Prevention of asbestosis and reduction in lung cancer mortality in asbestos-exposed subjects has occurred in the last generation in the United States. Massive medical evidence compelled the primary industry to quit using asbestos by making use excessively expensive as risks became uninsurable. This lead to successive waves of court awards for liability and punitive damages and settlements negotiated to user workers, co-contaminated workers, and bystanders. Jury awards for mesotheliomas were frequently $1 million, and for asbestosis ranged from thousands to hundreds of thousands of dollars: an effective way to stem an epidemic. Unfortunately widespread substitution of human-made fibers in construction may predestine a repeat performance.
Clinical Recognition of Asbestosis
Asbestosis is a fibrotic disease of the lung from asbestos after a suitable latent period. Cellular infiltrates and fibrosis surround small bronchioles and limit forced expiratory flow to impair pulmonary function. Asbestosis is diagnosed from chest radiographs by diffuse, irregular opacities in the lung fields or by circumscribed or diffuse pleural thickening, which are defined by international criteria.1
Asbestos exposure produces no acute symptoms. Pathological fibrosis of lung or pleura is well advanced when expiratory airway obstruction permits “early diagnosis,” radiographic abnormality follows and only then do workers have breathlessness on exertion, or cough productive of phlegm. Usually asbestosis has incubated for two decades or more from the first exposure; this is called the “latent” period. Asbestos and cigarette smoking synergize to impair function and produce fibrosis and carcinoma.
Although the first use of asbestos by humans is lost in antiquity, it is mentioned by Plinius, who referred to asbestos as immun vivum, “durable linen,” and Roman slaves who worked in these mines grew breathless and died prematurely. Asbestos has properties of incombustibility, durability, and resistance to friction, which have made it useful for insulation and heat protection in modern industry. H. Montague Murray,2 a London physician, recognized a new disease in the badly scarred lungs of an asbestos worker, presumably from a textile factory, who died after a brief illness characterized by extreme breathlessness. Murray connected the workplace exposure to the scarring in testifying before an inquiry at the British Government Commission on Occupational Disability in 1907 and stated hopefully that with the recognition of the cause, he would predict few future cases. His singular finding was ignored until 1924, when Cooke3 described pulmonary fibrosis in a woman who had worked for 20 years in an asbestos textile factory. The illness was widely regarded as a manifestation of tuberculosis, the plague of those times, and thus was largely ignored. Cooke4 also introduced the name “pulmonary asbestosis” as a pneumoconiosis, one of the dust diseases (as named by Zenker 60 years earlier). He suggested optimistically that recognition would lead to prevention.
After further scattered ...