I hate to be anti breast feeding but yes, the mercury goes into the milk. They forget to tell women that breast is best...IF your healthy! I also breastfed my son for 4 months...and for his sake not exclusively. Getting someone to test your baby might be a bit tricky. I had them test my 9 year old with a blood test...as they did not know how to test her either. They wrote it up as "heavy metal test" so the insurance would ok it. Her levels were like 1..which they said is normal. But since blood tests only indicate recent exposure....a 1 indicates to me that she is getting exposed daily! It really shouldn't be there at all.

I would get your son on children's mulitvites if he isn't already. This will help keep his system strong and obviously no more breast milk if he is still nursing Mercury seems to be responsible for many of the behavioral and learning disorders we see in young children. Don't be alarmed yet...he is probably fine.

I will finally be getting a hair analysis myself. It seems to be one of the few ways to test mercury. The challege test can make people sick. Mainly...get the metal out! I figure the main things that matters is removing it, now how much we have. Any amount is bad.
As far as cancer...yes, all research I have read says that mercury is carcinogenic!
My father who carried 16 amalgams all his adult life suffered a rare form of thyroid cancer. They have no idea how he got it...said it was "enviornmental". They did fail to recognize all the other symptoms he has..which are mercury induced.