SEDL / STP / STP1133-EB / STP19207S

The Use of Bleach Pre-Treatments in Chlorpyrifos Residue Removal from Cotton Workwear

Perkins, HM
Research AssociatesProfessor, University of Alberta, Edmonton, AB

Rigakis, KB
Research AssociatesProfessor, University of Alberta, Edmonton, AB

Crown, EM
Research AssociatesProfessor, University of Alberta, Edmonton, AB

Pages: 12    Published: Jan 1992

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Abstract

The effectiveness of chlorine and oxygen bleach soak pre-treatments in removal of chlorpyrifos from cotton was examined. A 0.5 mL aliquot of chlorpyrifos (1.0% a.i., emulsifiable concentrate) was pipetted onto fabric specimens cut from 100% cotton. Laundering treatments included: no pre-treatment/one and two washes; Spray ‘n Wash^® pre-treatment/one and two washes; oxygen bleach soak/1 wash; and chlorine bleach soak/one wash. Analysis of variance indicated significant differences (p < 0.001) in percent residue remaining among laundry treatments. The most effective laundry protocol included a 0.4% chlorine bleach 3-hour soak at 50°C (0.03% residue remaining), followed by the 2.5% oxygen bleach 12-hour soak at 50°C (3.3% residue remaining). The least effective was a single wash with no pre-treatment (44.7% residue remaining). Specimens subjected to 0, 5, 10 and 25 chlorine bleach soak/washes became progressively weaker, but users may accept workwear with lower durability in exchange for low residues of chlorpyrifos when the chlorine bleach pre-treatment is used.