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Occupational Health branch

Occupational Health Watch: May 2022

May is Asthma Awareness Month: Spotlight on Diisocyanates and Work-Related Asthma

The chemical group called diisocyanates has been known as a cause of work-related asthma (WRA) since the 1950s. However, workers using these chemicals continue to get this serious and debilitating lung disease. A recent case report was published about a foundry worker who died due to WRA caused by methylene diphenyl diisocyanate (MDI). The worker was using MDI to bind the sand for the molds used in metal casting. MDI and other chemicals are used in many processes and products, including spray foam insulation, adhesives, spray-on truck bed liners, wind turbine blades, and auto paint.

Text: May is asthma awareness month. Take action to help america breathe easier. In California the Work-Related Asthma Prevention Program has tracked nearly 70 cases of WRA associated with these chemicals. The jobs are varied and include auto and aircraft painters, chemical technicians, health care workers, foam manufacturing workers, snowboard makers, carpenters, and sculpture makers.

Once a person is sensitized to a chemical (i.e., develops allergic-type asthma), extremely low levels can trigger an asthmatic response. Cal/OSHA permissible exposure limits are generally higher than these levels and cannot be relied upon to protect workers against WRA. Additionally, both respiratory and skin exposures have been shown to lead to WRA. 

WRA can be prevented by:

  • Switching to safer chemicals or processes where possible
  • Using engineering controls such as local exhaust ventilation and enclosures
  • Implementing medical surveillance
  • Training workers about chemical hazards
  • Using personal protective equipment such as respirators and chemical resistant gloves

To prevent WRA it is important to promote the implementation of exposure prevention methods in workplaces for all uses of chemicals, in industries both old and new. 


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