We're looking at what outcome we are concerned with. Obviously if we're looking at major structural changes in the brain, we wouldn't expect to see that with one in four times use, sir. Then when we're looking at driving, if you've only used once in the past year and you're intoxicated that one time and you get behind the wheel of a car, that's clearly going to have a negative outcome. It just depends on what outcome you're looking for.
We would not have expected Dr. Smith's research to show somebody who had smoked a year or six months ago to show those changes in the brain, because she was looking at people who had it in their urine; current users were those people explored. Clearly we wouldn't have seen among heroin users structural changes in the brain if they had used one to four times in the last year.