When police in the United States pull over a driver on suspicion of "driving under the influence," about half the time that influence turns out to be illegal drugs. Proving the presence of drugs requires a blood test that takes weeks to analyze. So LifePoint, a medical diagnostics company in California, has developed a way to test for up to 10 drugs in five minutes by examining saliva.
"Basically your saliva is made from plasma, the liquid portion of blood," says Linda Masterson, president of LifePoint. Measuring the drug levels in spit, along with its acidity, can provide an accurate read of the dose present in a person's bloodstream. LifePoint's device uses a pump to draw saliva into 10 columns, each containing an antibody that reacts with a specific drug. If any of that substance is present, the antibody binds to the drug and releases a fluorescent compound. This process, invented by the Navy, was used to search for airborne particles from chemical weapons during the Gulf War. LifePoint's Impact system has undergone pilot trials in 10 countries and is now being tested in the United States.