Opponents of marijuana legalization warned of pot-laced Halloween candy. It never happened.

After Colorado legalized marijuana in 2012 and began sales in 2014, opponents warned of a spooky but unwanted outcome that Halloween: marijuana-laced candy. As opponents put it at the time, deviants would take advantage of the state’s lax cannabis laws to give trick-or-treaters pot-laced candy without their knowledge.

USA Today reported in 2014, “Marijuana-infused candy raises Colo. Halloween concerns.” Denver police put out a video telling parents how to watch out for marijuana-laced candy. Anti-legalization activist Kevin Sabet echoed the concerns, tweeting a news story about marijuana-laced candy in Maryland (though law enforcement said there was no evidence the candy was destined for trick-or-treaters).

So here’s the good news: This never happened. Not even once, based on the available evidence.

I reviewed media reports surrounding Halloween and contacted police departments, hospital networks, and poison centers in Colorado and Washington state, the first two states to legalize recreational marijuana in 2012, to see if there had been any incidents of someone slipping marijuana candy to a trick-or-treater. None of them were aware of any such cases.

This response, from the Denver Police Department, was standard: “We are not aware of any cases of children ingesting marijuana candy during Halloween season.”

This isn’t a scientific study, given that there is simply no comprehensive data available for this kind of thing. But it shows that at the very least, initial fears about pot candy were overwrought.

To some extent, this shouldn’t be surprising. The truth is that scares of dangerous or otherwise contaminated candy, despite playing a prominent role in American culture, are completely unfounded.

As Joel Best, the nation’s top (and perhaps only) researcher on Halloween candy contamination, told me, “I’ve done research, and I can’t find any evidence that any child has been killed or seriously hurt by any candy picked up in the course of trick-or-treating. My view is this is overblown. You can’t prove a negative, but it seems unlikely.”

These kinds of Halloween scares aren’t uncommon. Every year around this season, there are frantic warnings of potentially poisoned candy. Parents and schools will tell kids to watch out for candy in tampered packaging, with some parents even insisting on checking all their kids’ candy before it’s eaten.

These fears are pretty new, as the concept of trick-or-treating is also fairly new in the US. Trick-or-treating largely began as a phenomenon after World War II to, in Best’s telling, counter the shenanigans that older adolescents were involved in during the Halloween season, such as covering houses in toilet paper and tipping over outhouses. Communities figured that if they embraced Halloween and turned it into a mainstream holiday that children could participate in, the pranks — or at least some or most of them — would go away.

As the idea spread and more communities participated, fears of dangerous candy and other hazards also began to pop up fairly quickly.

“The older versions of this that I know of were stories in the early 1950s about people heating pennies on skillets and then dumping the hot pennies in the outstretched hands of trick-or-treaters,” Best said. “This morphed by the 1960s into poison and pins in candy bars.”

But there’s no evidence to back up these concerns. In a study published in 1993, Best of the University of Delaware looked for credible reports of poisoned Halloween candy, finding no credible cases up to that point. Since then, he has continued to scour for credible reports, including those about marijuana since legalization began to take root — but, again, has found no credible cases.

The closest thing to a case like the ones so many parents worry about comes from 1974. Back then, an 8-year-old died after eating Pixy Stix laced with cyanide. But the culprit wasn’t a stranger handing out candy to trick-or-treaters; it was the kid’s father, who apparently did it to get life insurance money.

So why do these concerns stick around? Best has a theory: “We live in a world of apocalyptic scenarios. Here we are; we have safer, healthier, longer lives than people in any other point in history. And we are constantly imagining that this could all fall apart in a nanosecond.” He added, “So I think that what happens is we translate a lot of our anxiety into fears about our children.”

The Halloween fears adapt to the events around us. After the 9/11 terrorist attacks, for example, Best uncovered unverified reports of kids getting cupcakes with jihadist messages.

With marijuana candy, the underlying concerns may be genuine fears about pot-laced edibles. As Best put it, “If you have marijuana-laced gummy bears out there, why not worry about that?”

Sabet, the anti-legalization activist, acknowledged as much: “With hundreds of kids poisoned by pot candy every year, it’s an ongoing concern no matter what day of the year it is. Halloween is the unofficial candy holiday, so people should take extra precautions even if the October 31sts of the past haven’t shown up anything yet.” (Poison centers report hundreds of childhood marijuana exposures each year, but they’re not all confirmed to be from candy or edibles, and none have reportedly happened as a result of trick-or-treating.)

Given that there has never been a confirmed deadly overdose to marijuana, though, these kinds of exposures are usually minor — involving some anxiety and perhaps some bizarre behavior, but nothing more severe.

As one example, New York Times columnist Maureen Dowd shared her own terrible experience of an edible overdose after Colorado began allowing sales in 2014, writing that she went through some truly horrifying anxiety: “I strained to remember where I was or even what I was wearing, touching my green corduroy jeans and staring at the exposed-brick wall. As my paranoia deepened, I became convinced that I had died and no one was telling me.”

(Confession: I had a similar experience with a marijuana chocolate — after I joked about Dowd and warned Vox readers about the risks of edibles.)

In another case, a father in Nebraska (where cannabis is still illegal) inadvertently ate some pot brownies, experienced some anxiety, and said some mean things to his cat.

But there have also been some very serious cases. In 2014, a 19-year-old reportedly ate six times the recommended amount of a marijuana cookie and jumped from a hotel balcony to his death.

Edibles are risky compared to other ways of consuming marijuana because the effects can take a while to kick in. When marijuana is smoked or vaporized, the effects are felt within minutes as the THC is absorbed into the lungs. Absorbing marijuana through the stomach, on the other hand, can take more than half an hour or even hours, especially if the pot is ingested after a full meal. That makes it harder to control the dose.

So if a newbie consumer notices the effects aren’t kicking in immediately, he or she might try eating more marijuana-laced goods to force the effect. But the ingestion can’t be sped up this way; it’s almost always going to take 30 minutes to a few hours. So when the high finally kicks in, it might build into an overwhelming feeling, even an overdose, due to all the edibles frivolously consumed to speed up the effect.

This is why states, including Colorado, have imposed extra rules on edibles following legalization. But the concerns of edible overdoses remain large.

When it comes to the Halloween concerns, though, Best argues that “if you’re looking for the dangers of marijuana legalization, this falls pretty far down the list.”