27 Biosafety Manual Using work practices that block routes of exposure can prevent workplace infection. Good microbiological techniques must always be used in the laboratory: • Wearing appropriate PPE blocks potential routes of exposure. • Eating, drinking, smoking, chewing tobacco, applying cosmetics, or storing food in laboratories is strictly prohibited. Potentially contaminated hands must be kept away from the mouth, eyes, and non-intact skin. • Hands must be washed frequently, even after wearing gloves, and scrubbed vigorously with soap and water for a full 30 seconds (as long as it takes to sing “Happy Birthday” or the “Iowa State Fight Song”). The physical removal of organisms from the skin is just as important as using a disinfectant. • Work surfaces and equipment must be decontaminated after using biohazardous materials. The following are suggestions for common laboratory procedures to follow when conducting work with biohazardous materials. Each will help prevent biohazardous materials from entering the body through common exposure routes. Pipetting Pipetting can cause the creation of aerosols and splashing. Micropipettors may also create aerosols. • Mouth pipetting is prohibited. Mechanical pipetting aids must be used. • All biohazardous materials must be pipetted in a biosafety cabinet if possible. • Cotton-plugged pipettes should be used. Cotton-plugged micropipette tips are also available. • Biohazardous materials must never be forcibly discharged from pipettes. “To deliver” (TD) pipettes must be used instead of pipettes requiring blowout. • To avoid splashing, biohazardous material should be dispensed from a pipette or micropipettor by allowing it to run down the receiving container wall. • After use, pipettes should be placed horizontally in a pan filled with enough liquid disinfectant to completely cover them. Allow adequate disinfection time before disposal of pipettes. • Plastic micropipette tips and pipettes are sharp and should be disposed of in a puncture-resistant container after decontamination.