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Molders and Asbestos Exposure

Molders are those employed to make and utilize molds for plastics and other polymers. Molders were often exposed to asbestos prior to 1980 when some of the plastics used in the production process contained asbestos fiber.

Molding Processes

Molders are skilled workers who work primarily with the injection molding process. This process is one by which a plastic is heated and then injected into a pre-cast mold. The molders operate machinery that monitors the subtle pressures and plastic cast thickness.

Another process often used is cold molding. Cold molded plastics prior to 1980 were a mixture of asbestos fiber for strength and a polymer cement. During the mixing and molding process for these plastics, an extraordinary amount of asbestos dust could be released into the air around the mixer. While some examples of cold molding that might be visible today utilize a closed system, older machines would have had open hoppers and mixers, as well as unsealed molding chambers. These would also have created an atmosphere full of the various chemicals and additives, including asbestos being injected into the plastic.

In addition to the direct asbestos exposure during the molding and production of these plastic parts, depending on the nature of the part, the molder might then be exposed to the finished product on a daily basis outside of work. With asbestos being such an integral part of daily life prior to 1980, for molders dealing with consumer goods, this was almost certainly the case.

Dangers on the Job

It is accepted that most occupations come with at least some chance of job-related injuries. Even so, most of us in America today expect worker safety to be an important priority of employers, overseen by government agencies. Until relatively recently, however, when it came to exposure to asbestos, employees often toiled without respirators in environments where asbestos dust filled the air.

The Kinds of Asbestos and Their Health Effects

There are two major kinds of asbestos. The most frequently utilized was chrysotile, or the serpentine type. Usually not associated with mesothelioma or asbestos cancer, it is a relatively pliable form of the mineral. Abrasions on the interior surfaces of the lungs can result if serpentine particles are breathed in, however. Asbestosis may be the outcome when abrasions build up in the pulmonary system.

The other classification is called amphibole asbestos; of the two types, it is considered more dangerous to human health. Pleural mesothelioma, an unusual and all too often deadly cancer of the mesothelium (the tissue that lies between the lungs and the chest cavity), is strongly linked with exposure to asbestos, especially the amphibole forms. Extensive contact with amphibole asbestos is also a cause of pericardial or peritoneal mesotheliomas, diseases that damage the lining around the heart and stomach, respectively.

Why Asbestos Was Used

Ironically, asbestos was used when erecting building and in many products because of its ability to save lives. The serpentine form of asbestos is one of the best insulators known when it comes to fire and heat and has been used for this purpose throughout history. The amphiboles had additional traits that made them useful in industry. Amosite, sometimes called "brown" asbestos, for instance, has a high iron content, making it resistant to chemical corrosion. "Blue" asbestos, or crocidolite, was frequently used in areas with electrical equipment since it is highly resistant to electrical current. By combining multiple kinds of fibers, many different asbestos-containing materials (ACMs) could be made that protected lives and property against flames, heat, electrocution and caustic chemicals.

Asbestos did not pose a health hazard so long as it stayed solid. A disadvantage of ACMs, however, is that as they get older they are prone to becoming friable, or able to be reduced to powder by hand pressure alone. Asbestos particles, when they are friable, are readily released into the atmosphere, where they can cause health problems after they are inhaled or ingested. Unfortunately, it was not just workers who were at risk; secondary exposure frequently happened when people carried asbestos particles home on their skin, in their hair, or on their clothing.

The Danger of Asbestos

Asbestos-related diseases, in contrast to typical job-related injuries, which are readily observed and known about immediately following the incident, may take ten, twenty, or even thirty years to appear. With such a lag time between exposure to asbestos and the onset of symptoms, a worker might not associate the current health problem with work he or she did decades ago. Especially with mesothelioma, the sooner it is diagnosed, the higher the odds of surviving or at least of improved quality of life. Therefore, if you were employed as a molder, or spent much time near someone else who was; it is important to inform your physician about the chance of exposure to asbestos. The mesothelioma survival rate is commonly thought of as grim. However, early diagnosis and consistent treatments like mesothelioma radiation can improve the prognosis for this disease.

Author: Linda Molinari

Editor in Chief, Mesothelioma Cancer Alliance

Linda Molinari

Bowker, Michael. Fatal Deception: The Untold Story of Asbestos (New York: Touchstone, 2003)

McClarin Plastics, "Cold Molding" -

University of Wisconsin - Asbestos Containing Material (ACM) - Laboratories and Shops

University of Wisconsin - Asbestos Disposal

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