Asbestos, while no longer mined or processed in the United States was for over a century the preferred insulating material used in the industrial plants, shipyards, foundries and power stations in North America and elsewhere. One of the most common places asbestos could be found was on board ships, because the insulating properties of asbestos made it ideal as a wrap for steam pipes, which reduced heat loss and made these vessels more economical to operate.
Stevedores are longshoremen who load and unload cargo from large ocean-going vessels. This cargo is often stored in the ships holds where there is very little moving air, and any particulates that are present are allowed to settle onto the cargo and the floor. Much like rats became trapped on ships and transported to the four corners of the globe, so asbestos particles became concentrated on these vessels. Asbestos products were shipped across the ocean to be used as insulating blocks, ceiling tiles and wallboards, and the ships themselves were often made with fireproof doors and boiler room panels containing asbestos.
The stevedores and dockworkers that frequently boarded these vessels were exposed to free-floating asbestos fibers and over the years many of them built up a considerable amount of asbestos in their lungs. Dockworkers also assisted in the installation of new equipment on board ships and were constantly exposed to the sweeping up of collected dust and soot on these vessels. Stevedores inadvertently brought microscopic fibers home in their clothing, hair and shoes, exposing their family members to these tiny particles of silicate mineral.
Thousands of dockworkers complained of respiratory problems associated with asbestos inhalation, and often they died from cancerous illnesses which were finally attributed to the asbestos itself. After most of the manufacturing industry stopped using asbestos in their work environments, people continued to show symptoms of mesothelioma, asbestosis and other lung cancers because asbestos fibers can lay dormant inside a person for decades. As many as 30% of South African stevedores who transported crocidolite asbestos were diagnosed with asbestosis, a potentially fatal scarring of the tissue around lungs. Since the medical researchers of the mid 20th century had more than once pointed out the possible connection between asbestos and cancer, this created a legal fury that continues to this day.