Multiple washings are necessary if pesticide used is highly toxic or concentrated. In fact, discard clothing completely saturated with most concentrated, highly toxic pesticides. Use disposal directions on the side of the pesticide container label. Clothing contaminated with moderate or low-toxicity pesticides do not warrant such drastic measures. Launder clothing after each day's use to maximize removal of chemicals.
Accumulated residues are harder to remove.
And, wearing clothing that already contains a pesticide puts the wearer at additional risk. Use a disposable plastic bag placed in a cardboard box to hold them rather than a cloth bag or laundry basket. Wear rubber gloves when putting contaminated garments into the bag, and again when placing garments in the washer. If pesticide has left a stain, apply a prewash soil and stain remover or rub in a heavy duty liquid detergent. Pre-rinse contaminated clothing by hosing down outdoors, soaking in a separate tub or pail, or agitating in the washing machine.