BOSTON -- Marijuana legalization will increase arrests and addiction, argued two Western Massachusetts county sheriffs on Monday as they sought to raise taxes on the marijuana industry to fund drug addiction treatment.

Hampden County Sheriff Nick Cocchi and Hampshire County Sheriff Patrick Cahillane testified at the final public hearing of the Legislature's Joint Committee on Marijuana Policy.

"There has to be a treatment component for all of our safety," Cahillane said. "It's not about kids smoking the occasional joint. The continued use of marijuana can lead to the types of addiction found in smoking and drinking."

County sheriffs have been at the forefront of a push to raise the maximum tax rate on legal recreational marijuana to 17 percent, from the 12 percent that was passed by a ballot initiative in November. The additional 5 percent tax would go toward addiction treatment.

A bill to raise the tax rate to support public and private addiction treatment programs, H.3504, was sponsored by Reps. Brian Ashe, D-Longmeadow, and John Velis, D-Westfield, and co-sponsored by nine of Massachusetts' 14 county sheriffs.

Cahillane said he anticipates an increase in arrests for driving under the influence of marijuana and other criminal activity. "Not everyone will smoke responsibly, much the same way many people do not drink responsibly," Cahillane said.

Cahillane said the correctional system is already overwhelmed by the need for substance abuse treatment, and he anticipated that the problem will only get worse with more widespread marijuana use.

Cocchi said not everyone who smokes marijuana will become an addict, but someone who already has addictive tendencies and starts smoking marijuana could become addicted to harder drugs.

Cocchi said there is already a shortage of treatment beds for people struggling with substance abuse, and he gets calls regularly from family members of addicts desperate for treatment. "We are searching and starving for resources and beds," Cocchi said.

With marijuana legalization, Cocchi said, "There's a revenue source that's never been tapped into before" available to fund addiction treatment.

Sen. Patricia Jehlen, D-Somerville, who co-chairs the legislative marijuana committee, has suggested keeping marijuana taxes low in order to curb the black market for marijuana. But other lawmakers have urged the committee to raise the rate. Marijuana tax rates elsewhere range from 10 percent in Maine to 37 percent in Washington State.

The Yes on 4 coalition, which sponsored the ballot question legalizing marijuana, has said the tax rate should be high enough to cover the costs of overseeing the industry but low enough to reduce the illegal market.

House Speaker Robert DeLeo, D-Winthrop, has voiced support for the idea of using marijuana revenue to create a new fund to address substance abuse recovery.