The purpose of this study was to determine whether layering fabrics which are readily available to agricultural workers would reduce penetration of methyl parathion. The fabrics used were cotton denim, cotton printcloth, cotton jersey knit, and polypropylene knit. The two chemically-different knit fabrics (cotton or polypropylene) were used to determine the effect of the second layer's chemical composition on penetration.
Penetration studies were conducted using radiolabeled pesticide. Single layers of heavyweight denim acted as a trap allowing little pesticide to pass through, while the thinner shirtweight fabric was easily penetrated. In two-layer systems that used shirtweight printcloth for the outer layer, penetration was reduced by the presence of the second fabric layer, while air permeability remained unchanged.
Cotton and polypropylene knit fabrics were used as underlayers with the cotton printcloth and were examined for differences in retention and penetration. When a hydrophilic, cotton knit underlayer was used, 55.1% of the applied methyl parathion remained in the underlayer, and just under 44% was in the printcloth. On the other hand, when a hydrophobic, polypropylene knit was used under the printcloth, 7.3% of the applied methyl parathion was retained on the polypropylene fabric, and 92.5% remained in the top layer. The collection pads underneath, designed to measure total penetration through the fabric system, contained equal amounts of pesticide. Since the polypropylene underlayer contained only one-seventh as much methyl parathion as the cotton underlayer, we assume that the polypropylene underlayer had less pesticide available for dermal absorption.