Use of Methylene Blue Dye to Predict Fabric Penetration by Malathion

This study developed and verified a test method for the screening and selection of fabric finishes proposed for use in protective garments for agricultural workers exposed to pesticide sprays. Six nonwoven and four woven fabrics with and without barrier finishes were tested for aerosol spray penetration using 0.1% methylene blue dye as an indicator of pesticide penetration with three spray emulsions: (1) water; (2) water/surfactant (48:1); and (3) unrefined cottonseed oil/surfactant (4:1). The procedure was repeated using the following pesticide emulsions: (1) water/malathion (100:4) and (2) unrefined cottonseed oil/malathion (100:8).

Analysis of variance was used to compare the results of the water/malathion and the results of the cottonseed oil/malathion spray tests between categories of dye penetration. In each case, there was significant difference between group variation. Duncan's Multiple Range Test (p < 0.05) indicated that fabrics that did not allow penetration by the methylene blue dye had significantly lower levels of malathion present in the extracts. The spray tests indicated that aerosol spray penetration was reduced by the presence of fluorocarbon barrier finishes on the fabrics.