Actor and cannabis activist Tommy Chong stepped on stage moments after the clock struck 4:20 p.m. at Civic Center Park, where thousands gathered to celebrate the annual Mile High 420 Festival.

Chong’s message? Share your stash and meet someone new.

“It’s great to be here in Denver on this day to celebrate,” said the actor who most famously starred in the 1978 comedy “Cheech and Chong; Up in Smoke,” including other films featuring Cheech Marin.

Chong appeared on stage at a time when questions are being leveled at the marijuana industry over the health consequences of consuming the drug and its safety record as a product in Colorado.

A New York Times investigation, reprinted by The Denver Gazette last year, explored how doctors are contending with the effects of an “explosion in the use of the drug and its intensity,” and concluded that “with more people consuming more potent cannabis more often, a growing number, mostly chronic users, are enduring serious health consequences.”

The New York Times said the “accumulating harm is broader and more severe than previously reported. And gaps in state regulations, limited public health messaging and federal restraints on research have left many consumers, government officials and even medical practitioners in the dark about such outcomes.”

More recently, a Denver Gazette investigation, citing industry insiders and researchers, found that the Colorado industry is riddled with loopholes that allow consumers to be deceived about everything from the marijuana’s potency, to the prevalence of dangerous pesticides, solvents and mold.”

The investigation found that contaminated marijuana ends up in shops in Colorado, with state officials issuing health and safety recalls more than 40 times in the past three years. But when problems are found, and a recall is needed, the average time from the first sale to when a recall is issued is nine months.

A spokesperson for the state’s Marijuana Enforcement Division said Colorado has “strong systems in place to audit and monitor licensed testing facilities’ processes and reporting of results, including annual audits at testing facilities by the Colorado Department of Public Health and Environment.”

Some trace the 420 festival back to Marin County, Calif., in 1971, when five students at San Rafael High School would meet at 4:20 p.m. by a campus statue to smoke marijuana.

This year’s festival in Denver featured known and up and coming artists, including Cordae, Bones Thugs-N-Harmony, Conway the Machine, Kaliii, Na-Kel Smith and Souls of Mischief.

Colorado state laws prohibit smoking cannabis in public spaces. Authorities don’t typically enforce smoking laws at the 420 festival grounds.

This was the first year in Mile High 420 Festival history charged an entry fee.