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CONTENTS. Asbestos Exposure in New Zealand PDF
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1 CONTENTS Introduction...5 Part 1 Review of Registrations... 7 Summary...8 Results...9 Categories of Disease...9 Occupation...10 Pleural Abnormalities...11 Asbestosis...12 Definition of Asbestosis used in the Register...14 Lung Cancer...16 Mesothelioma...17 Discussion...18 Part 2 Background to the Registers Formation of the Asbestos Advisory Committee...22 Establishment of the National Asbestos Registers...22 Asbestos Exposure Register...23 Asbestos Disease Register...25 Exposure Index...27 Part 3 Spiral CT Scanning and Lung Cancer Screening Spiral CT Scanning...30 Lung Cancer Screening Trials Comparing CT with Chest X-rays...31 Comparison Data: CT vs CXR...31 Does Early Detection Influence Outcome?...32 Should Asbestos-Exposed Workers Be Screened For Lung Cancer?...34 Recommendation...34 References...35 Asbestos Exposure in New Zealand - 1
2 Part 4 What is Asbestos...37 The Uses of Asbestos...39 Asbestos Use in New Zealand...40 Key Dates in the Health History of Asbestos...42 Asbestos Awareness in New Zealand...43 Part 5 Asbestos Issues Ahead Asbestos Issues Ahead...50 Floor Sanders...50 Asbestos Removal Workers...50 Brake Lining Repair Workers...50 Building Maintenance Workers...51 Demolition Workers...51 Part 6 Miscellany OSH Publications on Asbestos...54 Contact Details...55 Members of the National Asbestos Medical Panel...55 Asbestos Exposure in New Zealand - 3
3 INTRODUCTION The two Asbestos Registers, The Disease Register and the Exposure Register have now entered their second decade, 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 and 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, all support the correctness of the New Zealand Government s initiative in 1990 to establish the Asbestos Advisory Committee which resulted in the Report of the Asbestos Advisory Committee to the Minister of Labour in April 1991 and the subsequent establishment of the National Asbestos Registers in March 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, with current exposure less and largely confined to brake repairers, lino removers, demolition workers, carpenters, electrical, plumbing and building maintenance workers and asbestos removal workers. There are lessons to be learned from this world wide asbestos epidemic, and it is important to remember that high levels of asbestos exposure are still occurring in some parts of the world. The first was 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 in terms of respiratory and general health and that solutions are not complex. They involve the Asbestos Exposure in New Zealand - 5
4 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 work place air on respiratory health will become clearer with diseases such as welders lung, asthma, chronic bronchitis and emphysema being recognised more clearly for their work relatedness. It is thus time to consider expanding the Asbestos Registers to reflect the current situation in the workplace and to rename them the Occupational Respiratory Disease Registers. 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 recent report to the Associate Minister of Labour: The Burden of Occupational Disease and Injury in New Zealand 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 Asbestos Exposure in New Zealand - 6
5 Part 1 Review of Registrations Asbestos Exposure in New Zealand - 7
6 SUMMARY This report reviews notifications made to the National Asbestos Medical Panel for the period March 1992 November A total of 821 cases were reviewed, which included: 155 cases of mesothelioma 77 cases of lung cancer 191 cases of asbestosis 398 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 lung cancer history taking is 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 were: - Respiratory Symptoms and Asbestos Dust Exposure Mesothelioma in New Zealand Lung Function Changes in Asbestos Exposed Workers with Pleural Abnormalities 2000 In addition special reports were published: - Recent Advances in Asbestos Related Disease (Dr M Becklake) The Epidemiology of Mesothelioma in Historical Context (Dr s JC and AD McDonald) 1998 Asbestos Exposure in New Zealand - 8
7 RESULTS The following Figs. are based on the 821 cases reviewed over the period March 1992 to November 2004, and included 155 cases of mesothelioma, 77 cases of lung cancer, 191 cases of asbestosis, and 398 cases of pleural abnormalities. Categories of Disease Fig 1 Catergories of Disease Asbestosis 23% Pleural Disease 49% Lung Cancer 8% Mesothelioma 20% Fig 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. Asbestos Exposure in New Zealand - 9
8 Occupation Fig 2 Occupation p Carpenters/Builders 21% Plumbers, Fitters, Laggers Etc 40% Friction Products 2% Electricians 5% Watersiders 5% Asbestos Sprayers 4% Asbestos Processors 11% Other 9% Non-Occupational 2% No Known Exposure 1% Fig 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% 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 group. 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 asbestoscontaminated clothes. The no known exposure category refers predominantly to mesothelioma cases where conclusive exposure histories were not available. Asbestos Exposure in New Zealand - 10
9 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. 398 cases were reviewed. 387 were Caucasian, 7 Maori, and 4 Pacific Island. All but 3 were males. The mean exposure index was 177, with a range of There were 39 smokers, 244 ex-smokers and 104 never smokers. (Accurate smoking histories were not available in 11 cases.) Fig 3 Occupations 40% 35% 30% 25% 20% 15% 10% 5% 0% Asbestos Processors Asbestos Sprayers Plumbers, Fitters, Laggers etc Carpenters/builders Friction Products Electricians Watersiders Other Non-Occupational No known exposure Fig 3 shows the distribution of pleural abnormalities according to occupation. Asbestos Exposure in New Zealand - 11
10 Asbestosis 191 cases were reviewed, 189 were Caucasian and there was 1 Maori, and 1 Pacific Islander. Males numbered 176. The mean age at diagnosis was 66 (range 37-86); The mean number of years since first exposure was 39 (range 15-71). The mean exposure index was 197 (range ). There were 17 current smokers, 138 ex-smokers and 30 never-smokers. (Accurate smoking histories were not available in 6 cases.) Radiological changes showed 86 with pleural plaques, 13 with pleural thickening and 20 with both. 40% Fig 4 Occupations p 35% 30% 25% 20% 15% 10% 5% 0% Asbestos Processors Asbestos Sprayers Plumbers, Fitters, Laggers etc Carpenters/builders Friction Products Fig 4 shows the distribution of pleural abnormalities according to occupation Electricians Watersiders Other Non-Occupational No known exposure Asbestos Exposure in New Zealand - 12
11 Fig 5 ILO Grading of Asbestos Cases (n=143) ILO Grading of Asbestos Cases (n=133) 0/1 1/0 1/1 1/2 2/1 2/2 3/2 3/3 Of the 191 asbestosis cases, 143 were categorised by ILO classification, others were categorised on the basis of CT, HRCT or pathology where available. Asbestos Exposure in New Zealand - 13
12 Definition of Asbestosis used in the Register An important issue with this disease is What criteria constitute a diagnosis of asbestosis?. The main point of discussion is the difference between a clinical diagnosis of asbestosis and a diagnosis suitable for use in a national database where the inclusion of patients with early disease is desirable. Gilson defined asbestos along the following lines: Significant exposure to asbestos dust ILO Grade 1/0 or above Bilateral crepitations Restrictive Lung Function Pattern The definition of JC Gilson in his review of asbestos-related lung conditions in the ILO encyclopaedia has been chosen by the panel for the reason stated above and is as follows. a) A history of significant exposure to asbestos dust rarely starting less than 10 years before examination; b) Radiological features consistent with basal fibrosis (1/0 and above, ILO 1980); c) Characteristic bilateral crepitations; d) Lung function changes consistent with at least some features of the restrictive syndrome. Gilson notes that not all criteria need to be met in all cases but that (a) is essential, (b) should be given greater weight than (c) or (d). However, occasionally (c) may be the sole sign. Further he notes that although the restrictive syndrome is the commonest pattern (about 40%), in about 10% of cases airway obstruction is the main feature and in the remainder a mixed pattern is seen. In the 191 asbestosis cases: All had a significant exposure history with a mean exposure index of 197 (range ). Mean latency was 39 years, with a range of years. All cases except one were classified as ILO 1/0 or greater by the panel s radiological consultant. (The majority being 1/1 or greater.) Asbestos Exposure in New Zealand - 14
13 Detailed clinical examination results were not always available from the records, thus the presence of crackles was not measurable. Lung function changes are recorded in the Register based on the availability of data either from respiratory laboratories, respiratory physicians, or occupational health nurses. Additional information from HRCT Scanning has led to the recognition of some cases of asbestosis not covered by the Gilson criteria. The numbers in our report are small but confirm that the classical restrictive picture does not dominate, with obstructive, mixed, and normal patterns all occurring. Asbestos Exposure in New Zealand - 15
14 Lung Cancer 77 cases were reviewed, 72 being Caucasian, 3 Maori, 1 Pacific Islander, and 1 other. 75 were males, 2 females. The mean age at diagnosis was 64 (range 42-80) The mean number of years since first exposure was 40 (range 17-62) The mean exposure index was 156 (range ). There were 15 current smokers, 54 ex-smokers, 5 never-smokers and 3 unknown. Background radiological changes showed 5 with lung parenchymal changes, 16 with pleural plaques alone, 4 with diffuse pleural thickening alone and 4 with pleural plaques and thickening. Histological classification revealed 37 squamous cell, 22 adeno, 10 oat cell, 4 undifferentiated, 1 bronchiolar-alveolar, 2 large cell, 1 not stated. Tumour site was as follows: 38 upper lobe (24 squamous, 7 adeno, 3 oat, 1 large cell and 3 undifferentiated), 26 lower lobe (10 squamous, 14 adeno, 2 oat), 6 middle lobe (all squamous), and 7 not stated. 60% 50% 40% 30% 20% 10% 0% Fig 6 Occupations Asbestos Processors Asbestos Sprayers Plumbers, Fitters, Laggers etc Carpenters/builder s Friction Products Electricians Watersiders Other Non-Occupational No known exposure Fig 6 shows the distribution of lung cancer by occupation Asbestos Exposure in New Zealand - 16
15 Mesothelioma 155 cases were reviewed, 147 being Caucasian, 5 Maori and 3 other. 145 males and 10 females. The mean age at diagnosis was 63 years (range 35-89). The mean number of years since first exposure was 42 (range 12-74). The mean exposure index was 200 (range 1-780). There were 16 current smokers, 87 ex-smokers and 39 never-smokers (information was not available for 13 cases). The three categories: Asbestos processors, plumbers/fitters/laggers, and carpenters/builders, comprised 64% of all registered cases. It has been noted that an asbestos exposure history may be lacking with mesothelioma cases. Our experience suggests that with patience and a recognition of the range of likely exposures, it is often possible to obtain evidence of asbestos exposure. In one case the disease developed in a middleaged woman living in a small rural town. It was revealed that as a teenage girl she had washed the clothes of her older brother who was an apprentice in a railway workshop. Asbestos lagging was used in the repair and maintenance of the boilers, and apprentices frequently had snowball fights with the asbestos. 60% 50% 40% 30% 20% 10% 0% Asbestos Processors Asbestos Sprayers Plumbers, Fitters, Laggers etc Carpenters/builders Fig 7 Occupations Fig 7 shows the distribution of mesothelioma by occupation Friction Products Electricians Watersiders Other Non-Occupational No known exposure Asbestos Exposure in New Zealand - 17
16 Discussion It is recognised that the information recorded in the Disease Register underestimates the total burden of asbestos related disease in New Zealand. This is a consequence of the voluntary nature of the Register, the lack of understanding of work as a factor in disease causation by the medical profession and the failure of the Cancer Registry to code occupation in their data base. Nevertheless the Disease Register has served a useful purpose. There is a greater awareness of work as a factor in disease compared with 1992 when the Registers began. OSH has a greater commitment to the importance of occupational health, ACC employs a greater number of occupational doctors, and there is an increasing number of occupational nurses and safety officers working in the private sector. While it would be unreal to see these developments as directly arising from the activities of the Asbestos Registers, the Registers as part of the wider NODS scheme operated by OSH have in the view of the medical panel played an important part in encouraging these developments. Pleural Plaques One of the aims of the medical panel was to confirm the view that pleural plaques were not just a marker of exposure but represented a disease state. The publication, Lung Function Changes in Asbestos Exposed Workers with Pleural Abnormalities, in 2000, indicated a clear dose response pattern with a reduction of FVC and FEV1 with increasing asbestos exposure and independent of smoking habit. Asbestos The increasing use of HRCT has resulted in the identification of minor degrees of asbestosis often with few if any symptoms and no disability. It is possible that these individuals will have a better long term outlook although this is not yet established. Lung Cancer The contribution of occupational asbestos exposure to the causation of lung cancer is well recognised as being underestimated and incorrectly attributed to smoking. One approach to this issue is to determine a ratio between mesothelioma and lung cancer on the grounds that most mesotheliomas are diagnosed and the majority are seen as caused by asbestos exposure at work. Kjellstrom in a recent paper on this issue noted that estimates can range from between 1 and 10 in other countries with the most likely ratio being 2. Thus one can postulate that a much higher number of asbestos caused lung cancers are occurring than is currently being recorded in the Register or as pointed out by Kjellstrom, being accepted by the ACC. Asbestos Exposure in New Zealand - 18
17 Mesothelioma Reported cases of mesothelioma have accelerated in New Zealand over the past decade as illustrated in the graph below. Unfortunately to date treatment of this rapidly fatal disease is unsatisfactory. 70 New Zealand Cancer Registry Incidence of mesothelioma in New Zealand Conclusion Asbestos related occupational disease continues to disable and kill workers in New Zealand. The extent to which this is occurring can only be estimated but it could be in the vicinity of 200 or more each year. When this disease is put into perspective as part only of the total burden of occupational respiratory disease due to work it is clear that a major task lies ahead to clean up dirty workplace air. With the ban of smoking in the workplace the true extent of non-smoking related occupational respiratory disease will become increasely apparent. Recommendations 1. The panel is of the view that the time is appropriate for extension of its functions to include all occupational respiratory disease. 2. The panel recommends that OSH should take the initiative to provide general practitioners with a useful guide to recognising the work factor in illness. 3. The panel is of the view that teaching of the work factor in illness should be integrated into the teaching of clinical medicine generally in the medical schools in New Zealand. Asbestos Exposure in New Zealand - 19
18 Part 2 Background to the Registers Asbestos Exposure in New Zealand - 21
19 BACKGROUND TO THE REGISTERS The National Asbestos Registers were established in March 1992 in line with the recommendations made to the Minister of Labour by the Asbestos Advisory Committee. Formation of the Asbestos Advisory Committee The Asbestos Advisory Committee was established in October 1990 as an ad hoc body to report to the Minister of Labour on issues relating to the health effects and use of asbestos in New Zealand, adequacy of controls and legislation, and clarification of the legal entitlements available for affected workers. This followed increasing public concern about the past and present effects of asbestos on workers, former workers and their families. Establishment of the National Asbestos Registers Recommendation 4 of the Report of the Asbestos Advisory Committee to the Minister of Labour advised: That an asbestos medical register be established for people who have been significantly exposed to asbestos. OSH should be the organisation responsible for establishing, maintaining and funding the medical register. The medical register should be in two parts: Part 1 Those notified as having been exposed to asbestos; Part 2 Those notified as having an asbestos-related disease. The system should allow movement of the name of a registered person from part 1 to part 2 of the register when indicated. Notifications to part 1 of the medical register were to be made by those who felt that they had been exposed to asbestos, or by people acting on their behalf (and following consultation) such as an employer, union official, relative or friend. Notification to part 2 of the medical register would be done by medical practitioners. A Notifiable Occupation Disease System (NODS) was established in 1992 and asbestos registers have been incorporated in that scheme. This was in accordance with recommendation 5 of the Asbestos Advisory Committee. Asbestos Exposure in New Zealand - 22
20 Asbestos Exposure Register Exposed Person notifies Register Information Booklet posted Form sent by Registrar Data Coded symptoms, work history, smoking history The Occupational Safety and Health Service of the Department of Labour (OSH), in association with the Electricorp Production, undertook an extensive advertising campaign in March and April Advertisements were published in all of the major newspapers, and several trade magazines. The interest generated as a result of this campaign has ensured a high response rate for the exposure register. Notifications have been made by individuals, trade unions, occupational health nurses, doctors, the Asbestos Diseases Association of New Zealand and by some larger companies. Notifications are directed to branch offices of OSH or directly to the Registrar. In recommendation 4, the committee had envisaged that people wishing to be recorded on the asbestos exposure register would have their exposure assessed at an OSH branch. Only those people who were judged as having had significant exposure would then be recorded on this register. However, the huge response from those individuals who had been exposed made it impractical to screen registrants in this fashion. Once a person has notified OSH that they have been exposed to asbestos, an asbestos exposure registration form is sent. The registration form collects information about the individual, their work exposure to asbestos and the state of their respiratory health. Asbestos Exposure in New Zealand - 23
21 When the form has been completed and returned to the Registrar the details are recorded on a database. The individual is then sent a copy of a special publication, Asbestos - A Deadly Dust, which is dedicated to asbestos and its associated health problems. If the person indicates that they have a family doctor, the doctor is informed that their patient has been included on the Asbestos Exposure Register, and is sent a copy of OSH s booklet Asbestos Exposure and Disease: Notes for Medical Practitioners. Asbestos Exposure in New Zealand - 24
22 Asbestos Disease Register Patient notified to Register Confirmation of diagnosis sent to patient and patient s Doctor Information collected clinical, occupational, x-ray, lung function Information reviewed by medical panel Tenders for the National Asbestos Medical Panel were called for in A tender was accepted on 31 October The successful tender came form the group listed below: Dr R Armstrong, Professor R Beasley, Dr J Crane, Associate Professor W Glass, Dr D Jones, Dr N Pearce Dr Beasley retired upon his appointment as Professor of Medicine at the Wellington Clinical School. Dr Crane joined the national Occupational Asthma Panel. Dr D Fishwick joined the panel in He was subsequently appointed to a position in the United Kingdom. The first meeting of the panel was held in February Associate Professor Glass was nominated as the panel s convenor. The following members were appointed to the National Asbestos Radiological Panel: Dr Paul White, Dr George Foote, Dr Graeme Anderson The Registrar from 1991 to 1996 was Mr Craig Eades. From 1996 to 1998 the position was held by Ms Nicola Holden, and later in the year by Ms Andrea Eng until 1999 when Ms Louisa Thomas was appointed. In 2002 Ms Jenny West was the Registrar with Mr Dougal McNeill Registrar in Asbestos Exposure in New Zealand - 25
23 Processes for Registering People Notifications for the register came from two major sources. The first from doctors whose patients had been diagnosed, or were suspected of having, an asbestos-related disease. The second source of notification was from the individuals themselves. Once a notification was made to the Registrar, and consent has been gained from the person concerned, relevant medical records and a full occupational history were obtained. Data Collection The data collected included a medical history, an occupational history, chest x-ray, CT scan where available, lung function tests, and pathology reports. The procedure was as follows: On notification being received by the Registrar: a) An occupational health nurse would visit the patient and carry out a health interview, a detailed occupational and social (including smoking) history. b) Relevant medical reports were obtained from general practitioners and physicians. c) A recent PA chest x-ray was obtained, and in all cases was read by a radiologist according to ILO (1980) guidelines. CTs were used where available, and on occasions requested. d) Lung function data was obtained from physicians reports or requested from respiratory laboratories. Where this was not possible, results were obtained from a test carried out by an occupational health nurse, using a portable spirometer. e) Pathology and post mortem reports were reviewed where available. Asbestos Exposure in New Zealand - 26
24 Exposure Index D = A x B x C Exposure Index Years Intensity Degree This is calculated for each job and total exposure is the sum of each D. Data assessment The National Asbestos Medical Panel reviewed the information obtained, calculated an exposure index (see below) and correlated the medical data. Exposure index An exposure index (D) was calculated from the product of years of asbestos exposure (A); intensity of exposure, using a 1-5 grading according to job category (B); and degree of exposure, using a 3 point grading (C). Guidelines for calculating this index are shown below. A = Total years of exposure in any one job B = Job intensity as follows Mining, milling and processing = 5 Boiler/lagging, rail carriages, shipyard, spraying insulation = 4 Asbestos cement products, construction, demolition, removal = 3 Electrical, friction products = 2 Loading, driving, environmental = 1 C = Degree of exposure (unprotected) Continuous (>50% of work) = 5 Intermittent (20-50% of work) = 2 Minimal (<20% or occasional) = 1 Asbestos Exposure in New Zealand - 27
25 D = A x B x C for each job Exposure index = sum of all Ds Medical data Relevant respiratory symptoms and signs were recorded from the medical histories, and lung function data was classified into restrictive, obstructive, mixed or normal. Pathology reports were used to confirm mesotheliomas and classify lung cancers. Classification of diagnostic categories On the basis of the foregoing, the cases were placed into a primary diagnostic category of: Mesothelioma Lung cancer Asbestosis Pleural abnormalities (plaques, diffuse bilateral pleural thickening and effusions). Other cancers Obstructive lung disease without x-ray changes. Asbestos Exposure in New Zealand - 28
26 Part 3 Spiral CT Scanning and Lung Cancer Screening Asbestos Exposure in New Zealand - 29
27 SPIRAL CT SCANNING AND LUNG CANCER SCREENING A consensus report on behalf of the National Asbestos Medical Panel Dr P White and Professor N Pearce 2003, following a Department of Labour. Meeting of interested parties to discuss this issue, Spiral CT Scanning CT scanning (computerized tomography), also known as CAT scanning, is a computerized x-ray examination. It has become an essential medical investigative tool over the past 25 years. CT was developed in the United Kingdom in 1972 and its inventors were awarded the Nobel Prize. It has revolutionized radiology and medicine as it allows the inside of the human body to be viewed with a clarity never before possible. For example, structures tinier than the head of a pin can be seen within the lung. The patient being scanned lies on a sliding table which moves slowly through a ring or doughnut-shaped gantry. Encased within the gantry, an x-ray tube rotates around the patient's body sending x-rays through the body as it turns. The x-rays are then detected by numerous sensors arranged in a circle around the patient. The information collected from multiple points within the patient's body is sent to a computer which combines all the information to create a cross sectional image of the body. The image can be viewed on TV or printed onto film. Each individual CT image corresponds to a thin cross-section of the body. The anatomical detail obtained by CT is of a high quality and by viewing several adjacent images the computer can provide the radiologist with a clear three-dimensional view of the body's internal architecture. Whereas conventional CT collects data intermittently as each individual level in a region is scanned, spiral CT collects data continuously as the patient's body slides slowly through the x-ray gantry. The data collected by spiral CT is thus more comprehensive and can be reprocessed by the computer to give thinner images and a more detailed view. Superb 3D reconstructions, as well as images in other cross-sectional planes can be produced by the computer from the original data to improve diagnosis. Spiral CT scans can be performed more rapidly than conventional CT, which is important if the patient is uncomfortable or restless. The procedure is safe, painless and cost effective and has become the accepted standard technique for the investigation of chest diseases as well as other medical problems. Asbestos Exposure in New Zealand - 30
Asbestos background information This document provides a range of background information about asbestos to help those unfamiliar with the topic to engage with the policy proposals for new regulations covering
Asbestos and other Occupational Lung Diseases in New Zealand: 2012 Annual Report
Asbestos and other Occupational Lung Diseases in New Zealand: 2012 Annual Report 1 4 4 1 1 1 5 2 1 3 1 6 5 3 5 5 6 3 3 7 1. ASBESTOS CEMENT PRODUCTS 2. TEXTURED COATINGS 3. FLOOR TILES, TEXTILES AND COMPOSITES