A Massachusetts ballot measure in November would allow adults to possess up to 10 ounces of marijuana inside their residences and grow up to six plants. GETTY IMAGES

In a scathing op-ed published in the Boston Globe, three political heavyweights in Massachusetts urged the state’s voters Monday not to support marijuana legalization when it appears on the November ballot. Gov. Charlie Baker, Boston Mayor Marty Walsh and Attorney General Maura Healey argued legalization would increase cannabis use among minors and impair their development.

“The question before us now is whether marijuana should be fully legal and widely available for commercial sale,” they wrote. “We think the answer is ‘no.’ ”

The politicians cited a Rocky Mountain High Intensity Drug Trafficking Area report that said while use among minors has declined nationwide in recent years, it has increased in states such as Colorado, where cannabis has been legalized entirely.

Massachusetts decriminalized the drug in 2008 and legalized it in 2012 for medicinal purposes, but has not allowed residents to use it recreationally. A measure has been placed on the November ballot that would allow adults to possess up to 10 ounces of marijuana inside their residences and grow up to six plants.

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In the op-ed, the politicians argued that cannabis legalization also presents risks for adults and could result in costly increases in medical expenses. “Here in Massachusetts, we face the possibility that any new revenue would be vastly insufficient to cover the cost of ambulance rides, emergency room visits, and treatment,” they wrote. “And these are just the hard costs; they don’t include the suffering of the injured and their families.”

The ballot measure is separate from another measure that has pushed for lawmakers to legalize marijuana. Dick Evans, chairman of the Campaign to Regulate Marijuana Like Alcohol, said he hopes to see the drug legalized through either avenue.

“It’s time for Massachusetts to replace the failed policy of marijuana prohibition with a more sensible system in which marijuana is regulated similarly to alcohol,” Evans told the Weed Blog. “Whether it happens in the legislature or at the ballot box, the result will be the same.”

Four states and Washington, D.C., have legalized the drug entirely; 23 states allow residents to use the drug for medicinal purposes.