Boonville’s documented sites are manufacturing plants rather than power generation, and two of them turned on the same material: phenolic moulding compound, in which asbestos served as a filler.

Toastmaster Inc. / McGraw-Edison ran an appliance plant here. Caterpillar High Performance Molded Products (HPMP) is documented for rubber, friction and brake products, a category where asbestos was used for heat resistance. A second Caterpillar Boonville facility also appears in the record.

Moulded-product work exposes a different set of people than a boiler house does. The dust comes from machining, grinding, trimming and finishing cured material, and it reaches whoever is working nearby — machine operators and finishers rather than only the insulation trades.