Not only is the finding that nanotubes “remained in particular in the liver and spleen” of concern, but there is no indication made or concern expressed over what happens after excretion. What biological activity do these structures have in the open environment, and for how long? Can they become airborne? Do they get removed in sewage-treatment plants? After all, these things have never existed before.
William Belknap Boulder City, Nev.
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