THE era of legal marijuana retail stores in Washington is set to begin in a few weeks, with an unprecedented and rigorous seed-to-sale regulatory system. Despite those regulations, the era also ushers in heightened anxieties about a potential increase in underage usage, even though sales are banned for customers under 21.

After spending 18 months working on regulations, Gov. Jay Inslee’s administration has finally launched a prevention campaign to address teen usage. At a news conference Tuesday, Inslee said the state was trying to give parents “tools that they need to keep our kids safe.”

The state Department of Health found $400,000 in its existing budget to pay for public-service announcements that encourage parents to talk to their kids about the harmful effects of marijuana on developing brains. Tens of thousands of copies of a prevention “tool kit” will be distributed through schools, thanks in part to funding from the marijuana industry.

This campaign should have started earlier, but better late than never. Initiative 502, which created the legal marijuana market, binds the state to fund a full-throated prevention campaign, paid for by proceeds from marijuana sin taxes. Because those taxes haven’t yet materialized, prevention efforts haven’t been funded — until now, on the eve of retail sales.

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The state Liquor Control Board, which is regulating the marijuana market, will rightly be banning edible marijuana products with packaging that appeals to teens. There should be no Joe Camel of the legal marijuana era.

Tuesday’s announcement should also be the start of a broader, deeper campaign to mitigate a potential increase in teen usage. A template is available: A decade of teen tobacco-prevention campaigns, paid for by the industry, dropped the rate of daily 12th-grade smokers from 29 percent in 1997 to 9 percent in 2013.

“Just Say No” messages won’t work in this era. A more nuanced approach, encouraging teens to forego marijuana until their brains fully form, is called for.

Paying for such a campaign will require discipline from the state Legislature. With other budget pressures, Olympia will be tempted to tap into future marijuana tax revenues that I-502 specifically dedicated to prevention.

Resist the urge. Voters approved I-502 in 2012 in part because it sought to shield teens from a legal marijuana market. Don’t mortgage their future health to pay for today’s fiscal demands.

Washington is leading the world in writing — from scratch — rigorous regulations for a recreational marijuana market. It should match that will and innovation in keeping teenagers as far away from that market as possible.

Editorial board members are editorial page editor Kate Riley, Frank A. Blethen, Ryan Blethen, Sharon Pian Chan, Lance Dickie, Jonathan Martin, Erik Smith, Thanh Tan, William K. Blethen (emeritus) and Robert C. Blethen (emeritus).