Distribution of Malathion and Methyl Parathion on Cotton/Polyester Unfinished and Durable-Press Fabrics Before and After Laundering as Determined by Electron Microscopy

Abstract

The distributions of the organophosphorus pesticides malathion and methyl parathion on 50% cotton/50% polyester fabric with and without a durable-press finish were studied by electron microscopy. Osmium tetroxide was used to tag the pesticides for the study of their distribution on the yarns and fibers by backscattered electron imaging and energy-dispersive X-ray microanalysis. Distributions of malathion and methyl parathion on the unlaundered specimens were similar, with high concentrations present on the surfaces of both polyester and cotton fibers and in the cotton lumen. No pesticide was observed inside the polyester fibers. Laundering removed 60 to 70% of each pesticide by cleaning the surfaces of the fibers but had little effect on the concentration of pesticide in the cotton lumen. Laundering removed more malathion than methyl parathion from the surfaces of the polyester fibers. The durable-press finish had no effect on the total amount retained or on the distribution of malathion after laundering, while slightly more methyl parathion was observed on the unfinished fabric.