Between the 1890s and the 1970s, a Pennsylvania company initially known as Ehret Magnesia Manufacturing Company and later as Baldwin-Ehret-Hill was a major manufacturer of asbestos products that were widely used in construction and in war production between 1940 and 1945. In addition to asbestos insulation blocks, the Ehret company was known for two varieties of pipe insulation: Thermolite and Durocel (which has nothing to do with the brand of electric battery).
Thermolite was a compound of magnesium oxide, also known as “magnesia” or periclase, and amphibole asbestos – a particularly deadly form that is the only known cause of mesothelioma. Those who worked in the manufacture of this product are as much at risk for mesothelioma as those whose trades took them into shipyards, building crawlspaces, and furnace and boiler rooms, or served aboard naval ships or on the crew of other sea-going vessels on which Thermolite and similar products were used.
The asbestos insulation blocks were used directly under roofs of structures and around furnaces, boilers and anywhere else heat and flame was a safety concern. Such block insulation was in use as late as 1975.
In addition to these industrial applications, Ehret products have turned up in Valley Forge National Park , where the company dumped its asbestos waste for eighty years with the permission of the state government. Shockingly, no action was taken to deal with the contamination until 1997, when the Environmental Protection Agency (EPA) closed that part of the park off to public access and began taking emergency action to contain the hazard.
The “blue” crocidolite and “brown” amosite varieties of asbestos used in Ehret products are especially deadly; relatively long, hard and sharp, these fibers are essentially microscopic needles that once breathed, begin the process of burrowing through lung tissues from the inside out. As they make this gruesome journey, they cause mutations in cellular DNA that causes the cells to become malignant. Medical researchers have not yet determined the exact mechanism by which this occurs, but this exposure to amphibole asbestos remains the only known cause of mesothelioma.
It is one of the great ironies of history that a substance responsible for saving so many lives is responsible for nearly as many deaths. Ehret products were not the only forms of asbestos insulation used before, during and after the Second World War. Raybestos, Johns-Manville and W.R. Grace were also major suppliers; it was the highly lucrative nature of these government contracts that led these corporations to suppress information regarding the health hazards of asbestos, all of which were well known by 1940.