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MSU research: Eating brown rice increases exposure to arsenic compared to white rice
(msutoday.msu.edu)
While there are no major health risks for the general American public, there are potential health concerns for infants and children under age 5, as they consume more food relative to their bodyweights than adults.
“While we found that choosing brown rice over white rice would result in higher arsenic exposure on average, the levels should not cause long-term health problems unless someone ate an enormous amount of brown rice every day for years.”
It's something to be mindful of, but shouldn't be a major concern for most people.