"Picogram" Natural Recordings by Native Speakers
A picogram is a unit of mass in the International System of Units (SI). It is one-trillionth (1 × 10−12) of a gram. It is a very small unit of mass.
A measure of radioactivity. One picocurie (pCi) is the amount of radioactive material that decays at a rate of 2.22 nuclear transformations per second.