surveillance programmes within the occupational health care system offer a good opportunity to detect the first signs of health problems related to work. The challenge remains to find interventions to treat these problems effectively.

Any common disease may affect a worker's quality of life and decrease his/her work ability. This is a growing problem throughout Europe, where the work force is ageing rapidly. Occupational health physicians treat illnesses, assess the work ability of employees, and participate in their rehabilitation. The health problems affecting work ability are managed as a cooperative effort by the occupational health service and the company's management. The knowledge about the connection between work and disease obtained through research in occupational medicine forms the foundation of these activities.

Cooperation is needed between occupational physicians and clinicians of different specialties in the identification and management of occupational diseases at the individual level. Many clinical specialities share some aspects of occupational medicine, for example, in the case of occupational lung diseases, skin diseases and otorhinolaryngeal diseases. For most occupational diseases it holds that the sooner the occupational diseases are diagnosed, the better will be the outcome. Therefore, the diagnostic processes of occupational medicine should be integrated effectively into the national health care system. If occupational health physicians do not treat patients, it is essential that general practitioners and clinical specialists be encouraged and motivated to diagnose diseases in cooperation with the local centres of occupational medicine.

Occupational health services collect health information from a variety of sources, such as health examinations, questionnaires for specific purposes, the reasons for sick leaves, early retirement, or visits to the doctor, when curative care is included in the company's occupational health service arrangement. The employees' health information should be applied to corrective and preventive measures at the work place, at both group and individual level.

Occupational health can be defined according to the view of Koren (2005). It is the capability of a person to function at an optimum level of productivity in a work situation while enjoying good health and longevity. Occupational medicine is a field of preventive medicine related to the problems and practice used in protecting health, preventing disease or injury and promoting the working capacity of workers. Occupational medicine is the very essence of all occupational health services. Occupational health care systems may vary in different countries, especially in respect to the extent of multidisciplinarity, the utilization of other specialities, and the role of curative activities (Rantanen 2005). The provision of occupational health services which will give optimal support to a person's functional capability, is initially based on the values and resources of society.