Study of the secular trend in asbestos bodies in lungs in London 1936-66.

Thick sections (30mu unstained) cut from blocks of lung tissue from 100 consecutive necropsies for the years 1936, 1946, 1956, and 1966 at the Archway Hospital, London, have been searched for asbestos bodies. The incidence rose progressively-0, 3, 14, and 20% respectively. The rise was not explained by the increasing age of death in the later years or by the likely effects of changes in the areas within London in which the deaths occurred. There was no similar increase in the incidence of other bodies in the lungs which might be mistaken for asbestos bodies. The rising incidence is shown to fit reasonably with a model based on the hypothesis that the risk of inhaling asbestos increases in relation to the cumulative total of asbestos imported into the country from 1910 onwards. The rising incidence does not fit a model in which the risk depends simply on the current level of asbestos imports.