Trends in asbestos body counts in bronchoalveolar lavage fluid over two decades

As in most western countries, the use of asbestos has decreased in Belgium since the mid 1970's. Successive regulations have lowered the permissible levels of exposure and prohibited the use of various asbestos products. In order to assess the impact of these prevention measures on the pulmonary fibre burden of asbestos-exposed patients, the bronchoalveolar lavage fluid (BALF) asbestos body (AB) analysis database of the authors' laboratory was reviewed for the period 1983-2000. A total of 4,772 cases were considered, of which 95% were males. AB concentration exceeded 1 AB x mL BALF(-1) in 36.1%. There was essentially no change in the mean concentration of AB over the period evaluated. However, the concentrations in individuals with very high levels decreased over time. This was associated with a shift in exposure categories from primary asbestos workers to those exposed during handling of asbestos-containing materials or to asbestos in place in buildings or industrial sites. This is consistent with epidemiological data indicating that the number of severe cases of asbestosis caused by very high cumulated doses decreases but that benign pleural diseases and mesothelioma remain the most frequent asbestos-related diseases. Past prevention measures are not expected to have a measurable influence on the incidence of mesothelioma in the near future.