Isocyanate exposure potential in construction industry polyurethane products use

Isocyanates are reactive chemicals that are used in the production of polyurethane adhesives, coatings, and foams. Respiratory and dermal exposure to isocyanates can cause a number of adverse health effects, including irritation, sensitization, and isocyanate asthma. Spray polyurethane foam insulation is an increasingly popular construction product, though the level of exposure to isocyanates during the foam application and curing process is relatively unknown. In this study, we applied foam insulation products marketed towards both industry and the home user. We used qualitative and quantitative SWYPE(TM) wipes to sample the surface of the foam for isocyanates at time increments post-application. Additionally, we took biopsies of the finished foam material to determine the internal quantity of isocyanate present. Results suggest that all polyurethane foam products tested show statistically similar rates of decay of NCO of MDI on the surface of the material over time following application (range 0.005 to 4.034 micrograms NCO of MDI). Industrial products tested demonstrated the highest initial levels of MDI post-application, though industrial products were not significantly different from at-home products in terms of decay curve. Matched qualitative and quantitative SWYPE(TM) samples indicate a qualitative predictive threshold of 0.4 micrograms NCO of MDI, though a graded colorimetric response associated with quantitative isocyanate level was not observed. Mean quantity of MDI and pMDI in core biopsies was 0.955 micrograms NCO and 3.575 micrograms NCO, respectively. Core biopsies suggest that higher levels of MDI may exist in internal material, despite apparent curing on the surface of the foam. These results suggest the need for increased precaution against exposure during and after the application process.