Mist particle diameters are related to the toxicity of waterproofing sprays: comparison between toxic and non-toxic products.

Although respiratory failures following exposure to waterproofing sprays have been reported worldwide, their mechanism remains unknown. In this study, we sorted each of 12 commercial waterproofing sprays into either the Toxic Group (No 1-4) or the Non-Toxic Group (No 5-12) and compared the pathological changes produced in the lungs of mice after their inhalation. Then we determined the diameters of each product's mist particles and their adhesion rates to cloth. The 4 products in the Toxic Group, reported as toxic to human beings, caused severe damage to mice lungs, whereas the 8 products in the Non-Toxic Group, not reported as toxic, caused little if any damage. The percentage of particle < or = 10 microns were significantly higher in the Toxic Group than in the Non-Toxic Group. The adhesion rate to cloth correlated to the mean particle diameter and was significantly lower in the Toxic Group than in the Non-Toxic Group. The toxic sprays generated mists of smaller particle diameter than the non-toxic sprays, suggesting that the mist particle diameters of waterproofing sprays are related to their toxicity.