Distribution of extractable mutagenic activity in steel foundry air particulates of different sizes.

An Andersen 2000 sampler was used to collect different size classes of airborne particulate matter in a large steel foundry. When extracts of these particles were assayed for mutagenicity using the Ames Salmonella/S-9 assay, much of the mutagenic activity was found in particles of respirable size. Furthermore, mutagens requiring activation were distributed among the various size classes roughly in proportion to the total surface area of the particles with the smallest class (less than 1.1 micron) containing by far the largest amount of mutagenic activity. The distribution of direct-acting mutagenic activity was more variable and in some samples the bulk of this activity was in the largest size class (greater than 7.0 micron).