Introduction

The two asbestos registers, the Disease Register and the Exposure Register have been in existence for 15 years. When established, certain aims were envisaged.

They were:

1. To raise the awareness of asbestos-related disease nationally.
2. To improve the radiological diagnosis of asbestos disease by using the ILO reference radiographs.
3. To confirm that pleural plaques is a disease and not just a marker for asbestos exposure.
4. To reinforce the importance of patient support groups.

To a large extent these aims have been achieved. The recent publications by Kjellstrom and by Smartt on asbestos-related diseases, and the report in the Australian publication CCH OHS magazine June/July 2004 Asbestos: A Ticking Time Bomb support the correctness of the New Zealand Government's initiative in 1990 to establish the Asbestos Advisory Committee. The committee in turn went on to publish the Report of the Asbestos Advisory Committee to the Minister of Labour in April 1991 and established the National Asbestos Registers in March 1992.

While it is clear that the legacy of disease from working with and exposure to asbestos in New Zealand is continuing and will do so for several decades to come, it is predominantly a legacy from the past. Exposure levels in New Zealand are decreasing and are largely confined to brake repairers, limo removers, demolition workers, carpenters, electrical, plumbing and building maintenance workers and asbestos removal workers.

However, it is important to remember that asbestos exposure still occurs at a high level in some parts of the world and that there are lessons to be learned from what is a world-wide asbestos epidemic.

The first is that there was a general lack of awareness of the effects of inhaling dust at work - regardless of the type of dust - and in spite of the fact that historical evidence went back over 2000 years.

The second was that too great an emphasis was placed on arguing whether the dust was a danger to health or not. Concepts that cement dust was safe and silica dust unsafe or that blue asbestos was worse than white asbestos and so on, distracted governments from the real issue, namely dirty workplace air.

Today we recognise that dirty workplace air is a major problem, both in terms of respiratory and general health, and that solutions are not complex. They involve the putting in place of good general and local exhaust ventilation and providing comfortable and effective respiratory protection. While relatively simple technically, the motive force must be 'the will to do it'.

Finally, the question must be asked of the registers 'where to from here?' It is clear that with the gradual reduction in cigarette smoking among the working population, the impact of dirty workplace air on respiratory health will become clearer with diseases such as welder's lung, asthma, chronic bronchitis and emphysema being recognised more clearly for their relationship to work practices and processes.

It may now be time to expand the asbestos registers to reflect the current situation in the workplace and to include these other occupational respiratory diseases.

Such a move would be in line with the growing recognition by government of the importance and seriousness of occupational disease, a recognition reflected in the 2004 report to the Associate Minister of Labour: The Burden of Occupational Disease and Injury in New Zealand published by NOHSAC (the National Occupational Health and Safety Advisory Committee).

Dr W I Glass (Convenor)
Dr R Armstrong
Dr D Jones
National Asbestos Medical Panel

Part 1: Review of asbestos-related disease notifications

Summary

This report reviews a total of 926 cases notified to the National Asbestos Medical Panel for the period March 1992 to December 2005.

• 164 cases of mesothelioma
• 90 cases of lung cancer
• 205 cases of asbestosis
• 467 cases of pleural abnormalities.

Once again it is noted that the number of lung cancer cases is relatively small compared with mesothelioma cases. This suggests that the taking of a lung cancer history is still dominated by the smoking factor and occupation is ignored.

The transfer of asbestos from the workplace to the home is another emerging feature of asbestos-related disease in New Zealand. Family members are presenting with pleural changes or, rarely and tragically, mesothelioma.

Mesothelioma notifications continue to rise, reflecting exposure in the 1960s and 1970s, and this trend is likely to continue for some years to come.
Three publications have arisen from the registers. They are:

• Respiratory Symptoms and Asbestos Dust Exposure (1997)
• Mesothelioma in New Zealand (2000)
• Lung Function Changes in Asbestos Exposed Workers with Pleural Abnormalities (2000)

In addition two special reports have been published:

• Recent Advances in Asbestos-Related Disease (Dr M Becklake, 1994)
• The Epidemiology of Mesothelioma in Historical Context (Doctors JC and AD McDonald, 1998)

Results

The following figures are based on the 926 cases recorded over the period March 1992 to December 2005:

• 164 cases of mesothelioma
• 90 cases of lung cancer
• 205 cases of asbestosis
• 467 cases of pleural abnormalities.

Categories of disease

Figure 1: Categories of disease 1992-2005

Figure 1 shows the distribution of the four main diagnostic categories: mesothelioma, lung cancer, asbestosis and pleural disease. What is noticeable is that pleural disease is the main category and lung cancer is clearly under represented when compared with mesothelioma.

Notified asbestos disease by occupation

Figure 2: Notified asbestos disease by occupation 1992-2005

Figure 2 looks at occupation for the total number of notified asbestos disease cases. It is clear that carpenters, plumbers and electricians, etc. are together responsible for almost 66 per cent of all cases. These 'all-purpose' construction workers are an occupational category at risk, and particularly so because, unlike asbestos-cement workers, they are not always seen as an obvious risk.

The non-occupational category refers to cases where an individual's exposure was not work-related. This includes all cases resulting from secondary or environmental exposure, such as children brought up in the home of an asbestos worker, and women who wash their husband's asbestos-contaminated clothes. The 'no known exposure' category refers predominantly to mesothelioma cases where conclusive exposure histories were not available.

Pleural abnormalities

This category includes pleural plaques, diffuse pleural thickening, chronic fibrosing pleuritis and pleural effusions. It does not include pleural disease occurring together with mesothelioma, lung cancer or asbestosis.

There were 467 cases reviewed.

• 456 were Caucasian
• 7 were Maori
• 4 were from Pacific Islands
• All but 5 were males
• The mean exposure index was 171, with a range of 6 to 708
• There were 48 smokers, 270 ex-smokers and 115 never smoked. (Accurate smoking histories were not available in 34 cases.)

Figure 3: Distribution of pleural abnormality notifications by occupation

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