For decades, scientists have been carefully unraveling the role of genes in disease by examining how small variations in a person’s genetic code can shape lifelong risk of developing common conditions such as cancer, diabetes, or heart disease. But genetics only tell part of the story.
The other part comes from all the external and internal exposures a person experiences during their lifetime, which can range from pollution to infections to diet and lifestyle. Cumulatively, these exposures—and the body’s biological response to them—make up what scientists have termed the exposome.
A team led by scientists at Harvard Medical School has now conducted what may be the largest-scale study to date to quantify the relationships between exposures and health outcomes, testing more than 100,000 associations. The work demonstrates the importance of studying potential environmental disease risks in aggregate rather than one at a time.








