Still, addiction specialists continue to warn about the chances for substance abuse. Dr. Aaron Weiner, of Linden Oaks Behavioral Health in Naperville, said the 2.5 ounces of pot allowed every two weeks under the program provides for frequent daily use, which is linked to addiction. He also warned that the marijuana sold in Illinois dispensaries contains up to about 90 percent THC, the element that makes users high, far more than traditional street pot.