International Review of Surveillance and Control of Workplace Exposures: NOHSAC Technical Report 5
6. Summary and Conclusions
At the outset, this examination of exposure surveillance systems identified a problem with terms such as “exposure”, “surveillance” and “incidence” being used interchangeably and inconsistently. The consequence is misunderstandings of differences between, on the one hand, activities that focus on the surveillance of workplace exposures that potentially result in injuries and disease and, on the other hand, surveillance of injury and disease indicators based on incidence. Thus, in an attempt to draw together an agreed definition for the activities pertaining to surveillance, the term “occupational health surveillance” was used to embrace both “workers’ health surveillance” and “work environment surveillance”. Respectively, these latter terms are used in place of “exposure surveillance” and “injury or disease surveillance”.
It is clear that the purpose of work environment surveillance is to inform change and risk reduction either through direct action or by influencing policy, and various models that explain the role of surveillance are presented. However, the link between surveillance system operation and impact in the workplace is unclear, and there is little evidence of a relationship. Evidence is difficult to obtain given the many co-related factors that influence risk in the workplace.
A range of types of surveillance system are discussed, including administrative registers and statistics, expert assessment systems, questionnaire-based surveys and observational surveys. The relative merits of each are summarised, and the inter-relationships that the different types of systems might have are identified.
Twenty-four work environment surveillance systems have been described and reviewed. A number of these are successful and subjectively assessed as effective by their owners. They provide a robust and up-to-date knowledge base for researchers and regulators to use in targeting interventions and monitoring trends. However, a large number lack continuity and longevity and thus their effectiveness is limited.
Resource demands of the systems limit their operation. All the systems require resources for initiation, implementation and operation, and the availability of these resources depends on the extent to which the system is embedded in and coincident with other data collection systems in the country of operation. In countries were there are robust infrastructures and expectations for data collection, the system managers experience less angst than others where the nature of the work environment surveillance is in some ways alien. In the USA, for example, where there is no infrastructure for routine and comprehensive data collection, resources for the NOES are only made available occasionally for limited periods. Therefore, it would appear that continuity and longevity of work environment surveillance systems are more likely to be assured when the data collection for a system is locked into an existing robust infrastructure.
The significance of such infrastructures is greater where exposure databases are operated and less significant where workplace surveys are undertaken, the latter requiring less funding and, to a large extent, using existing resources such as workplace inspectors.
A significant demand on resources is made by the maintenance of exposure databases. In the UK and USA, for example, these have offered an invaluable resource and knowledge base for regulators and researchers, but they rapidly date without maintenance. Conversely, in Scandinavia and Germany where data is continuously collected and added to the databases, the information remains current and is used to inform practice.
Workplace surveys are more flexible to changes in society and less dependent on continuous availability of resources. The benefit of the approach to surveillance that surveys represent is reflected in their growing use, and it is possible that the growing interest and active promotion of them in Europe signals their significance in the future of work environment surveillance.
The evidence amassed during this review points to the evolution of approaches to surveillance, in Europe in particular, through three “ages” – from outcomes-focused health surveillance systems, through exposure databases containing large numbers of quantitative exposure measurements, to the current age of workforce questionnaire surveys.
It is appropriate that Australia and New Zealand draw on the lessons learned by system operators during these ages and build approaches that are consistent with the current age and the resources that may be available to collect data and maintain the data.