"The levels of radioactivity are negligible," says Collins. "Bananas are not as radioactive as Brazil nuts and they are safe to eat in moderation."

Are they building up for a sequel of this article?

From Wikipedia:

Brazil nuts contain small amounts of radium, a radioactive element, in about 1–7 nCi/g or 40–260 Bq/kg, about 1000 times higher than in several other common foods. According to Oak Ridge Associated Universities, this is not because of elevated levels of radium in the soil, but due to "the very extensive root system of the tree.