Perhaps someone who has more knowledge can elucidate me, but when they say "diluted by the Pacific ocean", I think the implication is that it is like dumping a million gallons of Kool-Aid in the ocean - it would disperse so much that the things that identify it as Kool-Aid - color and sweetness - would essentially disappear into the soup.
However, as I understand it, we are talking about irradiated particles. The radiation does not "dilute", right? It is like adding 2-3 deadly ping pong balls to a sports arena full of ping pong balls. The chances of encountering one are slim, but, if you do, you could die or be seriously hurt. ( I am talking about ingestion ).
And, it's not like the risk of ingestion is a function of the volume of the ocean necessarily, as there are specific vectors of distribution - mainly things like seaweed, krill, tuna, etc. that are small compared to the mass of the ocean, but significant in likeliness of human contact due to the over fishing and reliance on the ocean for food.
So, am I looking at a greater risk of ingesting a particle of cesium when I eat my canned tuna and having it give me cancer - or are we really saying that the properties of radiation are somehow lessened by contact with so much sea water?