The Relationship between Asbestosis and Bronchial Cancer

Asbestosis is a progressive, fibrotic disease of the lungs caused by inhalation of asbestos fibers. The severity of asbestosis depends on the length of time exposed to the fibers, the amount inhaled, and the specific type of asbestos exposure. There are six different types of asbestos, each naturally-occurring, and each hazardous to lung health. Asbestos lawyers at Pintas & Mullins Law Firm warn the public of the adverse health effects of exposure, and urge anyone diagnosed with an asbestos-related illness to contact our office today for a legal consultation.

A study by the British Journal of Industrial Medicine examined exposure to asbestos dust in association with the additional risk of developing bronchial cancer. Nearly 340 deceased amphibole asbestos miners were subject to the study, which addressed the question of whether bronchial cancer is a side effect of asbestosis or an independent consequence of asbestos inhalation. This correlation was first reported in the mid-1930s, and, in 1966, a study concluded that 12-50% of people suffering from asbestosis also had bronchial cancer.

The amosite mines in South Africa, where the study was conducted, employed the ‘scraper-cleaning’ mining method: Workers sit facing the stone face and drill the amosite out to be scraped and cleaned. This obviously subjects the workers to copious amounts of asbestos dust and consequent inhalation.

The files of the 339 men were searched for details of exposure to asbestos and other mining dust and for smoking habits (number of cigarettes/cigars/pipes recorded in the last clinical examination before death). Smoking was categorized as never a smoker, ex-smoker, and current light, moderate, and heavy smokers. Dose of asbestos was calculated by multiplying the measure fiber levels for each mine, occupation, and time each man had worked there.

Analysis of the data indicates that of the variables of interest, the presence of asbestosis and indices of exposure (years of exposure, residence time, fiber years), the presence of asbestosis was by far the most significant risk factor to being a case of bronchial cancer.

Of the 35 cases of bronchial cancer, 24 were associated with asbestosis. Eleven cases of bronchial cancer occurred in men without asbestosis, and all were smokers. Proportional mortality rates indicated no excess of bronchial cancer in 302 exposed men without asbestosis whereas these rates were progressively raised in men with slight or moderate/severe asbestosis.

This study suggests that asbestos caused bronchial cancer is almost always associated with some degree of histologically demonstrable asbestosis. It must be emphasized that these results should not affect compensation bodies dealing with living subjects exposed to asbestos as slight asbestosis is commonly, and moderate asbestosis occasionally, undetected radiologically.

The question of whether the presence of parenchymal asbestosis is a necessary prerequisite to attribute a bronchial cancer to inhalation of asbestos is controversial. Some authorities believe that the dose of respirable asbestosis dust that will cause bronchial cancer is about the same or even greater than that which will cause asbestosis.

The association between the severity of asbestosis and the prevalence of bronchial cancer is still widely debated. Our understanding of the role of asbestosis in the pathogenesis of cancers in people exposed to asbestos is uncertain at best.

To date, nine key epidemiological papers have been written on whether lung cancer can be attributed to asbestos exposure in the absence of asbestosis. Of the nine papers, two concluded that asbestosis was necessary and seven that it was not. However, the study design, nature and circumstances of exposure and method of analysis of the studies differed considerable, and none was considered definitive. It is probably that the issue may depend critically on asbestos fiber type, an aspect not so far addressed.

It is now fairly well established that the risk of lung cancer is generally much greater after exposure to the commercial amphiboles (crocidolite and amosite) than to commercial chrysotile. If you were exposed to asbestos of any kind and developed an illness because of it, contact a lung cancer attorney immediately to explore your legal rights.

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