I don't think there should be a cap. We're still learning about the health impacts from Hiroshima and Nagasaki, as well as from Chernobyl, and intergenerational impacts are just that--they're intergenerational, so we won't necessarily see them show up. It will take a great deal of study to trace it back to what the original impacts are at the population level.
On November 27th, 2007. See this statement in context.