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Background Polyurethanes are a class of isocyanate-based organic coatings commonly used to control corrosion on high-value metallic structures. Despite their widespread use, dermal exposure to these isocyanate-containing coatings presents a significant occupational health risk to workers, including the development of allergic and irritant contact dermatitis and systemic sensitization. At present, little is known about the effectiveness of the protective garments commonly used to prevent dermal exposure to polyurethane coatings in construction trades. Objectives The primary objective of this study was to measure the permeation and penetration of isocyanates from polyurethane anticorrosion coatings though a selection of protective garments. In addition, a standardized spray procedure using a fixed-position spraying technique was evaluated as an option to minimize variability in coating application. Methods Five disposable garment materials were evaluated for resistance to isocyanates during this study: latex gloves (0.076 mm), nitrile gloves (0.078 mm), Tyvek coveralls (0.105 mm), polypropylene/polyethylene (PP/PE) coveralls (0.116 mm), and a cotton t-shirt (0.382 mm). A permeation test cell system was used to evaluate each garment material against two products: a polyurethane zinc-rich primer based on 4,4′-methylene diphenyl diisocyanate and an aliphatic finish coating based on prepolymers of 1,6-hexamethylene diisocyanate. Glass fiber filters pretreated with 1-(9-anthracenylmethyl)piperazine were used to collect penetrating isocyanates during the 120-min test period, which were analyzed by liquid chromatography–tandem mass spectrometry. Polytetrafluoroethylene loading filters were sprayed in series with permeation test cells and analyzed gravimetrically to assess the homogeneity of coating application. Results The latex gloves demonstrated the highest rate of isocyanate permeation of all evaluated garments during testing with both coatings (primer: 27.38 ng cm−2 min−1; finish coating: 7.39 ng cm−2 min−1). Nitrile gloves were much more resistant than latex gloves (primer: 1.89 ng cm−2 min−1; finish coating: 1.26 ng cm−2 min−1) and were not permeated by the finish coating until after 15 min. The PP/PE coverall provided the most consistent resistance to both coatings (primer: 0.08 ng cm−2 min−1; finish coating: 1.27 ng cm−2 min−1), whereas the Tyvek coverall was readily permeated by the primer (primer: 3.47 ng cm−2 min−1; finish coating: 0.87 ng cm−2 min−1). The cotton t-shirt was rapidly permeated by the primer during the first 5 min of exposure (primer: 146.65 ng cm−2 min−1; finish coating: 4.64 ng cm−2 min−1). In addition, the fixed-position spraying technique used during this study demonstrated a significant reduction in loading variability within each batch of test cells when compared to manual spray application. Conclusion Nitrile gloves demonstrated superior resistance to both isocyanate-containing coatings in comparison to latex gloves. Although both coverall materials were resistant to permeating isocyanate within the established thresholds, the PP/PE coverall provided more consistent resistance to both coatings. Owing to the cotton t-shirt's high rate of penetration with both coatings, it is recommended only as a secondary barrier. Study results showed that the use of fixed-position spray techniques provided consistent and reproducible results within each batch of test cells. Additional test design modifications are necessary to further reduce variability between batches and ensure more consistent coating thickness. [ABSTRACT FROM AUTHOR]

Background Diisocyanates (isocyanates), including methylene diphenyl diisocyanate (MDI), are the primary reactive components of spray polyurethane foam (SPF) insulation. They are potent immune sensitizers and a leading cause of occupational asthma. Skin exposure to isocyanates may lead to both irritant and allergic contact dermatitis and possibly contribute to systemic sensitization. More than sufficient evidence exists to justify the use of protective garments to minimize skin contact with aerosolized and raw isocyanate containing materials during SPF applications. Studies evaluating the permeation of protective garments following exposure to SPF insulation do not currently exist. Objectives To conduct permeation testing under controlled conditions to assess the effectiveness of common protective gloves and coveralls during SPF applications using realistic SPF product formulations. Methods Five common disposable garment materials [disposable latex gloves (0.07 mm thickness), nitrile gloves (0.07 mm), vinyl gloves (0.07 mm), polypropylene coveralls (0.13 mm) and Tyvek coveralls (0.13 mm)] were selected for testing. These materials were cut into small pieces and assembled into a permeation test cell system and coated with a two-part slow-rise spray polyurethane foam insulation. Glass fiber filters (GFF) pretreated with 1-(9-anthracenylmethyl)piperazine) (MAP) were used underneath the garment to collect permeating isocyanates. GFF filters were collected at predetermined test intervals between 0.75 and 20.00 min and subsequently analyzed using liquid chromatography-tandem mass spectrometry. For each garment material, we assessed (i) the cumulative concentration of total isocyanate, including phenyl isocyanate and three MDI isomers, that effectively permeated the material over the test time; (ii) estimated breakthrough detection time, average permeation rate, and standardized breakthrough time; from which (iii) recommendations were developed for the use of similar protective garments following contamination by two-component spray polyurethane foam systems and the limitations of such protective garments were identified. Results Each type of protective garment material demonstrated an average permeation rate well below the ASTM method F-739 standardized breakthrough rate threshold of 100.0 ng/cm2 min−1. Disposable latex gloves displayed the greatest total isocyanate permeation rate (4.11 ng/cm2 min−1), followed by the vinyl and nitrile gloves, respectively. The Tyvek coverall demonstrated a greater average rate of isocyanate permeation than the polypropylene coveralls. Typical isocyanate loading was in the range of 900 to 15,000 ng MDI/cm2. Conclusion Permeation test data collected during this study indicated that each type of protective garment evaluated, provided a considerable level of protection (i.e. 10–110-fold reduction from the level of direct exposure) against the isocyanate component of the SPF insulation mixture. Nitrile gloves and polypropylene coveralls demonstrated the lowest rate of permeation and the lowest cumulative permeation of total isocyanate for each garment type. [ABSTRACT FROM AUTHOR]