The Centers for Disease Control (CDC) defines the exposome as:
“...the measure of all the exposures of an individual in a lifetime and how those exposures relate to health. An individual's exposure begins before birth and includes insults from environmental and occupational sources.”
In other words, the exposome is the ultimate measurement of every substance an individual has ever been exposed to, whether dioxins and phthalates, chemicals in pesticides and flame retardants, or viruses and bacteria. Total exposure is tracked even before birth, and lasts a lifetime.
Why is the exposome important?
The exposome is important because it examines cumulative exposure -- exposure over time -- to potentially harmful substances, rather than one-time, or acute, exposures. This is a ground-breaking point of view, in that the way toxicity is generally defined for a given substance is primarily from the perspective of a single encounter.
Take bisphenol A (more commonly known as BPA) for example, which has been linked to heart disease, diabetes, and liver failure. Acute exposure to the amount of BPA that has leeched into the contents of a can of soup is highy unlikely to cause health issues in an adult human. Frankly, even if a can of BPA-lined soup were to be consumed weekly, chances are, the body would be able to rid itself of the BPA without much trouble.
Unfortunately, BPA isn’t just in that single can of soup -- it’s in many soups. It’s also in some bottled waters (primarily the caps), baby formulas, canned carbonated beverages such as soda and beer, plastic take-out containers, canned fruits and vegetables, PVC water pipes, baby bottles, dental sealants, detergents, shampoos, and plastic dishware.
In other words, by the time an adult reaches his or her mid-30s, their cumulative exposure to BPA may very well be enormous. Using the exposome perspective, that adult’s BPA exposure would be analyzed starting before birth (that to which they were exposed via their mother’s diet or lifestyle factors), continuing right after birth (baby formula and bottles, breastmilk; even baby shampoo), then into childhood via canned foods and plastics, through the teenage years and on through adulthood. While the bulk of BPA is excreted within about 9 hours, the remainder is stored, often in body fat. And the more of it we consume, the more we cumulatively store. So while BPA may not be acutely toxic, it can certainly be toxic when consumed regularly via multiple avenues.
The Exposome: Measuring a Lifetime of Multiple Cumulative Exposures
What makes the idea of the exposome unique is that it takes into consideration not just the cumulative effects of exposure to a single potentially toxic or damaging substance, like BPA, but all substances to which one has been exposed over a lifetime. So every daily exposure to a paraben containing shampoo, occasional exposure to secondhand smoke, BPA exposure in the womb, indoor air pollution from paint VOCs as a child, phthalates in a favorite perfume or indoor air freshener, outdoor air pollution from 5 years of urban living, pesticides consumed over a lifetime of eating fresh produce, etc. -- all of these (and many, many more) are part of an individual’s personal exposome. It’s the cumulative and additive exposure to all of these substances when examined at as a whole that ultimately matters, and what researchers want to better understand regarding its impact on human health and wellness.
Shannon Eggleton is Vice President of Aeroscena®, a leader in aromatherapy and safe scent research. Aeroscena formulates and produces clinical aromatherapy and functional fragrance health and wellness products for hospital and home use under the Ascents® brand name.