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Recent leaps in both analytics and genomics technologies – along with a recognition that studying the genome alone wasn’t going to produce a complete picture of human health – have propelled the field. “It was very clear that the environment part had to be plugged into this,” said Gary Miller, director of the HERCULES Center. Interest in the exposome is particularly high for those studying children’s health.

Steve Rappaport, an environmental health professor at the University of California at Berkeley and director of the Berkeley Center for Exposure Biology, for instance, is studying blood samples from about 3,000 newborns to see what differences they may show between those who developed leukemia later in childhood and those who did not. Because genetics contributes little of the risk for childhood leukemia, Rappaport said, he’s on a hunt for what in the environment causes it.

Previous efforts to pinpoint environmental causes of disease have usually involved a hypothesis that substance X leads to condition Y – which essentially amounts to guesswork, said Rappaport, because that approach involves testing specific substances rather than casting a wide net to find anything and everything that might get caught. In other words, looking for one thing almost precludes finding anything else.

“The idea of [the exposome] is, you don’t guess. You look for everything you can measure,” he said. He thinks his team has identified three or four molecules in the blood that seem to predict development of childhood leukemia and are environmental in nature, meaning they are not genetic and resulted from external exposure or even internally, such as from diet or stress.