Blood Drug Testing

Why isn't saliva used instead of blood for lab tests?

Since everyone's saliva contains tiny amounts of their blood, why can't a saliva sample be used instead of having to use a hypodermic needle to draw blood for a test? It would be a lot less invasive, and easier, to use a swab to get some saliva. Isn't technology sophisticated enough (yet) to detect the blood in the saliva?

Public Comments

1. there might be traces of blood, but not very much i assume. pure blood itself contains red blood cells, WBCs and plasma. Salive may dilute it or something perhaps.
2. The blood has more DNA information and say if they need to compare DNA, your blood will have more information. But they can use saliva. I guess it also depends on how modern their technology is as well.
3. Because there are traces of what you last ate in saliva. And if you had a drink before testing it would mix with it.
4. your right, taking saliva as DNA blood test is less invasive, but if you would make comparisions between the blood to the saliva the blood is more effective in determining it because it is more pure. Maybe, in my own opinion saliva can sometimes not be completely dependable when it comes to taking DNA tests. Who knows who's "other" saliva is in your mouth after making out with a person. I mean besides that there are also many factors, maybe some disease in the mouth perhaps, or even some other chemical substituents that are mixed in the food you have taken( and are left around the oral cavity) that can also disrupt the taking of the DNA tests, and more. There are more disadvatages in taking DNA tests through saliva sample rather than in blood sample. I can't state any much more about its advantages anymore(for the reason that i can't recall), but this is what I think only...
5. If you are talking about DNA tests, they can actually swab the inside of your cheek to get DNA. It scrapes off some skin cells, and is non invasive. Blood is actually not a great source of DNA because most of the cells are red blood cells, which have no chromosomal DNA. If you are talking about typical blood tests, there is a reason why blood is used. A standard blood test tests for several things (HDL and LDL cholesterol, blood sugar, liver enzymes, etc.) You cannont do one test on the blood to find out all of that information, you have to divide it into portions and do seperate tests. For a single test, such as blood sugar or iron, a pinprick in a finger is good enough. Lets say a typical blood draw is 5 ml. To get the same amount of blood from saliva, you would have to be drooling into a cup for at least a whole day, and probably longer. This is unhealthy and wastes a lot of time, not to mention the time spent seperating the blood from the saliva.
6. The amount of blood in saliva is far too small to get any meaningful data from, and the saliva would interfere with many of the tests that we send blood for. Sorry, it's still going to require needles and tubes of blood to get much of the information we need to keep people healthy/alive.