Because of powdered milk's resemblance to cocaine and other drugs, powdered milk is sometimes used in film-making as a non-toxic prop that may be inhaled.
Other methods listed on nypost.com are -
“It’s usually cornstarch, but you have to put a bit of baby powder
into it, because starch is too sticky and heavy,” says Gillian
Albinski, the property master on Homeland.
“I always use powdered lactose,” says longtime prop master Mychael
Bates, who worked on 2011’s Horrible Bosses.
Colin Farrell didn’t seem to mind. He was even snorting the powder
off-camera in order to stay in character, Bates says.
For the lactose-intolerant, something like a vitamin B powder (inositol),
available at health-food stores, might be substituted.
Snorting any powder over multiple takes can cause an actor to become
congested. (Or just angry.) In that case, the prop masters will
sometimes coat the inside of the coke straw with Vaseline. When the
powder is snorted, most of it sticks to the straw instead of going up
the actor’s nose.
Besides heroin, “Homeland” includes scenes of Morgan Saylor’s character Dana Brody smoking pot.
“I’ve worked on shows where actors have wanted to smoke the real thing, and I was constantly fighting to take away their real bags,” Albinski says. “Oregano smells so much like the real thing, you have to check carefully to make sure they haven’t switched it out.”
Other prop masters do use the real thing — sort of. Companies, including legalbuds.com, sell ganja without the active ingredient THC. It looks and burns like marijuana, but it won’t get anyone high.
Crack rocks are created by dropping globs of Krazy Glue into a pile of baking soda.