Babies stir up clouds of bio-gunk when they crawl

January 11, 2018 by Steve Tally, Purdue University
A robot baby was used to determine how much biological material crawling infants stir up from carpets by a research team led by Brandon E. Boor, an assistant professor at Purdue University. They found that crawling children breathe in four times what an adult would breathe in walking across the same floor. Credit: Purdue University

When babies crawl, their movement across floors, especially carpeted surfaces, kicks up high levels of dirt, skin cells, bacteria, pollen, and fungal spores, a new study has found. The infants inhale a dose of bio bits in their lungs that is four times (per kilogram of body mass) what an adult would breathe walking across the same floor.

As alarming as that sounds, lead researcher Brandon Boor of Purdue University is quick to add that this isn't necessarily a bad thing.

"We are interested in the biological material an infant inhales, especially during their first year of life when they are crawling. Many studies have shown that inhalation exposure to microbes and allergen-carrying particles in that portion of life plays a significant role in both the development of, and protection from, asthma and allergic diseases," Boor says. "There are studies that have shown that being exposed to a high diversity and concentration of biological materials may reduce the prevalence of asthma and allergies later in life."

Scientists have previously done studies to determine how much dirt and biological material is kicked up and resuspended into the air when an adult walks indoors, but this is the first study to look at what happens with infants and their unique forms of locomotion.

Human babies are the only mammals that can't get up and walk soon after being born. Elephants, giraffes, horses, all can take a few wobbly steps soon after they enter the world, but it's months before a human can claim the same accomplishment.

(Anthropologist David Tracer of the University of Colorado has suggested that based on studies of indigenous cultures, crawling is not necessary for human development. In fact, he has suggested, it only became common once people began living in structures with wooden floors.)

As babies roll, slide and crawl on the floor, their movements stir up more particulates into the air, and their mouths and nostrils are much closer to the floor where the concentrations are greater. This is countered somewhat by the fact that babies tend to move in much shorter bursts of activity than do older children or adults.

To study just how much of the floor debris babies breathe, the research team built a robotic crawling baby (which is much less adorable than the real thing) and tested it crawling on actual carpet samples they had removed from homes. Then the researchers measured and analyzed the particulates in the breathing zone.

Credit: Purdue University

"We used state-of-the-art aerosol instrumentation to track the floating in the air around the infant in real-time, second by second. The instrument uses lasers to cause biological material to fluoresce. Most bacterial cells, , and pollen particles are fluorescent, so they can be reliably distinguished from non-biological material in the air," Boor says. "We also worked with a microbiology group at Finland's National Institute for Health and Welfare, which conducted DNA-based analysis of the microbes we collected onto filters."

The researchers found that a concentrated cloud of resuspended particles forms around the Pig-Pen wannabes, and that the concentrations around them can be as much as 20 times greater than the levels of material higher in the room.

Moreover, infants' bodies aren't as good at blocking this dust storm, Boor says.

"For an adult, a significant portion of the biological particles are removed in the upper respiratory system, in the nostrils and throat. But for very young children, they more often breathe through their mouths, and a significant fraction is deposited in the lower airways—the tracheobronchial and pulmonary regions. The particles make it to the deepest regions of their lungs."

Counterintuitively, perhaps, this may be just what nature intended.

In the late 1980s, British epidemiologist David Strachan was the first to propose the "hygiene hypothesis," which says that too clean of an environment may suppress the development of the immune system. Allergists also sometimes refer to this as "the farming effect."

"Exposure to certain bacterial and fungal species can result in the development of asthma, but numerous studies have shown that when an infant is exposed to a very high diversity of microbes, at a high concentration, they can have a lower rate of asthma later in life. Such exposures act to stimulate and challenge your immune system," Boor says.

In Western societies, infants spend nearly all of their time indoors, where indoor dust resuspension may contribute significantly to their respiratory encounters with .

"While our research established new methods for infant microbial exposure assessment, much remains to be discovered," Boor says. "I hope to continue to work with microbiologists and immunologists to better understand the role of indoor air microbes and allergens on early-childhood health."

Explore further: Insight into how infants learn to walk

More information: Tianren Wu et al. Infant and Adult Inhalation Exposure to Resuspended Biological Particulate Matter, Environmental Science & Technology (2017). DOI: 10.1021/acs.est.7b04183

Related Stories

Insight into how infants learn to walk

December 14, 2017
Ten-week-old babies can learn from practising walking months before they begin walking themselves say researchers. They gave the infants experience at "reflex walking" which is a primitive instinct in babies which disappears ...

Asthma in infant boys may eventually be preventable

November 27, 2017
A new University of Alberta study shows that the family risk for asthma—typically passed from moms to babies—may not be a result of genetics alone: it may also involve the microbes found in a baby's digestive tract.

Makeup of germs in newborn's gut may triple allergy, asthma risk

September 13, 2016
(HealthDay)—A relatively rare abnormality in the makeup of germs in an infant's gut may triple the risk for allergies and asthma in childhood, new research warns.

Dogs may protect against childhood eczema and asthma

October 27, 2017
"Good dog!" Two studies being presented at the American College of Allergy, Asthma and Immunology (ACAAI) Annual Scientific Meeting show there may be even more reason to love your dog. The first study shows babies born in ...

Exposure to pet and pest allergens during infancy linked to reduced asthma risk

September 19, 2017
Children exposed to high indoor levels of pet or pest allergens during infancy have a lower risk of developing asthma by 7 years of age, new research supported by the National Institutes of Health reveals. The findings, published ...

Recommended for you

Eating iron-fortified grain improves students' attention, memory

July 18, 2018
Adolescent students in a rural school in India who consumed an iron-biofortified version of the grain pearl millet exhibited improved attention and memory compared to those who consumed conventional pearl millet, according ...

Lowering hospitals' Medicare costs proves difficult

July 18, 2018
A payment system that provides financial incentives for hospitals that reduce health-care costs for Medicare patients did not lower costs as intended, according to a new study led by Washington University School of Medicine ...

Vaping tied to blood clots—in mice

July 18, 2018
A new study involving mice raises another concern about the danger of e-cigarettes in humans after experiments showed that short-term exposure to the device's vapors appeared to increase the risk of clot formation.

People who tan in gyms tan more often, and more addictively, than others, new research shows

July 18, 2018
Gyms are places people go to get healthier. But nearly half the gyms in the U.S. contain a potentially addictive carcinogen—tanning beds, report UConn researchers in the July 18 issue of JAMA Dermatology.

Omega 3 supplements have little or no heart or vascular health benefit: review

July 17, 2018
New evidence published today shows there is little or no effect of omega 3 supplements on our risk of experiencing heart disease, stroke or death.

Study shows that people most affected by alcohol also most impacted by sleep deprivation

July 17, 2018
A team of researchers from the German Aerospace Center and Forschungszentrum Jülich has found that people who are most susceptible to alcohol intoxication are also most susceptible to cognitive problems due to sleep deprivation. ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.