If 10-20 ug/L would mean a loss of 1-2 points of IQ it’s unlikely that the animal studies were strong enough powered to pick up such an effect.
If the aluminium goes into the brain that would mean you wouldn’t see it in the blood or hair.
If you want to make a statement about it not going to the brain you either have to account where it went or look in the brain.
If 10-20 ug/L would mean a loss of 1-2 points of IQ it’s unlikely that the animal studies were strong enough powered to pick up such an effect.
If the aluminium goes into the brain that would mean you wouldn’t see it in the blood or hair.
If you want to make a statement about it not going to the brain you either have to account where it went or look in the brain.