Water Hardness, Detergent Type, and Prewash Product Use as Factors Affecting Methyl Parathion Residue Retained in Protective Apparel Fabrics

Abstract

The purpose of this study was to examine the effect of water hardness, detergent type, and prewash product on methyl parathion residue remaining in fabric after laundering. Measured water hardness had not been included as a variable in earlier studies. Its effect is particularly important as water hardness may interfere with the cleaning effectiveness of the detergent, the detersive action of an anionic product being reduced more than that of a nonionic product. The factorial design included (a) two detergents (nonionic and anionic) (b) a prewash product (laundered with or without) (c) fabric finish (unfinished or repellent finished) and (d) five levels of water hardness (0, 300, 600, 900, and 1200ppm). Unlaundered 8 X 8 cm specimens were spiked with 0.2 ml of methyl parathion. Residue was extracted following laundering and quantity remaining was determined by gas chromatography. The results showed that the repellent finish was effective in limiting methyl parathion absorption. After laundering, residues were greater for a soil-repellent finished fabric than the unfinished fabric even though the initial contamination was lower for the soil-repellent finished fabric. As level of water hardness increased, residue retained increased. The anionic phosphate detergent was less efficient in methyl parathion removal than was heavy duty liquid detergent; however, use of a prewash product before laundering with the anionic detergent resulted in residues on unfinished specimens at levels similar to those for the heavy duty liquid detergent.