This quote from the 'Similac' website...."Abbott has not detected melamine in any of our infant formulas using the US FDA method.
Both Health Canada and Abbott's internal tests are using a more precise testing method -- the most sensitive, rigorous method in the world -- which is capable of detecting very low background levels commonly found in the environment and in foods.
We regularly monitor and test our ingredients used to make our infant formulas including our milk or milk proteins which are not sourced from China. We have not detected any levels of melamine in our ingredients."
One part in a million is background noise - about 2 quarts in an Olympic-Sized Swimming pool. Remember that if you look hard enough for anything, you'll tend to find it.
I have a family member who works for Abbott in this product line and he recently commented to me that Abbott went to great lengths testing to detect any melamine in their formulas or from where their ingredients originated.
He remarked Abbott is very serious in ensuring the best possible quality of their products.