Asbestos, asbestosis, and cancer, the Helsinki criteria for diagnosis and attribution 2014: recommendations

IntroductionAlthough the use of asbestos has been banned in several industrialized countries, many workers continue to be exposed in asbestos repair and removal work, and asbestos is still widely used in various newly industrialized, rapidly developing countries. According to the most recent World Health Organization (WHO) estimates, more than 107 000 people die each year from asbestos-related lung cancer, mesothelioma, and asbestosis resulting from exposure at work (1). The asbestos epidemic is far from over.The expert meeting on "asbestos, asbestosis, and cancer" was convened in Helsinki in 1997 (2) and consisted of 19 participants from eight countries. This meeting had the goal to "discuss disorders in association with asbestos and agree upon state of the art criteria for diagnosis and attribution with respect to asbestos". In addition, questions concerning the surveillance of asbestos-exposed workers were discussed. The resulting consensus report was titled "Asbestos, asbestosis, and cancer: the Helsinki criteria for diagnosis and attribution" (in the current report a shorter name "Helsinki criteria" or just "criteria" will be used). A follow-up expert meeting on new advances in radiology and screening of asbestos-related diseases was organized in 2000 in Helsinki (3).This report summarizes the results of a project, organized by the Finnish Institute of Occupational Health (FIOH), to update the 1997 and 2000 Helsinki criteria documents in view of the new advances in research. It presents the conclusions of a meeting on 10-13 February 2014 in Espoo, Finland, among an international group of experts working to update the criteria.Recommendations from the Helsinki criteria of 1997In the following, recommendations from the Helsinki criteria document of 1997 (and for radiology 2000) are quoted together with commentary by the authors.General considerations"In general, reliable work histories provide the most practical and useful measure of occupational asbestos exposure". "Using structured questionnaires and checklists, trained interviewers can identify persons who have a work history compatible with significant asbestos exposure." "A cumulative fibre dose expressed as fibreyears per cubic centimetre, is an important parametre of asbestos exposure.""Analysis of lung tissue for asbestos fibres and asbestos bodies can provide data to supplement the occupational history.""For clinical purposes, the following guidelines are recommended to identify persons with a high probability of exposure to asbestos dust:* over 0.1 million amphibole fibres (>5 μm) per gram of dry lung tissue or* over 1 million amphibole fibres (>1 μm) per gram of dry tissue as measured by electron microscopy in a qualified laboratory or* over 1000 asbestos bodies per gram of dry tissue (100 asbestos bodies per gram of wet tissue) or* over 1 asbestos body per millilitre of bronchoalveolar lavage fluid as measured by light microscopy in a qualified laboratory.Each laboratory should establish its own reference values."Asbestosis"Asbestosis is defined as diffuse interstitial fibrosis of the lung as a consequence of exposure to asbestos dust." It is noted that neither clinical nor histological features of asbestosis differ sufficiently from those of other causes of interstitial fibrosis to allow confident diagnosis without a history of asbestos exposure or the detection of increased levels of asbestos bodies or asbestos fibres in lung tissue."Asbestosis is generally associated with relatively high exposure levels." It is however noted that mild fibrosis may occur at lower exposure levels and that histologically detectable fibrosis can occur in situations when radiological criteria are not fulfilled."A histological diagnosis of asbestosis requires the identification of diffuse interstitial fibrosis" in technically sound lung samples "plus the presence of either 2 or more asbestos bodies in tissue with a section area of 1 cm2 or a count of uncoated asbestos fibres that falls in the range recorded for asbestosis by the same laboratory. …