is very controversial, how much marijuana in your system would trigger a positive test? it's very, very controversial here. also, i will point out, though, that the industry says the statistics show that since medical marijuana has become so prevalent in colorado that many problems such as teen drug use and driving under the influence of alcohol have actually gone down. they argue that it's actually going to be a benefit for public safety in the state of colorado, kyra. >> it will be interesting to watch. casey, thanks so much. well, still to come, terrorists strike and tensions climb. in russia as concerns grow over the upcoming winter games. that's right. it's 39 days until the games begin. can russian authorities keep athletes and visitors safe after terrori terrorists strike a city not that far from sochi. more on that in a moment. i'm only in my 60's.