sample collection
Parents were provided with a polyethylene tube and instructed to collect urine samples (first morning voids). Collected urine samples were placed in resealable plastic bags and kept in an ice box during transport. Hand wipes were collected during the home visits wherein the trained researcher wiped both sides of the participant’s hands, using gauze pads moistened with isopropanol.18 Wipe samples were immediately wrapped in aluminum foil, placed in resealable plastic bags, and labeled using identity codes, before placing them in an ice box packed with dry ice for transport. Collection of pyrethroid residues from the hand wipe samples is showed in Figure 1. Both urine and hand wipe samples were stored at −40°C until analysis.