Written and maintained by CASRAI Editorial Board
Last updated
This page describes products and general use; it is not medical advice.
Pipetting by mouth is prohibited. Mouth pipetting means drawing liquid into a pipette by sucking on its upper end. It is a historical practice that safety rules now forbid, and it has been replaced by mechanical pipetting aids. This page explains what the rules actually say, how far each one reaches, and where to read more. It deliberately gives no instructions for doing it.
What mouth pipetting is
A pipette is a tube used to measure and transfer small volumes of liquid. Mouth pipetting meant using the operator’s own suction to fill it. Because the operator’s mouth sits at the open end of a tube that has just been in contact with the sample, the practice puts the operator’s mouth in the same pathway as the liquid being handled. Ingestion is one of the recognised routes of laboratory-acquired infection, and mouth pipetting is its historical example (see biosafety levels BSL-1 to BSL-4).
What the rules say
Two U.S. OSHA texts address it, and they differ in scope and in legal force.
| Source | Wording | Scope | Status |
|---|---|---|---|
| OSHA 29 CFR 1910.1030(d)(2)(xii), Bloodborne Pathogens standard | “Mouth pipetting/suctioning of blood or other potentially infectious materials is prohibited.” | Blood and other potentially infectious materials | Regulation (binding where the standard applies) |
| OSHA 29 CFR 1910.1450, Appendix A (laboratory standard) | “Pipetting should never be done by mouth.” | General rule for laboratory work with chemicals | Non-mandatory recommendations |
In other words, the bloodborne pathogens standard is a prohibition with a defined scope, while the laboratory standard’s appendix is guidance that applies the same principle to chemical work. BSL-2 practices also include no mouth pipetting among their sharps precautions; see the BSL guide and the ABSL-2 requirements guide.
What replaces it
Laboratory rules call for mechanical pipetting aids instead, such as the pipette fillers, bulbs and pipettors that attach to a pipette and create the suction mechanically. CASRAI’s lab safety rules guide states the working rule as “Never mouth-pipette. Use mechanical pipetting aids exclusively.” For the adjustable, piston-driven instruments used for small volumes, see what a micropipette is.
Who uses these: laboratory staff, technicians and students in teaching and research laboratories, and clinical laboratory personnel handling patient specimens.
Common mistakes
- Treating the guidance as optional because Appendix A is non-mandatory. It is a recommendation in that document, but it states the rule without exception: pipetting should never be done by mouth.
- Assuming the prohibition only applies to hazardous samples. The bloodborne standard is scoped to blood and other potentially infectious materials, while the laboratory guidance covers chemical work generally.
- Leaving the rule out of written procedures. A rule that is not written down is easy to miss, so it belongs in lab SOPs and onboarding. See biological risk assessment and laboratory protocols.
FAQ
Is mouth pipetting still allowed?
No. OSHA’s bloodborne pathogens standard prohibits it for blood and other potentially infectious materials, and OSHA’s laboratory-standard guidance says pipetting should never be done by mouth.
What is a pipette filler?
A pipette filler is a mechanical aid that fits onto a pipette and draws liquid in without the operator’s mouth, which is the category of device laboratory rules require in place of mouth pipetting.
Is OSHA’s Appendix A a legal requirement?
No. The appendix is non-mandatory. The binding text is the bloodborne pathogens provision at 1910.1030(d)(2)(xii), within its scope.
Sources
- OSHA, 29 CFR 1910.1030, Bloodborne pathogens, paragraph (d)(2)(xii): https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1030. Checked 2026-10-29.
- OSHA, 29 CFR 1910.1450 Appendix A, National Research Council recommendations concerning chemical hygiene in laboratories (non-mandatory): https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1450AppA. Checked 2026-10-29.
