1 part per billion (1 ppb) is a descriptive expression, usually used as a unit of measurement. Simply, it means that for every 1,000,000,000 parts, then 1 is of the nature described. This could mean in 1,000,000,000 balloons, one is red and the others white. It's a term commonly used in toxicology to describe things such as a diet administered (rats consumed a diet containing 1 ppb ethinyl estradiol). It allow a way of comparing things such as doses (rats consumed diets containing 1, 5, or 200 ppb). Sherry Ferguson, Ph.D Research Psychologist National Center for Toxicological Research/FDA 3900 NCTR Road Jefferson, AR 72079 > -----Original Message----- > From: Michael Sylvester [SMTP:[EMAIL PROTECTED]] > Sent: Wednesday, April 18, 2001 8:37 AM > To: TIPS > Subject: Toxicological research > > > can anyone explain to me statistical expressions such as: > 1 part in a billion. > This caught my attention because of the discovery of arsenic > in a number of playgrounds in the Central Florida area. > > Michael Sylvester,PhD > Daytona Beach,Florida > > > > >
