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Precision Health September 20, 2018

The "exposome" revealed: a barrage of bacteria, chemicals, microscopic animals and more

By Hanae Armitage

Scientists have measured the human "exposome," or the particulates, chemicals, and microbes that individually swarm us all, in unprecedented detail.

For two years straight, Michael Snyder, PhD, professor and chair of genetics at Stanford, sported a peculiar accessory — a little gray box strapped to his bicep.

The rather mundane-looking rectangle is actually an active gadget specially engineered to do something pretty extraordinary: Suck in and collect tiny samples of the microscopic environment that swaddles us all.

It turns out, at any given time, we are bombarded by a combination of microbes, fungi, chemicals, viruses, particulates and even tiny microscopic animals, a new paper in Cell reported. This whirling plume of particulates is called the human exposome.

The results of the study, which was led by Snyder and lead author Chao Jiang, PhD, a postdoctoral scholar, are the first to reveal such intense detail of the exposome "cloud," both in terms of what's in the environment overall, and what floats in our immediate surroundings. It also shows just how different exposome composition can be, even in relatively small geographic regions — in this case, the San Francisco Bay Area.

I explain in the press release:

For two years, the scientists collected data from 15 participants who traversed more than 50 different locations. Some people were monitored for a month, some for a week, and one (Snyder) for two full years. To capture bits of each individual's exposome, a small device that straps snuggly to the participant's arm 'breathes' in tiny puffs of air — about one-fifteenth the volume of an average human breath.

The device contains a tiny filter that traps particulates and microscopic matter, which eventually gets extracted, analyzed and catalogued in Snyder's lab.

This idea — to siphon up bits of an individual's exposome and systematically categorize what's in it — is quite novel, Snyder said. And it required Jiang to stitch together an entirely new database. 'Scientists had assembled separate bacteria, viral or fungi databases, but to fully decode our environmental exposures, we built a pan-domain database to cover more than 40,000 species,' Jiang said. It includes information on bacteria, viruses, fungi, animals, plants and more, all organized in a single searchable database.

From the data collected on himself, Snyder was even able to deduce that he's likely allergic to the springtime eucalyptus — rather than pine — which is what he suspected gave him allergies prior to the exposome project.

The long-term goal, Snyder said, is to simplify the device into something that resembles an exposome-monitoring smart watch that can suck up and analyze the atmosphere on its own. That's still a ways off, but the idea is to enable everyone to be able to monitor their personal exposome and potentially use the data to improve their health.

Photo by Dartmouth College Electron Microscope Facility

About Stanford Medicine

Stanford Medicine is an integrated academic health system comprising the Stanford School of Medicine and adult and pediatric health care delivery systems. Together, they harness the full potential of biomedicine through collaborative research, education and clinical care for patients. For more information, please visit med.stanford.edu.

Hanae-Armitage

Associate director, content strategy

Hanae Armitage

Hanae Armitage is the associate director, content strategy at the Office of Communications. She helps guide storytelling on digital, editorial and multimedia platforms and covers artificial intelligence, genetics and biomedical data science. She also leads the production of the Stanford Medicine podcast Health Compass, which features the latest medical research at Stanford Medicine and the compelling stories of those who lead it. She is a proud banana slug (a University of California, Santa Cruz alum) and earned her master’s degree in science journalism from Boston University. Outside the office, she enjoys the outdoors, whether it’s a good hike or a dip in the ocean.