deadly. i'm starting a new account, and i'm a teenager, how many degrees away from a drug dealer am i? >> in my experience, two. >> reporter: cbs news asked miles to create two fake profiles across instagram, snapchat, and tiktok, claiming they were 18 but publicly identifying as high school students. one was actively searching for drugs. >> i just messaged, "hey, do you have xanax?" >> reporter: and within just 48 hours, found an apparent dealer. the second account used different hash tags like... >> depression, sad, anxiety. >> reporter: while all three platforms provided some mental health resources, posts about marijuana and cigarettes also appeared on instagram. >> by the third day on instagram, we were fully immersed into drug culture. >> reporter: who bears the responsibility? >> it's the tech companies. since they aren't liable, they're not creating the guardrails needed to keep our kids safe.