Why should you never pipette by mouth?

Never pipetting by mouth is critical primarily because it can lead to accidental ingestion of chemicals. Many substances used in a laboratory setting can be hazardous, including toxic, corrosive, or carcinogenic materials. By using a mouth pipetting method, there is an inherent risk of drawing harmful liquids into the mouth, which poses serious health risks. In contrast, appropriate pipetting techniques involve mechanical aids that ensure safety and accuracy while eliminating the risk of direct human exposure to dangerous substances.

Other options may touch on practical aspects of pipetting, such as speed or accuracy, but they do not take into account the fundamental safety concerns associated with the practice. Lab safety protocols emphasize the use of proper tools like pipette bulbs or electronic pipettors to minimize risk, make processes safer, and promote better laboratory practices. Thus, the focus on avoiding mouth pipetting is grounded in ensuring the health and safety of those working in the lab environment.