NOHSAC Report

Lessons and Conclusions

Criteria for Selecting Specific Exposures of Interest

It is clear that the purpose of exposure surveillance and exposure control surveillance is to inform change, target and assess interventions, and reduce risk, either through direct action or by influencing policy.

New Zealand currently has no national system for collecting workforce or workplace exposure data. In addition, individual agencies responsible for OH&S do not collect current exposure data for use in determining and informing prevention programmes. And while several studies conducted in New Zealand have provided valuable information on workplace exposures, they do not offer a workplace exposure surveillance system to monitor existing and identify emerging hazards.

Ongoing exposure surveillance systems are needed to enable preventive action earlier than is usually possible when monitoring occupational disease and injury. This is particularly true when there is a long latency between exposure and the occurrence of the resulting disorder, as is the case with many work-related diseases such as occupational cancer.

The lack of exposure data for the New Zealand workforce means we cannot:

All exposure surveillance systems require resources for initiation, implementation and operation. The availability of these resources depends on the extent to which the system is embedded within, and in conjunction with, other data collection systems such as outcome-focused health surveillance.

Exposure surveillance systems can operate on a continuous basis in countries with robust infrastructures and expectations for data collection. For example, the USA has no infrastructure for routine and comprehensive data collection, and resources for the NOES are only made available occasionally for limited periods. It appears that exposure surveillance systems continuity and longevity are more likely to be assured when data collection 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. This is because the latter requires less funding and, to a large extent, uses existing resources such as workplace inspectors.

Maintaining exposure databases requires a significant and ongoing commitment to providing resources. In the UK and the USA, for example, databases offer an invaluable resource and knowledge base for regulators and researchers, but they date rapidly without maintenance. In contrast, data are continuously collected and added to databases in Scandinavia and Germany, so the information remains current and is used to inform practice.

Workplace surveys are inherently more flexible to changes in society and less dependent on continuous resource availability.

It is appropriate that Australia and New Zealand draw on the lessons of existing system operators and build approaches consistent with current knowledge and practice. The various approaches used internationally represent a combination of the ideal and the pragmatic; what is essential is that resources for exposure surveillance are made available to collect, maintain and publish data over a period that reflect the latency of the disease and injuries of interest.

Criteria for Selecting Specific Exposures of Interest  

Options for feasible exposure surveillance systems depend mainly on the exposure of interest. The outcomes of interest are still relevant, but primarily in terms of influencing the need for an exposure surveillance system.

Disorders that have a relatively long latency between exposure and occurrence are appropriate candidates for an exposure surveillance system, because the outcome monitoring reflects exposures years beforehand rather than recent exposures.

Using outcome information to plan prevention measures in long-latency conditions means that prevention initiatives are based on historical exposures that may not reflect current occupational exposures. In such situations, monitoring current exposures seems more logical and more likely to lead to faster improvements in OH&S.

As part of the Workplace Hazard Exposure Surveillance Workshop jointly organised by NOHSAC and the OASCC in Sydney in June 2006, criteria were developed for prioritising the exposures that should be the focus of initial exposure surveillance efforts in Australia and New Zealand. These criteria (in no particular order) are:

TABLE 4 Applying the Exposure Criteria to Noise
Long latency/slow onset disease
  • Typically noise-induced hearing loss results from exposure to excess noise (85dB over eight hours over many years)
 
The magnitude of the problem (the number of people affected)
  • New Zealand – $20.000,000 per annum.
  • Australia 2.6 million people have hearing loss in the better ear and 3,545,231 have hearing loss in the worse ear. The data shows that 37% of these have noise-induced hearing loss.
 
The severity of the resulting disease/injury (the extent of impact on individuals/society)

Compared to people with no hearing loss, people with:

  • mild hearing loss are 1.22 times more likely to be unemployed
  • moderate hearing loss are 1.75 times more likely to be unemployed
  • severe or worse hearing loss are 11 times more likely to be unemployed.
 
The absence of adequate data
  • Businesses at the individual level are obliged under law to identify noise hazards and, where present, assess risk. While a standard defines how noise measures should be assessed, there is no certainty that organisations conduct noise surveys, no assurance that the surveys are conducted according to the standard and no process for storing the information centrally. Overall, there is no measure of the nature or extent of exposures.
 
Support exists within the health and safety agencies or workplaces to act on this issue
  • South Australia and New Zealand are interested in noise as a priority, with possible further support from Qld and WA.
 
National exposure standards work (development or revision) currently being undertaken
  • Australian Standard currently under review.
 
The surveillance activity is linked to practicable risk reduction
  • New Zealand and Australia have previously developed excellent noise management resources that are still very relevant. These materials clearly define how to apply noise surveillance data at the workplace level.
 
The surveillance of the hazard and exposure builds and develops the national capacity to understand and act to eliminate
occupational diseases and the processes that generate them
  • The existing control materials provide straightforward guidance on deploying activity around noise. Based as they are on the hierarchy of controls, the concepts and processes for noise control are readily transferable to other hazards.
 
There are agreed/defined methods for assessment
  • New Zealand and Australian standards exist.
 
An established and clear link between the exposure and the disease/injury
  • A dose-response relationship exists between noise exposure and hearing loss. Increasing noise exposures result, in the main, in increased hearing loss.

When these criteria were applied to previously identified outcomes of interest4, a number of hazards and exposures were identified as priorities for exposure surveillance in New Zealand and Australia. These include but are not limited to: