The IOH: broadening the focus of OH research

Professor Jouni Jaakkola of the University of Birmingham's Institute of Occupational Health explains to John Manos how he hopes his background in occupational and environmental health epidemiology will influence the direction of the institute's future development.

The Institute of Occupational Health's (IOH's) recent annual workshop was the first held under the professorship of Jouni Jaakkola, whose career in occupational and environmental health research has included positions in Finland, Sweden, the USA and Russia. His work has focused on respiratory disease, particularly on the effects of indoor air pollution and passive smoking, and on occupational asthma, which was a principal theme of the Institute's recent annual workshop. In this first part of our report on the workshop, we present Jaakkola's views on the likely future activities of the Institute and some of the broader challenges facing occupational health in the UK.

Recent developments in the state of knowledge about occupational asthma illustrate why academic institutions like the University of Birmingham will tend to broaden their focus from pure occupational health activity, based on clinical medicine, to encompass more environmental health research, including more population studies, risk assessment and prevention, Jaakkola suggests.

The unique nature of sensitiser-induced occupational asthma (SIOA)

"Occupational asthma is a very special occupational illness because clinical evidence has provided such strong tools for showing causation in individuals. In contrast to, say, cancer, clinical science has been successful in demonstrating causal links with high certainty simply by studying individuals and perhaps taking workplace exposure measurements. In the case of traditional, sensitiser-induced asthma it is possible to diagnose asthma using strict criteria, often identifying biomarkers of sensitisation, and then identifying [and controlling] the presence of the sensitisers in the workplace. I cannot think of another occupational disease where the tools of clinical medicine are so strong," Jaakkola says.

"[However,] as asthma research has developed - identifying not only traditional sensitising agents but also describing asthma caused by exposure to irritants - it becomes less easy to show the causal link; occupational health increasingly has to move from the certainty of demonstrating the link in individual patients to assessment of risk of stochastic effects, as with cancer, which is conceptually different.

"As irritant-induced asthma has become a more accepted occupational disease category, the field which has been driven mainly by clinical medicine in the past has to be more concerned with epidemiological data. This is more advanced in Finland where there is good epidemiological data linking high risk of asthma in certain types of work with certain exposures, although it is not possible clearly to show that those exposures caused the effect in particular individuals," explains Jaakkola.

Two such examples of more recently characterised irritants with potential to cause asthma are moulds and environmental tobacco smoke (ETS).

Moulds are not sensitisers in the traditional sense (although work is being done on identifying biomarkers of exposure), but the results of Finnish case-control studies presented to the workshop by Dr Maritta Jaakkola, consultant respiratory physician at the IOH, showed that bakers (also affected by flour and spices) and forestry workers are the workers most at risk of mould-induced asthma (among males). Maritta Jaakkola also reported Finnish evidence of a dose/response relationship between the incidence of irritant-induced asthma in waiters and their exposure to environmental tobacco smoke; and a greatly increased risk among waitresses for which ETS was the most likely cause.

"More and more such cases of asthma are arising where it is necessary to infer that the cause is exposure to irritants, rather than sensitisers, and where evidence to demonstrate a causal link will never exist because of the nature of this form of asthma," Professor Jaakkola says. "It is often a feature of both occupational and environmental health that you have both a public health perspective and also a clinical medicine perspective on particular issues. Asthma illustrates the importance of this dual approach very nicely: the clear achievements of clinical medicine and the importance of population studies; both are needed if important information is not to be missed," he explains.

Case management of occupational asthma sufferers

Dr Alastair Robertson, of University Hospitals Birmingham Trust, presented to the workshop his personal occupational asthma case management experience, referring also to reviews from the literature. He described how the "hierarchy of preferred control options" was applied in practice where sensitisation has been identified or suspected (ie removal of the sensitising agent; enclosure of the source or use of local exhaust ventilation; and, as a last resort, relocation of the most sensitised individuals and/or restriction of controlled exposure to the smallest group possible).

Robertson's experience suggested that the use of industrial cleaning materials was increasingly being seen as a potential cause of either sensitiser-induced or irritant-induced occupational asthma. This was supported by the European literature that confirms that cleaning is an under-recognised high-risk occupation, and that the numbers affected are increasing. "There are no good studies on cleaning materials [yet]," Jaakkola says, "but now that the high risk for cleaners has been identified, I suspect that research will identify more traditional sensitisers, like glutaraldehyde, in these materials. And since cleaning materials appear to contain both sensitisers and irritants, we'll see synergistic effects; for example, individuals are likely to be more easily sensitised if irritants are also present."

In several of the cases Robertson described - workers sensitised (or otherwise affected) in metal grinding (cobalt allergy), soldering (colophony) and nursing (glutaraldehyde) and in brewing and X-ray work (unspecified agents) - workplace visits revealed that measures taken to prevent/mitigate exposure (such as use of respiratory protective equipment) were often not effectively applied; for example, a respirator being used without a filter cartridge in place. Measures designed to reduce occupational asthma risk have to be strictly applied, Robertson said: "Unfortunately, many health and safety officers look at their workplaces through rose-tinted glasses."

Financial loss and the "sad" UK situation

A main theme of Robertson's presentation was the extent to which occupational asthma sufferers in the UK also suffer financial loss as a result of their work-related ill health. In the large majority of cases this was so, Robertson said, most commonly because exposure cannot be adequately controlled and the individual either has to be removed from exposure - often by changing their job - to avoid asthma symptoms. A major review of 138 UK cases found that exposure control was impossible and relocation (often to a less well-paid work) was necessary in all but 16 cases.

It was a "sad comment" on the situation in the UK, Robertson noted, that in cases where the individual is unwilling to bear the loss of income and it is impossible to implement the best-choice prevention strategy (removal from exposure and relocation and/or retraining), the individual may continue to be exposed against the advice of the occupational physician.

Professor Jaakkola contrasts this situation with that in Finland, where benefit mechanisms are comprehensive: "Several speakers at the workshop referred to this type of situation [that Robertson described], where the [UK] occupational asthma sufferer is likely not to get the best treatment, is likely not to have improved working conditions and is likely to suffer financially.

"In Finland, it's totally different. Where there is a clear case of occupational asthma, as the traditional type of SIOA, there are good social insurance mechanisms in place providing for individuals to be compensated, rehabilitated and [if necessary] retrained for another job. Although there is invariably some overall loss of income associated with illness, in cases of clear occupationally induced ill health the sufferer's income is usually maintained close to the pre-existing level.

"And the Finnish occupational physician is less likely to face the dilemma of dealing with a sensitised individual who wishes to avoid financial loss and continue to put up with a level of asthma symptoms. As elsewhere in Scandinavia, there are independent, third parties (bodies or individuals, usually panels) that make decisions about difficult cases presented by clinicians. This is done in a systematic way, policies being adopted for different diagnoses. These cannot be applied in a mechanical way, of course, but policies are adopted for all occupational diseases which are applied irrespective of the peculiarities of individual cases, or individual workplaces, which might otherwise preclude the best-choice action being taken for the individual's benefit.

"This is in fact what is meant by an evidence-based approach to occupational medicine. You do not just consider the individual, you have a policy based on different types of evidence: what causes the disease? What are the options are for dealing with it? etc."

OH in the Nordic countries

Population-based studies in occupational health are more advanced in Finland and the Nordic countries than in the UK because researchers have good access to well-documented national health databases. "Not only is it easier to do epidemiology but the validity of results is greater, in the area of occupational health and in health in general. It's not the only way to do OH research; very high-quality research is carried out in the UK and the USA where there is no access to such high-quality data, but it's done in other ways," Jaakkola notes.

"In my opinion," Jaakkola says, "the underlying weakness of the British [OH] system is the emphasis placed on providing treatment while too few resources are directed at doing risk and exposure assessments." Jaakkola refers to the limited demand from smaller employers for general occupational health services. At the workshop, Dr Laurie Latham, chief occupational health physician at the Midlands Occupational Service Ltd, which provides occupational health services to small and medium-sized employers in the Black Country, had described how difficult it was to market managed occupational health programmes in the area as opposed to piecemeal pre-placement, job-specific or regulation-driven health surveillance services. "There has been little progress in recent years", Latham has said.

"The Nordic countries, of course, have two significant advantages," Jaakkola says, "occupational health services are provided within primary healthcare (and required by law) and there are strong OH institutes linked to the social security system. The Finnish IOH and its sister institutes in other Nordic countries have a tradition of high-quality research and publishing services.

"The resource comparison with the UK is stark," Jaakkola goes on. "Although Finland has a similar population to that of the West Midlands, the Finnish Institute of Occupational Health has a staff of 800 compared with the Birmingham Institute's 20."