Thermoset Plastic Manufacturing and PAH Exposure

Upon entering the kitchen and flicking on the light, little thought is likely given to where or how that light switch was made, any more than thought is given to the countertops on which the food is prepared or the pot handles of the vessel used to cook the food. Those who work in the thermosetting plastics industry, however, think about these products all the time. It’s what they do.

Plastics are one of the most used and indispensable materials in modern life and thermoset plastics, in particular, are valued for their stain and heat resistance and for their durability.

Employing over 1.1 million workers in the United States, the plastics industry represents a substantial percentage of the American workforce. (1) Of those workers, many of them work in thermosetting, jobs ranging from raw material manufacturing to plastics processing.

Thermoset plastics are synthetic materials that cannot be molded or reheated after their initial heat formation. Thermosetting is the process of transforming granular material into molded shapes, curing through a chemical reaction activated by heat and pressure, which in turn forms a strong molecular bond. This is in contrast to thermoplastics, which are products that soften when heated and harden after cooling.

As with all industries that manufacture goods, there are occupational risks.

One such risk is PAH exposure. PAHs, polycyclic aromatic hydrocarbons, are a group of chemical compounds that are found naturally in the burning of fossil fuels and are by-products of heat-produced manufactured goods such as medicines, dyes and plastics. Of these compounds, naphthalene is a top contender of risk: a substance that is not only pervasive, but also harmful. (2)

The chemical naphthalene is most commonly known for its use in mothballs. Naphthalene evaporates easily and gives mothballs their distinct odor. But in the production of thermosets, naphthalene is released into the air at the melting and burning stage, causing vapors to enter a worker’s air space. Once airborne, naphthalene is broken down by moisture and sunlight but not quickly; often lingering in the atmosphere up to 24 hours. (3)

Acute (short-term) symptoms of naphthalene exposure will present immediately when levels are high. Various symptoms include headache, confusion, nausea, vomiting, abdominal pain, dermatitis, optical twitching and corneal damage. Organs targeted are the eyes, skin, blood, liver, kidneys, and central nervous system. (4) Cataracts have also been reported in workers acutely exposed to naphthalene by inhalation. Chronic (long-term) exposure, especially at low levels, is harder to identify due to symptoms being typical of a variety of other causations. Chronic symptoms are similar to those of acute exposure, with additional indicators such as retinal damage and cataracts. The EPA has classified naphthalene as a possible (Group C) human carcinogen. (5)

But naphthalene exposure to workers in the thermosetting industry is by no means inevitable. Preventative measures on the manufacturing floor – protective clothing, proper ventilation, and indoor air cleaning products – can eliminate the presence of offending vapors and fumes.

At Air Systems Inc, we protect our customers in the plastics industry by providing them with stellar indoor air cleaning equipment and products. Contact us today to set up a free consultation with one of our clean air specialists.