Isocyanate SWYPETM Semi-quantitative Surface Sampling in the Puget Sound Collision Repair Industry - Pilot Study

Isocyanates are a leading cause of work-related asthma and workers in the auto-collision repair industry are at high risk for isocyanate exposures, particularly by the dermal route (Bello et al, 2007a and SHARP 2005). This project aims to extend and validate a rapid colorimetric surface wipe method, SWYPE™, for measuring isocyanate surface contamination in the workplace (Liu et al 2000 and 2005, and websites: CLI lab Inc. A semi-quantitative pilot study was conducted to evaluate the use of the SWYPE™ method in auto body shops and to examine the extent of contaminated surfaces. RGB (Red-Green-Blue) spectral analysis of the SWYPE™ was compared to standard quantitative method W4002 for validation purposes. Isocyanate SWYPE™ Semi-quantitative Surface Sampling in the Puget Sound Collision Repair Industry-Pilot Study SWYPES™ (n=122) were used for surface sampling at 20 collision repair shops in the Puget Sound region. A semi-quantitative approach was used to assess the loading of the SWYPES™ with a scale of 0 to 3, where 0 (yellow) had no contamination, and 3 (deep red) had the highest contamination (Figure 1). Semi-quantitative analysis of the field samples showed that isocyanate surface contamination in paint shops was mainly confined to the mixing room and the spray booth, with over 90% of positive samples in the paint mixing room alone (n=26). Semi-quantitative evaluation of discarded gloves showed that most (>70%) were contaminated on the outside and ~12% had detectable isocyanates inside the gloves. The semi-quantitative pilot study suggests a need for more careful examination of protective clothing and glove materials used in mixing and painting operations. Isocyanate SWYPE™ Surface Sampling Characterization and Validation SWYPE™ samples were collected in the laboratory and in the field. Samples were archived by recording images of the color change on a calibrated portable digital scanner. A digital image analysis algorithm was developed to quantify the surface loading on SWYPE™s. The amount of color change in field images was compared to a series of reference images collected with a known loading of the specific isocyanate-containing hardener. The algorithm allowed for quantification over a range of loadings from ~0.1 to 24.0 !g/cm 2 with reproducibility of >90% and an extraction efficiency of >90% (estimated by comparing direct loading on the SWYPE TM versus wiping of controlled loading on aluminum foil). The lowest visually detected SWYPE™ in the lab (6-10ug on 10x10cm surfaces) is higher than that suggested by the manufacturer (3-5!g). We acknowledge that surface …