How harmful is the white residue from soda crystals?

[yashicamat]

I cleaned my boiler with soda cystals last night after the work I'd done on it. I rinsed very thoroughly, but yet this morning there was a think white residue on the metal fittings inside. I gave it another good rinse, including one with hot water, confident that would shift it.
I was about 10 minutes into the sparge this morning and I noticed the residue was still on the pipes where the water had dried. The wort level was already covering most of the elements and the copper frame of the hopstopper, but I cleaned up what I could get to with a piece of damp kitchen towel, including the walls of the boiler. Chances are though, there was some present on the frame despite the repeated cleaning. Are soda crystals very harmful? Or in other words, am I likely to get away with it when diluted down with 25 litres of beer?

Cheers.

[yashicamat]

Don't worry they are sometimes used as an addative in water treatments when making beer and apparently can be added to the sprouts to stop them from loosing their colour when boiling them to death.

Cheers Chris.