Misconceptions and Fallacies

[miketsp]

It wouldn't nessecarilly be that much blood. The mistake is that you are using "part" as in the cooking meaning (volume for volume), in chemistry "part" means molecule or atom, and the atoms or molecules aren't the same size. Because of that there could be the same number of parts, with out the volume being the same.

This was a rough calculation to show order of magnitude in an assumed cylinder.
But if it comes down to it I just checked various scientific articles published on the Internet and all of them equate ppm to mg/Liter. Given that blood density is very close to 1, only around 5% greater and even then subject to postural changes of the subject, your comment would seem to fall into the class of unnecessary nitpicking.

I could just as easily have assumed a cylinder 5% smaller or larger.