Suck It: The Ins and Outs of Mouth Pipetting


If you ever find yourself working in an infectious disease laboratory, whether it’s of the diagnostic or research variety, the overarching goal is not to put any microbes in your eye, an open wound or your mouth. Easy enough, right? Wear gloves, maybe goggles, work in fume hoods and don’t mouth pipette. When working with pathogenic bacteria and viruses, priority number one is Do Not Self-Inoculate.

This is obvious for anyone who has worked in a shiny biology or chemistry lab or seen an episode of CSI: Crime Scene Investigation (we’re all friends here, just admit it), but one of the most commonly used pieces of equipment in labs prior to the 1970s was the leading cause of laboratory-derived infections: the honorable pipette. How could that be possible, you ask? By using one’s oral cavity with the pipette to measure and transfer liquids.

Today our manual pipettes are rather sophisticated, plastic-y devices perfectly calibrated for moving precisely exact milliliters, microliters and picoliters of valuable solution from one vessel to another, whether it’s of a urine sample, some spare radioactive material you have lying about or toxic solvents. But before the development of cheap mechanical pipettes in the ’70s, using your mouth to pipette solutions was more than a common sight, it was a way of the lab.

Former Centers for Disease Control (CDC) parasitologist, Dr. Mae Melvin (Lt), examines a collection of test tubes while her laboratory assistant mouth pipettes a culture to be added to these test tubes. Source: David Senser/CDC.

Don’t worry, reader, I heard you tentatively whisper, “just what exactly is mouth pipetting, dare I ask?”

Like so: insert an open-ended glass capillary tube into your mouth. Place the opposite, tapered end of the tube into a solution of your choice. Microbial stews, blood, cell culture, it is totally your call. With a method that carefully mimics the sucking of a straw, draw a solution upwards through your man-made pipette to your desired volume using the tension created by the reduced air pressure – yes, suction! Maintain the tension with your mouth. Do not suck too hard and inadvertently slurp the solution into your mouth. Careful now. Gently move the pipette end from one vessel and release your precious cargo into yet another vessel.

That is mouth pipetting.

A wonderful demonstration of mouth pipetting by Dr. Armand Frappier, a microbiologist and expert on tuberculosis. Look closely: you can see him draw a dark liquid slowly towards his mouth. What could it be? Soda, a culture of TB, serum for cell cultures? You can watch the entire video clip that this GIF is based upon here. Source: Musée Armand Frapper.

The sparsity of history on pipetting techniques (itself a shocking shortcoming, I’m sure you’ll agree), forbids us from generalizing the prevalence of this phenomena. But we do know that it was the source of a ridiculous number of accidents, whether swallowing a corrosive or toxic substance or an infection with one’s research material  (1). A survey of 57 labs in 1915 found that 47 infections  were associated with workplace practices and more than 40% of those were attributed to the practice of mouth pipetting. A longitudinal study of 921 workplace laboratory infections from 1893 and 1950 found that 17% were due to “oral aspiration through pipettes or to splashes of culture fluids into the mouth (2).”

Infection through the use of one’s oral cavity was such an occupational hazard that it warranted an article, “The Hazards of Mouth Pipetting,” from two gentleman working for the U.S. Army Biological Laboratories. In 1966 they wrote,

although the use of pipettes in the early chemistry laboratories undoubtedly led to accidental aspiration of undesirable toxic and poisonous substances, the first recorded laboratory infection due to mouth pipetting occurred in 1893 … [with] the case of a physician who accidentally sucked a culture of typhoid bacilli into his mouth …

compared with the equipment and procedures required to avoid other types of microbiological laboratory hazards, the method of avoiding pipetting hazards is so elementary, so simple, and so well-recognized that it seems redundant to mention it [emphasis added by author]. However, continued accidents and infections in laboratories illustrate, even today, that there is a lack of acceptance of the simple precautionary measured needed (2).

By the 1970s, mouth pipetting had fallen out of favor as swanky, mechanically adjustable and cheap pipettes flooded the market (3). They were not only infinitely safer but also far more accurate. Instead of drawing a semi-approximate volume of solution with the imperfect measuring device that is your mouth, standardized and calibrated pipettes were available that could zip up a solution to one’s desired volume. More precision. Better experimental results. Less contamination. More ergonomic. Fewer infections. Nowadays, mouth pipetting is explicitly banned from laboratories.

A woman mouth pipetting to select specimens of ectoparasites. Source: National Library of Medicine

And, indeed, you might think that this old school technique is thankfully old news and good for a giggle but mouth pipetting is still practiced in some countries. A study looking at the lab practices and biosafety measures of Pakistani lab technicians found that mouth pipetting was reported by 28.3% technicians (4). This paper was published just last year, in August of 2012. Another study in 2008 found that Nigerian technicians working in clinical laboratories were not only improperly vaccinated against many of the preventable diseases that they were testing for (!) as well as eating and drinking in the lab but 1 in 10 also reported mouth pipetting (5).

Lest you think this is just happening in developing countries, be rest assured that American teenagers and young adults will always find a creative way to  jeopardize their health. In 1998, a 19-year-old nursing student in Pennsylvania was  hospitalized for several days following infection with a unique strain of Salmonella paratyphi she was working with in a lab; the case report strongly suggests that mouth pipetting was the culprit behind this particular microbial misadventure (6).

Another article from 1995 assessing lab accidents found that 13% of laboratory-acquired infections were a result of mouth pipetting. That’s 92 accidents attributed to someone in a lab deliberately putting a pipette or capillary tube into their mouth and sucking up some solution laden with microbes (7). Clearly, we still have a way to go in dissuading people to stop using pipettes as straws.

A techician mouth-pipetitng environmental water samples in Malta. Image: E Mandelmann. Source: History of Medicine

A technician mouth pipetting environmental water samples in Malta. Image: E Mandelmann. Source: History of Medicine

Mechanical manual pipettes have been a godsend to technology and the sciences, saving researchers time and resources in measuring and transferring liquids. Pipettes now serve as an icon of the scientific pursuit of knowledge – we’re all familiar with the close up of the gloved hand and pipette tip hovering over some glowing liquid. It’s banal, efficient and ubiquitous. It’s the dogged, unsung hero of the lab but there were several decades when our method of pipetting was also a microbial misadventure in the waiting.


“There are reports of laboratory infections by means of the pipette with quite a variety of microorganisms. In the intestinal group: typhoid, Shigella, salmonella, cholera; among others, anthrax, brucella, diphtheria, hemophilus iniluenzae, leptothrix, meningococcus, Streptococcus, syphilis, tularemia; among viruses, mumps, Coxsackie virus, viral hepatitis, Venezuelan equine encephalitis, chikungunya, and scrub typhus.” Download this neat article on the history and epidemiology of lab-acquired infections here.

Want to see more pictures of mouth pipetting? Of course you do! I’ve been collecting them on the Body Horrors tumblr here, here, here, here and here. Here’s a sign. And here’s a riff on a meme.


1) AG Wedum. (1997) History and epidemiology of laboratory-acquired infections. J Am Bio Safety Assc. 2(1): 12-29

2) Phillips GB &Bailey SP (1966) Hazards of mouth pipetting. Am J Med Technol. 32(2): 127-9

3) JA Martin (April 13, 2001) The Art of the Pipette BiomedNet Magazine100

4) S Nasim et al (2012) Biosafety perspective of clinical laboratory workers: a profile of Pakistan. J Infect Dev Ctries. 6(8): 611-9

5) FO Omokhodion (1998) Health and safety in clinical laboratory practice in Ibadan, Nigeria. Afr J Med Med Sci. 27(3-4): 201-4

6)B Boyer et al (1998) The microbiology “unknown” misadventure. Am J Infect Control. 26(3):355-8

7) DL Sewel (1995) Laboratory-Associated Infections and Biosafety. Clin Micro Rev. 8(3): 389-405
HILL, N. (1999). Laboratory-acquired Infections: History, Incidence, Causes and Preventions, 4th edition. Eds. C. H. Collins and D. A. Kennedy. Butterworth Heinemann, Oxford 1999. Pp. 324. ISBN 0 7506 4023 5. Epidemiology and Infection, 123 (1), 181-181 DOI: 10.1017/S0950268899002514

Adventures in Dentures: The Street Dentists, Barbers & Tattoo Artists of India


My father-in-law David is a dentist and he recently emailed me an astonishing, must-watch video, “The Dentist of Jaipur.” A short documentary by Falk Peplinski that made the rounds of film festivals in 2006 and 2007, the four-minute film shows two men in this famed city in Rajasthan, India practicing dentistry on the streets.

The short, jaunty film begins with the opening of a rusty toolbox containing a stained and well-used toothbrush, tweezers and assorted metal implements. Ungloved hands unload and carefully lay out tools trade on a red blanket – medicinal bottles, dentures, mouth mirrors, pliers, a spoon. One man deftly pulls the cap off of a syringe, and rubs his fingers down the needle. Those cursed, fat flies that are omnipresent in India flit through the video resting on dentures and dental molds.

A street dentist in Bangalore with sets of individual teeth and dentures in 2006. Image: Matthew Logelin, Creative Commons. You can see more of Mr. Logelin’s work at his Flickr account here.

Pushkar and Pyara Singh, otherwise known as Doc-Junior and Doc-Senior, practice their trade on a sidewalk near a pretty fuchsia bougainvillea bush outside an unidentified train station, close to a stash of rickshaws awaiting customers disgorged from the busy station. Pyara Singh earnestly tells the camera, “The only difference between the rich doctors and us is that they have fancy chairs, fan, servants, x-ray and other gadgets. They take a lot of money. Normal people can’t afford that.” 

In the film, the duo mix methyl methcrylate paste, repair and install dentures, file teeth, inject who-knows-what substances and “practice dentistry” to their best ability without gloves, face masks, autoclaves to sterilize equipment and tools, or any proper sterile technique or infection control practices out on the open street. In one viscerally tough scene, the men inject a watery rose-colored liquid into a middle-aged woman’s mouth then use pliers to wrench a tooth that’s promptly discarded for the flies on the sidewalk. The scene made me squeal in terror so, for the faint of heart, know that the scene starts at 2:52 and lasts until 3:12.

For those that aren’t familiar with the kaleidoscopic charms of India, one of the most fascinating aspects of the country is its massive street economy. You can find anything you want on the sidewalks of this country, whether it’s fried delicacies, tattoos, freshly pressed fruit juices, sex or bus tickets, you just need to know where to look. I lived in India for nine sublime months in 2007 and 2008, mainly in Mumbai and Kolkata with extensive traveling in between. I saw an enormous amount of this massive country – Rajasthan, Maharashtra, Goa, Karnataka, Kerala, Tamil Nadu, West Bengal, Uttar Pradesh – traveling alone on trains and buses and rickshaws and I fell deeply in love. I definitely partook in the street economy – fried food, hot chai, juice. If you can name it, I probably ate it on a street in India. Though I never saw any instances of street dentistry, barbers shaving patient men on sidewalks were a commonplace sight throughout the many cities and towns I traveled through. And many of the friends I made on my travels received haircuts and shaves from these street barbers.

In one of my more vivid memories, I saw a young man in Kolkata that was setting up a blanket and carefully laying out tools in preparation for tattooing any willing pedestrians. I remember being absolutely gobsmacked as this man noticed me stalling pedestrian traffic on the sidewalk, my jaw gaping and eyes wonderstruck, and he eagerly beckoned me to get a quick tattoo under the underpass of a bustling intersection where many buses dropped off passengers. For months I had seen hundreds of Indians sporting black and fuzzy tattoos on their inner forearms and hands, typically of the om or aum symbol that is ubiquitous in the country. This sacred syllable was spray-painted on walls, incorporated into restaurant names, depicted as glittery stickers sported on buses and trucks and sported proudly on many Hindus as a poorly drawn tattoo. You may have noticed in the “Dentist of Jaipur” that the Singh duo both sported fuzzy tattoos on their hands.

A roadside barber shaving a customer in Varanasi. Image: R Barraez D´Lucca, Creative Commons. Click to see more of D’Lucca’s work.

These types of intimate professions – dentists, barbers and tattoo artists – that practice on the streets and sidewalks of India can play a vital role in the transmission of infections in their clientele. Unsafe, communal practices with razor blades, syringes and any tools that break the skin barrier are tailor-made for the spread of bloodborne infections. These are high-risk procedures conducted in a country with staggeringly high rates of hepatitis B and C, the two most serious bloodborne infections in the hepatitis family (1). Though the Singh dentist duo are obviously fulfilling a need in the community, they’re doing it with quack science and medicine. These guys can’t possibly deliver good healthcare beyond performing primitive mechanical work. What they’re really doing is jeopardizing their clients’ health by performing medical procedures with no regard to the spread of possible infections from the environment, themselves and from their own customer’s bodies.

A few public health studies conducted in India have found that street barbers in particular are quite adept at spreading bloodborne infections. A 2010 study found that patronage of local barbers in Bangalore was a major risk factor for hepatitis B virus among blood donors; a customer that frequents barbers in this fast-moving technology hub is more than four-times more likely to carry the hepatitis B virus (2). Another study found that visits to roadside barbers was a major risk factor for hepatitis C (3). Getting tattooed in the country is also another predisposing and risky behavior (4).

“Dentist of Jaipur” points out that the dental work by the Singh duo can cost as little as  80 rupees, about $1.50 today. For most people in India that live on less than $2 a day, this is already an expensive transaction so imagine the costs of receiving care from trained professionals with, as the elder Singh puts it, “fancy chairs, fan, servants, x-ray and other gadgets (5).” Though Doc Junior compares the work they do to fixing a bike, these guys aren’t replacing a bike’s inner tube or aligning its wheels – they’re tampering with a temperamental ecosystem of bone and tooth and blood and bacteria. Whatever analogy you try to extend this to, our mouths are not anything like bikes.

The street dentists are clearly fulfilling a much-needed service but that cheap and fast procedure, whether it’s a new tooth, tattoo or clean-shaven face, comes a much greater price – gambling with one’s long-term health. So, please, reconsider that appointment you made with your local street dentist.


Infections such as hepatitis B and C may be spread at the Hajj, the annual Muslim pilgrimage to Mecca, due to the unygenic practices of street barbers that shave the faithful following the end of their pilgrimage. You can read my article about the phenomenon at Buzz Kill: Blood-Borne Disease Transmission at the Hajj.

There are SO MANY photos of street dentists on Flickr. Go here to take an Internet nosedive into this niche of street culture.

Wikipedia has a nice little article on the phenomenon of street dentists here.


(1) Abraham P (2012) Viral hepatitis in India. Clin Lab Med. 32(2): 159-74
(2) Jagannathan L et al (2010) Risk factors for chronic hepatitis B virus infection among blood donors in Bangalore, India. Transfus Med. 20(6): 414-20
(3) Thakral B et al. (2006) Prevalence & significance of hepatitis C virus (HCV) seropositivity in blood donors. Indian J Med Res. 124(4): 431-8
(4) Kumar A et al. (2007) Prevalence & risk factors for hepatitis C virus among pregnant women. Indian J Med Res. 126: 211-215
(5) “India – New Global Poverty Estimates“. World Bank. Accessed on February 19, 2013.
Abraham, P. (2012). Viral Hepatitis in India Clinics in Laboratory Medicine, 32 (2), 159-174 DOI: 10.1016/j.cll.2012.03.003

June 5, 1981. Pneumocystis Pneumonia. Los Angeles.

The Pump Handle, an online “water cooler for the public health crowd”, have been publishing a series of articles on Public Health Classics, “exploring some of the classic studies and reports that have shaped the field of public health.” From lead poisoning to the Surgeon General’s 1964 report on the implications of cigarette smoking, the series makes for engrossing material about how our health and standards of living have radically changed due to pivotal research and medical findings.

The front page of the MMWR's June 5, 1981 report that included the first report on what would later be discovered to be AIDS.

The front page of the MMWR’s June 5, 1981 report that included the first report on what would later be discovered to be AIDS.

I’m very grateful that the ladies that blog at The Pump Handle, Liz Borkowski and Celeste Monforton, have given me an opportunity to submit my own interpretation of a Public Health Classic. I focused on a succinct report published in 1981 in the CDC’s Morbidity and Mortality Weekly Report (MMWR) reporting a very unusual outbreak of Pneumocystic pneumonia in Los Angeles among young gay men, which the public health world would later  discover to be the first ever published report on the HIV/AIDS epidemic. This fungal pneumonia is now known as a common opportunistic infection in people with HIV/AIDS but at the time it was rare infection among many other odd fungal and viral infections, blood cancers and strange symptomatology afflicting scores of gay men across the country and physicians were baffled as to the underlying culprit. As Liz wrote in an email in our back and forth correspondence, “it’s so chilling to think back to 1981 and how these physicians had no idea they were witnessing the start of [a] horrific global pandemic.”

As I write in the article,

“In just a decade, AIDS would be the second leading cause of death in young men 25 to 44 years in the United States and would have infected over 8 to 11 million people worldwide. The most recent estimate for the number of people worldwide living with HIV/AIDS is 34 million in 2011, with 68% residing in sub-Saharan Africa. That year, there were 2.5 million new HIV infections and 1.7 million AIDS-related deaths … The June 5th report is a symbol of a time before HIV/AIDS became ubiquitous, before it became a pandemic, before a small globular virus became mankind’s biggest global public health crisis.”

Check out my article “Public Health Classics: The First Report of AIDS” at The Pump Handle and see the original 1981 report here.