Though a common word in everyday language, exposure must be very precise in medical research, such that even entire papers are written on it. It refers to anything a person is literally exposed to—whether a drug, a contaminant, a type of family situation, a prenatal exposure in the womb, something genetic, an experience (such as traumatic events), a benefit, membership in a particular social group, environmental factors, a therapy or intervention, etc.—that is measured and explored with regards to associated outcomes. In other words: who was exposed and how much? What were their outcomes? Were the outcomes related to the exposure?
Deeper dive
Though seemingly simple, exposure can get extremely complex when it comes to characterizing and measuring it, and journalists should pay attention to how researchers do just that. Consider, for example, trying to measure poverty as an exposure—there are countless ways to define, characterize and measure poverty. Some, such as income level, might seem direct but may not take into account non-financial counters, such as a strong family or community network that someone with a slightly higher income and no safety net doesn’t have. Sometimes proxies are used for exposure, such as using parents’ education levels to assess a child’s likely exposure to new vocabulary words.
Even when talking about straightforward exposure to a specific substance, such as prenatal exposure to diethylstilbestrol, it’s anything but straightforward: Researchers must consider dosage, route of exposure (DES was primarily ingested but other routes for different drugs include injection, topical and inhalation), duration of exposure, trimester of pregnancy, etc. A study on prenatal alcohol exposure must also consider dosage, duration and trimester in addition to co-exposures, such as smoking or healthy diets. And speaking of diet… it’s among the most complex exposures that researchers can explore, which partly explains why nutrition research findings are all over the place.
When covering a study that involves exposure, look at how it was defined, characterized, and measured, and what they might not have measured (Duration? Timing across lifetime or age of exposure?). Then ask them why they chose those parameters for defining and measuring exposure and what alternatives they, or another researcher, might choose instead. Sometimes the only reason they define exposure in a particular way is because it’s the only form in which they have data — which could lead to more questions about the quality of the data collection.