Don't worry. We're not about to go full Goop and suggest you have your aura read. (If that's your kind of thing, there's a Buzzfeed quiz that we assure you is nothing less than 100 percent accurate.) We're actually talking about the exposome – the cloud of chemicals, microbes, and particles that follows your every move with the determination of a particularly aggressive hawk. A kind of living, breathing aura, so to speak.
Researchers at Stanford University spent two years analyzing the exposome and its contents using a re-engineered monitoring device roughly the same size as a large matchbox. Their results have been published the journal Cell.
“Human health is influenced by two things: your DNA and the environment,” Michael Snyder, professor and chair of genetics at Stanford, said in a statement. “People have measured things like air pollution on a broad scale, but no one has really measured biological and chemical exposures at a personal level.”
Data were collected from 15 individuals who, between them, passed through more than 66 locations. Each wore a device (nicknamed the exposometer) that "breathed in" tiny amounts of air one-fifteenth the volume of a human breath and trapped particulate matter in its sub-micron filter. Some were monitored for a week, others a month, and Snyder the full two years.
In the lab, the matter underwent chemical profiling and DNA and RNA sequencing to determine what exactly was lurking in each individual exposome. The result: a horrid-sounding concoction of fungi, plants particulates, chemicals, and bacteria.
"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," Chao Jiang, a postdoctoral scholar, explained. They collected approximately 70 billion readouts in total.
Despite living in close proximity (all volunteers were residents of the San Francisco Bay Area), the individual exposomes were wildly different. Each had a unique "signature" influenced by their environment and exposure to pets, cleaning chemicals, etcetera – though the insect repellant DEET and several known carcinogens were found in almost all samples.
For example, the exposome of a volunteer living in San Francisco displayed higher levels of "sludge bacteria", normally found around sewer water. Meanwhile, Snyder's revealed above-average counts of fungi – possibly due to the green paint his environment-conscious decorator used.
"The bottom line is that we all have our own microbiome cloud that we’re schlepping around and spewing out," Snyder added.
The researchers were also able to pick out seasonal differences between the samples. Green leaf plants, for example, were (unsurprisingly) more abundant in spring and summer, whereas levels of Basidiomycota fungi peaked in winter and spring.
The authors say this research could one day be used to clarify environmental influencers on health, whether that's providing more nuanced information on what's causing your seasonal allergies or how different levels of carcinogens affect cancer risk. Director of the Microbiome Center at the University of Chicago Jack Gilbert, who reviewed the study for the journal Science before it was re-submitted to Cell, is more critical.
"At best, this is an observational study that says: When you move about, you're exposed to different things. But it doesn't really go beyond that," he told Wired. He is, however, very excited by the exposometer, saying the study's most important contribution is technical rather than scientific. "Don't get me wrong – I love the work, but I question its impact on our current understanding of people's exposomes."
Next steps are to monitor more people in more diverse environments. Snyder hopes that one day everyone will be able to keep track of their exposome, perhaps using something "like an exposome-detecting smartwatch".