Alright, I'm going to throw my hat into this a little bit. Aluminum was proported in the 60's and 70's to cause alzheimers, but no direct association was ever made. It is, however toxic, as mentioned before. You can find more information about the toxicity here:
Aluminum Toxicity
So why is it used so often in food storage if it is toxic you ask? Well, when exposed to oxygen, a very thin, but resolute layer of aluminum oxide forms, which is non-toxic, and it forms very fast. Aluminum itself does not contain lead. They are two seperate elements. However, many aluminum products do have lead in them. Keep in mind though that the bridge in 510s is aluminum mesh. Any problems you would expect from this mod could also be expected simply from the atomizer.
The concern with electrolysis and the decomposition of the metals is possible. The filament used for atomization can vary from manufacturer to manufacturer. I don't believe that this mod adds any additional risk, and there have been no reports of metals being found in vapor. Further I don't believe that they would remain in the vapor, nor do I think that they would be able to escape the electromagnetism created by the electrical current in the atomizer. I think the biggest factor in the marine environment with regards to electrolysis is the fact that you are in salt water, and that water is grounded. The boat itself becomes a big battery, which is the reason the metal decomposes. It is generating its own electricity from the combination of ferrous and non-ferrous metals in an acidic solution. In the instance of an electronic cigarette it is not grounded, and you already have a battery. =P
There are acids found in the juices, usually from the flavoring.
Totallywicked shares a lab report they had done on their juice, which lists 2Methyl butyric acid in amounts of less than 1 percent. There are other chemicals there as well, so it is hard to judge for certain what the PH balace of juice is, and I suspect that it will be different from juice to juice. First you will need to look up the PH level of PG or VG, as these are the main ingredients.
Please note that I am not really a scientist, or a doctor. This is all purely speculation. Do your own research and don't get hurt.