Mounting evidence from places plagued by naturally occurring arsenic that contaminates the groundwater shows that chronic exposures to high levels (greater than 100 ppb) contribute not only to cancer but also diabetes, cognitive deficits, cardiovascular disease. But what nobody knows for sure—and what Ana Navas-Acien, MD, PhD, from John Hopkins University is committed to figuring out—is whether even low exposures to arsenic are harmful over the long haul. And: Can genetic and environmental factors make seemingly insignificant chronic exposures especially bad for certain people? Read more at John Hopkins' website.