Dots on old expired films... where do they come from?

Recently I wrote a film review (in german) about a special film which was covered over and over with blue and red dots: http://www.lomography.com/magazine/reviews/2010/11/27/agfa-rsx-200-professional-seit-11-jahren-abgelaufen-und-mit-seltsamen-effekten

In this review, some people started to discuss where these dots could come from. A working collegue of mine, which is very experienced with cameras, said, that it’s maybe the condensation water after cooling the films in a fridge or a freezer. I used many old and expired films, but tis only happened twice to me. The second one was in one of my latest albums, and there are only a few dots. I got this film from somebody who had also cooled it, and the first one I got from ebay.

Here are some more examples from other users of the community:

Is there any photo geek outside here who knows the answer? First I thought that it is something like a joke, and somebody just sold me a film where he exposed some dots before. But this happens often enough to say that it’s not a joke, but not often enough to know more about it. I somehow like the dots and would like to have more spotted films!

The brands of the films are: Agfa CT Precisa 100, Agfa CT Precisa 200, Agfa RSX, Konica Chrome 100

Additional pictures: a scan of the negative (positive and negative):

geschrieben von shoujoai am 2011-03-15