Teen Usage Up in Legal Pot States:  One of the most repeated promises from legalized marijuana advocates has been that allowing the government-regulated sale of the drug will assure that children do not have access to it.  Jennifer Oldham of the Washington Post reports that in the first two states to legalize recreational pot, parents, educators and physicians report that teen usage has increased with often devastating results.  In the Denver area, visits to Children's Hospital Colorado facilities for treatment of cyclic vomiting, paranoia, psychosis and other acute cannabis-related symptoms jumped to 777 in 2015, from 161 in 2005.  A 2018 study by the Journal of Adolescent Health determined that surveys finding that pot use among children has not changed much since 2014, may not reflect the impact of legalization on adolescent health.  Washington's latest Health Youth Survey found that 20% of eighth graders and nearly half of high school seniors consider marijuana to be a low risk activity, although medical and mental health professionals say the impact of high potency pot and edibles is doing major damage to adolescent brains.  "I hope we don't lose a generation of people before we become clear we need to protect our kids' brains," said an adolescent medicine specialist at Seattle Children's Hospital.  But there is a trade off.  Washington raked in $358 million and Colorado reported $266 million in government revenue from pot sales in 2018.