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Occupational Medicine 2015;65:6–14 doi:10.1093/occmed/kqu175 In-depth review Working with asbestos and the possible health risks D. Sen Centre for Occupational and Environmental Health, University of Manchester, Manchester M13 9PL, UK. Correspondence to: D. Sen, Centre for Occupational and Environmental Health, University of Manchester, Oxford Road, Manchester M13 9PL, UK. E-mail: [email protected] Background The generic term asbestos refers to a group of crystalline mineral silicates that occur naturally in various forms. Because of their properties of strength, heat and electrical resistance and their ability to withstand corrosion by acids and sea water, asbestos was used extensively both in the UK and worldwide. Aims To provide a historical perspective of this ubiquitous occupational hazard, consider the key changes in UK legislation aimed at improving the management of this occupational health risk and describe the evidence from the scientific literature concerning asbestos and disease. Methods Original articles, reviews (including reference textbooks) and scientific literature in PubMed and other principal medical science databases, 1960–2014, were searched. Publications by regulatory agencies and by governmental organizations were also considered and included where relevant. Results Asbestos remains the biggest cause of cancer deaths worldwide. For malignant mesothelioma deaths alone, it is estimated that in the UK, between 2015 and 2020, the number of cases will peak at 2500 cases annually. It is not clear whether there is a safe level of asbestos fibres in air. Evidence for the efficacy of health surveillance is lacking. Conclusions Although the use of asbestos was banned in the UK in 1985 (amosite and crocidolite) and 1999 (chrysotile), it remains a significant occupational risk factor for work-related morbidity and mortality, causing both benign and malignant diseases, often with long latency. Further research is needed regarding exposure levels and health surveillance. Key words Asbestos; asbestosis; long latency; lung cancer; mesothelioma; screening. Introduction Asbestos is a generic term for a group of crystalline mineral silicates that occur naturally in various forms. They result when siliceous minerals are leached out of rock by water and then re-crystallize in spaces within the parent rock as compound metallic silicates. There are various morphological types that differ in their mechanical, chemical and toxicological properties [1–3]. Table 1 lists those that come under the term ‘asbestos’ as defined in Regulation 2 of The Control of Asbestos Regulations 2012 [4]. Any mixture that contains one or more of these fibres at more than trace amounts is within the definition. Debris containing asbestos is also covered by asbestos legislation [4]. Asbestos is resistant to heat and other means of destruction. Its fibrous nature enables it to be woven into cloth, incorporated into cement materials, ceiling tiles, brake and clutch linings, flooring, resins, polymers and © Crown copyright 2015 filter papers. In the 19th and 20th centuries, asbestos was regarded as safe and widely used in a large number of industries with minimal control of exposure. From 1950 to 1985, it was extensively used in construction and ship building for insulation and fire protection and for friction materials and filters. Any building constructed during this period is likely to contain some type of asbestos-containing material, which is possibly the most important cause of inadvertent exposure to asbestos. In the UK, asbestos of any kind has not been used in manufacturing since 1999 but may be found (managed or removed), sometimes accidentally, during other work activities in connection with repair and maintenance or refurbishment. Historically, the three main types of asbestos commonly used in industry were: •• chrysotile, commonly known as ‘white asbestos’, and consisting of bundles of soft, flexible fibres several centimetres long, serpentine (morpholo gically curved) fibres; D. Sen: Asbestos Workers and Their Risks 7 Table 1. Morphological types defined as ‘asbestos’ in Regulation 2 of The Control of Asbestos Regulations 2012 Asbestos actinolite Asbestos grunerite (amosite) Asbestos anthophyllite Chrysotile Crocidolite Asbestos tremolite CAS No. 77536-66-4 CAS No. 12172-73-5 CAS No. 77536-67-5 CAS No. 12001-29-5 CAS No. 12001-28-4 CAS No. 77536-68-6 •• crocidolite, commonly known as ‘blue asbestos’, consisting of shorter, stiffer, straight fibres; •• amosite, commonly known as ‘brown asbestos’ and consisting of coarse, straight fibres of iron magnesium silicate. As a naturally occurring fibrous mineral, asbestos is generally grouped into two classes, which differ significantly in terms of their physical and chemical properties. The serpentine class, which includes chrysotile asbestos, are more easily cleared by mucociliary action and broken down. The amphibole class, which includes amosite, crocidolite, tremolite, actinolite and anthophyllite asbestos, are more resistant to clearance from the body, with a longer residence time [5]. Of the three types most commonly used, and now found in construction work (chrysotile, amosite and crocidolite), all cause severe health effects, although amosite and crocidolite fibres are recognized as being more dangerous to health than chrysotile [1,6]. All people who have worked with asbestos are potentially at risk of developing asbestos-related lung disease. Health effects characteristically take many years to develop and people exposed to asbestos often develop lung disease in later life, including in retirement, due to exposure many years previously. Asbestos is currently classified by the International Agency for Research on Cancer (IARC) as a group 1 (‘definite’) human carcinogen [7]. Historical perspective One of the first suggestions that exposure to asbestos could cause lung disease was at an industrial disease board enquiry in 1899. Cases of lung fibrosis were recognized as being associated with asbestos in the early 20th century, soon after the start of mining and exploitation of the mineral ore on an industrial scale, but were masked by the high incidence of tuberculosis. In the early 1950s, epidemiological evidence identified an increased risk of lung cancer from exposure to asbestos in the British textile industry and the risk to shipyard workers was also recognized [1,8]. By the end of the 1960s, a case–control study in South African miners showed an association with mesothelioma and asbestos exposure [9]. It was also shown that the excess of lung cancer that occurred in many cases of exposure to asbestos fibres reflected an interactive effect of asbestos and tobacco smoking [1,8,10]. The Asbestos Survey was established in 1971 to monitor the long-term health of workers covered by the regulations to control occupational exposure to asbestos [11]. Workers were recruited during, initially, voluntary and then statutory medical examinations. During the medical, a brief questionnaire was completed with the consenting worker and they were then flagged for death registrations. The results from 1971 to 2005 were published in 2009 [11]. There were 15 496 deaths among the 98 912 workers included in the analysis. All-cause mortality was significantly higher than in the general population. Known associations between asbestos exposure and mortality from lung, pleural and peritoneal mesothelioma and asbestosis were confirmed. Insulation workers, stripping/removal workers and those employed in manufacturing asbestos cement had the highest mortality from asbestos-related disease. In addition, >50% of asbestos workers were current smokers at the last recorded medical examination, substantially higher than the percentage of smokers in the UK population. Mortality among smokers was higher than among non-smokers, and some of the excess deaths among asbestos workers were attributable to smoking. A recent large-scale report has presented an updated overview and estimate of the current and future burden of occupational cancer in Great Britain, based on recent and current occupational exposures [12]. Lung cancer and mesothelioma are recognized as important cancer sites for both men and women in the overall burden, attributable to specified occupational carcinogens in the UK. Asbestos contributed the most to both total deaths attributable to occupational exposure and to cancer registrations (larynx, lung, mesothelioma, stomach). There are several key exposures which give rise to substantial exposures across multiple industry sites. Of particular note is exposure to asbestos in construction, personal and household services, land transport and mining. Legislation The Asbestos Regulations 1969 were passed with the goal of managing exposure to the dangerous fibres, and in 1972, there was a voluntary ban on the use of crocidolite. In 1983, the Asbestos (Licensing) Regulations required a Health and Safety Executive (HSE) licence for any person working with asbestos coating or asbestos insulation products. This was followed in 1985 by the UK’s Asbestos (Prohibition) Regulations, which sought to ban the import or use of the more dangerous forms of asbestos, namely crocidolite (blue asbestos) and amosite (brown asbestos). In 1987, the Regulations of 1969 were replaced by the Control of Asbestos at Work Regulations, which aimed to ensure tighter controls, focusing on the prevention of exposure to asbestos while at work [13]. 8 Occupational Medicine The Control of Asbestos at Work Regulations 1987 introduced, in Regulation 16, the statutory requirement for medical surveillance and the maintenance of health records. The asbestos employer was required to maintain a health record for each of their employees exposed to asbestos above a specified action level. Each employee exposed to the hazard in this way was required to have medical surveillance not >2 years before the beginning of such exposure and periodic medical examinations at intervals of not >2 years while exposure continued. Each medical examination included a specific examination of the chest and employees were issued with a certificate stating that they had been examined. The 1987 Regulations were repeatedly amended. In 1992, some usage of white chrysotile asbestos was added to the prohibition law from 7 years earlier, which had related to usage and importation of blue and brown asbestos only [14]. In 1993, the Regulations of 1987 were amended to necessitate the substitution of any material containing asbestos. In the 30 years between 1968 and 1998, it is estimated that 50 000 people died in the UK from asbestos-related diseases [15]. Asbestos was responsible for more occupationally induced deaths than any other single cause. It was recognized that as asbestos could result in death 15–60 years after exposure, the mortality rate would be expected to rise until at least the year 2010–20 and was largely determined by the level of exposure before the introduction in the 1980s of relatively stringent asbestos legislation. It was also recognized that around one quarter of those dying had once worked in the building and maintenance trades—where people can be exposed, often inadvertently, to asbestos during work. The then Health and Safety Commission (HSC) was concerned that information on whether buildings have asbestos in them was not always passed to those at risk. The Control of Asbestos Regulations 2002 required a new level of protection for those working in buildingrelated trades and others at risk from asbestos in buildings, by a duty for those with responsibilities for the repair and maintenance of non-domestic premises to manage asbestos. It required them to find out if there were asbestos-containing materials within these premises, to record the location and condition of such materials, and then assess and manage any risk from them, including passing on information about their location and condition to anyone liable to disturb them. The regulations applied to all people with a duty to manage the risks from asbestoscontaining materials in premises: building owners, tenants and anyone else who had any legal responsibilities for workplaces. The two Approved Codes of Practice (ACoP) that supported these regulations were revised also, introducing improved requirements for the provision of training and for clearance procedures following asbestos work. Most recently, in 2006, all previous laws on the control of asbestos, including prohibition and licensing regulations, were rolled into the all-encompassing Control of Asbestos Regulations 2006, which came into force on 13 November 2006 together with the associated Code of Practice: Work with materials containing asbestos (First edition 2006) [16]. The earlier codes of practice for work with asbestos were withdrawn. For the purposes of these 2006 regulations, work with asbestos now included the removal, repair or disturbance of asbestos, any work ancillary to and associated with this and supervision of such work and any associated ancillary work. The Control of Asbestos Regulations 2012 came into force on 6 April 2012, updating earlier asbestos regulations and fully implementing the European Union Directive on exposure to asbestos (Directive 2009/148/ EC) [3,17]. In practice, the changes are fairly limited though it does mean that some types of non-licensed work with asbestos now have additional requirements, i.e. notification of work, medical surveillance and record keeping. All other requirements remain unchanged. Whether a type of asbestos work is licensable, notifiable but non-licensable, or non-licensed work has to be determined in each case and will depend on the type of work being carried out, the type of material being worked on and its condition, and therefore the risk assessment is key. Full details can be found on the HSE website [18]. Health surveillance and health records Health records and health surveillance are required by Regulation 22 of the Control of Asbestos Regulations, 2012 [4,19]. All employees who undertake licensable work with asbestos (essentially asbestos strippers) and are exposed to asbestos above a defined action level must undergo regular health surveillance by a doctor who has been appointed by the HSE. This must consist of a 2 yearly medical surveillance focussing on the respiratory system, to include a respiratory questionnaire, respiratory examination and lung function testing (spirometry). A chest X-ray (CXR) is not a routine part of the examination and should only be done if clinically indicated. Previous and current exposures must be documented, including details of any occupational hygiene control measures when available. Each employer must keep a health record for any employee who undertakes licensable work as defined by the regulations. The health record must be kept in a safe place for at least 40 years after the last entry put into it or until the person reaches 80 years. It should contain certain key pieces of information, including a record of the types of work carried out with asbestos and where relevant, its location, with start and end dates, average duration of exposure in hours/week and details of any personal protective equipment used. D. Sen: Asbestos Workers and Their Risks 9 The information that the employee provides to the appointed doctor as part of the medical surveillance and any findings or recommendations from the appointed doctor must be documented in a medical record. The medical record should be kept by the appointed doctor as ‘medical in confidence’ in secure storage in line with professional arrangements. By 30 April 2015, all workers carrying out Notifiable Non-licensed Asbestos Work (NNLW) will also need to have a medical examination. Non-licensed but notifiable work is essentially any refurbishment activity involving asbestos—so called ‘white-van-man’ work. Such examinations will then need to be repeated at least every 3 years, as long as the worker continues to do NNLW. After April 2015, workers carrying out NNLW for the first time will have to have an examination before they can start such work. Guidance for doctors conducting these medical examinations is available on the HSE website [20]. Pathology Asbestos is dangerous to health for a number of reasons. The colour of asbestos-containing materials cannot be used to indicate fibre type and/or toxicity and laboratory identification is required. Airborne fibres cannot be seen or smelt. They are characteristically long, thin, respirable particles between 5 and 15 microns long and 0.1 micron thick. They tend to accumulate in the alveoli adjacent to small airways, can lodge and penetrate the alveolar wall. Once in situ, fibres are resistant to destruction, persist in the lung and provoke low-grade inflammation leading onto fibrosis [3,7,10]. Fibrosis causes thickening and some narrowing of the terminal airways. Gradually fibres migrate into the lung tissue between the alveoli causing an extension of the lowgrade inflammation and interstitial fibrosis develops and extends to present as asbestosis. Lung cancer and mesothelioma are recognized sequelae to asbestos exposure. The risk to health is related to both fibre type and inhaled ‘dose’. It is recognized that larger exposures are more likely to give rise to more extensive disease but no low, safe level of exposure has been identified. Expert medical and epidemiological opinion is that there is no threshold level of exposure to asbestos below which there is no risk [1,3,7,21,22]. This is accepted by the courts, as is the benchmark for a ‘significant’ exposure which is defined by the Industrial Injuries Advisory Council (IIAC) as being above normal background levels [23]. As there is a latent period between exposure and illhealth, there are no early health warning signs to alert the exposed person and in some cases, lung changes can continue to develop after exposure has ceased. Asbestos-related health effects Asbestos exposure can cause four basic types of diseases as shown in Table 2. Table 2. Asbestos-related health effects Benign disease Pleural plaques Pleural thickening Benign pleural effusion Malignant disease Mesothelioma Lung cancer Interstitial lung disease Asbestosis Gastrointestinal disease Retroperitoneal fibrosis? Benign pleural disease Pleural plaques Pleural plaques are discrete areas of pleural thickening +/– calcification in the pleura covering the surface of the lung tissue. They are the most common sequelae of asbestos exposure and occur in 20–60% of known exposed workers, with a latent period of 10–30 years post-exposure (prevalence in the general population is 0.5–8%). They are generally asymptomatic, although rarely cause mild dyspnoea (shortness of breath) if they are sufficiently extensive to restrict movement of the underlying lung tissue. Lung function is usually normal and they commonly occur as calcified areas identified on CXR. They do not undergo malignant change but their presence indicates past asbestos exposure [1,2,21,22,24]. The condition does not constitute a prescribed disease for the purposes of Industrial Injuries Disablement Benefit (IIDB). Diffuse pleural thickening Diffuse pleural thickening occurs usually after more heavy exposure and pathologically consists of extensive areas of fibrosis and adhesions [1,2,22,24]. Although often asymptomatic, it can present with chest pain and exertional dyspnoea. It can be associated with restrictive lung function tests and CXR shows extensive shadowing. It is dose related, the more extensive thickening being related to more extensive exposure. It is a prescribed disease. Benign pleural effusion Benign pleural effusion(s) are also dose related, usually after heavier exposure and usually asymptomatic. The latent period between first asbestos exposure and pleural effusions is less than for other asbestos-related conditions. It is usually <20 years but can be <10 years postexposure. There is debate over whether benign pleural effusion can progress to diffuse pleural thickening or mesothelioma. When a tumour does not develop, it is not certain whether the finding is coincidental rather than as a direct progression of the initial pathology [1,2,7,22]. Benign pleural effusion is not a prescribed disease. 10 Occupational Medicine Benign pleural diseases are not themselves precursors of malignant change but, in so far as they reflect exposure to asbestos, they may be associated with an increased risk of asbestos-related pleural malignancy. The relation between benign pleural disease and lung cancer is unclear. On a priori grounds, it seems likely that the risk of malignancy will be more a function of the dose of asbestos inhaled rather than the presence or absence of benign pleural disease. Malignant disease Malignant mesothelioma Malignant mesothelioma is an aggressive, diffuse, fatal, asbestos-associated disease originating from the lining cells (mesothelium) of the pleural (65–70%), peritoneal (30%) or, rarely, pericardial (1–2%) cavities around the lung tissue, abdominal cavity and heart [25]. It has been recognized as an industrial disease since 1960 when the strong causative link with asbestos exposure was confirmed [1,8]. Epidemiological data suggest that the amphibole, crocidolite, is associated with the highest risk of mesothelioma and that the serpentine fibre, chrysotile, has the lowest. Asbestos exposure is the single major cause (>90%); however, there is evidence that mesothelioma may result from both para-occupational exposure, for example women having laundered their husbands’ overalls, and non-occupational environmental exposure [1,25,26]. Idiopathic or spontaneous mesothelioma can also occur in the absence of any exposure to asbestos in both animals and humans and a recent review suggests a rate in humans of around one per million [25,27]. Unlike asbestosis, there is no dose–response relationship with mesothelioma: although the risk is very small at low exposure levels, there is no threshold level below which there is no risk [1,2,22,25]. There is latency between initial exposure and disease of 15–60 years, with a mean of 40 years. One retrospective study found a median latency of 32 years with 96% of cases occurring after at least 20 years [1]. It has been typically a disease of dockyard workers, but other trades are now thought to be at risk including joiners, plumbers, engineers and electricians. The incidence is increasing. The original UK mesothelioma register dataset, which contained all deaths from 1968 to 2001, has been superseded by HSE’s publication Mesothelioma Mortality in Great Britain 1968 to 2012 [28]. It indicates that the annual number of deaths from mesothelioma rose from 153 in 1968 to 2535 in 2012. From the original data, Hodgson et al. estimated that deaths from mesothelioma would peak between the years 2011 and 2015 with between 1950 and 2450 cases annually, but that estimation has had to be modified to a peak in 2020 of around 2500 deaths [28,29]. In 2009, a case–control study of occupational, domestic and environmental mesothelioma risks in Britain concluded that mesothelioma risk is determined largely by asbestos exposure before age 30 [30]. The researchers calculated that men born in the 1940s who worked as carpenters for >10 years before they reached 30 had a lifetime risk for mesothelioma of ~1 in 17. For electricians, plumbers and decorators born in the same decade who worked in their trade for >10 years before they were 30, the risk was 1 in 50 and for other construction workers, it is ~1 in 10. The report also showed a small, increased risk in those who had lived with someone who had been exposed to asbestos. Early diagnosis is crucial as it is a devastating disease both physically and psychologically and most patients will die within a year of diagnosis [1,2,22,27]. Clinically, it usually presents with a pleural effusion, chest pain (usually dull, chest wall pain but occasionally sharp, pleuritic pain) and breathlessness. Radiology will identify the lesions and a histology diagnosis is very helpful for obtaining appropriate compensation. Currently, the British Thoracic Society guideline is that a diagnosis of malignant mesothelioma must be considered in any patient with a pleural effusion or pleural thickening especially if associated with a history of asbestos exposure and chest pain [27]. Though there are several recognized treatment options available, there is little evidence of survival or quality of life benefits. Active, supportive care is essential to include interventions for pain relief, dyspnoea and psychosocial problems. Early diagnosis is essential to reduce suffering, get early adequate support and compensation. It is a prescribed disease as defined by the IIAC [23]. Lung cancer Although 90% of lung cancers are associated with smoking, there is evidence of synergy between asbestos and smoking [1,2,5,8]. Studies suggest that this interaction is not additive, but with a much greater risk of cancer than expected taking both risks into account [1,8,31]. There is no way of distinguishing clinically between primary lung cancer caused by cigarette smoking from those due to asbestos or those due to other causes [1,5]. Medical surveillance provides a very important platform for discussion and education of the employee, to stop smoking and for the employer, to maintain a smoke free environment. The prognosis of lung cancer is somewhat worse in a patient with asbestosis as they may not tolerate surgical or other treatments because of the underlying disease [1,5,21]. In view of the synergism between asbestos exposure and smoking, all asbestos workers, whether they have asbestosis or not, should be strongly advised to stop smoking. Darnton et al. [32] have estimated that since the excess lung cancer risk in heavily exposed workers is likely to be D. Sen: Asbestos Workers and Their Risks 11 of the same order as deaths from mesothelioma, >1 in 10 of all carpenters born in the 1940s may die of a cancer caused by asbestos. Interstitial lung disease—asbestosis Asbestosis is characterized by chronic pulmonary interstitial fibrosis and results from exposure to asbestos [1,2,7,21,22]. It develops after a long latency of 25–40 years post-exposure [1,10,21,22]. There is a dose–response relationship and it is more likely to occur in those with heavier exposures [33]. It is generally accepted that the development of clinically relevant asbestosis requires a cumulative dose of 25–30 fibres/ml air over many years of exposure [1,3,10,22]. Clinically, it usually presents with gradually developing dyspnoea and cough and the presence of basal crepitations (crackles heard on auscultation) and finger clubbing (40%). Smoking increases the severity and rate of deterioration. Up to 40% continue to progress after removal from exposure and this is more likely to occur in smokers [34]. The risk of lung cancer is increased [35,36]. There is no specific treatment or intervention to halt the disease process and treatment can only be supportive in the later stages. Regular medical surveillance of exposed workers is very important for early identification, referral, advice on smoking and removal from exposure. Asbestos fibres cause fibrosis of the lungs (asbestosis) and pleura, and cancers as described above, and have been found in the mesenteric and omental tissue of patients with mesothelioma and in those exposed to asbestos through sources other than their occupation. Therefore, it seems possible that asbestos may be a causal factor for pleural and retroperitoneal fibrosis [38,39]. In 2004, from a case–control study of 43 patients, Uibu et al. [39] concluded that occupational asbestos exposure is an important risk factor for retroperitoneal fibrosis [39]. Screening for asbestos-related disease Screening is the process of detecting disease before it becomes symptomatic. For a screening test to be effective, certain criteria must be met regarding the disease, the proposed test and any treatment that might follow. Two important principles that must be met are that the test should have a high accuracy and be available and affordable; and treatment for the disease(s) must exist and must be effective before symptoms occur, with little risk or morbidity. Several randomized control trials in the 1960–80 screened for lung cancer using CXRs and found no difference in mortality between the screened and unscreened groups. Also, screening for lung cancer using low-dose computed tomography has not been proved to be efficacious [40]. Compensation Gastrointestinal effects The gastrointestinal tract can be directly exposed to asbestos when fibres which are deposited in the respiratory tract following inhalation may be swallowed. Some mortality studies, highlighted in the 1987 IARC review, have suggested that inhalation of asbestos may cause a small increase in the incidence of death due to cancer of the stomach, oesophagus, colon or rectum [7]. However, a meta-analysis of the available evidence in 1999 concluded that though there was a suggestion of an association between asbestos and laryngeal carcinoma, there was no evidence that asbestos increased the risk of carcinogenic effects in the gastrointestinal system following inhalation [37]. Retroperitoneal fibrosis Retroperitoneal fibrosis is a rare disease characterized by the presence of retroperitoneal tissue, consisting of chronic inflammation and marked fibrosis, which often entraps the abdominal aorta, the ureters and other abdominal organs with resulting secondary effects. In ~70% of cases, the aetiology is unknown though case reports and series indicate that it can be induced by different factors: malignant disease, radiation therapy, infections and the use of several drugs such as methysergide [38,39]. Patients with asbestos-related lung disease may be eligible for compensation through IIDB from the Department of Work and Pensions or a civil law claim for damages from the employer(s) under whose ‘control’ exposure occurred. Under the Limitation Act 1980, individuals have 3 years to make a civil claim for personal injuries from the date that they became aware of any serious injury caused by an act or omission by the proposed defendant [41]. Benefits may include Personal Independence Payment which has replaced disability living allowance and Attendance Allowance for those over 65. Various charities can also provide help and support. Some compensation claims involve protracted investigations (especially civil claims) and patients need to be warned about this and supported as necessary. It is important that adequate attention is given to advising and supporting an affected employee. Discussion Asbestos remains the single biggest cause of work-related deaths in the UK. Significant health risks and serious diseases result when fibres are inhaled. There is a large body of available scientific literature, going back to the 1960s, on cohorts of highly exposed asbestos workers from which we have convincing 12 Occupational Medicine evidence of increased mortality from cancers of the lung, peritoneum and pleura, mesothelioma and asbestosis that can be caused by this hazard. However, the evidence is less convincing for cancers in the gastrointestinal tract as well as other restrictive diseases such as retroperitoneal fibrosis. Currently, asbestos is responsible for ~4500 deaths in the UK every year. Although it has been many years since the ban on the use of all forms of asbestos in manufacturing in the UK, two problems remain: asbestos-related diseases do not present immediately after exposure and there is often a latency of many years; and asbestos is present in many buildings and homes constructed before 2000, which often results in accidental or inadvertent exposure to significant levels of airborne fibres when such asbestos materials are disturbed during construction maintenance and/or refurbishment work. Inadvertent exposure to asbestos is a cause of great concern to those affected. The asbestos removal worker is particularly vulnerable but other workers in any trade are at risk when asbestos is disturbed and must be protected. Although the type of asbestos involved and duration of exposure may be known, there is often little reliable information about the level of exposure. These are all important factors in determining the level of risk, but immediate medical surveillance is not the answer. HSE provides guidance on its website on what to do in such situations [42]. An efficacious screening test that could result in early detection of asbestos-related diseases such as lung cancer, malignant mesothelioma and asbestosis and reduced mortality would represent a major advance in combating mortality (and morbidity). Unfortunately, even for lung cancer, the most common cancer worldwide, screening cannot be recommended [40]. There has been much debate about the usefulness of the statutory health surveillance of asbestos workers as required under current UK health and safety legislation. Although screening of workers during their working life alone is unlikely to detect some of the more serious longlatency diseases such as lung cancer and malignant mesothelioma, screening has some benefits [43]. It provides opportunities for workplace interventions to prevent further exposure, referral for non-medical (compensation and disability) services for those with asbestos-related disease, identifies additional groups at risk of asbestosrelated disease and introduces modifications of current exposure conditions, life style factors and smoking cessation when appropriate. Components of the medical assessment should include the histories (especially smoking and lifetime occupational history), physical examination and diagnostic evaluation [43]. Are there any gaps in the evidence base? Two specific areas where there has been insufficient research done, and more would therefore be useful, are, firstly, in relation to finding a reliable health surveillance tool (with high specificity and sensitivity) for the early detection of asbestos-related lung diseases in particular and secondly, to determine whether there is a level of asbestos fibresin-air that might actually be safe for human health. Key points •• Asbestos, sometimes described as ‘the hidden killer’, remains the single biggest cause of workrelated deaths in the UK and possibly worldwide. •• Currently in the UK, asbestos-related deaths each year number 4500 and the peak in the number dying of diseases associated with asbestos exposure is expected to be reached between the years 2015 and 2010. •• Asbestos-related diseases often have a long latency of many years duration, thus making hazard association difficult. •• Disease progression often continues well after exposure has ceased, usually to a serious (asbestosis) if not fatal (mesothelioma and lung cancer) conclusion. •• Treatment options in serious asbestos-related diseases (asbestosis, malignant mesothelioma) are limited. •• With a ban on asbestos usage in the UK, accidental, inadvertent asbestos exposure remains the biggest problem now, particularly in the maintenance, repair and refurbishment of old buildings harbouring asbestos. Second-hand exposure from handling contaminated work clothes should also not be ignored. Conflicts of interest None declared. References 1. Baxter PJ, Aw TC, Cockcroft A, Durrington P, Harrington JM, eds. Hunter’s Diseases of Occupations. 10th edn. London: Hodder Arnold Press, 2010; 990–1010. 2.Currie GP, Watt SJ, Maskell NA. An overview of how asbestos exposure affects the lung. BMJ 2009;339:b3209. 3. Leman RA, Dodson RF. Asbestos. In: Bingham E, Cohrssen B, eds. Patty’s Toxicology. 6th edn. New York: J Wiley & Sons Inc., USA, 2012; 211–256. 4.HSE. The Control of Asbestos Regulations 2012. Statutory Instruments. http://www.legislation.gov.uk/uksi/2012/632/ contents/made (24 June 2014, date last accessed). 5.Nielsen LS, Bælum J, Rasmussen J et al. Occupational asbestos exposure and lung cancer—a systematic review of the literature. Arch Environ Occup Health 2014;69:191–206. 6.Wagner JC, Newhouse ML, Corrin B, Rossiter CE, Griffiths DM. 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