The "normal" lead content in human blood is about 0.40 part per million (i.e., 0.40 g of lead per million grams of blood). A val
ue of 0.80 part per million (ppm) is considered to be dangerous. How many grams of lead are contained in 6.0 x 10^3 g of blood (the amount in an average adult) if the lead content is 0.62 ppm?
0.62 parts per million means that there are 0.62 g of lead per million grams of blood (10⁶ grams of blood). In order to find the grams of lead on 6.0 × 10³ grams of blood (the amount in an average adult), we will use a conversion fraction.
6.0 × 10³ g blood × (0.62 g Pb/ 10⁶ g blood) = 3.7 × 10⁻³ g Pb