Twenty states and the District of Columbia have passed laws legalizing marijuana for some medical purposes, and two states, Colorado and Washington, have legalized marijuana for recreational use. Whether you live in these states or not, the implications of these laws are far reaching.

Researchers at New York University’s Center for Drug Use and HIV Research surveyed almost 10,000 high school seniors about their attitudes toward marijuana. The survey found that 10% of seniors who don’t currently use marijuana said that they would try it if the drug were legal. Additionally, the survey found that there was a reasonably high percentage of students who adults wouldn’t suspect of drug use – students who were are very religious, do not smoke, or do not drink alcohol – who said they intended to try marijuana if it becomes legal.

In Colorado, the latest booming business is marijuana-laced snacks, such as chocolate-peppermint Mile High Bars and peanut butter candies infused with hash oil. Retailers say the products are popular with customers who want to experience the effects of marijuana without smoking and coughing. Critics say the snacks are ending up in the hands of teens who want to get high discreetly, or children who don’t know they contain marijuana.

Before the marijuana-legalization laws passed, almost 15% of American teens between the ages of 12 and 17 reported using marijuana in the past year, according to the National Institute on Drug Abuse. Experts agree that these numbers will climb substantially. Even if adolescents do not reside in states with legalized marijuana, the message that these laws imply is that marijuana use is acceptable and safe.

Unfortunately, according to the National Institute for Drug Abuse, estimates suggest that one in six people who start using marijuana as teenagers become addicted to the drug. While dependence is not life-threatening, it does have serious adverse effects on cognitive functioning. The most disturbing new studies about early teenage use of marijuana showed that young adults who started smoking pot regularly before they were 16 performed significantly worse on cognitive tests of brain function than those who had started smoking later in adolescence. Long-term, marijuana smoke contains 50% to 70% more cancer-causing substances than tobacco smoke. Additionally, many advocates of marijuana do not realize that today’s drug is much more potent than it once was. Research has not been done on the long-term effects of marijuana use, nor on the impact of the higher potency drug. Finally, if marijuana use becomes legal, and more people, including youth, use it before driving a car, we can be sure that drug-related accidents will increase. Marijuana use causes disorientation and lack of coordination.

Parents should take the time to talk to their teens about their opinions on marijuana legalization and inform them of the negative consequences.