If Time magazine isn't impressed by your would-be moral panic, you're doing it wrong. In LA County, a sheriff sent out a general call of alarm -- see, since marijuana-laced candy and treats exist, somebody might try to feed them to your children when they go trick or treating. 

But Time.com soothes:

Like earlier warnings about razors in apples and other poisoned candy, there's no evidence that any such misdeed has ever occurred. Think about it for a moment: why would a presumed drug user or dealer waste expensive and often difficult to acquire drugs on children?

That's a really good question: 

Marijuana brownies are being sold for $9 apiece, or $75 for 10, at a San Francisco dispensary, for example. A Colorado group reported selling them recently for $8 apiece. Compare that with the average cost of ordinary candy — several cents per piece. With folks typically giving out not more than $1 worth of loot per trick-or-treater, adding pot-laden snacks to the mix would rapidly make for one expensive trick in the Great Recession!

The L.A. Sheriff had also warned about this possibility last year, with no reports of any actual child victims.

Weirdly rational of you, Time. And bonus points for linking to numerous Snopes.com articles which defuse many of the classic Halloween horror stories.

Sure, it's possible that asshole would try to make a kid sick by giving them a weed lolly. But that's probably not going to happen. 

Katherine Mangu-Ward on how your child's costume might kill them (according to the Consumer Product Safety Commission). 

Reason on the childrens and Halloween.

Update: Jesse Walker just pointed out the why of this strangely sensible Time.com article -- it was written by Reason contributor Maia Szalavitz.