Concern grows over accidental ingestion of THC-laced food

SAN JOSE, Calif. (KGO) -- California voters will vote in November whether to legalize marijuana. If restrictions are lifted, will there be more cases like the one in San Francisco in which 19 young people got sick after ingesting marijuana-laced candy?

RELATED: SFPD investigating source of THC-laced candy that sickened 19

Medicinal marijuana dispensaries have to follow tough regulations to make sure their products don't end up in the wrong hands, yet THC-laced cookies, brownies and now candy have shown up on school campuses and parties.

Experts say it is difficult to detect adulteration.

The potential for getting sick from ingesting food infused with components of marijuana isn't restricted to just young people or innocent victims.

It happens to adults who buy such products at medical dispensaries. They don't feel the effect for up to three hours, so they eat even more.

"It's very, very easy to do, especially when there are items that may have a good flavor to them. It might be a piece of chocolate. It might be a brownie or something like that. You might want to eat too much of it," Elemental Wellness Center's Lauren Winters said.

In Colorado, where marijuana has been legalized, Denver police produced a video to warn parents before Halloween that candy infused with THC from marijuana is impossible to detect.

"The problem is that some of these products look so similar to candy that's been on the market that we've eaten as children that there's really no way for a child or a parent or anybody, even an expert in the field, to tell you whether or not a product is infused or not," Urban Dispensary's Patrick Johnson said.

Elemental Wellness Center in San Jose showed ABC7 News examples of the tamper-proof packaging it uses to dispense medicinal marijuana.

Manufacturers of the THC-infused edibles use child-proof caps and seals.

However, with Proposition 64 on the November ballot, opponents to legalizing marijuana warn that cases like the 19 who got sick in San Francisco from laced candy are not surprising.

"We're not surprised. We've seen a very dramatic increase in children being exposed all over the country where marijuana is prevalent, particularly in Colorado and Washington," Citizens Against Legalizing Marijuana spokesperson Scott Chipman said.

County and state officials said they do not keep records on cases of children who get sick from THC-infused food.