Halloween is an odd celebration. Parents warn children 364 days a year about the dangers of “taking candy from strangers,” then drive them around to do that very thing one day out of that year. And for decades, parents have been warning children about the dangers of anything they score on Halloween that is not sealed in plastic. Gone are the days of homemade cookies, popcorn balls, and other non-store-bought treats.

While most reports about Halloween candy laced with poison, needles, or drugs turn out to be bogus, there is a newer concern this year that does bear some attention: marijuana-infused candy.

This is not a matter of some sick individual intentionally baking pot brownies to give out to unsuspecting kids on Halloween. Marijuana-infused candy is a real item, available commercially in dispensaries and other places, for people who choose to ingest their THC that way rather than deal with the dangers inherent in smoking anything.

The Denver Police Department spoke of this in a recent podcast. Sergeant Brett Hinkle said, “Apples, gummy bears, there’s a ton of different edible stuff out there on the market that’s infused with marijuana.”

“What’s happening a lot with the edible manufacturers who have focused on a hard or a soft candy is that the most cost-effective way for them to bring that to the market is to use knock-off candy,” said Patrick Johnson, owner of Urban Dispensary. “So they’ll buy it in bulk form, then they infuse it by using viscous hash oil. They spray that onto the candy and once that candy dries, there’s really no way to tell the difference between candy that’s infused and candy that’s not infused.”

That sort of bulk production will be a thing of the past in 2016. Colorado has passed a law that by Jan. 1, 2016, all marijuana-infused candies and other treats must be shaped, stamped, colored, or marked with a symbol indicating they contain marijuana and are not for consumption by children. But for now, it is impossible to tell an unwrapped marijuana treat from a regular piece of traditional candy.

One huge concern about pot candy is that it takes very little of it to have an effect. A regular Hershey’s chocolate candy bar is considered one serving. But an identical pot-infused chocolate bar is considered five servings. While there is no record in human history of anyone ever overdosing on marijuana, the effects of a single unexpected dose of marijuana on a child could be frightening. Five doses could be a terrifying experience, especially considering the fact that the effects of eaten marijuana last considerably longer than marijuana that is smoked.

Colorado police have gone even further, producing a video featuring Johnson to help parents know how to handle Halloween until the new packaging law goes into effect.

One of the things they recommend is throwing away any candy that you do not recognize as being from a well-known manufacturer, and certainly anything that has been opened or tampered with.

Pro-pot advocates stress that it is highly unlikely that anyone will intentionally distribute pot-infused candy to children on Halloween. Dispensary owners and legal users do not want that kind of trouble. It was, after all, a dispensary owner who worked with Colorado police to produce that video.