Tennessee Sen. Marsha Blackburn is warning parents about a new trend in the world of dangerous and illicit substances.

The Drug Enforcement Administration (DEA) in August seized brightly colored fentanyl pills in 18 states. Fentanyl is a synthetic opioid that is up to 50 times stronger than heroin and can be deadly in doses as small as two milligrams. A new variation of the drug can be found in the form of pills that look like candy or powder that looks like sidewalk chalk.

Blackburn and other GOP leaders issued a PSA video on Tuesday advising parents to stay cautious of rainbow fentanyl as Halloween approaches.