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Cashins & Associates Blog

Industrial Hygiene Review: Isocyanates

Posted by Eileen Watkins on Thu, Jul, 23, 2015 @ 17:07 PM


Isocyanates compounds have qualities that make them attractive candidates for several different applications.  Unfortunately their toxic properties can seriously harm exposed individuals.  In fact, isocyanates can cause irreversible health effects that can impair workers to the point that they are unable to keep their jobs.  Read on to learn more.

Organic compounds that contain the functional group N=C=O belong to the isocyanate family.  Isocyanates can be divided into 2 subgroups:  diisocyanates have 2 N=C=O groups whereas polyisocyanates have more than 2 functional groups.  Isocyanates have long chemical names and are almost always referred to by their abbreviations.  MDI, TDI, and HDI are the most common diisocyanates.  HDI biuret and HDI isocyanurate are popular polyisocyanates.  The chemical names for these compounds are listed at the end of this article.

Isocyanates have relatively low molecular weights and are highly reactive.  These properties explain their wide use in both commercial and consumer products.  Specifically, isocyanates are used to manufacture polyurethanes, compounds which are found in a wide variety of products including paints & varnishes, flexible & rigid foams, composite wood, medical devices & supplies, and even clothing (spandex fibers). 

As you might imagine, compounds that are highly reactive in a test tube or reaction vessel are almost always highly reactive in the human body.  This is true in the case of isocyanates.  For starters, they are strong irritants to the skin, eyes, and respiratory tract.  In addition, isocyanates are skin and respiratory allergens.  This means that skin contact with isocyanates increases the risk of an allergic skin reaction called allergic contact dermatitis.  Similarly, respiratory exposures to isocyanates increase the risk of an allergic respiratory reaction that we commonly refer to as asthma.

Let's review a few key points about allergens in order to gain a deeper appreciation of how menacing they can be.  Allergens are substances that are made by food (peanuts, eggs, gluten), plants (pollen, poison ivy), animals (bee stings, animal dander), or chemicals (isocyanates, formaldehyde, nickel).  They are also referred to as sensitizers.  As you know, allergens don't cause allergic reactions in all individuals.  For example, only a subset of the population is allergic to peanuts.  The same is true for isocyanate allergies.  Unfortunately we are not able to predict who is allergic - or who will become allergic - to isocyanates.  This means that all workers need equal protection against these compounds.

It's important to highlight that the immune system's first encounter with an allergen does NOT cause an allergic reaction.  In fact, several exposures may be needed before someone experiences an allergic reaction.  This means that isocyanate workers could be exposed to these chemicals for many days, months, or years before they develop an allergy.  This latency period of can be misleading and give your workers - or you - a false sense of security.  This is another reason why it is critical to protect all workers all the time from isocyanates.

Allergic reactions can be very debilitating, especially considering that subsequent reactions tend to increase in intensity.   Allergic contact dermatitis causes inflamed, red, and extremely itchy skin.  Asthma causes wheezing, shortness of breath, and chest tightness.  It's important to note that allergic individuals are not able to tolerate contact with even low concentrations of allergens.  These factors mean that it is nearly impossible to keep workers with isocyanate allergies on the job.  Rather, they will need to be reassigned to another position or may have to leave work permanently due to this disability.  These outcomes effect not only your workers, but your bottom line.

Do you have isocyanates in your workplace? Are your workers adequately protected?  Have they been trained to understand the hazards associated with isocyanates?  Cashins can perform an industrial hygiene assessment to evaluate your workplace for isocyanate hazards and help you implement practical solutions that protect your workers and you.  Click on the button at your right to submit your request for an EHS assessment! 

MDI:  Methylene diphenyl diisocyanate

TDI:  Toluene diisocyanate

HDI:  Hexamethylene diisocyanate



Topics: industrial hygiene

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