Experts say terrorist groups are seeking materials for a crude nuclear device - a so-called "dirty bomb" - that would have limited blast potential but could spread radiation in a major urban area.

VOA: standard.2010.04.11

It is not particularly easy to get information from the site because of all the reasons that have been cited about the potential radiation emissions and the damage done.

WHITEHOUSE: Press Briefing

As we watch the events in Japan, it is understandable that people are worried about the potential of nuclear radiation fallout in our community.

FORBES: Radiation No Threat To Silicon Valley, Santa Clara County Says

The effects of radiation only start to become clear at high acute absorbed doses of over 1 Sv (100 rem), and even then it is necessary to eliminate other potential causes before radiation can be unequivocally said to be the cause, advised UNSCEAR.

FORBES: Like We've Been Saying -- Radiation Is Not A Big Deal