Speaking of painting...Respirator tips

[MKMSG at aol.com]

The following is an extract of an OSHA study done at a Denver automotive  
paint shop where urethane containing polyisocyanates is sprayed daily.  The  
study concluded the workers were protected at an adequate level (they wore  
protective suits and were using a forced air breathing system).  I'm not  advocating 
not using automotive polyurethanes, but if you're going to use them,  be 
aware of the dangers and take the precautions recommended by the paint  
manufacturers. I used to spray Imron with great results, but am now  experimenting with 
other paints to eliminate the hazard.
 
Mike Moritko
 
 
OSHA Report Extract:  
 
Probably the most debilitating health effects from workplace exposure to  
diisocyanates are respiratory and dermal sensitization. Exposures can lead to  
sensitization depending on the type of exposure, the exposure concentration, the 
 route of exposure, and individual susceptibility. Dermal sensitization can  
result in such symptoms as rash, itching, hives, and swelling of the  
extremities.18,21 Respiratory sensitization from exposure to  diisocyanates results in 
the typical symptoms of asthma. Estimates of the  prevalence of 
diisocyanate-induced asthma in exposed worker populations vary  considerably; from 5% to 
10% in diisocyanate production  facilities,22,23 to 25% in polyurethane 
production  plants,22,24 and 30% in polyurethane seatcover  operations.25

A worker suspected of having  diisocyanate-induced sensitization will present 
with symptoms of traditional  acute airway obstruction; e.g., coughing, 
wheezing, shortness of breath,  tightness in the chest, nocturnal awakening, 
etc.18,20 Upon first  exposure to diisocyanates, the worker may develop an asthmatic 
reaction  immediately or several hours after exposure, after the first months 
of exposure,  or after several years of exposure.18,20,23,26,27 some evidence 
 exists which suggests that the onset of sensitization occurs after a mean  
exposure interval of two years.28 After sensitization, any exposure,  even to 
concentrations below any occupational exposure limit or standard, can  produce 
an asthmatic response which may be life threatening. This asthmatic  reaction 
may occur minutes after exposure (immediate), several hours after  exposure 
(late), or a combination of both immediate and late components after  exposure 
(dual).20,26 The late asthmatic reaction is the most common  occurring in 
approximately 40% of diisocyanate-sensitized workers.29  Recurrent nocturnal asthma 
has been described in workers sensitized to TDI and  MDI.30,31 An improvement 
in symptoms may be observed during periods  away from the work environment 
(weekends,  vacations).18,20,26

The percentage of sensitized workers with  persistent symptoms of asthma 
after years of no exposure may be 50% or higher.  Studies have shown that workers 
with persistent asthma have a significantly  longer duration of symptoms prior 
to diagnosis, larger decrements in pulmonary  function, and a severe degree 
of nonspecific bronchial hyperactivity at  diagnosis.26 These data suggest that 
prognosis is improved with early  diagnosis of diisocyanate-induced 
respiratory sensitization and early removal  from diisocyanate exposure. This 
emphasizes the need to minimize workplace  exposure concentrations, and for active 
medical surveillance of all workers  potentially exposed to diisocyanates.

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